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[CodeGenPrepare] Expand freeze conversion to support fcmp and icmp with null 

Summary:
This is a simple patch that expands https://reviews.llvm.org/D75859 to pointer comparison and fcmp

Checked with Alive2

Reviewers: reames, jdoerfert

Reviewed By: jdoerfert

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D76048
This commit is contained in:
Juneyoung Lee 2020-03-12 16:34:43 +09:00
parent abc238a3c7
commit c39cb1c0dd
2 changed files with 23 additions and 13 deletions
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23
llvm/lib/CodeGen/CodeGenPrepare.cpp
View File

@ -7198,16 +7198,25 @@ bool CodeGenPrepare::optimizeInst(Instruction *I, bool &ModifiedDT) {
if (FreezeInst *FI = dyn_cast<FreezeInst>(I)) { if (FreezeInst *FI = dyn_cast<FreezeInst>(I)) {
// br(freeze(icmp a, const)) -> br(icmp (freeze a), const) // br(freeze(icmp a, const)) -> br(icmp (freeze a), const)
// This helps generate efficient conditional jumps. // This helps generate efficient conditional jumps.
if (ICmpInst *II = dyn_cast<ICmpInst>(FI->getOperand(0))) { Instruction *CmpI = nullptr;
auto Op0 = II->getOperand(0), Op1 = II->getOperand(1); if (ICmpInst *II = dyn_cast<ICmpInst>(FI->getOperand(0)))
bool Const0 = isa<ConstantInt>(Op0), Const1 = isa<ConstantInt>(Op1); CmpI = II;
if (II->hasOneUse() && (Const0 || Const1)) { else if (FCmpInst *F = dyn_cast<FCmpInst>(FI->getOperand(0)))
CmpI = F->getFastMathFlags().none() ? F : nullptr;
if (CmpI && CmpI->hasOneUse()) {
auto Op0 = CmpI->getOperand(0), Op1 = CmpI->getOperand(1);
bool Const0 = isa<ConstantInt>(Op0) || isa<ConstantFP>(Op0) ||
isa<ConstantPointerNull>(Op0);
bool Const1 = isa<ConstantInt>(Op1) || isa<ConstantFP>(Op1) ||
isa<ConstantPointerNull>(Op1);
if (Const0 || Const1) {
if (!Const0 || !Const1) { if (!Const0 || !Const1) {
auto *F = new FreezeInst(Const0 ? Op1 : Op0, "", II); auto *F = new FreezeInst(Const0 ? Op1 : Op0, "", CmpI);
F->takeName(FI); F->takeName(FI);
II->setOperand(Const0 ? 1 : 0, F); CmpI->setOperand(Const0 ? 1 : 0, F);
} }
FI->replaceAllUsesWith(II); FI->replaceAllUsesWith(CmpI);
FI->eraseFromParent(); FI->eraseFromParent();
return true; return true;
} }

13
llvm/test/Transforms/CodeGenPrepare/X86/freeze-cmp.ll
View File

@ -73,9 +73,9 @@ B:
define i1 @ptrcmp(i8* %p) { define i1 @ptrcmp(i8* %p) {
; CHECK-LABEL: @ptrcmp( ; CHECK-LABEL: @ptrcmp(
; CHECK-NEXT: [[C:%.*]] = icmp eq i8* [[P:%.*]], null ; CHECK-NEXT: [[FR:%.*]] = freeze i8* [[P:%.*]]
; CHECK-NEXT: [[FR:%.*]] = freeze i1 [[C]] ; CHECK-NEXT: [[C:%.*]] = icmp eq i8* [[FR]], null
; CHECK-NEXT: ret i1 [[FR]] ; CHECK-NEXT: ret i1 [[C]]
; ;
%c = icmp eq i8* %p, null %c = icmp eq i8* %p, null
%fr = freeze i1 %c %fr = freeze i1 %c
@ -85,9 +85,9 @@ define i1 @ptrcmp(i8* %p) {
define i1 @fcmp(float %a) { define i1 @fcmp(float %a) {
; CHECK-LABEL: @fcmp( ; CHECK-LABEL: @fcmp(
; CHECK-NEXT: [[C:%.*]] = fcmp oeq float [[A:%.*]], 0.000000e+00 ; CHECK-NEXT: [[FR:%.*]] = freeze float [[A:%.*]]
; CHECK-NEXT: [[FR:%.*]] = freeze i1 [[C]] ; CHECK-NEXT: [[C:%.*]] = fcmp oeq float [[FR]], 0.000000e+00
; CHECK-NEXT: ret i1 [[FR]] ; CHECK-NEXT: ret i1 [[C]]
; ;
%c = fcmp oeq float %a, 0.0 %c = fcmp oeq float %a, 0.0
%fr = freeze i1 %c %fr = freeze i1 %c
@ -104,5 +104,6 @@ define i1 @fcmp_nan(float %a) {
%fr = freeze i1 %c %fr = freeze i1 %c
ret i1 %fr ret i1 %fr
} }
declare void @g1() declare void @g1()
declare void @g2() declare void @g2()