Re: Definition of BUG on x86

Ingo Molnar
2009-02-19T12:10:47Z

* Petr Tesarik <ptesarik@suse.cz> wrote:

> So, the only method I could invent was using gas macros. It
> works but is quite ugly, because it relies on the actual
> assembler instruction which is generated by the compiler. Now,
> AFAIK gcc has always translated "for(;;)" into a jump to self,
> and that with any conceivable compiler options, but I don't
> know anything about Intel cc.

> +static inline __noreturn void discarded_jmp(void)
> +{
> + asm volatile(".macro jmp target\n"
> + "\t.purgem jmp\n"
> + ".endm\n");
> + for (;;) ;
> +}

hm, that's very fragile.

Why not just:

static inline __noreturn void x86_u2d(void)
{
asm volatile("u2d\n");
}

If GCC emits a bogus warning about _that_, then it's a bug in
the compiler that should be fixed.

Ingo