[PATCH] D14737: Convert some ObjC msgSends to runtime calls

[John McCall via cfe-commits]

rjmccall added a comment.

In http://reviews.llvm.org/D14737#373532, @pete wrote:

> I stepped through this one in the debugger to make sure I had it right.
>
> So the reason the bit cast ends up not being needed is because we restricted this optimization to cases where the result type "isObjCObjectPointerType()" which conveniently ends up begin i8* and is exactly the same type as the message receiver.  I guess if either the receiver type or the result type wasn't represented as i8* then the IRBuilder would have crashed.
>
> If we permitted converting say messaging (int*)retain to a call to objc_retain then the bit cast would be needed.  Would you like me to permit this change on functions returning anything other than isObjCObjectPointerType(), eg, change that to "isAnyPointerType()"?


The IR type for an AST type satisfying isObjCObjectPointerType() isn't always i8*; in particular, that's not true when the receiver has a concrete class type.

A test case here would be something like:

@interface Foo

- (id) retain;

@end

...

id test(Foo *foo) {

  return [foo retain];

}

Here the receiver type will be something like %struct.Foo* and the expected return type will be i8*.


http://reviews.llvm.org/D14737