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[LoopIdiomRecognize] Minor cleanups to the FFS idiom matching. NFC 

-Make sure of the CreateShl/LShr/AShr methods that take a uint64_t
instead of creating a ConstantInt for 1 ourselves.
-Use Builder.getInt1 or ConstantInt::getBool instead of a conditional.
-Pull out repeated calls to getType.
This commit is contained in:
Craig Topper 2021-04-07 09:44:52 -07:00
parent 3acf49829c
commit 5fc0e98d9a
1 changed files with 19 additions and 26 deletions
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45
llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp
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@ -1588,9 +1588,8 @@ bool LoopIdiomRecognize::recognizeAndInsertFFS() {
// %inc = add nsw %i.0, 1
// br i1 %tobool
const Value *Args[] = {
InitX, ZeroCheck ? ConstantInt::getTrue(InitX->getContext())
: ConstantInt::getFalse(InitX->getContext())};
const Value *Args[] = {InitX,
ConstantInt::getBool(InitX->getContext(), ZeroCheck)};
// @llvm.dbg doesn't count as they have no semantic effect.
auto InstWithoutDebugIt = CurLoop->getHeader()->instructionsWithoutDebug();
@ -1676,7 +1675,7 @@ static CallInst *createPopcntIntrinsic(IRBuilder<> &IRBuilder, Value *Val,
static CallInst *createFFSIntrinsic(IRBuilder<> &IRBuilder, Value *Val,
const DebugLoc &DL, bool ZeroCheck,
Intrinsic::ID IID) {
Value *Ops[] = {Val, ZeroCheck ? IRBuilder.getTrue() : IRBuilder.getFalse()};
Value *Ops[] = {Val, IRBuilder.getInt1(ZeroCheck)};
Type *Tys[] = {Val->getType()};
Module *M = IRBuilder.GetInsertBlock()->getParent()->getParent();
@ -1728,6 +1727,7 @@ void LoopIdiomRecognize::transformLoopToCountable(
IRBuilder<> Builder(PreheaderBr);
Builder.SetCurrentDebugLocation(DL);
// If there are no uses of CntPhi crate:
// Count = BitWidth - CTLZ(InitX);
// NewCount = Count;
// If there are uses of CntPhi create:
@ -1736,30 +1736,25 @@ void LoopIdiomRecognize::transformLoopToCountable(
Value *InitXNext;
if (IsCntPhiUsedOutsideLoop) {
if (DefX->getOpcode() == Instruction::AShr)
InitXNext =
Builder.CreateAShr(InitX, ConstantInt::get(InitX->getType(), 1));
InitXNext = Builder.CreateAShr(InitX, 1);
else if (DefX->getOpcode() == Instruction::LShr)
InitXNext =
Builder.CreateLShr(InitX, ConstantInt::get(InitX->getType(), 1));
InitXNext = Builder.CreateLShr(InitX, 1);
else if (DefX->getOpcode() == Instruction::Shl) // cttz
InitXNext =
Builder.CreateShl(InitX, ConstantInt::get(InitX->getType(), 1));
InitXNext = Builder.CreateShl(InitX, 1);
else
llvm_unreachable("Unexpected opcode!");
} else
InitXNext = InitX;
Value *FFS = createFFSIntrinsic(Builder, InitXNext, DL, ZeroCheck, IntrinID);
Value *Count = Builder.CreateSub(
ConstantInt::get(FFS->getType(), FFS->getType()->getIntegerBitWidth()),
FFS);
Value *Count =
createFFSIntrinsic(Builder, InitXNext, DL, ZeroCheck, IntrinID);
Type *CountTy = Count->getType();
Count = Builder.CreateSub(
ConstantInt::get(CountTy, CountTy->getIntegerBitWidth()), Count);
Value *NewCount = Count;
if (IsCntPhiUsedOutsideLoop) {
NewCount = Count;
Count = Builder.CreateAdd(Count, ConstantInt::get(Count->getType(), 1));
}
if (IsCntPhiUsedOutsideLoop)
Count = Builder.CreateAdd(Count, ConstantInt::get(CountTy, 1));
NewCount = Builder.CreateZExtOrTrunc(NewCount,
cast<IntegerType>(CntInst->getType()));
NewCount = Builder.CreateZExtOrTrunc(NewCount, CntInst->getType());
Value *CntInitVal = CntPhi->getIncomingValueForBlock(Preheader);
if (cast<ConstantInt>(CntInst->getOperand(1))->isOne()) {
@ -1785,14 +1780,12 @@ void LoopIdiomRecognize::transformLoopToCountable(
BasicBlock *Body = *(CurLoop->block_begin());
auto *LbBr = cast<BranchInst>(Body->getTerminator());
ICmpInst *LbCond = cast<ICmpInst>(LbBr->getCondition());
Type *Ty = Count->getType();
PHINode *TcPhi = PHINode::Create(Ty, 2, "tcphi", &Body->front());
PHINode *TcPhi = PHINode::Create(CountTy, 2, "tcphi", &Body->front());
Builder.SetInsertPoint(LbCond);
Instruction *TcDec = cast<Instruction>(
Builder.CreateSub(TcPhi, ConstantInt::get(Ty, 1),
"tcdec", false, true));
Instruction *TcDec = cast<Instruction>(Builder.CreateSub(
TcPhi, ConstantInt::get(CountTy, 1), "tcdec", false, true));
TcPhi->addIncoming(Count, Preheader);
TcPhi->addIncoming(TcDec, Body);
@ -1801,7 +1794,7 @@ void LoopIdiomRecognize::transformLoopToCountable(
(LbBr->getSuccessor(0) == Body) ? CmpInst::ICMP_NE : CmpInst::ICMP_EQ;
LbCond->setPredicate(Pred);
LbCond->setOperand(0, TcDec);
LbCond->setOperand(1, ConstantInt::get(Ty, 0));
LbCond->setOperand(1, ConstantInt::get(CountTy, 0));
// Step 3: All the references to the original counter outside
// the loop are replaced with the NewCount