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llvm / llvm-project / llvm / 847eaac01e8d015644c082f85671fe93b9a26e24 / . / lib / Transforms / IPO / Attributor.cpp
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//===- Attributor.cpp - Module-wide attribute 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
//
//===----------------------------------------------------------------------===//
//
// This file implements an interprocedural pass that deduces and/or propagates
// attributes. This is done in an abstract interpretation style fixpoint
// iteration. 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/GraphTraits.h"
#include "llvm/ADT/PointerIntPair.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/TinyPtrVector.h"
#include "llvm/Analysis/InlineCost.h"
#include "llvm/Analysis/LazyValueInfo.h"
#include "llvm/Analysis/MemorySSAUpdater.h"
#include "llvm/Analysis/MustExecute.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/IR/Attributes.h"
#include "llvm/IR/GlobalValue.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/NoFolder.h"
#include "llvm/IR/Verifier.h"
#include "llvm/InitializePasses.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/DebugCounter.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/GraphWriter.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/Cloning.h"
#include "llvm/Transforms/Utils/Local.h"
#include <cassert>
#include <string>
using namespace llvm;
#define DEBUG_TYPE "attributor"
DEBUG_COUNTER(ManifestDBGCounter, "attributor-manifest",
"Determine what attributes are manifested in the IR");
STATISTIC(NumFnDeleted, "Number of function deleted");
STATISTIC(NumFnWithExactDefinition,
"Number of functions with exact definitions");
STATISTIC(NumFnWithoutExactDefinition,
"Number of functions without exact definitions");
STATISTIC(NumFnShallowWrappersCreated, "Number of shallow wrappers created");
STATISTIC(NumAttributesTimedOut,
"Number of abstract attributes timed out before fixpoint");
STATISTIC(NumAttributesValidFixpoint,
"Number of abstract attributes in a valid fixpoint state");
STATISTIC(NumAttributesManifested,
"Number of abstract attributes manifested in IR");
STATISTIC(NumAttributesFixedDueToRequiredDependences,
"Number of abstract attributes fixed due to required dependences");
// TODO: Determine a good default value.
//
// In the LLVM-TS and SPEC2006, 32 seems to not induce compile time overheads
// (when run with the first 5 abstract attributes). The results also indicate
// that we never reach 32 iterations but always find a fixpoint sooner.
//
// This will become more evolved once we perform two interleaved fixpoint
// iterations: bottom-up and top-down.
static cl::opt<unsigned>
MaxFixpointIterations("attributor-max-iterations", cl::Hidden,
cl::desc("Maximal number of fixpoint iterations."),
cl::init(32));
static cl::opt<unsigned, true> MaxInitializationChainLengthX(
"attributor-max-initialization-chain-length", cl::Hidden,
cl::desc(
"Maximal number of chained initializations (to avoid stack overflows)"),
cl::location(MaxInitializationChainLength), cl::init(1024));
unsigned llvm::MaxInitializationChainLength;
static cl::opt<bool> VerifyMaxFixpointIterations(
"attributor-max-iterations-verify", cl::Hidden,
cl::desc("Verify that max-iterations is a tight bound for a fixpoint"),
cl::init(false));
static cl::opt<bool> AnnotateDeclarationCallSites(
"attributor-annotate-decl-cs", cl::Hidden,
cl::desc("Annotate call sites of function declarations."), cl::init(false));
static cl::opt<bool> EnableHeapToStack("enable-heap-to-stack-conversion",
cl::init(true), cl::Hidden);
static cl::opt<bool>
AllowShallowWrappers("attributor-allow-shallow-wrappers", cl::Hidden,
cl::desc("Allow the Attributor to create shallow "
"wrappers for non-exact definitions."),
cl::init(false));
static cl::opt<bool>
AllowDeepWrapper("attributor-allow-deep-wrappers", cl::Hidden,
cl::desc("Allow the Attributor to use IP information "
"derived from non-exact functions via cloning"),
cl::init(false));
// These options can only used for debug builds.
#ifndef NDEBUG
static cl::list<std::string>
SeedAllowList("attributor-seed-allow-list", cl::Hidden,
cl::desc("Comma seperated list of attribute names that are "
"allowed to be seeded."),
cl::ZeroOrMore, cl::CommaSeparated);
static cl::list<std::string> FunctionSeedAllowList(
"attributor-function-seed-allow-list", cl::Hidden,
cl::desc("Comma seperated list of function names that are "
"allowed to be seeded."),
cl::ZeroOrMore, cl::CommaSeparated);
#endif
static cl::opt<bool>
DumpDepGraph("attributor-dump-dep-graph", cl::Hidden,
cl::desc("Dump the dependency graph to dot files."),
cl::init(false));
static cl::opt<std::string> DepGraphDotFileNamePrefix(
"attributor-depgraph-dot-filename-prefix", cl::Hidden,
cl::desc("The prefix used for the CallGraph dot file names."));
static cl::opt<bool> ViewDepGraph("attributor-view-dep-graph", cl::Hidden,
cl::desc("View the dependency graph."),
cl::init(false));
static cl::opt<bool> PrintDependencies("attributor-print-dep", cl::Hidden,
cl::desc("Print attribute dependencies"),
cl::init(false));
static cl::opt<bool> EnableCallSiteSpecific(
"attributor-enable-call-site-specific-deduction", cl::Hidden,
cl::desc("Allow the Attributor to do call site specific analysis"),
cl::init(false));
/// Logic operators for the change status enum class.
///
///{
ChangeStatus llvm::operator|(ChangeStatus L, ChangeStatus R) {
return L == ChangeStatus::CHANGED ? L : R;
}
ChangeStatus llvm::operator&(ChangeStatus L, ChangeStatus R) {
return L == ChangeStatus::UNCHANGED ? L : R;
}
///}
/// Return true if \p New is equal or worse than \p Old.
static bool isEqualOrWorse(const Attribute &New, const Attribute &Old) {
if (!Old.isIntAttribute())
return true;
return Old.getValueAsInt() >= New.getValueAsInt();
}
/// Return true if the information provided by \p Attr was added to the
/// attribute list \p Attrs. This is only the case if it was not already present
/// in \p Attrs at the position describe by \p PK and \p AttrIdx.
static bool addIfNotExistent(LLVMContext &Ctx, const Attribute &Attr,
AttributeList &Attrs, int AttrIdx) {
if (Attr.isEnumAttribute()) {
Attribute::AttrKind Kind = Attr.getKindAsEnum();
if (Attrs.hasAttribute(AttrIdx, Kind))
if (isEqualOrWorse(Attr, Attrs.getAttribute(AttrIdx, Kind)))
return false;
Attrs = Attrs.addAttribute(Ctx, AttrIdx, Attr);
return true;
}
if (Attr.isStringAttribute()) {
StringRef Kind = Attr.getKindAsString();
if (Attrs.hasAttribute(AttrIdx, Kind))
if (isEqualOrWorse(Attr, Attrs.getAttribute(AttrIdx, Kind)))
return false;
Attrs = Attrs.addAttribute(Ctx, AttrIdx, Attr);
return true;
}
if (Attr.isIntAttribute()) {
Attribute::AttrKind Kind = Attr.getKindAsEnum();
if (Attrs.hasAttribute(AttrIdx, Kind))
if (isEqualOrWorse(Attr, Attrs.getAttribute(AttrIdx, Kind)))
return false;
Attrs = Attrs.removeAttribute(Ctx, AttrIdx, Kind);
Attrs = Attrs.addAttribute(Ctx, AttrIdx, Attr);
return true;
}
llvm_unreachable("Expected enum or string attribute!");
}
Argument *IRPosition::getAssociatedArgument() const {
if (getPositionKind() == IRP_ARGUMENT)
return cast<Argument>(&getAnchorValue());
// Not an Argument and no argument number means this is not a call site
// argument, thus we cannot find a callback argument to return.
int ArgNo = getCallSiteArgNo();
if (ArgNo < 0)
return nullptr;
// Use abstract call sites to make the connection between the call site
// values and the ones in callbacks. If a callback was found that makes use
// of the underlying call site operand, we want the corresponding callback
// callee argument and not the direct callee argument.
Optional<Argument *> CBCandidateArg;
SmallVector<const Use *, 4> CallbackUses;
const auto &CB = cast<CallBase>(getAnchorValue());
AbstractCallSite::getCallbackUses(CB, CallbackUses);
for (const Use *U : CallbackUses) {
AbstractCallSite ACS(U);
assert(ACS && ACS.isCallbackCall());
if (!ACS.getCalledFunction())
continue;
for (unsigned u = 0, e = ACS.getNumArgOperands(); u < e; u++) {
// Test if the underlying call site operand is argument number u of the
// callback callee.
if (ACS.getCallArgOperandNo(u) != ArgNo)
continue;
assert(ACS.getCalledFunction()->arg_size() > u &&
"ACS mapped into var-args arguments!");
if (CBCandidateArg.hasValue()) {
CBCandidateArg = nullptr;
break;
}
CBCandidateArg = ACS.getCalledFunction()->getArg(u);
}
}
// If we found a unique callback candidate argument, return it.
if (CBCandidateArg.hasValue() && CBCandidateArg.getValue())
return CBCandidateArg.getValue();
// If no callbacks were found, or none used the underlying call site operand
// exclusively, use the direct callee argument if available.
const Function *Callee = CB.getCalledFunction();
if (Callee && Callee->arg_size() > unsigned(ArgNo))
return Callee->getArg(ArgNo);
return nullptr;
}
ChangeStatus AbstractAttribute::update(Attributor &A) {
ChangeStatus HasChanged = ChangeStatus::UNCHANGED;
if (getState().isAtFixpoint())
return HasChanged;
LLVM_DEBUG(dbgs() << "[Attributor] Update: " << *this << "\n");
HasChanged = updateImpl(A);
LLVM_DEBUG(dbgs() << "[Attributor] Update " << HasChanged << " " << *this
<< "\n");
return HasChanged;
}
ChangeStatus
IRAttributeManifest::manifestAttrs(Attributor &A, const IRPosition &IRP,
const ArrayRef<Attribute> &DeducedAttrs) {
Function *ScopeFn = IRP.getAnchorScope();
IRPosition::Kind PK = IRP.getPositionKind();
// In the following some generic code that will manifest attributes in
// DeducedAttrs if they improve the current IR. Due to the different
// annotation positions we use the underlying AttributeList interface.
AttributeList Attrs;
switch (PK) {
case IRPosition::IRP_INVALID:
case IRPosition::IRP_FLOAT:
return ChangeStatus::UNCHANGED;
case IRPosition::IRP_ARGUMENT:
case IRPosition::IRP_FUNCTION:
case IRPosition::IRP_RETURNED:
Attrs = ScopeFn->getAttributes();
break;
case IRPosition::IRP_CALL_SITE:
case IRPosition::IRP_CALL_SITE_RETURNED:
case IRPosition::IRP_CALL_SITE_ARGUMENT:
Attrs = cast<CallBase>(IRP.getAnchorValue()).getAttributes();
break;
}
ChangeStatus HasChanged = ChangeStatus::UNCHANGED;
LLVMContext &Ctx = IRP.getAnchorValue().getContext();
for (const Attribute &Attr : DeducedAttrs) {
if (!addIfNotExistent(Ctx, Attr, Attrs, IRP.getAttrIdx()))
continue;
HasChanged = ChangeStatus::CHANGED;
}
if (HasChanged == ChangeStatus::UNCHANGED)
return HasChanged;
switch (PK) {
case IRPosition::IRP_ARGUMENT:
case IRPosition::IRP_FUNCTION:
case IRPosition::IRP_RETURNED:
ScopeFn->setAttributes(Attrs);
break;
case IRPosition::IRP_CALL_SITE:
case IRPosition::IRP_CALL_SITE_RETURNED:
case IRPosition::IRP_CALL_SITE_ARGUMENT:
cast<CallBase>(IRP.getAnchorValue()).setAttributes(Attrs);
break;
case IRPosition::IRP_INVALID:
case IRPosition::IRP_FLOAT:
break;
}
return HasChanged;
}
const IRPosition IRPosition::EmptyKey(DenseMapInfo<void *>::getEmptyKey());
const IRPosition
IRPosition::TombstoneKey(DenseMapInfo<void *>::getTombstoneKey());
SubsumingPositionIterator::SubsumingPositionIterator(const IRPosition &IRP) {
IRPositions.emplace_back(IRP);
// Helper to determine if operand bundles on a call site are benin or
// potentially problematic. We handle only llvm.assume for now.
auto CanIgnoreOperandBundles = [](const CallBase &CB) {
return (isa<IntrinsicInst>(CB) &&
cast<IntrinsicInst>(CB).getIntrinsicID() == Intrinsic ::assume);
};
const auto *CB = dyn_cast<CallBase>(&IRP.getAnchorValue());
switch (IRP.getPositionKind()) {
case IRPosition::IRP_INVALID:
case IRPosition::IRP_FLOAT:
case IRPosition::IRP_FUNCTION:
return;
case IRPosition::IRP_ARGUMENT:
case IRPosition::IRP_RETURNED:
IRPositions.emplace_back(IRPosition::function(*IRP.getAnchorScope()));
return;
case IRPosition::IRP_CALL_SITE:
assert(CB && "Expected call site!");
// TODO: We need to look at the operand bundles similar to the redirection
// in CallBase.
if (!CB->hasOperandBundles() || CanIgnoreOperandBundles(*CB))
if (const Function *Callee = CB->getCalledFunction())
IRPositions.emplace_back(IRPosition::function(*Callee));
return;
case IRPosition::IRP_CALL_SITE_RETURNED:
assert(CB && "Expected call site!");
// TODO: We need to look at the operand bundles similar to the redirection
// in CallBase.
if (!CB->hasOperandBundles() || CanIgnoreOperandBundles(*CB)) {
if (const Function *Callee = CB->getCalledFunction()) {
IRPositions.emplace_back(IRPosition::returned(*Callee));
IRPositions.emplace_back(IRPosition::function(*Callee));
for (const Argument &Arg : Callee->args())
if (Arg.hasReturnedAttr()) {
IRPositions.emplace_back(
IRPosition::callsite_argument(*CB, Arg.getArgNo()));
IRPositions.emplace_back(
IRPosition::value(*CB->getArgOperand(Arg.getArgNo())));
IRPositions.emplace_back(IRPosition::argument(Arg));
}
}
}
IRPositions.emplace_back(IRPosition::callsite_function(*CB));
return;
case IRPosition::IRP_CALL_SITE_ARGUMENT: {
assert(CB && "Expected call site!");
// TODO: We need to look at the operand bundles similar to the redirection
// in CallBase.
if (!CB->hasOperandBundles() || CanIgnoreOperandBundles(*CB)) {
const Function *Callee = CB->getCalledFunction();
if (Callee) {
if (Argument *Arg = IRP.getAssociatedArgument())
IRPositions.emplace_back(IRPosition::argument(*Arg));
IRPositions.emplace_back(IRPosition::function(*Callee));
}
}
IRPositions.emplace_back(IRPosition::value(IRP.getAssociatedValue()));
return;
}
}
}
bool IRPosition::hasAttr(ArrayRef<Attribute::AttrKind> AKs,
bool IgnoreSubsumingPositions, Attributor *A) const {
SmallVector<Attribute, 4> Attrs;
for (const IRPosition &EquivIRP : SubsumingPositionIterator(*this)) {
for (Attribute::AttrKind AK : AKs)
if (EquivIRP.getAttrsFromIRAttr(AK, Attrs))
return true;
// The first position returned by the SubsumingPositionIterator is
// always the position itself. If we ignore subsuming positions we
// are done after the first iteration.
if (IgnoreSubsumingPositions)
break;
}
if (A)
for (Attribute::AttrKind AK : AKs)
if (getAttrsFromAssumes(AK, Attrs, *A))
return true;
return false;
}
void IRPosition::getAttrs(ArrayRef<Attribute::AttrKind> AKs,
SmallVectorImpl<Attribute> &Attrs,
bool IgnoreSubsumingPositions, Attributor *A) const {
for (const IRPosition &EquivIRP : SubsumingPositionIterator(*this)) {
for (Attribute::AttrKind AK : AKs)
EquivIRP.getAttrsFromIRAttr(AK, Attrs);
// The first position returned by the SubsumingPositionIterator is
// always the position itself. If we ignore subsuming positions we
// are done after the first iteration.
if (IgnoreSubsumingPositions)
break;
}
if (A)
for (Attribute::AttrKind AK : AKs)
getAttrsFromAssumes(AK, Attrs, *A);
}
bool IRPosition::getAttrsFromIRAttr(Attribute::AttrKind AK,
SmallVectorImpl<Attribute> &Attrs) const {
if (getPositionKind() == IRP_INVALID || getPositionKind() == IRP_FLOAT)
return false;
AttributeList AttrList;
if (const auto *CB = dyn_cast<CallBase>(&getAnchorValue()))
AttrList = CB->getAttributes();
else
AttrList = getAssociatedFunction()->getAttributes();
bool HasAttr = AttrList.hasAttribute(getAttrIdx(), AK);
if (HasAttr)
Attrs.push_back(AttrList.getAttribute(getAttrIdx(), AK));
return HasAttr;
}
bool IRPosition::getAttrsFromAssumes(Attribute::AttrKind AK,
SmallVectorImpl<Attribute> &Attrs,
Attributor &A) const {
assert(getPositionKind() != IRP_INVALID && "Did expect a valid position!");
Value &AssociatedValue = getAssociatedValue();
const Assume2KnowledgeMap &A2K =
A.getInfoCache().getKnowledgeMap().lookup({&AssociatedValue, AK});
// Check if we found any potential assume use, if not we don't need to create
// explorer iterators.
if (A2K.empty())
return false;
LLVMContext &Ctx = AssociatedValue.getContext();
unsigned AttrsSize = Attrs.size();
MustBeExecutedContextExplorer &Explorer =
A.getInfoCache().getMustBeExecutedContextExplorer();
auto EIt = Explorer.begin(getCtxI()), EEnd = Explorer.end(getCtxI());
for (auto &It : A2K)
if (Explorer.findInContextOf(It.first, EIt, EEnd))
Attrs.push_back(Attribute::get(Ctx, AK, It.second.Max));
return AttrsSize != Attrs.size();
}
void IRPosition::verify() {
#ifdef EXPENSIVE_CHECKS
switch (getPositionKind()) {
case IRP_INVALID:
assert((CBContext == nullptr) &&
"Invalid position must not have CallBaseContext!");
assert(!Enc.getOpaqueValue() &&
"Expected a nullptr for an invalid position!");
return;
case IRP_FLOAT:
assert((!isa<CallBase>(&getAssociatedValue()) &&
!isa<Argument>(&getAssociatedValue())) &&
"Expected specialized kind for call base and argument values!");
return;
case IRP_RETURNED:
assert(isa<Function>(getAsValuePtr()) &&
"Expected function for a 'returned' position!");
assert(getAsValuePtr() == &getAssociatedValue() &&
"Associated value mismatch!");
return;
case IRP_CALL_SITE_RETURNED:
assert((CBContext == nullptr) &&
"'call site returned' position must not have CallBaseContext!");
assert((isa<CallBase>(getAsValuePtr())) &&
"Expected call base for 'call site returned' position!");
assert(getAsValuePtr() == &getAssociatedValue() &&
"Associated value mismatch!");
return;
case IRP_CALL_SITE:
assert((CBContext == nullptr) &&
"'call site function' position must not have CallBaseContext!");
assert((isa<CallBase>(getAsValuePtr())) &&
"Expected call base for 'call site function' position!");
assert(getAsValuePtr() == &getAssociatedValue() &&
"Associated value mismatch!");
return;
case IRP_FUNCTION:
assert(isa<Function>(getAsValuePtr()) &&
"Expected function for a 'function' position!");
assert(getAsValuePtr() == &getAssociatedValue() &&
"Associated value mismatch!");
return;
case IRP_ARGUMENT:
assert(isa<Argument>(getAsValuePtr()) &&
"Expected argument for a 'argument' position!");
assert(getAsValuePtr() == &getAssociatedValue() &&
"Associated value mismatch!");
return;
case IRP_CALL_SITE_ARGUMENT: {
assert((CBContext == nullptr) &&
"'call site argument' position must not have CallBaseContext!");
Use *U = getAsUsePtr();
assert(U && "Expected use for a 'call site argument' position!");
assert(isa<CallBase>(U->getUser()) &&
"Expected call base user for a 'call site argument' position!");
assert(cast<CallBase>(U->getUser())->isArgOperand(U) &&
"Expected call base argument operand for a 'call site argument' "
"position");
assert(cast<CallBase>(U->getUser())->getArgOperandNo(U) ==
unsigned(getCallSiteArgNo()) &&
"Argument number mismatch!");
assert(U->get() == &getAssociatedValue() && "Associated value mismatch!");
return;
}
}
#endif
}
Optional<Constant *>
Attributor::getAssumedConstant(const Value &V, const AbstractAttribute &AA,
bool &UsedAssumedInformation) {
const auto &ValueSimplifyAA =
getAAFor<AAValueSimplify>(AA, IRPosition::value(V), DepClassTy::NONE);
Optional<Value *> SimplifiedV =
ValueSimplifyAA.getAssumedSimplifiedValue(*this);
bool IsKnown = ValueSimplifyAA.isKnown();
UsedAssumedInformation |= !IsKnown;
if (!SimplifiedV.hasValue()) {
recordDependence(ValueSimplifyAA, AA, DepClassTy::OPTIONAL);
return llvm::None;
}
if (isa_and_nonnull<UndefValue>(SimplifiedV.getValue())) {
recordDependence(ValueSimplifyAA, AA, DepClassTy::OPTIONAL);
return llvm::None;
}
Constant *CI = dyn_cast_or_null<Constant>(SimplifiedV.getValue());
if (CI && CI->getType() != V.getType()) {
// TODO: Check for a save conversion.
return nullptr;
}
if (CI)
recordDependence(ValueSimplifyAA, AA, DepClassTy::OPTIONAL);
return CI;
}
Attributor::~Attributor() {
// The abstract attributes are allocated via the BumpPtrAllocator Allocator,
// thus we cannot delete them. We can, and want to, destruct them though.
for (auto &DepAA : DG.SyntheticRoot.Deps) {
AbstractAttribute *AA = cast<AbstractAttribute>(DepAA.getPointer());
AA->~AbstractAttribute();
}
}
bool Attributor::isAssumedDead(const AbstractAttribute &AA,
const AAIsDead *FnLivenessAA,
bool CheckBBLivenessOnly, DepClassTy DepClass) {
const IRPosition &IRP = AA.getIRPosition();
if (!Functions.count(IRP.getAnchorScope()))
return false;
return isAssumedDead(IRP, &AA, FnLivenessAA, CheckBBLivenessOnly, DepClass);
}
bool Attributor::isAssumedDead(const Use &U,
const AbstractAttribute *QueryingAA,
const AAIsDead *FnLivenessAA,
bool CheckBBLivenessOnly, DepClassTy DepClass) {
Instruction *UserI = dyn_cast<Instruction>(U.getUser());
if (!UserI)
return isAssumedDead(IRPosition::value(*U.get()), QueryingAA, FnLivenessAA,
CheckBBLivenessOnly, DepClass);
if (auto *CB = dyn_cast<CallBase>(UserI)) {
// For call site argument uses we can check if the argument is
// unused/dead.
if (CB->isArgOperand(&U)) {
const IRPosition &CSArgPos =
IRPosition::callsite_argument(*CB, CB->getArgOperandNo(&U));
return isAssumedDead(CSArgPos, QueryingAA, FnLivenessAA,
CheckBBLivenessOnly, DepClass);
}
} else if (ReturnInst *RI = dyn_cast<ReturnInst>(UserI)) {
const IRPosition &RetPos = IRPosition::returned(*RI->getFunction());
return isAssumedDead(RetPos, QueryingAA, FnLivenessAA, CheckBBLivenessOnly,
DepClass);
} else if (PHINode *PHI = dyn_cast<PHINode>(UserI)) {
BasicBlock *IncomingBB = PHI->getIncomingBlock(U);
return isAssumedDead(*IncomingBB->getTerminator(), QueryingAA, FnLivenessAA,
CheckBBLivenessOnly, DepClass);
}
return isAssumedDead(IRPosition::value(*UserI), QueryingAA, FnLivenessAA,
CheckBBLivenessOnly, DepClass);
}
bool Attributor::isAssumedDead(const Instruction &I,
const AbstractAttribute *QueryingAA,
const AAIsDead *FnLivenessAA,
bool CheckBBLivenessOnly, DepClassTy DepClass) {
if (!FnLivenessAA)
FnLivenessAA = lookupAAFor<AAIsDead>(IRPosition::function(*I.getFunction()),
QueryingAA, DepClassTy::NONE);
// If we have a context instruction and a liveness AA we use it.
if (FnLivenessAA &&
FnLivenessAA->getIRPosition().getAnchorScope() == I.getFunction() &&
FnLivenessAA->isAssumedDead(&I)) {
if (QueryingAA)
recordDependence(*FnLivenessAA, *QueryingAA, DepClass);
return true;
}
if (CheckBBLivenessOnly)
return false;
const AAIsDead &IsDeadAA = getOrCreateAAFor<AAIsDead>(
IRPosition::value(I), QueryingAA, DepClassTy::NONE);
// Don't check liveness for AAIsDead.
if (QueryingAA == &IsDeadAA)
return false;
if (IsDeadAA.isAssumedDead()) {
if (QueryingAA)
recordDependence(IsDeadAA, *QueryingAA, DepClass);
return true;
}
return false;
}
bool Attributor::isAssumedDead(const IRPosition &IRP,
const AbstractAttribute *QueryingAA,
const AAIsDead *FnLivenessAA,
bool CheckBBLivenessOnly, DepClassTy DepClass) {
Instruction *CtxI = IRP.getCtxI();
if (CtxI &&
isAssumedDead(*CtxI, QueryingAA, FnLivenessAA,
/* CheckBBLivenessOnly */ true,
CheckBBLivenessOnly ? DepClass : DepClassTy::OPTIONAL))
return true;
if (CheckBBLivenessOnly)
return false;
// If we haven't succeeded we query the specific liveness info for the IRP.
const AAIsDead *IsDeadAA;
if (IRP.getPositionKind() == IRPosition::IRP_CALL_SITE)
IsDeadAA = &getOrCreateAAFor<AAIsDead>(
IRPosition::callsite_returned(cast<CallBase>(IRP.getAssociatedValue())),
QueryingAA, DepClassTy::NONE);
else
IsDeadAA = &getOrCreateAAFor<AAIsDead>(IRP, QueryingAA, DepClassTy::NONE);
// Don't check liveness for AAIsDead.
if (QueryingAA == IsDeadAA)
return false;
if (IsDeadAA->isAssumedDead()) {
if (QueryingAA)
recordDependence(*IsDeadAA, *QueryingAA, DepClass);
return true;
}
return false;
}
bool Attributor::checkForAllUses(function_ref<bool(const Use &, bool &)> Pred,
const AbstractAttribute &QueryingAA,
const Value &V, DepClassTy LivenessDepClass) {
// Check the trivial case first as it catches void values.
if (V.use_empty())
return true;
// If the value is replaced by another one, for now a constant, we do not have
// uses. Note that this requires users of `checkForAllUses` to not recurse but
// instead use the `follow` callback argument to look at transitive users,
// however, that should be clear from the presence of the argument.
bool UsedAssumedInformation = false;
Optional<Constant *> C =
getAssumedConstant(V, QueryingAA, UsedAssumedInformation);
if (C.hasValue() && C.getValue()) {
LLVM_DEBUG(dbgs() << "[Attributor] Value is simplified, uses skipped: " << V
<< " -> " << *C.getValue() << "\n");
return true;
}
const IRPosition &IRP = QueryingAA.getIRPosition();
SmallVector<const Use *, 16> Worklist;
SmallPtrSet<const Use *, 16> Visited;
for (const Use &U : V.uses())
Worklist.push_back(&U);
LLVM_DEBUG(dbgs() << "[Attributor] Got " << Worklist.size()
<< " initial uses to check\n");
const Function *ScopeFn = IRP.getAnchorScope();
const auto *LivenessAA =
ScopeFn ? &getAAFor<AAIsDead>(QueryingAA, IRPosition::function(*ScopeFn),
DepClassTy::NONE)
: nullptr;
while (!Worklist.empty()) {
const Use *U = Worklist.pop_back_val();
if (!Visited.insert(U).second)
continue;
LLVM_DEBUG(dbgs() << "[Attributor] Check use: " << **U << " in "
<< *U->getUser() << "\n");
if (isAssumedDead(*U, &QueryingAA, LivenessAA,
/* CheckBBLivenessOnly */ false, LivenessDepClass)) {
LLVM_DEBUG(dbgs() << "[Attributor] Dead use, skip!\n");
continue;
}
if (U->getUser()->isDroppable()) {
LLVM_DEBUG(dbgs() << "[Attributor] Droppable user, skip!\n");
continue;
}
bool Follow = false;
if (!Pred(*U, Follow))
return false;
if (!Follow)
continue;
for (const Use &UU : U->getUser()->uses())
Worklist.push_back(&UU);
}
return true;
}
bool Attributor::checkForAllCallSites(function_ref<bool(AbstractCallSite)> Pred,
const AbstractAttribute &QueryingAA,
bool RequireAllCallSites,
bool &AllCallSitesKnown) {
// We can try to determine information from
// the call sites. However, this is only possible all call sites are known,
// hence the function has internal linkage.
const IRPosition &IRP = QueryingAA.getIRPosition();
const Function *AssociatedFunction = IRP.getAssociatedFunction();
if (!AssociatedFunction) {
LLVM_DEBUG(dbgs() << "[Attributor] No function associated with " << IRP
<< "\n");
AllCallSitesKnown = false;
return false;
}
return checkForAllCallSites(Pred, *AssociatedFunction, RequireAllCallSites,
&QueryingAA, AllCallSitesKnown);
}
bool Attributor::checkForAllCallSites(function_ref<bool(AbstractCallSite)> Pred,
const Function &Fn,
bool RequireAllCallSites,
const AbstractAttribute *QueryingAA,
bool &AllCallSitesKnown) {
if (RequireAllCallSites && !Fn.hasLocalLinkage()) {
LLVM_DEBUG(
dbgs()
<< "[Attributor] Function " << Fn.getName()
<< " has no internal linkage, hence not all call sites are known\n");
AllCallSitesKnown = false;
return false;
}
// If we do not require all call sites we might not see all.
AllCallSitesKnown = RequireAllCallSites;
SmallVector<const Use *, 8> Uses(make_pointer_range(Fn.uses()));
for (unsigned u = 0; u < Uses.size(); ++u) {
const Use &U = *Uses[u];
LLVM_DEBUG(dbgs() << "[Attributor] Check use: " << *U << " in "
<< *U.getUser() << "\n");
if (isAssumedDead(U, QueryingAA, nullptr, /* CheckBBLivenessOnly */ true)) {
LLVM_DEBUG(dbgs() << "[Attributor] Dead use, skip!\n");
continue;
}
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(U.getUser())) {
if (CE->isCast() && CE->getType()->isPointerTy() &&
CE->getType()->getPointerElementType()->isFunctionTy()) {
for (const Use &CEU : CE->uses())
Uses.push_back(&CEU);
continue;
}
}
AbstractCallSite ACS(&U);
if (!ACS) {
LLVM_DEBUG(dbgs() << "[Attributor] Function " << Fn.getName()
<< " has non call site use " << *U.get() << " in "
<< *U.getUser() << "\n");
// BlockAddress users are allowed.
if (isa<BlockAddress>(U.getUser()))
continue;
return false;
}
const Use *EffectiveUse =
ACS.isCallbackCall() ? &ACS.getCalleeUseForCallback() : &U;
if (!ACS.isCallee(EffectiveUse)) {
if (!RequireAllCallSites)
continue;
LLVM_DEBUG(dbgs() << "[Attributor] User " << EffectiveUse->getUser()
<< " is an invalid use of " << Fn.getName() << "\n");
return false;
}
// Make sure the arguments that can be matched between the call site and the
// callee argee on their type. It is unlikely they do not and it doesn't
// make sense for all attributes to know/care about this.
assert(&Fn == ACS.getCalledFunction() && "Expected known callee");
unsigned MinArgsParams =
std::min(size_t(ACS.getNumArgOperands()), Fn.arg_size());
for (unsigned u = 0; u < MinArgsParams; ++u) {
Value *CSArgOp = ACS.getCallArgOperand(u);
if (CSArgOp && Fn.getArg(u)->getType() != CSArgOp->getType()) {
LLVM_DEBUG(
dbgs() << "[Attributor] Call site / callee argument type mismatch ["
<< u << "@" << Fn.getName() << ": "
<< *Fn.getArg(u)->getType() << " vs. "
<< *ACS.getCallArgOperand(u)->getType() << "\n");
return false;
}
}
if (Pred(ACS))
continue;
LLVM_DEBUG(dbgs() << "[Attributor] Call site callback failed for "
<< *ACS.getInstruction() << "\n");
return false;
}
return true;
}
bool Attributor::shouldPropagateCallBaseContext(const IRPosition &IRP) {
// TODO: Maintain a cache of Values that are
// on the pathway from a Argument to a Instruction that would effect the
// liveness/return state etc.
return EnableCallSiteSpecific;
}
bool Attributor::checkForAllReturnedValuesAndReturnInsts(
function_ref<bool(Value &, const SmallSetVector<ReturnInst *, 4> &)> Pred,
const AbstractAttribute &QueryingAA) {
const IRPosition &IRP = QueryingAA.getIRPosition();
// Since we need to provide return instructions we have to have an exact
// definition.
const Function *AssociatedFunction = IRP.getAssociatedFunction();
if (!AssociatedFunction)
return false;
// If this is a call site query we use the call site specific return values
// and liveness information.
// TODO: use the function scope once we have call site AAReturnedValues.
const IRPosition &QueryIRP = IRPosition::function(*AssociatedFunction);
const auto &AARetVal =
getAAFor<AAReturnedValues>(QueryingAA, QueryIRP, DepClassTy::REQUIRED);
if (!AARetVal.getState().isValidState())
return false;
return AARetVal.checkForAllReturnedValuesAndReturnInsts(Pred);
}
bool Attributor::checkForAllReturnedValues(
function_ref<bool(Value &)> Pred, const AbstractAttribute &QueryingAA) {
const IRPosition &IRP = QueryingAA.getIRPosition();
const Function *AssociatedFunction = IRP.getAssociatedFunction();
if (!AssociatedFunction)
return false;
// TODO: use the function scope once we have call site AAReturnedValues.
const IRPosition &QueryIRP = IRPosition::function(*AssociatedFunction);
const auto &AARetVal =
getAAFor<AAReturnedValues>(QueryingAA, QueryIRP, DepClassTy::REQUIRED);
if (!AARetVal.getState().isValidState())
return false;
return AARetVal.checkForAllReturnedValuesAndReturnInsts(
[&](Value &RV, const SmallSetVector<ReturnInst *, 4> &) {
return Pred(RV);
});
}
static bool checkForAllInstructionsImpl(
Attributor *A, InformationCache::OpcodeInstMapTy &OpcodeInstMap,
function_ref<bool(Instruction &)> Pred, const AbstractAttribute *QueryingAA,
const AAIsDead *LivenessAA, const ArrayRef<unsigned> &Opcodes,
bool CheckBBLivenessOnly = false) {
for (unsigned Opcode : Opcodes) {
// Check if we have instructions with this opcode at all first.
auto *Insts = OpcodeInstMap.lookup(Opcode);
if (!Insts)
continue;
for (Instruction *I : *Insts) {
// Skip dead instructions.
if (A && A->isAssumedDead(IRPosition::value(*I), QueryingAA, LivenessAA,
CheckBBLivenessOnly))
continue;
if (!Pred(*I))
return false;
}
}
return true;
}
bool Attributor::checkForAllInstructions(function_ref<bool(Instruction &)> Pred,
const AbstractAttribute &QueryingAA,
const ArrayRef<unsigned> &Opcodes,
bool CheckBBLivenessOnly) {
const IRPosition &IRP = QueryingAA.getIRPosition();
// Since we need to provide instructions we have to have an exact definition.
const Function *AssociatedFunction = IRP.getAssociatedFunction();
if (!AssociatedFunction)
return false;
// TODO: use the function scope once we have call site AAReturnedValues.
const IRPosition &QueryIRP = IRPosition::function(*AssociatedFunction);
const auto *LivenessAA =
CheckBBLivenessOnly
? nullptr
: &(getAAFor<AAIsDead>(QueryingAA, QueryIRP, DepClassTy::NONE));
auto &OpcodeInstMap =
InfoCache.getOpcodeInstMapForFunction(*AssociatedFunction);
if (!checkForAllInstructionsImpl(this, OpcodeInstMap, Pred, &QueryingAA,
LivenessAA, Opcodes, CheckBBLivenessOnly))
return false;
return true;
}
bool Attributor::checkForAllReadWriteInstructions(
function_ref<bool(Instruction &)> Pred, AbstractAttribute &QueryingAA) {
const Function *AssociatedFunction =
QueryingAA.getIRPosition().getAssociatedFunction();
if (!AssociatedFunction)
return false;
// TODO: use the function scope once we have call site AAReturnedValues.
const IRPosition &QueryIRP = IRPosition::function(*AssociatedFunction);
const auto &LivenessAA =
getAAFor<AAIsDead>(QueryingAA, QueryIRP, DepClassTy::NONE);
for (Instruction *I :
InfoCache.getReadOrWriteInstsForFunction(*AssociatedFunction)) {
// Skip dead instructions.
if (isAssumedDead(IRPosition::value(*I), &QueryingAA, &LivenessAA))
continue;
if (!Pred(*I))
return false;
}
return true;
}
void Attributor::runTillFixpoint() {
TimeTraceScope TimeScope("Attributor::runTillFixpoint");
LLVM_DEBUG(dbgs() << "[Attributor] Identified and initialized "
<< DG.SyntheticRoot.Deps.size()
<< " abstract attributes.\n");
// Now that all abstract attributes are collected and initialized we start
// the abstract analysis.
unsigned IterationCounter = 1;
SmallVector<AbstractAttribute *, 32> ChangedAAs;
SetVector<AbstractAttribute *> Worklist, InvalidAAs;
Worklist.insert(DG.SyntheticRoot.begin(), DG.SyntheticRoot.end());
do {
// Remember the size to determine new attributes.
size_t NumAAs = DG.SyntheticRoot.Deps.size();
LLVM_DEBUG(dbgs() << "\n\n[Attributor] #Iteration: " << IterationCounter
<< ", Worklist size: " << Worklist.size() << "\n");
// For invalid AAs we can fix dependent AAs that have a required dependence,
// thereby folding long dependence chains in a single step without the need
// to run updates.
for (unsigned u = 0; u < InvalidAAs.size(); ++u) {
AbstractAttribute *InvalidAA = InvalidAAs[u];
// Check the dependences to fast track invalidation.
LLVM_DEBUG(dbgs() << "[Attributor] InvalidAA: " << *InvalidAA << " has "
<< InvalidAA->Deps.size()
<< " required & optional dependences\n");
while (!InvalidAA->Deps.empty()) {
const auto &Dep = InvalidAA->Deps.back();
InvalidAA->Deps.pop_back();
AbstractAttribute *DepAA = cast<AbstractAttribute>(Dep.getPointer());
if (Dep.getInt() == unsigned(DepClassTy::OPTIONAL)) {
Worklist.insert(DepAA);
continue;
}
DepAA->getState().indicatePessimisticFixpoint();
assert(DepAA->getState().isAtFixpoint() && "Expected fixpoint state!");
if (!DepAA->getState().isValidState())
InvalidAAs.insert(DepAA);
else
ChangedAAs.push_back(DepAA);
}
}
// Add all abstract attributes that are potentially dependent on one that
// changed to the work list.
for (AbstractAttribute *ChangedAA : ChangedAAs)
while (!ChangedAA->Deps.empty()) {
Worklist.insert(
cast<AbstractAttribute>(ChangedAA->Deps.back().getPointer()));
ChangedAA->Deps.pop_back();
}
LLVM_DEBUG(dbgs() << "[Attributor] #Iteration: " << IterationCounter
<< ", Worklist+Dependent size: " << Worklist.size()
<< "\n");
// Reset the changed and invalid set.
ChangedAAs.clear();
InvalidAAs.clear();
// Update all abstract attribute in the work list and record the ones that
// changed.
for (AbstractAttribute *AA : Worklist) {
const auto &AAState = AA->getState();
if (!AAState.isAtFixpoint())
if (updateAA(*AA) == ChangeStatus::CHANGED)
ChangedAAs.push_back(AA);
// Use the InvalidAAs vector to propagate invalid states fast transitively
// without requiring updates.
if (!AAState.isValidState())
InvalidAAs.insert(AA);
}
// Add attributes to the changed set if they have been created in the last
// iteration.
ChangedAAs.append(DG.SyntheticRoot.begin() + NumAAs,
DG.SyntheticRoot.end());
// Reset the work list and repopulate with the changed abstract attributes.
// Note that dependent ones are added above.
Worklist.clear();
Worklist.insert(ChangedAAs.begin(), ChangedAAs.end());
} while (!Worklist.empty() && (IterationCounter++ < MaxFixpointIterations ||
VerifyMaxFixpointIterations));
LLVM_DEBUG(dbgs() << "\n[Attributor] Fixpoint iteration done after: "
<< IterationCounter << "/" << MaxFixpointIterations
<< " iterations\n");
// Reset abstract arguments not settled in a sound fixpoint by now. This
// happens when we stopped the fixpoint iteration early. Note that only the
// ones marked as "changed" *and* the ones transitively depending on them
// need to be reverted to a pessimistic state. Others might not be in a
// fixpoint state but we can use the optimistic results for them anyway.
SmallPtrSet<AbstractAttribute *, 32> Visited;
for (unsigned u = 0; u < ChangedAAs.size(); u++) {
AbstractAttribute *ChangedAA = ChangedAAs[u];
if (!Visited.insert(ChangedAA).second)
continue;
AbstractState &State = ChangedAA->getState();
if (!State.isAtFixpoint()) {
State.indicatePessimisticFixpoint();
NumAttributesTimedOut++;
}
while (!ChangedAA->Deps.empty()) {
ChangedAAs.push_back(
cast<AbstractAttribute>(ChangedAA->Deps.back().getPointer()));
ChangedAA->Deps.pop_back();
}
}
LLVM_DEBUG({
if (!Visited.empty())
dbgs() << "\n[Attributor] Finalized " << Visited.size()
<< " abstract attributes.\n";
});
if (VerifyMaxFixpointIterations &&
IterationCounter != MaxFixpointIterations) {
errs() << "\n[Attributor] Fixpoint iteration done after: "
<< IterationCounter << "/" << MaxFixpointIterations
<< " iterations\n";
llvm_unreachable("The fixpoint was not reached with exactly the number of "
"specified iterations!");
}
}
ChangeStatus Attributor::manifestAttributes() {
TimeTraceScope TimeScope("Attributor::manifestAttributes");
size_t NumFinalAAs = DG.SyntheticRoot.Deps.size();
unsigned NumManifested = 0;
unsigned NumAtFixpoint = 0;
ChangeStatus ManifestChange = ChangeStatus::UNCHANGED;
for (auto &DepAA : DG.SyntheticRoot.Deps) {
AbstractAttribute *AA = cast<AbstractAttribute>(DepAA.getPointer());
AbstractState &State = AA->getState();
// If there is not already a fixpoint reached, we can now take the
// optimistic state. This is correct because we enforced a pessimistic one
// on abstract attributes that were transitively dependent on a changed one
// already above.
if (!State.isAtFixpoint())
State.indicateOptimisticFixpoint();
// We must not manifest Attributes that use Callbase info.
if (AA->hasCallBaseContext())
continue;
// If the state is invalid, we do not try to manifest it.
if (!State.isValidState())
continue;
// Skip dead code.
if (isAssumedDead(*AA, nullptr, /* CheckBBLivenessOnly */ true))
continue;
// Check if the manifest debug counter that allows skipping manifestation of
// AAs
if (!DebugCounter::shouldExecute(ManifestDBGCounter))
continue;
// Manifest the state and record if we changed the IR.
ChangeStatus LocalChange = AA->manifest(*this);
if (LocalChange == ChangeStatus::CHANGED && AreStatisticsEnabled())
AA->trackStatistics();
LLVM_DEBUG(dbgs() << "[Attributor] Manifest " << LocalChange << " : " << *AA
<< "\n");
ManifestChange = ManifestChange | LocalChange;
NumAtFixpoint++;
NumManifested += (LocalChange == ChangeStatus::CHANGED);
}
(void)NumManifested;
(void)NumAtFixpoint;
LLVM_DEBUG(dbgs() << "\n[Attributor] Manifested " << NumManifested
<< " arguments while " << NumAtFixpoint
<< " were in a valid fixpoint state\n");
NumAttributesManifested += NumManifested;
NumAttributesValidFixpoint += NumAtFixpoint;
(void)NumFinalAAs;
if (NumFinalAAs != DG.SyntheticRoot.Deps.size()) {
for (unsigned u = NumFinalAAs; u < DG.SyntheticRoot.Deps.size(); ++u)
errs() << "Unexpected abstract attribute: "
<< cast<AbstractAttribute>(DG.SyntheticRoot.Deps[u].getPointer())
<< " :: "
<< cast<AbstractAttribute>(DG.SyntheticRoot.Deps[u].getPointer())
->getIRPosition()
.getAssociatedValue()
<< "\n";
llvm_unreachable("Expected the final number of abstract attributes to "
"remain unchanged!");
}
return ManifestChange;
}
void Attributor::identifyDeadInternalFunctions() {
// Early exit if we don't intend to delete functions.
if (!DeleteFns)
return;
// Identify dead internal functions and delete them. This happens outside
// the other fixpoint analysis as we might treat potentially dead functions
// as live to lower the number of iterations. If they happen to be dead, the
// below fixpoint loop will identify and eliminate them.
SmallVector<Function *, 8> InternalFns;
for (Function *F : Functions)
if (F->hasLocalLinkage())
InternalFns.push_back(F);
SmallPtrSet<Function *, 8> LiveInternalFns;
bool FoundLiveInternal = true;
while (FoundLiveInternal) {
FoundLiveInternal = false;
for (unsigned u = 0, e = InternalFns.size(); u < e; ++u) {
Function *F = InternalFns[u];
if (!F)
continue;
bool AllCallSitesKnown;
if (checkForAllCallSites(
[&](AbstractCallSite ACS) {
Function *Callee = ACS.getInstruction()->getFunction();
return ToBeDeletedFunctions.count(Callee) ||
(Functions.count(Callee) && Callee->hasLocalLinkage() &&
!LiveInternalFns.count(Callee));
},
*F, true, nullptr, AllCallSitesKnown)) {
continue;
}
LiveInternalFns.insert(F);
InternalFns[u] = nullptr;
FoundLiveInternal = true;
}
}
for (unsigned u = 0, e = InternalFns.size(); u < e; ++u)
if (Function *F = InternalFns[u])
ToBeDeletedFunctions.insert(F);
}
ChangeStatus Attributor::cleanupIR() {
TimeTraceScope TimeScope("Attributor::cleanupIR");
// Delete stuff at the end to avoid invalid references and a nice order.
LLVM_DEBUG(dbgs() << "\n[Attributor] Delete at least "
<< ToBeDeletedFunctions.size() << " functions and "
<< ToBeDeletedBlocks.size() << " blocks and "
<< ToBeDeletedInsts.size() << " instructions and "
<< ToBeChangedUses.size() << " uses\n");
SmallVector<WeakTrackingVH, 32> DeadInsts;
SmallVector<Instruction *, 32> TerminatorsToFold;
for (auto &It : ToBeChangedUses) {
Use *U = It.first;
Value *NewV = It.second;
Value *OldV = U->get();
// Do not replace uses in returns if the value is a must-tail call we will
// not delete.
if (isa<ReturnInst>(U->getUser()))
if (auto *CI = dyn_cast<CallInst>(OldV->stripPointerCasts()))
if (CI->isMustTailCall() && !ToBeDeletedInsts.count(CI))
continue;
LLVM_DEBUG(dbgs() << "Use " << *NewV << " in " << *U->getUser()
<< " instead of " << *OldV << "\n");
U->set(NewV);
// Do not modify call instructions outside the SCC.
if (auto *CB = dyn_cast<CallBase>(OldV))
if (!Functions.count(CB->getCaller()))
continue;
if (Instruction *I = dyn_cast<Instruction>(OldV)) {
CGModifiedFunctions.insert(I->getFunction());
if (!isa<PHINode>(I) && !ToBeDeletedInsts.count(I) &&
isInstructionTriviallyDead(I))
DeadInsts.push_back(I);
}
if (isa<UndefValue>(NewV) && isa<CallBase>(U->getUser())) {
auto *CB = cast<CallBase>(U->getUser());
if (CB->isArgOperand(U)) {
unsigned Idx = CB->getArgOperandNo(U);
CB->removeParamAttr(Idx, Attribute::NoUndef);
Function *Fn = CB->getCalledFunction();
assert(Fn && "Expected callee when call argument is replaced!");
if (Fn->arg_size() > Idx)
Fn->removeParamAttr(Idx, Attribute::NoUndef);
}
}
if (isa<Constant>(NewV) && isa<BranchInst>(U->getUser())) {
Instruction *UserI = cast<Instruction>(U->getUser());
if (isa<UndefValue>(NewV)) {
ToBeChangedToUnreachableInsts.insert(UserI);
} else {
TerminatorsToFold.push_back(UserI);
}
}
}
for (auto &V : InvokeWithDeadSuccessor)
if (InvokeInst *II = dyn_cast_or_null<InvokeInst>(V)) {
bool UnwindBBIsDead = II->hasFnAttr(Attribute::NoUnwind);
bool NormalBBIsDead = II->hasFnAttr(Attribute::NoReturn);
bool Invoke2CallAllowed =
!AAIsDead::mayCatchAsynchronousExceptions(*II->getFunction());
assert((UnwindBBIsDead || NormalBBIsDead) &&
"Invoke does not have dead successors!");
BasicBlock *BB = II->getParent();
BasicBlock *NormalDestBB = II->getNormalDest();
if (UnwindBBIsDead) {
Instruction *NormalNextIP = &NormalDestBB->front();
if (Invoke2CallAllowed) {
changeToCall(II);
NormalNextIP = BB->getTerminator();
}
if (NormalBBIsDead)
ToBeChangedToUnreachableInsts.insert(NormalNextIP);
} else {
assert(NormalBBIsDead && "Broken invariant!");
if (!NormalDestBB->getUniquePredecessor())
NormalDestBB = SplitBlockPredecessors(NormalDestBB, {BB}, ".dead");
ToBeChangedToUnreachableInsts.insert(&NormalDestBB->front());
}
}
for (Instruction *I : TerminatorsToFold) {
CGModifiedFunctions.insert(I->getFunction());
ConstantFoldTerminator(I->getParent());
}
for (auto &V : ToBeChangedToUnreachableInsts)
if (Instruction *I = dyn_cast_or_null<Instruction>(V)) {
CGModifiedFunctions.insert(I->getFunction());
changeToUnreachable(I, /* UseLLVMTrap */ false);
}
for (auto &V : ToBeDeletedInsts) {
if (Instruction *I = dyn_cast_or_null<Instruction>(V)) {
I->dropDroppableUses();
CGModifiedFunctions.insert(I->getFunction());
if (!I->getType()->isVoidTy())
I->replaceAllUsesWith(UndefValue::get(I->getType()));
if (!isa<PHINode>(I) && isInstructionTriviallyDead(I))
DeadInsts.push_back(I);
else
I->eraseFromParent();
}
}
LLVM_DEBUG(dbgs() << "[Attributor] DeadInsts size: " << DeadInsts.size()
<< "\n");
RecursivelyDeleteTriviallyDeadInstructions(DeadInsts);
if (unsigned NumDeadBlocks = ToBeDeletedBlocks.size()) {
SmallVector<BasicBlock *, 8> ToBeDeletedBBs;
ToBeDeletedBBs.reserve(NumDeadBlocks);
for (BasicBlock *BB : ToBeDeletedBlocks) {
CGModifiedFunctions.insert(BB->getParent());
ToBeDeletedBBs.push_back(BB);
}
// Actually we do not delete the blocks but squash them into a single
// unreachable but untangling branches that jump here is something we need
// to do in a more generic way.
DetatchDeadBlocks(ToBeDeletedBBs, nullptr);
}
identifyDeadInternalFunctions();
// Rewrite the functions as requested during manifest.
ChangeStatus ManifestChange = rewriteFunctionSignatures(CGModifiedFunctions);
for (Function *Fn : CGModifiedFunctions)
if (!ToBeDeletedFunctions.count(Fn))
CGUpdater.reanalyzeFunction(*Fn);
for (Function *Fn : ToBeDeletedFunctions) {
if (!Functions.count(Fn))
continue;
CGUpdater.removeFunction(*Fn);
}
if (!ToBeChangedUses.empty())
ManifestChange = ChangeStatus::CHANGED;
if (!ToBeChangedToUnreachableInsts.empty())
ManifestChange = ChangeStatus::CHANGED;
if (!ToBeDeletedFunctions.empty())
ManifestChange = ChangeStatus::CHANGED;
if (!ToBeDeletedBlocks.empty())
ManifestChange = ChangeStatus::CHANGED;
if (!ToBeDeletedInsts.empty())
ManifestChange = ChangeStatus::CHANGED;
if (!InvokeWithDeadSuccessor.empty())
ManifestChange = ChangeStatus::CHANGED;
if (!DeadInsts.empty())
ManifestChange = ChangeStatus::CHANGED;
NumFnDeleted += ToBeDeletedFunctions.size();
LLVM_DEBUG(dbgs() << "[Attributor] Deleted " << ToBeDeletedFunctions.size()
<< " functions after manifest.\n");
#ifdef EXPENSIVE_CHECKS
for (Function *F : Functions) {
if (ToBeDeletedFunctions.count(F))
continue;
assert(!verifyFunction(*F, &errs()) && "Module verification failed!");
}
#endif
return ManifestChange;
}
ChangeStatus Attributor::run() {
TimeTraceScope TimeScope("Attributor::run");
Phase = AttributorPhase::UPDATE;
runTillFixpoint();
// dump graphs on demand
if (DumpDepGraph)
DG.dumpGraph();
if (ViewDepGraph)
DG.viewGraph();
if (PrintDependencies)
DG.print();
Phase = AttributorPhase::MANIFEST;
ChangeStatus ManifestChange = manifestAttributes();
Phase = AttributorPhase::CLEANUP;
ChangeStatus CleanupChange = cleanupIR();
return ManifestChange | CleanupChange;
}
ChangeStatus Attributor::updateAA(AbstractAttribute &AA) {
TimeTraceScope TimeScope(
AA.getName() + std::to_string(AA.getIRPosition().getPositionKind()) +
"::updateAA");
assert(Phase == AttributorPhase::UPDATE &&
"We can update AA only in the update stage!");
// Use a new dependence vector for this update.
DependenceVector DV;
DependenceStack.push_back(&DV);
auto &AAState = AA.getState();
ChangeStatus CS = ChangeStatus::UNCHANGED;
if (!isAssumedDead(AA, nullptr, /* CheckBBLivenessOnly */ true))
CS = AA.update(*this);
if (DV.empty()) {
// If the attribute did not query any non-fix information, the state
// will not change and we can indicate that right away.
AAState.indicateOptimisticFixpoint();
}
if (!AAState.isAtFixpoint())
rememberDependences();
// Verify the stack was used properly, that is we pop the dependence vector we
// put there earlier.
DependenceVector *PoppedDV = DependenceStack.pop_back_val();
(void)PoppedDV;
assert(PoppedDV == &DV && "Inconsistent usage of the dependence stack!");
return CS;
}
void Attributor::createShallowWrapper(Function &F) {
assert(!F.isDeclaration() && "Cannot create a wrapper around a declaration!");
Module &M = *F.getParent();
LLVMContext &Ctx = M.getContext();
FunctionType *FnTy = F.getFunctionType();
Function *Wrapper =
Function::Create(FnTy, F.getLinkage(), F.getAddressSpace(), F.getName());
F.setName(""); // set the inside function anonymous
M.getFunctionList().insert(F.getIterator(), Wrapper);
F.setLinkage(GlobalValue::InternalLinkage);
F.replaceAllUsesWith(Wrapper);
assert(F.use_empty() && "Uses remained after wrapper was created!");
// Move the COMDAT section to the wrapper.
// TODO: Check if we need to keep it for F as well.
Wrapper->setComdat(F.getComdat());
F.setComdat(nullptr);
// Copy all metadata and attributes but keep them on F as well.
SmallVector<std::pair<unsigned, MDNode *>, 1> MDs;
F.getAllMetadata(MDs);
for (auto MDIt : MDs)
Wrapper->addMetadata(MDIt.first, *MDIt.second);
Wrapper->setAttributes(F.getAttributes());
// Create the call in the wrapper.
BasicBlock *EntryBB = BasicBlock::Create(Ctx, "entry", Wrapper);
SmallVector<Value *, 8> Args;
Argument *FArgIt = F.arg_begin();
for (Argument &Arg : Wrapper->args()) {
Args.push_back(&Arg);
Arg.setName((FArgIt++)->getName());
}
CallInst *CI = CallInst::Create(&F, Args, "", EntryBB);
CI->setTailCall(true);
CI->addAttribute(AttributeList::FunctionIndex, Attribute::NoInline);
ReturnInst::Create(Ctx, CI->getType()->isVoidTy() ? nullptr : CI, EntryBB);
NumFnShallowWrappersCreated++;
}
/// Make another copy of the function \p F such that the copied version has
/// internal linkage afterwards and can be analysed. Then we replace all uses
/// of the original function to the copied one
///
/// Only non-exactly defined functions that have `linkonce_odr` or `weak_odr`
/// linkage can be internalized because these linkages guarantee that other
/// definitions with the same name have the same semantics as this one
///
static Function *internalizeFunction(Function &F) {
assert(AllowDeepWrapper && "Cannot create a copy if not allowed.");
assert(!F.isDeclaration() && !F.hasExactDefinition() &&
!GlobalValue::isInterposableLinkage(F.getLinkage()) &&
"Trying to internalize function which cannot be internalized.");
Module &M = *F.getParent();
FunctionType *FnTy = F.getFunctionType();
// create a copy of the current function
Function *Copied = Function::Create(FnTy, F.getLinkage(), F.getAddressSpace(),
F.getName() + ".internalized");
ValueToValueMapTy VMap;
auto *NewFArgIt = Copied->arg_begin();
for (auto &Arg : F.args()) {
auto ArgName = Arg.getName();
NewFArgIt->setName(ArgName);
VMap[&Arg] = &(*NewFArgIt++);
}
SmallVector<ReturnInst *, 8> Returns;
// Copy the body of the original function to the new one
CloneFunctionInto(Copied, &F, VMap, CloneFunctionChangeType::LocalChangesOnly,
Returns);
// Set the linakage and visibility late as CloneFunctionInto has some implicit
// requirements.
Copied->setVisibility(GlobalValue::DefaultVisibility);
Copied->setLinkage(GlobalValue::PrivateLinkage);
// Copy metadata
SmallVector<std::pair<unsigned, MDNode *>, 1> MDs;
F.getAllMetadata(MDs);
for (auto MDIt : MDs)
Copied->addMetadata(MDIt.first, *MDIt.second);
M.getFunctionList().insert(F.getIterator(), Copied);
F.replaceAllUsesWith(Copied);
Copied->setDSOLocal(true);
return Copied;
}
bool Attributor::isValidFunctionSignatureRewrite(
Argument &Arg, ArrayRef<Type *> ReplacementTypes) {
auto CallSiteCanBeChanged = [](AbstractCallSite ACS) {
// Forbid the call site to cast the function return type. If we need to
// rewrite these functions we need to re-create a cast for the new call site
// (if the old had uses).
if (!ACS.getCalledFunction() ||
ACS.getInstruction()->getType() !=
ACS.getCalledFunction()->getReturnType())
return false;
// Forbid must-tail calls for now.
return !ACS.isCallbackCall() && !ACS.getInstruction()->isMustTailCall();
};
Function *Fn = Arg.getParent();
// Avoid var-arg functions for now.
if (Fn->isVarArg()) {
LLVM_DEBUG(dbgs() << "[Attributor] Cannot rewrite var-args functions\n");
return false;
}
// Avoid functions with complicated argument passing semantics.
AttributeList FnAttributeList = Fn->getAttributes();
if (FnAttributeList.hasAttrSomewhere(Attribute::Nest) ||
FnAttributeList.hasAttrSomewhere(Attribute::StructRet) ||
FnAttributeList.hasAttrSomewhere(Attribute::InAlloca) ||
FnAttributeList.hasAttrSomewhere(Attribute::Preallocated)) {
LLVM_DEBUG(
dbgs() << "[Attributor] Cannot rewrite due to complex attribute\n");
return false;
}
// Avoid callbacks for now.
bool AllCallSitesKnown;
if (!checkForAllCallSites(CallSiteCanBeChanged, *Fn, true, nullptr,
AllCallSitesKnown)) {
LLVM_DEBUG(dbgs() << "[Attributor] Cannot rewrite all call sites\n");
return false;
}
auto InstPred = [](Instruction &I) {
if (auto *CI = dyn_cast<CallInst>(&I))
return !CI->isMustTailCall();
return true;
};
// Forbid must-tail calls for now.
// TODO:
auto &OpcodeInstMap = InfoCache.getOpcodeInstMapForFunction(*Fn);
if (!checkForAllInstructionsImpl(nullptr, OpcodeInstMap, InstPred, nullptr,
nullptr, {Instruction::Call})) {
LLVM_DEBUG(dbgs() << "[Attributor] Cannot rewrite due to instructions\n");
return false;
}
return true;
}
bool Attributor::registerFunctionSignatureRewrite(
Argument &Arg, ArrayRef<Type *> ReplacementTypes,
ArgumentReplacementInfo::CalleeRepairCBTy &&CalleeRepairCB,
ArgumentReplacementInfo::ACSRepairCBTy &&ACSRepairCB) {
LLVM_DEBUG(dbgs() << "[Attributor] Register new rewrite of " << Arg << " in "
<< Arg.getParent()->getName() << " with "
<< ReplacementTypes.size() << " replacements\n");
assert(isValidFunctionSignatureRewrite(Arg, ReplacementTypes) &&
"Cannot register an invalid rewrite");
Function *Fn = Arg.getParent();
SmallVectorImpl<std::unique_ptr<ArgumentReplacementInfo>> &ARIs =
ArgumentReplacementMap[Fn];
if (ARIs.empty())
ARIs.resize(Fn->arg_size());
// If we have a replacement already with less than or equal new arguments,
// ignore this request.
std::unique_ptr<ArgumentReplacementInfo> &ARI = ARIs[Arg.getArgNo()];
if (ARI && ARI->getNumReplacementArgs() <= ReplacementTypes.size()) {
LLVM_DEBUG(dbgs() << "[Attributor] Existing rewrite is preferred\n");
return false;
}
// If we have a replacement already but we like the new one better, delete
// the old.
ARI.reset();
LLVM_DEBUG(dbgs() << "[Attributor] Register new rewrite of " << Arg << " in "
<< Arg.getParent()->getName() << " with "
<< ReplacementTypes.size() << " replacements\n");
// Remember the replacement.
ARI.reset(new ArgumentReplacementInfo(*this, Arg, ReplacementTypes,
std::move(CalleeRepairCB),
std::move(ACSRepairCB)));
return true;
}
bool Attributor::shouldSeedAttribute(AbstractAttribute &AA) {
bool Result = true;
#ifndef NDEBUG
if (SeedAllowList.size() != 0)
Result =
std::count(SeedAllowList.begin(), SeedAllowList.end(), AA.getName());
Function *Fn = AA.getAnchorScope();
if (FunctionSeedAllowList.size() != 0 && Fn)
Result &= std::count(FunctionSeedAllowList.begin(),
FunctionSeedAllowList.end(), Fn->getName());
#endif
return Result;
}
ChangeStatus Attributor::rewriteFunctionSignatures(
SmallPtrSetImpl<Function *> &ModifiedFns) {
ChangeStatus Changed = ChangeStatus::UNCHANGED;
for (auto &It : ArgumentReplacementMap) {
Function *OldFn = It.getFirst();
// Deleted functions do not require rewrites.
if (!Functions.count(OldFn) || ToBeDeletedFunctions.count(OldFn))
continue;
const SmallVectorImpl<std::unique_ptr<ArgumentReplacementInfo>> &ARIs =
It.getSecond();
assert(ARIs.size() == OldFn->arg_size() && "Inconsistent state!");
SmallVector<Type *, 16> NewArgumentTypes;
SmallVector<AttributeSet, 16> NewArgumentAttributes;
// Collect replacement argument types and copy over existing attributes.
AttributeList OldFnAttributeList = OldFn->getAttributes();
for (Argument &Arg : OldFn->args()) {
if (const std::unique_ptr<ArgumentReplacementInfo> &ARI =
ARIs[Arg.getArgNo()]) {
NewArgumentTypes.append(ARI->ReplacementTypes.begin(),
ARI->ReplacementTypes.end());
NewArgumentAttributes.append(ARI->getNumReplacementArgs(),
AttributeSet());
} else {
NewArgumentTypes.push_back(Arg.getType());
NewArgumentAttributes.push_back(
OldFnAttributeList.getParamAttributes(Arg.getArgNo()));
}
}
FunctionType *OldFnTy = OldFn->getFunctionType();
Type *RetTy = OldFnTy->getReturnType();
// Construct the new function type using the new arguments types.
FunctionType *NewFnTy =
FunctionType::get(RetTy, NewArgumentTypes, OldFnTy->isVarArg());
LLVM_DEBUG(dbgs() << "[Attributor] Function rewrite '" << OldFn->getName()
<< "' from " << *OldFn->getFunctionType() << " to "
<< *NewFnTy << "\n");
// Create the new function body and insert it into the module.
Function *NewFn = Function::Create(NewFnTy, OldFn->getLinkage(),
OldFn->getAddressSpace(), "");
OldFn->getParent()->getFunctionList().insert(OldFn->getIterator(), NewFn);
NewFn->takeName(OldFn);
NewFn->copyAttributesFrom(OldFn);
// Patch the pointer to LLVM function in debug info descriptor.
NewFn->setSubprogram(OldFn->getSubprogram());
OldFn->setSubprogram(nullptr);
// Recompute the parameter attributes list based on the new arguments for
// the function.
LLVMContext &Ctx = OldFn->getContext();
NewFn->setAttributes(AttributeList::get(
Ctx, OldFnAttributeList.getFnAttributes(),
OldFnAttributeList.getRetAttributes(), NewArgumentAttributes));
// Since we have now created the new function, splice the body of the old
// function right into the new function, leaving the old rotting hulk of the
// function empty.
NewFn->getBasicBlockList().splice(NewFn->begin(),
OldFn->getBasicBlockList());
// Fixup block addresses to reference new function.
SmallVector<BlockAddress *, 8u> BlockAddresses;
for (User *U : OldFn->users())
if (auto *BA = dyn_cast<BlockAddress>(U))
BlockAddresses.push_back(BA);
for (auto *BA : BlockAddresses)
BA->replaceAllUsesWith(BlockAddress::get(NewFn, BA->getBasicBlock()));
// Set of all "call-like" instructions that invoke the old function mapped
// to their new replacements.
SmallVector<std::pair<CallBase *, CallBase *>, 8> CallSitePairs;
// Callback to create a new "call-like" instruction for a given one.
auto CallSiteReplacementCreator = [&](AbstractCallSite ACS) {
CallBase *OldCB = cast<CallBase>(ACS.getInstruction());
const AttributeList &OldCallAttributeList = OldCB->getAttributes();
// Collect the new argument operands for the replacement call site.
SmallVector<Value *, 16> NewArgOperands;
SmallVector<AttributeSet, 16> NewArgOperandAttributes;
for (unsigned OldArgNum = 0; OldArgNum < ARIs.size(); ++OldArgNum) {
unsigned NewFirstArgNum = NewArgOperands.size();
(void)NewFirstArgNum; // only used inside assert.
if (const std::unique_ptr<ArgumentReplacementInfo> &ARI =
ARIs[OldArgNum]) {
if (ARI->ACSRepairCB)
ARI->ACSRepairCB(*ARI, ACS, NewArgOperands);
assert(ARI->getNumReplacementArgs() + NewFirstArgNum ==
NewArgOperands.size() &&
"ACS repair callback did not provide as many operand as new "
"types were registered!");
// TODO: Exose the attribute set to the ACS repair callback
NewArgOperandAttributes.append(ARI->ReplacementTypes.size(),
AttributeSet());
} else {
NewArgOperands.push_back(ACS.getCallArgOperand(OldArgNum));
NewArgOperandAttributes.push_back(
OldCallAttributeList.getParamAttributes(OldArgNum));
}
}
assert(NewArgOperands.size() == NewArgOperandAttributes.size() &&
"Mismatch # argument operands vs. # argument operand attributes!");
assert(NewArgOperands.size() == NewFn->arg_size() &&
"Mismatch # argument operands vs. # function arguments!");
SmallVector<OperandBundleDef, 4> OperandBundleDefs;
OldCB->getOperandBundlesAsDefs(OperandBundleDefs);
// Create a new call or invoke instruction to replace the old one.
CallBase *NewCB;
if (InvokeInst *II = dyn_cast<InvokeInst>(OldCB)) {
NewCB =
InvokeInst::Create(NewFn, II->getNormalDest(), II->getUnwindDest(),
NewArgOperands, OperandBundleDefs, "", OldCB);
} else {
auto *NewCI = CallInst::Create(NewFn, NewArgOperands, OperandBundleDefs,
"", OldCB);
NewCI->setTailCallKind(cast<CallInst>(OldCB)->getTailCallKind());
NewCB = NewCI;
}
// Copy over various properties and the new attributes.
NewCB->copyMetadata(*OldCB, {LLVMContext::MD_prof, LLVMContext::MD_dbg});
NewCB->setCallingConv(OldCB->getCallingConv());
NewCB->takeName(OldCB);
NewCB->setAttributes(AttributeList::get(
Ctx, OldCallAttributeList.getFnAttributes(),
OldCallAttributeList.getRetAttributes(), NewArgOperandAttributes));
CallSitePairs.push_back({OldCB, NewCB});
return true;
};
// Use the CallSiteReplacementCreator to create replacement call sites.
bool AllCallSitesKnown;
bool Success = checkForAllCallSites(CallSiteReplacementCreator, *OldFn,
true, nullptr, AllCallSitesKnown);
(void)Success;
assert(Success && "Assumed call site replacement to succeed!");
// Rewire the arguments.
Argument *OldFnArgIt = OldFn->arg_begin();
Argument *NewFnArgIt = NewFn->arg_begin();
for (unsigned OldArgNum = 0; OldArgNum < ARIs.size();
++OldArgNum, ++OldFnArgIt) {
if (const std::unique_ptr<ArgumentReplacementInfo> &ARI =
ARIs[OldArgNum]) {
if (ARI->CalleeRepairCB)
ARI->CalleeRepairCB(*ARI, *NewFn, NewFnArgIt);
NewFnArgIt += ARI->ReplacementTypes.size();
} else {
NewFnArgIt->takeName(&*OldFnArgIt);
OldFnArgIt->replaceAllUsesWith(&*NewFnArgIt);
++NewFnArgIt;
}
}
// Eliminate the instructions *after* we visited all of them.
for (auto &CallSitePair : CallSitePairs) {
CallBase &OldCB = *CallSitePair.first;
CallBase &NewCB = *CallSitePair.second;
assert(OldCB.getType() == NewCB.getType() &&
"Cannot handle call sites with different types!");
ModifiedFns.insert(OldCB.getFunction());
CGUpdater.replaceCallSite(OldCB, NewCB);
OldCB.replaceAllUsesWith(&NewCB);
OldCB.eraseFromParent();
}
// Replace the function in the call graph (if any).
CGUpdater.replaceFunctionWith(*OldFn, *NewFn);
// If the old function was modified and needed to be reanalyzed, the new one
// does now.
if (ModifiedFns.erase(OldFn))
ModifiedFns.insert(NewFn);
Changed = ChangeStatus::CHANGED;
}
return Changed;
}
void InformationCache::initializeInformationCache(const Function &CF,
FunctionInfo &FI) {
// As we do not modify the function here we can remove the const
// withouth breaking implicit assumptions. At the end of the day, we could
// initialize the cache eagerly which would look the same to the users.
Function &F = const_cast<Function &>(CF);
// Walk all instructions to find interesting instructions that might be
// queried by abstract attributes during their initialization or update.
// This has to happen before we create attributes.
for (Instruction &I : instructions(&F)) {
bool IsInterestingOpcode = false;
// To allow easy access to all instructions in a function with a given
// opcode we store them in the InfoCache. As not all opcodes are interesting
// to concrete attributes we only cache the ones that are as identified in
// the following switch.
// Note: There are no concrete attributes now so this is initially empty.
switch (I.getOpcode()) {
default:
assert(!isa<CallBase>(&I) &&
"New call base instruction type needs to be known in the "
"Attributor.");
break;
case Instruction::Call:
// Calls are interesting on their own, additionally:
// For `llvm.assume` calls we also fill the KnowledgeMap as we find them.
// For `must-tail` calls we remember the caller and callee.
if (IntrinsicInst *Assume = dyn_cast<IntrinsicInst>(&I)) {
if (Assume->getIntrinsicID() == Intrinsic::assume)
fillMapFromAssume(*Assume, KnowledgeMap);
} else if (cast<CallInst>(I).isMustTailCall()) {
FI.ContainsMustTailCall = true;
if (const Function *Callee = cast<CallInst>(I).getCalledFunction())
getFunctionInfo(*Callee).CalledViaMustTail = true;
}
LLVM_FALLTHROUGH;
case Instruction::CallBr:
case Instruction::Invoke:
case Instruction::CleanupRet:
case Instruction::CatchSwitch:
case Instruction::AtomicRMW:
case Instruction::AtomicCmpXchg:
case Instruction::Br:
case Instruction::Resume:
case Instruction::Ret:
case Instruction::Load:
// The alignment of a pointer is interesting for loads.
case Instruction::Store:
// The alignment of a pointer is interesting for stores.
IsInterestingOpcode = true;
}
if (IsInterestingOpcode) {
auto *&Insts = FI.OpcodeInstMap[I.getOpcode()];
if (!Insts)
Insts = new (Allocator) InstructionVectorTy();
Insts->push_back(&I);
}
if (I.mayReadOrWriteMemory())
FI.RWInsts.push_back(&I);
}
if (F.hasFnAttribute(Attribute::AlwaysInline) &&
isInlineViable(F).isSuccess())
InlineableFunctions.insert(&F);
}
AAResults *InformationCache::getAAResultsForFunction(const Function &F) {
return AG.getAnalysis<AAManager>(F);
}
InformationCache::FunctionInfo::~FunctionInfo() {
// The instruction vectors are allocated using a BumpPtrAllocator, we need to
// manually destroy them.
for (auto &It : OpcodeInstMap)
It.getSecond()->~InstructionVectorTy();
}
void Attributor::recordDependence(const AbstractAttribute &FromAA,
const AbstractAttribute &ToAA,
DepClassTy DepClass) {
if (DepClass == DepClassTy::NONE)
return;
// If we are outside of an update, thus before the actual fixpoint iteration
// started (= when we create AAs), we do not track dependences because we will
// put all AAs into the initial worklist anyway.
if (DependenceStack.empty())
return;
if (FromAA.getState().isAtFixpoint())
return;
DependenceStack.back()->push_back({&FromAA, &ToAA, DepClass});
}
void Attributor::rememberDependences() {
assert(!DependenceStack.empty() && "No dependences to remember!");
for (DepInfo &DI : *DependenceStack.back()) {
assert((DI.DepClass == DepClassTy::REQUIRED ||
DI.DepClass == DepClassTy::OPTIONAL) &&
"Expected required or optional dependence (1 bit)!");
auto &DepAAs = const_cast<AbstractAttribute &>(*DI.FromAA).Deps;
DepAAs.push_back(AbstractAttribute::DepTy(
const_cast<AbstractAttribute *>(DI.ToAA), unsigned(DI.DepClass)));
}
}
void Attributor::identifyDefaultAbstractAttributes(Function &F) {
if (!VisitedFunctions.insert(&F).second)
return;
if (F.isDeclaration())
return;
// In non-module runs we need to look at the call sites of a function to
// determine if it is part of a must-tail call edge. This will influence what
// attributes we can derive.
InformationCache::FunctionInfo &FI = InfoCache.getFunctionInfo(F);
if (!isModulePass() && !FI.CalledViaMustTail) {
for (const Use &U : F.uses())
if (const auto *CB = dyn_cast<CallBase>(U.getUser()))
if (CB->isCallee(&U) && CB->isMustTailCall())
FI.CalledViaMustTail = true;
}
IRPosition FPos = IRPosition::function(F);
// Check for dead BasicBlocks in every function.
// We need dead instruction detection because we do not want to deal with
// broken IR in which SSA rules do not apply.
getOrCreateAAFor<AAIsDead>(FPos);
// Every function might be "will-return".
getOrCreateAAFor<AAWillReturn>(FPos);
// Every function might contain instructions that cause "undefined behavior".
getOrCreateAAFor<AAUndefinedBehavior>(FPos);
// Every function can be nounwind.
getOrCreateAAFor<AANoUnwind>(FPos);
// Every function might be marked "nosync"
getOrCreateAAFor<AANoSync>(FPos);
// Every function might be "no-free".
getOrCreateAAFor<AANoFree>(FPos);
// Every function might be "no-return".
getOrCreateAAFor<AANoReturn>(FPos);
// Every function might be "no-recurse".
getOrCreateAAFor<AANoRecurse>(FPos);
// Every function might be "readnone/readonly/writeonly/...".
getOrCreateAAFor<AAMemoryBehavior>(FPos);
// Every function can be "readnone/argmemonly/inaccessiblememonly/...".
getOrCreateAAFor<AAMemoryLocation>(FPos);
// Every function might be applicable for Heap-To-Stack conversion.
if (EnableHeapToStack)
getOrCreateAAFor<AAHeapToStack>(FPos);
// Return attributes are only appropriate if the return type is non void.
Type *ReturnType = F.getReturnType();
if (!ReturnType->isVoidTy()) {
// Argument attribute "returned" --- Create only one per function even
// though it is an argument attribute.
getOrCreateAAFor<AAReturnedValues>(FPos);
IRPosition RetPos = IRPosition::returned(F);
// Every returned value might be dead.
getOrCreateAAFor<AAIsDead>(RetPos);
// Every function might be simplified.
getOrCreateAAFor<AAValueSimplify>(RetPos);
// Every returned value might be marked noundef.
getOrCreateAAFor<AANoUndef>(RetPos);
if (ReturnType->isPointerTy()) {
// Every function with pointer return type might be marked align.
getOrCreateAAFor<AAAlign>(RetPos);
// Every function with pointer return type might be marked nonnull.
getOrCreateAAFor<AANonNull>(RetPos);
// Every function with pointer return type might be marked noalias.
getOrCreateAAFor<AANoAlias>(RetPos);
// Every function with pointer return type might be marked
// dereferenceable.
getOrCreateAAFor<AADereferenceable>(RetPos);
}
}
for (Argument &Arg : F.args()) {
IRPosition ArgPos = IRPosition::argument(Arg);
// Every argument might be simplified.
getOrCreateAAFor<AAValueSimplify>(ArgPos);
// Every argument might be dead.
getOrCreateAAFor<AAIsDead>(ArgPos);
// Every argument might be marked noundef.
getOrCreateAAFor<AANoUndef>(ArgPos);
if (Arg.getType()->isPointerTy()) {
// Every argument with pointer type might be marked nonnull.
getOrCreateAAFor<AANonNull>(ArgPos);
// Every argument with pointer type might be marked noalias.
getOrCreateAAFor<AANoAlias>(ArgPos);
// Every argument with pointer type might be marked dereferenceable.
getOrCreateAAFor<AADereferenceable>(ArgPos);
// Every argument with pointer type might be marked align.
getOrCreateAAFor<AAAlign>(ArgPos);
// Every argument with pointer type might be marked nocapture.
getOrCreateAAFor<AANoCapture>(ArgPos);
// Every argument with pointer type might be marked
// "readnone/readonly/writeonly/..."
getOrCreateAAFor<AAMemoryBehavior>(ArgPos);
// Every argument with pointer type might be marked nofree.
getOrCreateAAFor<AANoFree>(ArgPos);
// Every argument with pointer type might be privatizable (or promotable)
getOrCreateAAFor<AAPrivatizablePtr>(ArgPos);
}
}
auto CallSitePred = [&](Instruction &I) -> bool {
auto &CB = cast<CallBase>(I);
IRPosition CBRetPos = IRPosition::callsite_returned(CB);
// Call sites might be dead if they do not have side effects and no live
// users. The return value might be dead if there are no live users.
getOrCreateAAFor<AAIsDead>(CBRetPos);
Function *Callee = CB.getCalledFunction();
// TODO: Even if the callee is not known now we might be able to simplify
// the call/callee.
if (!Callee)
return true;
// Skip declarations except if annotations on their call sites were
// explicitly requested.
if (!AnnotateDeclarationCallSites && Callee->isDeclaration() &&
!Callee->hasMetadata(LLVMContext::MD_callback))
return true;
if (!Callee->getReturnType()->isVoidTy() && !CB.use_empty()) {
IRPosition CBRetPos = IRPosition::callsite_returned(CB);
// Call site return integer values might be limited by a constant range.
if (Callee->getReturnType()->isIntegerTy())
getOrCreateAAFor<AAValueConstantRange>(CBRetPos);
}
for (int I = 0, E = CB.getNumArgOperands(); I < E; ++I) {
IRPosition CBArgPos = IRPosition::callsite_argument(CB, I);
// Every call site argument might be dead.
getOrCreateAAFor<AAIsDead>(CBArgPos);
// Call site argument might be simplified.
getOrCreateAAFor<AAValueSimplify>(CBArgPos);
// Every call site argument might be marked "noundef".
getOrCreateAAFor<AANoUndef>(CBArgPos);
if (!CB.getArgOperand(I)->getType()->isPointerTy())
continue;
// Call site argument attribute "non-null".
getOrCreateAAFor<AANonNull>(CBArgPos);
// Call site argument attribute "nocapture".
getOrCreateAAFor<AANoCapture>(CBArgPos);
// Call site argument attribute "no-alias".
getOrCreateAAFor<AANoAlias>(CBArgPos);
// Call site argument attribute "dereferenceable".
getOrCreateAAFor<AADereferenceable>(CBArgPos);
// Call site argument attribute "align".
getOrCreateAAFor<AAAlign>(CBArgPos);
// Call site argument attribute
// "readnone/readonly/writeonly/..."
getOrCreateAAFor<AAMemoryBehavior>(CBArgPos);
// Call site argument attribute "nofree".
getOrCreateAAFor<AANoFree>(CBArgPos);
}
return true;
};
auto &OpcodeInstMap = InfoCache.getOpcodeInstMapForFunction(F);
bool Success;
Success = checkForAllInstructionsImpl(
nullptr, OpcodeInstMap, CallSitePred, nullptr, nullptr,
{(unsigned)Instruction::Invoke, (unsigned)Instruction::CallBr,
(unsigned)Instruction::Call});
(void)Success;
assert(Success && "Expected the check call to be successful!");
auto LoadStorePred = [&](Instruction &I) -> bool {
if (isa<LoadInst>(I))
getOrCreateAAFor<AAAlign>(
IRPosition::value(*cast<LoadInst>(I).getPointerOperand()));
else
getOrCreateAAFor<AAAlign>(
IRPosition::value(*cast<StoreInst>(I).getPointerOperand()));
return true;
};
Success = checkForAllInstructionsImpl(
nullptr, OpcodeInstMap, LoadStorePred, nullptr, nullptr,
{(unsigned)Instruction::Load, (unsigned)Instruction::Store});
(void)Success;
assert(Success && "Expected the check call to be successful!");
}
/// Helpers to ease debugging through output streams and print calls.
///
///{
raw_ostream &llvm::operator<<(raw_ostream &OS, ChangeStatus S) {
return OS << (S == ChangeStatus::CHANGED ? "changed" : "unchanged");
}
raw_ostream &llvm::operator<<(raw_ostream &OS, IRPosition::Kind AP) {
switch (AP) {
case IRPosition::IRP_INVALID:
return OS << "inv";
case IRPosition::IRP_FLOAT:
return OS << "flt";
case IRPosition::IRP_RETURNED:
return OS << "fn_ret";
case IRPosition::IRP_CALL_SITE_RETURNED:
return OS << "cs_ret";
case IRPosition::IRP_FUNCTION:
return OS << "fn";
case IRPosition::IRP_CALL_SITE:
return OS << "cs";
case IRPosition::IRP_ARGUMENT:
return OS << "arg";
case IRPosition::IRP_CALL_SITE_ARGUMENT:
return OS << "cs_arg";
}
llvm_unreachable("Unknown attribute position!");
}
raw_ostream &llvm::operator<<(raw_ostream &OS, const IRPosition &Pos) {
const Value &AV = Pos.getAssociatedValue();
OS << "{" << Pos.getPositionKind() << ":" << AV.getName() << " ["
<< Pos.getAnchorValue().getName() << "@" << Pos.getCallSiteArgNo() << "]";
if (Pos.hasCallBaseContext())
OS << "[cb_context:" << *Pos.getCallBaseContext() << "]";
return OS << "}";
}
raw_ostream &llvm::operator<<(raw_ostream &OS, const IntegerRangeState &S) {
OS << "range-state(" << S.getBitWidth() << ")<";
S.getKnown().print(OS);
OS << " / ";
S.getAssumed().print(OS);
OS << ">";
return OS << static_cast<const AbstractState &>(S);
}
raw_ostream &llvm::operator<<(raw_ostream &OS, const AbstractState &S) {
return OS << (!S.isValidState() ? "top" : (S.isAtFixpoint() ? "fix" : ""));
}
raw_ostream &llvm::operator<<(raw_ostream &OS, const AbstractAttribute &AA) {
AA.print(OS);
return OS;
}
raw_ostream &llvm::operator<<(raw_ostream &OS,
const PotentialConstantIntValuesState &S) {
OS << "set-state(< {";
if (!S.isValidState())
OS << "full-set";
else {
for (auto &it : S.getAssumedSet())
OS << it << ", ";
if (S.undefIsContained())
OS << "undef ";
}
OS << "} >)";
return OS;
}
void AbstractAttribute::print(raw_ostream &OS) const {
OS << "[";
OS << getName();
OS << "] for CtxI ";
if (auto *I = getCtxI()) {
OS << "'";
I->print(OS);
OS << "'";
} else
OS << "<<null inst>>";
OS << " at position " << getIRPosition() << " with state " << getAsStr()
<< '\n';
}
void AbstractAttribute::printWithDeps(raw_ostream &OS) const {
print(OS);
for (const auto &DepAA : Deps) {
auto *AA = DepAA.getPointer();
OS << " updates ";
AA->print(OS);
}
OS << '\n';
}
///}
/// ----------------------------------------------------------------------------
/// Pass (Manager) Boilerplate
/// ----------------------------------------------------------------------------
static bool runAttributorOnFunctions(InformationCache &InfoCache,
SetVector<Function *> &Functions,
AnalysisGetter &AG,
CallGraphUpdater &CGUpdater,
bool DeleteFns) {
if (Functions.empty())
return false;
LLVM_DEBUG(dbgs() << "[Attributor] Run on module with " << Functions.size()
<< " functions.\n");
// Create an Attributor and initially empty information cache that is filled
// while we identify default attribute opportunities.
Attributor A(Functions, InfoCache, CGUpdater, /* Allowed */ nullptr,
DeleteFns);
// Create shallow wrappers for all functions that are not IPO amendable
if (AllowShallowWrappers)
for (Function *F : Functions)
if (!A.isFunctionIPOAmendable(*F))
Attributor::createShallowWrapper(*F);
// Internalize non-exact functions
// TODO: for now we eagerly internalize functions without calculating the
// cost, we need a cost interface to determine whether internalizing
// a function is "benefitial"
if (AllowDeepWrapper) {
unsigned FunSize = Functions.size();
for (unsigned u = 0; u < FunSize; u++) {
Function *F = Functions[u];
if (!F->isDeclaration() && !F->isDefinitionExact() && F->getNumUses() &&
!GlobalValue::isInterposableLinkage(F->getLinkage())) {
Function *NewF = internalizeFunction(*F);
Functions.insert(NewF);
// Update call graph
CGUpdater.replaceFunctionWith(*F, *NewF);
for (const Use &U : NewF->uses())
if (CallBase *CB = dyn_cast<CallBase>(U.getUser())) {
auto *CallerF = CB->getCaller();
CGUpdater.reanalyzeFunction(*CallerF);
}
}
}
}
for (Function *F : Functions) {
if (F->hasExactDefinition())
NumFnWithExactDefinition++;
else
NumFnWithoutExactDefinition++;
// We look at internal functions only on-demand but if any use is not a
// direct call or outside the current set of analyzed functions, we have
// to do it eagerly.
if (F->hasLocalLinkage()) {
if (llvm::all_of(F->uses(), [&Functions](const Use &U) {
const auto *CB = dyn_cast<CallBase>(U.getUser());
return CB && CB->isCallee(&U) &&
Functions.count(const_cast<Function *>(CB->getCaller()));
}))
continue;
}
// Populate the Attributor with abstract attribute opportunities in the
// function and the information cache with IR information.
A.identifyDefaultAbstractAttributes(*F);
}
ChangeStatus Changed = A.run();
LLVM_DEBUG(dbgs() << "[Attributor] Done with " << Functions.size()
<< " functions, result: " << Changed << ".\n");
return Changed == ChangeStatus::CHANGED;
}
void AADepGraph::viewGraph() { llvm::ViewGraph(this, "Dependency Graph"); }
void AADepGraph::dumpGraph() {
static std::atomic<int> CallTimes;
std::string Prefix;
if (!DepGraphDotFileNamePrefix.empty())
Prefix = DepGraphDotFileNamePrefix;
else
Prefix = "dep_graph";
std::string Filename =
Prefix + "_" + std::to_string(CallTimes.load()) + ".dot";
outs() << "Dependency graph dump to " << Filename << ".\n";
std::error_code EC;
raw_fd_ostream File(Filename, EC, sys::fs::OF_Text);
if (!EC)
llvm::WriteGraph(File, this);
CallTimes++;
}
void AADepGraph::print() {
for (auto DepAA : SyntheticRoot.Deps)
cast<AbstractAttribute>(DepAA.getPointer())->printWithDeps(outs());
}
PreservedAnalyses AttributorPass::run(Module &M, ModuleAnalysisManager &AM) {
FunctionAnalysisManager &FAM =
AM.getResult<FunctionAnalysisManagerModuleProxy>(M).getManager();
AnalysisGetter AG(FAM);
SetVector<Function *> Functions;
for (Function &F : M)
Functions.insert(&F);
CallGraphUpdater CGUpdater;
BumpPtrAllocator Allocator;
InformationCache InfoCache(M, AG, Allocator, /* CGSCC */ nullptr);
if (runAttributorOnFunctions(InfoCache, Functions, AG, CGUpdater,
/* DeleteFns */ true)) {
// FIXME: Think about passes we will preserve and add them here.
return PreservedAnalyses::none();
}
return PreservedAnalyses::all();
}
PreservedAnalyses AttributorCGSCCPass::run(LazyCallGraph::SCC &C,
CGSCCAnalysisManager &AM,
LazyCallGraph &CG,
CGSCCUpdateResult &UR) {
FunctionAnalysisManager &FAM =
AM.getResult<FunctionAnalysisManagerCGSCCProxy>(C, CG).getManager();
AnalysisGetter AG(FAM);
SetVector<Function *> Functions;
for (LazyCallGraph::Node &N : C)
Functions.insert(&N.getFunction());
if (Functions.empty())
return PreservedAnalyses::all();
Module &M = *Functions.back()->getParent();
CallGraphUpdater CGUpdater;
CGUpdater.initialize(CG, C, AM, UR);
BumpPtrAllocator Allocator;
InformationCache InfoCache(M, AG, Allocator, /* CGSCC */ &Functions);
if (runAttributorOnFunctions(InfoCache, Functions, AG, CGUpdater,
/* DeleteFns */ false)) {
// FIXME: Think about passes we will preserve and add them here.
PreservedAnalyses PA;
PA.preserve<FunctionAnalysisManagerCGSCCProxy>();
return PA;
}
return PreservedAnalyses::all();
}
namespace llvm {
template <> struct GraphTraits<AADepGraphNode *> {
using NodeRef = AADepGraphNode *;
using DepTy = PointerIntPair<AADepGraphNode *, 1>;
using EdgeRef = PointerIntPair<AADepGraphNode *, 1>;
static NodeRef getEntryNode(AADepGraphNode *DGN) { return DGN; }
static NodeRef DepGetVal(DepTy &DT) { return DT.getPointer(); }
using ChildIteratorType =
mapped_iterator<TinyPtrVector<DepTy>::iterator, decltype(&DepGetVal)>;
using ChildEdgeIteratorType = TinyPtrVector<DepTy>::iterator;
static ChildIteratorType child_begin(NodeRef N) { return N->child_begin(); }
static ChildIteratorType child_end(NodeRef N) { return N->child_end(); }
};
template <>
struct GraphTraits<AADepGraph *> : public GraphTraits<AADepGraphNode *> {
static NodeRef getEntryNode(AADepGraph *DG) { return DG->GetEntryNode(); }
using nodes_iterator =
mapped_iterator<TinyPtrVector<DepTy>::iterator, decltype(&DepGetVal)>;
static nodes_iterator nodes_begin(AADepGraph *DG) { return DG->begin(); }
static nodes_iterator nodes_end(AADepGraph *DG) { return DG->end(); }
};
template <> struct DOTGraphTraits<AADepGraph *> : public DefaultDOTGraphTraits {
DOTGraphTraits(bool isSimple = false) : DefaultDOTGraphTraits(isSimple) {}
static std::string getNodeLabel(const AADepGraphNode *Node,
const AADepGraph *DG) {
std::string AAString;
raw_string_ostream O(AAString);
Node->print(O);
return AAString;
}
};
} // end namespace llvm
namespace {
struct AttributorLegacyPass : public ModulePass {
static char ID;
AttributorLegacyPass() : ModulePass(ID) {
initializeAttributorLegacyPassPass(*PassRegistry::getPassRegistry());
}
bool runOnModule(Module &M) override {
if (skipModule(M))
return false;
AnalysisGetter AG;
SetVector<Function *> Functions;
for (Function &F : M)
Functions.insert(&F);
CallGraphUpdater CGUpdater;
BumpPtrAllocator Allocator;
InformationCache InfoCache(M, AG, Allocator, /* CGSCC */ nullptr);
return runAttributorOnFunctions(InfoCache, Functions, AG, CGUpdater,
/* DeleteFns*/ true);
}
void getAnalysisUsage(AnalysisUsage &AU) const override {
// FIXME: Think about passes we will preserve and add them here.
AU.addRequired<TargetLibraryInfoWrapperPass>();
}
};
struct AttributorCGSCCLegacyPass : public CallGraphSCCPass {
static char ID;
AttributorCGSCCLegacyPass() : CallGraphSCCPass(ID) {
initializeAttributorCGSCCLegacyPassPass(*PassRegistry::getPassRegistry());
}
bool runOnSCC(CallGraphSCC &SCC) override {
if (skipSCC(SCC))
return false;
SetVector<Function *> Functions;
for (CallGraphNode *CGN : SCC)
if (Function *Fn = CGN->getFunction())
if (!Fn->isDeclaration())
Functions.insert(Fn);
if (Functions.empty())
return false;
AnalysisGetter AG;
CallGraph &CG = const_cast<CallGraph &>(SCC.getCallGraph());
CallGraphUpdater CGUpdater;
CGUpdater.initialize(CG, SCC);
Module &M = *Functions.back()->getParent();
BumpPtrAllocator Allocator;
InformationCache InfoCache(M, AG, Allocator, /* CGSCC */ &Functions);
return runAttributorOnFunctions(InfoCache, Functions, AG, CGUpdater,
/* DeleteFns */ false);
}
void getAnalysisUsage(AnalysisUsage &AU) const override {
// FIXME: Think about passes we will preserve and add them here.
AU.addRequired<TargetLibraryInfoWrapperPass>();
CallGraphSCCPass::getAnalysisUsage(AU);
}
};
} // end anonymous namespace
Pass *llvm::createAttributorLegacyPass() { return new AttributorLegacyPass(); }
Pass *llvm::createAttributorCGSCCLegacyPass() {
return new AttributorCGSCCLegacyPass();
}
char AttributorLegacyPass::ID = 0;
char AttributorCGSCCLegacyPass::ID = 0;
INITIALIZE_PASS_BEGIN(AttributorLegacyPass, "attributor",
"Deduce and propagate attributes", false, false)
INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
INITIALIZE_PASS_END(AttributorLegacyPass, "attributor",
"Deduce and propagate attributes", false, false)
INITIALIZE_PASS_BEGIN(AttributorCGSCCLegacyPass, "attributor-cgscc",
"Deduce and propagate attributes (CGSCC pass)", false,
false)
INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
INITIALIZE_PASS_DEPENDENCY(CallGraphWrapperPass)
INITIALIZE_PASS_END(AttributorCGSCCLegacyPass, "attributor-cgscc",
"Deduce and propagate attributes (CGSCC pass)", false,
false)