Google Git
Sign in
llvm / llvm-project / 15d1ee36720ff24323f55452ae3cfb63f318c3f3 / . / llvm / lib / Transforms / IPO / AttributorAttributes.cpp
blob: d6127a8df6282ccb155154176ba98335919929b4 [file] [log] [blame]
//===- AttributorAttributes.cpp - Attributes for Attributor deduction -----===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// See the Attributor.h file comment and the class descriptions in that file for
// more information.
//
//===----------------------------------------------------------------------===//
#include "llvm/Transforms/IPO/Attributor.h"
#include "llvm/ADT/SCCIterator.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Analysis/AssumeBundleQueries.h"
#include "llvm/Analysis/AssumptionCache.h"
#include "llvm/Analysis/CaptureTracking.h"
#include "llvm/Analysis/LazyValueInfo.h"
#include "llvm/Analysis/MemoryBuiltins.h"
#include "llvm/Analysis/ScalarEvolution.h"
#include "llvm/Analysis/TargetTransformInfo.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/Instruction.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/NoFolder.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Transforms/IPO/ArgumentPromotion.h"
#include "llvm/Transforms/Utils/Local.h"
#include <cassert>
using namespace llvm;
#define DEBUG_TYPE "attributor"
static cl::opt<bool> ManifestInternal(
"attributor-manifest-internal", cl::Hidden,
cl::desc("Manifest Attributor internal string attributes."),
cl::init(false));
static cl::opt<int> MaxHeapToStackSize("max-heap-to-stack-size", cl::init(128),
cl::Hidden);
template <>
unsigned llvm::PotentialConstantIntValuesState::MaxPotentialValues = 0;
static cl::opt<unsigned, true> MaxPotentialValues(
"attributor-max-potential-values", cl::Hidden,
cl::desc("Maximum number of potential values to be "
"tracked for each position."),
cl::location(llvm::PotentialConstantIntValuesState::MaxPotentialValues),
cl::init(7));
STATISTIC(NumAAs, "Number of abstract attributes created");
// Some helper macros to deal with statistics tracking.
//
// Usage:
// For simple IR attribute tracking overload trackStatistics in the abstract
// attribute and choose the right STATS_DECLTRACK_********* macro,
// e.g.,:
// void trackStatistics() const override {
// STATS_DECLTRACK_ARG_ATTR(returned)
// }
// If there is a single "increment" side one can use the macro
// STATS_DECLTRACK with a custom message. If there are multiple increment
// sides, STATS_DECL and STATS_TRACK can also be used separately.
//
#define BUILD_STAT_MSG_IR_ATTR(TYPE, NAME) \
("Number of " #TYPE " marked '" #NAME "'")
#define BUILD_STAT_NAME(NAME, TYPE) NumIR##TYPE##_##NAME
#define STATS_DECL_(NAME, MSG) STATISTIC(NAME, MSG);
#define STATS_DECL(NAME, TYPE, MSG) \
STATS_DECL_(BUILD_STAT_NAME(NAME, TYPE), MSG);
#define STATS_TRACK(NAME, TYPE) ++(BUILD_STAT_NAME(NAME, TYPE));
#define STATS_DECLTRACK(NAME, TYPE, MSG) \
{ \
STATS_DECL(NAME, TYPE, MSG) \
STATS_TRACK(NAME, TYPE) \
}
#define STATS_DECLTRACK_ARG_ATTR(NAME) \
STATS_DECLTRACK(NAME, Arguments, BUILD_STAT_MSG_IR_ATTR(arguments, NAME))
#define STATS_DECLTRACK_CSARG_ATTR(NAME) \
STATS_DECLTRACK(NAME, CSArguments, \
BUILD_STAT_MSG_IR_ATTR(call site arguments, NAME))
#define STATS_DECLTRACK_FN_ATTR(NAME) \
STATS_DECLTRACK(NAME, Function, BUILD_STAT_MSG_IR_ATTR(functions, NAME))
#define STATS_DECLTRACK_CS_ATTR(NAME) \
STATS_DECLTRACK(NAME, CS, BUILD_STAT_MSG_IR_ATTR(call site, NAME))
#define STATS_DECLTRACK_FNRET_ATTR(NAME) \
STATS_DECLTRACK(NAME, FunctionReturn, \
BUILD_STAT_MSG_IR_ATTR(function returns, NAME))
#define STATS_DECLTRACK_CSRET_ATTR(NAME) \
STATS_DECLTRACK(NAME, CSReturn, \
BUILD_STAT_MSG_IR_ATTR(call site returns, NAME))
#define STATS_DECLTRACK_FLOATING_ATTR(NAME) \
STATS_DECLTRACK(NAME, Floating, \
("Number of floating values known to be '" #NAME "'"))
// Specialization of the operator<< for abstract attributes subclasses. This
// disambiguates situations where multiple operators are applicable.
namespace llvm {
#define PIPE_OPERATOR(CLASS) \
raw_ostream &operator<<(raw_ostream &OS, const CLASS &AA) { \
return OS << static_cast<const AbstractAttribute &>(AA); \
}
PIPE_OPERATOR(AAIsDead)
PIPE_OPERATOR(AANoUnwind)
PIPE_OPERATOR(AANoSync)
PIPE_OPERATOR(AANoRecurse)
PIPE_OPERATOR(AAWillReturn)
PIPE_OPERATOR(AANoReturn)
PIPE_OPERATOR(AAReturnedValues)
PIPE_OPERATOR(AANonNull)
PIPE_OPERATOR(AANoAlias)
PIPE_OPERATOR(AADereferenceable)
PIPE_OPERATOR(AAAlign)
PIPE_OPERATOR(AANoCapture)
PIPE_OPERATOR(AAValueSimplify)
PIPE_OPERATOR(AANoFree)
PIPE_OPERATOR(AAHeapToStack)
PIPE_OPERATOR(AAReachability)
PIPE_OPERATOR(AAMemoryBehavior)
PIPE_OPERATOR(AAMemoryLocation)
PIPE_OPERATOR(AAValueConstantRange)
PIPE_OPERATOR(AAPrivatizablePtr)
PIPE_OPERATOR(AAUndefinedBehavior)
PIPE_OPERATOR(AAPotentialValues)
PIPE_OPERATOR(AANoUndef)
#undef PIPE_OPERATOR
} // namespace llvm
namespace {
static Optional<ConstantInt *>
getAssumedConstantInt(Attributor &A, const Value &V,
const AbstractAttribute &AA,
bool &UsedAssumedInformation) {
Optional<Constant *> C = A.getAssumedConstant(V, AA, UsedAssumedInformation);
if (C.hasValue())
return dyn_cast_or_null<ConstantInt>(C.getValue());
return llvm::None;
}
/// Get pointer operand of memory accessing instruction. If \p I is
/// not a memory accessing instruction, return nullptr. If \p AllowVolatile,
/// is set to false and the instruction is volatile, return nullptr.
static const Value *getPointerOperand(const Instruction *I,
bool AllowVolatile) {
if (auto *LI = dyn_cast<LoadInst>(I)) {
if (!AllowVolatile && LI->isVolatile())
return nullptr;
return LI->getPointerOperand();
}
if (auto *SI = dyn_cast<StoreInst>(I)) {
if (!AllowVolatile && SI->isVolatile())
return nullptr;
return SI->getPointerOperand();
}
if (auto *CXI = dyn_cast<AtomicCmpXchgInst>(I)) {
if (!AllowVolatile && CXI->isVolatile())
return nullptr;
return CXI->getPointerOperand();
}
if (auto *RMWI = dyn_cast<AtomicRMWInst>(I)) {
if (!AllowVolatile && RMWI->isVolatile())
return nullptr;
return RMWI->getPointerOperand();
}
return nullptr;
}
/// Helper function to create a pointer of type \p ResTy, based on \p Ptr, and
/// advanced by \p Offset bytes. To aid later analysis the method tries to build
/// getelement pointer instructions that traverse the natural type of \p Ptr if
/// possible. If that fails, the remaining offset is adjusted byte-wise, hence
/// through a cast to i8*.
///
/// TODO: This could probably live somewhere more prominantly if it doesn't
/// already exist.
static Value *constructPointer(Type *ResTy, Value *Ptr, int64_t Offset,
IRBuilder<NoFolder> &IRB, const DataLayout &DL) {
assert(Offset >= 0 && "Negative offset not supported yet!");
LLVM_DEBUG(dbgs() << "Construct pointer: " << *Ptr << " + " << Offset
<< "-bytes as " << *ResTy << "\n");
// The initial type we are trying to traverse to get nice GEPs.
Type *Ty = Ptr->getType();
SmallVector<Value *, 4> Indices;
std::string GEPName = Ptr->getName().str();
while (Offset) {
uint64_t Idx, Rem;
if (auto *STy = dyn_cast<StructType>(Ty)) {
const StructLayout *SL = DL.getStructLayout(STy);
if (int64_t(SL->getSizeInBytes()) < Offset)
break;
Idx = SL->getElementContainingOffset(Offset);
assert(Idx < STy->getNumElements() && "Offset calculation error!");
Rem = Offset - SL->getElementOffset(Idx);
Ty = STy->getElementType(Idx);
} else if (auto *PTy = dyn_cast<PointerType>(Ty)) {
Ty = PTy->getElementType();
if (!Ty->isSized())
break;
uint64_t ElementSize = DL.getTypeAllocSize(Ty);
assert(ElementSize && "Expected type with size!");
Idx = Offset / ElementSize;
Rem = Offset % ElementSize;
} else {
// Non-aggregate type, we cast and make byte-wise progress now.
break;
}
LLVM_DEBUG(errs() << "Ty: " << *Ty << " Offset: " << Offset
<< " Idx: " << Idx << " Rem: " << Rem << "\n");
GEPName += "." + std::to_string(Idx);
Indices.push_back(ConstantInt::get(IRB.getInt32Ty(), Idx));
Offset = Rem;
}
// Create a GEP if we collected indices above.
if (Indices.size())
Ptr = IRB.CreateGEP(Ptr, Indices, GEPName);
// If an offset is left we use byte-wise adjustment.
if (Offset) {
Ptr = IRB.CreateBitCast(Ptr, IRB.getInt8PtrTy());
Ptr = IRB.CreateGEP(Ptr, IRB.getInt32(Offset),
GEPName + ".b" + Twine(Offset));
}
// Ensure the result has the requested type.
Ptr = IRB.CreateBitOrPointerCast(Ptr, ResTy, Ptr->getName() + ".cast");
LLVM_DEBUG(dbgs() << "Constructed pointer: " << *Ptr << "\n");
return Ptr;
}
/// Recursively visit all values that might become \p IRP at some point. This
/// will be done by looking through cast instructions, selects, phis, and calls
/// with the "returned" attribute. Once we cannot look through the value any
/// further, the callback \p VisitValueCB is invoked and passed the current
/// value, the \p State, and a flag to indicate if we stripped anything.
/// Stripped means that we unpacked the value associated with \p IRP at least
/// once. Note that the value used for the callback may still be the value
/// associated with \p IRP (due to PHIs). To limit how much effort is invested,
/// we will never visit more values than specified by \p MaxValues.
template <typename AAType, typename StateTy>
static bool genericValueTraversal(
Attributor &A, IRPosition IRP, const AAType &QueryingAA, StateTy &State,
function_ref<bool(Value &, const Instruction *, StateTy &, bool)>
VisitValueCB,
const Instruction *CtxI, bool UseValueSimplify = true, int MaxValues = 16,
function_ref<Value *(Value *)> StripCB = nullptr) {
const AAIsDead *LivenessAA = nullptr;
if (IRP.getAnchorScope())
LivenessAA = &A.getAAFor<AAIsDead>(
QueryingAA, IRPosition::function(*IRP.getAnchorScope()),
/* TrackDependence */ false);
bool AnyDead = false;
using Item = std::pair<Value *, const Instruction *>;
SmallSet<Item, 16> Visited;
SmallVector<Item, 16> Worklist;
Worklist.push_back({&IRP.getAssociatedValue(), CtxI});
int Iteration = 0;
do {
Item I = Worklist.pop_back_val();
Value *V = I.first;
CtxI = I.second;
if (StripCB)
V = StripCB(V);
// Check if we should process the current value. To prevent endless
// recursion keep a record of the values we followed!
if (!Visited.insert(I).second)
continue;
// Make sure we limit the compile time for complex expressions.
if (Iteration++ >= MaxValues)
return false;
// Explicitly look through calls with a "returned" attribute if we do
// not have a pointer as stripPointerCasts only works on them.
Value *NewV = nullptr;
if (V->getType()->isPointerTy()) {
NewV = V->stripPointerCasts();
} else {
auto *CB = dyn_cast<CallBase>(V);
if (CB && CB->getCalledFunction()) {
for (Argument &Arg : CB->getCalledFunction()->args())
if (Arg.hasReturnedAttr()) {
NewV = CB->getArgOperand(Arg.getArgNo());
break;
}
}
}
if (NewV && NewV != V) {
Worklist.push_back({NewV, CtxI});
continue;
}
// Look through select instructions, visit both potential values.
if (auto *SI = dyn_cast<SelectInst>(V)) {
Worklist.push_back({SI->getTrueValue(), CtxI});
Worklist.push_back({SI->getFalseValue(), CtxI});
continue;
}
// Look through phi nodes, visit all live operands.
if (auto *PHI = dyn_cast<PHINode>(V)) {
assert(LivenessAA &&
"Expected liveness in the presence of instructions!");
for (unsigned u = 0, e = PHI->getNumIncomingValues(); u < e; u++) {
BasicBlock *IncomingBB = PHI->getIncomingBlock(u);
if (A.isAssumedDead(*IncomingBB->getTerminator(), &QueryingAA,
LivenessAA,
/* CheckBBLivenessOnly */ true)) {
AnyDead = true;
continue;
}
Worklist.push_back(
{PHI->getIncomingValue(u), IncomingBB->getTerminator()});
}
continue;
}
if (UseValueSimplify && !isa<Constant>(V)) {
bool UsedAssumedInformation = false;
Optional<Constant *> C =
A.getAssumedConstant(*V, QueryingAA, UsedAssumedInformation);
if (!C.hasValue())
continue;
if (Value *NewV = C.getValue()) {
Worklist.push_back({NewV, CtxI});
continue;
}
}
// Once a leaf is reached we inform the user through the callback.
if (!VisitValueCB(*V, CtxI, State, Iteration > 1))
return false;
} while (!Worklist.empty());
// If we actually used liveness information so we have to record a dependence.
if (AnyDead)
A.recordDependence(*LivenessAA, QueryingAA, DepClassTy::OPTIONAL);
// All values have been visited.
return true;
}
const Value *stripAndAccumulateMinimalOffsets(
Attributor &A, const AbstractAttribute &QueryingAA, const Value *Val,
const DataLayout &DL, APInt &Offset, bool AllowNonInbounds,
bool UseAssumed = false) {
auto AttributorAnalysis = [&](Value &V, APInt &ROffset) -> bool {
const IRPosition &Pos = IRPosition::value(V);
// Only track dependence if we are going to use the assumed info.
const AAValueConstantRange &ValueConstantRangeAA =
A.getAAFor<AAValueConstantRange>(QueryingAA, Pos,
/* TrackDependence */ UseAssumed);
ConstantRange Range = UseAssumed ? ValueConstantRangeAA.getAssumed()
: ValueConstantRangeAA.getKnown();
// We can only use the lower part of the range because the upper part can
// be higher than what the value can really be.
ROffset = Range.getSignedMin();
return true;
};
return Val->stripAndAccumulateConstantOffsets(DL, Offset, AllowNonInbounds,
AttributorAnalysis);
}
static const Value *getMinimalBaseOfAccsesPointerOperand(
Attributor &A, const AbstractAttribute &QueryingAA, const Instruction *I,
int64_t &BytesOffset, const DataLayout &DL, bool AllowNonInbounds = false) {
const Value *Ptr = getPointerOperand(I, /* AllowVolatile */ false);
if (!Ptr)
return nullptr;
APInt OffsetAPInt(DL.getIndexTypeSizeInBits(Ptr->getType()), 0);
const Value *Base = stripAndAccumulateMinimalOffsets(
A, QueryingAA, Ptr, DL, OffsetAPInt, AllowNonInbounds);
BytesOffset = OffsetAPInt.getSExtValue();
return Base;
}
static const Value *
getBasePointerOfAccessPointerOperand(const Instruction *I, int64_t &BytesOffset,
const DataLayout &DL,
bool AllowNonInbounds = false) {
const Value *Ptr = getPointerOperand(I, /* AllowVolatile */ false);
if (!Ptr)
return nullptr;
return GetPointerBaseWithConstantOffset(Ptr, BytesOffset, DL,
AllowNonInbounds);
}
/// Helper function to clamp a state \p S of type \p StateType with the
/// information in \p R and indicate/return if \p S did change (as-in update is
/// required to be run again).
template <typename StateType>
ChangeStatus clampStateAndIndicateChange(StateType &S, const StateType &R) {
auto Assumed = S.getAssumed();
S ^= R;
return Assumed == S.getAssumed() ? ChangeStatus::UNCHANGED
: ChangeStatus::CHANGED;
}
/// Clamp the information known for all returned values of a function
/// (identified by \p QueryingAA) into \p S.
template <typename AAType, typename StateType = typename AAType::StateType>
static void clampReturnedValueStates(Attributor &A, const AAType &QueryingAA,
StateType &S) {
LLVM_DEBUG(dbgs() << "[Attributor] Clamp return value states for "
<< QueryingAA << " into " << S << "\n");
assert((QueryingAA.getIRPosition().getPositionKind() ==
IRPosition::IRP_RETURNED ||
QueryingAA.getIRPosition().getPositionKind() ==
IRPosition::IRP_CALL_SITE_RETURNED) &&
"Can only clamp returned value states for a function returned or call "
"site returned position!");
// Use an optional state as there might not be any return values and we want
// to join (IntegerState::operator&) the state of all there are.
Optional<StateType> T;
// Callback for each possibly returned value.
auto CheckReturnValue = [&](Value &RV) -> bool {
const IRPosition &RVPos = IRPosition::value(RV);
const AAType &AA = A.getAAFor<AAType>(QueryingAA, RVPos);
LLVM_DEBUG(dbgs() << "[Attributor] RV: " << RV << " AA: " << AA.getAsStr()
<< " @ " << RVPos << "\n");
const StateType &AAS = AA.getState();
if (T.hasValue())
*T &= AAS;
else
T = AAS;
LLVM_DEBUG(dbgs() << "[Attributor] AA State: " << AAS << " RV State: " << T
<< "\n");
return T->isValidState();
};
if (!A.checkForAllReturnedValues(CheckReturnValue, QueryingAA))
S.indicatePessimisticFixpoint();
else if (T.hasValue())
S ^= *T;
}
/// Helper class for generic deduction: return value -> returned position.
template <typename AAType, typename BaseType,
typename StateType = typename BaseType::StateType>
struct AAReturnedFromReturnedValues : public BaseType {
AAReturnedFromReturnedValues(const IRPosition &IRP, Attributor &A)
: BaseType(IRP, A) {}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
StateType S(StateType::getBestState(this->getState()));
clampReturnedValueStates<AAType, StateType>(A, *this, S);
// TODO: If we know we visited all returned values, thus no are assumed
// dead, we can take the known information from the state T.
return clampStateAndIndicateChange<StateType>(this->getState(), S);
}
};
/// Clamp the information known at all call sites for a given argument
/// (identified by \p QueryingAA) into \p S.
template <typename AAType, typename StateType = typename AAType::StateType>
static void clampCallSiteArgumentStates(Attributor &A, const AAType &QueryingAA,
StateType &S) {
LLVM_DEBUG(dbgs() << "[Attributor] Clamp call site argument states for "
<< QueryingAA << " into " << S << "\n");
assert(QueryingAA.getIRPosition().getPositionKind() ==
IRPosition::IRP_ARGUMENT &&
"Can only clamp call site argument states for an argument position!");
// Use an optional state as there might not be any return values and we want
// to join (IntegerState::operator&) the state of all there are.
Optional<StateType> T;
// The argument number which is also the call site argument number.
unsigned ArgNo = QueryingAA.getIRPosition().getCallSiteArgNo();
auto CallSiteCheck = [&](AbstractCallSite ACS) {
const IRPosition &ACSArgPos = IRPosition::callsite_argument(ACS, ArgNo);
// Check if a coresponding argument was found or if it is on not associated
// (which can happen for callback calls).
if (ACSArgPos.getPositionKind() == IRPosition::IRP_INVALID)
return false;
const AAType &AA = A.getAAFor<AAType>(QueryingAA, ACSArgPos);
LLVM_DEBUG(dbgs() << "[Attributor] ACS: " << *ACS.getInstruction()
<< " AA: " << AA.getAsStr() << " @" << ACSArgPos << "\n");
const StateType &AAS = AA.getState();
if (T.hasValue())
*T &= AAS;
else
T = AAS;
LLVM_DEBUG(dbgs() << "[Attributor] AA State: " << AAS << " CSA State: " << T
<< "\n");
return T->isValidState();
};
bool AllCallSitesKnown;
if (!A.checkForAllCallSites(CallSiteCheck, QueryingAA, true,
AllCallSitesKnown))
S.indicatePessimisticFixpoint();
else if (T.hasValue())
S ^= *T;
}
/// Helper class for generic deduction: call site argument -> argument position.
template <typename AAType, typename BaseType,
typename StateType = typename AAType::StateType>
struct AAArgumentFromCallSiteArguments : public BaseType {
AAArgumentFromCallSiteArguments(const IRPosition &IRP, Attributor &A)
: BaseType(IRP, A) {}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
StateType S(StateType::getBestState(this->getState()));
clampCallSiteArgumentStates<AAType, StateType>(A, *this, S);
// TODO: If we know we visited all incoming values, thus no are assumed
// dead, we can take the known information from the state T.
return clampStateAndIndicateChange<StateType>(this->getState(), S);
}
};
/// Helper class for generic replication: function returned -> cs returned.
template <typename AAType, typename BaseType,
typename StateType = typename BaseType::StateType>
struct AACallSiteReturnedFromReturned : public BaseType {
AACallSiteReturnedFromReturned(const IRPosition &IRP, Attributor &A)
: BaseType(IRP, A) {}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
assert(this->getIRPosition().getPositionKind() ==
IRPosition::IRP_CALL_SITE_RETURNED &&
"Can only wrap function returned positions for call site returned "
"positions!");
auto &S = this->getState();
const Function *AssociatedFunction =
this->getIRPosition().getAssociatedFunction();
if (!AssociatedFunction)
return S.indicatePessimisticFixpoint();
IRPosition FnPos = IRPosition::returned(*AssociatedFunction);
const AAType &AA = A.getAAFor<AAType>(*this, FnPos);
return clampStateAndIndicateChange(S, AA.getState());
}
};
/// Helper function to accumulate uses.
template <class AAType, typename StateType = typename AAType::StateType>
static void followUsesInContext(AAType &AA, Attributor &A,
MustBeExecutedContextExplorer &Explorer,
const Instruction *CtxI,
SetVector<const Use *> &Uses,
StateType &State) {
auto EIt = Explorer.begin(CtxI), EEnd = Explorer.end(CtxI);
for (unsigned u = 0; u < Uses.size(); ++u) {
const Use *U = Uses[u];
if (const Instruction *UserI = dyn_cast<Instruction>(U->getUser())) {
bool Found = Explorer.findInContextOf(UserI, EIt, EEnd);
if (Found && AA.followUseInMBEC(A, U, UserI, State))
for (const Use &Us : UserI->uses())
Uses.insert(&Us);
}
}
}
/// Use the must-be-executed-context around \p I to add information into \p S.
/// The AAType class is required to have `followUseInMBEC` method with the
/// following signature and behaviour:
///
/// bool followUseInMBEC(Attributor &A, const Use *U, const Instruction *I)
/// U - Underlying use.
/// I - The user of the \p U.
/// Returns true if the value should be tracked transitively.
///
template <class AAType, typename StateType = typename AAType::StateType>
static void followUsesInMBEC(AAType &AA, Attributor &A, StateType &S,
Instruction &CtxI) {
// Container for (transitive) uses of the associated value.
SetVector<const Use *> Uses;
for (const Use &U : AA.getIRPosition().getAssociatedValue().uses())
Uses.insert(&U);
MustBeExecutedContextExplorer &Explorer =
A.getInfoCache().getMustBeExecutedContextExplorer();
followUsesInContext<AAType>(AA, A, Explorer, &CtxI, Uses, S);
if (S.isAtFixpoint())
return;
SmallVector<const BranchInst *, 4> BrInsts;
auto Pred = [&](const Instruction *I) {
if (const BranchInst *Br = dyn_cast<BranchInst>(I))
if (Br->isConditional())
BrInsts.push_back(Br);
return true;
};
// Here, accumulate conditional branch instructions in the context. We
// explore the child paths and collect the known states. The disjunction of
// those states can be merged to its own state. Let ParentState_i be a state
// to indicate the known information for an i-th branch instruction in the
// context. ChildStates are created for its successors respectively.
//
// ParentS_1 = ChildS_{1, 1} /\ ChildS_{1, 2} /\ ... /\ ChildS_{1, n_1}
// ParentS_2 = ChildS_{2, 1} /\ ChildS_{2, 2} /\ ... /\ ChildS_{2, n_2}
// ...
// ParentS_m = ChildS_{m, 1} /\ ChildS_{m, 2} /\ ... /\ ChildS_{m, n_m}
//
// Known State |= ParentS_1 \/ ParentS_2 \/... \/ ParentS_m
//
// FIXME: Currently, recursive branches are not handled. For example, we
// can't deduce that ptr must be dereferenced in below function.
//
// void f(int a, int c, int *ptr) {
// if(a)
// if (b) {
// *ptr = 0;
// } else {
// *ptr = 1;
// }
// else {
// if (b) {
// *ptr = 0;
// } else {
// *ptr = 1;
// }
// }
// }
Explorer.checkForAllContext(&CtxI, Pred);
for (const BranchInst *Br : BrInsts) {
StateType ParentState;
// The known state of the parent state is a conjunction of children's
// known states so it is initialized with a best state.
ParentState.indicateOptimisticFixpoint();
for (const BasicBlock *BB : Br->successors()) {
StateType ChildState;
size_t BeforeSize = Uses.size();
followUsesInContext(AA, A, Explorer, &BB->front(), Uses, ChildState);
// Erase uses which only appear in the child.
for (auto It = Uses.begin() + BeforeSize; It != Uses.end();)
It = Uses.erase(It);
ParentState &= ChildState;
}
// Use only known state.
S += ParentState;
}
}
/// -----------------------NoUnwind Function Attribute--------------------------
struct AANoUnwindImpl : AANoUnwind {
AANoUnwindImpl(const IRPosition &IRP, Attributor &A) : AANoUnwind(IRP, A) {}
const std::string getAsStr() const override {
return getAssumed() ? "nounwind" : "may-unwind";
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
auto Opcodes = {
(unsigned)Instruction::Invoke, (unsigned)Instruction::CallBr,
(unsigned)Instruction::Call, (unsigned)Instruction::CleanupRet,
(unsigned)Instruction::CatchSwitch, (unsigned)Instruction::Resume};
auto CheckForNoUnwind = [&](Instruction &I) {
if (!I.mayThrow())
return true;
if (const auto *CB = dyn_cast<CallBase>(&I)) {
const auto &NoUnwindAA =
A.getAAFor<AANoUnwind>(*this, IRPosition::callsite_function(*CB));
return NoUnwindAA.isAssumedNoUnwind();
}
return false;
};
if (!A.checkForAllInstructions(CheckForNoUnwind, *this, Opcodes))
return indicatePessimisticFixpoint();
return ChangeStatus::UNCHANGED;
}
};
struct AANoUnwindFunction final : public AANoUnwindImpl {
AANoUnwindFunction(const IRPosition &IRP, Attributor &A)
: AANoUnwindImpl(IRP, A) {}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_FN_ATTR(nounwind) }
};
/// NoUnwind attribute deduction for a call sites.
struct AANoUnwindCallSite final : AANoUnwindImpl {
AANoUnwindCallSite(const IRPosition &IRP, Attributor &A)
: AANoUnwindImpl(IRP, A) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
AANoUnwindImpl::initialize(A);
Function *F = getAssociatedFunction();
if (!F || F->isDeclaration())
indicatePessimisticFixpoint();
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
// TODO: Once we have call site specific value information we can provide
// call site specific liveness information and then it makes
// sense to specialize attributes for call sites arguments instead of
// redirecting requests to the callee argument.
Function *F = getAssociatedFunction();
const IRPosition &FnPos = IRPosition::function(*F);
auto &FnAA = A.getAAFor<AANoUnwind>(*this, FnPos);
return clampStateAndIndicateChange(getState(), FnAA.getState());
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_CS_ATTR(nounwind); }
};
/// --------------------- Function Return Values -------------------------------
/// "Attribute" that collects all potential returned values and the return
/// instructions that they arise from.
///
/// If there is a unique returned value R, the manifest method will:
/// - mark R with the "returned" attribute, if R is an argument.
class AAReturnedValuesImpl : public AAReturnedValues, public AbstractState {
/// Mapping of values potentially returned by the associated function to the
/// return instructions that might return them.
MapVector<Value *, SmallSetVector<ReturnInst *, 4>> ReturnedValues;
/// Mapping to remember the number of returned values for a call site such
/// that we can avoid updates if nothing changed.
DenseMap<const CallBase *, unsigned> NumReturnedValuesPerKnownAA;
/// Set of unresolved calls returned by the associated function.
SmallSetVector<CallBase *, 4> UnresolvedCalls;
/// State flags
///
///{
bool IsFixed = false;
bool IsValidState = true;
///}
public:
AAReturnedValuesImpl(const IRPosition &IRP, Attributor &A)
: AAReturnedValues(IRP, A) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
// Reset the state.
IsFixed = false;
IsValidState = true;
ReturnedValues.clear();
Function *F = getAssociatedFunction();
if (!F || F->isDeclaration()) {
indicatePessimisticFixpoint();
return;
}
assert(!F->getReturnType()->isVoidTy() &&
"Did not expect a void return type!");
// The map from instruction opcodes to those instructions in the function.
auto &OpcodeInstMap = A.getInfoCache().getOpcodeInstMapForFunction(*F);
// Look through all arguments, if one is marked as returned we are done.
for (Argument &Arg : F->args()) {
if (Arg.hasReturnedAttr()) {
auto &ReturnInstSet = ReturnedValues[&Arg];
if (auto *Insts = OpcodeInstMap.lookup(Instruction::Ret))
for (Instruction *RI : *Insts)
ReturnInstSet.insert(cast<ReturnInst>(RI));
indicateOptimisticFixpoint();
return;
}
}
if (!A.isFunctionIPOAmendable(*F))
indicatePessimisticFixpoint();
}
/// See AbstractAttribute::manifest(...).
ChangeStatus manifest(Attributor &A) override;
/// See AbstractAttribute::getState(...).
AbstractState &getState() override { return *this; }
/// See AbstractAttribute::getState(...).
const AbstractState &getState() const override { return *this; }
/// See AbstractAttribute::updateImpl(Attributor &A).
ChangeStatus updateImpl(Attributor &A) override;
llvm::iterator_range<iterator> returned_values() override {
return llvm::make_range(ReturnedValues.begin(), ReturnedValues.end());
}
llvm::iterator_range<const_iterator> returned_values() const override {
return llvm::make_range(ReturnedValues.begin(), ReturnedValues.end());
}
const SmallSetVector<CallBase *, 4> &getUnresolvedCalls() const override {
return UnresolvedCalls;
}
/// Return the number of potential return values, -1 if unknown.
size_t getNumReturnValues() const override {
return isValidState() ? ReturnedValues.size() : -1;
}
/// Return an assumed unique return value if a single candidate is found. If
/// there cannot be one, return a nullptr. If it is not clear yet, return the
/// Optional::NoneType.
Optional<Value *> getAssumedUniqueReturnValue(Attributor &A) const;
/// See AbstractState::checkForAllReturnedValues(...).
bool checkForAllReturnedValuesAndReturnInsts(
function_ref<bool(Value &, const SmallSetVector<ReturnInst *, 4> &)> Pred)
const override;
/// Pretty print the attribute similar to the IR representation.
const std::string getAsStr() const override;
/// See AbstractState::isAtFixpoint().
bool isAtFixpoint() const override { return IsFixed; }
/// See AbstractState::isValidState().
bool isValidState() const override { return IsValidState; }
/// See AbstractState::indicateOptimisticFixpoint(...).
ChangeStatus indicateOptimisticFixpoint() override {
IsFixed = true;
return ChangeStatus::UNCHANGED;
}
ChangeStatus indicatePessimisticFixpoint() override {
IsFixed = true;
IsValidState = false;
return ChangeStatus::CHANGED;
}
};
ChangeStatus AAReturnedValuesImpl::manifest(Attributor &A) {
ChangeStatus Changed = ChangeStatus::UNCHANGED;
// Bookkeeping.
assert(isValidState());
STATS_DECLTRACK(KnownReturnValues, FunctionReturn,
"Number of function with known return values");
// Check if we have an assumed unique return value that we could manifest.
Optional<Value *> UniqueRV = getAssumedUniqueReturnValue(A);
if (!UniqueRV.hasValue() || !UniqueRV.getValue())
return Changed;
// Bookkeeping.
STATS_DECLTRACK(UniqueReturnValue, FunctionReturn,
"Number of function with unique return");
// Callback to replace the uses of CB with the constant C.
auto ReplaceCallSiteUsersWith = [&A](CallBase &CB, Constant &C) {
if (CB.use_empty())
return ChangeStatus::UNCHANGED;
if (A.changeValueAfterManifest(CB, C))
return ChangeStatus::CHANGED;
return ChangeStatus::UNCHANGED;
};
// If the assumed unique return value is an argument, annotate it.
if (auto *UniqueRVArg = dyn_cast<Argument>(UniqueRV.getValue())) {
if (UniqueRVArg->getType()->canLosslesslyBitCastTo(
getAssociatedFunction()->getReturnType())) {
getIRPosition() = IRPosition::argument(*UniqueRVArg);
Changed = IRAttribute::manifest(A);
}
} else if (auto *RVC = dyn_cast<Constant>(UniqueRV.getValue())) {
// We can replace the returned value with the unique returned constant.
Value &AnchorValue = getAnchorValue();
if (Function *F = dyn_cast<Function>(&AnchorValue)) {
for (const Use &U : F->uses())
if (CallBase *CB = dyn_cast<CallBase>(U.getUser()))
if (CB->isCallee(&U)) {
Constant *RVCCast =
CB->getType() == RVC->getType()
? RVC
: ConstantExpr::getTruncOrBitCast(RVC, CB->getType());
Changed = ReplaceCallSiteUsersWith(*CB, *RVCCast) | Changed;
}
} else {
assert(isa<CallBase>(AnchorValue) &&
"Expcected a function or call base anchor!");
Constant *RVCCast =
AnchorValue.getType() == RVC->getType()
? RVC
: ConstantExpr::getTruncOrBitCast(RVC, AnchorValue.getType());
Changed = ReplaceCallSiteUsersWith(cast<CallBase>(AnchorValue), *RVCCast);
}
if (Changed == ChangeStatus::CHANGED)
STATS_DECLTRACK(UniqueConstantReturnValue, FunctionReturn,
"Number of function returns replaced by constant return");
}
return Changed;
}
const std::string AAReturnedValuesImpl::getAsStr() const {
return (isAtFixpoint() ? "returns(#" : "may-return(#") +
(isValidState() ? std::to_string(getNumReturnValues()) : "?") +
")[#UC: " + std::to_string(UnresolvedCalls.size()) + "]";
}
Optional<Value *>
AAReturnedValuesImpl::getAssumedUniqueReturnValue(Attributor &A) const {
// If checkForAllReturnedValues provides a unique value, ignoring potential
// undef values that can also be present, it is assumed to be the actual
// return value and forwarded to the caller of this method. If there are
// multiple, a nullptr is returned indicating there cannot be a unique
// returned value.
Optional<Value *> UniqueRV;
auto Pred = [&](Value &RV) -> bool {
// If we found a second returned value and neither the current nor the saved
// one is an undef, there is no unique returned value. Undefs are special
// since we can pretend they have any value.
if (UniqueRV.hasValue() && UniqueRV != &RV &&
!(isa<UndefValue>(RV) || isa<UndefValue>(UniqueRV.getValue()))) {
UniqueRV = nullptr;
return false;
}
// Do not overwrite a value with an undef.
if (!UniqueRV.hasValue() || !isa<UndefValue>(RV))
UniqueRV = &RV;
return true;
};
if (!A.checkForAllReturnedValues(Pred, *this))
UniqueRV = nullptr;
return UniqueRV;
}
bool AAReturnedValuesImpl::checkForAllReturnedValuesAndReturnInsts(
function_ref<bool(Value &, const SmallSetVector<ReturnInst *, 4> &)> Pred)
const {
if (!isValidState())
return false;
// Check all returned values but ignore call sites as long as we have not
// encountered an overdefined one during an update.
for (auto &It : ReturnedValues) {
Value *RV = It.first;
CallBase *CB = dyn_cast<CallBase>(RV);
if (CB && !UnresolvedCalls.count(CB))
continue;
if (!Pred(*RV, It.second))
return false;
}
return true;
}
ChangeStatus AAReturnedValuesImpl::updateImpl(Attributor &A) {
size_t NumUnresolvedCalls = UnresolvedCalls.size();
bool Changed = false;
// State used in the value traversals starting in returned values.
struct RVState {
// The map in which we collect return values -> return instrs.
decltype(ReturnedValues) &RetValsMap;
// The flag to indicate a change.
bool &Changed;
// The return instrs we come from.
SmallSetVector<ReturnInst *, 4> RetInsts;
};
// Callback for a leaf value returned by the associated function.
auto VisitValueCB = [](Value &Val, const Instruction *, RVState &RVS,
bool) -> bool {
auto Size = RVS.RetValsMap[&Val].size();
RVS.RetValsMap[&Val].insert(RVS.RetInsts.begin(), RVS.RetInsts.end());
bool Inserted = RVS.RetValsMap[&Val].size() != Size;
RVS.Changed |= Inserted;
LLVM_DEBUG({
if (Inserted)
dbgs() << "[AAReturnedValues] 1 Add new returned value " << Val
<< " => " << RVS.RetInsts.size() << "\n";
});
return true;
};
// Helper method to invoke the generic value traversal.
auto VisitReturnedValue = [&](Value &RV, RVState &RVS,
const Instruction *CtxI) {
IRPosition RetValPos = IRPosition::value(RV);
return genericValueTraversal<AAReturnedValues, RVState>(
A, RetValPos, *this, RVS, VisitValueCB, CtxI,
/* UseValueSimplify */ false);
};
// Callback for all "return intructions" live in the associated function.
auto CheckReturnInst = [this, &VisitReturnedValue, &Changed](Instruction &I) {
ReturnInst &Ret = cast<ReturnInst>(I);
RVState RVS({ReturnedValues, Changed, {}});
RVS.RetInsts.insert(&Ret);
return VisitReturnedValue(*Ret.getReturnValue(), RVS, &I);
};
// Start by discovering returned values from all live returned instructions in
// the associated function.
if (!A.checkForAllInstructions(CheckReturnInst, *this, {Instruction::Ret}))
return indicatePessimisticFixpoint();
// Once returned values "directly" present in the code are handled we try to
// resolve returned calls. To avoid modifications to the ReturnedValues map
// while we iterate over it we kept record of potential new entries in a copy
// map, NewRVsMap.
decltype(ReturnedValues) NewRVsMap;
auto HandleReturnValue = [&](Value *RV,
SmallSetVector<ReturnInst *, 4> &RIs) {
LLVM_DEBUG(dbgs() << "[AAReturnedValues] Returned value: " << *RV << " by #"
<< RIs.size() << " RIs\n");
CallBase *CB = dyn_cast<CallBase>(RV);
if (!CB || UnresolvedCalls.count(CB))
return;
if (!CB->getCalledFunction()) {
LLVM_DEBUG(dbgs() << "[AAReturnedValues] Unresolved call: " << *CB
<< "\n");
UnresolvedCalls.insert(CB);
return;
}
// TODO: use the function scope once we have call site AAReturnedValues.
const auto &RetValAA = A.getAAFor<AAReturnedValues>(
*this, IRPosition::function(*CB->getCalledFunction()));
LLVM_DEBUG(dbgs() << "[AAReturnedValues] Found another AAReturnedValues: "
<< RetValAA << "\n");
// Skip dead ends, thus if we do not know anything about the returned
// call we mark it as unresolved and it will stay that way.
if (!RetValAA.getState().isValidState()) {
LLVM_DEBUG(dbgs() << "[AAReturnedValues] Unresolved call: " << *CB
<< "\n");
UnresolvedCalls.insert(CB);
return;
}
// Do not try to learn partial information. If the callee has unresolved
// return values we will treat the call as unresolved/opaque.
auto &RetValAAUnresolvedCalls = RetValAA.getUnresolvedCalls();
if (!RetValAAUnresolvedCalls.empty()) {
UnresolvedCalls.insert(CB);
return;
}
// Now check if we can track transitively returned values. If possible, thus
// if all return value can be represented in the current scope, do so.
bool Unresolved = false;
for (auto &RetValAAIt : RetValAA.returned_values()) {
Value *RetVal = RetValAAIt.first;
if (isa<Argument>(RetVal) || isa<CallBase>(RetVal) ||
isa<Constant>(RetVal))
continue;
// Anything that did not fit in the above categories cannot be resolved,
// mark the call as unresolved.
LLVM_DEBUG(dbgs() << "[AAReturnedValues] transitively returned value "
"cannot be translated: "
<< *RetVal << "\n");
UnresolvedCalls.insert(CB);
Unresolved = true;
break;
}
if (Unresolved)
return;
// Now track transitively returned values.
unsigned &NumRetAA = NumReturnedValuesPerKnownAA[CB];
if (NumRetAA == RetValAA.getNumReturnValues()) {
LLVM_DEBUG(dbgs() << "[AAReturnedValues] Skip call as it has not "
"changed since it was seen last\n");
return;
}
NumRetAA = RetValAA.getNumReturnValues();
for (auto &RetValAAIt : RetValAA.returned_values()) {
Value *RetVal = RetValAAIt.first;
if (Argument *Arg = dyn_cast<Argument>(RetVal)) {
// Arguments are mapped to call site operands and we begin the traversal
// again.
bool Unused = false;
RVState RVS({NewRVsMap, Unused, RetValAAIt.second});
VisitReturnedValue(*CB->getArgOperand(Arg->getArgNo()), RVS, CB);
continue;
}
if (isa<CallBase>(RetVal)) {
// Call sites are resolved by the callee attribute over time, no need to
// do anything for us.
continue;
}
if (isa<Constant>(RetVal)) {
// Constants are valid everywhere, we can simply take them.
NewRVsMap[RetVal].insert(RIs.begin(), RIs.end());
continue;
}
}
};
for (auto &It : ReturnedValues)
HandleReturnValue(It.first, It.second);
// Because processing the new information can again lead to new return values
// we have to be careful and iterate until this iteration is complete. The
// idea is that we are in a stable state at the end of an update. All return
// values have been handled and properly categorized. We might not update
// again if we have not requested a non-fix attribute so we cannot "wait" for
// the next update to analyze a new return value.
while (!NewRVsMap.empty()) {
auto It = std::move(NewRVsMap.back());
NewRVsMap.pop_back();
assert(!It.second.empty() && "Entry does not add anything.");
auto &ReturnInsts = ReturnedValues[It.first];
for (ReturnInst *RI : It.second)
if (ReturnInsts.insert(RI)) {
LLVM_DEBUG(dbgs() << "[AAReturnedValues] Add new returned value "
<< *It.first << " => " << *RI << "\n");
HandleReturnValue(It.first, ReturnInsts);
Changed = true;
}
}
Changed |= (NumUnresolvedCalls != UnresolvedCalls.size());
return Changed ? ChangeStatus::CHANGED : ChangeStatus::UNCHANGED;
}
struct AAReturnedValuesFunction final : public AAReturnedValuesImpl {
AAReturnedValuesFunction(const IRPosition &IRP, Attributor &A)
: AAReturnedValuesImpl(IRP, A) {}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_ARG_ATTR(returned) }
};
/// Returned values information for a call sites.
struct AAReturnedValuesCallSite final : AAReturnedValuesImpl {
AAReturnedValuesCallSite(const IRPosition &IRP, Attributor &A)
: AAReturnedValuesImpl(IRP, A) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
// TODO: Once we have call site specific value information we can provide
// call site specific liveness information and then it makes
// sense to specialize attributes for call sites instead of
// redirecting requests to the callee.
llvm_unreachable("Abstract attributes for returned values are not "
"supported for call sites yet!");
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
return indicatePessimisticFixpoint();
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {}
};
/// ------------------------ NoSync Function Attribute -------------------------
struct AANoSyncImpl : AANoSync {
AANoSyncImpl(const IRPosition &IRP, Attributor &A) : AANoSync(IRP, A) {}
const std::string getAsStr() const override {
return getAssumed() ? "nosync" : "may-sync";
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override;
/// Helper function used to determine whether an instruction is non-relaxed
/// atomic. In other words, if an atomic instruction does not have unordered
/// or monotonic ordering
static bool isNonRelaxedAtomic(Instruction *I);
/// Helper function used to determine whether an instruction is volatile.
static bool isVolatile(Instruction *I);
/// Helper function uset to check if intrinsic is volatile (memcpy, memmove,
/// memset).
static bool isNoSyncIntrinsic(Instruction *I);
};
bool AANoSyncImpl::isNonRelaxedAtomic(Instruction *I) {
if (!I->isAtomic())
return false;
AtomicOrdering Ordering;
switch (I->getOpcode()) {
case Instruction::AtomicRMW:
Ordering = cast<AtomicRMWInst>(I)->getOrdering();
break;
case Instruction::Store:
Ordering = cast<StoreInst>(I)->getOrdering();
break;
case Instruction::Load:
Ordering = cast<LoadInst>(I)->getOrdering();
break;
case Instruction::Fence: {
auto *FI = cast<FenceInst>(I);
if (FI->getSyncScopeID() == SyncScope::SingleThread)
return false;
Ordering = FI->getOrdering();
break;
}
case Instruction::AtomicCmpXchg: {
AtomicOrdering Success = cast<AtomicCmpXchgInst>(I)->getSuccessOrdering();
AtomicOrdering Failure = cast<AtomicCmpXchgInst>(I)->getFailureOrdering();
// Only if both are relaxed, than it can be treated as relaxed.
// Otherwise it is non-relaxed.
if (Success != AtomicOrdering::Unordered &&
Success != AtomicOrdering::Monotonic)
return true;
if (Failure != AtomicOrdering::Unordered &&
Failure != AtomicOrdering::Monotonic)
return true;
return false;
}
default:
llvm_unreachable(
"New atomic operations need to be known in the attributor.");
}
// Relaxed.
if (Ordering == AtomicOrdering::Unordered ||
Ordering == AtomicOrdering::Monotonic)
return false;
return true;
}
/// Checks if an intrinsic is nosync. Currently only checks mem* intrinsics.
/// FIXME: We should ipmrove the handling of intrinsics.
bool AANoSyncImpl::isNoSyncIntrinsic(Instruction *I) {
if (auto *II = dyn_cast<IntrinsicInst>(I)) {
switch (II->getIntrinsicID()) {
/// Element wise atomic memory intrinsics are can only be unordered,
/// therefore nosync.
case Intrinsic::memset_element_unordered_atomic:
case Intrinsic::memmove_element_unordered_atomic:
case Intrinsic::memcpy_element_unordered_atomic:
return true;
case Intrinsic::memset:
case Intrinsic::memmove:
case Intrinsic::memcpy:
if (!cast<MemIntrinsic>(II)->isVolatile())
return true;
return false;
default:
return false;
}
}
return false;
}
bool AANoSyncImpl::isVolatile(Instruction *I) {
assert(!isa<CallBase>(I) && "Calls should not be checked here");
switch (I->getOpcode()) {
case Instruction::AtomicRMW:
return cast<AtomicRMWInst>(I)->isVolatile();
case Instruction::Store:
return cast<StoreInst>(I)->isVolatile();
case Instruction::Load:
return cast<LoadInst>(I)->isVolatile();
case Instruction::AtomicCmpXchg:
return cast<AtomicCmpXchgInst>(I)->isVolatile();
default:
return false;
}
}
ChangeStatus AANoSyncImpl::updateImpl(Attributor &A) {
auto CheckRWInstForNoSync = [&](Instruction &I) {
/// We are looking for volatile instructions or Non-Relaxed atomics.
/// FIXME: We should improve the handling of intrinsics.
if (isa<IntrinsicInst>(&I) && isNoSyncIntrinsic(&I))
return true;
if (const auto *CB = dyn_cast<CallBase>(&I)) {
if (CB->hasFnAttr(Attribute::NoSync))
return true;
const auto &NoSyncAA =
A.getAAFor<AANoSync>(*this, IRPosition::callsite_function(*CB));
if (NoSyncAA.isAssumedNoSync())
return true;
return false;
}
if (!isVolatile(&I) && !isNonRelaxedAtomic(&I))
return true;
return false;
};
auto CheckForNoSync = [&](Instruction &I) {
// At this point we handled all read/write effects and they are all
// nosync, so they can be skipped.
if (I.mayReadOrWriteMemory())
return true;
// non-convergent and readnone imply nosync.
return !cast<CallBase>(I).isConvergent();
};
if (!A.checkForAllReadWriteInstructions(CheckRWInstForNoSync, *this) ||
!A.checkForAllCallLikeInstructions(CheckForNoSync, *this))
return indicatePessimisticFixpoint();
return ChangeStatus::UNCHANGED;
}
struct AANoSyncFunction final : public AANoSyncImpl {
AANoSyncFunction(const IRPosition &IRP, Attributor &A)
: AANoSyncImpl(IRP, A) {}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_FN_ATTR(nosync) }
};
/// NoSync attribute deduction for a call sites.
struct AANoSyncCallSite final : AANoSyncImpl {
AANoSyncCallSite(const IRPosition &IRP, Attributor &A)
: AANoSyncImpl(IRP, A) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
AANoSyncImpl::initialize(A);
Function *F = getAssociatedFunction();
if (!F || F->isDeclaration())
indicatePessimisticFixpoint();
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
// TODO: Once we have call site specific value information we can provide
// call site specific liveness information and then it makes
// sense to specialize attributes for call sites arguments instead of
// redirecting requests to the callee argument.
Function *F = getAssociatedFunction();
const IRPosition &FnPos = IRPosition::function(*F);
auto &FnAA = A.getAAFor<AANoSync>(*this, FnPos);
return clampStateAndIndicateChange(getState(), FnAA.getState());
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_CS_ATTR(nosync); }
};
/// ------------------------ No-Free Attributes ----------------------------
struct AANoFreeImpl : public AANoFree {
AANoFreeImpl(const IRPosition &IRP, Attributor &A) : AANoFree(IRP, A) {}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
auto CheckForNoFree = [&](Instruction &I) {
const auto &CB = cast<CallBase>(I);
if (CB.hasFnAttr(Attribute::NoFree))
return true;
const auto &NoFreeAA =
A.getAAFor<AANoFree>(*this, IRPosition::callsite_function(CB));
return NoFreeAA.isAssumedNoFree();
};
if (!A.checkForAllCallLikeInstructions(CheckForNoFree, *this))
return indicatePessimisticFixpoint();
return ChangeStatus::UNCHANGED;
}
/// See AbstractAttribute::getAsStr().
const std::string getAsStr() const override {
return getAssumed() ? "nofree" : "may-free";
}
};
struct AANoFreeFunction final : public AANoFreeImpl {
AANoFreeFunction(const IRPosition &IRP, Attributor &A)
: AANoFreeImpl(IRP, A) {}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_FN_ATTR(nofree) }
};
/// NoFree attribute deduction for a call sites.
struct AANoFreeCallSite final : AANoFreeImpl {
AANoFreeCallSite(const IRPosition &IRP, Attributor &A)
: AANoFreeImpl(IRP, A) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
AANoFreeImpl::initialize(A);
Function *F = getAssociatedFunction();
if (!F || F->isDeclaration())
indicatePessimisticFixpoint();
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
// TODO: Once we have call site specific value information we can provide
// call site specific liveness information and then it makes
// sense to specialize attributes for call sites arguments instead of
// redirecting requests to the callee argument.
Function *F = getAssociatedFunction();
const IRPosition &FnPos = IRPosition::function(*F);
auto &FnAA = A.getAAFor<AANoFree>(*this, FnPos);
return clampStateAndIndicateChange(getState(), FnAA.getState());
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_CS_ATTR(nofree); }
};
/// NoFree attribute for floating values.
struct AANoFreeFloating : AANoFreeImpl {
AANoFreeFloating(const IRPosition &IRP, Attributor &A)
: AANoFreeImpl(IRP, A) {}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override{STATS_DECLTRACK_FLOATING_ATTR(nofree)}
/// See Abstract Attribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
const IRPosition &IRP = getIRPosition();
const auto &NoFreeAA =
A.getAAFor<AANoFree>(*this, IRPosition::function_scope(IRP));
if (NoFreeAA.isAssumedNoFree())
return ChangeStatus::UNCHANGED;
Value &AssociatedValue = getIRPosition().getAssociatedValue();
auto Pred = [&](const Use &U, bool &Follow) -> bool {
Instruction *UserI = cast<Instruction>(U.getUser());
if (auto *CB = dyn_cast<CallBase>(UserI)) {
if (CB->isBundleOperand(&U))
return false;
if (!CB->isArgOperand(&U))
return true;
unsigned ArgNo = CB->getArgOperandNo(&U);
const auto &NoFreeArg = A.getAAFor<AANoFree>(
*this, IRPosition::callsite_argument(*CB, ArgNo));
return NoFreeArg.isAssumedNoFree();
}
if (isa<GetElementPtrInst>(UserI) || isa<BitCastInst>(UserI) ||
isa<PHINode>(UserI) || isa<SelectInst>(UserI)) {
Follow = true;
return true;
}
if (isa<ReturnInst>(UserI))
return true;
// Unknown user.
return false;
};
if (!A.checkForAllUses(Pred, *this, AssociatedValue))
return indicatePessimisticFixpoint();
return ChangeStatus::UNCHANGED;
}
};
/// NoFree attribute for a call site argument.
struct AANoFreeArgument final : AANoFreeFloating {
AANoFreeArgument(const IRPosition &IRP, Attributor &A)
: AANoFreeFloating(IRP, A) {}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_ARG_ATTR(nofree) }
};
/// NoFree attribute for call site arguments.
struct AANoFreeCallSiteArgument final : AANoFreeFloating {
AANoFreeCallSiteArgument(const IRPosition &IRP, Attributor &A)
: AANoFreeFloating(IRP, A) {}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
// TODO: Once we have call site specific value information we can provide
// call site specific liveness information and then it makes
// sense to specialize attributes for call sites arguments instead of
// redirecting requests to the callee argument.
Argument *Arg = getAssociatedArgument();
if (!Arg)
return indicatePessimisticFixpoint();
const IRPosition &ArgPos = IRPosition::argument(*Arg);
auto &ArgAA = A.getAAFor<AANoFree>(*this, ArgPos);
return clampStateAndIndicateChange(getState(), ArgAA.getState());
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override{STATS_DECLTRACK_CSARG_ATTR(nofree)};
};
/// NoFree attribute for function return value.
struct AANoFreeReturned final : AANoFreeFloating {
AANoFreeReturned(const IRPosition &IRP, Attributor &A)
: AANoFreeFloating(IRP, A) {
llvm_unreachable("NoFree is not applicable to function returns!");
}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
llvm_unreachable("NoFree is not applicable to function returns!");
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
llvm_unreachable("NoFree is not applicable to function returns!");
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {}
};
/// NoFree attribute deduction for a call site return value.
struct AANoFreeCallSiteReturned final : AANoFreeFloating {
AANoFreeCallSiteReturned(const IRPosition &IRP, Attributor &A)
: AANoFreeFloating(IRP, A) {}
ChangeStatus manifest(Attributor &A) override {
return ChangeStatus::UNCHANGED;
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_CSRET_ATTR(nofree) }
};
/// ------------------------ NonNull Argument Attribute ------------------------
static int64_t getKnownNonNullAndDerefBytesForUse(
Attributor &A, const AbstractAttribute &QueryingAA, Value &AssociatedValue,
const Use *U, const Instruction *I, bool &IsNonNull, bool &TrackUse) {
TrackUse = false;
const Value *UseV = U->get();
if (!UseV->getType()->isPointerTy())
return 0;
Type *PtrTy = UseV->getType();
const Function *F = I->getFunction();
bool NullPointerIsDefined =
F ? llvm::NullPointerIsDefined(F, PtrTy->getPointerAddressSpace()) : true;
const DataLayout &DL = A.getInfoCache().getDL();
if (const auto *CB = dyn_cast<CallBase>(I)) {
if (CB->isBundleOperand(U)) {
if (RetainedKnowledge RK = getKnowledgeFromUse(
U, {Attribute::NonNull, Attribute::Dereferenceable})) {
IsNonNull |=
(RK.AttrKind == Attribute::NonNull || !NullPointerIsDefined);
return RK.ArgValue;
}
return 0;
}
if (CB->isCallee(U)) {
IsNonNull |= !NullPointerIsDefined;
return 0;
}
unsigned ArgNo = CB->getArgOperandNo(U);
IRPosition IRP = IRPosition::callsite_argument(*CB, ArgNo);
// As long as we only use known information there is no need to track
// dependences here.
auto &DerefAA = A.getAAFor<AADereferenceable>(QueryingAA, IRP,
/* TrackDependence */ false);
IsNonNull |= DerefAA.isKnownNonNull();
return DerefAA.getKnownDereferenceableBytes();
}
// We need to follow common pointer manipulation uses to the accesses they
// feed into. We can try to be smart to avoid looking through things we do not
// like for now, e.g., non-inbounds GEPs.
if (isa<CastInst>(I)) {
TrackUse = true;
return 0;
}
if (isa<GetElementPtrInst>(I)) {
TrackUse = true;
return 0;
}
int64_t Offset;
const Value *Base =
getMinimalBaseOfAccsesPointerOperand(A, QueryingAA, I, Offset, DL);
if (Base) {
if (Base == &AssociatedValue &&
getPointerOperand(I, /* AllowVolatile */ false) == UseV) {
int64_t DerefBytes =
(int64_t)DL.getTypeStoreSize(PtrTy->getPointerElementType()) + Offset;
IsNonNull |= !NullPointerIsDefined;
return std::max(int64_t(0), DerefBytes);
}
}
/// Corner case when an offset is 0.
Base = getBasePointerOfAccessPointerOperand(I, Offset, DL,
/*AllowNonInbounds*/ true);
if (Base) {
if (Offset == 0 && Base == &AssociatedValue &&
getPointerOperand(I, /* AllowVolatile */ false) == UseV) {
int64_t DerefBytes =
(int64_t)DL.getTypeStoreSize(PtrTy->getPointerElementType());
IsNonNull |= !NullPointerIsDefined;
return std::max(int64_t(0), DerefBytes);
}
}
return 0;
}
struct AANonNullImpl : AANonNull {
AANonNullImpl(const IRPosition &IRP, Attributor &A)
: AANonNull(IRP, A),
NullIsDefined(NullPointerIsDefined(
getAnchorScope(),
getAssociatedValue().getType()->getPointerAddressSpace())) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
Value &V = getAssociatedValue();
if (!NullIsDefined &&
hasAttr({Attribute::NonNull, Attribute::Dereferenceable},
/* IgnoreSubsumingPositions */ false, &A)) {
indicateOptimisticFixpoint();
return;
}
if (isa<ConstantPointerNull>(V)) {
indicatePessimisticFixpoint();
return;
}
AANonNull::initialize(A);
bool CanBeNull = true;
if (V.getPointerDereferenceableBytes(A.getDataLayout(), CanBeNull)) {
if (!CanBeNull) {
indicateOptimisticFixpoint();
return;
}
}
if (isa<GlobalValue>(&getAssociatedValue())) {
indicatePessimisticFixpoint();
return;
}
if (Instruction *CtxI = getCtxI())
followUsesInMBEC(*this, A, getState(), *CtxI);
}
/// See followUsesInMBEC
bool followUseInMBEC(Attributor &A, const Use *U, const Instruction *I,
AANonNull::StateType &State) {
bool IsNonNull = false;
bool TrackUse = false;
getKnownNonNullAndDerefBytesForUse(A, *this, getAssociatedValue(), U, I,
IsNonNull, TrackUse);
State.setKnown(IsNonNull);
return TrackUse;
}
/// See AbstractAttribute::getAsStr().
const std::string getAsStr() const override {
return getAssumed() ? "nonnull" : "may-null";
}
/// Flag to determine if the underlying value can be null and still allow
/// valid accesses.
const bool NullIsDefined;
};
/// NonNull attribute for a floating value.
struct AANonNullFloating : public AANonNullImpl {
AANonNullFloating(const IRPosition &IRP, Attributor &A)
: AANonNullImpl(IRP, A) {}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
const DataLayout &DL = A.getDataLayout();
DominatorTree *DT = nullptr;
AssumptionCache *AC = nullptr;
InformationCache &InfoCache = A.getInfoCache();
if (const Function *Fn = getAnchorScope()) {
DT = InfoCache.getAnalysisResultForFunction<DominatorTreeAnalysis>(*Fn);
AC = InfoCache.getAnalysisResultForFunction<AssumptionAnalysis>(*Fn);
}
auto VisitValueCB = [&](Value &V, const Instruction *CtxI,
AANonNull::StateType &T, bool Stripped) -> bool {
const auto &AA = A.getAAFor<AANonNull>(*this, IRPosition::value(V));
if (!Stripped && this == &AA) {
if (!isKnownNonZero(&V, DL, 0, AC, CtxI, DT))
T.indicatePessimisticFixpoint();
} else {
// Use abstract attribute information.
const AANonNull::StateType &NS = AA.getState();
T ^= NS;
}
return T.isValidState();
};
StateType T;
if (!genericValueTraversal<AANonNull, StateType>(
A, getIRPosition(), *this, T, VisitValueCB, getCtxI()))
return indicatePessimisticFixpoint();
return clampStateAndIndicateChange(getState(), T);
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_FNRET_ATTR(nonnull) }
};
/// NonNull attribute for function return value.
struct AANonNullReturned final
: AAReturnedFromReturnedValues<AANonNull, AANonNull> {
AANonNullReturned(const IRPosition &IRP, Attributor &A)
: AAReturnedFromReturnedValues<AANonNull, AANonNull>(IRP, A) {}
/// See AbstractAttribute::getAsStr().
const std::string getAsStr() const override {
return getAssumed() ? "nonnull" : "may-null";
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_FNRET_ATTR(nonnull) }
};
/// NonNull attribute for function argument.
struct AANonNullArgument final
: AAArgumentFromCallSiteArguments<AANonNull, AANonNullImpl> {
AANonNullArgument(const IRPosition &IRP, Attributor &A)
: AAArgumentFromCallSiteArguments<AANonNull, AANonNullImpl>(IRP, A) {}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_ARG_ATTR(nonnull) }
};
struct AANonNullCallSiteArgument final : AANonNullFloating {
AANonNullCallSiteArgument(const IRPosition &IRP, Attributor &A)
: AANonNullFloating(IRP, A) {}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_CSARG_ATTR(nonnull) }
};
/// NonNull attribute for a call site return position.
struct AANonNullCallSiteReturned final
: AACallSiteReturnedFromReturned<AANonNull, AANonNullImpl> {
AANonNullCallSiteReturned(const IRPosition &IRP, Attributor &A)
: AACallSiteReturnedFromReturned<AANonNull, AANonNullImpl>(IRP, A) {}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_CSRET_ATTR(nonnull) }
};
/// ------------------------ No-Recurse Attributes ----------------------------
struct AANoRecurseImpl : public AANoRecurse {
AANoRecurseImpl(const IRPosition &IRP, Attributor &A) : AANoRecurse(IRP, A) {}
/// See AbstractAttribute::getAsStr()
const std::string getAsStr() const override {
return getAssumed() ? "norecurse" : "may-recurse";
}
};
struct AANoRecurseFunction final : AANoRecurseImpl {
AANoRecurseFunction(const IRPosition &IRP, Attributor &A)
: AANoRecurseImpl(IRP, A) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
AANoRecurseImpl::initialize(A);
if (const Function *F = getAnchorScope())
if (A.getInfoCache().getSccSize(*F) != 1)
indicatePessimisticFixpoint();
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
// If all live call sites are known to be no-recurse, we are as well.
auto CallSitePred = [&](AbstractCallSite ACS) {
const auto &NoRecurseAA = A.getAAFor<AANoRecurse>(
*this, IRPosition::function(*ACS.getInstruction()->getFunction()),
/* TrackDependence */ false, DepClassTy::OPTIONAL);
return NoRecurseAA.isKnownNoRecurse();
};
bool AllCallSitesKnown;
if (A.checkForAllCallSites(CallSitePred, *this, true, AllCallSitesKnown)) {
// If we know all call sites and all are known no-recurse, we are done.
// If all known call sites, which might not be all that exist, are known
// to be no-recurse, we are not done but we can continue to assume
// no-recurse. If one of the call sites we have not visited will become
// live, another update is triggered.
if (AllCallSitesKnown)
indicateOptimisticFixpoint();
return ChangeStatus::UNCHANGED;
}
// If the above check does not hold anymore we look at the calls.
auto CheckForNoRecurse = [&](Instruction &I) {
const auto &CB = cast<CallBase>(I);
if (CB.hasFnAttr(Attribute::NoRecurse))
return true;
const auto &NoRecurseAA =
A.getAAFor<AANoRecurse>(*this, IRPosition::callsite_function(CB));
if (!NoRecurseAA.isAssumedNoRecurse())
return false;
// Recursion to the same function
if (CB.getCalledFunction() == getAnchorScope())
return false;
return true;
};
if (!A.checkForAllCallLikeInstructions(CheckForNoRecurse, *this))
return indicatePessimisticFixpoint();
return ChangeStatus::UNCHANGED;
}
void trackStatistics() const override { STATS_DECLTRACK_FN_ATTR(norecurse) }
};
/// NoRecurse attribute deduction for a call sites.
struct AANoRecurseCallSite final : AANoRecurseImpl {
AANoRecurseCallSite(const IRPosition &IRP, Attributor &A)
: AANoRecurseImpl(IRP, A) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
AANoRecurseImpl::initialize(A);
Function *F = getAssociatedFunction();
if (!F || F->isDeclaration())
indicatePessimisticFixpoint();
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
// TODO: Once we have call site specific value information we can provide
// call site specific liveness information and then it makes
// sense to specialize attributes for call sites arguments instead of
// redirecting requests to the callee argument.
Function *F = getAssociatedFunction();
const IRPosition &FnPos = IRPosition::function(*F);
auto &FnAA = A.getAAFor<AANoRecurse>(*this, FnPos);
return clampStateAndIndicateChange(getState(), FnAA.getState());
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_CS_ATTR(norecurse); }
};
/// -------------------- Undefined-Behavior Attributes ------------------------
struct AAUndefinedBehaviorImpl : public AAUndefinedBehavior {
AAUndefinedBehaviorImpl(const IRPosition &IRP, Attributor &A)
: AAUndefinedBehavior(IRP, A) {}
/// See AbstractAttribute::updateImpl(...).
// through a pointer (i.e. also branches etc.)
ChangeStatus updateImpl(Attributor &A) override {
const size_t UBPrevSize = KnownUBInsts.size();
const size_t NoUBPrevSize = AssumedNoUBInsts.size();
auto InspectMemAccessInstForUB = [&](Instruction &I) {
// Skip instructions that are already saved.
if (AssumedNoUBInsts.count(&I) || KnownUBInsts.count(&I))
return true;
// If we reach here, we know we have an instruction
// that accesses memory through a pointer operand,
// for which getPointerOperand() should give it to us.
const Value *PtrOp = getPointerOperand(&I, /* AllowVolatile */ true);
assert(PtrOp &&
"Expected pointer operand of memory accessing instruction");
// Either we stopped and the appropriate action was taken,
// or we got back a simplified value to continue.
Optional<Value *> SimplifiedPtrOp = stopOnUndefOrAssumed(A, PtrOp, &I);
if (!SimplifiedPtrOp.hasValue())
return true;
const Value *PtrOpVal = SimplifiedPtrOp.getValue();
// A memory access through a pointer is considered UB
// only if the pointer has constant null value.
// TODO: Expand it to not only check constant values.
if (!isa<ConstantPointerNull>(PtrOpVal)) {
AssumedNoUBInsts.insert(&I);
return true;
}
const Type *PtrTy = PtrOpVal->getType();
// Because we only consider instructions inside functions,
// assume that a parent function exists.
const Function *F = I.getFunction();
// A memory access using constant null pointer is only considered UB
// if null pointer is _not_ defined for the target platform.
if (llvm::NullPointerIsDefined(F, PtrTy->getPointerAddressSpace()))
AssumedNoUBInsts.insert(&I);
else
KnownUBInsts.insert(&I);
return true;
};
auto InspectBrInstForUB = [&](Instruction &I) {
// A conditional branch instruction is considered UB if it has `undef`
// condition.
// Skip instructions that are already saved.
if (AssumedNoUBInsts.count(&I) || KnownUBInsts.count(&I))
return true;
// We know we have a branch instruction.
auto BrInst = cast<BranchInst>(&I);
// Unconditional branches are never considered UB.
if (BrInst->isUnconditional())
return true;
// Either we stopped and the appropriate action was taken,
// or we got back a simplified value to continue.
Optional<Value *> SimplifiedCond =
stopOnUndefOrAssumed(A, BrInst->getCondition(), BrInst);
if (!SimplifiedCond.hasValue())
return true;
AssumedNoUBInsts.insert(&I);
return true;
};
auto InspectCallSiteForUB = [&](Instruction &I) {
// Check whether a callsite always cause UB or not
// Skip instructions that are already saved.
if (AssumedNoUBInsts.count(&I) || KnownUBInsts.count(&I))
return true;
// Check nonnull and noundef argument attribute violation for each
// callsite.
CallBase &CB = cast<CallBase>(I);
Function *Callee = CB.getCalledFunction();
if (!Callee)
return true;
for (unsigned idx = 0; idx < CB.getNumArgOperands(); idx++) {
// If current argument is known to be simplified to null pointer and the
// corresponding argument position is known to have nonnull attribute,
// the argument is poison. Furthermore, if the argument is poison and
// the position is known to have noundef attriubte, this callsite is
// considered UB.
if (idx >= Callee->arg_size())
break;
Value *ArgVal = CB.getArgOperand(idx);
if (!ArgVal)
continue;
// Here, we handle three cases.
// (1) Not having a value means it is dead. (we can replace the value
// with undef)
// (2) Simplified to undef. The argument violate noundef attriubte.
// (3) Simplified to null pointer where known to be nonnull.
// The argument is a poison value and violate noundef attribute.
IRPosition CalleeArgumentIRP = IRPosition::callsite_argument(CB, idx);
auto &NoUndefAA = A.getAAFor<AANoUndef>(*this, CalleeArgumentIRP,
/* TrackDependence */ false);
if (!NoUndefAA.isKnownNoUndef())
continue;
auto &ValueSimplifyAA = A.getAAFor<AAValueSimplify>(
*this, IRPosition::value(*ArgVal), /* TrackDependence */ false);
if (!ValueSimplifyAA.isKnown())
continue;
Optional<Value *> SimplifiedVal =
ValueSimplifyAA.getAssumedSimplifiedValue(A);
if (!SimplifiedVal.hasValue() ||
isa<UndefValue>(*SimplifiedVal.getValue())) {
KnownUBInsts.insert(&I);
continue;
}
if (!ArgVal->getType()->isPointerTy() ||
!isa<ConstantPointerNull>(*SimplifiedVal.getValue()))
continue;
auto &NonNullAA = A.getAAFor<AANonNull>(*this, CalleeArgumentIRP,
/* TrackDependence */ false);
if (NonNullAA.isKnownNonNull())
KnownUBInsts.insert(&I);
}
return true;
};
auto InspectReturnInstForUB =
[&](Value &V, const SmallSetVector<ReturnInst *, 4> RetInsts) {
// Check if a return instruction always cause UB or not
// Note: It is guaranteed that the returned position of the anchor
// scope has noundef attribute when this is called.
// We also ensure the return position is not "assumed dead"
// because the returned value was then potentially simplified to
// `undef` in AAReturnedValues without removing the `noundef`
// attribute yet.
// When the returned position has noundef attriubte, UB occur in the
// following cases.
// (1) Returned value is known to be undef.
// (2) The value is known to be a null pointer and the returned
// position has nonnull attribute (because the returned value is
// poison).
bool FoundUB = false;
if (isa<UndefValue>(V)) {
FoundUB = true;
} else {
if (isa<ConstantPointerNull>(V)) {
auto &NonNullAA = A.getAAFor<AANonNull>(
*this, IRPosition::returned(*getAnchorScope()),
/* TrackDependence */ false);
if (NonNullAA.isKnownNonNull())
FoundUB = true;
}
}
if (FoundUB)
for (ReturnInst *RI : RetInsts)
KnownUBInsts.insert(RI);
return true;
};
A.checkForAllInstructions(InspectMemAccessInstForUB, *this,
{Instruction::Load, Instruction::Store,
Instruction::AtomicCmpXchg,
Instruction::AtomicRMW},
/* CheckBBLivenessOnly */ true);
A.checkForAllInstructions(InspectBrInstForUB, *this, {Instruction::Br},
/* CheckBBLivenessOnly */ true);
A.checkForAllCallLikeInstructions(InspectCallSiteForUB, *this);
// If the returned position of the anchor scope has noundef attriubte, check
// all returned instructions.
if (!getAnchorScope()->getReturnType()->isVoidTy()) {
const IRPosition &ReturnIRP = IRPosition::returned(*getAnchorScope());
if (!A.isAssumedDead(ReturnIRP, this, nullptr)) {
auto &RetPosNoUndefAA =
A.getAAFor<AANoUndef>(*this, ReturnIRP,
/* TrackDependence */ false);
if (RetPosNoUndefAA.isKnownNoUndef())
A.checkForAllReturnedValuesAndReturnInsts(InspectReturnInstForUB,
*this);
}
}
if (NoUBPrevSize != AssumedNoUBInsts.size() ||
UBPrevSize != KnownUBInsts.size())
return ChangeStatus::CHANGED;
return ChangeStatus::UNCHANGED;
}
bool isKnownToCauseUB(Instruction *I) const override {
return KnownUBInsts.count(I);
}
bool isAssumedToCauseUB(Instruction *I) const override {
// In simple words, if an instruction is not in the assumed to _not_
// cause UB, then it is assumed UB (that includes those
// in the KnownUBInsts set). The rest is boilerplate
// is to ensure that it is one of the instructions we test
// for UB.
switch (I->getOpcode()) {
case Instruction::Load:
case Instruction::Store:
case Instruction::AtomicCmpXchg:
case Instruction::AtomicRMW:
return !AssumedNoUBInsts.count(I);
case Instruction::Br: {
auto BrInst = cast<BranchInst>(I);
if (BrInst->isUnconditional())
return false;
return !AssumedNoUBInsts.count(I);
} break;
default:
return false;
}
return false;
}
ChangeStatus manifest(Attributor &A) override {
if (KnownUBInsts.empty())
return ChangeStatus::UNCHANGED;
for (Instruction *I : KnownUBInsts)
A.changeToUnreachableAfterManifest(I);
return ChangeStatus::CHANGED;
}
/// See AbstractAttribute::getAsStr()
const std::string getAsStr() const override {
return getAssumed() ? "undefined-behavior" : "no-ub";
}
/// Note: The correctness of this analysis depends on the fact that the
/// following 2 sets will stop changing after some point.
/// "Change" here means that their size changes.
/// The size of each set is monotonically increasing
/// (we only add items to them) and it is upper bounded by the number of
/// instructions in the processed function (we can never save more
/// elements in either set than this number). Hence, at some point,
/// they will stop increasing.
/// Consequently, at some point, both sets will have stopped
/// changing, effectively making the analysis reach a fixpoint.
/// Note: These 2 sets are disjoint and an instruction can be considered
/// one of 3 things:
/// 1) Known to cause UB (AAUndefinedBehavior could prove it) and put it in
/// the KnownUBInsts set.
/// 2) Assumed to cause UB (in every updateImpl, AAUndefinedBehavior
/// has a reason to assume it).
/// 3) Assumed to not cause UB. very other instruction - AAUndefinedBehavior
/// could not find a reason to assume or prove that it can cause UB,
/// hence it assumes it doesn't. We have a set for these instructions
/// so that we don't reprocess them in every update.
/// Note however that instructions in this set may cause UB.
protected:
/// A set of all live instructions _known_ to cause UB.
SmallPtrSet<Instruction *, 8> KnownUBInsts;
private:
/// A set of all the (live) instructions that are assumed to _not_ cause UB.
SmallPtrSet<Instruction *, 8> AssumedNoUBInsts;
// Should be called on updates in which if we're processing an instruction
// \p I that depends on a value \p V, one of the following has to happen:
// - If the value is assumed, then stop.
// - If the value is known but undef, then consider it UB.
// - Otherwise, do specific processing with the simplified value.
// We return None in the first 2 cases to signify that an appropriate
// action was taken and the caller should stop.
// Otherwise, we return the simplified value that the caller should
// use for specific processing.
Optional<Value *> stopOnUndefOrAssumed(Attributor &A, const Value *V,
Instruction *I) {
const auto &ValueSimplifyAA =
A.getAAFor<AAValueSimplify>(*this, IRPosition::value(*V));
Optional<Value *> SimplifiedV =
ValueSimplifyAA.getAssumedSimplifiedValue(A);
if (!ValueSimplifyAA.isKnown()) {
// Don't depend on assumed values.
return llvm::None;
}
if (!SimplifiedV.hasValue()) {
// If it is known (which we tested above) but it doesn't have a value,
// then we can assume `undef` and hence the instruction is UB.
KnownUBInsts.insert(I);
return llvm::None;
}
Value *Val = SimplifiedV.getValue();
if (isa<UndefValue>(Val)) {
KnownUBInsts.insert(I);
return llvm::None;
}
return Val;
}
};
struct AAUndefinedBehaviorFunction final : AAUndefinedBehaviorImpl {
AAUndefinedBehaviorFunction(const IRPosition &IRP, Attributor &A)
: AAUndefinedBehaviorImpl(IRP, A) {}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
STATS_DECL(UndefinedBehaviorInstruction, Instruction,
"Number of instructions known to have UB");
BUILD_STAT_NAME(UndefinedBehaviorInstruction, Instruction) +=
KnownUBInsts.size();
}
};
/// ------------------------ Will-Return Attributes ----------------------------
// Helper function that checks whether a function has any cycle which we don't
// know if it is bounded or not.
// Loops with maximum trip count are considered bounded, any other cycle not.
static bool mayContainUnboundedCycle(Function &F, Attributor &A) {
ScalarEvolution *SE =
A.getInfoCache().getAnalysisResultForFunction<ScalarEvolutionAnalysis>(F);
LoopInfo *LI = A.getInfoCache().getAnalysisResultForFunction<LoopAnalysis>(F);
// If either SCEV or LoopInfo is not available for the function then we assume
// any cycle to be unbounded cycle.
// We use scc_iterator which uses Tarjan algorithm to find all the maximal
// SCCs.To detect if there's a cycle, we only need to find the maximal ones.
if (!SE || !LI) {
for (scc_iterator<Function *> SCCI = scc_begin(&F); !SCCI.isAtEnd(); ++SCCI)
if (SCCI.hasCycle())
return true;
return false;
}
// If there's irreducible control, the function may contain non-loop cycles.
if (mayContainIrreducibleControl(F, LI))
return true;
// Any loop that does not have a max trip count is considered unbounded cycle.
for (auto *L : LI->getLoopsInPreorder()) {
if (!SE->getSmallConstantMaxTripCount(L))
return true;
}
return false;
}
struct AAWillReturnImpl : public AAWillReturn {
AAWillReturnImpl(const IRPosition &IRP, Attributor &A)
: AAWillReturn(IRP, A) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
AAWillReturn::initialize(A);
Function *F = getAnchorScope();
if (!F || F->isDeclaration() || mayContainUnboundedCycle(*F, A))
indicatePessimisticFixpoint();
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
auto CheckForWillReturn = [&](Instruction &I) {
IRPosition IPos = IRPosition::callsite_function(cast<CallBase>(I));
const auto &WillReturnAA = A.getAAFor<AAWillReturn>(*this, IPos);
if (WillReturnAA.isKnownWillReturn())
return true;
if (!WillReturnAA.isAssumedWillReturn())
return false;
const auto &NoRecurseAA = A.getAAFor<AANoRecurse>(*this, IPos);
return NoRecurseAA.isAssumedNoRecurse();
};
if (!A.checkForAllCallLikeInstructions(CheckForWillReturn, *this))
return indicatePessimisticFixpoint();
return ChangeStatus::UNCHANGED;
}
/// See AbstractAttribute::getAsStr()
const std::string getAsStr() const override {
return getAssumed() ? "willreturn" : "may-noreturn";
}
};
struct AAWillReturnFunction final : AAWillReturnImpl {
AAWillReturnFunction(const IRPosition &IRP, Attributor &A)
: AAWillReturnImpl(IRP, A) {}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_FN_ATTR(willreturn) }
};
/// WillReturn attribute deduction for a call sites.
struct AAWillReturnCallSite final : AAWillReturnImpl {
AAWillReturnCallSite(const IRPosition &IRP, Attributor &A)
: AAWillReturnImpl(IRP, A) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
AAWillReturn::initialize(A);
Function *F = getAssociatedFunction();
if (!F || !A.isFunctionIPOAmendable(*F))
indicatePessimisticFixpoint();
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
// TODO: Once we have call site specific value information we can provide
// call site specific liveness information and then it makes
// sense to specialize attributes for call sites arguments instead of
// redirecting requests to the callee argument.
Function *F = getAssociatedFunction();
const IRPosition &FnPos = IRPosition::function(*F);
auto &FnAA = A.getAAFor<AAWillReturn>(*this, FnPos);
return clampStateAndIndicateChange(getState(), FnAA.getState());
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_CS_ATTR(willreturn); }
};
/// -------------------AAReachability Attribute--------------------------
struct AAReachabilityImpl : AAReachability {
AAReachabilityImpl(const IRPosition &IRP, Attributor &A)
: AAReachability(IRP, A) {}
const std::string getAsStr() const override {
// TODO: Return the number of reachable queries.
return "reachable";
}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override { indicatePessimisticFixpoint(); }
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
return indicatePessimisticFixpoint();
}
};
struct AAReachabilityFunction final : public AAReachabilityImpl {
AAReachabilityFunction(const IRPosition &IRP, Attributor &A)
: AAReachabilityImpl(IRP, A) {}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_FN_ATTR(reachable); }
};
/// ------------------------ NoAlias Argument Attribute ------------------------
struct AANoAliasImpl : AANoAlias {
AANoAliasImpl(const IRPosition &IRP, Attributor &A) : AANoAlias(IRP, A) {
assert(getAssociatedType()->isPointerTy() &&
"Noalias is a pointer attribute");
}
const std::string getAsStr() const override {
return getAssumed() ? "noalias" : "may-alias";
}
};
/// NoAlias attribute for a floating value.
struct AANoAliasFloating final : AANoAliasImpl {
AANoAliasFloating(const IRPosition &IRP, Attributor &A)
: AANoAliasImpl(IRP, A) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
AANoAliasImpl::initialize(A);
Value *Val = &getAssociatedValue();
do {
CastInst *CI = dyn_cast<CastInst>(Val);
if (!CI)
break;
Value *Base = CI->getOperand(0);
if (!Base->hasOneUse())
break;
Val = Base;
} while (true);
if (!Val->getType()->isPointerTy()) {
indicatePessimisticFixpoint();
return;
}
if (isa<AllocaInst>(Val))
indicateOptimisticFixpoint();
else if (isa<ConstantPointerNull>(Val) &&
!NullPointerIsDefined(getAnchorScope(),
Val->getType()->getPointerAddressSpace()))
indicateOptimisticFixpoint();
else if (Val != &getAssociatedValue()) {
const auto &ValNoAliasAA =
A.getAAFor<AANoAlias>(*this, IRPosition::value(*Val));
if (ValNoAliasAA.isKnownNoAlias())
indicateOptimisticFixpoint();
}
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
// TODO: Implement this.
return indicatePessimisticFixpoint();
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
STATS_DECLTRACK_FLOATING_ATTR(noalias)
}
};
/// NoAlias attribute for an argument.
struct AANoAliasArgument final
: AAArgumentFromCallSiteArguments<AANoAlias, AANoAliasImpl> {
using Base = AAArgumentFromCallSiteArguments<AANoAlias, AANoAliasImpl>;
AANoAliasArgument(const IRPosition &IRP, Attributor &A) : Base(IRP, A) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
Base::initialize(A);
// See callsite argument attribute and callee argument attribute.
if (hasAttr({Attribute::ByVal}))
indicateOptimisticFixpoint();
}
/// See AbstractAttribute::update(...).
ChangeStatus updateImpl(Attributor &A) override {
// We have to make sure no-alias on the argument does not break
// synchronization when this is a callback argument, see also [1] below.
// If synchronization cannot be affected, we delegate to the base updateImpl
// function, otherwise we give up for now.
// If the function is no-sync, no-alias cannot break synchronization.
const auto &NoSyncAA = A.getAAFor<AANoSync>(
*this, IRPosition::function_scope(getIRPosition()));
if (NoSyncAA.isAssumedNoSync())
return Base::updateImpl(A);
// If the argument is read-only, no-alias cannot break synchronization.
const auto &MemBehaviorAA =
A.getAAFor<AAMemoryBehavior>(*this, getIRPosition());
if (MemBehaviorAA.isAssumedReadOnly())
return Base::updateImpl(A);
// If the argument is never passed through callbacks, no-alias cannot break
// synchronization.
bool AllCallSitesKnown;
if (A.checkForAllCallSites(
[](AbstractCallSite ACS) { return !ACS.isCallbackCall(); }, *this,
true, AllCallSitesKnown))
return Base::updateImpl(A);
// TODO: add no-alias but make sure it doesn't break synchronization by
// introducing fake uses. See:
// [1] Compiler Optimizations for OpenMP, J. Doerfert and H. Finkel,
// International Workshop on OpenMP 2018,
// http://compilers.cs.uni-saarland.de/people/doerfert/par_opt18.pdf
return indicatePessimisticFixpoint();
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_ARG_ATTR(noalias) }
};
struct AANoAliasCallSiteArgument final : AANoAliasImpl {
AANoAliasCallSiteArgument(const IRPosition &IRP, Attributor &A)
: AANoAliasImpl(IRP, A) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
// See callsite argument attribute and callee argument attribute.
const auto &CB = cast<CallBase>(getAnchorValue());
if (CB.paramHasAttr(getCallSiteArgNo(), Attribute::NoAlias))
indicateOptimisticFixpoint();
Value &Val = getAssociatedValue();
if (isa<ConstantPointerNull>(Val) &&
!NullPointerIsDefined(getAnchorScope(),
Val.getType()->getPointerAddressSpace()))
indicateOptimisticFixpoint();
}
/// Determine if the underlying value may alias with the call site argument
/// \p OtherArgNo of \p ICS (= the underlying call site).
bool mayAliasWithArgument(Attributor &A, AAResults *&AAR,
const AAMemoryBehavior &MemBehaviorAA,
const CallBase &CB, unsigned OtherArgNo) {
// We do not need to worry about aliasing with the underlying IRP.
if (this->getCalleeArgNo() == (int)OtherArgNo)
return false;
// If it is not a pointer or pointer vector we do not alias.
const Value *ArgOp = CB.getArgOperand(OtherArgNo);
if (!ArgOp->getType()->isPtrOrPtrVectorTy())
return false;
auto &CBArgMemBehaviorAA = A.getAAFor<AAMemoryBehavior>(
*this, IRPosition::callsite_argument(CB, OtherArgNo),
/* TrackDependence */ false);
// If the argument is readnone, there is no read-write aliasing.
if (CBArgMemBehaviorAA.isAssumedReadNone()) {
A.recordDependence(CBArgMemBehaviorAA, *this, DepClassTy::OPTIONAL);
return false;
}
// If the argument is readonly and the underlying value is readonly, there
// is no read-write aliasing.
bool IsReadOnly = MemBehaviorAA.isAssumedReadOnly();
if (CBArgMemBehaviorAA.isAssumedReadOnly() && IsReadOnly) {
A.recordDependence(MemBehaviorAA, *this, DepClassTy::OPTIONAL);
A.recordDependence(CBArgMemBehaviorAA, *this, DepClassTy::OPTIONAL);
return false;
}
// We have to utilize actual alias analysis queries so we need the object.
if (!AAR)
AAR = A.getInfoCache().getAAResultsForFunction(*getAnchorScope());
// Try to rule it out at the call site.
bool IsAliasing = !AAR || !AAR->isNoAlias(&getAssociatedValue(), ArgOp);
LLVM_DEBUG(dbgs() << "[NoAliasCSArg] Check alias between "
"callsite arguments: "
<< getAssociatedValue() << " " << *ArgOp << " => "
<< (IsAliasing ? "" : "no-") << "alias \n");
return IsAliasing;
}
bool
isKnownNoAliasDueToNoAliasPreservation(Attributor &A, AAResults *&AAR,
const AAMemoryBehavior &MemBehaviorAA,
const AANoAlias &NoAliasAA) {
// We can deduce "noalias" if the following conditions hold.
// (i) Associated value is assumed to be noalias in the definition.
// (ii) Associated value is assumed to be no-capture in all the uses
// possibly executed before this callsite.
// (iii) There is no other pointer argument which could alias with the
// value.
bool AssociatedValueIsNoAliasAtDef = NoAliasAA.isAssumedNoAlias();
if (!AssociatedValueIsNoAliasAtDef) {
LLVM_DEBUG(dbgs() << "[AANoAlias] " << getAssociatedValue()
<< " is not no-alias at the definition\n");
return false;
}
A.recordDependence(NoAliasAA, *this, DepClassTy::OPTIONAL);
const IRPosition &VIRP = IRPosition::value(getAssociatedValue());
const Function *ScopeFn = VIRP.getAnchorScope();
auto &NoCaptureAA =
A.getAAFor<AANoCapture>(*this, VIRP, /* TrackDependence */ false);
// Check whether the value is captured in the scope using AANoCapture.
// Look at CFG and check only uses possibly executed before this
// callsite.
auto UsePred = [&](const Use &U, bool &Follow) -> bool {
Instruction *UserI = cast<Instruction>(U.getUser());
// If UserI is the curr instruction and there is a single potential use of
// the value in UserI we allow the use.
// TODO: We should inspect the operands and allow those that cannot alias
// with the value.
if (UserI == getCtxI() && UserI->getNumOperands() == 1)
return true;
if (ScopeFn) {
const auto &ReachabilityAA =
A.getAAFor<AAReachability>(*this, IRPosition::function(*ScopeFn));
if (!ReachabilityAA.isAssumedReachable(A, *UserI, *getCtxI()))
return true;
if (auto *CB = dyn_cast<CallBase>(UserI)) {
if (CB->isArgOperand(&U)) {
unsigned ArgNo = CB->getArgOperandNo(&U);
const auto &NoCaptureAA = A.getAAFor<AANoCapture>(
*this, IRPosition::callsite_argument(*CB, ArgNo));
if (NoCaptureAA.isAssumedNoCapture())
return true;
}
}
}
// For cases which can potentially have more users
if (isa<GetElementPtrInst>(U) || isa<BitCastInst>(U) || isa<PHINode>(U) ||
isa<SelectInst>(U)) {
Follow = true;
return true;
}
LLVM_DEBUG(dbgs() << "[AANoAliasCSArg] Unknown user: " << *U << "\n");
return false;
};
if (!NoCaptureAA.isAssumedNoCaptureMaybeReturned()) {
if (!A.checkForAllUses(UsePred, *this, getAssociatedValue())) {
LLVM_DEBUG(
dbgs() << "[AANoAliasCSArg] " << getAssociatedValue()
<< " cannot be noalias as it is potentially captured\n");
return false;
}
}
A.recordDependence(NoCaptureAA, *this, DepClassTy::OPTIONAL);
// Check there is no other pointer argument which could alias with the
// value passed at this call site.
// TODO: AbstractCallSite
const auto &CB = cast<CallBase>(getAnchorValue());
for (unsigned OtherArgNo = 0; OtherArgNo < CB.getNumArgOperands();
OtherArgNo++)
if (mayAliasWithArgument(A, AAR, MemBehaviorAA, CB, OtherArgNo))
return false;
return true;
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
// If the argument is readnone we are done as there are no accesses via the
// argument.
auto &MemBehaviorAA =
A.getAAFor<AAMemoryBehavior>(*this, getIRPosition(),
/* TrackDependence */ false);
if (MemBehaviorAA.isAssumedReadNone()) {
A.recordDependence(MemBehaviorAA, *this, DepClassTy::OPTIONAL);
return ChangeStatus::UNCHANGED;
}
const IRPosition &VIRP = IRPosition::value(getAssociatedValue());
const auto &NoAliasAA = A.getAAFor<AANoAlias>(*this, VIRP,
/* TrackDependence */ false);
AAResults *AAR = nullptr;
if (isKnownNoAliasDueToNoAliasPreservation(A, AAR, MemBehaviorAA,
NoAliasAA)) {
LLVM_DEBUG(
dbgs() << "[AANoAlias] No-Alias deduced via no-alias preservation\n");
return ChangeStatus::UNCHANGED;
}
return indicatePessimisticFixpoint();
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_CSARG_ATTR(noalias) }
};
/// NoAlias attribute for function return value.
struct AANoAliasReturned final : AANoAliasImpl {
AANoAliasReturned(const IRPosition &IRP, Attributor &A)
: AANoAliasImpl(IRP, A) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
AANoAliasImpl::initialize(A);
Function *F = getAssociatedFunction();
if (!F || F->isDeclaration())
indicatePessimisticFixpoint();
}
/// See AbstractAttribute::updateImpl(...).
virtual ChangeStatus updateImpl(Attributor &A) override {
auto CheckReturnValue = [&](Value &RV) -> bool {
if (Constant *C = dyn_cast<Constant>(&RV))
if (C->isNullValue() || isa<UndefValue>(C))
return true;
/// For now, we can only deduce noalias if we have call sites.
/// FIXME: add more support.
if (!isa<CallBase>(&RV))
return false;
const IRPosition &RVPos = IRPosition::value(RV);
const auto &NoAliasAA = A.getAAFor<AANoAlias>(*this, RVPos);
if (!NoAliasAA.isAssumedNoAlias())
return false;
const auto &NoCaptureAA = A.getAAFor<AANoCapture>(*this, RVPos);
return NoCaptureAA.isAssumedNoCaptureMaybeReturned();
};
if (!A.checkForAllReturnedValues(CheckReturnValue, *this))
return indicatePessimisticFixpoint();
return ChangeStatus::UNCHANGED;
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_FNRET_ATTR(noalias) }
};
/// NoAlias attribute deduction for a call site return value.
struct AANoAliasCallSiteReturned final : AANoAliasImpl {
AANoAliasCallSiteReturned(const IRPosition &IRP, Attributor &A)
: AANoAliasImpl(IRP, A) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
AANoAliasImpl::initialize(A);
Function *F = getAssociatedFunction();
if (!F || F->isDeclaration())
indicatePessimisticFixpoint();
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
// TODO: Once we have call site specific value information we can provide
// call site specific liveness information and then it makes
// sense to specialize attributes for call sites arguments instead of
// redirecting requests to the callee argument.
Function *F = getAssociatedFunction();
const IRPosition &FnPos = IRPosition::returned(*F);
auto &FnAA = A.getAAFor<AANoAlias>(*this, FnPos);
return clampStateAndIndicateChange(getState(), FnAA.getState());
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_CSRET_ATTR(noalias); }
};
/// -------------------AAIsDead Function Attribute-----------------------
struct AAIsDeadValueImpl : public AAIsDead {
AAIsDeadValueImpl(const IRPosition &IRP, Attributor &A) : AAIsDead(IRP, A) {}
/// See AAIsDead::isAssumedDead().
bool isAssumedDead() const override { return getAssumed(); }
/// See AAIsDead::isKnownDead().
bool isKnownDead() const override { return getKnown(); }
/// See AAIsDead::isAssumedDead(BasicBlock *).
bool isAssumedDead(const BasicBlock *BB) const override { return false; }
/// See AAIsDead::isKnownDead(BasicBlock *).
bool isKnownDead(const BasicBlock *BB) const override { return false; }
/// See AAIsDead::isAssumedDead(Instruction *I).
bool isAssumedDead(const Instruction *I) const override {
return I == getCtxI() && isAssumedDead();
}
/// See AAIsDead::isKnownDead(Instruction *I).
bool isKnownDead(const Instruction *I) const override {
return isAssumedDead(I) && getKnown();
}
/// See AbstractAttribute::getAsStr().
const std::string getAsStr() const override {
return isAssumedDead() ? "assumed-dead" : "assumed-live";
}
/// Check if all uses are assumed dead.
bool areAllUsesAssumedDead(Attributor &A, Value &V) {
auto UsePred = [&](const Use &U, bool &Follow) { return false; };
// Explicitly set the dependence class to required because we want a long
// chain of N dependent instructions to be considered live as soon as one is
// without going through N update cycles. This is not required for
// correctness.
return A.checkForAllUses(UsePred, *this, V, DepClassTy::REQUIRED);
}
/// Determine if \p I is assumed to be side-effect free.
bool isAssumedSideEffectFree(Attributor &A, Instruction *I) {
if (!I || wouldInstructionBeTriviallyDead(I))
return true;
auto *CB = dyn_cast<CallBase>(I);
if (!CB || isa<IntrinsicInst>(CB))
return false;
const IRPosition &CallIRP = IRPosition::callsite_function(*CB);
const auto &NoUnwindAA = A.getAndUpdateAAFor<AANoUnwind>(
*this, CallIRP, /* TrackDependence */ false);
if (!NoUnwindAA.isAssumedNoUnwind())
return false;
if (!NoUnwindAA.isKnownNoUnwind())
A.recordDependence(NoUnwindAA, *this, DepClassTy::OPTIONAL);
const auto &MemBehaviorAA = A.getAndUpdateAAFor<AAMemoryBehavior>(
*this, CallIRP, /* TrackDependence */ false);
if (MemBehaviorAA.isAssumedReadOnly()) {
if (!MemBehaviorAA.isKnownReadOnly())
A.recordDependence(MemBehaviorAA, *this, DepClassTy::OPTIONAL);
return true;
}
return false;
}
};
struct AAIsDeadFloating : public AAIsDeadValueImpl {
AAIsDeadFloating(const IRPosition &IRP, Attributor &A)
: AAIsDeadValueImpl(IRP, A) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
if (isa<UndefValue>(getAssociatedValue())) {
indicatePessimisticFixpoint();
return;
}
Instruction *I = dyn_cast<Instruction>(&getAssociatedValue());
if (!isAssumedSideEffectFree(A, I))
indicatePessimisticFixpoint();
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
Instruction *I = dyn_cast<Instruction>(&getAssociatedValue());
if (!isAssumedSideEffectFree(A, I))
return indicatePessimisticFixpoint();
if (!areAllUsesAssumedDead(A, getAssociatedValue()))
return indicatePessimisticFixpoint();
return ChangeStatus::UNCHANGED;
}
/// See AbstractAttribute::manifest(...).
ChangeStatus manifest(Attributor &A) override {
Value &V = getAssociatedValue();
if (auto *I = dyn_cast<Instruction>(&V)) {
// If we get here we basically know the users are all dead. We check if
// isAssumedSideEffectFree returns true here again because it might not be
// the case and only the users are dead but the instruction (=call) is
// still needed.
if (isAssumedSideEffectFree(A, I) && !isa<InvokeInst>(I)) {
A.deleteAfterManifest(*I);
return ChangeStatus::CHANGED;
}
}
if (V.use_empty())
return ChangeStatus::UNCHANGED;
bool UsedAssumedInformation = false;
Optional<Constant *> C =
A.getAssumedConstant(V, *this, UsedAssumedInformation);
if (C.hasValue() && C.getValue())
return ChangeStatus::UNCHANGED;
// Replace the value with undef as it is dead but keep droppable uses around
// as they provide information we don't want to give up on just yet.
UndefValue &UV = *UndefValue::get(V.getType());
bool AnyChange =
A.changeValueAfterManifest(V, UV, /* ChangeDropppable */ false);
return AnyChange ? ChangeStatus::CHANGED : ChangeStatus::UNCHANGED;
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
STATS_DECLTRACK_FLOATING_ATTR(IsDead)
}
};
struct AAIsDeadArgument : public AAIsDeadFloating {
AAIsDeadArgument(const IRPosition &IRP, Attributor &A)
: AAIsDeadFloating(IRP, A) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
if (!A.isFunctionIPOAmendable(*getAnchorScope()))
indicatePessimisticFixpoint();
}
/// See AbstractAttribute::manifest(...).
ChangeStatus manifest(Attributor &A) override {
ChangeStatus Changed = AAIsDeadFloating::manifest(A);
Argument &Arg = *getAssociatedArgument();
if (A.isValidFunctionSignatureRewrite(Arg, /* ReplacementTypes */ {}))
if (A.registerFunctionSignatureRewrite(
Arg, /* ReplacementTypes */ {},
Attributor::ArgumentReplacementInfo::CalleeRepairCBTy{},
Attributor::ArgumentReplacementInfo::ACSRepairCBTy{})) {
Arg.dropDroppableUses();
return ChangeStatus::CHANGED;
}
return Changed;
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_ARG_ATTR(IsDead) }
};
struct AAIsDeadCallSiteArgument : public AAIsDeadValueImpl {
AAIsDeadCallSiteArgument(const IRPosition &IRP, Attributor &A)
: AAIsDeadValueImpl(IRP, A) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
if (isa<UndefValue>(getAssociatedValue()))
indicatePessimisticFixpoint();
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
// TODO: Once we have call site specific value information we can provide
// call site specific liveness information and then it makes
// sense to specialize attributes for call sites arguments instead of
// redirecting requests to the callee argument.
Argument *Arg = getAssociatedArgument();
if (!Arg)
return indicatePessimisticFixpoint();
const IRPosition &ArgPos = IRPosition::argument(*Arg);
auto &ArgAA = A.getAAFor<AAIsDead>(*this, ArgPos);
return clampStateAndIndicateChange(getState(), ArgAA.getState());
}
/// See AbstractAttribute::manifest(...).
ChangeStatus manifest(Attributor &A) override {
CallBase &CB = cast<CallBase>(getAnchorValue());
Use &U = CB.getArgOperandUse(getCallSiteArgNo());
assert(!isa<UndefValue>(U.get()) &&
"Expected undef values to be filtered out!");
UndefValue &UV = *UndefValue::get(U->getType());
if (A.changeUseAfterManifest(U, UV))
return ChangeStatus::CHANGED;
return ChangeStatus::UNCHANGED;
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_CSARG_ATTR(IsDead) }
};
struct AAIsDeadCallSiteReturned : public AAIsDeadFloating {
AAIsDeadCallSiteReturned(const IRPosition &IRP, Attributor &A)
: AAIsDeadFloating(IRP, A), IsAssumedSideEffectFree(true) {}
/// See AAIsDead::isAssumedDead().
bool isAssumedDead() const override {
return AAIsDeadFloating::isAssumedDead() && IsAssumedSideEffectFree;
}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
if (isa<UndefValue>(getAssociatedValue())) {
indicatePessimisticFixpoint();
return;
}
// We track this separately as a secondary state.
IsAssumedSideEffectFree = isAssumedSideEffectFree(A, getCtxI());
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
ChangeStatus Changed = ChangeStatus::UNCHANGED;
if (IsAssumedSideEffectFree && !isAssumedSideEffectFree(A, getCtxI())) {
IsAssumedSideEffectFree = false;
Changed = ChangeStatus::CHANGED;
}
if (!areAllUsesAssumedDead(A, getAssociatedValue()))
return indicatePessimisticFixpoint();
return Changed;
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
if (IsAssumedSideEffectFree)
STATS_DECLTRACK_CSRET_ATTR(IsDead)
else
STATS_DECLTRACK_CSRET_ATTR(UnusedResult)
}
/// See AbstractAttribute::getAsStr().
const std::string getAsStr() const override {
return isAssumedDead()
? "assumed-dead"
: (getAssumed() ? "assumed-dead-users" : "assumed-live");
}
private:
bool IsAssumedSideEffectFree;
};
struct AAIsDeadReturned : public AAIsDeadValueImpl {
AAIsDeadReturned(const IRPosition &IRP, Attributor &A)
: AAIsDeadValueImpl(IRP, A) {}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
A.checkForAllInstructions([](Instruction &) { return true; }, *this,
{Instruction::Ret});
auto PredForCallSite = [&](AbstractCallSite ACS) {
if (ACS.isCallbackCall() || !ACS.getInstruction())
return false;
return areAllUsesAssumedDead(A, *ACS.getInstruction());
};
bool AllCallSitesKnown;
if (!A.checkForAllCallSites(PredForCallSite, *this, true,
AllCallSitesKnown))
return indicatePessimisticFixpoint();
return ChangeStatus::UNCHANGED;
}
/// See AbstractAttribute::manifest(...).
ChangeStatus manifest(Attributor &A) override {
// TODO: Rewrite the signature to return void?
bool AnyChange = false;
UndefValue &UV = *UndefValue::get(getAssociatedFunction()->getReturnType());
auto RetInstPred = [&](Instruction &I) {
ReturnInst &RI = cast<ReturnInst>(I);
if (!isa<UndefValue>(RI.getReturnValue()))
AnyChange |= A.changeUseAfterManifest(RI.getOperandUse(0), UV);
return true;
};
A.checkForAllInstructions(RetInstPred, *this, {Instruction::Ret});
return AnyChange ? ChangeStatus::CHANGED : ChangeStatus::UNCHANGED;
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_FNRET_ATTR(IsDead) }
};
struct AAIsDeadFunction : public AAIsDead {
AAIsDeadFunction(const IRPosition &IRP, Attributor &A) : AAIsDead(IRP, A) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
const Function *F = getAnchorScope();
if (F && !F->isDeclaration()) {
// We only want to compute liveness once. If the function is not part of
// the SCC, skip it.
if (A.isRunOn(*const_cast<Function *>(F))) {
ToBeExploredFrom.insert(&F->getEntryBlock().front());
assumeLive(A, F->getEntryBlock());
} else {
indicatePessimisticFixpoint();
}
}
}
/// See AbstractAttribute::getAsStr().
const std::string getAsStr() const override {
return "Live[#BB " + std::to_string(AssumedLiveBlocks.size()) + "/" +
std::to_string(getAnchorScope()->size()) + "][#TBEP " +
std::to_string(ToBeExploredFrom.size()) + "][#KDE " +
std::to_string(KnownDeadEnds.size()) + "]";
}
/// See AbstractAttribute::manifest(...).
ChangeStatus manifest(Attributor &A) override {
assert(getState().isValidState() &&
"Attempted to manifest an invalid state!");
ChangeStatus HasChanged = ChangeStatus::UNCHANGED;
Function &F = *getAnchorScope();
if (AssumedLiveBlocks.empty()) {
A.deleteAfterManifest(F);
return ChangeStatus::CHANGED;
}
// Flag to determine if we can change an invoke to a call assuming the
// callee is nounwind. This is not possible if the personality of the
// function allows to catch asynchronous exceptions.
bool Invoke2CallAllowed = !mayCatchAsynchronousExceptions(F);
KnownDeadEnds.set_union(ToBeExploredFrom);
for (const Instruction *DeadEndI : KnownDeadEnds) {
auto *CB = dyn_cast<CallBase>(DeadEndI);
if (!CB)
continue;
const auto &NoReturnAA = A.getAndUpdateAAFor<AANoReturn>(
*this, IRPosition::callsite_function(*CB), /* TrackDependence */ true,
DepClassTy::OPTIONAL);
bool MayReturn = !NoReturnAA.isAssumedNoReturn();
if (MayReturn && (!Invoke2CallAllowed || !isa<InvokeInst>(CB)))
continue;
if (auto *II = dyn_cast<InvokeInst>(DeadEndI))
A.registerInvokeWithDeadSuccessor(const_cast<InvokeInst &>(*II));
else
A.changeToUnreachableAfterManifest(
const_cast<Instruction *>(DeadEndI->getNextNode()));
HasChanged = ChangeStatus::CHANGED;
}
STATS_DECL(AAIsDead, BasicBlock, "Number of dead basic blocks deleted.");
for (BasicBlock &BB : F)
if (!AssumedLiveBlocks.count(&BB)) {
A.deleteAfterManifest(BB);
++BUILD_STAT_NAME(AAIsDead, BasicBlock);
}
return HasChanged;
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override;
bool isEdgeDead(const BasicBlock *From, const BasicBlock *To) const override {
return !AssumedLiveEdges.count(std::make_pair(From, To));
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {}
/// Returns true if the function is assumed dead.
bool isAssumedDead() const override { return false; }
/// See AAIsDead::isKnownDead().
bool isKnownDead() const override { return false; }
/// See AAIsDead::isAssumedDead(BasicBlock *).
bool isAssumedDead(const BasicBlock *BB) const override {
assert(BB->getParent() == getAnchorScope() &&
"BB must be in the same anchor scope function.");
if (!getAssumed())
return false;
return !AssumedLiveBlocks.count(BB);
}
/// See AAIsDead::isKnownDead(BasicBlock *).
bool isKnownDead(const BasicBlock *BB) const override {
return getKnown() && isAssumedDead(BB);
}
/// See AAIsDead::isAssumed(Instruction *I).
bool isAssumedDead(const Instruction *I) const override {
assert(I->getParent()->getParent() == getAnchorScope() &&
"Instruction must be in the same anchor scope function.");
if (!getAssumed())
return false;
// If it is not in AssumedLiveBlocks then it for sure dead.
// Otherwise, it can still be after noreturn call in a live block.
if (!AssumedLiveBlocks.count(I->getParent()))
return true;
// If it is not after a liveness barrier it is live.
const Instruction *PrevI = I->getPrevNode();
while (PrevI) {
if (KnownDeadEnds.count(PrevI) || ToBeExploredFrom.count(PrevI))
return true;
PrevI = PrevI->getPrevNode();
}
return false;
}
/// See AAIsDead::isKnownDead(Instruction *I).
bool isKnownDead(const Instruction *I) const override {
return getKnown() && isAssumedDead(I);
}
/// Assume \p BB is (partially) live now and indicate to the Attributor \p A
/// that internal function called from \p BB should now be looked at.
bool assumeLive(Attributor &A, const BasicBlock &BB) {
if (!AssumedLiveBlocks.insert(&BB).second)
return false;
// We assume that all of BB is (probably) live now and if there are calls to
// internal functions we will assume that those are now live as well. This
// is a performance optimization for blocks with calls to a lot of internal
// functions. It can however cause dead functions to be treated as live.
for (const Instruction &I : BB)
if (const auto *CB = dyn_cast<CallBase>(&I))
if (const Function *F = CB->getCalledFunction())
if (F->hasLocalLinkage())
A.markLiveInternalFunction(*F);
return true;
}
/// Collection of instructions that need to be explored again, e.g., we
/// did assume they do not transfer control to (one of their) successors.
SmallSetVector<const Instruction *, 8> ToBeExploredFrom;
/// Collection of instructions that are known to not transfer control.
SmallSetVector<const Instruction *, 8> KnownDeadEnds;
/// Collection of all assumed live edges
DenseSet<std::pair<const BasicBlock *, const BasicBlock *>> AssumedLiveEdges;
/// Collection of all assumed live BasicBlocks.
DenseSet<const BasicBlock *> AssumedLiveBlocks;
};
static bool
identifyAliveSuccessors(Attributor &A, const CallBase &CB,
AbstractAttribute &AA,
SmallVectorImpl<const Instruction *> &AliveSuccessors) {
const IRPosition &IPos = IRPosition::callsite_function(CB);
const auto &NoReturnAA = A.getAndUpdateAAFor<AANoReturn>(
AA, IPos, /* TrackDependence */ true, DepClassTy::OPTIONAL);
if (NoReturnAA.isAssumedNoReturn())
return !NoReturnAA.isKnownNoReturn();
if (CB.isTerminator())
AliveSuccessors.push_back(&CB.getSuccessor(0)->front());
else
AliveSuccessors.push_back(CB.getNextNode());
return false;
}
static bool
identifyAliveSuccessors(Attributor &A, const InvokeInst &II,
AbstractAttribute &AA,
SmallVectorImpl<const Instruction *> &AliveSuccessors) {
bool UsedAssumedInformation =
identifyAliveSuccessors(A, cast<CallBase>(II), AA, AliveSuccessors);
// First, determine if we can change an invoke to a call assuming the
// callee is nounwind. This is not possible if the personality of the
// function allows to catch asynchronous exceptions.
if (AAIsDeadFunction::mayCatchAsynchronousExceptions(*II.getFunction())) {
AliveSuccessors.push_back(&II.getUnwindDest()->front());
} else {
const IRPosition &IPos = IRPosition::callsite_function(II);
const auto &AANoUnw = A.getAndUpdateAAFor<AANoUnwind>(
AA, IPos, /* TrackDependence */ true, DepClassTy::OPTIONAL);
if (AANoUnw.isAssumedNoUnwind()) {
UsedAssumedInformation |= !AANoUnw.isKnownNoUnwind();
} else {
AliveSuccessors.push_back(&II.getUnwindDest()->front());
}
}
return UsedAssumedInformation;
}
static bool
identifyAliveSuccessors(Attributor &A, const BranchInst &BI,
AbstractAttribute &AA,
SmallVectorImpl<const Instruction *> &AliveSuccessors) {
bool UsedAssumedInformation = false;
if (BI.getNumSuccessors() == 1) {
AliveSuccessors.push_back(&BI.getSuccessor(0)->front());
} else {
Optional<ConstantInt *> CI = getAssumedConstantInt(
A, *BI.getCondition(), AA, UsedAssumedInformation);
if (!CI.hasValue()) {
// No value yet, assume both edges are dead.
} else if (CI.getValue()) {
const BasicBlock *SuccBB =
BI.getSuccessor(1 - CI.getValue()->getZExtValue());
AliveSuccessors.push_back(&SuccBB->front());
} else {
AliveSuccessors.push_back(&BI.getSuccessor(0)->front());
AliveSuccessors.push_back(&BI.getSuccessor(1)->front());
UsedAssumedInformation = false;
}
}
return UsedAssumedInformation;
}
static bool
identifyAliveSuccessors(Attributor &A, const SwitchInst &SI,
AbstractAttribute &AA,
SmallVectorImpl<const Instruction *> &AliveSuccessors) {
bool UsedAssumedInformation = false;
Optional<ConstantInt *> CI =
getAssumedConstantInt(A, *SI.getCondition(), AA, UsedAssumedInformation);
if (!CI.hasValue()) {
// No value yet, assume all edges are dead.
} else if (CI.getValue()) {
for (auto &CaseIt : SI.cases()) {
if (CaseIt.getCaseValue() == CI.getValue()) {
AliveSuccessors.push_back(&CaseIt.getCaseSuccessor()->front());
return UsedAssumedInformation;
}
}
AliveSuccessors.push_back(&SI.getDefaultDest()->front());
return UsedAssumedInformation;
} else {
for (const BasicBlock *SuccBB : successors(SI.getParent()))
AliveSuccessors.push_back(&SuccBB->front());
}
return UsedAssumedInformation;
}
ChangeStatus AAIsDeadFunction::updateImpl(Attributor &A) {
ChangeStatus Change = ChangeStatus::UNCHANGED;
LLVM_DEBUG(dbgs() << "[AAIsDead] Live [" << AssumedLiveBlocks.size() << "/"
<< getAnchorScope()->size() << "] BBs and "
<< ToBeExploredFrom.size() << " exploration points and "
<< KnownDeadEnds.size() << " known dead ends\n");
// Copy and clear the list of instructions we need to explore from. It is
// refilled with instructions the next update has to look at.
SmallVector<const Instruction *, 8> Worklist(ToBeExploredFrom.begin(),
ToBeExploredFrom.end());
decltype(ToBeExploredFrom) NewToBeExploredFrom;
SmallVector<const Instruction *, 8> AliveSuccessors;
while (!Worklist.empty()) {
const Instruction *I = Worklist.pop_back_val();
LLVM_DEBUG(dbgs() << "[AAIsDead] Exploration inst: " << *I << "\n");
// Fast forward for uninteresting instructions. We could look for UB here
// though.
while (!I->isTerminator() && !isa<CallBase>(I)) {
Change = ChangeStatus::CHANGED;
I = I->getNextNode();
}
AliveSuccessors.clear();
bool UsedAssumedInformation = false;
switch (I->getOpcode()) {
// TODO: look for (assumed) UB to backwards propagate "deadness".
default:
assert(I->isTerminator() &&
"Expected non-terminators to be handled already!");
for (const BasicBlock *SuccBB : successors(I->getParent()))
AliveSuccessors.push_back(&SuccBB->front());
break;
case Instruction::Call:
UsedAssumedInformation = identifyAliveSuccessors(A, cast<CallInst>(*I),
*this, AliveSuccessors);
break;
case Instruction::Invoke:
UsedAssumedInformation = identifyAliveSuccessors(A, cast<InvokeInst>(*I),
*this, AliveSuccessors);
break;
case Instruction::Br:
UsedAssumedInformation = identifyAliveSuccessors(A, cast<BranchInst>(*I),
*this, AliveSuccessors);
break;
case Instruction::Switch:
UsedAssumedInformation = identifyAliveSuccessors(A, cast<SwitchInst>(*I),
*this, AliveSuccessors);
break;
}
if (UsedAssumedInformation) {
NewToBeExploredFrom.insert(I);
} else {
Change = ChangeStatus::CHANGED;
if (AliveSuccessors.empty() ||
(I->isTerminator() && AliveSuccessors.size() < I->getNumSuccessors()))
KnownDeadEnds.insert(I);
}
LLVM_DEBUG(dbgs() << "[AAIsDead] #AliveSuccessors: "
<< AliveSuccessors.size() << " UsedAssumedInformation: "
<< UsedAssumedInformation << "\n");
for (const Instruction *AliveSuccessor : AliveSuccessors) {
if (!I->isTerminator()) {
assert(AliveSuccessors.size() == 1 &&
"Non-terminator expected to have a single successor!");
Worklist.push_back(AliveSuccessor);
} else {
// record the assumed live edge
AssumedLiveEdges.insert(
std::make_pair(I->getParent(), AliveSuccessor->getParent()));
if (assumeLive(A, *AliveSuccessor->getParent()))
Worklist.push_back(AliveSuccessor);
}
}
}
ToBeExploredFrom = std::move(NewToBeExploredFrom);
// If we know everything is live there is no need to query for liveness.
// Instead, indicating a pessimistic fixpoint will cause the state to be
// "invalid" and all queries to be answered conservatively without lookups.
// To be in this state we have to (1) finished the exploration and (3) not
// discovered any non-trivial dead end and (2) not ruled unreachable code
// dead.
if (ToBeExploredFrom.empty() &&
getAnchorScope()->size() == AssumedLiveBlocks.size() &&
llvm::all_of(KnownDeadEnds, [](const Instruction *DeadEndI) {
return DeadEndI->isTerminator() && DeadEndI->getNumSuccessors() == 0;
}))
return indicatePessimisticFixpoint();
return Change;
}
/// Liveness information for a call sites.
struct AAIsDeadCallSite final : AAIsDeadFunction {
AAIsDeadCallSite(const IRPosition &IRP, Attributor &A)
: AAIsDeadFunction(IRP, A) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
// TODO: Once we have call site specific value information we can provide
// call site specific liveness information and then it makes
// sense to specialize attributes for call sites instead of
// redirecting requests to the callee.
llvm_unreachable("Abstract attributes for liveness are not "
"supported for call sites yet!");
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
return indicatePessimisticFixpoint();
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {}
};
/// -------------------- Dereferenceable Argument Attribute --------------------
template <>
ChangeStatus clampStateAndIndicateChange<DerefState>(DerefState &S,
const DerefState &R) {
ChangeStatus CS0 =
clampStateAndIndicateChange(S.DerefBytesState, R.DerefBytesState);
ChangeStatus CS1 = clampStateAndIndicateChange(S.GlobalState, R.GlobalState);
return CS0 | CS1;
}
struct AADereferenceableImpl : AADereferenceable {
AADereferenceableImpl(const IRPosition &IRP, Attributor &A)
: AADereferenceable(IRP, A) {}
using StateType = DerefState;
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
SmallVector<Attribute, 4> Attrs;
getAttrs({Attribute::Dereferenceable, Attribute::DereferenceableOrNull},
Attrs, /* IgnoreSubsumingPositions */ false, &A);
for (const Attribute &Attr : Attrs)
takeKnownDerefBytesMaximum(Attr.getValueAsInt());
const IRPosition &IRP = this->getIRPosition();
NonNullAA = &A.getAAFor<AANonNull>(*this, IRP,
/* TrackDependence */ false);
bool CanBeNull;
takeKnownDerefBytesMaximum(
IRP.getAssociatedValue().getPointerDereferenceableBytes(
A.getDataLayout(), CanBeNull));
bool IsFnInterface = IRP.isFnInterfaceKind();
Function *FnScope = IRP.getAnchorScope();
if (IsFnInterface && (!FnScope || !A.isFunctionIPOAmendable(*FnScope))) {
indicatePessimisticFixpoint();
return;
}
if (Instruction *CtxI = getCtxI())
followUsesInMBEC(*this, A, getState(), *CtxI);
}
/// See AbstractAttribute::getState()
/// {
StateType &getState() override { return *this; }
const StateType &getState() const override { return *this; }
/// }
/// Helper function for collecting accessed bytes in must-be-executed-context
void addAccessedBytesForUse(Attributor &A, const Use *U, const Instruction *I,
DerefState &State) {
const Value *UseV = U->get();
if (!UseV->getType()->isPointerTy())
return;
Type *PtrTy = UseV->getType();
const DataLayout &DL = A.getDataLayout();
int64_t Offset;
if (const Value *Base = getBasePointerOfAccessPointerOperand(
I, Offset, DL, /*AllowNonInbounds*/ true)) {
if (Base == &getAssociatedValue() &&
getPointerOperand(I, /* AllowVolatile */ false) == UseV) {
uint64_t Size = DL.getTypeStoreSize(PtrTy->getPointerElementType());
State.addAccessedBytes(Offset, Size);
}
}
}
/// See followUsesInMBEC
bool followUseInMBEC(Attributor &A, const Use *U, const Instruction *I,
AADereferenceable::StateType &State) {
bool IsNonNull = false;
bool TrackUse = false;
int64_t DerefBytes = getKnownNonNullAndDerefBytesForUse(
A, *this, getAssociatedValue(), U, I, IsNonNull, TrackUse);
LLVM_DEBUG(dbgs() << "[AADereferenceable] Deref bytes: " << DerefBytes
<< " for instruction " << *I << "\n");
addAccessedBytesForUse(A, U, I, State);
State.takeKnownDerefBytesMaximum(DerefBytes);
return TrackUse;
}
/// See AbstractAttribute::manifest(...).
ChangeStatus manifest(Attributor &A) override {
ChangeStatus Change = AADereferenceable::manifest(A);
if (isAssumedNonNull() && hasAttr(Attribute::DereferenceableOrNull)) {
removeAttrs({Attribute::DereferenceableOrNull});
return ChangeStatus::CHANGED;
}
return Change;
}
void getDeducedAttributes(LLVMContext &Ctx,
SmallVectorImpl<Attribute> &Attrs) const override {
// TODO: Add *_globally support
if (isAssumedNonNull())
Attrs.emplace_back(Attribute::getWithDereferenceableBytes(
Ctx, getAssumedDereferenceableBytes()));
else
Attrs.emplace_back(Attribute::getWithDereferenceableOrNullBytes(
Ctx, getAssumedDereferenceableBytes()));
}
/// See AbstractAttribute::getAsStr().
const std::string getAsStr() const override {
if (!getAssumedDereferenceableBytes())
return "unknown-dereferenceable";
return std::string("dereferenceable") +
(isAssumedNonNull() ? "" : "_or_null") +
(isAssumedGlobal() ? "_globally" : "") + "<" +
std::to_string(getKnownDereferenceableBytes()) + "-" +
std::to_string(getAssumedDereferenceableBytes()) + ">";
}
};
/// Dereferenceable attribute for a floating value.
struct AADereferenceableFloating : AADereferenceableImpl {
AADereferenceableFloating(const IRPosition &IRP, Attributor &A)
: AADereferenceableImpl(IRP, A) {}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
const DataLayout &DL = A.getDataLayout();
auto VisitValueCB = [&](const Value &V, const Instruction *, DerefState &T,
bool Stripped) -> bool {
unsigned IdxWidth =
DL.getIndexSizeInBits(V.getType()->getPointerAddressSpace());
APInt Offset(IdxWidth, 0);
const Value *Base =
stripAndAccumulateMinimalOffsets(A, *this, &V, DL, Offset, false);
const auto &AA =
A.getAAFor<AADereferenceable>(*this, IRPosition::value(*Base));
int64_t DerefBytes = 0;
if (!Stripped && this == &AA) {
// Use IR information if we did not strip anything.
// TODO: track globally.
bool CanBeNull;
DerefBytes = Base->getPointerDereferenceableBytes(DL, CanBeNull);
T.GlobalState.indicatePessimisticFixpoint();
} else {
const DerefState &DS = AA.getState();
DerefBytes = DS.DerefBytesState.getAssumed();
T.GlobalState &= DS.GlobalState;
}
// For now we do not try to "increase" dereferenceability due to negative
// indices as we first have to come up with code to deal with loops and
// for overflows of the dereferenceable bytes.
int64_t OffsetSExt = Offset.getSExtValue();
if (OffsetSExt < 0)
OffsetSExt = 0;
T.takeAssumedDerefBytesMinimum(
std::max(int64_t(0), DerefBytes - OffsetSExt));
if (this == &AA) {
if (!Stripped) {
// If nothing was stripped IR information is all we got.
T.takeKnownDerefBytesMaximum(
std::max(int64_t(0), DerefBytes - OffsetSExt));
T.indicatePessimisticFixpoint();
} else if (OffsetSExt > 0) {
// If something was stripped but there is circular reasoning we look
// for the offset. If it is positive we basically decrease the
// dereferenceable bytes in a circluar loop now, which will simply
// drive them down to the known value in a very slow way which we
// can accelerate.
T.indicatePessimisticFixpoint();
}
}
return T.isValidState();
};
DerefState T;
if (!genericValueTraversal<AADereferenceable, DerefState>(
A, getIRPosition(), *this, T, VisitValueCB, getCtxI()))
return indicatePessimisticFixpoint();
return clampStateAndIndicateChange(getState(), T);
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
STATS_DECLTRACK_FLOATING_ATTR(dereferenceable)
}
};
/// Dereferenceable attribute for a return value.
struct AADereferenceableReturned final
: AAReturnedFromReturnedValues<AADereferenceable, AADereferenceableImpl> {
AADereferenceableReturned(const IRPosition &IRP, Attributor &A)
: AAReturnedFromReturnedValues<AADereferenceable, AADereferenceableImpl>(
IRP, A) {}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
STATS_DECLTRACK_FNRET_ATTR(dereferenceable)
}
};
/// Dereferenceable attribute for an argument
struct AADereferenceableArgument final
: AAArgumentFromCallSiteArguments<AADereferenceable,
AADereferenceableImpl> {
using Base =
AAArgumentFromCallSiteArguments<AADereferenceable, AADereferenceableImpl>;
AADereferenceableArgument(const IRPosition &IRP, Attributor &A)
: Base(IRP, A) {}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
STATS_DECLTRACK_ARG_ATTR(dereferenceable)
}
};
/// Dereferenceable attribute for a call site argument.
struct AADereferenceableCallSiteArgument final : AADereferenceableFloating {
AADereferenceableCallSiteArgument(const IRPosition &IRP, Attributor &A)
: AADereferenceableFloating(IRP, A) {}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
STATS_DECLTRACK_CSARG_ATTR(dereferenceable)
}
};
/// Dereferenceable attribute deduction for a call site return value.
struct AADereferenceableCallSiteReturned final
: AACallSiteReturnedFromReturned<AADereferenceable, AADereferenceableImpl> {
using Base =
AACallSiteReturnedFromReturned<AADereferenceable, AADereferenceableImpl>;
AADereferenceableCallSiteReturned(const IRPosition &IRP, Attributor &A)
: Base(IRP, A) {}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
STATS_DECLTRACK_CS_ATTR(dereferenceable);
}
};
// ------------------------ Align Argument Attribute ------------------------
static unsigned getKnownAlignForUse(Attributor &A,
AbstractAttribute &QueryingAA,
Value &AssociatedValue, const Use *U,
const Instruction *I, bool &TrackUse) {
// We need to follow common pointer manipulation uses to the accesses they
// feed into.
if (isa<CastInst>(I)) {
// Follow all but ptr2int casts.
TrackUse = !isa<PtrToIntInst>(I);
return 0;
}
if (auto *GEP = dyn_cast<GetElementPtrInst>(I)) {
if (GEP->hasAllConstantIndices()) {
TrackUse = true;
return 0;
}
}
MaybeAlign MA;
if (const auto *CB = dyn_cast<CallBase>(I)) {
if (CB->isBundleOperand(U) || CB->isCallee(U))
return 0;
unsigned ArgNo = CB->getArgOperandNo(U);
IRPosition IRP = IRPosition::callsite_argument(*CB, ArgNo);
// As long as we only use known information there is no need to track
// dependences here.
auto &AlignAA = A.getAAFor<AAAlign>(QueryingAA, IRP,
/* TrackDependence */ false);
MA = MaybeAlign(AlignAA.getKnownAlign());
}
const DataLayout &DL = A.getDataLayout();
const Value *UseV = U->get();
if (auto *SI = dyn_cast<StoreInst>(I)) {
if (SI->getPointerOperand() == UseV)
MA = SI->getAlign();
} else if (auto *LI = dyn_cast<LoadInst>(I)) {
if (LI->getPointerOperand() == UseV)
MA = LI->getAlign();
}
if (!MA || *MA <= 1)
return 0;
unsigned Alignment = MA->value();
int64_t Offset;
if (const Value *Base = GetPointerBaseWithConstantOffset(UseV, Offset, DL)) {
if (Base == &AssociatedValue) {
// BasePointerAddr + Offset = Alignment * Q for some integer Q.
// So we can say that the maximum power of two which is a divisor of
// gcd(Offset, Alignment) is an alignment.
uint32_t gcd =
greatestCommonDivisor(uint32_t(abs((int32_t)Offset)), Alignment);
Alignment = llvm::PowerOf2Floor(gcd);
}
}
return Alignment;
}
struct AAAlignImpl : AAAlign {
AAAlignImpl(const IRPosition &IRP, Attributor &A) : AAAlign(IRP, A) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
SmallVector<Attribute, 4> Attrs;
getAttrs({Attribute::Alignment}, Attrs);
for (const Attribute &Attr : Attrs)
takeKnownMaximum(Attr.getValueAsInt());
Value &V = getAssociatedValue();
// TODO: This is a HACK to avoid getPointerAlignment to introduce a ptr2int
// use of the function pointer. This was caused by D73131. We want to
// avoid this for function pointers especially because we iterate
// their uses and int2ptr is not handled. It is not a correctness
// problem though!
if (!V.getType()->getPointerElementType()->isFunctionTy())
takeKnownMaximum(V.getPointerAlignment(A.getDataLayout()).value());
if (getIRPosition().isFnInterfaceKind() &&
(!getAnchorScope() ||
!A.isFunctionIPOAmendable(*getAssociatedFunction()))) {
indicatePessimisticFixpoint();
return;
}
if (Instruction *CtxI = getCtxI())
followUsesInMBEC(*this, A, getState(), *CtxI);
}
/// See AbstractAttribute::manifest(...).
ChangeStatus manifest(Attributor &A) override {
ChangeStatus LoadStoreChanged = ChangeStatus::UNCHANGED;
// Check for users that allow alignment annotations.
Value &AssociatedValue = getAssociatedValue();
for (const Use &U : AssociatedValue.uses()) {
if (auto *SI = dyn_cast<StoreInst>(U.getUser())) {
if (SI->getPointerOperand() == &AssociatedValue)
if (SI->getAlignment() < getAssumedAlign()) {
STATS_DECLTRACK(AAAlign, Store,
"Number of times alignment added to a store");
SI->setAlignment(Align(getAssumedAlign()));
LoadStoreChanged = ChangeStatus::CHANGED;
}
} else if (auto *LI = dyn_cast<LoadInst>(U.getUser())) {
if (LI->getPointerOperand() == &AssociatedValue)
if (LI->getAlignment() < getAssumedAlign()) {
LI->setAlignment(Align(getAssumedAlign()));
STATS_DECLTRACK(AAAlign, Load,
"Number of times alignment added to a load");
LoadStoreChanged = ChangeStatus::CHANGED;
}
}
}
ChangeStatus Changed = AAAlign::manifest(A);
Align InheritAlign =
getAssociatedValue().getPointerAlignment(A.getDataLayout());
if (InheritAlign >= getAssumedAlign())
return LoadStoreChanged;
return Changed | LoadStoreChanged;
}
// TODO: Provide a helper to determine the implied ABI alignment and check in
// the existing manifest method and a new one for AAAlignImpl that value
// to avoid making the alignment explicit if it did not improve.
/// See AbstractAttribute::getDeducedAttributes
virtual void
getDeducedAttributes(LLVMContext &Ctx,
SmallVectorImpl<Attribute> &Attrs) const override {
if (getAssumedAlign() > 1)
Attrs.emplace_back(
Attribute::getWithAlignment(Ctx, Align(getAssumedAlign())));
}
/// See followUsesInMBEC
bool followUseInMBEC(Attributor &A, const Use *U, const Instruction *I,
AAAlign::StateType &State) {
bool TrackUse = false;
unsigned int KnownAlign =
getKnownAlignForUse(A, *this, getAssociatedValue(), U, I, TrackUse);
State.takeKnownMaximum(KnownAlign);
return TrackUse;
}
/// See AbstractAttribute::getAsStr().
const std::string getAsStr() const override {
return getAssumedAlign() ? ("align<" + std::to_string(getKnownAlign()) +
"-" + std::to_string(getAssumedAlign()) + ">")
: "unknown-align";
}
};
/// Align attribute for a floating value.
struct AAAlignFloating : AAAlignImpl {
AAAlignFloating(const IRPosition &IRP, Attributor &A) : AAAlignImpl(IRP, A) {}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
const DataLayout &DL = A.getDataLayout();
auto VisitValueCB = [&](Value &V, const Instruction *,
AAAlign::StateType &T, bool Stripped) -> bool {
const auto &AA = A.getAAFor<AAAlign>(*this, IRPosition::value(V));
if (!Stripped && this == &AA) {
int64_t Offset;
unsigned Alignment = 1;
if (const Value *Base =
GetPointerBaseWithConstantOffset(&V, Offset, DL)) {
Align PA = Base->getPointerAlignment(DL);
// BasePointerAddr + Offset = Alignment * Q for some integer Q.
// So we can say that the maximum power of two which is a divisor of
// gcd(Offset, Alignment) is an alignment.
uint32_t gcd = greatestCommonDivisor(uint32_t(abs((int32_t)Offset)),
uint32_t(PA.value()));
Alignment = llvm::PowerOf2Floor(gcd);
} else {
Alignment = V.getPointerAlignment(DL).value();
}
// Use only IR information if we did not strip anything.
T.takeKnownMaximum(Alignment);
T.indicatePessimisticFixpoint();
} else {
// Use abstract attribute information.
const AAAlign::StateType &DS = AA.getState();
T ^= DS;
}
return T.isValidState();
};
StateType T;
if (!genericValueTraversal<AAAlign, StateType>(A, getIRPosition(), *this, T,
VisitValueCB, getCtxI()))
return indicatePessimisticFixpoint();
// TODO: If we know we visited all incoming values, thus no are assumed
// dead, we can take the known information from the state T.
return clampStateAndIndicateChange(getState(), T);
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_FLOATING_ATTR(align) }
};
/// Align attribute for function return value.
struct AAAlignReturned final
: AAReturnedFromReturnedValues<AAAlign, AAAlignImpl> {
using Base = AAReturnedFromReturnedValues<AAAlign, AAAlignImpl>;
AAAlignReturned(const IRPosition &IRP, Attributor &A) : Base(IRP, A) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
Base::initialize(A);
Function *F = getAssociatedFunction();
if (!F || F->isDeclaration())
indicatePessimisticFixpoint();
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_FNRET_ATTR(aligned) }
};
/// Align attribute for function argument.
struct AAAlignArgument final
: AAArgumentFromCallSiteArguments<AAAlign, AAAlignImpl> {
using Base = AAArgumentFromCallSiteArguments<AAAlign, AAAlignImpl>;
AAAlignArgument(const IRPosition &IRP, Attributor &A) : Base(IRP, A) {}
/// See AbstractAttribute::manifest(...).
ChangeStatus manifest(Attributor &A) override {
// If the associated argument is involved in a must-tail call we give up
// because we would need to keep the argument alignments of caller and
// callee in-sync. Just does not seem worth the trouble right now.
if (A.getInfoCache().isInvolvedInMustTailCall(*getAssociatedArgument()))
return ChangeStatus::UNCHANGED;
return Base::manifest(A);
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_ARG_ATTR(aligned) }
};
struct AAAlignCallSiteArgument final : AAAlignFloating {
AAAlignCallSiteArgument(const IRPosition &IRP, Attributor &A)
: AAAlignFloating(IRP, A) {}
/// See AbstractAttribute::manifest(...).
ChangeStatus manifest(Attributor &A) override {
// If the associated argument is involved in a must-tail call we give up
// because we would need to keep the argument alignments of caller and
// callee in-sync. Just does not seem worth the trouble right now.
if (Argument *Arg = getAssociatedArgument())
if (A.getInfoCache().isInvolvedInMustTailCall(*Arg))
return ChangeStatus::UNCHANGED;
ChangeStatus Changed = AAAlignImpl::manifest(A);
Align InheritAlign =
getAssociatedValue().getPointerAlignment(A.getDataLayout());
if (InheritAlign >= getAssumedAlign())
Changed = ChangeStatus::UNCHANGED;
return Changed;
}
/// See AbstractAttribute::updateImpl(Attributor &A).
ChangeStatus updateImpl(Attributor &A) override {
ChangeStatus Changed = AAAlignFloating::updateImpl(A);
if (Argument *Arg = getAssociatedArgument()) {
// We only take known information from the argument
// so we do not need to track a dependence.
const auto &ArgAlignAA = A.getAAFor<AAAlign>(
*this, IRPosition::argument(*Arg), /* TrackDependence */ false);
takeKnownMaximum(ArgAlignAA.getKnownAlign());
}
return Changed;
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_CSARG_ATTR(aligned) }
};
/// Align attribute deduction for a call site return value.
struct AAAlignCallSiteReturned final
: AACallSiteReturnedFromReturned<AAAlign, AAAlignImpl> {
using Base = AACallSiteReturnedFromReturned<AAAlign, AAAlignImpl>;
AAAlignCallSiteReturned(const IRPosition &IRP, Attributor &A)
: Base(IRP, A) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
Base::initialize(A);
Function *F = getAssociatedFunction();
if (!F || F->isDeclaration())
indicatePessimisticFixpoint();
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_CS_ATTR(align); }
};
/// ------------------ Function No-Return Attribute ----------------------------
struct AANoReturnImpl : public AANoReturn {
AANoReturnImpl(const IRPosition &IRP, Attributor &A) : AANoReturn(IRP, A) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
AANoReturn::initialize(A);
Function *F = getAssociatedFunction();
if (!F || F->isDeclaration())
indicatePessimisticFixpoint();
}
/// See AbstractAttribute::getAsStr().
const std::string getAsStr() const override {
return getAssumed() ? "noreturn" : "may-return";
}
/// See AbstractAttribute::updateImpl(Attributor &A).
virtual ChangeStatus updateImpl(Attributor &A) override {
auto CheckForNoReturn = [](Instruction &) { return false; };
if (!A.checkForAllInstructions(CheckForNoReturn, *this,
{(unsigned)Instruction::Ret}))
return indicatePessimisticFixpoint();
return ChangeStatus::UNCHANGED;
}
};
struct AANoReturnFunction final : AANoReturnImpl {
AANoReturnFunction(const IRPosition &IRP, Attributor &A)
: AANoReturnImpl(IRP, A) {}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_FN_ATTR(noreturn) }
};
/// NoReturn attribute deduction for a call sites.
struct AANoReturnCallSite final : AANoReturnImpl {
AANoReturnCallSite(const IRPosition &IRP, Attributor &A)
: AANoReturnImpl(IRP, A) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
AANoReturnImpl::initialize(A);
if (Function *F = getAssociatedFunction()) {
const IRPosition &FnPos = IRPosition::function(*F);
auto &FnAA = A.getAAFor<AANoReturn>(*this, FnPos);
if (!FnAA.isAssumedNoReturn())
indicatePessimisticFixpoint();
}
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
// TODO: Once we have call site specific value information we can provide
// call site specific liveness information and then it makes
// sense to specialize attributes for call sites arguments instead of
// redirecting requests to the callee argument.
Function *F = getAssociatedFunction();
const IRPosition &FnPos = IRPosition::function(*F);
auto &FnAA = A.getAAFor<AANoReturn>(*this, FnPos);
return clampStateAndIndicateChange(getState(), FnAA.getState());
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_CS_ATTR(noreturn); }
};
/// ----------------------- Variable Capturing ---------------------------------
/// A class to hold the state of for no-capture attributes.
struct AANoCaptureImpl : public AANoCapture {
AANoCaptureImpl(const IRPosition &IRP, Attributor &A) : AANoCapture(IRP, A) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
if (hasAttr(getAttrKind(), /* IgnoreSubsumingPositions */ true)) {
indicateOptimisticFixpoint();
return;
}
Function *AnchorScope = getAnchorScope();
if (isFnInterfaceKind() &&
(!AnchorScope || !A.isFunctionIPOAmendable(*AnchorScope))) {
indicatePessimisticFixpoint();
return;
}
// You cannot "capture" null in the default address space.
if (isa<ConstantPointerNull>(getAssociatedValue()) &&
getAssociatedValue().getType()->getPointerAddressSpace() == 0) {
indicateOptimisticFixpoint();
return;
}
const Function *F =
isArgumentPosition() ? getAssociatedFunction() : AnchorScope;
// Check what state the associated function can actually capture.
if (F)
determineFunctionCaptureCapabilities(getIRPosition(), *F, *this);
else
indicatePessimisticFixpoint();
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override;
/// see AbstractAttribute::isAssumedNoCaptureMaybeReturned(...).
virtual void
getDeducedAttributes(LLVMContext &Ctx,
SmallVectorImpl<Attribute> &Attrs) const override {
if (!isAssumedNoCaptureMaybeReturned())
return;
if (isArgumentPosition()) {
if (isAssumedNoCapture())
Attrs.emplace_back(Attribute::get(Ctx, Attribute::NoCapture));
else if (ManifestInternal)
Attrs.emplace_back(Attribute::get(Ctx, "no-capture-maybe-returned"));
}
}
/// Set the NOT_CAPTURED_IN_MEM and NOT_CAPTURED_IN_RET bits in \p Known
/// depending on the ability of the function associated with \p IRP to capture
/// state in memory and through "returning/throwing", respectively.
static void determineFunctionCaptureCapabilities(const IRPosition &IRP,
const Function &F,
BitIntegerState &State) {
// TODO: Once we have memory behavior attributes we should use them here.
// If we know we cannot communicate or write to memory, we do not care about
// ptr2int anymore.
if (F.onlyReadsMemory() && F.doesNotThrow() &&
F.getReturnType()->isVoidTy()) {
State.addKnownBits(NO_CAPTURE);
return;
}
// A function cannot capture state in memory if it only reads memory, it can
// however return/throw state and the state might be influenced by the
// pointer value, e.g., loading from a returned pointer might reveal a bit.
if (F.onlyReadsMemory())
State.addKnownBits(NOT_CAPTURED_IN_MEM);
// A function cannot communicate state back if it does not through
// exceptions and doesn not return values.
if (F.doesNotThrow() && F.getReturnType()->isVoidTy())
State.addKnownBits(NOT_CAPTURED_IN_RET);
// Check existing "returned" attributes.
int ArgNo = IRP.getCalleeArgNo();
if (F.doesNotThrow() && ArgNo >= 0) {
for (unsigned u = 0, e = F.arg_size(); u < e; ++u)
if (F.hasParamAttribute(u, Attribute::Returned)) {
if (u == unsigned(ArgNo))
State.removeAssumedBits(NOT_CAPTURED_IN_RET);
else if (F.onlyReadsMemory())
State.addKnownBits(NO_CAPTURE);
else
State.addKnownBits(NOT_CAPTURED_IN_RET);
break;
}
}
}
/// See AbstractState::getAsStr().
const std::string getAsStr() const override {
if (isKnownNoCapture())
return "known not-captured";
if (isAssumedNoCapture())
return "assumed not-captured";
if (isKnownNoCaptureMaybeReturned())
return "known not-captured-maybe-returned";
if (isAssumedNoCaptureMaybeReturned())
return "assumed not-captured-maybe-returned";
return "assumed-captured";
}
};
/// Attributor-aware capture tracker.
struct AACaptureUseTracker final : public CaptureTracker {
/// Create a capture tracker that can lookup in-flight abstract attributes
/// through the Attributor \p A.
///
/// If a use leads to a potential capture, \p CapturedInMemory is set and the
/// search is stopped. If a use leads to a return instruction,
/// \p CommunicatedBack is set to true and \p CapturedInMemory is not changed.
/// If a use leads to a ptr2int which may capture the value,
/// \p CapturedInInteger is set. If a use is found that is currently assumed
/// "no-capture-maybe-returned", the user is added to the \p PotentialCopies
/// set. All values in \p PotentialCopies are later tracked as well. For every
/// explored use we decrement \p RemainingUsesToExplore. Once it reaches 0,
/// the search is stopped with \p CapturedInMemory and \p CapturedInInteger
/// conservatively set to true.
AACaptureUseTracker(Attributor &A, AANoCapture &NoCaptureAA,
const AAIsDead &IsDeadAA, AANoCapture::StateType &State,
SmallVectorImpl<const Value *> &PotentialCopies,
unsigned &RemainingUsesToExplore)
: A(A), NoCaptureAA(NoCaptureAA), IsDeadAA(IsDeadAA), State(State),
PotentialCopies(PotentialCopies),
RemainingUsesToExplore(RemainingUsesToExplore) {}
/// Determine if \p V maybe captured. *Also updates the state!*
bool valueMayBeCaptured(const Value *V) {
if (V->getType()->isPointerTy()) {
PointerMayBeCaptured(V, this);
} else {
State.indicatePessimisticFixpoint();
}
return State.isAssumed(AANoCapture::NO_CAPTURE_MAYBE_RETURNED);
}
/// See CaptureTracker::tooManyUses().
void tooManyUses() override {
State.removeAssumedBits(AANoCapture::NO_CAPTURE);
}
bool isDereferenceableOrNull(Value *O, const DataLayout &DL) override {
if (CaptureTracker::isDereferenceableOrNull(O, DL))
return true;
const auto &DerefAA = A.getAAFor<AADereferenceable>(
NoCaptureAA, IRPosition::value(*O), /* TrackDependence */ true,
DepClassTy::OPTIONAL);
return DerefAA.getAssumedDereferenceableBytes();
}
/// See CaptureTracker::captured(...).
bool captured(const Use *U) override {
Instruction *UInst = cast<Instruction>(U->getUser());
LLVM_DEBUG(dbgs() << "Check use: " << *U->get() << " in " << *UInst
<< "\n");
// Because we may reuse the tracker multiple times we keep track of the
// number of explored uses ourselves as well.
if (RemainingUsesToExplore-- == 0) {
LLVM_DEBUG(dbgs() << " - too many uses to explore!\n");
return isCapturedIn(/* Memory */ true, /* Integer */ true,
/* Return */ true);
}
// Deal with ptr2int by following uses.
if (isa<PtrToIntInst>(UInst)) {
LLVM_DEBUG(dbgs() << " - ptr2int assume the worst!\n");
return valueMayBeCaptured(UInst);
}
// Explicitly catch return instructions.
if (isa<ReturnInst>(UInst))
return isCapturedIn(/* Memory */ false, /* Integer */ false,
/* Return */ true);
// For now we only use special logic for call sites. However, the tracker
// itself knows about a lot of other non-capturing cases already.
auto *CB = dyn_cast<CallBase>(UInst);
if (!CB || !CB->isArgOperand(U))
return isCapturedIn(/* Memory */ true, /* Integer */ true,
/* Return */ true);
unsigned ArgNo = CB->getArgOperandNo(U);
const IRPosition &CSArgPos = IRPosition::callsite_argument(*CB, ArgNo);
// If we have a abstract no-capture attribute for the argument we can use
// it to justify a non-capture attribute here. This allows recursion!
auto &ArgNoCaptureAA = A.getAAFor<AANoCapture>(NoCaptureAA, CSArgPos);
if (ArgNoCaptureAA.isAssumedNoCapture())
return isCapturedIn(/* Memory */ false, /* Integer */ false,
/* Return */ false);
if (ArgNoCaptureAA.isAssumedNoCaptureMaybeReturned()) {
addPotentialCopy(*CB);
return isCapturedIn(/* Memory */ false, /* Integer */ false,
/* Return */ false);
}
// Lastly, we could not find a reason no-capture can be assumed so we don't.
return isCapturedIn(/* Memory */ true, /* Integer */ true,
/* Return */ true);
}
/// Register \p CS as potential copy of the value we are checking.
void addPotentialCopy(CallBase &CB) { PotentialCopies.push_back(&CB); }
/// See CaptureTracker::shouldExplore(...).
bool shouldExplore(const Use *U) override {
// Check liveness and ignore droppable users.
return !U->getUser()->isDroppable() &&
!A.isAssumedDead(*U, &NoCaptureAA, &IsDeadAA);
}
/// Update the state according to \p CapturedInMem, \p CapturedInInt, and
/// \p CapturedInRet, then return the appropriate value for use in the
/// CaptureTracker::captured() interface.
bool isCapturedIn(bool CapturedInMem, bool CapturedInInt,
bool CapturedInRet) {
LLVM_DEBUG(dbgs() << " - captures [Mem " << CapturedInMem << "|Int "
<< CapturedInInt << "|Ret " << CapturedInRet << "]\n");
if (CapturedInMem)
State.removeAssumedBits(AANoCapture::NOT_CAPTURED_IN_MEM);
if (CapturedInInt)
State.removeAssumedBits(AANoCapture::NOT_CAPTURED_IN_INT);
if (CapturedInRet)
State.removeAssumedBits(AANoCapture::NOT_CAPTURED_IN_RET);
return !State.isAssumed(AANoCapture::NO_CAPTURE_MAYBE_RETURNED);
}
private:
/// The attributor providing in-flight abstract attributes.
Attributor &A;
/// The abstract attribute currently updated.
AANoCapture &NoCaptureAA;
/// The abstract liveness state.
const AAIsDead &IsDeadAA;
/// The state currently updated.
AANoCapture::StateType &State;
/// Set of potential copies of the tracked value.
SmallVectorImpl<const Value *> &PotentialCopies;
/// Global counter to limit the number of explored uses.
unsigned &RemainingUsesToExplore;
};
ChangeStatus AANoCaptureImpl::updateImpl(Attributor &A) {
const IRPosition &IRP = getIRPosition();
const Value *V = isArgumentPosition() ? IRP.getAssociatedArgument()
: &IRP.getAssociatedValue();
if (!V)
return indicatePessimisticFixpoint();
const Function *F =
isArgumentPosition() ? IRP.getAssociatedFunction() : IRP.getAnchorScope();
assert(F && "Expected a function!");
const IRPosition &FnPos = IRPosition::function(*F);
const auto &IsDeadAA =
A.getAAFor<AAIsDead>(*this, FnPos, /* TrackDependence */ false);
AANoCapture::StateType T;
// Readonly means we cannot capture through memory.
const auto &FnMemAA =
A.getAAFor<AAMemoryBehavior>(*this, FnPos, /* TrackDependence */ false);
if (FnMemAA.isAssumedReadOnly()) {
T.addKnownBits(NOT_CAPTURED_IN_MEM);
if (FnMemAA.isKnownReadOnly())
addKnownBits(NOT_CAPTURED_IN_MEM);
else
A.recordDependence(FnMemAA, *this, DepClassTy::OPTIONAL);
}
// Make sure all returned values are different than the underlying value.
// TODO: we could do this in a more sophisticated way inside
// AAReturnedValues, e.g., track all values that escape through returns
// directly somehow.
auto CheckReturnedArgs = [&](const AAReturnedValues &RVAA) {
bool SeenConstant = false;
for (auto &It : RVAA.returned_values()) {
if (isa<Constant>(It.first)) {
if (SeenConstant)
return false;
SeenConstant = true;
} else if (!isa<Argument>(It.first) ||
It.first == getAssociatedArgument())
return false;
}
return true;
};
const auto &NoUnwindAA = A.getAAFor<AANoUnwind>(
*this, FnPos, /* TrackDependence */ true, DepClassTy::OPTIONAL);
if (NoUnwindAA.isAssumedNoUnwind()) {
bool IsVoidTy = F->getReturnType()->isVoidTy();
const AAReturnedValues *RVAA =
IsVoidTy ? nullptr
: &A.getAAFor<AAReturnedValues>(*this, FnPos,
/* TrackDependence */ true,
DepClassTy::OPTIONAL);
if (IsVoidTy || CheckReturnedArgs(*RVAA)) {
T.addKnownBits(NOT_CAPTURED_IN_RET);
if (T.isKnown(NOT_CAPTURED_IN_MEM))
return ChangeStatus::UNCHANGED;
if (NoUnwindAA.isKnownNoUnwind() &&
(IsVoidTy || RVAA->getState().isAtFixpoint())) {
addKnownBits(NOT_CAPTURED_IN_RET);
if (isKnown(NOT_CAPTURED_IN_MEM))
return indicateOptimisticFixpoint();
}
}
}
// Use the CaptureTracker interface and logic with the specialized tracker,
// defined in AACaptureUseTracker, that can look at in-flight abstract
// attributes and directly updates the assumed state.
SmallVector<const Value *, 4> PotentialCopies;
unsigned RemainingUsesToExplore =
getDefaultMaxUsesToExploreForCaptureTracking();
AACaptureUseTracker Tracker(A, *this, IsDeadAA, T, PotentialCopies,
RemainingUsesToExplore);
// Check all potential copies of the associated value until we can assume
// none will be captured or we have to assume at least one might be.
unsigned Idx = 0;
PotentialCopies.push_back(V);
while (T.isAssumed(NO_CAPTURE_MAYBE_RETURNED) && Idx < PotentialCopies.size())
Tracker.valueMayBeCaptured(PotentialCopies[Idx++]);
AANoCapture::StateType &S = getState();
auto Assumed = S.getAssumed();
S.intersectAssumedBits(T.getAssumed());
if (!isAssumedNoCaptureMaybeReturned())
return indicatePessimisticFixpoint();
return Assumed == S.getAssumed() ? ChangeStatus::UNCHANGED
: ChangeStatus::CHANGED;
}
/// NoCapture attribute for function arguments.
struct AANoCaptureArgument final : AANoCaptureImpl {
AANoCaptureArgument(const IRPosition &IRP, Attributor &A)
: AANoCaptureImpl(IRP, A) {}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_ARG_ATTR(nocapture) }
};
/// NoCapture attribute for call site arguments.
struct AANoCaptureCallSiteArgument final : AANoCaptureImpl {
AANoCaptureCallSiteArgument(const IRPosition &IRP, Attributor &A)
: AANoCaptureImpl(IRP, A) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
if (Argument *Arg = getAssociatedArgument())
if (Arg->hasByValAttr())
indicateOptimisticFixpoint();
AANoCaptureImpl::initialize(A);
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
// TODO: Once we have call site specific value information we can provide
// call site specific liveness information and then it makes
// sense to specialize attributes for call sites arguments instead of
// redirecting requests to the callee argument.
Argument *Arg = getAssociatedArgument();
if (!Arg)
return indicatePessimisticFixpoint();
const IRPosition &ArgPos = IRPosition::argument(*Arg);
auto &ArgAA = A.getAAFor<AANoCapture>(*this, ArgPos);
return clampStateAndIndicateChange(getState(), ArgAA.getState());
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override{STATS_DECLTRACK_CSARG_ATTR(nocapture)};
};
/// NoCapture attribute for floating values.
struct AANoCaptureFloating final : AANoCaptureImpl {
AANoCaptureFloating(const IRPosition &IRP, Attributor &A)
: AANoCaptureImpl(IRP, A) {}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
STATS_DECLTRACK_FLOATING_ATTR(nocapture)
}
};
/// NoCapture attribute for function return value.
struct AANoCaptureReturned final : AANoCaptureImpl {
AANoCaptureReturned(const IRPosition &IRP, Attributor &A)
: AANoCaptureImpl(IRP, A) {
llvm_unreachable("NoCapture is not applicable to function returns!");
}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
llvm_unreachable("NoCapture is not applicable to function returns!");
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
llvm_unreachable("NoCapture is not applicable to function returns!");
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {}
};
/// NoCapture attribute deduction for a call site return value.
struct AANoCaptureCallSiteReturned final : AANoCaptureImpl {
AANoCaptureCallSiteReturned(const IRPosition &IRP, Attributor &A)
: AANoCaptureImpl(IRP, A) {}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
STATS_DECLTRACK_CSRET_ATTR(nocapture)
}
};
/// ------------------ Value Simplify Attribute ----------------------------
struct AAValueSimplifyImpl : AAValueSimplify {
AAValueSimplifyImpl(const IRPosition &IRP, Attributor &A)
: AAValueSimplify(IRP, A) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
if (getAssociatedValue().getType()->isVoidTy())
indicatePessimisticFixpoint();
}
/// See AbstractAttribute::getAsStr().
const std::string getAsStr() const override {
return getAssumed() ? (getKnown() ? "simplified" : "maybe-simple")
: "not-simple";
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {}
/// See AAValueSimplify::getAssumedSimplifiedValue()
Optional<Value *> getAssumedSimplifiedValue(Attributor &A) const override {
if (!getAssumed())
return const_cast<Value *>(&getAssociatedValue());
return SimplifiedAssociatedValue;
}
/// Helper function for querying AAValueSimplify and updating candicate.
/// \param QueryingValue Value trying to unify with SimplifiedValue
/// \param AccumulatedSimplifiedValue Current simplification result.
static bool checkAndUpdate(Attributor &A, const AbstractAttribute &QueryingAA,
Value &QueryingValue,
Optional<Value *> &AccumulatedSimplifiedValue) {
// FIXME: Add a typecast support.
auto &ValueSimplifyAA = A.getAAFor<AAValueSimplify>(
QueryingAA, IRPosition::value(QueryingValue));
Optional<Value *> QueryingValueSimplified =
ValueSimplifyAA.getAssumedSimplifiedValue(A);
if (!QueryingValueSimplified.hasValue())
return true;
if (!QueryingValueSimplified.getValue())
return false;
Value &QueryingValueSimplifiedUnwrapped =
*QueryingValueSimplified.getValue();
if (AccumulatedSimplifiedValue.hasValue() &&
!isa<UndefValue>(AccumulatedSimplifiedValue.getValue()) &&
!isa<UndefValue>(QueryingValueSimplifiedUnwrapped))
return AccumulatedSimplifiedValue == QueryingValueSimplified;
if (AccumulatedSimplifiedValue.hasValue() &&
isa<UndefValue>(QueryingValueSimplifiedUnwrapped))
return true;
LLVM_DEBUG(dbgs() << "[ValueSimplify] " << QueryingValue
<< " is assumed to be "
<< QueryingValueSimplifiedUnwrapped << "\n");
AccumulatedSimplifiedValue = QueryingValueSimplified;
return true;
}
/// Returns a candidate is found or not
template <typename AAType> bool askSimplifiedValueFor(Attributor &A) {
if (!getAssociatedValue().getType()->isIntegerTy())
return false;
const auto &AA =
A.getAAFor<AAType>(*this, getIRPosition(), /* TrackDependence */ false);
Optional<ConstantInt *> COpt = AA.getAssumedConstantInt(A);
if (!COpt.hasValue()) {
SimplifiedAssociatedValue = llvm::None;
A.recordDependence(AA, *this, DepClassTy::OPTIONAL);
return true;
}
if (auto *C = COpt.getValue()) {
SimplifiedAssociatedValue = C;
A.recordDependence(AA, *this, DepClassTy::OPTIONAL);
return true;
}
return false;
}
bool askSimplifiedValueForOtherAAs(Attributor &A) {
if (askSimplifiedValueFor<AAValueConstantRange>(A))
return true;
if (askSimplifiedValueFor<AAPotentialValues>(A))
return true;
return false;
}
/// See AbstractAttribute::manifest(...).
ChangeStatus manifest(Attributor &A) override {
ChangeStatus Changed = ChangeStatus::UNCHANGED;
if (SimplifiedAssociatedValue.hasValue() &&
!SimplifiedAssociatedValue.getValue())
return Changed;
Value &V = getAssociatedValue();
auto *C = SimplifiedAssociatedValue.hasValue()
? dyn_cast<Constant>(SimplifiedAssociatedValue.getValue())
: UndefValue::get(V.getType());
if (C) {
// We can replace the AssociatedValue with the constant.
if (!V.user_empty() && &V != C && V.getType() == C->getType()) {
LLVM_DEBUG(dbgs() << "[ValueSimplify] " << V << " -> " << *C
<< " :: " << *this << "\n");
if (A.changeValueAfterManifest(V, *C))
Changed = ChangeStatus::CHANGED;
}
}
return Changed | AAValueSimplify::manifest(A);
}
/// See AbstractState::indicatePessimisticFixpoint(...).
ChangeStatus indicatePessimisticFixpoint() override {
// NOTE: Associated value will be returned in a pessimistic fixpoint and is
// regarded as known. That's why`indicateOptimisticFixpoint` is called.
SimplifiedAssociatedValue = &getAssociatedValue();
indicateOptimisticFixpoint();
return ChangeStatus::CHANGED;
}
protected:
// An assumed simplified value. Initially, it is set to Optional::None, which
// means that the value is not clear under current assumption. If in the
// pessimistic state, getAssumedSimplifiedValue doesn't return this value but
// returns orignal associated value.
Optional<Value *> SimplifiedAssociatedValue;
};
struct AAValueSimplifyArgument final : AAValueSimplifyImpl {
AAValueSimplifyArgument(const IRPosition &IRP, Attributor &A)
: AAValueSimplifyImpl(IRP, A) {}
void initialize(Attributor &A) override {
AAValueSimplifyImpl::initialize(A);
if (!getAnchorScope() || getAnchorScope()->isDeclaration())
indicatePessimisticFixpoint();
if (hasAttr({Attribute::InAlloca, Attribute::Preallocated,
Attribute::StructRet, Attribute::Nest},
/* IgnoreSubsumingPositions */ true))
indicatePessimisticFixpoint();
// FIXME: This is a hack to prevent us from propagating function poiner in
// the new pass manager CGSCC pass as it creates call edges the
// CallGraphUpdater cannot handle yet.
Value &V = getAssociatedValue();
if (V.getType()->isPointerTy() &&
V.getType()->getPointerElementType()->isFunctionTy() &&
!A.isModulePass())
indicatePessimisticFixpoint();
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
// Byval is only replacable if it is readonly otherwise we would write into
// the replaced value and not the copy that byval creates implicitly.
Argument *Arg = getAssociatedArgument();
if (Arg->hasByValAttr()) {
// TODO: We probably need to verify synchronization is not an issue, e.g.,
// there is no race by not copying a constant byval.
const auto &MemAA = A.getAAFor<AAMemoryBehavior>(*this, getIRPosition());
if (!MemAA.isAssumedReadOnly())
return indicatePessimisticFixpoint();
}
bool HasValueBefore = SimplifiedAssociatedValue.hasValue();
auto PredForCallSite = [&](AbstractCallSite ACS) {
const IRPosition &ACSArgPos =
IRPosition::callsite_argument(ACS, getCallSiteArgNo());
// Check if a coresponding argument was found or if it is on not
// associated (which can happen for callback calls).
if (ACSArgPos.getPositionKind() == IRPosition::IRP_INVALID)
return false;
// We can only propagate thread independent values through callbacks.
// This is different to direct/indirect call sites because for them we
// know the thread executing the caller and callee is the same. For
// callbacks this is not guaranteed, thus a thread dependent value could
// be different for the caller and callee, making it invalid to propagate.
Value &ArgOp = ACSArgPos.getAssociatedValue();
if (ACS.isCallbackCall())
if (auto *C = dyn_cast<Constant>(&ArgOp))
if (C->isThreadDependent())
return false;
return checkAndUpdate(A, *this, ArgOp, SimplifiedAssociatedValue);
};
bool AllCallSitesKnown;
if (!A.checkForAllCallSites(PredForCallSite, *this, true,
AllCallSitesKnown))
if (!askSimplifiedValueForOtherAAs(A))
return indicatePessimisticFixpoint();
// If a candicate was found in this update, return CHANGED.
return HasValueBefore == SimplifiedAssociatedValue.hasValue()
? ChangeStatus::UNCHANGED
: ChangeStatus ::CHANGED;
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
STATS_DECLTRACK_ARG_ATTR(value_simplify)
}
};
struct AAValueSimplifyReturned : AAValueSimplifyImpl {
AAValueSimplifyReturned(const IRPosition &IRP, Attributor &A)
: AAValueSimplifyImpl(IRP, A) {}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
bool HasValueBefore = SimplifiedAssociatedValue.hasValue();
auto PredForReturned = [&](Value &V) {
return checkAndUpdate(A, *this, V, SimplifiedAssociatedValue);
};
if (!A.checkForAllReturnedValues(PredForReturned, *this))
if (!askSimplifiedValueForOtherAAs(A))
return indicatePessimisticFixpoint();
// If a candicate was found in this update, return CHANGED.
return HasValueBefore == SimplifiedAssociatedValue.hasValue()
? ChangeStatus::UNCHANGED
: ChangeStatus ::CHANGED;
}
ChangeStatus manifest(Attributor &A) override {
ChangeStatus Changed = ChangeStatus::UNCHANGED;
if (SimplifiedAssociatedValue.hasValue() &&
!SimplifiedAssociatedValue.getValue())
return Changed;
Value &V = getAssociatedValue();
auto *C = SimplifiedAssociatedValue.hasValue()
? dyn_cast<Constant>(SimplifiedAssociatedValue.getValue())
: UndefValue::get(V.getType());
if (C) {
auto PredForReturned =
[&](Value &V, const SmallSetVector<ReturnInst *, 4> &RetInsts) {
// We can replace the AssociatedValue with the constant.
if (&V == C || V.getType() != C->getType() || isa<UndefValue>(V))
return true;
for (ReturnInst *RI : RetInsts) {
if (RI->getFunction() != getAnchorScope())
continue;
auto *RC = C;
if (RC->getType() != RI->getReturnValue()->getType())
RC = ConstantExpr::getBitCast(RC,
RI->getReturnValue()->getType());
LLVM_DEBUG(dbgs() << "[ValueSimplify] " << V << " -> " << *RC
<< " in " << *RI << " :: " << *this << "\n");
if (A.changeUseAfterManifest(RI->getOperandUse(0), *RC))
Changed = ChangeStatus::CHANGED;
}
return true;
};
A.checkForAllReturnedValuesAndReturnInsts(PredForReturned, *this);
}
return Changed | AAValueSimplify::manifest(A);
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
STATS_DECLTRACK_FNRET_ATTR(value_simplify)
}
};
struct AAValueSimplifyFloating : AAValueSimplifyImpl {
AAValueSimplifyFloating(const IRPosition &IRP, Attributor &A)
: AAValueSimplifyImpl(IRP, A) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
// FIXME: This might have exposed a SCC iterator update bug in the old PM.
// Needs investigation.
// AAValueSimplifyImpl::initialize(A);
Value &V = getAnchorValue();
// TODO: add other stuffs
if (isa<Constant>(V))
indicatePessimisticFixpoint();
}
/// Check if \p ICmp is an equality comparison (==/!=) with at least one
/// nullptr. If so, try to simplify it using AANonNull on the other operand.
/// Return true if successful, in that case SimplifiedAssociatedValue will be
/// updated and \p Changed is set appropriately.
bool checkForNullPtrCompare(Attributor &A, ICmpInst *ICmp,
ChangeStatus &Changed) {
if (!ICmp)
return false;
if (!ICmp->isEquality())
return false;
// This is a comparison with == or !-. We check for nullptr now.
bool Op0IsNull = isa<ConstantPointerNull>(ICmp->getOperand(0));
bool Op1IsNull = isa<ConstantPointerNull>(ICmp->getOperand(1));
if (!Op0IsNull && !Op1IsNull)
return false;
LLVMContext &Ctx = ICmp->getContext();
// Check for `nullptr ==/!= nullptr` first:
if (Op0IsNull && Op1IsNull) {
Value *NewVal = ConstantInt::get(
Type::getInt1Ty(Ctx), ICmp->getPredicate() == CmpInst::ICMP_EQ);
assert(!SimplifiedAssociatedValue.hasValue() &&
"Did not expect non-fixed value for constant comparison");
SimplifiedAssociatedValue = NewVal;
indicateOptimisticFixpoint();
Changed = ChangeStatus::CHANGED;
return true;
}
// Left is the nullptr ==/!= non-nullptr case. We'll use AANonNull on the
// non-nullptr operand and if we assume it's non-null we can conclude the
// result of the comparison.
assert((Op0IsNull || Op1IsNull) &&
"Expected nullptr versus non-nullptr comparison at this point");
// The index is the operand that we assume is not null.
unsigned PtrIdx = Op0IsNull;
auto &PtrNonNullAA = A.getAAFor<AANonNull>(
*this, IRPosition::value(*ICmp->getOperand(PtrIdx)));
if (!PtrNonNullAA.isAssumedNonNull())
return false;
// The new value depends on the predicate, true for != and false for ==.
Value *NewVal = ConstantInt::get(Type::getInt1Ty(Ctx),
ICmp->getPredicate() == CmpInst::ICMP_NE);
assert((!SimplifiedAssociatedValue.hasValue() ||
SimplifiedAssociatedValue == NewVal) &&
"Did not expect to change value for zero-comparison");
bool HasValueBefore = SimplifiedAssociatedValue.hasValue();
SimplifiedAssociatedValue = NewVal;
if (PtrNonNullAA.isKnownNonNull())
indicateOptimisticFixpoint();
Changed = HasValueBefore ? ChangeStatus::UNCHANGED : ChangeStatus ::CHANGED;
return true;
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
bool HasValueBefore = SimplifiedAssociatedValue.hasValue();
ChangeStatus Changed;
if (checkForNullPtrCompare(A, dyn_cast<ICmpInst>(&getAnchorValue()),
Changed))
return Changed;
auto VisitValueCB = [&](Value &V, const Instruction *CtxI, bool &,
bool Stripped) -> bool {
auto &AA = A.getAAFor<AAValueSimplify>(*this, IRPosition::value(V));
if (!Stripped && this == &AA) {
// TODO: Look the instruction and check recursively.
LLVM_DEBUG(dbgs() << "[ValueSimplify] Can't be stripped more : " << V
<< "\n");
return false;
}
return checkAndUpdate(A, *this, V, SimplifiedAssociatedValue);
};
bool Dummy = false;
if (!genericValueTraversal<AAValueSimplify, bool>(
A, getIRPosition(), *this, Dummy, VisitValueCB, getCtxI(),
/* UseValueSimplify */ false))
if (!askSimplifiedValueForOtherAAs(A))
return indicatePessimisticFixpoint();
// If a candicate was found in this update, return CHANGED.
return HasValueBefore == SimplifiedAssociatedValue.hasValue()
? ChangeStatus::UNCHANGED
: ChangeStatus ::CHANGED;
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
STATS_DECLTRACK_FLOATING_ATTR(value_simplify)
}
};
struct AAValueSimplifyFunction : AAValueSimplifyImpl {
AAValueSimplifyFunction(const IRPosition &IRP, Attributor &A)
: AAValueSimplifyImpl(IRP, A) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
SimplifiedAssociatedValue = &getAnchorValue();
indicateOptimisticFixpoint();
}
/// See AbstractAttribute::initialize(...).
ChangeStatus updateImpl(Attributor &A) override {
llvm_unreachable(
"AAValueSimplify(Function|CallSite)::updateImpl will not be called");
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
STATS_DECLTRACK_FN_ATTR(value_simplify)
}
};
struct AAValueSimplifyCallSite : AAValueSimplifyFunction {
AAValueSimplifyCallSite(const IRPosition &IRP, Attributor &A)
: AAValueSimplifyFunction(IRP, A) {}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
STATS_DECLTRACK_CS_ATTR(value_simplify)
}
};
struct AAValueSimplifyCallSiteReturned : AAValueSimplifyReturned {
AAValueSimplifyCallSiteReturned(const IRPosition &IRP, Attributor &A)
: AAValueSimplifyReturned(IRP, A) {}
/// See AbstractAttribute::manifest(...).
ChangeStatus manifest(Attributor &A) override {
return AAValueSimplifyImpl::manifest(A);
}
void trackStatistics() const override {
STATS_DECLTRACK_CSRET_ATTR(value_simplify)
}
};
struct AAValueSimplifyCallSiteArgument : AAValueSimplifyFloating {
AAValueSimplifyCallSiteArgument(const IRPosition &IRP, Attributor &A)
: AAValueSimplifyFloating(IRP, A) {}
/// See AbstractAttribute::manifest(...).
ChangeStatus manifest(Attributor &A) override {
ChangeStatus Changed = ChangeStatus::UNCHANGED;
if (SimplifiedAssociatedValue.hasValue() &&
!SimplifiedAssociatedValue.getValue())
return Changed;
Value &V = getAssociatedValue();
auto *C = SimplifiedAssociatedValue.hasValue()
? dyn_cast<Constant>(SimplifiedAssociatedValue.getValue())
: UndefValue::get(V.getType());
if (C) {
Use &U = cast<CallBase>(&getAnchorValue())
->getArgOperandUse(getCallSiteArgNo());
// We can replace the AssociatedValue with the constant.
if (&V != C && V.getType() == C->getType()) {
if (A.changeUseAfterManifest(U, *C))
Changed = ChangeStatus::CHANGED;
}
}
return Changed | AAValueSimplify::manifest(A);
}
void trackStatistics() const override {
STATS_DECLTRACK_CSARG_ATTR(value_simplify)
}
};
/// ----------------------- Heap-To-Stack Conversion ---------------------------
struct AAHeapToStackImpl : public AAHeapToStack {
AAHeapToStackImpl(const IRPosition &IRP, Attributor &A)
: AAHeapToStack(IRP, A) {}
const std::string getAsStr() const override {
return "[H2S] Mallocs: " + std::to_string(MallocCalls.size());
}
ChangeStatus manifest(Attributor &A) override {
assert(getState().isValidState() &&
"Attempted to manifest an invalid state!");
ChangeStatus HasChanged = ChangeStatus::UNCHANGED;
Function *F = getAnchorScope();
const auto *TLI = A.getInfoCache().getTargetLibraryInfoForFunction(*F);
for (Instruction *MallocCall : MallocCalls) {
// This malloc cannot be replaced.
if (BadMallocCalls.count(MallocCall))
continue;
for (Instruction *FreeCall : FreesForMalloc[MallocCall]) {
LLVM_DEBUG(dbgs() << "H2S: Removing free call: " << *FreeCall << "\n");
A.deleteAfterManifest(*FreeCall);
HasChanged = ChangeStatus::CHANGED;
}
LLVM_DEBUG(dbgs() << "H2S: Removing malloc call: " << *MallocCall
<< "\n");
Align Alignment;
Constant *Size;
if (isCallocLikeFn(MallocCall, TLI)) {
auto *Num = cast<ConstantInt>(MallocCall->getOperand(0));
auto *SizeT = cast<ConstantInt>(MallocCall->getOperand(1));
APInt TotalSize = SizeT->getValue() * Num->getValue();
Size =
ConstantInt::get(MallocCall->getOperand(0)->getType(), TotalSize);
} else if (isAlignedAllocLikeFn(MallocCall, TLI)) {
Size = cast<ConstantInt>(MallocCall->getOperand(1));
Alignment = MaybeAlign(cast<ConstantInt>(MallocCall->getOperand(0))
->getValue()
.getZExtValue())
.valueOrOne();
} else {
Size = cast<ConstantInt>(MallocCall->getOperand(0));
}
unsigned AS = cast<PointerType>(MallocCall->getType())->getAddressSpace();
Instruction *AI =
new AllocaInst(Type::getInt8Ty(F->getContext()), AS, Size, Alignment,
"", MallocCall->getNextNode());
if (AI->getType() != MallocCall->getType())
AI = new BitCastInst(AI, MallocCall->getType(), "malloc_bc",
AI->getNextNode());
A.changeValueAfterManifest(*MallocCall, *AI);
if (auto *II = dyn_cast<InvokeInst>(MallocCall)) {
auto *NBB = II->getNormalDest();
BranchInst::Create(NBB, MallocCall->getParent());
A.deleteAfterManifest(*MallocCall);
} else {
A.deleteAfterManifest(*MallocCall);
}
// Zero out the allocated memory if it was a calloc.
if (isCallocLikeFn(MallocCall, TLI)) {
auto *BI = new BitCastInst(AI, MallocCall->getType(), "calloc_bc",
AI->getNextNode());
Value *Ops[] = {
BI, ConstantInt::get(F->getContext(), APInt(8, 0, false)), Size,
ConstantInt::get(Type::getInt1Ty(F->getContext()), false)};
Type *Tys[] = {BI->getType(), MallocCall->getOperand(0)->getType()};
Module *M = F->getParent();
Function *Fn = Intrinsic::getDeclaration(M, Intrinsic::memset, Tys);
CallInst::Create(Fn, Ops, "", BI->getNextNode());
}
HasChanged = ChangeStatus::CHANGED;
}
return HasChanged;
}
/// Collection of all malloc calls in a function.
SmallSetVector<Instruction *, 4> MallocCalls;
/// Collection of malloc calls that cannot be converted.
DenseSet<const Instruction *> BadMallocCalls;
/// A map for each malloc call to the set of associated free calls.
DenseMap<Instruction *, SmallPtrSet<Instruction *, 4>> FreesForMalloc;
ChangeStatus updateImpl(Attributor &A) override;
};
ChangeStatus AAHeapToStackImpl::updateImpl(Attributor &A) {
const Function *F = getAnchorScope();
const auto *TLI = A.getInfoCache().getTargetLibraryInfoForFunction(*F);
MustBeExecutedContextExplorer &Explorer =
A.getInfoCache().getMustBeExecutedContextExplorer();
auto FreeCheck = [&](Instruction &I) {
const auto &Frees = FreesForMalloc.lookup(&I);
if (Frees.size() != 1)
return false;
Instruction *UniqueFree = *Frees.begin();
return Explorer.findInContextOf(UniqueFree, I.getNextNode());
};
auto UsesCheck = [&](Instruction &I) {
bool ValidUsesOnly = true;
bool MustUse = true;
auto Pred = [&](const Use &U, bool &Follow) -> bool {
Instruction *UserI = cast<Instruction>(U.getUser());
if (isa<LoadInst>(UserI))
return true;
if (auto *SI = dyn_cast<StoreInst>(UserI)) {
if (SI->getValueOperand() == U.get()) {
LLVM_DEBUG(dbgs()
<< "[H2S] escaping store to memory: " << *UserI << "\n");
ValidUsesOnly = false;
} else {
// A store into the malloc'ed memory is fine.
}
return true;
}
if (auto *CB = dyn_cast<CallBase>(UserI)) {
if (!CB->isArgOperand(&U) || CB->isLifetimeStartOrEnd())
return true;
// Record malloc.
if (isFreeCall(UserI, TLI)) {
if (MustUse) {
FreesForMalloc[&I].insert(UserI);
} else {
LLVM_DEBUG(dbgs() << "[H2S] free potentially on different mallocs: "
<< *UserI << "\n");
ValidUsesOnly = false;
}
return true;
}
unsigned ArgNo = CB->getArgOperandNo(&U);
const auto &NoCaptureAA = A.getAAFor<AANoCapture>(
*this, IRPosition::callsite_argument(*CB, ArgNo));
// If a callsite argument use is nofree, we are fine.
const auto &ArgNoFreeAA = A.getAAFor<AANoFree>(
*this, IRPosition::callsite_argument(*CB, ArgNo));
if (!NoCaptureAA.isAssumedNoCapture() ||
!ArgNoFreeAA.isAssumedNoFree()) {
LLVM_DEBUG(dbgs() << "[H2S] Bad user: " << *UserI << "\n");
ValidUsesOnly = false;
}
return true;
}
if (isa<GetElementPtrInst>(UserI) || isa<BitCastInst>(UserI) ||
isa<PHINode>(UserI) || isa<SelectInst>(UserI)) {
MustUse &= !(isa<PHINode>(UserI) || isa<SelectInst>(UserI));
Follow = true;
return true;
}
// Unknown user for which we can not track uses further (in a way that
// makes sense).
LLVM_DEBUG(dbgs() << "[H2S] Unknown user: " << *UserI << "\n");
ValidUsesOnly = false;
return true;
};
A.checkForAllUses(Pred, *this, I);
return ValidUsesOnly;
};
auto MallocCallocCheck = [&](Instruction &I) {
if (BadMallocCalls.count(&I))
return true;
bool IsMalloc = isMallocLikeFn(&I, TLI);
bool IsAlignedAllocLike = isAlignedAllocLikeFn(&I, TLI);
bool IsCalloc = !IsMalloc && isCallocLikeFn(&I, TLI);
if (!IsMalloc && !IsAlignedAllocLike && !IsCalloc) {
BadMallocCalls.insert(&I);
return true;
}
if (IsMalloc) {
if (auto *Size = dyn_cast<ConstantInt>(I.getOperand(0)))
if (Size->getValue().ule(MaxHeapToStackSize))
if (UsesCheck(I) || FreeCheck(I)) {
MallocCalls.insert(&I);
return true;
}
} else if (IsAlignedAllocLike && isa<ConstantInt>(I.getOperand(0))) {
// Only if the alignment and sizes are constant.
if (auto *Size = dyn_cast<ConstantInt>(I.getOperand(1)))
if (Size->getValue().ule(MaxHeapToStackSize))
if (UsesCheck(I) || FreeCheck(I)) {
MallocCalls.insert(&I);
return true;
}
} else if (IsCalloc) {
bool Overflow = false;
if (auto *Num = dyn_cast<ConstantInt>(I.getOperand(0)))
if (auto *Size = dyn_cast<ConstantInt>(I.getOperand(1)))
if ((Size->getValue().umul_ov(Num->getValue(), Overflow))
.ule(MaxHeapToStackSize))
if (!Overflow && (UsesCheck(I) || FreeCheck(I))) {
MallocCalls.insert(&I);
return true;
}
}
BadMallocCalls.insert(&I);
return true;
};
size_t NumBadMallocs = BadMallocCalls.size();
A.checkForAllCallLikeInstructions(MallocCallocCheck, *this);
if (NumBadMallocs != BadMallocCalls.size())
return ChangeStatus::CHANGED;
return ChangeStatus::UNCHANGED;
}
struct AAHeapToStackFunction final : public AAHeapToStackImpl {
AAHeapToStackFunction(const IRPosition &IRP, Attributor &A)
: AAHeapToStackImpl(IRP, A) {}
/// See AbstractAttribute::trackStatistics().
void trackStatistics() const override {
STATS_DECL(
MallocCalls, Function,
"Number of malloc/calloc/aligned_alloc calls converted to allocas");
for (auto *C : MallocCalls)
if (!BadMallocCalls.count(C))
++BUILD_STAT_NAME(MallocCalls, Function);
}
};
/// ----------------------- Privatizable Pointers ------------------------------
struct AAPrivatizablePtrImpl : public AAPrivatizablePtr {
AAPrivatizablePtrImpl(const IRPosition &IRP, Attributor &A)
: AAPrivatizablePtr(IRP, A), PrivatizableType(llvm::None) {}
ChangeStatus indicatePessimisticFixpoint() override {
AAPrivatizablePtr::indicatePessimisticFixpoint();
PrivatizableType = nullptr;
return ChangeStatus::CHANGED;
}
/// Identify the type we can chose for a private copy of the underlying
/// argument. None means it is not clear yet, nullptr means there is none.
virtual Optional<Type *> identifyPrivatizableType(Attributor &A) = 0;
/// Return a privatizable type that encloses both T0 and T1.
/// TODO: This is merely a stub for now as we should manage a mapping as well.
Optional<Type *> combineTypes(Optional<Type *> T0, Optional<Type *> T1) {
if (!T0.hasValue())
return T1;
if (!T1.hasValue())
return T0;
if (T0 == T1)
return T0;
return nullptr;
}
Optional<Type *> getPrivatizableType() const override {
return PrivatizableType;
}
const std::string getAsStr() const override {
return isAssumedPrivatizablePtr() ? "[priv]" : "[no-priv]";
}
protected:
Optional<Type *> PrivatizableType;
};
// TODO: Do this for call site arguments (probably also other values) as well.
struct AAPrivatizablePtrArgument final : public AAPrivatizablePtrImpl {
AAPrivatizablePtrArgument(const IRPosition &IRP, Attributor &A)
: AAPrivatizablePtrImpl(IRP, A) {}
/// See AAPrivatizablePtrImpl::identifyPrivatizableType(...)
Optional<Type *> identifyPrivatizableType(Attributor &A) override {
// If this is a byval argument and we know all the call sites (so we can
// rewrite them), there is no need to check them explicitly.
bool AllCallSitesKnown;
if (getIRPosition().hasAttr(Attribute::ByVal) &&
A.checkForAllCallSites([](AbstractCallSite ACS) { return true; }, *this,
true, AllCallSitesKnown))
return getAssociatedValue().getType()->getPointerElementType();
Optional<Type *> Ty;
unsigned ArgNo = getIRPosition().getCallSiteArgNo();
// Make sure the associated call site argument has the same type at all call
// sites and it is an allocation we know is safe to privatize, for now that
// means we only allow alloca instructions.
// TODO: We can additionally analyze the accesses in the callee to create
// the type from that information instead. That is a little more
// involved and will be done in a follow up patch.
auto CallSiteCheck = [&](AbstractCallSite ACS) {
IRPosition ACSArgPos = IRPosition::callsite_argument(ACS, ArgNo);
// Check if a coresponding argument was found or if it is one not
// associated (which can happen for callback calls).
if (ACSArgPos.getPositionKind() == IRPosition::IRP_INVALID)
return false;
// Check that all call sites agree on a type.
auto &PrivCSArgAA = A.getAAFor<AAPrivatizablePtr>(*this, ACSArgPos);
Optional<Type *> CSTy = PrivCSArgAA.getPrivatizableType();
LLVM_DEBUG({
dbgs() << "[AAPrivatizablePtr] ACSPos: " << ACSArgPos << ", CSTy: ";
if (CSTy.hasValue() && CSTy.getValue())
CSTy.getValue()->print(dbgs());
else if (CSTy.hasValue())
dbgs() << "<nullptr>";
else
dbgs() << "<none>";
});
Ty = combineTypes(Ty, CSTy);
LLVM_DEBUG({
dbgs() << " : New Type: ";
if (Ty.hasValue() && Ty.getValue())
Ty.getValue()->print(dbgs());
else if (Ty.hasValue())
dbgs() << "<nullptr>";
else
dbgs() << "<none>";
dbgs() << "\n";
});
return !Ty.hasValue() || Ty.getValue();
};
if (!A.checkForAllCallSites(CallSiteCheck, *this, true, AllCallSitesKnown))
return nullptr;
return Ty;
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
PrivatizableType = identifyPrivatizableType(A);
if (!PrivatizableType.hasValue())
return ChangeStatus::UNCHANGED;
if (!PrivatizableType.getValue())
return indicatePessimisticFixpoint();
// The dependence is optional so we don't give up once we give up on the
// alignment.
A.getAAFor<AAAlign>(*this, IRPosition::value(getAssociatedValue()),
/* TrackDependence */ true, DepClassTy::OPTIONAL);
// Avoid arguments with padding for now.
if (!getIRPosition().hasAttr(Attribute::ByVal) &&
!ArgumentPromotionPass::isDenselyPacked(PrivatizableType.getValue(),
A.getInfoCache().getDL())) {
LLVM_DEBUG(dbgs() << "[AAPrivatizablePtr] Padding detected\n");
return indicatePessimisticFixpoint();
}
// Verify callee and caller agree on how the promoted argument would be
// passed.
// TODO: The use of the ArgumentPromotion interface here is ugly, we need a
// specialized form of TargetTransformInfo::areFunctionArgsABICompatible
// which doesn't require the arguments ArgumentPromotion wanted to pass.
Function &Fn = *getIRPosition().getAnchorScope();
SmallPtrSet<Argument *, 1> ArgsToPromote, Dummy;
ArgsToPromote.insert(getAssociatedArgument());
const auto *TTI =
A.getInfoCache().getAnalysisResultForFunction<TargetIRAnalysis>(Fn);
if (!TTI ||
!ArgumentPromotionPass::areFunctionArgsABICompatible(
Fn, *TTI, ArgsToPromote, Dummy) ||
ArgsToPromote.empty()) {
LLVM_DEBUG(
dbgs() << "[AAPrivatizablePtr] ABI incompatibility detected for "
<< Fn.getName() << "\n");
return indicatePessimisticFixpoint();
}
// Collect the types that will replace the privatizable type in the function
// signature.
SmallVector<Type *, 16> ReplacementTypes;
identifyReplacementTypes(PrivatizableType.getValue(), ReplacementTypes);
// Register a rewrite of the argument.
Argument *Arg = getAssociatedArgument();
if (!A.isValidFunctionSignatureRewrite(*Arg, ReplacementTypes)) {
LLVM_DEBUG(dbgs() << "[AAPrivatizablePtr] Rewrite not valid\n");
return indicatePessimisticFixpoint();
}
unsigned ArgNo = Arg->getArgNo();
// Helper to check if for the given call site the associated argument is
// passed to a callback where the privatization would be different.
auto IsCompatiblePrivArgOfCallback = [&](CallBase &CB) {
SmallVector<const Use *, 4> CallbackUses;
AbstractCallSite::getCallbackUses(CB, CallbackUses);
for (const Use *U : CallbackUses) {
AbstractCallSite CBACS(U);
assert(CBACS && CBACS.isCallbackCall());
for (Argument &CBArg : CBACS.getCalledFunction()->args()) {
int CBArgNo = CBACS.getCallArgOperandNo(CBArg);
LLVM_DEBUG({
dbgs()
<< "[AAPrivatizablePtr] Argument " << *Arg
<< "check if can be privatized in the context of its parent ("
<< Arg->getParent()->getName()
<< ")\n[AAPrivatizablePtr] because it is an argument in a "
"callback ("
<< CBArgNo << "@" << CBACS.getCalledFunction()->getName()
<< ")\n[AAPrivatizablePtr] " << CBArg << " : "
<< CBACS.getCallArgOperand(CBArg) << " vs "
<< CB.getArgOperand(ArgNo) << "\n"
<< "[AAPrivatizablePtr] " << CBArg << " : "
<< CBACS.getCallArgOperandNo(CBArg) << " vs " << ArgNo << "\n";
});
if (CBArgNo != int(ArgNo))
continue;
const auto &CBArgPrivAA =
A.getAAFor<AAPrivatizablePtr>(*this, IRPosition::argument(CBArg));
if (CBArgPrivAA.isValidState()) {
auto CBArgPrivTy = CBArgPrivAA.getPrivatizableType();
if (!CBArgPrivTy.hasValue())
continue;
if (CBArgPrivTy.getValue() == PrivatizableType)
continue;
}
LLVM_DEBUG({
dbgs() << "[AAPrivatizablePtr] Argument " << *Arg
<< " cannot be privatized in the context of its parent ("
<< Arg->getParent()->getName()
<< ")\n[AAPrivatizablePtr] because it is an argument in a "
"callback ("
<< CBArgNo << "@" << CBACS.getCalledFunction()->getName()
<< ").\n[AAPrivatizablePtr] for which the argument "
"privatization is not compatible.\n";
});
return false;
}
}
return true;
};
// Helper to check if for the given call site the associated argument is
// passed to a direct call where the privatization would be different.
auto IsCompatiblePrivArgOfDirectCS = [&](AbstractCallSite ACS) {
CallBase *DC = cast<CallBase>(ACS.getInstruction());
int DCArgNo = ACS.getCallArgOperandNo(ArgNo);
assert(DCArgNo >= 0 && unsigned(DCArgNo) < DC->getNumArgOperands() &&
"Expected a direct call operand for callback call operand");
LLVM_DEBUG({
dbgs() << "[AAPrivatizablePtr] Argument " << *Arg
<< " check if be privatized in the context of its parent ("
<< Arg->getParent()->getName()
<< ")\n[AAPrivatizablePtr] because it is an argument in a "
"direct call of ("
<< DCArgNo << "@" << DC->getCalledFunction()->getName()
<< ").\n";
});
Function *DCCallee = DC->getCalledFunction();
if (unsigned(DCArgNo) < DCCallee->arg_size()) {
const auto &DCArgPrivAA = A.getAAFor<AAPrivatizablePtr>(
*this, IRPosition::argument(*DCCallee->getArg(DCArgNo)));
if (DCArgPrivAA.isValidState()) {
auto DCArgPrivTy = DCArgPrivAA.getPrivatizableType();
if (!DCArgPrivTy.hasValue())
return true;
if (DCArgPrivTy.getValue() == PrivatizableType)
return true;
}
}
LLVM_DEBUG({
dbgs() << "[AAPrivatizablePtr] Argument " << *Arg
<< " cannot be privatized in the context of its parent ("
<< Arg->getParent()->getName()
<< ")\n[AAPrivatizablePtr] because it is an argument in a "
"direct call of ("
<< ACS.getInstruction()->getCalledFunction()->getName()
<< ").\n[AAPrivatizablePtr] for which the argument "
"privatization is not compatible.\n";
});
return false;
};
// Helper to check if the associated argument is used at the given abstract
// call site in a way that is incompatible with the privatization assumed
// here.
auto IsCompatiblePrivArgOfOtherCallSite = [&](AbstractCallSite ACS) {
if (ACS.isDirectCall())
return IsCompatiblePrivArgOfCallback(*ACS.getInstruction());
if (ACS.isCallbackCall())
return IsCompatiblePrivArgOfDirectCS(ACS);
return false;
};
bool AllCallSitesKnown;
if (!A.checkForAllCallSites(IsCompatiblePrivArgOfOtherCallSite, *this, true,
AllCallSitesKnown))
return indicatePessimisticFixpoint();
return ChangeStatus::UNCHANGED;
}
/// Given a type to private \p PrivType, collect the constituates (which are
/// used) in \p ReplacementTypes.
static void
identifyReplacementTypes(Type *PrivType,
SmallVectorImpl<Type *> &ReplacementTypes) {
// TODO: For now we expand the privatization type to the fullest which can
// lead to dead arguments that need to be removed later.
assert(PrivType && "Expected privatizable type!");
// Traverse the type, extract constituate types on the outermost level.
if (auto *PrivStructType = dyn_cast<StructType>(PrivType)) {
for (unsigned u = 0, e = PrivStructType->getNumElements(); u < e; u++)
ReplacementTypes.push_back(PrivStructType->getElementType(u));
} else if (auto *PrivArrayType = dyn_cast<ArrayType>(PrivType)) {
ReplacementTypes.append(PrivArrayType->getNumElements(),
PrivArrayType->getElementType());
} else {
ReplacementTypes.push_back(PrivType);
}
}
/// Initialize \p Base according to the type \p PrivType at position \p IP.
/// The values needed are taken from the arguments of \p F starting at
/// position \p ArgNo.
static void createInitialization(Type *PrivType, Value &Base, Function &F,
unsigned ArgNo, Instruction &IP) {
assert(PrivType && "Expected privatizable type!");
IRBuilder<NoFolder> IRB(&IP);
const DataLayout &DL = F.getParent()->getDataLayout();
// Traverse the type, build GEPs and stores.
if (auto *PrivStructType = dyn_cast<StructType>(PrivType)) {
const StructLayout *PrivStructLayout = DL.getStructLayout(PrivStructType);
for (unsigned u = 0, e = PrivStructType->getNumElements(); u < e; u++) {
Type *PointeeTy = PrivStructType->getElementType(u)->getPointerTo();
Value *Ptr = constructPointer(
PointeeTy, &Base, PrivStructLayout->getElementOffset(u), IRB, DL);
new StoreInst(F.getArg(ArgNo + u), Ptr, &IP);
}
} else if (auto *PrivArrayType = dyn_cast<ArrayType>(PrivType)) {
Type *PointeeTy = PrivArrayType->getElementType();
Type *PointeePtrTy = PointeeTy->getPointerTo();
uint64_t PointeeTySize = DL.getTypeStoreSize(PointeeTy);
for (unsigned u = 0, e = PrivArrayType->getNumElements(); u < e; u++) {
Value *Ptr =
constructPointer(PointeePtrTy, &Base, u * PointeeTySize, IRB, DL);
new StoreInst(F.getArg(ArgNo + u), Ptr, &IP);
}
} else {
new StoreInst(F.getArg(ArgNo), &Base, &IP);
}
}
/// Extract values from \p Base according to the type \p PrivType at the
/// call position \p ACS. The values are appended to \p ReplacementValues.
void createReplacementValues(Align Alignment, Type *PrivType,
AbstractCallSite ACS, Value *Base,
SmallVectorImpl<Value *> &ReplacementValues) {
assert(Base && "Expected base value!");
assert(PrivType && "Expected privatizable type!");
Instruction *IP = ACS.getInstruction();
IRBuilder<NoFolder> IRB(IP);
const DataLayout &DL = IP->getModule()->getDataLayout();
if (Base->getType()->getPointerElementType() != PrivType)
Base = BitCastInst::CreateBitOrPointerCast(Base, PrivType->getPointerTo(),
"", ACS.getInstruction());
// Traverse the type, build GEPs and loads.
if (auto *PrivStructType = dyn_cast<StructType>(PrivType)) {
const StructLayout *PrivStructLayout = DL.getStructLayout(PrivStructType);
for (unsigned u = 0, e = PrivStructType->getNumElements(); u < e; u++) {
Type *PointeeTy = PrivStructType->getElementType(u);
Value *Ptr =
constructPointer(PointeeTy->getPointerTo(), Base,
PrivStructLayout->getElementOffset(u), IRB, DL);
LoadInst *L = new LoadInst(PointeeTy, Ptr, "", IP);
L->setAlignment(Alignment);
ReplacementValues.push_back(L);
}
} else if (auto *PrivArrayType = dyn_cast<ArrayType>(PrivType)) {
Type *PointeeTy = PrivArrayType->getElementType();
uint64_t PointeeTySize = DL.getTypeStoreSize(PointeeTy);
Type *PointeePtrTy = PointeeTy->getPointerTo();
for (unsigned u = 0, e = PrivArrayType->getNumElements(); u < e; u++) {
Value *Ptr =
constructPointer(PointeePtrTy, Base, u * PointeeTySize, IRB, DL);
LoadInst *L = new LoadInst(PointeeTy, Ptr, "", IP);
L->setAlignment(Alignment);
ReplacementValues.push_back(L);
}
} else {
LoadInst *L = new LoadInst(PrivType, Base, "", IP);
L->setAlignment(Alignment);
ReplacementValues.push_back(L);
}
}
/// See AbstractAttribute::manifest(...)
ChangeStatus manifest(Attributor &A) override {
if (!PrivatizableType.hasValue())
return ChangeStatus::UNCHANGED;
assert(PrivatizableType.getValue() && "Expected privatizable type!");
// Collect all tail calls in the function as we cannot allow new allocas to
// escape into tail recursion.
// TODO: Be smarter about new allocas escaping into tail calls.
SmallVector<CallInst *, 16> TailCalls;
if (!A.checkForAllInstructions(
[&](Instruction &I) {
CallInst &CI = cast<CallInst>(I);
if (CI.isTailCall())
TailCalls.push_back(&CI);
return true;
},
*this, {Instruction::Call}))
return ChangeStatus::UNCHANGED;
Argument *Arg = getAssociatedArgument();
// Query AAAlign attribute for alignment of associated argument to
// determine the best alignment of loads.
const auto &AlignAA = A.getAAFor<AAAlign>(*this, IRPosition::value(*Arg));
// Callback to repair the associated function. A new alloca is placed at the
// beginning and initialized with the values passed through arguments. The
// new alloca replaces the use of the old pointer argument.
Attributor::ArgumentReplacementInfo::CalleeRepairCBTy FnRepairCB =
[=](const Attributor::ArgumentReplacementInfo &ARI,
Function &ReplacementFn, Function::arg_iterator ArgIt) {
BasicBlock &EntryBB = ReplacementFn.getEntryBlock();
Instruction *IP = &*EntryBB.getFirstInsertionPt();
Instruction *AI = new AllocaInst(PrivatizableType.getValue(), 0,
Arg->getName() + ".priv", IP);
createInitialization(PrivatizableType.getValue(), *AI, ReplacementFn,
ArgIt->getArgNo(), *IP);
if (AI->getType() != Arg->getType())
AI =
BitCastInst::CreateBitOrPointerCast(AI, Arg->getType(), "", IP);
Arg->replaceAllUsesWith(AI);
for (CallInst *CI : TailCalls)
CI->setTailCall(false);
};
// Callback to repair a call site of the associated function. The elements
// of the privatizable type are loaded prior to the call and passed to the
// new function version.
Attributor::ArgumentReplacementInfo::ACSRepairCBTy ACSRepairCB =
[=, &AlignAA](const Attributor::ArgumentReplacementInfo &ARI,
AbstractCallSite ACS,
SmallVectorImpl<Value *> &NewArgOperands) {
// When no alignment is specified for the load instruction,
// natural alignment is assumed.
createReplacementValues(
assumeAligned(AlignAA.getAssumedAlign()),
PrivatizableType.getValue(), ACS,
ACS.getCallArgOperand(ARI.getReplacedArg().getArgNo()),
NewArgOperands);
};
// Collect the types that will replace the privatizable type in the function
// signature.
SmallVector<Type *, 16> ReplacementTypes;
identifyReplacementTypes(PrivatizableType.getValue(), ReplacementTypes);
// Register a rewrite of the argument.
if (A.registerFunctionSignatureRewrite(*Arg, ReplacementTypes,
std::move(FnRepairCB),
std::move(ACSRepairCB)))
return ChangeStatus::CHANGED;
return ChangeStatus::UNCHANGED;
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
STATS_DECLTRACK_ARG_ATTR(privatizable_ptr);
}
};
struct AAPrivatizablePtrFloating : public AAPrivatizablePtrImpl {
AAPrivatizablePtrFloating(const IRPosition &IRP, Attributor &A)
: AAPrivatizablePtrImpl(IRP, A) {}
/// See AbstractAttribute::initialize(...).
virtual void initialize(Attributor &A) override {
// TODO: We can privatize more than arguments.
indicatePessimisticFixpoint();
}
ChangeStatus updateImpl(Attributor &A) override {
llvm_unreachable("AAPrivatizablePtr(Floating|Returned|CallSiteReturned)::"
"updateImpl will not be called");
}
/// See AAPrivatizablePtrImpl::identifyPrivatizableType(...)
Optional<Type *> identifyPrivatizableType(Attributor &A) override {
Value *Obj = getUnderlyingObject(&getAssociatedValue());
if (!Obj) {
LLVM_DEBUG(dbgs() << "[AAPrivatizablePtr] No underlying object found!\n");
return nullptr;
}
if (auto *AI = dyn_cast<AllocaInst>(Obj))
if (auto *CI = dyn_cast<ConstantInt>(AI->getArraySize()))
if (CI->isOne())
return Obj->getType()->getPointerElementType();
if (auto *Arg = dyn_cast<Argument>(Obj)) {
auto &PrivArgAA =
A.getAAFor<AAPrivatizablePtr>(*this, IRPosition::argument(*Arg));
if (PrivArgAA.isAssumedPrivatizablePtr())
return Obj->getType()->getPointerElementType();
}
LLVM_DEBUG(dbgs() << "[AAPrivatizablePtr] Underlying object neither valid "
"alloca nor privatizable argument: "
<< *Obj << "!\n");
return nullptr;
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
STATS_DECLTRACK_FLOATING_ATTR(privatizable_ptr);
}
};
struct AAPrivatizablePtrCallSiteArgument final
: public AAPrivatizablePtrFloating {
AAPrivatizablePtrCallSiteArgument(const IRPosition &IRP, Attributor &A)
: AAPrivatizablePtrFloating(IRP, A) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
if (getIRPosition().hasAttr(Attribute::ByVal))
indicateOptimisticFixpoint();
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
PrivatizableType = identifyPrivatizableType(A);
if (!PrivatizableType.hasValue())
return ChangeStatus::UNCHANGED;
if (!PrivatizableType.getValue())
return indicatePessimisticFixpoint();
const IRPosition &IRP = getIRPosition();
auto &NoCaptureAA = A.getAAFor<AANoCapture>(*this, IRP);
if (!NoCaptureAA.isAssumedNoCapture()) {
LLVM_DEBUG(dbgs() << "[AAPrivatizablePtr] pointer might be captured!\n");
return indicatePessimisticFixpoint();
}
auto &NoAliasAA = A.getAAFor<AANoAlias>(*this, IRP);
if (!NoAliasAA.isAssumedNoAlias()) {
LLVM_DEBUG(dbgs() << "[AAPrivatizablePtr] pointer might alias!\n");
return indicatePessimisticFixpoint();
}
const auto &MemBehaviorAA = A.getAAFor<AAMemoryBehavior>(*this, IRP);
if (!MemBehaviorAA.isAssumedReadOnly()) {
LLVM_DEBUG(dbgs() << "[AAPrivatizablePtr] pointer is written!\n");
return indicatePessimisticFixpoint();
}
return ChangeStatus::UNCHANGED;
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
STATS_DECLTRACK_CSARG_ATTR(privatizable_ptr);
}
};
struct AAPrivatizablePtrCallSiteReturned final
: public AAPrivatizablePtrFloating {
AAPrivatizablePtrCallSiteReturned(const IRPosition &IRP, Attributor &A)
: AAPrivatizablePtrFloating(IRP, A) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
// TODO: We can privatize more than arguments.
indicatePessimisticFixpoint();
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
STATS_DECLTRACK_CSRET_ATTR(privatizable_ptr);
}
};
struct AAPrivatizablePtrReturned final : public AAPrivatizablePtrFloating {
AAPrivatizablePtrReturned(const IRPosition &IRP, Attributor &A)
: AAPrivatizablePtrFloating(IRP, A) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
// TODO: We can privatize more than arguments.
indicatePessimisticFixpoint();
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
STATS_DECLTRACK_FNRET_ATTR(privatizable_ptr);
}
};
/// -------------------- Memory Behavior Attributes ----------------------------
/// Includes read-none, read-only, and write-only.
/// ----------------------------------------------------------------------------
struct AAMemoryBehaviorImpl : public AAMemoryBehavior {
AAMemoryBehaviorImpl(const IRPosition &IRP, Attributor &A)
: AAMemoryBehavior(IRP, A) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
intersectAssumedBits(BEST_STATE);
getKnownStateFromValue(getIRPosition(), getState());
AAMemoryBehavior::initialize(A);
}
/// Return the memory behavior information encoded in the IR for \p IRP.
static void getKnownStateFromValue(const IRPosition &IRP,
BitIntegerState &State,
bool IgnoreSubsumingPositions = false) {
SmallVector<Attribute, 2> Attrs;
IRP.getAttrs(AttrKinds, Attrs, IgnoreSubsumingPositions);
for (const Attribute &Attr : Attrs) {
switch (Attr.getKindAsEnum()) {
case Attribute::ReadNone:
State.addKnownBits(NO_ACCESSES);
break;
case Attribute::ReadOnly:
State.addKnownBits(NO_WRITES);
break;
case Attribute::WriteOnly:
State.addKnownBits(NO_READS);
break;
default:
llvm_unreachable("Unexpected attribute!");
}
}
if (auto *I = dyn_cast<Instruction>(&IRP.getAnchorValue())) {
if (!I->mayReadFromMemory())
State.addKnownBits(NO_READS);
if (!I->mayWriteToMemory())
State.addKnownBits(NO_WRITES);
}
}
/// See AbstractAttribute::getDeducedAttributes(...).
void getDeducedAttributes(LLVMContext &Ctx,
SmallVectorImpl<Attribute> &Attrs) const override {
assert(Attrs.size() == 0);
if (isAssumedReadNone())
Attrs.push_back(Attribute::get(Ctx, Attribute::ReadNone));
else if (isAssumedReadOnly())
Attrs.push_back(Attribute::get(Ctx, Attribute::ReadOnly));
else if (isAssumedWriteOnly())
Attrs.push_back(Attribute::get(Ctx, Attribute::WriteOnly));
assert(Attrs.size() <= 1);
}
/// See AbstractAttribute::manifest(...).
ChangeStatus manifest(Attributor &A) override {
if (hasAttr(Attribute::ReadNone, /* IgnoreSubsumingPositions */ true))
return ChangeStatus::UNCHANGED;
const IRPosition &IRP = getIRPosition();
// Check if we would improve the existing attributes first.
SmallVector<Attribute, 4> DeducedAttrs;
getDeducedAttributes(IRP.getAnchorValue().getContext(), DeducedAttrs);
if (llvm::all_of(DeducedAttrs, [&](const Attribute &Attr) {
return IRP.hasAttr(Attr.getKindAsEnum(),
/* IgnoreSubsumingPositions */ true);
}))
return ChangeStatus::UNCHANGED;
// Clear existing attributes.
IRP.removeAttrs(AttrKinds);
// Use the generic manifest method.
return IRAttribute::manifest(A);
}
/// See AbstractState::getAsStr().
const std::string getAsStr() const override {
if (isAssumedReadNone())
return "readnone";
if (isAssumedReadOnly())
return "readonly";
if (isAssumedWriteOnly())
return "writeonly";
return "may-read/write";
}
/// The set of IR attributes AAMemoryBehavior deals with.
static const Attribute::AttrKind AttrKinds[3];
};
const Attribute::AttrKind AAMemoryBehaviorImpl::AttrKinds[] = {
Attribute::ReadNone, Attribute::ReadOnly, Attribute::WriteOnly};
/// Memory behavior attribute for a floating value.
struct AAMemoryBehaviorFloating : AAMemoryBehaviorImpl {
AAMemoryBehaviorFloating(const IRPosition &IRP, Attributor &A)
: AAMemoryBehaviorImpl(IRP, A) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
AAMemoryBehaviorImpl::initialize(A);
addUsesOf(A, getAssociatedValue());
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override;
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
if (isAssumedReadNone())
STATS_DECLTRACK_FLOATING_ATTR(readnone)
else if (isAssumedReadOnly())
STATS_DECLTRACK_FLOATING_ATTR(readonly)
else if (isAssumedWriteOnly())
STATS_DECLTRACK_FLOATING_ATTR(writeonly)
}
private:
/// Return true if users of \p UserI might access the underlying
/// variable/location described by \p U and should therefore be analyzed.
bool followUsersOfUseIn(Attributor &A, const Use *U,
const Instruction *UserI);
/// Update the state according to the effect of use \p U in \p UserI.
void analyzeUseIn(Attributor &A, const Use *U, const Instruction *UserI);
protected:
/// Add the uses of \p V to the `Uses` set we look at during the update step.
void addUsesOf(Attributor &A, const Value &V);
/// Container for (transitive) uses of the associated argument.
SmallVector<const Use *, 8> Uses;
/// Set to remember the uses we already traversed.
SmallPtrSet<const Use *, 8> Visited;
};
/// Memory behavior attribute for function argument.
struct AAMemoryBehaviorArgument : AAMemoryBehaviorFloating {
AAMemoryBehaviorArgument(const IRPosition &IRP, Attributor &A)
: AAMemoryBehaviorFloating(IRP, A) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
intersectAssumedBits(BEST_STATE);
const IRPosition &IRP = getIRPosition();
// TODO: Make IgnoreSubsumingPositions a property of an IRAttribute so we
// can query it when we use has/getAttr. That would allow us to reuse the
// initialize of the base class here.
bool HasByVal =
IRP.hasAttr({Attribute::ByVal}, /* IgnoreSubsumingPositions */ true);
getKnownStateFromValue(IRP, getState(),
/* IgnoreSubsumingPositions */ HasByVal);
// Initialize the use vector with all direct uses of the associated value.
Argument *Arg = getAssociatedArgument();
if (!Arg || !A.isFunctionIPOAmendable(*(Arg->getParent()))) {
indicatePessimisticFixpoint();
} else {
addUsesOf(A, *Arg);
}
}
ChangeStatus manifest(Attributor &A) override {
// TODO: Pointer arguments are not supported on vectors of pointers yet.
if (!getAssociatedValue().getType()->isPointerTy())
return ChangeStatus::UNCHANGED;
// TODO: From readattrs.ll: "inalloca parameters are always
// considered written"
if (hasAttr({Attribute::InAlloca, Attribute::Preallocated})) {
removeKnownBits(NO_WRITES);
removeAssumedBits(NO_WRITES);
}
return AAMemoryBehaviorFloating::manifest(A);
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
if (isAssumedReadNone())
STATS_DECLTRACK_ARG_ATTR(readnone)
else if (isAssumedReadOnly())
STATS_DECLTRACK_ARG_ATTR(readonly)
else if (isAssumedWriteOnly())
STATS_DECLTRACK_ARG_ATTR(writeonly)
}
};
struct AAMemoryBehaviorCallSiteArgument final : AAMemoryBehaviorArgument {
AAMemoryBehaviorCallSiteArgument(const IRPosition &IRP, Attributor &A)
: AAMemoryBehaviorArgument(IRP, A) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
// If we don't have an associated attribute this is either a variadic call
// or an indirect call, either way, nothing to do here.
Argument *Arg = getAssociatedArgument();
if (!Arg) {
indicatePessimisticFixpoint();
return;
}
if (Arg->hasByValAttr()) {
addKnownBits(NO_WRITES);
removeKnownBits(NO_READS);
removeAssumedBits(NO_READS);
}
AAMemoryBehaviorArgument::initialize(A);
if (getAssociatedFunction()->isDeclaration())
indicatePessimisticFixpoint();
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
// TODO: Once we have call site specific value information we can provide
// call site specific liveness liveness information and then it makes
// sense to specialize attributes for call sites arguments instead of
// redirecting requests to the callee argument.
Argument *Arg = getAssociatedArgument();
const IRPosition &ArgPos = IRPosition::argument(*Arg);
auto &ArgAA = A.getAAFor<AAMemoryBehavior>(*this, ArgPos);
return clampStateAndIndicateChange(getState(), ArgAA.getState());
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
if (isAssumedReadNone())
STATS_DECLTRACK_CSARG_ATTR(readnone)
else if (isAssumedReadOnly())
STATS_DECLTRACK_CSARG_ATTR(readonly)
else if (isAssumedWriteOnly())
STATS_DECLTRACK_CSARG_ATTR(writeonly)
}
};
/// Memory behavior attribute for a call site return position.
struct AAMemoryBehaviorCallSiteReturned final : AAMemoryBehaviorFloating {
AAMemoryBehaviorCallSiteReturned(const IRPosition &IRP, Attributor &A)
: AAMemoryBehaviorFloating(IRP, A) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
AAMemoryBehaviorImpl::initialize(A);
Function *F = getAssociatedFunction();
if (!F || F->isDeclaration())
indicatePessimisticFixpoint();
}
/// See AbstractAttribute::manifest(...).
ChangeStatus manifest(Attributor &A) override {
// We do not annotate returned values.
return ChangeStatus::UNCHANGED;
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {}
};
/// An AA to represent the memory behavior function attributes.
struct AAMemoryBehaviorFunction final : public AAMemoryBehaviorImpl {
AAMemoryBehaviorFunction(const IRPosition &IRP, Attributor &A)
: AAMemoryBehaviorImpl(IRP, A) {}
/// See AbstractAttribute::updateImpl(Attributor &A).
virtual ChangeStatus updateImpl(Attributor &A) override;
/// See AbstractAttribute::manifest(...).
ChangeStatus manifest(Attributor &A) override {
Function &F = cast<Function>(getAnchorValue());
if (isAssumedReadNone()) {
F.removeFnAttr(Attribute::ArgMemOnly);
F.removeFnAttr(Attribute::InaccessibleMemOnly);
F.removeFnAttr(Attribute::InaccessibleMemOrArgMemOnly);
}
return AAMemoryBehaviorImpl::manifest(A);
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
if (isAssumedReadNone())
STATS_DECLTRACK_FN_ATTR(readnone)
else if (isAssumedReadOnly())
STATS_DECLTRACK_FN_ATTR(readonly)
else if (isAssumedWriteOnly())
STATS_DECLTRACK_FN_ATTR(writeonly)
}
};
/// AAMemoryBehavior attribute for call sites.
struct AAMemoryBehaviorCallSite final : AAMemoryBehaviorImpl {
AAMemoryBehaviorCallSite(const IRPosition &IRP, Attributor &A)
: AAMemoryBehaviorImpl(IRP, A) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
AAMemoryBehaviorImpl::initialize(A);
Function *F = getAssociatedFunction();
if (!F || F->isDeclaration())
indicatePessimisticFixpoint();
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
// TODO: Once we have call site specific value information we can provide
// call site specific liveness liveness information and then it makes
// sense to specialize attributes for call sites arguments instead of
// redirecting requests to the callee argument.
Function *F = getAssociatedFunction();
const IRPosition &FnPos = IRPosition::function(*F);
auto &FnAA = A.getAAFor<AAMemoryBehavior>(*this, FnPos);
return clampStateAndIndicateChange(getState(), FnAA.getState());
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
if (isAssumedReadNone())
STATS_DECLTRACK_CS_ATTR(readnone)
else if (isAssumedReadOnly())
STATS_DECLTRACK_CS_ATTR(readonly)
else if (isAssumedWriteOnly())
STATS_DECLTRACK_CS_ATTR(writeonly)
}
};
ChangeStatus AAMemoryBehaviorFunction::updateImpl(Attributor &A) {
// The current assumed state used to determine a change.
auto AssumedState = getAssumed();
auto CheckRWInst = [&](Instruction &I) {
// If the instruction has an own memory behavior state, use it to restrict
// the local state. No further analysis is required as the other memory
// state is as optimistic as it gets.
if (const auto *CB = dyn_cast<CallBase>(&I)) {
const auto &MemBehaviorAA = A.getAAFor<AAMemoryBehavior>(
*this, IRPosition::callsite_function(*CB));
intersectAssumedBits(MemBehaviorAA.getAssumed());
return !isAtFixpoint();
}
// Remove access kind modifiers if necessary.
if (I.mayReadFromMemory())
removeAssumedBits(NO_READS);
if (I.mayWriteToMemory())
removeAssumedBits(NO_WRITES);
return !isAtFixpoint();
};
if (!A.checkForAllReadWriteInstructions(CheckRWInst, *this))
return indicatePessimisticFixpoint();
return (AssumedState != getAssumed()) ? ChangeStatus::CHANGED
: ChangeStatus::UNCHANGED;
}
ChangeStatus AAMemoryBehaviorFloating::updateImpl(Attributor &A) {
const IRPosition &IRP = getIRPosition();
const IRPosition &FnPos = IRPosition::function_scope(IRP);
AAMemoryBehavior::StateType &S = getState();
// First, check the function scope. We take the known information and we avoid
// work if the assumed information implies the current assumed information for
// this attribute. This is a valid for all but byval arguments.
Argument *Arg = IRP.getAssociatedArgument();
AAMemoryBehavior::base_t FnMemAssumedState =
AAMemoryBehavior::StateType::getWorstState();
if (!Arg || !Arg->hasByValAttr()) {
const auto &FnMemAA = A.getAAFor<AAMemoryBehavior>(
*this, FnPos, /* TrackDependence */ true, DepClassTy::OPTIONAL);
FnMemAssumedState = FnMemAA.getAssumed();
S.addKnownBits(FnMemAA.getKnown());
if ((S.getAssumed() & FnMemAA.getAssumed()) == S.getAssumed())
return ChangeStatus::UNCHANGED;
}
// Make sure the value is not captured (except through "return"), if
// it is, any information derived would be irrelevant anyway as we cannot
// check the potential aliases introduced by the capture. However, no need
// to fall back to anythign less optimistic than the function state.
const auto &ArgNoCaptureAA = A.getAAFor<AANoCapture>(
*this, IRP, /* TrackDependence */ true, DepClassTy::OPTIONAL);
if (!ArgNoCaptureAA.isAssumedNoCaptureMaybeReturned()) {
S.intersectAssumedBits(FnMemAssumedState);
return ChangeStatus::CHANGED;
}
// The current assumed state used to determine a change.
auto AssumedState = S.getAssumed();
// Liveness information to exclude dead users.
// TODO: Take the FnPos once we have call site specific liveness information.
const auto &LivenessAA = A.getAAFor<AAIsDead>(
*this, IRPosition::function(*IRP.getAssociatedFunction()),
/* TrackDependence */ false);
// Visit and expand uses until all are analyzed or a fixpoint is reached.
for (unsigned i = 0; i < Uses.size() && !isAtFixpoint(); i++) {
const Use *U = Uses[i];
Instruction *UserI = cast<Instruction>(U->getUser());
LLVM_DEBUG(dbgs() << "[AAMemoryBehavior] Use: " << **U << " in " << *UserI
<< " [Dead: " << (A.isAssumedDead(*U, this, &LivenessAA))
<< "]\n");
if (A.isAssumedDead(*U, this, &LivenessAA))
continue;
// Droppable users, e.g., llvm::assume does not actually perform any action.
if (UserI->isDroppable())
continue;
// Check if the users of UserI should also be visited.
if (followUsersOfUseIn(A, U, UserI))
addUsesOf(A, *UserI);
// If UserI might touch memory we analyze the use in detail.
if (UserI->mayReadOrWriteMemory())
analyzeUseIn(A, U, UserI);
}
return (AssumedState != getAssumed()) ? ChangeStatus::CHANGED
: ChangeStatus::UNCHANGED;
}
void AAMemoryBehaviorFloating::addUsesOf(Attributor &A, const Value &V) {
SmallVector<const Use *, 8> WL;
for (const Use &U : V.uses())
WL.push_back(&U);
while (!WL.empty()) {
const Use *U = WL.pop_back_val();
if (!Visited.insert(U).second)
continue;
const Instruction *UserI = cast<Instruction>(U->getUser());
if (UserI->mayReadOrWriteMemory()) {
Uses.push_back(U);
continue;
}
if (!followUsersOfUseIn(A, U, UserI))
continue;
for (const Use &UU : UserI->uses())
WL.push_back(&UU);
}
}
bool AAMemoryBehaviorFloating::followUsersOfUseIn(Attributor &A, const Use *U,
const Instruction *UserI) {
// The loaded value is unrelated to the pointer argument, no need to
// follow the users of the load.
if (isa<LoadInst>(UserI))
return false;
// By default we follow all uses assuming UserI might leak information on U,
// we have special handling for call sites operands though.
const auto *CB = dyn_cast<CallBase>(UserI);
if (!CB || !CB->isArgOperand(U))
return true;
// If the use is a call argument known not to be captured, the users of
// the call do not need to be visited because they have to be unrelated to
// the input. Note that this check is not trivial even though we disallow
// general capturing of the underlying argument. The reason is that the
// call might the argument "through return", which we allow and for which we
// need to check call users.
if (U->get()->getType()->isPointerTy()) {
unsigned ArgNo = CB->getArgOperandNo(U);
const auto &ArgNoCaptureAA = A.getAAFor<AANoCapture>(
*this, IRPosition::callsite_argument(*CB, ArgNo),
/* TrackDependence */ true, DepClassTy::OPTIONAL);
return !ArgNoCaptureAA.isAssumedNoCapture();
}
return true;
}
void AAMemoryBehaviorFloating::analyzeUseIn(Attributor &A, const Use *U,
const Instruction *UserI) {
assert(UserI->mayReadOrWriteMemory());
switch (UserI->getOpcode()) {
default:
// TODO: Handle all atomics and other side-effect operations we know of.
break;
case Instruction::Load:
// Loads cause the NO_READS property to disappear.
removeAssumedBits(NO_READS);
return;
case Instruction::Store:
// Stores cause the NO_WRITES property to disappear if the use is the
// pointer operand. Note that we do assume that capturing was taken care of
// somewhere else.
if (cast<StoreInst>(UserI)->getPointerOperand() == U->get())
removeAssumedBits(NO_WRITES);
return;
case Instruction::Call:
case Instruction::CallBr:
case Instruction::Invoke: {
// For call sites we look at the argument memory behavior attribute (this
// could be recursive!) in order to restrict our own state.
const auto *CB = cast<CallBase>(UserI);
// Give up on operand bundles.
if (CB->isBundleOperand(U)) {
indicatePessimisticFixpoint();
return;
}
// Calling a function does read the function pointer, maybe write it if the
// function is self-modifying.
if (CB->isCallee(U)) {
removeAssumedBits(NO_READS);
break;
}
// Adjust the possible access behavior based on the information on the
// argument.
IRPosition Pos;
if (U->get()->getType()->isPointerTy())
Pos = IRPosition::callsite_argument(*CB, CB->getArgOperandNo(U));
else
Pos = IRPosition::callsite_function(*CB);
const auto &MemBehaviorAA = A.getAAFor<AAMemoryBehavior>(
*this, Pos,
/* TrackDependence */ true, DepClassTy::OPTIONAL);
// "assumed" has at most the same bits as the MemBehaviorAA assumed
// and at least "known".
intersectAssumedBits(MemBehaviorAA.getAssumed());
return;
}
};
// Generally, look at the "may-properties" and adjust the assumed state if we
// did not trigger special handling before.
if (UserI->mayReadFromMemory())
removeAssumedBits(NO_READS);
if (UserI->mayWriteToMemory())
removeAssumedBits(NO_WRITES);
}
} // namespace
/// -------------------- Memory Locations Attributes ---------------------------
/// Includes read-none, argmemonly, inaccessiblememonly,
/// inaccessiblememorargmemonly
/// ----------------------------------------------------------------------------
std::string AAMemoryLocation::getMemoryLocationsAsStr(
AAMemoryLocation::MemoryLocationsKind MLK) {
if (0 == (MLK & AAMemoryLocation::NO_LOCATIONS))
return "all memory";
if (MLK == AAMemoryLocation::NO_LOCATIONS)
return "no memory";
std::string S = "memory:";
if (0 == (MLK & AAMemoryLocation::NO_LOCAL_MEM))
S += "stack,";
if (0 == (MLK & AAMemoryLocation::NO_CONST_MEM))
S += "constant,";
if (0 == (MLK & AAMemoryLocation::NO_GLOBAL_INTERNAL_MEM))
S += "internal global,";
if (0 == (MLK & AAMemoryLocation::NO_GLOBAL_EXTERNAL_MEM))
S += "external global,";
if (0 == (MLK & AAMemoryLocation::NO_ARGUMENT_MEM))
S += "argument,";
if (0 == (MLK & AAMemoryLocation::NO_INACCESSIBLE_MEM))
S += "inaccessible,";
if (0 == (MLK & AAMemoryLocation::NO_MALLOCED_MEM))
S += "malloced,";
if (0 == (MLK & AAMemoryLocation::NO_UNKOWN_MEM))
S += "unknown,";
S.pop_back();
return S;
}
namespace {
struct AAMemoryLocationImpl : public AAMemoryLocation {
AAMemoryLocationImpl(const IRPosition &IRP, Attributor &A)
: AAMemoryLocation(IRP, A), Allocator(A.Allocator) {
for (unsigned u = 0; u < llvm::CTLog2<VALID_STATE>(); ++u)
AccessKind2Accesses[u] = nullptr;
}
~AAMemoryLocationImpl() {
// The AccessSets are allocated via a BumpPtrAllocator, we call
// the destructor manually.
for (unsigned u = 0; u < llvm::CTLog2<VALID_STATE>(); ++u)
if (AccessKind2Accesses[u])
AccessKind2Accesses[u]->~AccessSet();
}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
intersectAssumedBits(BEST_STATE);
getKnownStateFromValue(A, getIRPosition(), getState());
AAMemoryLocation::initialize(A);
}
/// Return the memory behavior information encoded in the IR for \p IRP.
static void getKnownStateFromValue(Attributor &A, const IRPosition &IRP,
BitIntegerState &State,
bool IgnoreSubsumingPositions = false) {
// For internal functions we ignore `argmemonly` and
// `inaccessiblememorargmemonly` as we might break it via interprocedural
// constant propagation. It is unclear if this is the best way but it is
// unlikely this will cause real performance problems. If we are deriving
// attributes for the anchor function we even remove the attribute in
// addition to ignoring it.
bool UseArgMemOnly = true;
Function *AnchorFn = IRP.getAnchorScope();
if (AnchorFn && A.isRunOn(*AnchorFn))
UseArgMemOnly = !AnchorFn->hasLocalLinkage();
SmallVector<Attribute, 2> Attrs;
IRP.getAttrs(AttrKinds, Attrs, IgnoreSubsumingPositions);
for (const Attribute &Attr : Attrs) {
switch (Attr.getKindAsEnum()) {
case Attribute::ReadNone:
State.addKnownBits(NO_LOCAL_MEM | NO_CONST_MEM);
break;
case Attribute::InaccessibleMemOnly:
State.addKnownBits(inverseLocation(NO_INACCESSIBLE_MEM, true, true));
break;
case Attribute::ArgMemOnly:
if (UseArgMemOnly)
State.addKnownBits(inverseLocation(NO_ARGUMENT_MEM, true, true));
else
IRP.removeAttrs({Attribute::ArgMemOnly});
break;
case Attribute::InaccessibleMemOrArgMemOnly:
if (UseArgMemOnly)
State.addKnownBits(inverseLocation(
NO_INACCESSIBLE_MEM | NO_ARGUMENT_MEM, true, true));
else
IRP.removeAttrs({Attribute::InaccessibleMemOrArgMemOnly});
break;
default:
llvm_unreachable("Unexpected attribute!");
}
}
}
/// See AbstractAttribute::getDeducedAttributes(...).
void getDeducedAttributes(LLVMContext &Ctx,
SmallVectorImpl<Attribute> &Attrs) const override {
assert(Attrs.size() == 0);
if (isAssumedReadNone()) {
Attrs.push_back(Attribute::get(Ctx, Attribute::ReadNone));
} else if (getIRPosition().getPositionKind() == IRPosition::IRP_FUNCTION) {
if (isAssumedInaccessibleMemOnly())
Attrs.push_back(Attribute::get(Ctx, Attribute::InaccessibleMemOnly));
else if (isAssumedArgMemOnly())
Attrs.push_back(Attribute::get(Ctx, Attribute::ArgMemOnly));
else if (isAssumedInaccessibleOrArgMemOnly())
Attrs.push_back(
Attribute::get(Ctx, Attribute::InaccessibleMemOrArgMemOnly));
}
assert(Attrs.size() <= 1);
}
/// See AbstractAttribute::manifest(...).
ChangeStatus manifest(Attributor &A) override {
const IRPosition &IRP = getIRPosition();
// Check if we would improve the existing attributes first.
SmallVector<Attribute, 4> DeducedAttrs;
getDeducedAttributes(IRP.getAnchorValue().getContext(), DeducedAttrs);
if (llvm::all_of(DeducedAttrs, [&](const Attribute &Attr) {
return IRP.hasAttr(Attr.getKindAsEnum(),
/* IgnoreSubsumingPositions */ true);
}))
return ChangeStatus::UNCHANGED;
// Clear existing attributes.
IRP.removeAttrs(AttrKinds);
if (isAssumedReadNone())
IRP.removeAttrs(AAMemoryBehaviorImpl::AttrKinds);
// Use the generic manifest method.
return IRAttribute::manifest(A);
}
/// See AAMemoryLocation::checkForAllAccessesToMemoryKind(...).
bool checkForAllAccessesToMemoryKind(
function_ref<bool(const Instruction *, const Value *, AccessKind,
MemoryLocationsKind)>
Pred,
MemoryLocationsKind RequestedMLK) const override {
if (!isValidState())
return false;
MemoryLocationsKind AssumedMLK = getAssumedNotAccessedLocation();
if (AssumedMLK == NO_LOCATIONS)
return true;
unsigned Idx = 0;
for (MemoryLocationsKind CurMLK = 1; CurMLK < NO_LOCATIONS;
CurMLK *= 2, ++Idx) {
if (CurMLK & RequestedMLK)
continue;
if (const AccessSet *Accesses = AccessKind2Accesses[Idx])
for (const AccessInfo &AI : *Accesses)
if (!Pred(AI.I, AI.Ptr, AI.Kind, CurMLK))
return false;
}
return true;
}
ChangeStatus indicatePessimisticFixpoint() override {
// If we give up and indicate a pessimistic fixpoint this instruction will
// become an access for all potential access kinds:
// TODO: Add pointers for argmemonly and globals to improve the results of
// checkForAllAccessesToMemoryKind.
bool Changed = false;
MemoryLocationsKind KnownMLK = getKnown();
Instruction *I = dyn_cast<Instruction>(&getAssociatedValue());
for (MemoryLocationsKind CurMLK = 1; CurMLK < NO_LOCATIONS; CurMLK *= 2)
if (!(CurMLK & KnownMLK))
updateStateAndAccessesMap(getState(), CurMLK, I, nullptr, Changed,
getAccessKindFromInst(I));
return AAMemoryLocation::indicatePessimisticFixpoint();
}
protected:
/// Helper struct to tie together an instruction that has a read or write
/// effect with the pointer it accesses (if any).
struct AccessInfo {
/// The instruction that caused the access.
const Instruction *I;
/// The base pointer that is accessed, or null if unknown.
const Value *Ptr;
/// The kind of access (read/write/read+write).
AccessKind Kind;
bool operator==(const AccessInfo &RHS) const {
return I == RHS.I && Ptr == RHS.Ptr && Kind == RHS.Kind;
}
bool operator()(const AccessInfo &LHS, const AccessInfo &RHS) const {
if (LHS.I != RHS.I)
return LHS.I < RHS.I;
if (LHS.Ptr != RHS.Ptr)
return LHS.Ptr < RHS.Ptr;
if (LHS.Kind != RHS.Kind)
return LHS.Kind < RHS.Kind;
return false;
}
};
/// Mapping from *single* memory location kinds, e.g., LOCAL_MEM with the
/// value of NO_LOCAL_MEM, to the accesses encountered for this memory kind.
using AccessSet = SmallSet<AccessInfo, 2, AccessInfo>;
AccessSet *AccessKind2Accesses[llvm::CTLog2<VALID_STATE>()];
/// Categorize the pointer arguments of CB that might access memory in
/// AccessedLoc and update the state and access map accordingly.
void
categorizeArgumentPointerLocations(Attributor &A, CallBase &CB,
AAMemoryLocation::StateType &AccessedLocs,
bool &Changed);
/// Return the kind(s) of location that may be accessed by \p V.
AAMemoryLocation::MemoryLocationsKind
categorizeAccessedLocations(Attributor &A, Instruction &I, bool &Changed);
/// Return the access kind as determined by \p I.
AccessKind getAccessKindFromInst(const Instruction *I) {
AccessKind AK = READ_WRITE;
if (I) {
AK = I->mayReadFromMemory() ? READ : NONE;
AK = AccessKind(AK | (I->mayWriteToMemory() ? WRITE : NONE));
}
return AK;
}
/// Update the state \p State and the AccessKind2Accesses given that \p I is
/// an access of kind \p AK to a \p MLK memory location with the access
/// pointer \p Ptr.
void updateStateAndAccessesMap(AAMemoryLocation::StateType &State,
MemoryLocationsKind MLK, const Instruction *I,
const Value *Ptr, bool &Changed,
AccessKind AK = READ_WRITE) {
assert(isPowerOf2_32(MLK) && "Expected a single location set!");
auto *&Accesses = AccessKind2Accesses[llvm::Log2_32(MLK)];
if (!Accesses)
Accesses = new (Allocator) AccessSet();
Changed |= Accesses->insert(AccessInfo{I, Ptr, AK}).second;
State.removeAssumedBits(MLK);
}
/// Determine the underlying locations kinds for \p Ptr, e.g., globals or
/// arguments, and update the state and access map accordingly.
void categorizePtrValue(Attributor &A, const Instruction &I, const Value &Ptr,
AAMemoryLocation::StateType &State, bool &Changed);
/// Used to allocate access sets.
BumpPtrAllocator &Allocator;
/// The set of IR attributes AAMemoryLocation deals with.
static const Attribute::AttrKind AttrKinds[4];
};
const Attribute::AttrKind AAMemoryLocationImpl::AttrKinds[] = {
Attribute::ReadNone, Attribute::InaccessibleMemOnly, Attribute::ArgMemOnly,
Attribute::InaccessibleMemOrArgMemOnly};
void AAMemoryLocationImpl::categorizePtrValue(
Attributor &A, const Instruction &I, const Value &Ptr,
AAMemoryLocation::StateType &State, bool &Changed) {
LLVM_DEBUG(dbgs() << "[AAMemoryLocation] Categorize pointer locations for "
<< Ptr << " ["
<< getMemoryLocationsAsStr(State.getAssumed()) << "]\n");
auto StripGEPCB = [](Value *V) -> Value * {
auto *GEP = dyn_cast<GEPOperator>(V);
while (GEP) {
V = GEP->getPointerOperand();
GEP = dyn_cast<GEPOperator>(V);
}
return V;
};
auto VisitValueCB = [&](Value &V, const Instruction *,
AAMemoryLocation::StateType &T,
bool Stripped) -> bool {
// TODO: recognize the TBAA used for constant accesses.
MemoryLocationsKind MLK = NO_LOCATIONS;
assert(!isa<GEPOperator>(V) && "GEPs should have been stripped.");
if (isa<UndefValue>(V))
return true;
if (auto *Arg = dyn_cast<Argument>(&V)) {
if (Arg->hasByValAttr())
MLK = NO_LOCAL_MEM;
else
MLK = NO_ARGUMENT_MEM;
} else if (auto *GV = dyn_cast<GlobalValue>(&V)) {
// Reading constant memory is not treated as a read "effect" by the
// function attr pass so we won't neither. Constants defined by TBAA are
// similar. (We know we do not write it because it is constant.)
if (auto *GVar = dyn_cast<GlobalVariable>(GV))
if (GVar->isConstant())
return true;
if (GV->hasLocalLinkage())
MLK = NO_GLOBAL_INTERNAL_MEM;
else
MLK = NO_GLOBAL_EXTERNAL_MEM;
} else if (isa<ConstantPointerNull>(V) &&
!NullPointerIsDefined(getAssociatedFunction(),
V.getType()->getPointerAddressSpace())) {
return true;
} else if (isa<AllocaInst>(V)) {
MLK = NO_LOCAL_MEM;
} else if (const auto *CB = dyn_cast<CallBase>(&V)) {
const auto &NoAliasAA =
A.getAAFor<AANoAlias>(*this, IRPosition::callsite_returned(*CB));
if (NoAliasAA.isAssumedNoAlias())
MLK = NO_MALLOCED_MEM;
else
MLK = NO_UNKOWN_MEM;
} else {
MLK = NO_UNKOWN_MEM;
}
assert(MLK != NO_LOCATIONS && "No location specified!");
updateStateAndAccessesMap(T, MLK, &I, &V, Changed,
getAccessKindFromInst(&I));
LLVM_DEBUG(dbgs() << "[AAMemoryLocation] Ptr value cannot be categorized: "
<< V << " -> " << getMemoryLocationsAsStr(T.getAssumed())
<< "\n");
return true;
};
if (!genericValueTraversal<AAMemoryLocation, AAMemoryLocation::StateType>(
A, IRPosition::value(Ptr), *this, State, VisitValueCB, getCtxI(),
/* UseValueSimplify */ true,
/* MaxValues */ 32, StripGEPCB)) {
LLVM_DEBUG(
dbgs() << "[AAMemoryLocation] Pointer locations not categorized\n");
updateStateAndAccessesMap(State, NO_UNKOWN_MEM, &I, nullptr, Changed,
getAccessKindFromInst(&I));
} else {
LLVM_DEBUG(
dbgs()
<< "[AAMemoryLocation] Accessed locations with pointer locations: "
<< getMemoryLocationsAsStr(State.getAssumed()) << "\n");
}
}
void AAMemoryLocationImpl::categorizeArgumentPointerLocations(
Attributor &A, CallBase &CB, AAMemoryLocation::StateType &AccessedLocs,
bool &Changed) {
for (unsigned ArgNo = 0, E = CB.getNumArgOperands(); ArgNo < E; ++ArgNo) {
// Skip non-pointer arguments.
const Value *ArgOp = CB.getArgOperand(ArgNo);
if (!ArgOp->getType()->isPtrOrPtrVectorTy())
continue;
// Skip readnone arguments.
const IRPosition &ArgOpIRP = IRPosition::callsite_argument(CB, ArgNo);
const auto &ArgOpMemLocationAA = A.getAAFor<AAMemoryBehavior>(
*this, ArgOpIRP, /* TrackDependence */ true, DepClassTy::OPTIONAL);
if (ArgOpMemLocationAA.isAssumedReadNone())
continue;
// Categorize potentially accessed pointer arguments as if there was an
// access instruction with them as pointer.
categorizePtrValue(A, CB, *ArgOp, AccessedLocs, Changed);
}
}
AAMemoryLocation::MemoryLocationsKind
AAMemoryLocationImpl::categorizeAccessedLocations(Attributor &A, Instruction &I,
bool &Changed) {
LLVM_DEBUG(dbgs() << "[AAMemoryLocation] Categorize accessed locations for "
<< I << "\n");
AAMemoryLocation::StateType AccessedLocs;
AccessedLocs.intersectAssumedBits(NO_LOCATIONS);
if (auto *CB = dyn_cast<CallBase>(&I)) {
// First check if we assume any memory is access is visible.
const auto &CBMemLocationAA =
A.getAAFor<AAMemoryLocation>(*this, IRPosition::callsite_function(*CB));
LLVM_DEBUG(dbgs() << "[AAMemoryLocation] Categorize call site: " << I
<< " [" << CBMemLocationAA << "]\n");
if (CBMemLocationAA.isAssumedReadNone())
return NO_LOCATIONS;
if (CBMemLocationAA.isAssumedInaccessibleMemOnly()) {
updateStateAndAccessesMap(AccessedLocs, NO_INACCESSIBLE_MEM, &I, nullptr,
Changed, getAccessKindFromInst(&I));
return AccessedLocs.getAssumed();
}
uint32_t CBAssumedNotAccessedLocs =
CBMemLocationAA.getAssumedNotAccessedLocation();
// Set the argmemonly and global bit as we handle them separately below.
uint32_t CBAssumedNotAccessedLocsNoArgMem =
CBAssumedNotAccessedLocs | NO_ARGUMENT_MEM | NO_GLOBAL_MEM;
for (MemoryLocationsKind CurMLK = 1; CurMLK < NO_LOCATIONS; CurMLK *= 2) {
if (CBAssumedNotAccessedLocsNoArgMem & CurMLK)
continue;
updateStateAndAccessesMap(AccessedLocs, CurMLK, &I, nullptr, Changed,
getAccessKindFromInst(&I));
}
// Now handle global memory if it might be accessed. This is slightly tricky
// as NO_GLOBAL_MEM has multiple bits set.
bool HasGlobalAccesses = ((~CBAssumedNotAccessedLocs) & NO_GLOBAL_MEM);
if (HasGlobalAccesses) {
auto AccessPred = [&](const Instruction *, const Value *Ptr,
AccessKind Kind, MemoryLocationsKind MLK) {
updateStateAndAccessesMap(AccessedLocs, MLK, &I, Ptr, Changed,
getAccessKindFromInst(&I));
return true;
};
if (!CBMemLocationAA.checkForAllAccessesToMemoryKind(
AccessPred, inverseLocation(NO_GLOBAL_MEM, false, false)))
return AccessedLocs.getWorstState();
}
LLVM_DEBUG(
dbgs() << "[AAMemoryLocation] Accessed state before argument handling: "
<< getMemoryLocationsAsStr(AccessedLocs.getAssumed()) << "\n");
// Now handle argument memory if it might be accessed.
bool HasArgAccesses = ((~CBAssumedNotAccessedLocs) & NO_ARGUMENT_MEM);
if (HasArgAccesses)
categorizeArgumentPointerLocations(A, *CB, AccessedLocs, Changed);
LLVM_DEBUG(
dbgs() << "[AAMemoryLocation] Accessed state after argument handling: "
<< getMemoryLocationsAsStr(AccessedLocs.getAssumed()) << "\n");
return AccessedLocs.getAssumed();
}
if (const Value *Ptr = getPointerOperand(&I, /* AllowVolatile */ true)) {
LLVM_DEBUG(
dbgs() << "[AAMemoryLocation] Categorize memory access with pointer: "
<< I << " [" << *Ptr << "]\n");
categorizePtrValue(A, I, *Ptr, AccessedLocs, Changed);
return AccessedLocs.getAssumed();
}
LLVM_DEBUG(dbgs() << "[AAMemoryLocation] Failed to categorize instruction: "
<< I << "\n");
updateStateAndAccessesMap(AccessedLocs, NO_UNKOWN_MEM, &I, nullptr, Changed,
getAccessKindFromInst(&I));
return AccessedLocs.getAssumed();
}
/// An AA to represent the memory behavior function attributes.
struct AAMemoryLocationFunction final : public AAMemoryLocationImpl {
AAMemoryLocationFunction(const IRPosition &IRP, Attributor &A)
: AAMemoryLocationImpl(IRP, A) {}
/// See AbstractAttribute::updateImpl(Attributor &A).
virtual ChangeStatus updateImpl(Attributor &A) override {
const auto &MemBehaviorAA = A.getAAFor<AAMemoryBehavior>(
*this, getIRPosition(), /* TrackDependence */ false);
if (MemBehaviorAA.isAssumedReadNone()) {
if (MemBehaviorAA.isKnownReadNone())
return indicateOptimisticFixpoint();
assert(isAssumedReadNone() &&
"AAMemoryLocation was not read-none but AAMemoryBehavior was!");
A.recordDependence(MemBehaviorAA, *this, DepClassTy::OPTIONAL);
return ChangeStatus::UNCHANGED;
}
// The current assumed state used to determine a change.
auto AssumedState = getAssumed();
bool Changed = false;
auto CheckRWInst = [&](Instruction &I) {
MemoryLocationsKind MLK = categorizeAccessedLocations(A, I, Changed);
LLVM_DEBUG(dbgs() << "[AAMemoryLocation] Accessed locations for " << I
<< ": " << getMemoryLocationsAsStr(MLK) << "\n");
removeAssumedBits(inverseLocation(MLK, false, false));
// Stop once only the valid bit set in the *not assumed location*, thus
// once we don't actually exclude any memory locations in the state.
return getAssumedNotAccessedLocation() != VALID_STATE;
};
if (!A.checkForAllReadWriteInstructions(CheckRWInst, *this))
return indicatePessimisticFixpoint();
Changed |= AssumedState != getAssumed();
return Changed ? ChangeStatus::CHANGED : ChangeStatus::UNCHANGED;
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
if (isAssumedReadNone())
STATS_DECLTRACK_FN_ATTR(readnone)
else if (isAssumedArgMemOnly())
STATS_DECLTRACK_FN_ATTR(argmemonly)
else if (isAssumedInaccessibleMemOnly())
STATS_DECLTRACK_FN_ATTR(inaccessiblememonly)
else if (isAssumedInaccessibleOrArgMemOnly())
STATS_DECLTRACK_FN_ATTR(inaccessiblememorargmemonly)
}
};
/// AAMemoryLocation attribute for call sites.
struct AAMemoryLocationCallSite final : AAMemoryLocationImpl {
AAMemoryLocationCallSite(const IRPosition &IRP, Attributor &A)
: AAMemoryLocationImpl(IRP, A) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
AAMemoryLocationImpl::initialize(A);
Function *F = getAssociatedFunction();
if (!F || F->isDeclaration())
indicatePessimisticFixpoint();
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
// TODO: Once we have call site specific value information we can provide
// call site specific liveness liveness information and then it makes
// sense to specialize attributes for call sites arguments instead of
// redirecting requests to the callee argument.
Function *F = getAssociatedFunction();
const IRPosition &FnPos = IRPosition::function(*F);
auto &FnAA = A.getAAFor<AAMemoryLocation>(*this, FnPos);
bool Changed = false;
auto AccessPred = [&](const Instruction *I, const Value *Ptr,
AccessKind Kind, MemoryLocationsKind MLK) {
updateStateAndAccessesMap(getState(), MLK, I, Ptr, Changed,
getAccessKindFromInst(I));
return true;
};
if (!FnAA.checkForAllAccessesToMemoryKind(AccessPred, ALL_LOCATIONS))
return indicatePessimisticFixpoint();
return Changed ? ChangeStatus::CHANGED : ChangeStatus::UNCHANGED;
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
if (isAssumedReadNone())
STATS_DECLTRACK_CS_ATTR(readnone)
}
};
/// ------------------ Value Constant Range Attribute -------------------------
struct AAValueConstantRangeImpl : AAValueConstantRange {
using StateType = IntegerRangeState;
AAValueConstantRangeImpl(const IRPosition &IRP, Attributor &A)
: AAValueConstantRange(IRP, A) {}
/// See AbstractAttribute::getAsStr().
const std::string getAsStr() const override {
std::string Str;
llvm::raw_string_ostream OS(Str);
OS << "range(" << getBitWidth() << ")<";
getKnown().print(OS);
OS << " / ";
getAssumed().print(OS);
OS << ">";
return OS.str();
}
/// Helper function to get a SCEV expr for the associated value at program
/// point \p I.
const SCEV *getSCEV(Attributor &A, const Instruction *I = nullptr) const {
if (!getAnchorScope())
return nullptr;
ScalarEvolution *SE =
A.getInfoCache().getAnalysisResultForFunction<ScalarEvolutionAnalysis>(
*getAnchorScope());
LoopInfo *LI = A.getInfoCache().getAnalysisResultForFunction<LoopAnalysis>(
*getAnchorScope());
if (!SE || !LI)
return nullptr;
const SCEV *S = SE->getSCEV(&getAssociatedValue());
if (!I)
return S;
return SE->getSCEVAtScope(S, LI->getLoopFor(I->getParent()));
}
/// Helper function to get a range from SCEV for the associated value at
/// program point \p I.
ConstantRange getConstantRangeFromSCEV(Attributor &A,
const Instruction *I = nullptr) const {
if (!getAnchorScope())
return getWorstState(getBitWidth());
ScalarEvolution *SE =
A.getInfoCache().getAnalysisResultForFunction<ScalarEvolutionAnalysis>(
*getAnchorScope());
const SCEV *S = getSCEV(A, I);
if (!SE || !S)
return getWorstState(getBitWidth());
return SE->getUnsignedRange(S);
}
/// Helper function to get a range from LVI for the associated value at
/// program point \p I.
ConstantRange
getConstantRangeFromLVI(Attributor &A,
const Instruction *CtxI = nullptr) const {
if (!getAnchorScope())
return getWorstState(getBitWidth());
LazyValueInfo *LVI =
A.getInfoCache().getAnalysisResultForFunction<LazyValueAnalysis>(
*getAnchorScope());
if (!LVI || !CtxI)
return getWorstState(getBitWidth());
return LVI->getConstantRange(&getAssociatedValue(),
const_cast<Instruction *>(CtxI));
}
/// See AAValueConstantRange::getKnownConstantRange(..).
ConstantRange
getKnownConstantRange(Attributor &A,
const Instruction *CtxI = nullptr) const override {
if (!CtxI || CtxI == getCtxI())
return getKnown();
ConstantRange LVIR = getConstantRangeFromLVI(A, CtxI);
ConstantRange SCEVR = getConstantRangeFromSCEV(A, CtxI);
return getKnown().intersectWith(SCEVR).intersectWith(LVIR);
}
/// See AAValueConstantRange::getAssumedConstantRange(..).
ConstantRange
getAssumedConstantRange(Attributor &A,
const Instruction *CtxI = nullptr) const override {
// TODO: Make SCEV use Attributor assumption.
// We may be able to bound a variable range via assumptions in
// Attributor. ex.) If x is assumed to be in [1, 3] and y is known to
// evolve to x^2 + x, then we can say that y is in [2, 12].
if (!CtxI || CtxI == getCtxI())
return getAssumed();
ConstantRange LVIR = getConstantRangeFromLVI(A, CtxI);
ConstantRange SCEVR = getConstantRangeFromSCEV(A, CtxI);
return getAssumed().intersectWith(SCEVR).intersectWith(LVIR);
}
/// See AbstractAttribute::initialize(..).
void initialize(Attributor &A) override {
// Intersect a range given by SCEV.
intersectKnown(getConstantRangeFromSCEV(A, getCtxI()));
// Intersect a range given by LVI.
intersectKnown(getConstantRangeFromLVI(A, getCtxI()));
}
/// Helper function to create MDNode for range metadata.
static MDNode *
getMDNodeForConstantRange(Type *Ty, LLVMContext &Ctx,
const ConstantRange &AssumedConstantRange) {
Metadata *LowAndHigh[] = {ConstantAsMetadata::get(ConstantInt::get(
Ty, AssumedConstantRange.getLower())),
ConstantAsMetadata::get(ConstantInt::get(
Ty, AssumedConstantRange.getUpper()))};
return MDNode::get(Ctx, LowAndHigh);
}
/// Return true if \p Assumed is included in \p KnownRanges.
static bool isBetterRange(const ConstantRange &Assumed, MDNode *KnownRanges) {
if (Assumed.isFullSet())
return false;
if (!KnownRanges)
return true;
// If multiple ranges are annotated in IR, we give up to annotate assumed
// range for now.
// TODO: If there exists a known range which containts assumed range, we
// can say assumed range is better.
if (KnownRanges->getNumOperands() > 2)
return false;
ConstantInt *Lower =
mdconst::extract<ConstantInt>(KnownRanges->getOperand(0));
ConstantInt *Upper =
mdconst::extract<ConstantInt>(KnownRanges->getOperand(1));
ConstantRange Known(Lower->getValue(), Upper->getValue());
return Known.contains(Assumed) && Known != Assumed;
}
/// Helper function to set range metadata.
static bool
setRangeMetadataIfisBetterRange(Instruction *I,
const ConstantRange &AssumedConstantRange) {
auto *OldRangeMD = I->getMetadata(LLVMContext::MD_range);
if (isBetterRange(AssumedConstantRange, OldRangeMD)) {
if (!AssumedConstantRange.isEmptySet()) {
I->setMetadata(LLVMContext::MD_range,
getMDNodeForConstantRange(I->getType(), I->getContext(),
AssumedConstantRange));
return true;
}
}
return false;
}
/// See AbstractAttribute::manifest()
ChangeStatus manifest(Attributor &A) override {
ChangeStatus Changed = ChangeStatus::UNCHANGED;
ConstantRange AssumedConstantRange = getAssumedConstantRange(A);
assert(!AssumedConstantRange.isFullSet() && "Invalid state");
auto &V = getAssociatedValue();
if (!AssumedConstantRange.isEmptySet() &&
!AssumedConstantRange.isSingleElement()) {
if (Instruction *I = dyn_cast<Instruction>(&V)) {
assert(I == getCtxI() && "Should not annotate an instruction which is "
"not the context instruction");
if (isa<CallInst>(I) || isa<LoadInst>(I))
if (setRangeMetadataIfisBetterRange(I, AssumedConstantRange))
Changed = ChangeStatus::CHANGED;
}
}
return Changed;
}
};
struct AAValueConstantRangeArgument final
: AAArgumentFromCallSiteArguments<
AAValueConstantRange, AAValueConstantRangeImpl, IntegerRangeState> {
using Base = AAArgumentFromCallSiteArguments<
AAValueConstantRange, AAValueConstantRangeImpl, IntegerRangeState>;
AAValueConstantRangeArgument(const IRPosition &IRP, Attributor &A)
: Base(IRP, A) {}
/// See AbstractAttribute::initialize(..).
void initialize(Attributor &A) override {
if (!getAnchorScope() || getAnchorScope()->isDeclaration()) {
indicatePessimisticFixpoint();
} else {
Base::initialize(A);
}
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
STATS_DECLTRACK_ARG_ATTR(value_range)
}
};
struct AAValueConstantRangeReturned
: AAReturnedFromReturnedValues<AAValueConstantRange,
AAValueConstantRangeImpl> {
using Base = AAReturnedFromReturnedValues<AAValueConstantRange,
AAValueConstantRangeImpl>;
AAValueConstantRangeReturned(const IRPosition &IRP, Attributor &A)
: Base(IRP, A) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
STATS_DECLTRACK_FNRET_ATTR(value_range)
}
};
struct AAValueConstantRangeFloating : AAValueConstantRangeImpl {
AAValueConstantRangeFloating(const IRPosition &IRP, Attributor &A)
: AAValueConstantRangeImpl(IRP, A) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
AAValueConstantRangeImpl::initialize(A);
Value &V = getAssociatedValue();
if (auto *C = dyn_cast<ConstantInt>(&V)) {
unionAssumed(ConstantRange(C->getValue()));
indicateOptimisticFixpoint();
return;
}
if (isa<UndefValue>(&V)) {
// Collapse the undef state to 0.
unionAssumed(ConstantRange(APInt(getBitWidth(), 0)));
indicateOptimisticFixpoint();
return;
}
if (isa<CallBase>(&V))
return;
if (isa<BinaryOperator>(&V) || isa<CmpInst>(&V) || isa<CastInst>(&V))
return;
// If it is a load instruction with range metadata, use it.
if (LoadInst *LI = dyn_cast<LoadInst>(&V))
if (auto *RangeMD = LI->getMetadata(LLVMContext::MD_range)) {
intersectKnown(getConstantRangeFromMetadata(*RangeMD));
return;
}
// We can work with PHI and select instruction as we traverse their operands
// during update.
if (isa<SelectInst>(V) || isa<PHINode>(V))
return;
// Otherwise we give up.
indicatePessimisticFixpoint();
LLVM_DEBUG(dbgs() << "[AAValueConstantRange] We give up: "
<< getAssociatedValue() << "\n");
}
bool calculateBinaryOperator(
Attributor &A, BinaryOperator *BinOp, IntegerRangeState &T,
const Instruction *CtxI,
SmallVectorImpl<const AAValueConstantRange *> &QuerriedAAs) {
Value *LHS = BinOp->getOperand(0);
Value *RHS = BinOp->getOperand(1);
// TODO: Allow non integers as well.
if (!LHS->getType()->isIntegerTy() || !RHS->getType()->isIntegerTy())
return false;
auto &LHSAA =
A.getAAFor<AAValueConstantRange>(*this, IRPosition::value(*LHS));
QuerriedAAs.push_back(&LHSAA);
auto LHSAARange = LHSAA.getAssumedConstantRange(A, CtxI);
auto &RHSAA =
A.getAAFor<AAValueConstantRange>(*this, IRPosition::value(*RHS));
QuerriedAAs.push_back(&RHSAA);
auto RHSAARange = RHSAA.getAssumedConstantRange(A, CtxI);
auto AssumedRange = LHSAARange.binaryOp(BinOp->getOpcode(), RHSAARange);
T.unionAssumed(AssumedRange);
// TODO: Track a known state too.
return T.isValidState();
}
bool calculateCastInst(
Attributor &A, CastInst *CastI, IntegerRangeState &T,
const Instruction *CtxI,
SmallVectorImpl<const AAValueConstantRange *> &QuerriedAAs) {
assert(CastI->getNumOperands() == 1 && "Expected cast to be unary!");
// TODO: Allow non integers as well.
Value &OpV = *CastI->getOperand(0);
if (!OpV.getType()->isIntegerTy())
return false;
auto &OpAA =
A.getAAFor<AAValueConstantRange>(*this, IRPosition::value(OpV));
QuerriedAAs.push_back(&OpAA);
T.unionAssumed(
OpAA.getAssumed().castOp(CastI->getOpcode(), getState().getBitWidth()));
return T.isValidState();
}
bool
calculateCmpInst(Attributor &A, CmpInst *CmpI, IntegerRangeState &T,
const Instruction *CtxI,
SmallVectorImpl<const AAValueConstantRange *> &QuerriedAAs) {
Value *LHS = CmpI->getOperand(0);
Value *RHS = CmpI->getOperand(1);
// TODO: Allow non integers as well.
if (!LHS->getType()->isIntegerTy() || !RHS->getType()->isIntegerTy())
return false;
auto &LHSAA =
A.getAAFor<AAValueConstantRange>(*this, IRPosition::value(*LHS));
QuerriedAAs.push_back(&LHSAA);
auto &RHSAA =
A.getAAFor<AAValueConstantRange>(*this, IRPosition::value(*RHS));
QuerriedAAs.push_back(&RHSAA);
auto LHSAARange = LHSAA.getAssumedConstantRange(A, CtxI);
auto RHSAARange = RHSAA.getAssumedConstantRange(A, CtxI);
// If one of them is empty set, we can't decide.
if (LHSAARange.isEmptySet() || RHSAARange.isEmptySet())
return true;
bool MustTrue = false, MustFalse = false;
auto AllowedRegion =
ConstantRange::makeAllowedICmpRegion(CmpI->getPredicate(), RHSAARange);
auto SatisfyingRegion = ConstantRange::makeSatisfyingICmpRegion(
CmpI->getPredicate(), RHSAARange);
if (AllowedRegion.intersectWith(LHSAARange).isEmptySet())
MustFalse = true;
if (SatisfyingRegion.contains(LHSAARange))
MustTrue = true;
assert((!MustTrue || !MustFalse) &&
"Either MustTrue or MustFalse should be false!");
if (MustTrue)
T.unionAssumed(ConstantRange(APInt(/* numBits */ 1, /* val */ 1)));
else if (MustFalse)
T.unionAssumed(ConstantRange(APInt(/* numBits */ 1, /* val */ 0)));
else
T.unionAssumed(ConstantRange(/* BitWidth */ 1, /* isFullSet */ true));
LLVM_DEBUG(dbgs() << "[AAValueConstantRange] " << *CmpI << " " << LHSAA
<< " " << RHSAA << "\n");
// TODO: Track a known state too.
return T.isValidState();
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
auto VisitValueCB = [&](Value &V, const Instruction *CtxI,
IntegerRangeState &T, bool Stripped) -> bool {
Instruction *I = dyn_cast<Instruction>(&V);
if (!I || isa<CallBase>(I)) {
// If the value is not instruction, we query AA to Attributor.
const auto &AA =
A.getAAFor<AAValueConstantRange>(*this, IRPosition::value(V));
// Clamp operator is not used to utilize a program point CtxI.
T.unionAssumed(AA.getAssumedConstantRange(A, CtxI));
return T.isValidState();
}
SmallVector<const AAValueConstantRange *, 4> QuerriedAAs;
if (auto *BinOp = dyn_cast<BinaryOperator>(I)) {
if (!calculateBinaryOperator(A, BinOp, T, CtxI, QuerriedAAs))
return false;
} else if (auto *CmpI = dyn_cast<CmpInst>(I)) {
if (!calculateCmpInst(A, CmpI, T, CtxI, QuerriedAAs))
return false;
} else if (auto *CastI = dyn_cast<CastInst>(I)) {
if (!calculateCastInst(A, CastI, T, CtxI, QuerriedAAs))
return false;
} else {
// Give up with other instructions.
// TODO: Add other instructions
T.indicatePessimisticFixpoint();
return false;
}
// Catch circular reasoning in a pessimistic way for now.
// TODO: Check how the range evolves and if we stripped anything, see also
// AADereferenceable or AAAlign for similar situations.
for (const AAValueConstantRange *QueriedAA : QuerriedAAs) {
if (QueriedAA != this)
continue;
// If we are in a stady state we do not need to worry.
if (T.getAssumed() == getState().getAssumed())
continue;
T.indicatePessimisticFixpoint();
}
return T.isValidState();
};
IntegerRangeState T(getBitWidth());
if (!genericValueTraversal<AAValueConstantRange, IntegerRangeState>(
A, getIRPosition(), *this, T, VisitValueCB, getCtxI(),
/* UseValueSimplify */ false))
return indicatePessimisticFixpoint();
return clampStateAndIndicateChange(getState(), T);
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
STATS_DECLTRACK_FLOATING_ATTR(value_range)
}
};
struct AAValueConstantRangeFunction : AAValueConstantRangeImpl {
AAValueConstantRangeFunction(const IRPosition &IRP, Attributor &A)
: AAValueConstantRangeImpl(IRP, A) {}
/// See AbstractAttribute::initialize(...).
ChangeStatus updateImpl(Attributor &A) override {
llvm_unreachable("AAValueConstantRange(Function|CallSite)::updateImpl will "
"not be called");
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_FN_ATTR(value_range) }
};
struct AAValueConstantRangeCallSite : AAValueConstantRangeFunction {
AAValueConstantRangeCallSite(const IRPosition &IRP, Attributor &A)
: AAValueConstantRangeFunction(IRP, A) {}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_CS_ATTR(value_range) }
};
struct AAValueConstantRangeCallSiteReturned
: AACallSiteReturnedFromReturned<AAValueConstantRange,
AAValueConstantRangeImpl> {
AAValueConstantRangeCallSiteReturned(const IRPosition &IRP, Attributor &A)
: AACallSiteReturnedFromReturned<AAValueConstantRange,
AAValueConstantRangeImpl>(IRP, A) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
// If it is a load instruction with range metadata, use the metadata.
if (CallInst *CI = dyn_cast<CallInst>(&getAssociatedValue()))
if (auto *RangeMD = CI->getMetadata(LLVMContext::MD_range))
intersectKnown(getConstantRangeFromMetadata(*RangeMD));
AAValueConstantRangeImpl::initialize(A);
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
STATS_DECLTRACK_CSRET_ATTR(value_range)
}
};
struct AAValueConstantRangeCallSiteArgument : AAValueConstantRangeFloating {
AAValueConstantRangeCallSiteArgument(const IRPosition &IRP, Attributor &A)
: AAValueConstantRangeFloating(IRP, A) {}
/// See AbstractAttribute::manifest()
ChangeStatus manifest(Attributor &A) override {
return ChangeStatus::UNCHANGED;
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
STATS_DECLTRACK_CSARG_ATTR(value_range)
}
};
/// ------------------ Potential Values Attribute -------------------------
struct AAPotentialValuesImpl : AAPotentialValues {
using StateType = PotentialConstantIntValuesState;
AAPotentialValuesImpl(const IRPosition &IRP, Attributor &A)
: AAPotentialValues(IRP, A) {}
/// See AbstractAttribute::getAsStr().
const std::string getAsStr() const override {
std::string Str;
llvm::raw_string_ostream OS(Str);
OS << getState();
return OS.str();
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
return indicatePessimisticFixpoint();
}
};
struct AAPotentialValuesArgument final
: AAArgumentFromCallSiteArguments<AAPotentialValues, AAPotentialValuesImpl,
PotentialConstantIntValuesState> {
using Base =
AAArgumentFromCallSiteArguments<AAPotentialValues, AAPotentialValuesImpl,
PotentialConstantIntValuesState>;
AAPotentialValuesArgument(const IRPosition &IRP, Attributor &A)
: Base(IRP, A) {}
/// See AbstractAttribute::initialize(..).
void initialize(Attributor &A) override {
if (!getAnchorScope() || getAnchorScope()->isDeclaration()) {
indicatePessimisticFixpoint();
} else {
Base::initialize(A);
}
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
STATS_DECLTRACK_ARG_ATTR(potential_values)
}
};
struct AAPotentialValuesReturned
: AAReturnedFromReturnedValues<AAPotentialValues, AAPotentialValuesImpl> {
using Base =
AAReturnedFromReturnedValues<AAPotentialValues, AAPotentialValuesImpl>;
AAPotentialValuesReturned(const IRPosition &IRP, Attributor &A)
: Base(IRP, A) {}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
STATS_DECLTRACK_FNRET_ATTR(potential_values)
}
};
struct AAPotentialValuesFloating : AAPotentialValuesImpl {
AAPotentialValuesFloating(const IRPosition &IRP, Attributor &A)
: AAPotentialValuesImpl(IRP, A) {}
/// See AbstractAttribute::initialize(..).
void initialize(Attributor &A) override {
Value &V = getAssociatedValue();
if (auto *C = dyn_cast<ConstantInt>(&V)) {
unionAssumed(C->getValue());
indicateOptimisticFixpoint();
return;
}
if (isa<UndefValue>(&V)) {
unionAssumedWithUndef();
indicateOptimisticFixpoint();
return;
}
if (isa<BinaryOperator>(&V) || isa<ICmpInst>(&V) || isa<CastInst>(&V))
return;
if (isa<SelectInst>(V) || isa<PHINode>(V))
return;
indicatePessimisticFixpoint();
LLVM_DEBUG(dbgs() << "[AAPotentialValues] We give up: "
<< getAssociatedValue() << "\n");
}
static bool calculateICmpInst(const ICmpInst *ICI, const APInt &LHS,
const APInt &RHS) {
ICmpInst::Predicate Pred = ICI->getPredicate();
switch (Pred) {
case ICmpInst::ICMP_UGT:
return LHS.ugt(RHS);
case ICmpInst::ICMP_SGT:
return LHS.sgt(RHS);
case ICmpInst::ICMP_EQ:
return LHS.eq(RHS);
case ICmpInst::ICMP_UGE:
return LHS.uge(RHS);
case ICmpInst::ICMP_SGE:
return LHS.sge(RHS);
case ICmpInst::ICMP_ULT:
return LHS.ult(RHS);
case ICmpInst::ICMP_SLT:
return LHS.slt(RHS);
case ICmpInst::ICMP_NE:
return LHS.ne(RHS);
case ICmpInst::ICMP_ULE:
return LHS.ule(RHS);
case ICmpInst::ICMP_SLE:
return LHS.sle(RHS);
default:
llvm_unreachable("Invalid ICmp predicate!");
}
}
static APInt calculateCastInst(const CastInst *CI, const APInt &Src,
uint32_t ResultBitWidth) {
Instruction::CastOps CastOp = CI->getOpcode();
switch (CastOp) {
default:
llvm_unreachable("unsupported or not integer cast");
case Instruction::Trunc:
return Src.trunc(ResultBitWidth);
case Instruction::SExt:
return Src.sext(ResultBitWidth);
case Instruction::ZExt:
return Src.zext(ResultBitWidth);
case Instruction::BitCast:
return Src;
}
}
static APInt calculateBinaryOperator(const BinaryOperator *BinOp,
const APInt &LHS, const APInt &RHS,
bool &SkipOperation, bool &Unsupported) {
Instruction::BinaryOps BinOpcode = BinOp->getOpcode();
// Unsupported is set to true when the binary operator is not supported.
// SkipOperation is set to true when UB occur with the given operand pair
// (LHS, RHS).
// TODO: we should look at nsw and nuw keywords to handle operations
// that create poison or undef value.
switch (BinOpcode) {
default:
Unsupported = true;
return LHS;
case Instruction::Add:
return LHS + RHS;
case Instruction::Sub:
return LHS - RHS;
case Instruction::Mul:
return LHS * RHS;
case Instruction::UDiv:
if (RHS.isNullValue()) {
SkipOperation = true;
return LHS;
}
return LHS.udiv(RHS);
case Instruction::SDiv:
if (RHS.isNullValue()) {
SkipOperation = true;
return LHS;
}
return LHS.sdiv(RHS);
case Instruction::URem:
if (RHS.isNullValue()) {
SkipOperation = true;
return LHS;
}
return LHS.urem(RHS);
case Instruction::SRem:
if (RHS.isNullValue()) {
SkipOperation = true;
return LHS;
}
return LHS.srem(RHS);
case Instruction::Shl:
return LHS.shl(RHS);
case Instruction::LShr:
return LHS.lshr(RHS);
case Instruction::AShr:
return LHS.ashr(RHS);
case Instruction::And:
return LHS & RHS;
case Instruction::Or:
return LHS | RHS;
case Instruction::Xor:
return LHS ^ RHS;
}
}
bool calculateBinaryOperatorAndTakeUnion(const BinaryOperator *BinOp,
const APInt &LHS, const APInt &RHS) {
bool SkipOperation = false;
bool Unsupported = false;
APInt Result =
calculateBinaryOperator(BinOp, LHS, RHS, SkipOperation, Unsupported);
if (Unsupported)
return false;
// If SkipOperation is true, we can ignore this operand pair (L, R).
if (!SkipOperation)
unionAssumed(Result);
return isValidState();
}
ChangeStatus updateWithICmpInst(Attributor &A, ICmpInst *ICI) {
auto AssumedBefore = getAssumed();
Value *LHS = ICI->getOperand(0);
Value *RHS = ICI->getOperand(1);
if (!LHS->getType()->isIntegerTy() || !RHS->getType()->isIntegerTy())
return indicatePessimisticFixpoint();
auto &LHSAA = A.getAAFor<AAPotentialValues>(*this, IRPosition::value(*LHS));
if (!LHSAA.isValidState())
return indicatePessimisticFixpoint();
auto &RHSAA = A.getAAFor<AAPotentialValues>(*this, IRPosition::value(*RHS));
if (!RHSAA.isValidState())
return indicatePessimisticFixpoint();
const DenseSet<APInt> &LHSAAPVS = LHSAA.getAssumedSet();
const DenseSet<APInt> &RHSAAPVS = RHSAA.getAssumedSet();
// TODO: make use of undef flag to limit potential values aggressively.
bool MaybeTrue = false, MaybeFalse = false;
const APInt Zero(RHS->getType()->getIntegerBitWidth(), 0);
if (LHSAA.undefIsContained() && RHSAA.undefIsContained()) {
// The result of any comparison between undefs can be soundly replaced
// with undef.
unionAssumedWithUndef();
} else if (LHSAA.undefIsContained()) {
bool MaybeTrue = false, MaybeFalse = false;
for (const APInt &R : RHSAAPVS) {
bool CmpResult = calculateICmpInst(ICI, Zero, R);
MaybeTrue |= CmpResult;
MaybeFalse |= !CmpResult;
if (MaybeTrue & MaybeFalse)
return indicatePessimisticFixpoint();
}
} else if (RHSAA.undefIsContained()) {
for (const APInt &L : LHSAAPVS) {
bool CmpResult = calculateICmpInst(ICI, L, Zero);
MaybeTrue |= CmpResult;
MaybeFalse |= !CmpResult;
if (MaybeTrue & MaybeFalse)
return indicatePessimisticFixpoint();
}
} else {
for (const APInt &L : LHSAAPVS) {
for (const APInt &R : RHSAAPVS) {
bool CmpResult = calculateICmpInst(ICI, L, R);
MaybeTrue |= CmpResult;
MaybeFalse |= !CmpResult;
if (MaybeTrue & MaybeFalse)
return indicatePessimisticFixpoint();
}
}
}
if (MaybeTrue)
unionAssumed(APInt(/* numBits */ 1, /* val */ 1));
if (MaybeFalse)
unionAssumed(APInt(/* numBits */ 1, /* val */ 0));
return AssumedBefore == getAssumed() ? ChangeStatus::UNCHANGED
: ChangeStatus::CHANGED;
}
ChangeStatus updateWithSelectInst(Attributor &A, SelectInst *SI) {
auto AssumedBefore = getAssumed();
Value *LHS = SI->getTrueValue();
Value *RHS = SI->getFalseValue();
if (!LHS->getType()->isIntegerTy() || !RHS->getType()->isIntegerTy())
return indicatePessimisticFixpoint();
// TODO: Use assumed simplified condition value
auto &LHSAA = A.getAAFor<AAPotentialValues>(*this, IRPosition::value(*LHS));
if (!LHSAA.isValidState())
return indicatePessimisticFixpoint();
auto &RHSAA = A.getAAFor<AAPotentialValues>(*this, IRPosition::value(*RHS));
if (!RHSAA.isValidState())
return indicatePessimisticFixpoint();
if (LHSAA.undefIsContained() && RHSAA.undefIsContained())
// select i1 *, undef , undef => undef
unionAssumedWithUndef();
else {
unionAssumed(LHSAA);
unionAssumed(RHSAA);
}
return AssumedBefore == getAssumed() ? ChangeStatus::UNCHANGED
: ChangeStatus::CHANGED;
}
ChangeStatus updateWithCastInst(Attributor &A, CastInst *CI) {
auto AssumedBefore = getAssumed();
if (!CI->isIntegerCast())
return indicatePessimisticFixpoint();
assert(CI->getNumOperands() == 1 && "Expected cast to be unary!");
uint32_t ResultBitWidth = CI->getDestTy()->getIntegerBitWidth();
Value *Src = CI->getOperand(0);
auto &SrcAA = A.getAAFor<AAPotentialValues>(*this, IRPosition::value(*Src));
if (!SrcAA.isValidState())
return indicatePessimisticFixpoint();
const DenseSet<APInt> &SrcAAPVS = SrcAA.getAssumedSet();
if (SrcAA.undefIsContained())
unionAssumedWithUndef();
else {
for (const APInt &S : SrcAAPVS) {
APInt T = calculateCastInst(CI, S, ResultBitWidth);
unionAssumed(T);
}
}
return AssumedBefore == getAssumed() ? ChangeStatus::UNCHANGED
: ChangeStatus::CHANGED;
}
ChangeStatus updateWithBinaryOperator(Attributor &A, BinaryOperator *BinOp) {
auto AssumedBefore = getAssumed();
Value *LHS = BinOp->getOperand(0);
Value *RHS = BinOp->getOperand(1);
if (!LHS->getType()->isIntegerTy() || !RHS->getType()->isIntegerTy())
return indicatePessimisticFixpoint();
auto &LHSAA = A.getAAFor<AAPotentialValues>(*this, IRPosition::value(*LHS));
if (!LHSAA.isValidState())
return indicatePessimisticFixpoint();
auto &RHSAA = A.getAAFor<AAPotentialValues>(*this, IRPosition::value(*RHS));
if (!RHSAA.isValidState())
return indicatePessimisticFixpoint();
const DenseSet<APInt> &LHSAAPVS = LHSAA.getAssumedSet();
const DenseSet<APInt> &RHSAAPVS = RHSAA.getAssumedSet();
const APInt Zero = APInt(LHS->getType()->getIntegerBitWidth(), 0);
// TODO: make use of undef flag to limit potential values aggressively.
if (LHSAA.undefIsContained() && RHSAA.undefIsContained()) {
if (!calculateBinaryOperatorAndTakeUnion(BinOp, Zero, Zero))
return indicatePessimisticFixpoint();
} else if (LHSAA.undefIsContained()) {
for (const APInt &R : RHSAAPVS) {
if (!calculateBinaryOperatorAndTakeUnion(BinOp, Zero, R))
return indicatePessimisticFixpoint();
}
} else if (RHSAA.undefIsContained()) {
for (const APInt &L : LHSAAPVS) {
if (!calculateBinaryOperatorAndTakeUnion(BinOp, L, Zero))
return indicatePessimisticFixpoint();
}
} else {
for (const APInt &L : LHSAAPVS) {
for (const APInt &R : RHSAAPVS) {
if (!calculateBinaryOperatorAndTakeUnion(BinOp, L, R))
return indicatePessimisticFixpoint();
}
}
}
return AssumedBefore == getAssumed() ? ChangeStatus::UNCHANGED
: ChangeStatus::CHANGED;
}
ChangeStatus updateWithPHINode(Attributor &A, PHINode *PHI) {
auto AssumedBefore = getAssumed();
for (unsigned u = 0, e = PHI->getNumIncomingValues(); u < e; u++) {
Value *IncomingValue = PHI->getIncomingValue(u);
auto &PotentialValuesAA = A.getAAFor<AAPotentialValues>(
*this, IRPosition::value(*IncomingValue));
if (!PotentialValuesAA.isValidState())
return indicatePessimisticFixpoint();
if (PotentialValuesAA.undefIsContained())
unionAssumedWithUndef();
else
unionAssumed(PotentialValuesAA.getAssumed());
}
return AssumedBefore == getAssumed() ? ChangeStatus::UNCHANGED
: ChangeStatus::CHANGED;
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
Value &V = getAssociatedValue();
Instruction *I = dyn_cast<Instruction>(&V);
if (auto *ICI = dyn_cast<ICmpInst>(I))
return updateWithICmpInst(A, ICI);
if (auto *SI = dyn_cast<SelectInst>(I))
return updateWithSelectInst(A, SI);
if (auto *CI = dyn_cast<CastInst>(I))
return updateWithCastInst(A, CI);
if (auto *BinOp = dyn_cast<BinaryOperator>(I))
return updateWithBinaryOperator(A, BinOp);
if (auto *PHI = dyn_cast<PHINode>(I))
return updateWithPHINode(A, PHI);
return indicatePessimisticFixpoint();
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
STATS_DECLTRACK_FLOATING_ATTR(potential_values)
}
};
struct AAPotentialValuesFunction : AAPotentialValuesImpl {
AAPotentialValuesFunction(const IRPosition &IRP, Attributor &A)
: AAPotentialValuesImpl(IRP, A) {}
/// See AbstractAttribute::initialize(...).
ChangeStatus updateImpl(Attributor &A) override {
llvm_unreachable("AAPotentialValues(Function|CallSite)::updateImpl will "
"not be called");
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
STATS_DECLTRACK_FN_ATTR(potential_values)
}
};
struct AAPotentialValuesCallSite : AAPotentialValuesFunction {
AAPotentialValuesCallSite(const IRPosition &IRP, Attributor &A)
: AAPotentialValuesFunction(IRP, A) {}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
STATS_DECLTRACK_CS_ATTR(potential_values)
}
};
struct AAPotentialValuesCallSiteReturned
: AACallSiteReturnedFromReturned<AAPotentialValues, AAPotentialValuesImpl> {
AAPotentialValuesCallSiteReturned(const IRPosition &IRP, Attributor &A)
: AACallSiteReturnedFromReturned<AAPotentialValues,
AAPotentialValuesImpl>(IRP, A) {}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
STATS_DECLTRACK_CSRET_ATTR(potential_values)
}
};
struct AAPotentialValuesCallSiteArgument : AAPotentialValuesFloating {
AAPotentialValuesCallSiteArgument(const IRPosition &IRP, Attributor &A)
: AAPotentialValuesFloating(IRP, A) {}
/// See AbstractAttribute::initialize(..).
void initialize(Attributor &A) override {
Value &V = getAssociatedValue();
if (auto *C = dyn_cast<ConstantInt>(&V)) {
unionAssumed(C->getValue());
indicateOptimisticFixpoint();
return;
}
if (isa<UndefValue>(&V)) {
unionAssumedWithUndef();
indicateOptimisticFixpoint();
return;
}
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
Value &V = getAssociatedValue();
auto AssumedBefore = getAssumed();
auto &AA = A.getAAFor<AAPotentialValues>(*this, IRPosition::value(V));
const auto &S = AA.getAssumed();
unionAssumed(S);
return AssumedBefore == getAssumed() ? ChangeStatus::UNCHANGED
: ChangeStatus::CHANGED;
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
STATS_DECLTRACK_CSARG_ATTR(potential_values)
}
};
/// ------------------------ NoUndef Attribute ---------------------------------
struct AANoUndefImpl : AANoUndef {
AANoUndefImpl(const IRPosition &IRP, Attributor &A) : AANoUndef(IRP, A) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
if (getIRPosition().hasAttr({Attribute::NoUndef})) {
indicateOptimisticFixpoint();
return;
}
Value &V = getAssociatedValue();
if (isa<UndefValue>(V))
indicatePessimisticFixpoint();
else if (isa<FreezeInst>(V))
indicateOptimisticFixpoint();
else if (getPositionKind() != IRPosition::IRP_RETURNED &&
isGuaranteedNotToBeUndefOrPoison(&V))
indicateOptimisticFixpoint();
else
AANoUndef::initialize(A);
}
/// See followUsesInMBEC
bool followUseInMBEC(Attributor &A, const Use *U, const Instruction *I,
AANoUndef::StateType &State) {
const Value *UseV = U->get();
const DominatorTree *DT = nullptr;
AssumptionCache *AC = nullptr;
InformationCache &InfoCache = A.getInfoCache();
if (Function *F = getAnchorScope()) {
DT = InfoCache.getAnalysisResultForFunction<DominatorTreeAnalysis>(*F);
AC = InfoCache.getAnalysisResultForFunction<AssumptionAnalysis>(*F);
}
State.setKnown(isGuaranteedNotToBeUndefOrPoison(UseV, AC, I, DT));
bool TrackUse = false;
// Track use for instructions which must produce undef or poison bits when
// at least one operand contains such bits.
if (isa<CastInst>(*I) || isa<GetElementPtrInst>(*I))
TrackUse = true;
return TrackUse;
}
/// See AbstractAttribute::getAsStr().
const std::string getAsStr() const override {
return getAssumed() ? "noundef" : "may-undef-or-poison";
}
ChangeStatus manifest(Attributor &A) override {
// We don't manifest noundef attribute for dead positions because the
// associated values with dead positions would be replaced with undef
// values.
if (A.isAssumedDead(getIRPosition(), nullptr, nullptr))
return ChangeStatus::UNCHANGED;
// A position whose simplified value does not have any value is
// considered to be dead. We don't manifest noundef in such positions for
// the same reason above.
auto &ValueSimplifyAA = A.getAAFor<AAValueSimplify>(
*this, getIRPosition(), /* TrackDependence */ false);
if (!ValueSimplifyAA.getAssumedSimplifiedValue(A).hasValue())
return ChangeStatus::UNCHANGED;
return AANoUndef::manifest(A);
}
};
struct AANoUndefFloating : public AANoUndefImpl {
AANoUndefFloating(const IRPosition &IRP, Attributor &A)
: AANoUndefImpl(IRP, A) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
AANoUndefImpl::initialize(A);
if (!getState().isAtFixpoint())
if (Instruction *CtxI = getCtxI())
followUsesInMBEC(*this, A, getState(), *CtxI);
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
auto VisitValueCB = [&](Value &V, const Instruction *CtxI,
AANoUndef::StateType &T, bool Stripped) -> bool {
const auto &AA = A.getAAFor<AANoUndef>(*this, IRPosition::value(V));
if (!Stripped && this == &AA) {
T.indicatePessimisticFixpoint();
} else {
const AANoUndef::StateType &S =
static_cast<const AANoUndef::StateType &>(AA.getState());
T ^= S;
}
return T.isValidState();
};
StateType T;
if (!genericValueTraversal<AANoUndef, StateType>(
A, getIRPosition(), *this, T, VisitValueCB, getCtxI()))
return indicatePessimisticFixpoint();
return clampStateAndIndicateChange(getState(), T);
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_FNRET_ATTR(noundef) }
};
struct AANoUndefReturned final
: AAReturnedFromReturnedValues<AANoUndef, AANoUndefImpl> {
AANoUndefReturned(const IRPosition &IRP, Attributor &A)
: AAReturnedFromReturnedValues<AANoUndef, AANoUndefImpl>(IRP, A) {}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_FNRET_ATTR(noundef) }
};
struct AANoUndefArgument final
: AAArgumentFromCallSiteArguments<AANoUndef, AANoUndefImpl> {
AANoUndefArgument(const IRPosition &IRP, Attributor &A)
: AAArgumentFromCallSiteArguments<AANoUndef, AANoUndefImpl>(IRP, A) {}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_ARG_ATTR(noundef) }
};
struct AANoUndefCallSiteArgument final : AANoUndefFloating {
AANoUndefCallSiteArgument(const IRPosition &IRP, Attributor &A)
: AANoUndefFloating(IRP, A) {}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_CSARG_ATTR(noundef) }
};
struct AANoUndefCallSiteReturned final
: AACallSiteReturnedFromReturned<AANoUndef, AANoUndefImpl> {
AANoUndefCallSiteReturned(const IRPosition &IRP, Attributor &A)
: AACallSiteReturnedFromReturned<AANoUndef, AANoUndefImpl>(IRP, A) {}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_CSRET_ATTR(noundef) }
};
} // namespace
const char AAReturnedValues::ID = 0;
const char AANoUnwind::ID = 0;
const char AANoSync::ID = 0;
const char AANoFree::ID = 0;
const char AANonNull::ID = 0;
const char AANoRecurse::ID = 0;
const char AAWillReturn::ID = 0;
const char AAUndefinedBehavior::ID = 0;
const char AANoAlias::ID = 0;
const char AAReachability::ID = 0;
const char AANoReturn::ID = 0;
const char AAIsDead::ID = 0;
const char AADereferenceable::ID = 0;
const char AAAlign::ID = 0;
const char AANoCapture::ID = 0;
const char AAValueSimplify::ID = 0;
const char AAHeapToStack::ID = 0;
const char AAPrivatizablePtr::ID = 0;
const char AAMemoryBehavior::ID = 0;
const char AAMemoryLocation::ID = 0;
const char AAValueConstantRange::ID = 0;
const char AAPotentialValues::ID = 0;
const char AANoUndef::ID = 0;
// Macro magic to create the static generator function for attributes that
// follow the naming scheme.
#define SWITCH_PK_INV(CLASS, PK, POS_NAME) \
case IRPosition::PK: \
llvm_unreachable("Cannot create " #CLASS " for a " POS_NAME " position!");
#define SWITCH_PK_CREATE(CLASS, IRP, PK, SUFFIX) \
case IRPosition::PK: \
AA = new (A.Allocator) CLASS##SUFFIX(IRP, A); \
++NumAAs; \
break;
#define CREATE_FUNCTION_ABSTRACT_ATTRIBUTE_FOR_POSITION(CLASS) \
CLASS &CLASS::createForPosition(const IRPosition &IRP, Attributor &A) { \
CLASS *AA = nullptr; \
switch (IRP.getPositionKind()) { \
SWITCH_PK_INV(CLASS, IRP_INVALID, "invalid") \
SWITCH_PK_INV(CLASS, IRP_FLOAT, "floating") \
SWITCH_PK_INV(CLASS, IRP_ARGUMENT, "argument") \
SWITCH_PK_INV(CLASS, IRP_RETURNED, "returned") \
SWITCH_PK_INV(CLASS, IRP_CALL_SITE_RETURNED, "call site returned") \
SWITCH_PK_INV(CLASS, IRP_CALL_SITE_ARGUMENT, "call site argument") \
SWITCH_PK_CREATE(CLASS, IRP, IRP_FUNCTION, Function) \
SWITCH_PK_CREATE(CLASS, IRP, IRP_CALL_SITE, CallSite) \
} \
return *AA; \
}
#define CREATE_VALUE_ABSTRACT_ATTRIBUTE_FOR_POSITION(CLASS) \
CLASS &CLASS::createForPosition(const IRPosition &IRP, Attributor &A) { \
CLASS *AA = nullptr; \
switch (IRP.getPositionKind()) { \
SWITCH_PK_INV(CLASS, IRP_INVALID, "invalid") \
SWITCH_PK_INV(CLASS, IRP_FUNCTION, "function") \
SWITCH_PK_INV(CLASS, IRP_CALL_SITE, "call site") \
SWITCH_PK_CREATE(CLASS, IRP, IRP_FLOAT, Floating) \
SWITCH_PK_CREATE(CLASS, IRP, IRP_ARGUMENT, Argument) \
SWITCH_PK_CREATE(CLASS, IRP, IRP_RETURNED, Returned) \
SWITCH_PK_CREATE(CLASS, IRP, IRP_CALL_SITE_RETURNED, CallSiteReturned) \
SWITCH_PK_CREATE(CLASS, IRP, IRP_CALL_SITE_ARGUMENT, CallSiteArgument) \
} \
return *AA; \
}
#define CREATE_ALL_ABSTRACT_ATTRIBUTE_FOR_POSITION(CLASS) \
CLASS &CLASS::createForPosition(const IRPosition &IRP, Attributor &A) { \
CLASS *AA = nullptr; \
switch (IRP.getPositionKind()) { \
SWITCH_PK_INV(CLASS, IRP_INVALID, "invalid") \
SWITCH_PK_CREATE(CLASS, IRP, IRP_FUNCTION, Function) \
SWITCH_PK_CREATE(CLASS, IRP, IRP_CALL_SITE, CallSite) \
SWITCH_PK_CREATE(CLASS, IRP, IRP_FLOAT, Floating) \
SWITCH_PK_CREATE(CLASS, IRP, IRP_ARGUMENT, Argument) \
SWITCH_PK_CREATE(CLASS, IRP, IRP_RETURNED, Returned) \
SWITCH_PK_CREATE(CLASS, IRP, IRP_CALL_SITE_RETURNED, CallSiteReturned) \
SWITCH_PK_CREATE(CLASS, IRP, IRP_CALL_SITE_ARGUMENT, CallSiteArgument) \
} \
return *AA; \
}
#define CREATE_FUNCTION_ONLY_ABSTRACT_ATTRIBUTE_FOR_POSITION(CLASS) \
CLASS &CLASS::createForPosition(const IRPosition &IRP, Attributor &A) { \
CLASS *AA = nullptr; \
switch (IRP.getPositionKind()) { \
SWITCH_PK_INV(CLASS, IRP_INVALID, "invalid") \
SWITCH_PK_INV(CLASS, IRP_ARGUMENT, "argument") \
SWITCH_PK_INV(CLASS, IRP_FLOAT, "floating") \
SWITCH_PK_INV(CLASS, IRP_RETURNED, "returned") \
SWITCH_PK_INV(CLASS, IRP_CALL_SITE_RETURNED, "call site returned") \
SWITCH_PK_INV(CLASS, IRP_CALL_SITE_ARGUMENT, "call site argument") \
SWITCH_PK_INV(CLASS, IRP_CALL_SITE, "call site") \
SWITCH_PK_CREATE(CLASS, IRP, IRP_FUNCTION, Function) \
} \
return *AA; \
}
#define CREATE_NON_RET_ABSTRACT_ATTRIBUTE_FOR_POSITION(CLASS) \
CLASS &CLASS::createForPosition(const IRPosition &IRP, Attributor &A) { \
CLASS *AA = nullptr; \
switch (IRP.getPositionKind()) { \
SWITCH_PK_INV(CLASS, IRP_INVALID, "invalid") \
SWITCH_PK_INV(CLASS, IRP_RETURNED, "returned") \
SWITCH_PK_CREATE(CLASS, IRP, IRP_FUNCTION, Function) \
SWITCH_PK_CREATE(CLASS, IRP, IRP_CALL_SITE, CallSite) \
SWITCH_PK_CREATE(CLASS, IRP, IRP_FLOAT, Floating) \
SWITCH_PK_CREATE(CLASS, IRP, IRP_ARGUMENT, Argument) \
SWITCH_PK_CREATE(CLASS, IRP, IRP_CALL_SITE_RETURNED, CallSiteReturned) \
SWITCH_PK_CREATE(CLASS, IRP, IRP_CALL_SITE_ARGUMENT, CallSiteArgument) \
} \
return *AA; \
}
CREATE_FUNCTION_ABSTRACT_ATTRIBUTE_FOR_POSITION(AANoUnwind)
CREATE_FUNCTION_ABSTRACT_ATTRIBUTE_FOR_POSITION(AANoSync)
CREATE_FUNCTION_ABSTRACT_ATTRIBUTE_FOR_POSITION(AANoRecurse)
CREATE_FUNCTION_ABSTRACT_ATTRIBUTE_FOR_POSITION(AAWillReturn)
CREATE_FUNCTION_ABSTRACT_ATTRIBUTE_FOR_POSITION(AANoReturn)
CREATE_FUNCTION_ABSTRACT_ATTRIBUTE_FOR_POSITION(AAReturnedValues)
CREATE_FUNCTION_ABSTRACT_ATTRIBUTE_FOR_POSITION(AAMemoryLocation)
CREATE_VALUE_ABSTRACT_ATTRIBUTE_FOR_POSITION(AANonNull)
CREATE_VALUE_ABSTRACT_ATTRIBUTE_FOR_POSITION(AANoAlias)
CREATE_VALUE_ABSTRACT_ATTRIBUTE_FOR_POSITION(AAPrivatizablePtr)
CREATE_VALUE_ABSTRACT_ATTRIBUTE_FOR_POSITION(AADereferenceable)
CREATE_VALUE_ABSTRACT_ATTRIBUTE_FOR_POSITION(AAAlign)
CREATE_VALUE_ABSTRACT_ATTRIBUTE_FOR_POSITION(AANoCapture)
CREATE_VALUE_ABSTRACT_ATTRIBUTE_FOR_POSITION(AAValueConstantRange)
CREATE_VALUE_ABSTRACT_ATTRIBUTE_FOR_POSITION(AAPotentialValues)
CREATE_VALUE_ABSTRACT_ATTRIBUTE_FOR_POSITION(AANoUndef)
CREATE_ALL_ABSTRACT_ATTRIBUTE_FOR_POSITION(AAValueSimplify)
CREATE_ALL_ABSTRACT_ATTRIBUTE_FOR_POSITION(AAIsDead)
CREATE_ALL_ABSTRACT_ATTRIBUTE_FOR_POSITION(AANoFree)
CREATE_FUNCTION_ONLY_ABSTRACT_ATTRIBUTE_FOR_POSITION(AAHeapToStack)
CREATE_FUNCTION_ONLY_ABSTRACT_ATTRIBUTE_FOR_POSITION(AAReachability)
CREATE_FUNCTION_ONLY_ABSTRACT_ATTRIBUTE_FOR_POSITION(AAUndefinedBehavior)
CREATE_NON_RET_ABSTRACT_ATTRIBUTE_FOR_POSITION(AAMemoryBehavior)
#undef CREATE_FUNCTION_ONLY_ABSTRACT_ATTRIBUTE_FOR_POSITION
#undef CREATE_FUNCTION_ABSTRACT_ATTRIBUTE_FOR_POSITION
#undef CREATE_NON_RET_ABSTRACT_ATTRIBUTE_FOR_POSITION
#undef CREATE_VALUE_ABSTRACT_ATTRIBUTE_FOR_POSITION
#undef CREATE_ALL_ABSTRACT_ATTRIBUTE_FOR_POSITION
#undef SWITCH_PK_CREATE
#undef SWITCH_PK_INV