[MergeICmps] Don't crash when memcmp is not available
Fixes clang crashing with -fno-builtin, PR37527.
llvm-svn: 332808
diff --git a/llvm/lib/Transforms/Scalar/MergeICmps.cpp b/llvm/lib/Transforms/Scalar/MergeICmps.cpp
index 57dd229..ff0183a 100644
--- a/llvm/lib/Transforms/Scalar/MergeICmps.cpp
+++ b/llvm/lib/Transforms/Scalar/MergeICmps.cpp
@@ -768,6 +768,10 @@
// The rationale is to avoid turning small chains into memcmp calls.
if (!TTI->enableMemCmpExpansion(true)) return PreservedAnalyses::all();
+ // If we don't have memcmp avaiable we can't emit calls to it.
+ if (!TLI->has(LibFunc_memcmp))
+ return PreservedAnalyses::all();
+
bool MadeChange = false;
for (auto BBIt = ++F.begin(); BBIt != F.end(); ++BBIt) {