On Wed, 25 Jul 2007, Linus Torvalds wrote:
>
> Hmm. I really think you should take this up with the gcc people. That
> looks like a gcc bug - because there really is nothing that guarantees
> that the asm doesn't change the array that "x" points to, and the asm
> clearly talks about clobbering memory.
Actually, I take that back. I think gcc does the right thing, and yes,
it's explained by the memory clobber being just a blind "write to memory"
rather than read memory. My bad.
It does leave us with very few ways of saying that an asm can *read*
memory, and so it might be good to have it clarified that "volatile"
implies that (at least with the memory clobber).
Your examples are good, I think.
Linus
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