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loop-rotate shouldn't hoist alloca instructions out of a loop. Patch by Patrik Hägglund, with slightly modified test. Issue reported by Patrik Hägglund on llvmdev.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@150642 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Eli Friedman 2012-02-16 00:41:10 +00:00
parent 8bcde2aa66
commit 5e6162e756
2 changed files with 35 additions and 1 deletions
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3
lib/Transforms/Scalar/LoopRotation.cpp
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@ -339,7 +339,8 @@ bool LoopRotate::rotateLoop(Loop *L) {
// memory (without proving that the loop doesn't write).
if (L->hasLoopInvariantOperands(Inst) &&
!Inst->mayReadFromMemory() && !Inst->mayWriteToMemory() &&
!isa<TerminatorInst>(Inst) && !isa<DbgInfoIntrinsic>(Inst)) {
!isa<TerminatorInst>(Inst) && !isa<DbgInfoIntrinsic>(Inst) &&
!isa<AllocaInst>(Inst)) {
Inst->moveBefore(LoopEntryBranch);
continue;
}

33
test/Transforms/LoopRotate/alloca.ll Normal file
View File

@ -0,0 +1,33 @@
; RUN: opt < %s -loop-rotate -S | FileCheck %s
; Test alloca in -loop-rotate.
; We expect a different value for %ptr each iteration (according to the
; definition of alloca). I.e. each @use must be paired with an alloca.
; CHECK: call void @use(i8* %
; CHECK: %ptr = alloca i8
@e = global i16 10
declare void @use(i8*)
define void @test() {
entry:
%end = load i16* @e
br label %loop
loop:
%n.phi = phi i16 [ %n, %loop.fin ], [ 0, %entry ]
%ptr = alloca i8
%cond = icmp eq i16 %n.phi, %end
br i1 %cond, label %exit, label %loop.fin
loop.fin:
%n = add i16 %n.phi, 1
call void @use(i8* %ptr)
br label %loop
exit:
ret void
}