[SimplifyLibCalls] Don't try to simplify indirect calls.

It turns out, all callsites of the simplifier are guarded by a check for
CallInst::getCalledFunction (i.e., to make sure the callee is direct).

This check wasn't done when trying to further optimize a simplified fortified
libcall, introduced by a refactoring in r225640.

Fix that, add a testcase, and document the requirement.

llvm-svn: 225895

1 files changed, 2 insertions, 1 deletions

diff --git a/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp b/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
index fac8bb21e7f..5b4647ddcb5 100644
--- a/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
@@ -1966,7 +1966,8 @@ Value *LibCallSimplifier::optimizeCall(CallInst *CI) {
   // Also try to simplify calls to fortified library functions.
   if (Value *SimplifiedFortifiedCI = FortifiedSimplifier.optimizeCall(CI)) {
     // Try to further simplify the result.
-    if (CallInst *SimplifiedCI = dyn_cast<CallInst>(SimplifiedFortifiedCI))
+    CallInst *SimplifiedCI = dyn_cast<CallInst>(SimplifiedFortifiedCI);
+    if (SimplifiedCI && SimplifiedCI->getCalledFunction())
       if (Value *V = optimizeStringMemoryLibCall(SimplifiedCI, Builder))
         return V;
     return SimplifiedFortifiedCI;