fix PR13390: do not loop forever with self-referencing self instructions

llvm-svn: 160876

1 files changed, 8 insertions, 0 deletions

diff --git a/llvm/lib/Analysis/MemoryBuiltins.cpp b/llvm/lib/Analysis/MemoryBuiltins.cpp
index 4833b5212be..c0cc27b6ec5 100644
--- a/llvm/lib/Analysis/MemoryBuiltins.cpp
+++ b/llvm/lib/Analysis/MemoryBuiltins.cpp
@@ -506,6 +506,10 @@ SizeOffsetType ObjectSizeOffsetVisitor::visitPHINode(PHINode&) {
 }
 
 SizeOffsetType ObjectSizeOffsetVisitor::visitSelectInst(SelectInst &I) {
+  // ignore malformed self-looping selects
+  if (I.getTrueValue() == &I || I.getFalseValue() == &I)
+    return unknown();
+
   SizeOffsetType TrueSide  = compute(I.getTrueValue());
   SizeOffsetType FalseSide = compute(I.getFalseValue());
   if (bothKnown(TrueSide) && bothKnown(FalseSide) && TrueSide == FalseSide)
@@ -711,6 +715,10 @@ SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitPHINode(PHINode &PHI) {
 }
 
 SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitSelectInst(SelectInst &I) {
+  // ignore malformed self-looping selects
+  if (I.getTrueValue() == &I || I.getFalseValue() == &I)
+    return unknown();
+
   SizeOffsetEvalType TrueSide  = compute_(I.getTrueValue());
   SizeOffsetEvalType FalseSide = compute_(I.getFalseValue());