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
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