Fix PR8161, in which an unreachable loop causes recursive instruction simplification to try
to replace an instruction with itself. Add a predicate to the simplifier to prevent this case.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@114097 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/InstructionSimplify.cpp b/lib/Analysis/InstructionSimplify.cpp
index b49b4d0..5bc117d 100644
--- a/lib/Analysis/InstructionSimplify.cpp
+++ b/lib/Analysis/InstructionSimplify.cpp
@@ -423,31 +423,44 @@
/// SimplifyInstruction - See if we can compute a simplified version of this
/// instruction. If not, this returns null.
Value *llvm::SimplifyInstruction(Instruction *I, const TargetData *TD) {
+ Value *Ret = 0;
switch (I->getOpcode()) {
default:
return ConstantFoldInstruction(I, TD);
case Instruction::Add:
- return SimplifyAddInst(I->getOperand(0), I->getOperand(1),
- cast<BinaryOperator>(I)->hasNoSignedWrap(),
- cast<BinaryOperator>(I)->hasNoUnsignedWrap(), TD);
+ Ret = SimplifyAddInst(I->getOperand(0), I->getOperand(1),
+ cast<BinaryOperator>(I)->hasNoSignedWrap(),
+ cast<BinaryOperator>(I)->hasNoUnsignedWrap(), TD);
+ break;
case Instruction::And:
- return SimplifyAndInst(I->getOperand(0), I->getOperand(1), TD);
+ Ret = SimplifyAndInst(I->getOperand(0), I->getOperand(1), TD);
+ break;
case Instruction::Or:
- return SimplifyOrInst(I->getOperand(0), I->getOperand(1), TD);
+ Ret = SimplifyOrInst(I->getOperand(0), I->getOperand(1), TD);
+ break;
case Instruction::ICmp:
- return SimplifyICmpInst(cast<ICmpInst>(I)->getPredicate(),
- I->getOperand(0), I->getOperand(1), TD);
+ Ret = SimplifyICmpInst(cast<ICmpInst>(I)->getPredicate(),
+ I->getOperand(0), I->getOperand(1), TD);
+ break;
case Instruction::FCmp:
- return SimplifyFCmpInst(cast<FCmpInst>(I)->getPredicate(),
- I->getOperand(0), I->getOperand(1), TD);
+ Ret = SimplifyFCmpInst(cast<FCmpInst>(I)->getPredicate(),
+ I->getOperand(0), I->getOperand(1), TD);
+ break;
case Instruction::Select:
- return SimplifySelectInst(I->getOperand(0), I->getOperand(1),
+ Ret = SimplifySelectInst(I->getOperand(0), I->getOperand(1),
I->getOperand(2), TD);
+ break;
case Instruction::GetElementPtr: {
SmallVector<Value*, 8> Ops(I->op_begin(), I->op_end());
- return SimplifyGEPInst(&Ops[0], Ops.size(), TD);
+ Ret = SimplifyGEPInst(&Ops[0], Ops.size(), TD);
+ break;
}
}
+
+ // It is possible, in situations involving unreachable loops, to
+ // have a replacement that, through recursive simplification, ends up
+ // simplifying to itself.
+ return Ret != I ? Ret : 0;
}
/// ReplaceAndSimplifyAllUses - Perform From->replaceAllUsesWith(To) and then