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Fix one bug in the latest incarnation of r209843 -- combining GEPs 

across PHI nodes. The code was computing the Idxs from the 'GEP'
variable's indices when what it wanted was Op1's indices. This caused an
ASan heap-overflow for me that pin pointed the issue when Op1 had more
indices than GEP did. =] I'll let Louis add a specific test case for
this if he wants.

llvm-svn: 209857
This commit is contained in:
Chandler Carruth 2014-05-29 23:05:52 +00:00
parent 11b49c3818
commit 3012a1b4cd
1 changed files with 13 additions and 8 deletions
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21
llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
View File

@ -1233,10 +1233,21 @@ Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
if (!Op2 || Op1->getNumOperands() != Op2->getNumOperands())
return nullptr;
// Keep track of the type as we walk the GEP.
Type *CurTy = Op1->getOperand(0)->getType()->getScalarType();
for (unsigned J = 0, F = Op1->getNumOperands(); J != F; ++J) {
if (Op1->getOperand(J)->getType() != Op2->getOperand(J)->getType())
return nullptr;
if (J > 1) {
if (CompositeType *CT = dyn_cast<CompositeType>(CurTy)) {
CurTy = CT->getTypeAtIndex(Op1->getOperand(J));
} else {
CurTy = nullptr;
}
}
if (Op1->getOperand(J) != Op2->getOperand(J)) {
if (DI == -1) {
// We have not seen any differences yet in the GEPs feeding the
@ -1245,14 +1256,8 @@ Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
// The first two arguments can vary for any GEP, the rest have to be
// static for struct slots
if (J > 1) {
SmallVector<Value*, 8> Idxs(GEP.idx_begin(), GEP.idx_begin()+J-1);
Type *Ty =
GetElementPtrInst::getIndexedType(Op1->getOperand(0)->getType(),
Idxs);
if (Ty->isStructTy())
return nullptr;
}
if (J > 1 && CurTy->isStructTy())
return nullptr;
DI = J;
} else {