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[InstCombine] Preserve metadata when merging loads that are phi

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arguments.

Make sure InstCombiner::FoldPHIArgLoadIntoPHI doesn't drop the following
metadata:

MD_tbaa
MD_alias_scope
MD_noalias
MD_invariant_load
MD_nonnull
MD_range

rdar://problem/17617709

Differential Revision: http://reviews.llvm.org/D12710

llvm-svn: 248419
This commit is contained in:
Akira Hatanaka 2015-09-23 18:40:57 +00:00
parent 928c33c531
commit e7bdc0a349
2 changed files with 88 additions and 6 deletions
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25
lib/Transforms/InstCombine/InstCombinePHI.cpp
View File

@ -15,6 +15,7 @@
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/Transforms/Utils/Local.h"
using namespace llvm;
#define DEBUG_TYPE "instcombine"
@ -349,24 +350,37 @@ Instruction *InstCombiner::FoldPHIArgLoadIntoPHI(PHINode &PN) {
Value *InVal = FirstLI->getOperand(0);
NewPN->addIncoming(InVal, PN.getIncomingBlock(0));
LoadInst *NewLI = new LoadInst(NewPN, "", isVolatile, LoadAlignment);
// Add all operands to the new PHI.
unsigned KnownIDs[] = {
LLVMContext::MD_tbaa,
LLVMContext::MD_range,
LLVMContext::MD_invariant_load,
LLVMContext::MD_alias_scope,
LLVMContext::MD_noalias,
LLVMContext::MD_nonnull
};
for (unsigned ID : KnownIDs)
NewLI->setMetadata(ID, FirstLI->getMetadata(ID));
// Add all operands to the new PHI and combine TBAA metadata.
for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
Value *NewInVal = cast<LoadInst>(PN.getIncomingValue(i))->getOperand(0);
LoadInst *LI = cast<LoadInst>(PN.getIncomingValue(i));
combineMetadata(NewLI, LI, KnownIDs);
Value *NewInVal = LI->getOperand(0);
if (NewInVal != InVal)
InVal = nullptr;
NewPN->addIncoming(NewInVal, PN.getIncomingBlock(i));
}
Value *PhiVal;
if (InVal) {
// The new PHI unions all of the same values together. This is really
// common, so we handle it intelligently here for compile-time speed.
PhiVal = InVal;
NewLI->setOperand(0, InVal);
delete NewPN;
} else {
InsertNewInstBefore(NewPN, PN);
PhiVal = NewPN;
}
// If this was a volatile load that we are merging, make sure to loop through
@ -376,7 +390,6 @@ Instruction *InstCombiner::FoldPHIArgLoadIntoPHI(PHINode &PN) {
for (Value *IncValue : PN.incoming_values())
cast<LoadInst>(IncValue)->setVolatile(false);
LoadInst *NewLI = new LoadInst(PhiVal, "", isVolatile, LoadAlignment);
NewLI->setDebugLoc(FirstLI->getDebugLoc());
return NewLI;
}

69
test/Transforms/InstCombine/fold-phi-load-metadata.ll Normal file
View File

@ -0,0 +1,69 @@
; RUN: opt -instcombine -S < %s | FileCheck %s
@g1 = common global i32* null, align 8
%struct.S1 = type { i32, float }
%struct.S2 = type { float, i32 }
; Check that instcombine preserves metadata when it merges two loads.
;
; CHECK: return:
; CHECK: load i32*, i32** %{{[a-z0-9.]+}}, align 8, !nonnull ![[EMPTYNODE:[0-9]+]]
; CHECK: load i32, i32* %{{[a-z0-9.]+}}, align 4, !tbaa ![[TBAA:[0-9]+]], !range ![[RANGE:[0-9]+]], !invariant.load ![[EMPTYNODE:[0-9]+]], !alias.scope ![[ALIAS_SCOPE:[0-9]+]], !noalias ![[NOALIAS:[0-9]+]]
; Function Attrs: nounwind ssp uwtable
define i32 @phi_load_metadata(%struct.S1* %s1, %struct.S2* %s2, i32 %c, i32** %x0, i32 **%x1) #0 {
entry:
%tobool = icmp eq i32 %c, 0
br i1 %tobool, label %if.end, label %if.then
if.then: ; preds = %entry
%i = getelementptr inbounds %struct.S2, %struct.S2* %s2, i64 0, i32 1
%val = load i32, i32* %i, align 4, !tbaa !0, !alias.scope !13, !noalias !14, !invariant.load !17, !range !18
%p0 = load i32*, i32** %x0, align 8, !nonnull !17
br label %return
if.end: ; preds = %entry
%i2 = getelementptr inbounds %struct.S1, %struct.S1* %s1, i64 0, i32 0
%val2 = load i32, i32* %i2, align 4, !tbaa !2, !alias.scope !15, !noalias !16, !invariant.load !17, !range !19
%p1 = load i32*, i32** %x1, align 8, !nonnull !17
br label %return
return: ; preds = %if.end, %if.then
%retval = phi i32 [ %val, %if.then ], [ %val2, %if.end ]
%pval = phi i32* [ %p0, %if.then ], [ %p1, %if.end ]
store i32* %pval, i32** @g1, align 8
ret i32 %retval
}
; CHECK: ![[EMPTYNODE]] = !{}
; CHECK: ![[TBAA]] = !{![[TAG1:[0-9]+]], ![[TAG1]], i64 0}
; CHECK: ![[TAG1]] = !{!"int", !{{[0-9]+}}, i64 0}
; CHECK: ![[RANGE]] = !{i32 10, i32 25}
; CHECK: ![[ALIAS_SCOPE]] = !{![[SCOPE0:[0-9]+]], ![[SCOPE1:[0-9]+]], ![[SCOPE2:[0-9]+]]}
; CHECK: ![[SCOPE0]] = distinct !{![[SCOPE0]], !{{[0-9]+}}, !"scope0"}
; CHECK: ![[SCOPE1]] = distinct !{![[SCOPE1]], !{{[0-9]+}}, !"scope1"}
; CHECK: ![[SCOPE2]] = distinct !{![[SCOPE2]], !{{[0-9]+}}, !"scope2"}
; CHECK: ![[NOALIAS]] = !{![[SCOPE3:[0-9]+]]}
; CHECK: ![[SCOPE3]] = distinct !{![[SCOPE3]], !{{[0-9]+}}, !"scope3"}
!0 = !{!1, !4, i64 4}
!1 = !{!"", !7, i64 0, !4, i64 4}
!2 = !{!3, !4, i64 0}
!3 = !{!"", !4, i64 0, !7, i64 4}
!4 = !{!"int", !5, i64 0}
!5 = !{!"omnipotent char", !6, i64 0}
!6 = !{!"Simple C/C++ TBAA"}
!7 = !{!"float", !5, i64 0}
!8 = !{!8, !"some domain"}
!9 = !{!9, !8, !"scope0"}
!10 = !{!10, !8, !"scope1"}
!11 = !{!11, !8, !"scope2"}
!12 = !{!12, !8, !"scope3"}
!13 = !{!9, !10}
!14 = !{!11, !12}
!15 = !{!9, !11}
!16 = !{!10, !12}
!17 = !{}
!18 = !{i32 10, i32 20}
!19 = !{i32 15, i32 25}