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llvm / llvm-project / 4e69258bf390b51ed5bc65e7cea4cbcfbb62bd44 / . / llvm / lib / Transforms / Scalar / InferAddressSpaces.cpp
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//===- InferAddressSpace.cpp - --------------------------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// CUDA C/C++ includes memory space designation as variable type qualifers (such
// as __global__ and __shared__). Knowing the space of a memory access allows
// CUDA compilers to emit faster PTX loads and stores. For example, a load from
// shared memory can be translated to `ld.shared` which is roughly 10% faster
// than a generic `ld` on an NVIDIA Tesla K40c.
//
// Unfortunately, type qualifiers only apply to variable declarations, so CUDA
// compilers must infer the memory space of an address expression from
// type-qualified variables.
//
// LLVM IR uses non-zero (so-called) specific address spaces to represent memory
// spaces (e.g. addrspace(3) means shared memory). The Clang frontend
// places only type-qualified variables in specific address spaces, and then
// conservatively `addrspacecast`s each type-qualified variable to addrspace(0)
// (so-called the generic address space) for other instructions to use.
//
// For example, the Clang translates the following CUDA code
// __shared__ float a[10];
// float v = a[i];
// to
// %0 = addrspacecast [10 x float] addrspace(3)* @a to [10 x float]*
// %1 = gep [10 x float], [10 x float]* %0, i64 0, i64 %i
// %v = load float, float* %1 ; emits ld.f32
// @a is in addrspace(3) since it's type-qualified, but its use from %1 is
// redirected to %0 (the generic version of @a).
//
// The optimization implemented in this file propagates specific address spaces
// from type-qualified variable declarations to its users. For example, it
// optimizes the above IR to
// %1 = gep [10 x float] addrspace(3)* @a, i64 0, i64 %i
// %v = load float addrspace(3)* %1 ; emits ld.shared.f32
// propagating the addrspace(3) from @a to %1. As the result, the NVPTX
// codegen is able to emit ld.shared.f32 for %v.
//
// Address space inference works in two steps. First, it uses a data-flow
// analysis to infer as many generic pointers as possible to point to only one
// specific address space. In the above example, it can prove that %1 only
// points to addrspace(3). This algorithm was published in
// CUDA: Compiling and optimizing for a GPU platform
// Chakrabarti, Grover, Aarts, Kong, Kudlur, Lin, Marathe, Murphy, Wang
// ICCS 2012
//
// Then, address space inference replaces all refinable generic pointers with
// equivalent specific pointers.
//
// The major challenge of implementing this optimization is handling PHINodes,
// which may create loops in the data flow graph. This brings two complications.
//
// First, the data flow analysis in Step 1 needs to be circular. For example,
// %generic.input = addrspacecast float addrspace(3)* %input to float*
// loop:
// %y = phi [ %generic.input, %y2 ]
// %y2 = getelementptr %y, 1
// %v = load %y2
// br ..., label %loop, ...
// proving %y specific requires proving both %generic.input and %y2 specific,
// but proving %y2 specific circles back to %y. To address this complication,
// the data flow analysis operates on a lattice:
// uninitialized > specific address spaces > generic.
// All address expressions (our implementation only considers phi, bitcast,
// addrspacecast, and getelementptr) start with the uninitialized address space.
// The monotone transfer function moves the address space of a pointer down a
// lattice path from uninitialized to specific and then to generic. A join
// operation of two different specific address spaces pushes the expression down
// to the generic address space. The analysis completes once it reaches a fixed
// point.
//
// Second, IR rewriting in Step 2 also needs to be circular. For example,
// converting %y to addrspace(3) requires the compiler to know the converted
// %y2, but converting %y2 needs the converted %y. To address this complication,
// we break these cycles using "poison" placeholders. When converting an
// instruction `I` to a new address space, if its operand `Op` is not converted
// yet, we let `I` temporarily use `poison` and fix all the uses later.
// For instance, our algorithm first converts %y to
// %y' = phi float addrspace(3)* [ %input, poison ]
// Then, it converts %y2 to
// %y2' = getelementptr %y', 1
// Finally, it fixes the poison in %y' so that
// %y' = phi float addrspace(3)* [ %input, %y2' ]
//
//===----------------------------------------------------------------------===//
#include "llvm/Transforms/Scalar/InferAddressSpaces.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/DenseSet.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/Analysis/AssumptionCache.h"
#include "llvm/Analysis/TargetTransformInfo.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/IR/BasicBlock.h"
#include "llvm/IR/Constant.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/Dominators.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/InstIterator.h"
#include "llvm/IR/Instruction.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/Intrinsics.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/Operator.h"
#include "llvm/IR/PassManager.h"
#include "llvm/IR/Type.h"
#include "llvm/IR/Use.h"
#include "llvm/IR/User.h"
#include "llvm/IR/Value.h"
#include "llvm/IR/ValueHandle.h"
#include "llvm/InitializePasses.h"
#include "llvm/Pass.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Transforms/Scalar.h"
#include "llvm/Transforms/Utils/Local.h"
#include "llvm/Transforms/Utils/ValueMapper.h"
#include <cassert>
#include <iterator>
#include <limits>
#include <utility>
#include <vector>
#define DEBUG_TYPE "infer-address-spaces"
using namespace llvm;
static cl::opt<bool> AssumeDefaultIsFlatAddressSpace(
"assume-default-is-flat-addrspace", cl::init(false), cl::ReallyHidden,
cl::desc("The default address space is assumed as the flat address space. "
"This is mainly for test purpose."));
static const unsigned UninitializedAddressSpace =
std::numeric_limits<unsigned>::max();
namespace {
using ValueToAddrSpaceMapTy = DenseMap<const Value *, unsigned>;
// Different from ValueToAddrSpaceMapTy, where a new addrspace is inferred on
// the *def* of a value, PredicatedAddrSpaceMapTy is map where a new
// addrspace is inferred on the *use* of a pointer. This map is introduced to
// infer addrspace from the addrspace predicate assumption built from assume
// intrinsic. In that scenario, only specific uses (under valid assumption
// context) could be inferred with a new addrspace.
using PredicatedAddrSpaceMapTy =
DenseMap<std::pair<const Value *, const Value *>, unsigned>;
using PostorderStackTy = llvm::SmallVector<PointerIntPair<Value *, 1, bool>, 4>;
class InferAddressSpaces : public FunctionPass {
unsigned FlatAddrSpace = 0;
public:
static char ID;
InferAddressSpaces()
: FunctionPass(ID), FlatAddrSpace(UninitializedAddressSpace) {
initializeInferAddressSpacesPass(*PassRegistry::getPassRegistry());
}
InferAddressSpaces(unsigned AS) : FunctionPass(ID), FlatAddrSpace(AS) {
initializeInferAddressSpacesPass(*PassRegistry::getPassRegistry());
}
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.setPreservesCFG();
AU.addPreserved<DominatorTreeWrapperPass>();
AU.addRequired<AssumptionCacheTracker>();
AU.addRequired<TargetTransformInfoWrapperPass>();
}
bool runOnFunction(Function &F) override;
};
class InferAddressSpacesImpl {
AssumptionCache &AC;
Function *F = nullptr;
const DominatorTree *DT = nullptr;
const TargetTransformInfo *TTI = nullptr;
const DataLayout *DL = nullptr;
/// Target specific address space which uses of should be replaced if
/// possible.
unsigned FlatAddrSpace = 0;
// Try to update the address space of V. If V is updated, returns true and
// false otherwise.
bool updateAddressSpace(const Value &V,
ValueToAddrSpaceMapTy &InferredAddrSpace,
PredicatedAddrSpaceMapTy &PredicatedAS) const;
// Tries to infer the specific address space of each address expression in
// Postorder.
void inferAddressSpaces(ArrayRef<WeakTrackingVH> Postorder,
ValueToAddrSpaceMapTy &InferredAddrSpace,
PredicatedAddrSpaceMapTy &PredicatedAS) const;
bool isSafeToCastConstAddrSpace(Constant *C, unsigned NewAS) const;
Value *cloneInstructionWithNewAddressSpace(
Instruction *I, unsigned NewAddrSpace,
const ValueToValueMapTy &ValueWithNewAddrSpace,
const PredicatedAddrSpaceMapTy &PredicatedAS,
SmallVectorImpl<const Use *> *PoisonUsesToFix) const;
void performPointerReplacement(
Value *V, Value *NewV, Use &U, ValueToValueMapTy &ValueWithNewAddrSpace,
SmallVectorImpl<Instruction *> &DeadInstructions) const;
// Changes the flat address expressions in function F to point to specific
// address spaces if InferredAddrSpace says so. Postorder is the postorder of
// all flat expressions in the use-def graph of function F.
bool rewriteWithNewAddressSpaces(
ArrayRef<WeakTrackingVH> Postorder,
const ValueToAddrSpaceMapTy &InferredAddrSpace,
const PredicatedAddrSpaceMapTy &PredicatedAS) const;
void appendsFlatAddressExpressionToPostorderStack(
Value *V, PostorderStackTy &PostorderStack,
DenseSet<Value *> &Visited) const;
bool rewriteIntrinsicOperands(IntrinsicInst *II, Value *OldV,
Value *NewV) const;
void collectRewritableIntrinsicOperands(IntrinsicInst *II,
PostorderStackTy &PostorderStack,
DenseSet<Value *> &Visited) const;
std::vector<WeakTrackingVH> collectFlatAddressExpressions(Function &F) const;
Value *cloneValueWithNewAddressSpace(
Value *V, unsigned NewAddrSpace,
const ValueToValueMapTy &ValueWithNewAddrSpace,
const PredicatedAddrSpaceMapTy &PredicatedAS,
SmallVectorImpl<const Use *> *PoisonUsesToFix) const;
unsigned joinAddressSpaces(unsigned AS1, unsigned AS2) const;
unsigned getPredicatedAddrSpace(const Value &PtrV,
const Value *UserCtx) const;
public:
InferAddressSpacesImpl(AssumptionCache &AC, const DominatorTree *DT,
const TargetTransformInfo *TTI, unsigned FlatAddrSpace)
: AC(AC), DT(DT), TTI(TTI), FlatAddrSpace(FlatAddrSpace) {}
bool run(Function &F);
};
} // end anonymous namespace
char InferAddressSpaces::ID = 0;
INITIALIZE_PASS_BEGIN(InferAddressSpaces, DEBUG_TYPE, "Infer address spaces",
false, false)
INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)
INITIALIZE_PASS_DEPENDENCY(TargetTransformInfoWrapperPass)
INITIALIZE_PASS_END(InferAddressSpaces, DEBUG_TYPE, "Infer address spaces",
false, false)
static Type *getPtrOrVecOfPtrsWithNewAS(Type *Ty, unsigned NewAddrSpace) {
assert(Ty->isPtrOrPtrVectorTy());
PointerType *NPT = PointerType::get(Ty->getContext(), NewAddrSpace);
return Ty->getWithNewType(NPT);
}
// Check whether that's no-op pointer bicast using a pair of
// `ptrtoint`/`inttoptr` due to the missing no-op pointer bitcast over
// different address spaces.
static bool isNoopPtrIntCastPair(const Operator *I2P, const DataLayout &DL,
const TargetTransformInfo *TTI) {
assert(I2P->getOpcode() == Instruction::IntToPtr);
auto *P2I = dyn_cast<Operator>(I2P->getOperand(0));
if (!P2I || P2I->getOpcode() != Instruction::PtrToInt)
return false;
// Check it's really safe to treat that pair of `ptrtoint`/`inttoptr` as a
// no-op cast. Besides checking both of them are no-op casts, as the
// reinterpreted pointer may be used in other pointer arithmetic, we also
// need to double-check that through the target-specific hook. That ensures
// the underlying target also agrees that's a no-op address space cast and
// pointer bits are preserved.
// The current IR spec doesn't have clear rules on address space casts,
// especially a clear definition for pointer bits in non-default address
// spaces. It would be undefined if that pointer is dereferenced after an
// invalid reinterpret cast. Also, due to the unclearness for the meaning of
// bits in non-default address spaces in the current spec, the pointer
// arithmetic may also be undefined after invalid pointer reinterpret cast.
// However, as we confirm through the target hooks that it's a no-op
// addrspacecast, it doesn't matter since the bits should be the same.
unsigned P2IOp0AS = P2I->getOperand(0)->getType()->getPointerAddressSpace();
unsigned I2PAS = I2P->getType()->getPointerAddressSpace();
return CastInst::isNoopCast(Instruction::CastOps(I2P->getOpcode()),
I2P->getOperand(0)->getType(), I2P->getType(),
DL) &&
CastInst::isNoopCast(Instruction::CastOps(P2I->getOpcode()),
P2I->getOperand(0)->getType(), P2I->getType(),
DL) &&
(P2IOp0AS == I2PAS || TTI->isNoopAddrSpaceCast(P2IOp0AS, I2PAS));
}
// Returns true if V is an address expression.
// TODO: Currently, we consider only phi, bitcast, addrspacecast, and
// getelementptr operators.
static bool isAddressExpression(const Value &V, const DataLayout &DL,
const TargetTransformInfo *TTI) {
const Operator *Op = dyn_cast<Operator>(&V);
if (!Op)
return false;
switch (Op->getOpcode()) {
case Instruction::PHI:
assert(Op->getType()->isPtrOrPtrVectorTy());
return true;
case Instruction::BitCast:
case Instruction::AddrSpaceCast:
case Instruction::GetElementPtr:
return true;
case Instruction::Select:
return Op->getType()->isPtrOrPtrVectorTy();
case Instruction::Call: {
const IntrinsicInst *II = dyn_cast<IntrinsicInst>(&V);
return II && II->getIntrinsicID() == Intrinsic::ptrmask;
}
case Instruction::IntToPtr:
return isNoopPtrIntCastPair(Op, DL, TTI);
default:
// That value is an address expression if it has an assumed address space.
return TTI->getAssumedAddrSpace(&V) != UninitializedAddressSpace;
}
}
// Returns the pointer operands of V.
//
// Precondition: V is an address expression.
static SmallVector<Value *, 2>
getPointerOperands(const Value &V, const DataLayout &DL,
const TargetTransformInfo *TTI) {
const Operator &Op = cast<Operator>(V);
switch (Op.getOpcode()) {
case Instruction::PHI: {
auto IncomingValues = cast<PHINode>(Op).incoming_values();
return {IncomingValues.begin(), IncomingValues.end()};
}
case Instruction::BitCast:
case Instruction::AddrSpaceCast:
case Instruction::GetElementPtr:
return {Op.getOperand(0)};
case Instruction::Select:
return {Op.getOperand(1), Op.getOperand(2)};
case Instruction::Call: {
const IntrinsicInst &II = cast<IntrinsicInst>(Op);
assert(II.getIntrinsicID() == Intrinsic::ptrmask &&
"unexpected intrinsic call");
return {II.getArgOperand(0)};
}
case Instruction::IntToPtr: {
assert(isNoopPtrIntCastPair(&Op, DL, TTI));
auto *P2I = cast<Operator>(Op.getOperand(0));
return {P2I->getOperand(0)};
}
default:
llvm_unreachable("Unexpected instruction type.");
}
}
bool InferAddressSpacesImpl::rewriteIntrinsicOperands(IntrinsicInst *II,
Value *OldV,
Value *NewV) const {
Module *M = II->getParent()->getParent()->getParent();
Intrinsic::ID IID = II->getIntrinsicID();
switch (IID) {
case Intrinsic::objectsize:
case Intrinsic::masked_load: {
Type *DestTy = II->getType();
Type *SrcTy = NewV->getType();
Function *NewDecl =
Intrinsic::getOrInsertDeclaration(M, IID, {DestTy, SrcTy});
II->setArgOperand(0, NewV);
II->setCalledFunction(NewDecl);
return true;
}
case Intrinsic::ptrmask:
// This is handled as an address expression, not as a use memory operation.
return false;
case Intrinsic::masked_gather: {
Type *RetTy = II->getType();
Type *NewPtrTy = NewV->getType();
Function *NewDecl =
Intrinsic::getOrInsertDeclaration(M, IID, {RetTy, NewPtrTy});
II->setArgOperand(0, NewV);
II->setCalledFunction(NewDecl);
return true;
}
case Intrinsic::masked_store:
case Intrinsic::masked_scatter: {
Type *ValueTy = II->getOperand(0)->getType();
Type *NewPtrTy = NewV->getType();
Function *NewDecl = Intrinsic::getOrInsertDeclaration(
M, II->getIntrinsicID(), {ValueTy, NewPtrTy});
II->setArgOperand(1, NewV);
II->setCalledFunction(NewDecl);
return true;
}
case Intrinsic::prefetch:
case Intrinsic::is_constant: {
Function *NewDecl = Intrinsic::getOrInsertDeclaration(
M, II->getIntrinsicID(), {NewV->getType()});
II->setArgOperand(0, NewV);
II->setCalledFunction(NewDecl);
return true;
}
case Intrinsic::fake_use: {
II->replaceUsesOfWith(OldV, NewV);
return true;
}
default: {
Value *Rewrite = TTI->rewriteIntrinsicWithAddressSpace(II, OldV, NewV);
if (!Rewrite)
return false;
if (Rewrite != II)
II->replaceAllUsesWith(Rewrite);
return true;
}
}
}
void InferAddressSpacesImpl::collectRewritableIntrinsicOperands(
IntrinsicInst *II, PostorderStackTy &PostorderStack,
DenseSet<Value *> &Visited) const {
auto IID = II->getIntrinsicID();
switch (IID) {
case Intrinsic::ptrmask:
case Intrinsic::objectsize:
appendsFlatAddressExpressionToPostorderStack(II->getArgOperand(0),
PostorderStack, Visited);
break;
case Intrinsic::is_constant: {
Value *Ptr = II->getArgOperand(0);
if (Ptr->getType()->isPtrOrPtrVectorTy()) {
appendsFlatAddressExpressionToPostorderStack(Ptr, PostorderStack,
Visited);
}
break;
}
case Intrinsic::masked_load:
case Intrinsic::masked_gather:
case Intrinsic::prefetch:
appendsFlatAddressExpressionToPostorderStack(II->getArgOperand(0),
PostorderStack, Visited);
break;
case Intrinsic::masked_store:
case Intrinsic::masked_scatter:
appendsFlatAddressExpressionToPostorderStack(II->getArgOperand(1),
PostorderStack, Visited);
break;
case Intrinsic::fake_use: {
for (Value *Op : II->operands()) {
if (Op->getType()->isPtrOrPtrVectorTy()) {
appendsFlatAddressExpressionToPostorderStack(Op, PostorderStack,
Visited);
}
}
break;
}
default:
SmallVector<int, 2> OpIndexes;
if (TTI->collectFlatAddressOperands(OpIndexes, IID)) {
for (int Idx : OpIndexes) {
appendsFlatAddressExpressionToPostorderStack(II->getArgOperand(Idx),
PostorderStack, Visited);
}
}
break;
}
}
// Returns all flat address expressions in function F. The elements are
// If V is an unvisited flat address expression, appends V to PostorderStack
// and marks it as visited.
void InferAddressSpacesImpl::appendsFlatAddressExpressionToPostorderStack(
Value *V, PostorderStackTy &PostorderStack,
DenseSet<Value *> &Visited) const {
assert(V->getType()->isPtrOrPtrVectorTy());
// Generic addressing expressions may be hidden in nested constant
// expressions.
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
// TODO: Look in non-address parts, like icmp operands.
if (isAddressExpression(*CE, *DL, TTI) && Visited.insert(CE).second)
PostorderStack.emplace_back(CE, false);
return;
}
if (V->getType()->getPointerAddressSpace() == FlatAddrSpace &&
isAddressExpression(*V, *DL, TTI)) {
if (Visited.insert(V).second) {
PostorderStack.emplace_back(V, false);
Operator *Op = cast<Operator>(V);
for (unsigned I = 0, E = Op->getNumOperands(); I != E; ++I) {
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Op->getOperand(I))) {
if (isAddressExpression(*CE, *DL, TTI) && Visited.insert(CE).second)
PostorderStack.emplace_back(CE, false);
}
}
}
}
}
// Returns all flat address expressions in function F. The elements are ordered
// in postorder.
std::vector<WeakTrackingVH>
InferAddressSpacesImpl::collectFlatAddressExpressions(Function &F) const {
// This function implements a non-recursive postorder traversal of a partial
// use-def graph of function F.
PostorderStackTy PostorderStack;
// The set of visited expressions.
DenseSet<Value *> Visited;
auto PushPtrOperand = [&](Value *Ptr) {
appendsFlatAddressExpressionToPostorderStack(Ptr, PostorderStack, Visited);
};
// Look at operations that may be interesting accelerate by moving to a known
// address space. We aim at generating after loads and stores, but pure
// addressing calculations may also be faster.
for (Instruction &I : instructions(F)) {
if (auto *GEP = dyn_cast<GetElementPtrInst>(&I)) {
PushPtrOperand(GEP->getPointerOperand());
} else if (auto *LI = dyn_cast<LoadInst>(&I))
PushPtrOperand(LI->getPointerOperand());
else if (auto *SI = dyn_cast<StoreInst>(&I))
PushPtrOperand(SI->getPointerOperand());
else if (auto *RMW = dyn_cast<AtomicRMWInst>(&I))
PushPtrOperand(RMW->getPointerOperand());
else if (auto *CmpX = dyn_cast<AtomicCmpXchgInst>(&I))
PushPtrOperand(CmpX->getPointerOperand());
else if (auto *MI = dyn_cast<MemIntrinsic>(&I)) {
// For memset/memcpy/memmove, any pointer operand can be replaced.
PushPtrOperand(MI->getRawDest());
// Handle 2nd operand for memcpy/memmove.
if (auto *MTI = dyn_cast<MemTransferInst>(MI))
PushPtrOperand(MTI->getRawSource());
} else if (auto *II = dyn_cast<IntrinsicInst>(&I))
collectRewritableIntrinsicOperands(II, PostorderStack, Visited);
else if (ICmpInst *Cmp = dyn_cast<ICmpInst>(&I)) {
if (Cmp->getOperand(0)->getType()->isPtrOrPtrVectorTy()) {
PushPtrOperand(Cmp->getOperand(0));
PushPtrOperand(Cmp->getOperand(1));
}
} else if (auto *ASC = dyn_cast<AddrSpaceCastInst>(&I)) {
PushPtrOperand(ASC->getPointerOperand());
} else if (auto *I2P = dyn_cast<IntToPtrInst>(&I)) {
if (isNoopPtrIntCastPair(cast<Operator>(I2P), *DL, TTI))
PushPtrOperand(cast<Operator>(I2P->getOperand(0))->getOperand(0));
} else if (auto *RI = dyn_cast<ReturnInst>(&I)) {
if (auto *RV = RI->getReturnValue();
RV && RV->getType()->isPtrOrPtrVectorTy())
PushPtrOperand(RV);
}
}
std::vector<WeakTrackingVH> Postorder; // The resultant postorder.
while (!PostorderStack.empty()) {
Value *TopVal = PostorderStack.back().getPointer();
// If the operands of the expression on the top are already explored,
// adds that expression to the resultant postorder.
if (PostorderStack.back().getInt()) {
if (TopVal->getType()->getPointerAddressSpace() == FlatAddrSpace)
Postorder.push_back(TopVal);
PostorderStack.pop_back();
continue;
}
// Otherwise, adds its operands to the stack and explores them.
PostorderStack.back().setInt(true);
// Skip values with an assumed address space.
if (TTI->getAssumedAddrSpace(TopVal) == UninitializedAddressSpace) {
for (Value *PtrOperand : getPointerOperands(*TopVal, *DL, TTI)) {
appendsFlatAddressExpressionToPostorderStack(PtrOperand, PostorderStack,
Visited);
}
}
}
return Postorder;
}
// A helper function for cloneInstructionWithNewAddressSpace. Returns the clone
// of OperandUse.get() in the new address space. If the clone is not ready yet,
// returns poison in the new address space as a placeholder.
static Value *operandWithNewAddressSpaceOrCreatePoison(
const Use &OperandUse, unsigned NewAddrSpace,
const ValueToValueMapTy &ValueWithNewAddrSpace,
const PredicatedAddrSpaceMapTy &PredicatedAS,
SmallVectorImpl<const Use *> *PoisonUsesToFix) {
Value *Operand = OperandUse.get();
Type *NewPtrTy = getPtrOrVecOfPtrsWithNewAS(Operand->getType(), NewAddrSpace);
if (Constant *C = dyn_cast<Constant>(Operand))
return ConstantExpr::getAddrSpaceCast(C, NewPtrTy);
if (Value *NewOperand = ValueWithNewAddrSpace.lookup(Operand))
return NewOperand;
Instruction *Inst = cast<Instruction>(OperandUse.getUser());
auto I = PredicatedAS.find(std::make_pair(Inst, Operand));
if (I != PredicatedAS.end()) {
// Insert an addrspacecast on that operand before the user.
unsigned NewAS = I->second;
Type *NewPtrTy = getPtrOrVecOfPtrsWithNewAS(Operand->getType(), NewAS);
auto *NewI = new AddrSpaceCastInst(Operand, NewPtrTy);
NewI->insertBefore(Inst->getIterator());
NewI->setDebugLoc(Inst->getDebugLoc());
return NewI;
}
PoisonUsesToFix->push_back(&OperandUse);
return PoisonValue::get(NewPtrTy);
}
// Returns a clone of `I` with its operands converted to those specified in
// ValueWithNewAddrSpace. Due to potential cycles in the data flow graph, an
// operand whose address space needs to be modified might not exist in
// ValueWithNewAddrSpace. In that case, uses poison as a placeholder operand and
// adds that operand use to PoisonUsesToFix so that caller can fix them later.
//
// Note that we do not necessarily clone `I`, e.g., if it is an addrspacecast
// from a pointer whose type already matches. Therefore, this function returns a
// Value* instead of an Instruction*.
//
// This may also return nullptr in the case the instruction could not be
// rewritten.
Value *InferAddressSpacesImpl::cloneInstructionWithNewAddressSpace(
Instruction *I, unsigned NewAddrSpace,
const ValueToValueMapTy &ValueWithNewAddrSpace,
const PredicatedAddrSpaceMapTy &PredicatedAS,
SmallVectorImpl<const Use *> *PoisonUsesToFix) const {
Type *NewPtrType = getPtrOrVecOfPtrsWithNewAS(I->getType(), NewAddrSpace);
if (I->getOpcode() == Instruction::AddrSpaceCast) {
Value *Src = I->getOperand(0);
// Because `I` is flat, the source address space must be specific.
// Therefore, the inferred address space must be the source space, according
// to our algorithm.
assert(Src->getType()->getPointerAddressSpace() == NewAddrSpace);
if (Src->getType() != NewPtrType)
return new BitCastInst(Src, NewPtrType);
return Src;
}
if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) {
// Technically the intrinsic ID is a pointer typed argument, so specially
// handle calls early.
assert(II->getIntrinsicID() == Intrinsic::ptrmask);
Value *NewPtr = operandWithNewAddressSpaceOrCreatePoison(
II->getArgOperandUse(0), NewAddrSpace, ValueWithNewAddrSpace,
PredicatedAS, PoisonUsesToFix);
Value *Rewrite =
TTI->rewriteIntrinsicWithAddressSpace(II, II->getArgOperand(0), NewPtr);
if (Rewrite) {
assert(Rewrite != II && "cannot modify this pointer operation in place");
return Rewrite;
}
return nullptr;
}
unsigned AS = TTI->getAssumedAddrSpace(I);
if (AS != UninitializedAddressSpace) {
// For the assumed address space, insert an `addrspacecast` to make that
// explicit.
Type *NewPtrTy = getPtrOrVecOfPtrsWithNewAS(I->getType(), AS);
auto *NewI = new AddrSpaceCastInst(I, NewPtrTy);
NewI->insertAfter(I->getIterator());
NewI->setDebugLoc(I->getDebugLoc());
return NewI;
}
// Computes the converted pointer operands.
SmallVector<Value *, 4> NewPointerOperands;
for (const Use &OperandUse : I->operands()) {
if (!OperandUse.get()->getType()->isPtrOrPtrVectorTy())
NewPointerOperands.push_back(nullptr);
else
NewPointerOperands.push_back(operandWithNewAddressSpaceOrCreatePoison(
OperandUse, NewAddrSpace, ValueWithNewAddrSpace, PredicatedAS,
PoisonUsesToFix));
}
switch (I->getOpcode()) {
case Instruction::BitCast:
return new BitCastInst(NewPointerOperands[0], NewPtrType);
case Instruction::PHI: {
assert(I->getType()->isPtrOrPtrVectorTy());
PHINode *PHI = cast<PHINode>(I);
PHINode *NewPHI = PHINode::Create(NewPtrType, PHI->getNumIncomingValues());
for (unsigned Index = 0; Index < PHI->getNumIncomingValues(); ++Index) {
unsigned OperandNo = PHINode::getOperandNumForIncomingValue(Index);
NewPHI->addIncoming(NewPointerOperands[OperandNo],
PHI->getIncomingBlock(Index));
}
return NewPHI;
}
case Instruction::GetElementPtr: {
GetElementPtrInst *GEP = cast<GetElementPtrInst>(I);
GetElementPtrInst *NewGEP = GetElementPtrInst::Create(
GEP->getSourceElementType(), NewPointerOperands[0],
SmallVector<Value *, 4>(GEP->indices()));
NewGEP->setIsInBounds(GEP->isInBounds());
return NewGEP;
}
case Instruction::Select:
assert(I->getType()->isPtrOrPtrVectorTy());
return SelectInst::Create(I->getOperand(0), NewPointerOperands[1],
NewPointerOperands[2], "", nullptr, I);
case Instruction::IntToPtr: {
assert(isNoopPtrIntCastPair(cast<Operator>(I), *DL, TTI));
Value *Src = cast<Operator>(I->getOperand(0))->getOperand(0);
if (Src->getType() == NewPtrType)
return Src;
// If we had a no-op inttoptr/ptrtoint pair, we may still have inferred a
// source address space from a generic pointer source need to insert a cast
// back.
return CastInst::CreatePointerBitCastOrAddrSpaceCast(Src, NewPtrType);
}
default:
llvm_unreachable("Unexpected opcode");
}
}
// Similar to cloneInstructionWithNewAddressSpace, returns a clone of the
// constant expression `CE` with its operands replaced as specified in
// ValueWithNewAddrSpace.
static Value *cloneConstantExprWithNewAddressSpace(
ConstantExpr *CE, unsigned NewAddrSpace,
const ValueToValueMapTy &ValueWithNewAddrSpace, const DataLayout *DL,
const TargetTransformInfo *TTI) {
Type *TargetType =
CE->getType()->isPtrOrPtrVectorTy()
? getPtrOrVecOfPtrsWithNewAS(CE->getType(), NewAddrSpace)
: CE->getType();
if (CE->getOpcode() == Instruction::AddrSpaceCast) {
// Because CE is flat, the source address space must be specific.
// Therefore, the inferred address space must be the source space according
// to our algorithm.
assert(CE->getOperand(0)->getType()->getPointerAddressSpace() ==
NewAddrSpace);
return ConstantExpr::getBitCast(CE->getOperand(0), TargetType);
}
if (CE->getOpcode() == Instruction::BitCast) {
if (Value *NewOperand = ValueWithNewAddrSpace.lookup(CE->getOperand(0)))
return ConstantExpr::getBitCast(cast<Constant>(NewOperand), TargetType);
return ConstantExpr::getAddrSpaceCast(CE, TargetType);
}
if (CE->getOpcode() == Instruction::IntToPtr) {
assert(isNoopPtrIntCastPair(cast<Operator>(CE), *DL, TTI));
Constant *Src = cast<ConstantExpr>(CE->getOperand(0))->getOperand(0);
assert(Src->getType()->getPointerAddressSpace() == NewAddrSpace);
return ConstantExpr::getBitCast(Src, TargetType);
}
// Computes the operands of the new constant expression.
bool IsNew = false;
SmallVector<Constant *, 4> NewOperands;
for (unsigned Index = 0; Index < CE->getNumOperands(); ++Index) {
Constant *Operand = CE->getOperand(Index);
// If the address space of `Operand` needs to be modified, the new operand
// with the new address space should already be in ValueWithNewAddrSpace
// because (1) the constant expressions we consider (i.e. addrspacecast,
// bitcast, and getelementptr) do not incur cycles in the data flow graph
// and (2) this function is called on constant expressions in postorder.
if (Value *NewOperand = ValueWithNewAddrSpace.lookup(Operand)) {
IsNew = true;
NewOperands.push_back(cast<Constant>(NewOperand));
continue;
}
if (auto *CExpr = dyn_cast<ConstantExpr>(Operand))
if (Value *NewOperand = cloneConstantExprWithNewAddressSpace(
CExpr, NewAddrSpace, ValueWithNewAddrSpace, DL, TTI)) {
IsNew = true;
NewOperands.push_back(cast<Constant>(NewOperand));
continue;
}
// Otherwise, reuses the old operand.
NewOperands.push_back(Operand);
}
// If !IsNew, we will replace the Value with itself. However, replaced values
// are assumed to wrapped in an addrspacecast cast later so drop it now.
if (!IsNew)
return nullptr;
if (CE->getOpcode() == Instruction::GetElementPtr) {
// Needs to specify the source type while constructing a getelementptr
// constant expression.
return CE->getWithOperands(NewOperands, TargetType, /*OnlyIfReduced=*/false,
cast<GEPOperator>(CE)->getSourceElementType());
}
return CE->getWithOperands(NewOperands, TargetType);
}
// Returns a clone of the value `V`, with its operands replaced as specified in
// ValueWithNewAddrSpace. This function is called on every flat address
// expression whose address space needs to be modified, in postorder.
//
// See cloneInstructionWithNewAddressSpace for the meaning of PoisonUsesToFix.
Value *InferAddressSpacesImpl::cloneValueWithNewAddressSpace(
Value *V, unsigned NewAddrSpace,
const ValueToValueMapTy &ValueWithNewAddrSpace,
const PredicatedAddrSpaceMapTy &PredicatedAS,
SmallVectorImpl<const Use *> *PoisonUsesToFix) const {
// All values in Postorder are flat address expressions.
assert(V->getType()->getPointerAddressSpace() == FlatAddrSpace &&
isAddressExpression(*V, *DL, TTI));
if (Instruction *I = dyn_cast<Instruction>(V)) {
Value *NewV = cloneInstructionWithNewAddressSpace(
I, NewAddrSpace, ValueWithNewAddrSpace, PredicatedAS, PoisonUsesToFix);
if (Instruction *NewI = dyn_cast_or_null<Instruction>(NewV)) {
if (NewI->getParent() == nullptr) {
NewI->insertBefore(I->getIterator());
NewI->takeName(I);
NewI->setDebugLoc(I->getDebugLoc());
}
}
return NewV;
}
return cloneConstantExprWithNewAddressSpace(
cast<ConstantExpr>(V), NewAddrSpace, ValueWithNewAddrSpace, DL, TTI);
}
// Defines the join operation on the address space lattice (see the file header
// comments).
unsigned InferAddressSpacesImpl::joinAddressSpaces(unsigned AS1,
unsigned AS2) const {
if (AS1 == FlatAddrSpace || AS2 == FlatAddrSpace)
return FlatAddrSpace;
if (AS1 == UninitializedAddressSpace)
return AS2;
if (AS2 == UninitializedAddressSpace)
return AS1;
// The join of two different specific address spaces is flat.
return (AS1 == AS2) ? AS1 : FlatAddrSpace;
}
bool InferAddressSpacesImpl::run(Function &CurFn) {
F = &CurFn;
DL = &F->getDataLayout();
if (AssumeDefaultIsFlatAddressSpace)
FlatAddrSpace = 0;
if (FlatAddrSpace == UninitializedAddressSpace) {
FlatAddrSpace = TTI->getFlatAddressSpace();
if (FlatAddrSpace == UninitializedAddressSpace)
return false;
}
// Collects all flat address expressions in postorder.
std::vector<WeakTrackingVH> Postorder = collectFlatAddressExpressions(*F);
// Runs a data-flow analysis to refine the address spaces of every expression
// in Postorder.
ValueToAddrSpaceMapTy InferredAddrSpace;
PredicatedAddrSpaceMapTy PredicatedAS;
inferAddressSpaces(Postorder, InferredAddrSpace, PredicatedAS);
// Changes the address spaces of the flat address expressions who are inferred
// to point to a specific address space.
return rewriteWithNewAddressSpaces(Postorder, InferredAddrSpace,
PredicatedAS);
}
// Constants need to be tracked through RAUW to handle cases with nested
// constant expressions, so wrap values in WeakTrackingVH.
void InferAddressSpacesImpl::inferAddressSpaces(
ArrayRef<WeakTrackingVH> Postorder,
ValueToAddrSpaceMapTy &InferredAddrSpace,
PredicatedAddrSpaceMapTy &PredicatedAS) const {
SetVector<Value *> Worklist(Postorder.begin(), Postorder.end());
// Initially, all expressions are in the uninitialized address space.
for (Value *V : Postorder)
InferredAddrSpace[V] = UninitializedAddressSpace;
while (!Worklist.empty()) {
Value *V = Worklist.pop_back_val();
// Try to update the address space of the stack top according to the
// address spaces of its operands.
if (!updateAddressSpace(*V, InferredAddrSpace, PredicatedAS))
continue;
for (Value *User : V->users()) {
// Skip if User is already in the worklist.
if (Worklist.count(User))
continue;
auto Pos = InferredAddrSpace.find(User);
// Our algorithm only updates the address spaces of flat address
// expressions, which are those in InferredAddrSpace.
if (Pos == InferredAddrSpace.end())
continue;
// Function updateAddressSpace moves the address space down a lattice
// path. Therefore, nothing to do if User is already inferred as flat (the
// bottom element in the lattice).
if (Pos->second == FlatAddrSpace)
continue;
Worklist.insert(User);
}
}
}
unsigned
InferAddressSpacesImpl::getPredicatedAddrSpace(const Value &Ptr,
const Value *UserCtx) const {
const Instruction *UserCtxI = dyn_cast<Instruction>(UserCtx);
if (!UserCtxI)
return UninitializedAddressSpace;
const Value *StrippedPtr = Ptr.stripInBoundsOffsets();
for (auto &AssumeVH : AC.assumptionsFor(StrippedPtr)) {
if (!AssumeVH)
continue;
CallInst *CI = cast<CallInst>(AssumeVH);
if (!isValidAssumeForContext(CI, UserCtxI, DT))
continue;
const Value *Ptr;
unsigned AS;
std::tie(Ptr, AS) = TTI->getPredicatedAddrSpace(CI->getArgOperand(0));
if (Ptr)
return AS;
}
return UninitializedAddressSpace;
}
bool InferAddressSpacesImpl::updateAddressSpace(
const Value &V, ValueToAddrSpaceMapTy &InferredAddrSpace,
PredicatedAddrSpaceMapTy &PredicatedAS) const {
assert(InferredAddrSpace.count(&V));
LLVM_DEBUG(dbgs() << "Updating the address space of\n " << V << '\n');
// The new inferred address space equals the join of the address spaces
// of all its pointer operands.
unsigned NewAS = UninitializedAddressSpace;
const Operator &Op = cast<Operator>(V);
if (Op.getOpcode() == Instruction::Select) {
Value *Src0 = Op.getOperand(1);
Value *Src1 = Op.getOperand(2);
auto I = InferredAddrSpace.find(Src0);
unsigned Src0AS = (I != InferredAddrSpace.end())
? I->second
: Src0->getType()->getPointerAddressSpace();
auto J = InferredAddrSpace.find(Src1);
unsigned Src1AS = (J != InferredAddrSpace.end())
? J->second
: Src1->getType()->getPointerAddressSpace();
auto *C0 = dyn_cast<Constant>(Src0);
auto *C1 = dyn_cast<Constant>(Src1);
// If one of the inputs is a constant, we may be able to do a constant
// addrspacecast of it. Defer inferring the address space until the input
// address space is known.
if ((C1 && Src0AS == UninitializedAddressSpace) ||
(C0 && Src1AS == UninitializedAddressSpace))
return false;
if (C0 && isSafeToCastConstAddrSpace(C0, Src1AS))
NewAS = Src1AS;
else if (C1 && isSafeToCastConstAddrSpace(C1, Src0AS))
NewAS = Src0AS;
else
NewAS = joinAddressSpaces(Src0AS, Src1AS);
} else {
unsigned AS = TTI->getAssumedAddrSpace(&V);
if (AS != UninitializedAddressSpace) {
// Use the assumed address space directly.
NewAS = AS;
} else {
// Otherwise, infer the address space from its pointer operands.
for (Value *PtrOperand : getPointerOperands(V, *DL, TTI)) {
auto I = InferredAddrSpace.find(PtrOperand);
unsigned OperandAS;
if (I == InferredAddrSpace.end()) {
OperandAS = PtrOperand->getType()->getPointerAddressSpace();
if (OperandAS == FlatAddrSpace) {
// Check AC for assumption dominating V.
unsigned AS = getPredicatedAddrSpace(*PtrOperand, &V);
if (AS != UninitializedAddressSpace) {
LLVM_DEBUG(dbgs()
<< " deduce operand AS from the predicate addrspace "
<< AS << '\n');
OperandAS = AS;
// Record this use with the predicated AS.
PredicatedAS[std::make_pair(&V, PtrOperand)] = OperandAS;
}
}
} else
OperandAS = I->second;
// join(flat, *) = flat. So we can break if NewAS is already flat.
NewAS = joinAddressSpaces(NewAS, OperandAS);
if (NewAS == FlatAddrSpace)
break;
}
}
}
unsigned OldAS = InferredAddrSpace.lookup(&V);
assert(OldAS != FlatAddrSpace);
if (OldAS == NewAS)
return false;
// If any updates are made, grabs its users to the worklist because
// their address spaces can also be possibly updated.
LLVM_DEBUG(dbgs() << " to " << NewAS << '\n');
InferredAddrSpace[&V] = NewAS;
return true;
}
/// Replace operand \p OpIdx in \p Inst, if the value is the same as \p OldVal
/// with \p NewVal.
static bool replaceOperandIfSame(Instruction *Inst, unsigned OpIdx,
Value *OldVal, Value *NewVal) {
Use &U = Inst->getOperandUse(OpIdx);
if (U.get() == OldVal) {
U.set(NewVal);
return true;
}
return false;
}
template <typename InstrType>
static bool replaceSimplePointerUse(const TargetTransformInfo &TTI,
InstrType *MemInstr, unsigned AddrSpace,
Value *OldV, Value *NewV) {
if (!MemInstr->isVolatile() || TTI.hasVolatileVariant(MemInstr, AddrSpace)) {
return replaceOperandIfSame(MemInstr, InstrType::getPointerOperandIndex(),
OldV, NewV);
}
return false;
}
/// If \p OldV is used as the pointer operand of a compatible memory operation
/// \p Inst, replaces the pointer operand with NewV.
///
/// This covers memory instructions with a single pointer operand that can have
/// its address space changed by simply mutating the use to a new value.
///
/// \p returns true the user replacement was made.
static bool replaceIfSimplePointerUse(const TargetTransformInfo &TTI,
User *Inst, unsigned AddrSpace,
Value *OldV, Value *NewV) {
if (auto *LI = dyn_cast<LoadInst>(Inst))
return replaceSimplePointerUse(TTI, LI, AddrSpace, OldV, NewV);
if (auto *SI = dyn_cast<StoreInst>(Inst))
return replaceSimplePointerUse(TTI, SI, AddrSpace, OldV, NewV);
if (auto *RMW = dyn_cast<AtomicRMWInst>(Inst))
return replaceSimplePointerUse(TTI, RMW, AddrSpace, OldV, NewV);
if (auto *CmpX = dyn_cast<AtomicCmpXchgInst>(Inst))
return replaceSimplePointerUse(TTI, CmpX, AddrSpace, OldV, NewV);
return false;
}
/// Update memory intrinsic uses that require more complex processing than
/// simple memory instructions. These require re-mangling and may have multiple
/// pointer operands.
static bool handleMemIntrinsicPtrUse(MemIntrinsic *MI, Value *OldV,
Value *NewV) {
IRBuilder<> B(MI);
MDNode *TBAA = MI->getMetadata(LLVMContext::MD_tbaa);
MDNode *ScopeMD = MI->getMetadata(LLVMContext::MD_alias_scope);
MDNode *NoAliasMD = MI->getMetadata(LLVMContext::MD_noalias);
if (auto *MSI = dyn_cast<MemSetInst>(MI)) {
B.CreateMemSet(NewV, MSI->getValue(), MSI->getLength(), MSI->getDestAlign(),
false, // isVolatile
TBAA, ScopeMD, NoAliasMD);
} else if (auto *MTI = dyn_cast<MemTransferInst>(MI)) {
Value *Src = MTI->getRawSource();
Value *Dest = MTI->getRawDest();
// Be careful in case this is a self-to-self copy.
if (Src == OldV)
Src = NewV;
if (Dest == OldV)
Dest = NewV;
if (isa<MemCpyInlineInst>(MTI)) {
MDNode *TBAAStruct = MTI->getMetadata(LLVMContext::MD_tbaa_struct);
B.CreateMemCpyInline(Dest, MTI->getDestAlign(), Src,
MTI->getSourceAlign(), MTI->getLength(),
false, // isVolatile
TBAA, TBAAStruct, ScopeMD, NoAliasMD);
} else if (isa<MemCpyInst>(MTI)) {
MDNode *TBAAStruct = MTI->getMetadata(LLVMContext::MD_tbaa_struct);
B.CreateMemCpy(Dest, MTI->getDestAlign(), Src, MTI->getSourceAlign(),
MTI->getLength(),
false, // isVolatile
TBAA, TBAAStruct, ScopeMD, NoAliasMD);
} else {
assert(isa<MemMoveInst>(MTI));
B.CreateMemMove(Dest, MTI->getDestAlign(), Src, MTI->getSourceAlign(),
MTI->getLength(),
false, // isVolatile
TBAA, ScopeMD, NoAliasMD);
}
} else
llvm_unreachable("unhandled MemIntrinsic");
MI->eraseFromParent();
return true;
}
// \p returns true if it is OK to change the address space of constant \p C with
// a ConstantExpr addrspacecast.
bool InferAddressSpacesImpl::isSafeToCastConstAddrSpace(Constant *C,
unsigned NewAS) const {
assert(NewAS != UninitializedAddressSpace);
unsigned SrcAS = C->getType()->getPointerAddressSpace();
if (SrcAS == NewAS || isa<UndefValue>(C))
return true;
// Prevent illegal casts between different non-flat address spaces.
if (SrcAS != FlatAddrSpace && NewAS != FlatAddrSpace)
return false;
if (isa<ConstantPointerNull>(C))
return true;
if (auto *Op = dyn_cast<Operator>(C)) {
// If we already have a constant addrspacecast, it should be safe to cast it
// off.
if (Op->getOpcode() == Instruction::AddrSpaceCast)
return isSafeToCastConstAddrSpace(cast<Constant>(Op->getOperand(0)),
NewAS);
if (Op->getOpcode() == Instruction::IntToPtr &&
Op->getType()->getPointerAddressSpace() == FlatAddrSpace)
return true;
}
return false;
}
static Value::use_iterator skipToNextUser(Value::use_iterator I,
Value::use_iterator End) {
User *CurUser = I->getUser();
++I;
while (I != End && I->getUser() == CurUser)
++I;
return I;
}
void InferAddressSpacesImpl::performPointerReplacement(
Value *V, Value *NewV, Use &U, ValueToValueMapTy &ValueWithNewAddrSpace,
SmallVectorImpl<Instruction *> &DeadInstructions) const {
User *CurUser = U.getUser();
unsigned AddrSpace = V->getType()->getPointerAddressSpace();
if (replaceIfSimplePointerUse(*TTI, CurUser, AddrSpace, V, NewV))
return;
// Skip if the current user is the new value itself.
if (CurUser == NewV)
return;
auto *CurUserI = dyn_cast<Instruction>(CurUser);
if (!CurUserI || CurUserI->getFunction() != F)
return;
// Handle more complex cases like intrinsic that need to be remangled.
if (auto *MI = dyn_cast<MemIntrinsic>(CurUser)) {
if (!MI->isVolatile() && handleMemIntrinsicPtrUse(MI, V, NewV))
return;
}
if (auto *II = dyn_cast<IntrinsicInst>(CurUser)) {
if (rewriteIntrinsicOperands(II, V, NewV))
return;
}
if (ICmpInst *Cmp = dyn_cast<ICmpInst>(CurUserI)) {
// If we can infer that both pointers are in the same addrspace,
// transform e.g.
// %cmp = icmp eq float* %p, %q
// into
// %cmp = icmp eq float addrspace(3)* %new_p, %new_q
unsigned NewAS = NewV->getType()->getPointerAddressSpace();
int SrcIdx = U.getOperandNo();
int OtherIdx = (SrcIdx == 0) ? 1 : 0;
Value *OtherSrc = Cmp->getOperand(OtherIdx);
if (Value *OtherNewV = ValueWithNewAddrSpace.lookup(OtherSrc)) {
if (OtherNewV->getType()->getPointerAddressSpace() == NewAS) {
Cmp->setOperand(OtherIdx, OtherNewV);
Cmp->setOperand(SrcIdx, NewV);
return;
}
}
// Even if the type mismatches, we can cast the constant.
if (auto *KOtherSrc = dyn_cast<Constant>(OtherSrc)) {
if (isSafeToCastConstAddrSpace(KOtherSrc, NewAS)) {
Cmp->setOperand(SrcIdx, NewV);
Cmp->setOperand(OtherIdx, ConstantExpr::getAddrSpaceCast(
KOtherSrc, NewV->getType()));
return;
}
}
}
if (AddrSpaceCastInst *ASC = dyn_cast<AddrSpaceCastInst>(CurUserI)) {
unsigned NewAS = NewV->getType()->getPointerAddressSpace();
if (ASC->getDestAddressSpace() == NewAS) {
ASC->replaceAllUsesWith(NewV);
DeadInstructions.push_back(ASC);
return;
}
}
// Otherwise, replaces the use with flat(NewV).
if (Instruction *VInst = dyn_cast<Instruction>(V)) {
// Don't create a copy of the original addrspacecast.
if (U == V && isa<AddrSpaceCastInst>(V))
return;
// Insert the addrspacecast after NewV.
BasicBlock::iterator InsertPos;
if (Instruction *NewVInst = dyn_cast<Instruction>(NewV))
InsertPos = std::next(NewVInst->getIterator());
else
InsertPos = std::next(VInst->getIterator());
while (isa<PHINode>(InsertPos))
++InsertPos;
// This instruction may contain multiple uses of V, update them all.
CurUser->replaceUsesOfWith(
V, new AddrSpaceCastInst(NewV, V->getType(), "", InsertPos));
} else {
CurUserI->replaceUsesOfWith(
V, ConstantExpr::getAddrSpaceCast(cast<Constant>(NewV), V->getType()));
}
}
bool InferAddressSpacesImpl::rewriteWithNewAddressSpaces(
ArrayRef<WeakTrackingVH> Postorder,
const ValueToAddrSpaceMapTy &InferredAddrSpace,
const PredicatedAddrSpaceMapTy &PredicatedAS) const {
// For each address expression to be modified, creates a clone of it with its
// pointer operands converted to the new address space. Since the pointer
// operands are converted, the clone is naturally in the new address space by
// construction.
ValueToValueMapTy ValueWithNewAddrSpace;
SmallVector<const Use *, 32> PoisonUsesToFix;
for (Value *V : Postorder) {
unsigned NewAddrSpace = InferredAddrSpace.lookup(V);
// In some degenerate cases (e.g. invalid IR in unreachable code), we may
// not even infer the value to have its original address space.
if (NewAddrSpace == UninitializedAddressSpace)
continue;
if (V->getType()->getPointerAddressSpace() != NewAddrSpace) {
Value *New =
cloneValueWithNewAddressSpace(V, NewAddrSpace, ValueWithNewAddrSpace,
PredicatedAS, &PoisonUsesToFix);
if (New)
ValueWithNewAddrSpace[V] = New;
}
}
if (ValueWithNewAddrSpace.empty())
return false;
// Fixes all the poison uses generated by cloneInstructionWithNewAddressSpace.
for (const Use *PoisonUse : PoisonUsesToFix) {
User *V = PoisonUse->getUser();
User *NewV = cast_or_null<User>(ValueWithNewAddrSpace.lookup(V));
if (!NewV)
continue;
unsigned OperandNo = PoisonUse->getOperandNo();
assert(isa<PoisonValue>(NewV->getOperand(OperandNo)));
NewV->setOperand(OperandNo, ValueWithNewAddrSpace.lookup(PoisonUse->get()));
}
SmallVector<Instruction *, 16> DeadInstructions;
ValueToValueMapTy VMap;
ValueMapper VMapper(VMap, RF_NoModuleLevelChanges | RF_IgnoreMissingLocals);
// Replaces the uses of the old address expressions with the new ones.
for (const WeakTrackingVH &WVH : Postorder) {
assert(WVH && "value was unexpectedly deleted");
Value *V = WVH;
Value *NewV = ValueWithNewAddrSpace.lookup(V);
if (NewV == nullptr)
continue;
LLVM_DEBUG(dbgs() << "Replacing the uses of " << *V << "\n with\n "
<< *NewV << '\n');
if (Constant *C = dyn_cast<Constant>(V)) {
Constant *Replace =
ConstantExpr::getAddrSpaceCast(cast<Constant>(NewV), C->getType());
if (C != Replace) {
LLVM_DEBUG(dbgs() << "Inserting replacement const cast: " << Replace
<< ": " << *Replace << '\n');
SmallVector<User *, 16> WorkList;
for (User *U : make_early_inc_range(C->users())) {
if (auto *I = dyn_cast<Instruction>(U)) {
if (I->getFunction() == F)
I->replaceUsesOfWith(C, Replace);
} else {
WorkList.append(U->user_begin(), U->user_end());
}
}
if (!WorkList.empty()) {
VMap[C] = Replace;
DenseSet<User *> Visited{WorkList.begin(), WorkList.end()};
while (!WorkList.empty()) {
User *U = WorkList.pop_back_val();
if (auto *I = dyn_cast<Instruction>(U)) {
if (I->getFunction() == F)
VMapper.remapInstruction(*I);
continue;
}
for (User *U2 : U->users())
if (Visited.insert(U2).second)
WorkList.push_back(U2);
}
}
V = Replace;
}
}
Value::use_iterator I, E, Next;
for (I = V->use_begin(), E = V->use_end(); I != E;) {
Use &U = *I;
// Some users may see the same pointer operand in multiple operands. Skip
// to the next instruction.
I = skipToNextUser(I, E);
performPointerReplacement(V, NewV, U, ValueWithNewAddrSpace,
DeadInstructions);
}
if (V->use_empty()) {
if (Instruction *I = dyn_cast<Instruction>(V))
DeadInstructions.push_back(I);
}
}
for (Instruction *I : DeadInstructions)
RecursivelyDeleteTriviallyDeadInstructions(I);
return true;
}
bool InferAddressSpaces::runOnFunction(Function &F) {
if (skipFunction(F))
return false;
auto *DTWP = getAnalysisIfAvailable<DominatorTreeWrapperPass>();
DominatorTree *DT = DTWP ? &DTWP->getDomTree() : nullptr;
return InferAddressSpacesImpl(
getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F), DT,
&getAnalysis<TargetTransformInfoWrapperPass>().getTTI(F),
FlatAddrSpace)
.run(F);
}
FunctionPass *llvm::createInferAddressSpacesPass(unsigned AddressSpace) {
return new InferAddressSpaces(AddressSpace);
}
InferAddressSpacesPass::InferAddressSpacesPass()
: FlatAddrSpace(UninitializedAddressSpace) {}
InferAddressSpacesPass::InferAddressSpacesPass(unsigned AddressSpace)
: FlatAddrSpace(AddressSpace) {}
PreservedAnalyses InferAddressSpacesPass::run(Function &F,
FunctionAnalysisManager &AM) {
bool Changed =
InferAddressSpacesImpl(AM.getResult<AssumptionAnalysis>(F),
AM.getCachedResult<DominatorTreeAnalysis>(F),
&AM.getResult<TargetIRAnalysis>(F), FlatAddrSpace)
.run(F);
if (Changed) {
PreservedAnalyses PA;
PA.preserveSet<CFGAnalyses>();
PA.preserve<DominatorTreeAnalysis>();
return PA;
}
return PreservedAnalyses::all();
}