Re: Mark bitrevX() functions as const

[David Howells <dhowells@redhat.com>]

Jeff Garzik <jeff@garzik.org> wrote:

> * overall, I agree with this type of change.  several Linux lib functions
> could use this sort of annotation.

Yes.  I just happened to notice bitrev.c at the end of my git pull and wondered
if it was what it sounded like...

> * I question its usefulness on static [inline] functions, because the compiler
> should be able to figure out side effects.  have you examined before-and-after
> asm to see if the code generation changes for the inlined area?

It doesn't actually make any difference, but I think such functions should be
so marked anyway: it gives both the code writer and the compiler more
information (though they're both free to ignore it if they like).

> * naked __attribute__ is ugly.  define something short and memorable in
> include/linux/compiler.h.

I'm not sure that's a good idea.  You have to be careful not to cause confusion
with ordinary "const".

> * another annotation to consider is C99 keyword 'restrict'.

Indeed, though I presume you don't mean in this particular case...

David