fix PR12075, a regression in a recent transform I added. In unreachable code, gep chains can be infinite. Just like "stripPointerCasts", use a set to keep track of visited instructions so we don't recurse infinitely.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@151383 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/InstructionSimplify.cpp b/lib/Analysis/InstructionSimplify.cpp
index 9b0ce11..37253f7 100644
--- a/lib/Analysis/InstructionSimplify.cpp
+++ b/lib/Analysis/InstructionSimplify.cpp
@@ -1522,13 +1522,27 @@
/// stripPointerAdjustments - This is like Value::stripPointerCasts, but also
/// removes inbounds gep operations, regardless of their indices.
-static Value *stripPointerAdjustments(Value *V) {
- if (GEPOperator *GEP = dyn_cast<GEPOperator>(V))
- if (GEP->isInBounds())
- return stripPointerAdjustments(GEP->getOperand(0)->stripPointerCasts());
- return V;
+static Value *stripPointerAdjustmentsImpl(Value *V,
+ SmallPtrSet<GEPOperator*, 8> &VisitedGEPs) {
+ GEPOperator *GEP = dyn_cast<GEPOperator>(V);
+ if (GEP == 0 || !GEP->isInBounds())
+ return V;
+
+ // If we've already seen this GEP, we will end up infinitely looping. This
+ // can happen in unreachable code.
+ if (!VisitedGEPs.insert(GEP))
+ return V;
+
+ return stripPointerAdjustmentsImpl(GEP->getOperand(0)->stripPointerCasts(),
+ VisitedGEPs);
}
+static Value *stripPointerAdjustments(Value *V) {
+ SmallPtrSet<GEPOperator*, 8> VisitedGEPs;
+ return stripPointerAdjustmentsImpl(V, VisitedGEPs);
+}
+
+
/// SimplifyICmpInst - Given operands for an ICmpInst, see if we can
/// fold the result. If not, this returns null.
static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,