Re: [patch 06/10] Immediate Value - i386 Optimization

Jeremy Fitzhardinge
2007-07-03T23:10:43Z

Chuck Ebbert wrote:
> On 07/03/2007 04:18 PM, H. Peter Anvin wrote:
>
>> One could, though, use an indirect jump to achieve, if not as good, at
>> least most of the effect:
>>
>> movl $<patchable>,<reg>
>> jmp *<reg>
>>
>>
>
> Yeah, but there's this GCC bug:
>
> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22448
>
> You can't even dereference labels in an ASM statement.

I was told in absolute terms that any use of &&label other than to pass
it to goto was not supported, and would not be supported.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29305

Seems that passing to an asm() falls into the same class of problem I
had. I think the underlying problem is that if the code containing the
label is in an inlined function or unrolled loop, the reference can't be
resolved properly anyway.

J