Re: labels in inline asm

[David Daney <ddaney at avtrex dot com>]

Clifford Wolf wrote:
> Hi,
>
> sorry for asking a probably dump question. I'm trying to port SDL_gfx
> 2.0.16 to ROCK Linux atm and running into a problem wich boils down to the
> following test case:
>
> --snip--
> inline void foobar()
> {
>         asm volatile(
>                 "jz .foobar_label\n"
>                 ".foobar_label:\n"
>                 "nop"
>         );
> }

Probably you want something like:


       asm volatile(
              "jz 1f\n"
              "1:\n"
              "nop"
       );


Look at the gas documentation for 'Local Labels'.

David Daney




> int main()
> {
>         foobar();
>         foobar();
>         return 0;
> }
> --snap--
>
> when compiled with optimization (inlining enabled) this sure results in an
> assembler file with the .foobar_label defined three times:
>
> 	# gcc -O2 -c demo.c
> 	/tmp/ccx1Ibd9.s: Assembler messages:
> 	/tmp/ccx1Ibd9.s:29: Error: symbol `.foobar_label' is already defined
> 	/tmp/ccx1Ibd9.s:32: Error: symbol `.foobar_label' is already defined
>
> maybe I'm just blind but I cant find anything in the gcc info page which
> provides me with a mechanism for dynamically creating label prefixes or
> something like that which would help me generating different labels in each
> instances of the assembler template...
>
> please help.
>
> yours,
>  - clifford