[FFmpeg-cvslog] r25254 - trunk/libavcodec/x86/h264dsp_mmx.c

[Måns Rullgård]

Michael Niedermayer <michaelni at gmx.at> writes:

> On Wed, Sep 29, 2010 at 12:19:45PM -0400, Ronald S. Bultje wrote:
>> Hi,
>> 
>> On Wed, Sep 29, 2010 at 12:03 PM, Michael Niedermayer <michaelni at gmx.at> wrote:
>> > On Wed, Sep 29, 2010 at 04:02:32PM +0200, rbultje wrote:
>> >> Author: rbultje
>> >> Date: Wed Sep 29 16:02:32 2010
>> >> New Revision: 25254
>> >>
>> >> Log:
>> >> Remove d_idx as a variable, and instead load it as a constant in the asm.
>> >> This has no measurable speed effect because the surrounding code doesn't
>> >> take advantage of this yet.
>> > [...]
>> >> @@ -125,34 +124,41 @@ static av_always_inline void h264_loop_f
>> >> ? ? ? ? ? ? ? ? ? ? ? ? ?"por ? ? ? ? ? %%mm1, %%mm0 \n"
>> >> ? ? ? ? ? ? ? ? ? ? ? ? ?"pshufw $0x4E, %%mm0, %%mm1 \n"
>> >> ? ? ? ? ? ? ? ? ? ? ? ? ?"pminub ? ? ? ?%%mm1, %%mm0 \n"
>> >> - ? ? ? ? ? ? ? ? ? ? ? ?::"r"(d_idx),
>> >> - ? ? ? ? ? ? ? ? ? ? ? ? ?"r"(ref[0]+b_idx),
>> >> - ? ? ? ? ? ? ? ? ? ? ? ? ?"r"(mv[0]+b_idx)
>> >> + ? ? ? ? ? ? ? ? ? ? ? ?::"r"(ref[0]+b_idx),
>> >> + ? ? ? ? ? ? ? ? ? ? ? ? ?"r"(mv[0]+b_idx),
>> >> + ? ? ? ? ? ? ? ? ? ? ? ? ?"i"(d_idx),
>> >> + ? ? ? ? ? ? ? ? ? ? ? ? ?"i"(d_idx+40),
>> >> + ? ? ? ? ? ? ? ? ? ? ? ? ?"i"(d_idx*4),
>> >> + ? ? ? ? ? ? ? ? ? ? ? ? ?"i"(d_idx*4+8),
>> >> + ? ? ? ? ? ? ? ? ? ? ? ? ?"i"(d_idx*4+160),
>> >> + ? ? ? ? ? ? ? ? ? ? ? ? ?"i"(d_idx*4+168)
>> >
>> > It appears that some gccs have difficulty with constant propagation, so i
>> > suspect that this has to be changed to a macro instead of a always_inline
>> > function
>> 
>> Grmbl, starting to think yasm is easier after all... Patch attached.
>
> Iam starting to think that too in this case ...

...

> either way patch ok
>
> but see it positive we learnt about %a0

Is that one of those undocumented tricks they tell you not to use?

> and that gcc 3 is not capable to propagete constants through
> always_inline functions, 

I thought that was common knowledge.

-- 
M?ns Rullg?rd
mans at mansr.com