[FFmpeg-devel] [FFmpeg-cvslog] r12171 - trunk/doc/optimization.txt

[İsmail Dönmez]

On Thu, Feb 21, 2008 at 9:51 PM, ?smail D?nmez <ismail at namtrac.org> wrote:
> Hi,
>
>
>  On Thu, Feb 21, 2008 at 9:46 PM, Reimar D?ffinger
>  <Reimar.Doeffinger at stud.uni-karlsruhe.de> wrote:
>  > Hello,
>  >
>  > On Thu, Feb 21, 2008 at 09:16:39PM +0200, ?smail D?nmez wrote:
>  >
>  > > If you can give an example based on complex asm we can report a bug to
>  >  > gcc, just saying gcc is not a good optimizer
>  >  > does not help anyone, do we have another better open source compiler?
>  >
>  >  I doubt we have any seriously better compiler at all.
>  >
>  >
>  >  > No. So if you have a better example of bad asm produced we can ask
>  >  > gcc developers.
>  >
>  >  Not asm, but maybe someone is motivated to test this with a up-to-date
>  >  gcc on some 32 bit system:
>  >  > #include <inttypes.h>
>  >  > uint64_t a;
>  >  > uint16_t b;
>  >  > uint64_t mul(void) {
>  >  >   return a * b;
>  >  > }
>
>
>  gcc 4.4 trunk produces :
>
>         movq    _b at GOTPCREL(%rip), %rax
>         movzwl  (%rax), %eax
>         movzwl  %ax, %edx
>         movq    _a at GOTPCREL(%rip), %rax
>         movq    (%rax), %rax
>         imulq   %rdx, %rax
>         leave
>         ret

But on x86_64-apple-darwin that is, no 32bit trunk at hand.

Regards,
ismail

-- 
Never learn by your mistakes, if you do you may never dare to try again