[FFmpeg-devel] [PATCH]Drop local label from ppc asm timer

[Reimar Döffinger]

On Sat, Jun 29, 2013 at 06:58:44PM +0200, Carl Eugen Hoyos wrote:
> Hi!
> 
> Attached patch allows compilation of ppc asm timer on aix, the aix assembler 
> does not support local labels.
> I am not sure how to "test" the patch, but I compared disassembly on the 
> following platforms (identical with and without the patch):
> ppc32 Linux
> ppc64 Linux
> ppc32 OSX
> ppc64 OSX
> 
> Please review, Carl Eugen

> diff --git a/libavutil/ppc/timer.h b/libavutil/ppc/timer.h
> index 155fc01..9ade7f5 100644
> --- a/libavutil/ppc/timer.h
> +++ b/libavutil/ppc/timer.h
> @@ -31,12 +31,11 @@ static inline uint64_t read_time(void)
>  
>       /* from section 2.2.1 of the 32-bit PowerPC PEM */
>       __asm__ volatile(
> -         "1:\n"
>           "mftbu  %2\n"
>           "mftb   %0\n"
>           "mftbu  %1\n"
>           "cmpw   %2,%1\n"
> -         "bne    1b\n"
> +         "bne    $-0x10\n"
>       : "=r"(tbl), "=r"(tbu), "=r"(temp)
>       :
>       : "cc");

Looking at this:
http://www.ibm.com/developerworks/aix/library/au-inline_assembly/
I wonder if the lack of support for local labels isn't just a myth and
we are just using them incorrectly.
Does the AIX assembler really not accept it even if 0 is used instead of
1 and the
bne 1b
is changed to
bne- 0b
?