Switch invars away from using isTrapping when it really shouldn't be
using it.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@75852 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/IndVarSimplify.cpp b/lib/Transforms/Scalar/IndVarSimplify.cpp
index 1a6c6a1..0ac58f1 100644
--- a/lib/Transforms/Scalar/IndVarSimplify.cpp
+++ b/lib/Transforms/Scalar/IndVarSimplify.cpp
@@ -544,7 +544,13 @@
// New instructions were inserted at the end of the preheader.
if (isa<PHINode>(I))
break;
- if (I->isTrapping())
+ // Don't move instructions which might have side effects, since the side
+ // effects need to complete before instructions inside the loop. Also
+ // don't move instructions which might read memory, since the loop may
+ // modify memory. Note that it's okay if the instruction might have
+ // undefined behavior: LoopSimplify guarantees that the preheader
+ // dominates the exit block.
+ if (I->mayHaveSideEffects() || I->mayReadFromMemory())
continue;
// Determine if there is a use in or before the loop (direct or
// otherwise).