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fix instcombine merging GEPs through a PHI to only make the

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result inbounds if all of the inputs are inbounds.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@125785 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2011-02-17 22:21:26 +00:00
parent 093399cbf3
commit 4bd8217af3
2 changed files with 10 additions and 5 deletions
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10
lib/Transforms/InstCombine/InstCombinePHI.cpp
View File

@ -118,6 +118,8 @@ Instruction *InstCombiner::FoldPHIArgGEPIntoPHI(PHINode &PN) {
// especially bad when the PHIs are in the header of a loop.
bool NeededPhi = false;
bool AllInBounds = true;
// Scan to see if all operands are the same opcode, and all have one use.
for (unsigned i = 1; i != PN.getNumIncomingValues(); ++i) {
GetElementPtrInst *GEP= dyn_cast<GetElementPtrInst>(PN.getIncomingValue(i));
@ -125,6 +127,8 @@ Instruction *InstCombiner::FoldPHIArgGEPIntoPHI(PHINode &PN) {
GEP->getNumOperands() != FirstInst->getNumOperands())
return 0;
AllInBounds &= GEP->isInBounds();
// Keep track of whether or not all GEPs are of alloca pointers.
if (AllBasePointersAreAllocas &&
(!isa<AllocaInst>(GEP->getOperand(0)) ||
@ -202,11 +206,11 @@ Instruction *InstCombiner::FoldPHIArgGEPIntoPHI(PHINode &PN) {
}
Value *Base = FixedOperands[0];
return cast<GEPOperator>(FirstInst)->isInBounds() ?
GetElementPtrInst::CreateInBounds(Base, FixedOperands.begin()+1,
FixedOperands.end()) :
GetElementPtrInst *NewGEP =
GetElementPtrInst::Create(Base, FixedOperands.begin()+1,
FixedOperands.end());
if (AllInBounds) NewGEP->setIsInbounds();
return NewGEP;
}

5
test/Transforms/InstCombine/phi.ll
View File

@ -125,7 +125,7 @@ Exit: ; preds = %Loop
define i32* @test8({ i32, i32 } *%A, i1 %b) {
BB0:
%X = getelementptr { i32, i32 } *%A, i32 0, i32 1
%X = getelementptr inbounds { i32, i32 } *%A, i32 0, i32 1
br i1 %b, label %BB1, label %BB2
BB1:
@ -139,7 +139,7 @@ BB2:
; CHECK: @test8
; CHECK-NOT: phi
; CHECK: BB2:
; CHECK-NEXT: %B = getelementptr
; CHECK-NEXT: %B = getelementptr %0
; CHECK-NEXT: ret i32* %B
}
@ -525,3 +525,4 @@ Exit: ; preds = %Loop
; CHECK: Exit:
; CHECK-NEXT: ret i32 %B
}