http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60606
D.Salikhov <d.salikhov at samsung dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|RESOLVED |UNCONFIRMED
Resolution|WONTFIX |---
--- Comment #4 from D.Salikhov <d.salikhov at samsung dot com> ---
(In reply to Richard Earnshaw from comment #3)
> > register unsigned long pc asm("pc");
>
> I think it's a mistake to permit this sort of construct.
>
> What does:
>
> a = pc;
> b = a+pc;
>
> generate for b? Is it exactly twice a (the compiler doesn't see pc
> changing, so is free to assume that it doesn't), just more than twice a (how
> much more?) or just less than twice a (different scheduling)? What happens
> if the user writes
>
> pc = 3; // ???
>
> The point is that while it might be valid to use pc in assembly
> instructions, the constructs you get in high-level languages are essentially
> meaningless.
Well, even if I use PC incorrectly (actually I don't), it shouldn't lead to
ICE. At least, there should be a sensible error message from compiler but not
internal error.
>
> As has been pointed out, in the few cases where you really need to extract
> the program counter you can write an inline assembly statement that
> explicitly references the PC.
