Fix PR3298, a crash in Jump Threading. Apparently even
jump threading can have bugs, who knew? ;-)
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@61983 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/JumpThreading.cpp b/lib/Transforms/Scalar/JumpThreading.cpp
index 59af14b..94d33aa 100644
--- a/lib/Transforms/Scalar/JumpThreading.cpp
+++ b/lib/Transforms/Scalar/JumpThreading.cpp
@@ -504,6 +504,10 @@
// If the value if the load is locally available within the block, just use
// it. This frequently occurs for reg2mem'd allocas.
//cerr << "LOAD ELIMINATED:\n" << *BBIt << *LI << "\n";
+
+ // If the returned value is the load itself, replace with an undef. This can
+ // only happen in dead loops.
+ if (AvailableVal == LI) AvailableVal = UndefValue::get(LI->getType());
LI->replaceAllUsesWith(AvailableVal);
LI->eraseFromParent();
return true;