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[AMDGPU] Use reverse iteration in CodeGenPrepare #145484

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[AMDGPU] Use reverse iteration in CodeGenPrepare #145484

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82 changes: 29 additions & 53 deletions llvm/lib/Target/AMDGPU/AMDGPUCodeGenPrepare.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -15,6 +15,7 @@
#include "AMDGPU.h"
#include "AMDGPUTargetMachine.h"
#include "SIModeRegisterDefaults.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/Analysis/AssumptionCache.h"
#include "llvm/Analysis/ConstantFolding.h"
#include "llvm/Analysis/TargetLibraryInfo.h"
Expand Down Expand Up @@ -109,6 +110,7 @@ class AMDGPUCodeGenPrepareImpl
bool FlowChanged = false;
mutable Function *SqrtF32 = nullptr;
mutable Function *LdexpF32 = nullptr;
mutable SetVector<Value *> DeadVals;
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I don't think this needs to be a set, the iteration shouldn't revisit the same instruction twice (at least other IR combiner passes seem to all use vectors)

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I didn't use a set because I thought we could visit twice, I used one because I call the recursive delete function and I need to avoid cases where it may delete another instruction in that set (and then we visit a dead pointer).

I can use a vector + find of course if you prefer


DenseMap<const PHINode *, bool> BreakPhiNodesCache;

Expand Down Expand Up @@ -285,28 +287,19 @@ bool AMDGPUCodeGenPrepareImpl::run() {
BreakPhiNodesCache.clear();
bool MadeChange = false;

Function::iterator NextBB;
for (Function::iterator FI = F.begin(), FE = F.end(); FI != FE; FI = NextBB) {
BasicBlock *BB = &*FI;
NextBB = std::next(FI);

BasicBlock::iterator Next;
for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E;
I = Next) {
Next = std::next(I);

MadeChange |= visit(*I);

if (Next != E) { // Control flow changed
BasicBlock *NextInstBB = Next->getParent();
if (NextInstBB != BB) {
BB = NextInstBB;
E = BB->end();
FE = F.end();
}
}
for (BasicBlock &BB : reverse(F)) {
for (Instruction &I : make_early_inc_range(reverse(BB))) {
if (!DeadVals.contains(&I))
MadeChange |= visit(I);
}
}

while (!DeadVals.empty()) {
RecursivelyDeleteTriviallyDeadInstructions(
DeadVals.pop_back_val(), TLI, /*MSSAU*/ nullptr,
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Suggested change
DeadVals.pop_back_val(), TLI, /*MSSAU*/ nullptr,
DeadVals.pop_back_val(), TLI, /*MSSAU=*/ nullptr,

[&](Value *V) { DeadVals.remove(V); });
}

return MadeChange;
}

Expand Down Expand Up @@ -426,7 +419,7 @@ bool AMDGPUCodeGenPrepareImpl::replaceMulWithMul24(BinaryOperator &I) const {
Value *NewVal = insertValues(Builder, Ty, ResultVals);
NewVal->takeName(&I);
I.replaceAllUsesWith(NewVal);
I.eraseFromParent();
DeadVals.insert(&I);

return true;
}
Expand Down Expand Up @@ -500,10 +493,10 @@ bool AMDGPUCodeGenPrepareImpl::foldBinOpIntoSelect(BinaryOperator &BO) const {
FoldedT, FoldedF);
NewSelect->takeName(&BO);
BO.replaceAllUsesWith(NewSelect);
BO.eraseFromParent();
DeadVals.insert(&BO);
if (CastOp)
CastOp->eraseFromParent();
Sel->eraseFromParent();
DeadVals.insert(CastOp);
DeadVals.insert(Sel);
return true;
}

Expand Down Expand Up @@ -900,7 +893,7 @@ bool AMDGPUCodeGenPrepareImpl::visitFDiv(BinaryOperator &FDiv) {
if (NewVal) {
FDiv.replaceAllUsesWith(NewVal);
NewVal->takeName(&FDiv);
RecursivelyDeleteTriviallyDeadInstructions(&FDiv, TLI);
DeadVals.insert(&FDiv);
}

return true;
Expand Down Expand Up @@ -1310,7 +1303,8 @@ within the byte are all 0.
static bool tryNarrowMathIfNoOverflow(Instruction *I,
const SITargetLowering *TLI,
const TargetTransformInfo &TTI,
const DataLayout &DL) {
const DataLayout &DL,
SetVector<Value *> &DeadVals) {
unsigned Opc = I->getOpcode();
Type *OldType = I->getType();

Expand Down Expand Up @@ -1365,7 +1359,7 @@ static bool tryNarrowMathIfNoOverflow(Instruction *I,

Value *Zext = Builder.CreateZExt(Arith, OldType);
I->replaceAllUsesWith(Zext);
I->eraseFromParent();
DeadVals.insert(I);
return true;
}

Expand All @@ -1376,7 +1370,7 @@ bool AMDGPUCodeGenPrepareImpl::visitBinaryOperator(BinaryOperator &I) {
if (UseMul24Intrin && replaceMulWithMul24(I))
return true;
if (tryNarrowMathIfNoOverflow(&I, ST.getTargetLowering(),
TM.getTargetTransformInfo(F), DL))
TM.getTargetTransformInfo(F), DL, DeadVals))
return true;

bool Changed = false;
Expand Down Expand Up @@ -1441,7 +1435,7 @@ bool AMDGPUCodeGenPrepareImpl::visitBinaryOperator(BinaryOperator &I) {

if (NewDiv) {
I.replaceAllUsesWith(NewDiv);
I.eraseFromParent();
DeadVals.insert(&I);
Changed = true;
}
}
Expand Down Expand Up @@ -1497,7 +1491,7 @@ bool AMDGPUCodeGenPrepareImpl::visitLoadInst(LoadInst &I) {
Value *ValTrunc = Builder.CreateTrunc(WidenLoad, IntNTy);
Value *ValOrig = Builder.CreateBitCast(ValTrunc, I.getType());
I.replaceAllUsesWith(ValOrig);
I.eraseFromParent();
DeadVals.insert(&I);
return true;
}

Expand Down Expand Up @@ -1539,7 +1533,7 @@ bool AMDGPUCodeGenPrepareImpl::visitSelectInst(SelectInst &I) {

Fract->takeName(&I);
I.replaceAllUsesWith(Fract);
RecursivelyDeleteTriviallyDeadInstructions(&I, TLI);
DeadVals.insert(&I);
return true;
}

Expand Down Expand Up @@ -1827,7 +1821,7 @@ bool AMDGPUCodeGenPrepareImpl::visitPHINode(PHINode &I) {
}

I.replaceAllUsesWith(Vec);
I.eraseFromParent();
DeadVals.insert(&I);
return true;
}

Expand Down Expand Up @@ -1908,7 +1902,7 @@ bool AMDGPUCodeGenPrepareImpl::visitAddrSpaceCastInst(AddrSpaceCastInst &I) {
auto *Intrin = B.CreateIntrinsic(
I.getType(), Intrinsic::amdgcn_addrspacecast_nonnull, {I.getOperand(0)});
I.replaceAllUsesWith(Intrin);
I.eraseFromParent();
DeadVals.insert(&I);
return true;
}

Expand Down Expand Up @@ -2005,16 +1999,10 @@ bool AMDGPUCodeGenPrepareImpl::visitFMinLike(IntrinsicInst &I) {
Value *Fract = applyFractPat(Builder, FractArg);
Fract->takeName(&I);
I.replaceAllUsesWith(Fract);

RecursivelyDeleteTriviallyDeadInstructions(&I, TLI);
DeadVals.insert(&I);
return true;
}

static bool isOneOrNegOne(const Value *Val) {
const APFloat *C;
return match(Val, m_APFloat(C)) && C->getExactLog2Abs() == 0;
}

// Expand llvm.sqrt.f32 calls with !fpmath metadata in a semi-fast way.
bool AMDGPUCodeGenPrepareImpl::visitSqrt(IntrinsicInst &Sqrt) {
Type *Ty = Sqrt.getType()->getScalarType();
Expand All @@ -2035,18 +2023,6 @@ bool AMDGPUCodeGenPrepareImpl::visitSqrt(IntrinsicInst &Sqrt) {
if (ReqdAccuracy < 1.0f)
return false;

// FIXME: This is an ugly hack for this pass using forward iteration instead
// of reverse. If it worked like a normal combiner, the rsq would form before
// we saw a sqrt call.
auto *FDiv =
dyn_cast_or_null<FPMathOperator>(Sqrt.getUniqueUndroppableUser());
if (FDiv && FDiv->getOpcode() == Instruction::FDiv &&
FDiv->getFPAccuracy() >= 1.0f &&
canOptimizeWithRsq(FPOp, FDiv->getFastMathFlags(), SqrtFMF) &&
// TODO: We should also handle the arcp case for the fdiv with non-1 value
isOneOrNegOne(FDiv->getOperand(0)))
return false;

Value *SrcVal = Sqrt.getOperand(0);
bool CanTreatAsDAZ = canIgnoreDenormalInput(SrcVal, &Sqrt);

Expand All @@ -2070,7 +2046,7 @@ bool AMDGPUCodeGenPrepareImpl::visitSqrt(IntrinsicInst &Sqrt) {
Value *NewSqrt = insertValues(Builder, Sqrt.getType(), ResultVals);
NewSqrt->takeName(&Sqrt);
Sqrt.replaceAllUsesWith(NewSqrt);
Sqrt.eraseFromParent();
DeadVals.insert(&Sqrt);
return true;
}

Expand Down
42 changes: 21 additions & 21 deletions llvm/test/CodeGen/AMDGPU/amdgpu-codegenprepare-break-large-phis-heuristics.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -726,16 +726,16 @@ define amdgpu_kernel void @used_by_unbreakable_and_breakable_phi(<5 x double> %i
; CHECK-NEXT: [[LARGEPHI_EXTRACTSLICE815:%.*]] = extractelement <5 x double> [[LARGEPHI_INSERTSLICE4]], i64 4
; CHECK-NEXT: br label [[END]]
; CHECK: end:
; CHECK-NEXT: [[TMP5:%.*]] = phi double [ [[LARGEPHI_EXTRACTSLICE01]], [[THEN1]] ], [ [[LARGEPHI_EXTRACTSLICE1]], [[FINALLY]] ]
; CHECK-NEXT: [[TMP6:%.*]] = phi double [ [[LARGEPHI_EXTRACTSLICE22]], [[THEN1]] ], [ [[LARGEPHI_EXTRACTSLICE3]], [[FINALLY]] ]
; CHECK-NEXT: [[TMP7:%.*]] = phi double [ [[LARGEPHI_EXTRACTSLICE43]], [[THEN1]] ], [ [[LARGEPHI_EXTRACTSLICE5]], [[FINALLY]] ]
; CHECK-NEXT: [[TMP8:%.*]] = phi double [ [[LARGEPHI_EXTRACTSLICE64]], [[THEN1]] ], [ [[LARGEPHI_EXTRACTSLICE7]], [[FINALLY]] ]
; CHECK-NEXT: [[TMP9:%.*]] = phi double [ [[LARGEPHI_EXTRACTSLICE85]], [[THEN1]] ], [ [[LARGEPHI_EXTRACTSLICE9]], [[FINALLY]] ]
; CHECK-NEXT: [[TMP10:%.*]] = phi double [ [[LARGEPHI_EXTRACTSLICE011]], [[THEN1]] ], [ 0.000000e+00, [[FINALLY]] ]
; CHECK-NEXT: [[TMP11:%.*]] = phi double [ [[LARGEPHI_EXTRACTSLICE212]], [[THEN1]] ], [ 0.000000e+00, [[FINALLY]] ]
; CHECK-NEXT: [[TMP12:%.*]] = phi double [ [[LARGEPHI_EXTRACTSLICE413]], [[THEN1]] ], [ 0.000000e+00, [[FINALLY]] ]
; CHECK-NEXT: [[TMP13:%.*]] = phi double [ [[LARGEPHI_EXTRACTSLICE614]], [[THEN1]] ], [ 0.000000e+00, [[FINALLY]] ]
; CHECK-NEXT: [[TMP14:%.*]] = phi double [ [[LARGEPHI_EXTRACTSLICE815]], [[THEN1]] ], [ 0.000000e+00, [[FINALLY]] ]
; CHECK-NEXT: [[TMP5:%.*]] = phi double [ [[LARGEPHI_EXTRACTSLICE01]], [[THEN1]] ], [ 0.000000e+00, [[FINALLY]] ]
; CHECK-NEXT: [[TMP6:%.*]] = phi double [ [[LARGEPHI_EXTRACTSLICE22]], [[THEN1]] ], [ 0.000000e+00, [[FINALLY]] ]
; CHECK-NEXT: [[TMP7:%.*]] = phi double [ [[LARGEPHI_EXTRACTSLICE43]], [[THEN1]] ], [ 0.000000e+00, [[FINALLY]] ]
; CHECK-NEXT: [[TMP8:%.*]] = phi double [ [[LARGEPHI_EXTRACTSLICE64]], [[THEN1]] ], [ 0.000000e+00, [[FINALLY]] ]
; CHECK-NEXT: [[TMP9:%.*]] = phi double [ [[LARGEPHI_EXTRACTSLICE85]], [[THEN1]] ], [ 0.000000e+00, [[FINALLY]] ]
; CHECK-NEXT: [[TMP10:%.*]] = phi double [ [[LARGEPHI_EXTRACTSLICE011]], [[THEN1]] ], [ [[LARGEPHI_EXTRACTSLICE1]], [[FINALLY]] ]
; CHECK-NEXT: [[TMP11:%.*]] = phi double [ [[LARGEPHI_EXTRACTSLICE212]], [[THEN1]] ], [ [[LARGEPHI_EXTRACTSLICE3]], [[FINALLY]] ]
; CHECK-NEXT: [[TMP12:%.*]] = phi double [ [[LARGEPHI_EXTRACTSLICE413]], [[THEN1]] ], [ [[LARGEPHI_EXTRACTSLICE5]], [[FINALLY]] ]
; CHECK-NEXT: [[TMP13:%.*]] = phi double [ [[LARGEPHI_EXTRACTSLICE614]], [[THEN1]] ], [ [[LARGEPHI_EXTRACTSLICE7]], [[FINALLY]] ]
; CHECK-NEXT: [[TMP14:%.*]] = phi double [ [[LARGEPHI_EXTRACTSLICE815]], [[THEN1]] ], [ [[LARGEPHI_EXTRACTSLICE9]], [[FINALLY]] ]
; CHECK-NEXT: [[LARGEPHI_INSERTSLICE016:%.*]] = insertelement <5 x double> poison, double [[TMP10]], i64 0
; CHECK-NEXT: [[LARGEPHI_INSERTSLICE117:%.*]] = insertelement <5 x double> [[LARGEPHI_INSERTSLICE016]], double [[TMP11]], i64 1
; CHECK-NEXT: [[LARGEPHI_INSERTSLICE218:%.*]] = insertelement <5 x double> [[LARGEPHI_INSERTSLICE117]], double [[TMP12]], i64 2
Expand All @@ -746,8 +746,8 @@ define amdgpu_kernel void @used_by_unbreakable_and_breakable_phi(<5 x double> %i
; CHECK-NEXT: [[LARGEPHI_INSERTSLICE28:%.*]] = insertelement <5 x double> [[LARGEPHI_INSERTSLICE17]], double [[TMP7]], i64 2
; CHECK-NEXT: [[LARGEPHI_INSERTSLICE39:%.*]] = insertelement <5 x double> [[LARGEPHI_INSERTSLICE28]], double [[TMP8]], i64 3
; CHECK-NEXT: [[LARGEPHI_INSERTSLICE410:%.*]] = insertelement <5 x double> [[LARGEPHI_INSERTSLICE39]], double [[TMP9]], i64 4
; CHECK-NEXT: store <5 x double> [[LARGEPHI_INSERTSLICE410]], ptr [[OUT]], align 1
; CHECK-NEXT: store <5 x double> [[LARGEPHI_INSERTSLICE420]], ptr [[OUT]], align 1
; CHECK-NEXT: store <5 x double> [[LARGEPHI_INSERTSLICE410]], ptr [[OUT]], align 1
; CHECK-NEXT: ret void
;
entry:
Expand Down Expand Up @@ -1187,11 +1187,11 @@ define amdgpu_kernel void @test_breakable_chain_5_out_of_7(<5 x double> %in, ptr
; CHECK-NEXT: [[LARGEPHI_EXTRACTSLICE960:%.*]] = extractelement <5 x double> [[IN]], i64 4
; CHECK-NEXT: br i1 [[COND]], label [[END:%.*]], label [[COND5_END]]
; CHECK: cond5.end:
; CHECK-NEXT: [[TMP25:%.*]] = phi double [ [[LARGEPHI_EXTRACTSLICE041]], [[COND4_END]] ], [ [[LARGEPHI_EXTRACTSLICE1]], [[COND5_TRUE]] ]
; CHECK-NEXT: [[TMP26:%.*]] = phi double [ [[LARGEPHI_EXTRACTSLICE242]], [[COND4_END]] ], [ [[LARGEPHI_EXTRACTSLICE3]], [[COND5_TRUE]] ]
; CHECK-NEXT: [[TMP27:%.*]] = phi double [ [[LARGEPHI_EXTRACTSLICE443]], [[COND4_END]] ], [ [[LARGEPHI_EXTRACTSLICE5]], [[COND5_TRUE]] ]
; CHECK-NEXT: [[TMP28:%.*]] = phi double [ [[LARGEPHI_EXTRACTSLICE644]], [[COND4_END]] ], [ [[LARGEPHI_EXTRACTSLICE7]], [[COND5_TRUE]] ]
; CHECK-NEXT: [[TMP29:%.*]] = phi double [ [[LARGEPHI_EXTRACTSLICE845]], [[COND4_END]] ], [ [[LARGEPHI_EXTRACTSLICE9]], [[COND5_TRUE]] ]
; CHECK-NEXT: [[TMP25:%.*]] = phi double [ [[LARGEPHI_EXTRACTSLICE041]], [[COND4_END]] ], [ [[LARGEPHI_EXTRACTSLICE152]], [[COND5_TRUE]] ]
; CHECK-NEXT: [[TMP26:%.*]] = phi double [ [[LARGEPHI_EXTRACTSLICE242]], [[COND4_END]] ], [ [[LARGEPHI_EXTRACTSLICE354]], [[COND5_TRUE]] ]
; CHECK-NEXT: [[TMP27:%.*]] = phi double [ [[LARGEPHI_EXTRACTSLICE443]], [[COND4_END]] ], [ [[LARGEPHI_EXTRACTSLICE556]], [[COND5_TRUE]] ]
; CHECK-NEXT: [[TMP28:%.*]] = phi double [ [[LARGEPHI_EXTRACTSLICE644]], [[COND4_END]] ], [ [[LARGEPHI_EXTRACTSLICE758]], [[COND5_TRUE]] ]
; CHECK-NEXT: [[TMP29:%.*]] = phi double [ [[LARGEPHI_EXTRACTSLICE845]], [[COND4_END]] ], [ [[LARGEPHI_EXTRACTSLICE960]], [[COND5_TRUE]] ]
; CHECK-NEXT: [[LARGEPHI_INSERTSLICE046:%.*]] = insertelement <5 x double> poison, double [[TMP25]], i64 0
; CHECK-NEXT: [[LARGEPHI_INSERTSLICE147:%.*]] = insertelement <5 x double> [[LARGEPHI_INSERTSLICE046]], double [[TMP26]], i64 1
; CHECK-NEXT: [[LARGEPHI_INSERTSLICE248:%.*]] = insertelement <5 x double> [[LARGEPHI_INSERTSLICE147]], double [[TMP27]], i64 2
Expand All @@ -1204,11 +1204,11 @@ define amdgpu_kernel void @test_breakable_chain_5_out_of_7(<5 x double> %in, ptr
; CHECK-NEXT: [[LARGEPHI_EXTRACTSLICE859:%.*]] = extractelement <5 x double> [[LARGEPHI_INSERTSLICE450]], i64 4
; CHECK-NEXT: br label [[END]]
; CHECK: end:
; CHECK-NEXT: [[TMP30:%.*]] = phi double [ [[LARGEPHI_EXTRACTSLICE051]], [[COND5_END]] ], [ [[LARGEPHI_EXTRACTSLICE152]], [[COND5_TRUE]] ]
; CHECK-NEXT: [[TMP31:%.*]] = phi double [ [[LARGEPHI_EXTRACTSLICE253]], [[COND5_END]] ], [ [[LARGEPHI_EXTRACTSLICE354]], [[COND5_TRUE]] ]
; CHECK-NEXT: [[TMP32:%.*]] = phi double [ [[LARGEPHI_EXTRACTSLICE455]], [[COND5_END]] ], [ [[LARGEPHI_EXTRACTSLICE556]], [[COND5_TRUE]] ]
; CHECK-NEXT: [[TMP33:%.*]] = phi double [ [[LARGEPHI_EXTRACTSLICE657]], [[COND5_END]] ], [ [[LARGEPHI_EXTRACTSLICE758]], [[COND5_TRUE]] ]
; CHECK-NEXT: [[TMP34:%.*]] = phi double [ [[LARGEPHI_EXTRACTSLICE859]], [[COND5_END]] ], [ [[LARGEPHI_EXTRACTSLICE960]], [[COND5_TRUE]] ]
; CHECK-NEXT: [[TMP30:%.*]] = phi double [ [[LARGEPHI_EXTRACTSLICE051]], [[COND5_END]] ], [ [[LARGEPHI_EXTRACTSLICE1]], [[COND5_TRUE]] ]
; CHECK-NEXT: [[TMP31:%.*]] = phi double [ [[LARGEPHI_EXTRACTSLICE253]], [[COND5_END]] ], [ [[LARGEPHI_EXTRACTSLICE3]], [[COND5_TRUE]] ]
; CHECK-NEXT: [[TMP32:%.*]] = phi double [ [[LARGEPHI_EXTRACTSLICE455]], [[COND5_END]] ], [ [[LARGEPHI_EXTRACTSLICE5]], [[COND5_TRUE]] ]
; CHECK-NEXT: [[TMP33:%.*]] = phi double [ [[LARGEPHI_EXTRACTSLICE657]], [[COND5_END]] ], [ [[LARGEPHI_EXTRACTSLICE7]], [[COND5_TRUE]] ]
; CHECK-NEXT: [[TMP34:%.*]] = phi double [ [[LARGEPHI_EXTRACTSLICE859]], [[COND5_END]] ], [ [[LARGEPHI_EXTRACTSLICE9]], [[COND5_TRUE]] ]
; CHECK-NEXT: [[LARGEPHI_INSERTSLICE061:%.*]] = insertelement <5 x double> poison, double [[TMP30]], i64 0
; CHECK-NEXT: [[LARGEPHI_INSERTSLICE162:%.*]] = insertelement <5 x double> [[LARGEPHI_INSERTSLICE061]], double [[TMP31]], i64 1
; CHECK-NEXT: [[LARGEPHI_INSERTSLICE263:%.*]] = insertelement <5 x double> [[LARGEPHI_INSERTSLICE162]], double [[TMP32]], i64 2
Expand Down
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