Commit aa6bdf9d authored by Matt Arsenault's avatar Matt Arsenault
Browse files

LoopVersioning: Respect convergent 

This changes the standalone pass only. Arguably the utility class
itself should assert there are no convergent calls. However, a target
pass with additional context may still be able to version a loop if
all of the dynamic conditions are sufficiently uniform.

llvm-svn: 363165
parent 339b39b7

llvm/lib/Transforms/Utils/LoopVersioning.cpp

+3 −2
Original line number Diff line number Diff line
@@ -280,7 +280,8 @@ public: 
    bool Changed = false;

    for (Loop *L : Worklist) {

      const LoopAccessInfo &LAI = LAA->getInfo(L);

      if (L->isLoopSimplifyForm() && (LAI.getNumRuntimePointerChecks() ||

      if (L->isLoopSimplifyForm() && !LAI.hasConvergentOp() &&

          (LAI.getNumRuntimePointerChecks() ||

           !LAI.getPSE().getUnionPredicate().isAlwaysTrue())) {

        LoopVersioning LVer(LAI, L, LI, DT, SE);

        LVer.versionLoop();

llvm/test/Transforms/LoopVersioning/convergent.ll

0 → 100644
+40 −0
Original line number Diff line number Diff line 
; RUN: opt -basicaa -loop-versioning -S < %s | FileCheck %s



target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"



; Do not version this loop because of a convergent operation



; CHECK-LABEL: @f(

; CHECK: call i32 @llvm.convergent(

; CHECK-NOT: call i32 @llvm.convergent(

define void @f(i32* %a, i32* %b, i32* %c) #0 {

entry:

  br label %for.body



for.body:                                         ; preds = %for.body, %entry

  %ind = phi i64 [ 0, %entry ], [ %add, %for.body ]



  %arrayidxA = getelementptr inbounds i32, i32* %a, i64 %ind

  %loadA = load i32, i32* %arrayidxA, align 4



  %arrayidxB = getelementptr inbounds i32, i32* %b, i64 %ind

  %loadB = load i32, i32* %arrayidxB, align 4

  %convergentB = call i32 @llvm.convergent(i32 %loadB)



  %mulC = mul i32 %loadA, %convergentB



  %arrayidxC = getelementptr inbounds i32, i32* %c, i64 %ind

  store i32 %mulC, i32* %arrayidxC, align 4



  %add = add nuw nsw i64 %ind, 1

  %exitcond = icmp eq i64 %add, 20

  br i1 %exitcond, label %for.end, label %for.body



for.end:                                          ; preds = %for.body

  ret void

}



declare i32 @llvm.convergent(i32) #1



attributes #0 = { nounwind convergent }

attributes #1 = { nounwind readnone convergent }