Commit c39cb1c0 authored by Juneyoung Lee's avatar Juneyoung Lee
Browse files

[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
parent abc238a3

llvm/lib/CodeGen/CodeGenPrepare.cpp

+16 −7
Original line number Diff line number Diff line
@@ -7198,16 +7198,25 @@ bool CodeGenPrepare::optimizeInst(Instruction *I, bool &ModifiedDT) { 
  if (FreezeInst *FI = dyn_cast<FreezeInst>(I)) {

    // br(freeze(icmp a, const)) -> br(icmp (freeze a), const)

    // This helps generate efficient conditional jumps.

    if (ICmpInst *II = dyn_cast<ICmpInst>(FI->getOperand(0))) {

      auto Op0 = II->getOperand(0), Op1 = II->getOperand(1);

      bool Const0 = isa<ConstantInt>(Op0), Const1 = isa<ConstantInt>(Op1);

      if (II->hasOneUse() && (Const0 || Const1)) {

    Instruction *CmpI = nullptr;

    if (ICmpInst *II = dyn_cast<ICmpInst>(FI->getOperand(0)))

      CmpI = II;

    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) {

          auto *F = new FreezeInst(Const0 ? Op1 : Op0, "", II);

          auto *F = new FreezeInst(Const0 ? Op1 : Op0, "", CmpI);

          F->takeName(FI);

          II->setOperand(Const0 ? 1 : 0, F);

          CmpI->setOperand(Const0 ? 1 : 0, F);

        }

        FI->replaceAllUsesWith(II);

        FI->replaceAllUsesWith(CmpI);

        FI->eraseFromParent();

        return true;

      }

llvm/test/Transforms/CodeGenPrepare/X86/freeze-cmp.ll

+7 −6
Original line number Diff line number Diff line
@@ -73,9 +73,9 @@ B: 


define i1 @ptrcmp(i8* %p) {

; CHECK-LABEL: @ptrcmp(

; CHECK-NEXT:    [[C:%.*]] = icmp eq i8* [[P:%.*]], null

; CHECK-NEXT:    [[FR:%.*]] = freeze i1 [[C]]

; CHECK-NEXT:    ret i1 [[FR]]

; CHECK-NEXT:    [[FR:%.*]] = freeze i8* [[P:%.*]]

; CHECK-NEXT:    [[C:%.*]] = icmp eq i8* [[FR]], null

; CHECK-NEXT:    ret i1 [[C]]

;

  %c = icmp eq i8* %p, null

  %fr = freeze i1 %c
@@ -85,9 +85,9 @@ define i1 @ptrcmp(i8* %p) { 


define i1 @fcmp(float %a) {

; CHECK-LABEL: @fcmp(

; CHECK-NEXT:    [[C:%.*]] = fcmp oeq float [[A:%.*]], 0.000000e+00

; CHECK-NEXT:    [[FR:%.*]] = freeze i1 [[C]]

; CHECK-NEXT:    ret i1 [[FR]]

; CHECK-NEXT:    [[FR:%.*]] = freeze float [[A:%.*]]

; CHECK-NEXT:    [[C:%.*]] = fcmp oeq float [[FR]], 0.000000e+00

; CHECK-NEXT:    ret i1 [[C]]

;

  %c = fcmp oeq float %a, 0.0

  %fr = freeze i1 %c
@@ -104,5 +104,6 @@ define i1 @fcmp_nan(float %a) { 
  %fr = freeze i1 %c

  ret i1 %fr

}



declare void @g1()

declare void @g2()