[CGP] don't expand a memcmp with nobuiltin attribute

This matches the behavior used in the SDAG when expanding memcmp.

For reference, we're intentionally treating the earlier fortified call transforms differently after:
https://bugs.llvm.org/show_bug.cgi?id=23093
https://reviews.llvm.org/rL233776

One motivation for not transforming nobuiltin calls is that it can interfere with sanitizers:
https://reviews.llvm.org/D19781
https://reviews.llvm.org/D19801

Differential Revision: https://reviews.llvm.org/D34043

llvm-svn: 305007

1 files changed, 4 insertions, 6 deletions

diff --git a/llvm/lib/CodeGen/CodeGenPrepare.cpp b/llvm/lib/CodeGen/CodeGenPrepare.cpp
index b9e0e2198e1..708b45810e5 100644
--- a/llvm/lib/CodeGen/CodeGenPrepare.cpp
+++ b/llvm/lib/CodeGen/CodeGenPrepare.cpp
@@ -2406,12 +2406,10 @@ bool CodeGenPrepare::optimizeCallInst(CallInst *CI, bool& ModifiedDT) {
   }
 
   LibFunc Func;
-  if (TLInfo->getLibFunc(*CI->getCalledFunction(), Func) &&
-      Func == LibFunc_memcmp) {
-    if (expandMemCmp(CI, TTI, TLI, DL)) {
-      ModifiedDT = true;
-      return true;
-    }
+  if (TLInfo->getLibFunc(ImmutableCallSite(CI), Func) &&
+      Func == LibFunc_memcmp && expandMemCmp(CI, TTI, TLI, DL)) {
+    ModifiedDT = true;
+    return true;
   }
   return false;
 }