[SimplifyLibCalls] Fix instruction misplacement in string/memory libcall optimization
When trying to optimize fortified library functions use the right
location to insert new instructions in order to preserve correct
def-use order.
This fixes an issue where a misplaced instruction definition would
happen to be *after* one of its use after a RAUW, forming invalid IR.
This behavior was introduced by r227250.
Differential Revision: http://reviews.llvm.org/D13301
rdar://problem/22802369
llvm-svn: 249092
diff --git a/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp b/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
index 763e3c0..d5d802d 100644
--- a/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
@@ -2075,13 +2075,17 @@
if (Value *SimplifiedFortifiedCI = FortifiedSimplifier.optimizeCall(CI)) {
// Try to further simplify the result.
CallInst *SimplifiedCI = dyn_cast<CallInst>(SimplifiedFortifiedCI);
- if (SimplifiedCI && SimplifiedCI->getCalledFunction())
- if (Value *V = optimizeStringMemoryLibCall(SimplifiedCI, Builder)) {
+ if (SimplifiedCI && SimplifiedCI->getCalledFunction()) {
+ // Use an IR Builder from SimplifiedCI if available instead of CI
+ // to guarantee we reach all uses we might replace later on.
+ IRBuilder<> TmpBuilder(SimplifiedCI);
+ if (Value *V = optimizeStringMemoryLibCall(SimplifiedCI, TmpBuilder)) {
// If we were able to further simplify, remove the now redundant call.
SimplifiedCI->replaceAllUsesWith(V);
SimplifiedCI->eraseFromParent();
return V;
}
+ }
return SimplifiedFortifiedCI;
}