[TargetTransformInfo] Check if function pointer is valid before calling isLoweredToCall

Function isLoweredToCall can only accept non-null function pointer, but a function pointer can be null for indirect function call. So check it before calling isLoweredToCall from getInstructionLatency.

Differential Revision: https://reviews.llvm.org/D38204

llvm-svn: 314927

llvm/include/llvm/Analysis/TargetTransformInfoImpl.h

@@ -188,6 +188,8 @@ public:
   }
 
   bool isLoweredToCall(const Function *F) {
+    assert(F && "A concrete function must be provided to this routine.");
+
     // FIXME: These should almost certainly not be handled here, and instead
     // handled with the help of TLI or the target itself. This was largely
     // ported from existing analysis heuristics here so that such refactorings
@@ -828,7 +830,7 @@ public:
     // A real function call is much slower.
     if (auto *CI = dyn_cast<CallInst>(I)) {
       const Function *F = CI->getCalledFunction();
-      if (static_cast<T *>(this)->isLoweredToCall(F))
+      if (!F || static_cast<T *>(this)->isLoweredToCall(F))
         return 40;
       // Some intrinsics return a value and a flag, we use the value type
       // to decide its latency.

llvm/test/Analysis/CostModel/X86/costmodel.ll

@@ -45,6 +45,10 @@ define i64 @foo(i64 %arg) {
   ; CODESIZE: cost of 1 {{.*}} call
   %uadd = call { i32, i1 } @llvm.uadd.with.overflow.i32(i32 undef, i32 undef)
 
+  ; LATENCY:  cost of 40 {{.*}} call void undef
+  ; CODESIZE: cost of 1 {{.*}} call void undef
+  call void undef()
+
   ; LATENCY:  cost of 1 {{.*}} ret
   ; CODESIZE: cost of 1 {{.*}} ret
   ret i64 undef