[analyzer] Don't try to inline if there's no region for a message receiver.

While usually we'd use a symbolic region rather than a straight-up Unknown,
we can still generate unknowns via array subscripts with symbolic indexes.
(And if this ever changes in the future, we still shouldn't crash.)

llvm-svn: 161059

clang/lib/StaticAnalyzer/Core/CallEvent.cpp

@@ -681,6 +681,9 @@ const Decl *ObjCMethodCall::getRuntimeDefinition() const {
       ReceiverT = cast<ObjCObjectPointerType>(SupersType.getTypePtr());
     } else {
       const MemRegion *Receiver = getReceiverSVal().getAsRegion();
+      if (!Receiver)
+        return 0;
+
       DynamicTypeInfo TI = getState()->getDynamicTypeInfo(Receiver);
       ReceiverT = dyn_cast<ObjCObjectPointerType>(TI.getType().getTypePtr());
     }

clang/test/Analysis/inlining/InlineObjCInstanceMethod.m

@@ -77,4 +77,10 @@
 - (int) method2 {
   return 5/_attribute; // expected-warning {{Division by zero}}
 }
-@end
+@end
+
+
+// Don't crash if we don't know the receiver's region.
+void randomlyMessageAnObject(MyClass *arr[], int i) {
+  (void)[arr[i] getInt];
+}