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Preserve TBAA tags when doing load PRE.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121921 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dan Gohman 2010-12-15 23:53:55 +00:00
parent 3e333637f1
commit f4177aa019
2 changed files with 36 additions and 3 deletions
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11
lib/Transforms/Scalar/GVN.cpp
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@ -22,6 +22,7 @@
#include "llvm/GlobalVariable.h"
#include "llvm/Function.h"
#include "llvm/IntrinsicInst.h"
#include "llvm/LLVMContext.h"
#include "llvm/Operator.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Analysis/ConstantFolding.h"
@ -1659,9 +1660,13 @@ bool GVN::processNonLocalLoad(LoadInst *LI,
BasicBlock *UnavailablePred = I->first;
Value *LoadPtr = I->second;
Value *NewLoad = new LoadInst(LoadPtr, LI->getName()+".pre", false,
LI->getAlignment(),
UnavailablePred->getTerminator());
Instruction *NewLoad = new LoadInst(LoadPtr, LI->getName()+".pre", false,
LI->getAlignment(),
UnavailablePred->getTerminator());
// Transfer the old load's TBAA tag to the new load.
if (MDNode *Tag = LI->getMetadata(LLVMContext::MD_tbaa))
NewLoad->setMetadata(LLVMContext::MD_tbaa, Tag);
// Add the newly created load.
ValuesPerBlock.push_back(AvailableValueInBlock::get(UnavailablePred,

28
test/Transforms/GVN/preserve-tbaa.ll Normal file
View File

@ -0,0 +1,28 @@
; RUN: opt -tbaa -basicaa -gvn -S < %s | FileCheck %s
target datalayout = "e-p:64:64:64"
; GVN should preserve the TBAA tag on loads when doing PRE.
; CHECK: @test
; CHECK: %tmp33.pre = load i16* undef, align 2, !tbaa !0
; CHECK: br label %for.body
define void @test() nounwind {
entry:
br i1 undef, label %bb.nph, label %for.end
bb.nph: ; preds = %entry
br label %for.body
for.body: ; preds = %for.body, %bb.nph
%tmp33 = load i16* undef, align 2, !tbaa !0
store i16 undef, i16* undef, align 2, !tbaa !0
br i1 false, label %for.end, label %for.body
for.end: ; preds = %for.body, %entry
ret void
}
!0 = metadata !{metadata !"short", metadata !1}
!1 = metadata !{metadata !"omnipotent char", metadata !2}
!2 = metadata !{metadata !"Simple C/C++ TBAA", null}