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

[İsmail Dönmez]

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

Regards,
ismail

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