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//===- ScalarizeMaskedMemIntrin.cpp - Scalarize unsupported masked mem ----===//
// instrinsics
//
// 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 pass replaces masked memory intrinsics - when unsupported by the target
// - with a chain of basic blocks, that deal with the elements one-by-one if the
// appropriate mask bit is set.
//
//===----------------------------------------------------------------------===//
#include "llvm/ADT/Twine.h"
#include "llvm/Analysis/TargetTransformInfo.h"
#include "llvm/CodeGen/TargetSubtargetInfo.h"
#include "llvm/IR/BasicBlock.h"
#include "llvm/IR/Constant.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/InstrTypes.h"
#include "llvm/IR/Instruction.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/Intrinsics.h"
#include "llvm/IR/Type.h"
#include "llvm/IR/Value.h"
#include "llvm/Pass.h"
#include "llvm/Support/Casting.h"
#include <algorithm>
#include <cassert>
using namespace llvm;
#define DEBUG_TYPE "scalarize-masked-mem-intrin"
namespace {
class ScalarizeMaskedMemIntrin : public FunctionPass {
const TargetTransformInfo *TTI = nullptr;
public:
static char ID; // Pass identification, replacement for typeid
explicit ScalarizeMaskedMemIntrin() : FunctionPass(ID) {
initializeScalarizeMaskedMemIntrinPass(*PassRegistry::getPassRegistry());
}
bool runOnFunction(Function &F) override;
StringRef getPassName() const override {
return "Scalarize Masked Memory Intrinsics";
}
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.addRequired<TargetTransformInfoWrapperPass>();
}
private:
bool optimizeBlock(BasicBlock &BB, bool &ModifiedDT);
bool optimizeCallInst(CallInst *CI, bool &ModifiedDT);
};
} // end anonymous namespace
char ScalarizeMaskedMemIntrin::ID = 0;
INITIALIZE_PASS(ScalarizeMaskedMemIntrin, DEBUG_TYPE,
"Scalarize unsupported masked memory intrinsics", false, false)
FunctionPass *llvm::createScalarizeMaskedMemIntrinPass() {
return new ScalarizeMaskedMemIntrin();
}
static bool isConstantIntVector(Value *Mask) {
Constant *C = dyn_cast<Constant>(Mask);
if (!C)
return false;
unsigned NumElts = Mask->getType()->getVectorNumElements();
for (unsigned i = 0; i != NumElts; ++i) {
Constant *CElt = C->getAggregateElement(i);
if (!CElt || !isa<ConstantInt>(CElt))
return false;
}
return true;
}
// Translate a masked load intrinsic like
// <16 x i32 > @llvm.masked.load( <16 x i32>* %addr, i32 align,
// <16 x i1> %mask, <16 x i32> %passthru)
// to a chain of basic blocks, with loading element one-by-one if
// the appropriate mask bit is set
//
// %1 = bitcast i8* %addr to i32*
// %2 = extractelement <16 x i1> %mask, i32 0
// br i1 %2, label %cond.load, label %else
//
// cond.load: ; preds = %0
// %3 = getelementptr i32* %1, i32 0
// %4 = load i32* %3
// %5 = insertelement <16 x i32> %passthru, i32 %4, i32 0
// br label %else
//
// else: ; preds = %0, %cond.load
// %res.phi.else = phi <16 x i32> [ %5, %cond.load ], [ undef, %0 ]
// %6 = extractelement <16 x i1> %mask, i32 1
// br i1 %6, label %cond.load1, label %else2
//
// cond.load1: ; preds = %else
// %7 = getelementptr i32* %1, i32 1
// %8 = load i32* %7
// %9 = insertelement <16 x i32> %res.phi.else, i32 %8, i32 1
// br label %else2
//
// else2: ; preds = %else, %cond.load1
// %res.phi.else3 = phi <16 x i32> [ %9, %cond.load1 ], [ %res.phi.else, %else ]
// %10 = extractelement <16 x i1> %mask, i32 2
// br i1 %10, label %cond.load4, label %else5
//
static void scalarizeMaskedLoad(CallInst *CI) {
Value *Ptr = CI->getArgOperand(0);
Value *Alignment = CI->getArgOperand(1);
Value *Mask = CI->getArgOperand(2);
Value *Src0 = CI->getArgOperand(3);
unsigned AlignVal = cast<ConstantInt>(Alignment)->getZExtValue();
VectorType *VecType = cast<VectorType>(CI->getType());
Type *EltTy = VecType->getElementType();
IRBuilder<> Builder(CI->getContext());
Instruction *InsertPt = CI;
BasicBlock *IfBlock = CI->getParent();
Builder.SetInsertPoint(InsertPt);
Builder.SetCurrentDebugLocation(CI->getDebugLoc());
// Short-cut if the mask is all-true.
if (isa<Constant>(Mask) && cast<Constant>(Mask)->isAllOnesValue()) {
Value *NewI = Builder.CreateAlignedLoad(VecType, Ptr, AlignVal);
CI->replaceAllUsesWith(NewI);
CI->eraseFromParent();
return;
}
// Adjust alignment for the scalar instruction.
AlignVal = MinAlign(AlignVal, EltTy->getPrimitiveSizeInBits() / 8);
// Bitcast %addr fron i8* to EltTy*
Type *NewPtrType =
EltTy->getPointerTo(cast<PointerType>(Ptr->getType())->getAddressSpace());
Value *FirstEltPtr = Builder.CreateBitCast(Ptr, NewPtrType);
unsigned VectorWidth = VecType->getNumElements();
// The result vector
Value *VResult = Src0;
if (isConstantIntVector(Mask)) {
for (unsigned Idx = 0; Idx < VectorWidth; ++Idx) {
if (cast<Constant>(Mask)->getAggregateElement(Idx)->isNullValue())
continue;
Value *Gep =
Builder.CreateInBoundsGEP(EltTy, FirstEltPtr, Builder.getInt32(Idx));
LoadInst *Load = Builder.CreateAlignedLoad(EltTy, Gep, AlignVal);
VResult =
Builder.CreateInsertElement(VResult, Load, Builder.getInt32(Idx));
}
CI->replaceAllUsesWith(VResult);
CI->eraseFromParent();
return;
}
for (unsigned Idx = 0; Idx < VectorWidth; ++Idx) {
// Fill the "else" block, created in the previous iteration
//
// %res.phi.else3 = phi <16 x i32> [ %11, %cond.load1 ], [ %res.phi.else, %else ]
// %mask_1 = extractelement <16 x i1> %mask, i32 Idx
// br i1 %mask_1, label %cond.load, label %else
//
Value *Predicate =
Builder.CreateExtractElement(Mask, Builder.getInt32(Idx));
// Create "cond" block
//
// %EltAddr = getelementptr i32* %1, i32 0
// %Elt = load i32* %EltAddr
// VResult = insertelement <16 x i32> VResult, i32 %Elt, i32 Idx
//
BasicBlock *CondBlock = IfBlock->splitBasicBlock(InsertPt->getIterator(),
"cond.load");
Builder.SetInsertPoint(InsertPt);
Value *Gep =
Builder.CreateInBoundsGEP(EltTy, FirstEltPtr, Builder.getInt32(Idx));
LoadInst *Load = Builder.CreateAlignedLoad(EltTy, Gep, AlignVal);
Value *NewVResult = Builder.CreateInsertElement(VResult, Load,
Builder.getInt32(Idx));
// Create "else" block, fill it in the next iteration
BasicBlock *NewIfBlock =
CondBlock->splitBasicBlock(InsertPt->getIterator(), "else");
Builder.SetInsertPoint(InsertPt);
Instruction *OldBr = IfBlock->getTerminator();
BranchInst::Create(CondBlock, NewIfBlock, Predicate, OldBr);
OldBr->eraseFromParent();
BasicBlock *PrevIfBlock = IfBlock;
IfBlock = NewIfBlock;
// Create the phi to join the new and previous value.
PHINode *Phi = Builder.CreatePHI(VecType, 2, "res.phi.else");
Phi->addIncoming(NewVResult, CondBlock);
Phi->addIncoming(VResult, PrevIfBlock);
VResult = Phi;
}
CI->replaceAllUsesWith(VResult);
CI->eraseFromParent();
}
// Translate a masked store intrinsic, like
// void @llvm.masked.store(<16 x i32> %src, <16 x i32>* %addr, i32 align,
// <16 x i1> %mask)
// to a chain of basic blocks, that stores element one-by-one if
// the appropriate mask bit is set
//
// %1 = bitcast i8* %addr to i32*
// %2 = extractelement <16 x i1> %mask, i32 0
// br i1 %2, label %cond.store, label %else
//
// cond.store: ; preds = %0
// %3 = extractelement <16 x i32> %val, i32 0
// %4 = getelementptr i32* %1, i32 0
// store i32 %3, i32* %4
// br label %else
//
// else: ; preds = %0, %cond.store
// %5 = extractelement <16 x i1> %mask, i32 1
// br i1 %5, label %cond.store1, label %else2
//
// cond.store1: ; preds = %else
// %6 = extractelement <16 x i32> %val, i32 1
// %7 = getelementptr i32* %1, i32 1
// store i32 %6, i32* %7
// br label %else2
// . . .
static void scalarizeMaskedStore(CallInst *CI) {
Value *Src = CI->getArgOperand(0);
Value *Ptr = CI->getArgOperand(1);
Value *Alignment = CI->getArgOperand(2);
Value *Mask = CI->getArgOperand(3);
unsigned AlignVal = cast<ConstantInt>(Alignment)->getZExtValue();
VectorType *VecType = cast<VectorType>(Src->getType());
Type *EltTy = VecType->getElementType();
IRBuilder<> Builder(CI->getContext());
Instruction *InsertPt = CI;
BasicBlock *IfBlock = CI->getParent();
Builder.SetInsertPoint(InsertPt);
Builder.SetCurrentDebugLocation(CI->getDebugLoc());
// Short-cut if the mask is all-true.
if (isa<Constant>(Mask) && cast<Constant>(Mask)->isAllOnesValue()) {
Builder.CreateAlignedStore(Src, Ptr, AlignVal);
CI->eraseFromParent();
return;
}
// Adjust alignment for the scalar instruction.
AlignVal = MinAlign(AlignVal, EltTy->getPrimitiveSizeInBits() / 8);
// Bitcast %addr fron i8* to EltTy*
Type *NewPtrType =
EltTy->getPointerTo(cast<PointerType>(Ptr->getType())->getAddressSpace());
Value *FirstEltPtr = Builder.CreateBitCast(Ptr, NewPtrType);
unsigned VectorWidth = VecType->getNumElements();
if (isConstantIntVector(Mask)) {
for (unsigned Idx = 0; Idx < VectorWidth; ++Idx) {
if (cast<Constant>(Mask)->getAggregateElement(Idx)->isNullValue())
continue;
Value *OneElt = Builder.CreateExtractElement(Src, Builder.getInt32(Idx));
Value *Gep =
Builder.CreateInBoundsGEP(EltTy, FirstEltPtr, Builder.getInt32(Idx));
Builder.CreateAlignedStore(OneElt, Gep, AlignVal);
}
CI->eraseFromParent();
return;
}
for (unsigned Idx = 0; Idx < VectorWidth; ++Idx) {
// Fill the "else" block, created in the previous iteration
//
// %mask_1 = extractelement <16 x i1> %mask, i32 Idx
// br i1 %mask_1, label %cond.store, label %else
//
Value *Predicate =
Builder.CreateExtractElement(Mask, Builder.getInt32(Idx));
// Create "cond" block
//
// %OneElt = extractelement <16 x i32> %Src, i32 Idx
// %EltAddr = getelementptr i32* %1, i32 0
// %store i32 %OneElt, i32* %EltAddr
//
BasicBlock *CondBlock =
IfBlock->splitBasicBlock(InsertPt->getIterator(), "cond.store");
Builder.SetInsertPoint(InsertPt);
Value *OneElt = Builder.CreateExtractElement(Src, Builder.getInt32(Idx));
Value *Gep =
Builder.CreateInBoundsGEP(EltTy, FirstEltPtr, Builder.getInt32(Idx));
Builder.CreateAlignedStore(OneElt, Gep, AlignVal);
// Create "else" block, fill it in the next iteration
BasicBlock *NewIfBlock =
CondBlock->splitBasicBlock(InsertPt->getIterator(), "else");
Builder.SetInsertPoint(InsertPt);
Instruction *OldBr = IfBlock->getTerminator();
BranchInst::Create(CondBlock, NewIfBlock, Predicate, OldBr);
OldBr->eraseFromParent();
IfBlock = NewIfBlock;
}
CI->eraseFromParent();
}
// Translate a masked gather intrinsic like
// <16 x i32 > @llvm.masked.gather.v16i32( <16 x i32*> %Ptrs, i32 4,
// <16 x i1> %Mask, <16 x i32> %Src)
// to a chain of basic blocks, with loading element one-by-one if
// the appropriate mask bit is set
//
// %Ptrs = getelementptr i32, i32* %base, <16 x i64> %ind
// %Mask0 = extractelement <16 x i1> %Mask, i32 0
// br i1 %Mask0, label %cond.load, label %else
//
// cond.load:
// %Ptr0 = extractelement <16 x i32*> %Ptrs, i32 0
// %Load0 = load i32, i32* %Ptr0, align 4
// %Res0 = insertelement <16 x i32> undef, i32 %Load0, i32 0
// br label %else
//
// else:
// %res.phi.else = phi <16 x i32>[%Res0, %cond.load], [undef, %0]
// %Mask1 = extractelement <16 x i1> %Mask, i32 1
// br i1 %Mask1, label %cond.load1, label %else2
//
// cond.load1:
// %Ptr1 = extractelement <16 x i32*> %Ptrs, i32 1
// %Load1 = load i32, i32* %Ptr1, align 4
// %Res1 = insertelement <16 x i32> %res.phi.else, i32 %Load1, i32 1
// br label %else2
// . . .
// %Result = select <16 x i1> %Mask, <16 x i32> %res.phi.select, <16 x i32> %Src
// ret <16 x i32> %Result
static void scalarizeMaskedGather(CallInst *CI) {
Value *Ptrs = CI->getArgOperand(0);
Value *Alignment = CI->getArgOperand(1);
Value *Mask = CI->getArgOperand(2);
Value *Src0 = CI->getArgOperand(3);
VectorType *VecType = cast<VectorType>(CI->getType());
Type *EltTy = VecType->getElementType();
IRBuilder<> Builder(CI->getContext());
Instruction *InsertPt = CI;
BasicBlock *IfBlock = CI->getParent();
Builder.SetInsertPoint(InsertPt);
unsigned AlignVal = cast<ConstantInt>(Alignment)->getZExtValue();
Builder.SetCurrentDebugLocation(CI->getDebugLoc());
// The result vector
Value *VResult = Src0;
unsigned VectorWidth = VecType->getNumElements();
// Shorten the way if the mask is a vector of constants.
if (isConstantIntVector(Mask)) {
for (unsigned Idx = 0; Idx < VectorWidth; ++Idx) {
if (cast<Constant>(Mask)->getAggregateElement(Idx)->isNullValue())
continue;
Value *Ptr = Builder.CreateExtractElement(Ptrs, Builder.getInt32(Idx),
"Ptr" + Twine(Idx));
LoadInst *Load =
Builder.CreateAlignedLoad(EltTy, Ptr, AlignVal, "Load" + Twine(Idx));
VResult = Builder.CreateInsertElement(
VResult, Load, Builder.getInt32(Idx), "Res" + Twine(Idx));
}
CI->replaceAllUsesWith(VResult);
CI->eraseFromParent();
return;
}
for (unsigned Idx = 0; Idx < VectorWidth; ++Idx) {
// Fill the "else" block, created in the previous iteration
//
// %Mask1 = extractelement <16 x i1> %Mask, i32 1
// br i1 %Mask1, label %cond.load, label %else
//
Value *Predicate = Builder.CreateExtractElement(Mask, Builder.getInt32(Idx),
"Mask" + Twine(Idx));
// Create "cond" block
//
// %EltAddr = getelementptr i32* %1, i32 0
// %Elt = load i32* %EltAddr
// VResult = insertelement <16 x i32> VResult, i32 %Elt, i32 Idx
//
BasicBlock *CondBlock = IfBlock->splitBasicBlock(InsertPt, "cond.load");
Builder.SetInsertPoint(InsertPt);
Value *Ptr = Builder.CreateExtractElement(Ptrs, Builder.getInt32(Idx),
"Ptr" + Twine(Idx));
LoadInst *Load =
Builder.CreateAlignedLoad(EltTy, Ptr, AlignVal, "Load" + Twine(Idx));
Value *NewVResult = Builder.CreateInsertElement(VResult, Load,
Builder.getInt32(Idx),
"Res" + Twine(Idx));
// Create "else" block, fill it in the next iteration
BasicBlock *NewIfBlock = CondBlock->splitBasicBlock(InsertPt, "else");
Builder.SetInsertPoint(InsertPt);
Instruction *OldBr = IfBlock->getTerminator();
BranchInst::Create(CondBlock, NewIfBlock, Predicate, OldBr);
OldBr->eraseFromParent();
BasicBlock *PrevIfBlock = IfBlock;
IfBlock = NewIfBlock;
PHINode *Phi = Builder.CreatePHI(VecType, 2, "res.phi.else");
Phi->addIncoming(NewVResult, CondBlock);
Phi->addIncoming(VResult, PrevIfBlock);
VResult = Phi;
}
CI->replaceAllUsesWith(VResult);
CI->eraseFromParent();
}
// Translate a masked scatter intrinsic, like
// void @llvm.masked.scatter.v16i32(<16 x i32> %Src, <16 x i32*>* %Ptrs, i32 4,
// <16 x i1> %Mask)
// to a chain of basic blocks, that stores element one-by-one if
// the appropriate mask bit is set.
//
// %Ptrs = getelementptr i32, i32* %ptr, <16 x i64> %ind
// %Mask0 = extractelement <16 x i1> %Mask, i32 0
// br i1 %Mask0, label %cond.store, label %else
//
// cond.store:
// %Elt0 = extractelement <16 x i32> %Src, i32 0
// %Ptr0 = extractelement <16 x i32*> %Ptrs, i32 0
// store i32 %Elt0, i32* %Ptr0, align 4
// br label %else
//
// else:
// %Mask1 = extractelement <16 x i1> %Mask, i32 1
// br i1 %Mask1, label %cond.store1, label %else2
//
// cond.store1:
// %Elt1 = extractelement <16 x i32> %Src, i32 1
// %Ptr1 = extractelement <16 x i32*> %Ptrs, i32 1
// store i32 %Elt1, i32* %Ptr1, align 4
// br label %else2
// . . .
static void scalarizeMaskedScatter(CallInst *CI) {
Value *Src = CI->getArgOperand(0);
Value *Ptrs = CI->getArgOperand(1);
Value *Alignment = CI->getArgOperand(2);
Value *Mask = CI->getArgOperand(3);
assert(isa<VectorType>(Src->getType()) &&
"Unexpected data type in masked scatter intrinsic");
assert(isa<VectorType>(Ptrs->getType()) &&
isa<PointerType>(Ptrs->getType()->getVectorElementType()) &&
"Vector of pointers is expected in masked scatter intrinsic");
IRBuilder<> Builder(CI->getContext());
Instruction *InsertPt = CI;
BasicBlock *IfBlock = CI->getParent();
Builder.SetInsertPoint(InsertPt);
Builder.SetCurrentDebugLocation(CI->getDebugLoc());
unsigned AlignVal = cast<ConstantInt>(Alignment)->getZExtValue();
unsigned VectorWidth = Src->getType()->getVectorNumElements();
// Shorten the way if the mask is a vector of constants.
if (isConstantIntVector(Mask)) {
for (unsigned Idx = 0; Idx < VectorWidth; ++Idx) {
if (cast<ConstantVector>(Mask)->getAggregateElement(Idx)->isNullValue())
continue;
Value *OneElt = Builder.CreateExtractElement(Src, Builder.getInt32(Idx),
"Elt" + Twine(Idx));
Value *Ptr = Builder.CreateExtractElement(Ptrs, Builder.getInt32(Idx),
"Ptr" + Twine(Idx));
Builder.CreateAlignedStore(OneElt, Ptr, AlignVal);
}
CI->eraseFromParent();
return;
}
for (unsigned Idx = 0; Idx < VectorWidth; ++Idx) {
// Fill the "else" block, created in the previous iteration
//
// %Mask1 = extractelement <16 x i1> %Mask, i32 Idx
// br i1 %Mask1, label %cond.store, label %else
//
Value *Predicate = Builder.CreateExtractElement(Mask, Builder.getInt32(Idx),
"Mask" + Twine(Idx));
// Create "cond" block
//
// %Elt1 = extractelement <16 x i32> %Src, i32 1
// %Ptr1 = extractelement <16 x i32*> %Ptrs, i32 1
// %store i32 %Elt1, i32* %Ptr1
//
BasicBlock *CondBlock = IfBlock->splitBasicBlock(InsertPt, "cond.store");
Builder.SetInsertPoint(InsertPt);
Value *OneElt = Builder.CreateExtractElement(Src, Builder.getInt32(Idx),
"Elt" + Twine(Idx));
Value *Ptr = Builder.CreateExtractElement(Ptrs, Builder.getInt32(Idx),
"Ptr" + Twine(Idx));
Builder.CreateAlignedStore(OneElt, Ptr, AlignVal);
// Create "else" block, fill it in the next iteration
BasicBlock *NewIfBlock = CondBlock->splitBasicBlock(InsertPt, "else");
Builder.SetInsertPoint(InsertPt);
Instruction *OldBr = IfBlock->getTerminator();
BranchInst::Create(CondBlock, NewIfBlock, Predicate, OldBr);
OldBr->eraseFromParent();
IfBlock = NewIfBlock;
}
CI->eraseFromParent();
}
bool ScalarizeMaskedMemIntrin::runOnFunction(Function &F) {
bool EverMadeChange = false;
TTI = &getAnalysis<TargetTransformInfoWrapperPass>().getTTI(F);
bool MadeChange = true;
while (MadeChange) {
MadeChange = false;
for (Function::iterator I = F.begin(); I != F.end();) {
BasicBlock *BB = &*I++;
bool ModifiedDTOnIteration = false;
MadeChange |= optimizeBlock(*BB, ModifiedDTOnIteration);
// Restart BB iteration if the dominator tree of the Function was changed
if (ModifiedDTOnIteration)
break;
}
EverMadeChange |= MadeChange;
}
return EverMadeChange;
}
bool ScalarizeMaskedMemIntrin::optimizeBlock(BasicBlock &BB, bool &ModifiedDT) {
bool MadeChange = false;
BasicBlock::iterator CurInstIterator = BB.begin();
while (CurInstIterator != BB.end()) {
if (CallInst *CI = dyn_cast<CallInst>(&*CurInstIterator++))
MadeChange |= optimizeCallInst(CI, ModifiedDT);
if (ModifiedDT)
return true;
}
return MadeChange;
}
bool ScalarizeMaskedMemIntrin::optimizeCallInst(CallInst *CI,
bool &ModifiedDT) {
IntrinsicInst *II = dyn_cast<IntrinsicInst>(CI);
if (II) {
switch (II->getIntrinsicID()) {
default:
break;
case Intrinsic::masked_load:
// Scalarize unsupported vector masked load
if (!TTI->isLegalMaskedLoad(CI->getType())) {
scalarizeMaskedLoad(CI);
ModifiedDT = true;
return true;
}
return false;
case Intrinsic::masked_store:
if (!TTI->isLegalMaskedStore(CI->getArgOperand(0)->getType())) {
scalarizeMaskedStore(CI);
ModifiedDT = true;
return true;
}
return false;
case Intrinsic::masked_gather:
if (!TTI->isLegalMaskedGather(CI->getType())) {
scalarizeMaskedGather(CI);
ModifiedDT = true;
return true;
}
return false;
case Intrinsic::masked_scatter:
if (!TTI->isLegalMaskedScatter(CI->getArgOperand(0)->getType())) {
scalarizeMaskedScatter(CI);
ModifiedDT = true;
return true;
}
return false;
}
}
return false;
}