[FFmpeg-trac] #3048(undetermined:closed): ICL and HAVE_INLINE_ASM

[FFmpeg]

#3048: ICL and HAVE_INLINE_ASM
-------------------------------------+-------------------------------------
             Reporter:  nikolaynnov  |                    Owner:
                 Type:  defect       |                   Status:  closed
             Priority:  normal       |                Component:
              Version:  git-master   |  undetermined
             Keywords:  icl          |               Resolution:  fixed
             Blocking:               |               Blocked By:
Analyzed by developer:  0            |  Reproduced by developer:  0
-------------------------------------+-------------------------------------
Changes (by Timothy_Gu):

 * status:  new => closed
 * resolution:   => fixed


Old description:

> I have old version of ffmpeg (0.8) with was compiled with ICL compiler
> manually. Manually means what only required c-files (for 2-3 required for
> me codecs) was included in my icproj. Now I see that ffmpeg has native
> support for icl  (through --toolchain=icl). So I have compiled last
> ffmpeg (2.0.1) with standard instructions. Then I have notice that
> encoding to MPEG4/AV_CODEC_ID_MSMPEG4V2 with new ffmpeg take too much
> time. I have some tests: old ffmpeg encode test video for a 0:55 and new
> ffmpeg encode the same video for a 1:19 - it is slowly on 43%!!! It is
> unacceptable in real applications.
>
> I make some investigation and found that problem is that some
> optimizations are disabled for icl by default. The main degradation is
> that some high optimized asm code is not included in icl. HAVE_INLINE_ASM
> is 0 by default. I have defined HAVE_INLINE_ASM to 1, make code
> compilable and linkable with some minor changes and now the test video is
> encoded for 0:55 min as expected.
>
> I believe that icl build of ffmpeg have to be fully optimized by default.
> I have attached some example of how to change code to make it compilable
> with ICL and HAVE_INLINE_ASM. Please note that I have disabled some asm
> code as I don't need it for my set of codecs.
> Typically, there are 2 kind of changes:
> 1) icl doesn't know non ia32 - cltd instruction. It has to be replaced
> with cdq instruction instead.
> example:
> #ifdef __ICL
> #define MASK_ABS(mask, level)                   \
>     __asm__ ("cdq                   \n\t"      \
>              "xorl %1, %0            \n\t"      \
>              "subl %1, %0            \n\t"      \
>              : "+a"(level), "=&d"(mask))
> #else
> #define MASK_ABS(mask, level)                   \
>     __asm__ ("cltd                   \n\t"      \
>              "xorl %1, %0            \n\t"      \
>              "subl %1, %0            \n\t"      \
>              : "+a"(level), "=&d"(mask))
> #endif
> 2)
> #ifdef __ICL
>     __asm__ volatile(
>         ...
>         "movq %N, %%mm5     \n\t"
>         ...
>         : "m"(var)
>     );
> #else
>     __asm__ volatile(
>         ...
>         "movq "MANGLE(var)", %%mm5     \n\t"
>         ...
>     );
> #endif
> I believe that icl syntax will work with gcc as well. So may be the best
> solution will be to rewrite code to don't use MANGLE in movq.

New description:

 I have old version of ffmpeg (0.8) with was compiled with ICL compiler
 manually. Manually means what only required c-files (for 2-3 required for
 me codecs) was included in my icproj. Now I see that ffmpeg has native
 support for icl  (through --toolchain=icl). So I have compiled last ffmpeg
 (2.0.1) with standard instructions. Then I have notice that encoding to
 MPEG4/AV_CODEC_ID_MSMPEG4V2 with new ffmpeg take too much time. I have
 some tests: old ffmpeg encode test video for a 0:55 and new ffmpeg encode
 the same video for a 1:19 - it is slowly on 43%!!! It is unacceptable in
 real applications.

 I make some investigation and found that problem is that some
 optimizations are disabled for icl by default. The main degradation is
 that some high optimized asm code is not included in icl. HAVE_INLINE_ASM
 is 0 by default. I have defined HAVE_INLINE_ASM to 1, make code compilable
 and linkable with some minor changes and now the test video is encoded for
 0:55 min as expected.

 I believe that icl build of ffmpeg have to be fully optimized by default.
 I have attached some example of how to change code to make it compilable
 with ICL and HAVE_INLINE_ASM. Please note that I have disabled some asm
 code as I don't need it for my set of codecs.
 Typically, there are 2 kind of changes:
 1) icl doesn't know non ia32 - cltd instruction. It has to be replaced
 with cdq instruction instead.
 example:

 {{{
 #ifdef __ICL
 #define MASK_ABS(mask, level)                   \
     __asm__ ("cdq                   \n\t"      \
              "xorl %1, %0            \n\t"      \
              "subl %1, %0            \n\t"      \
              : "+a"(level), "=&d"(mask))
 #else
 #define MASK_ABS(mask, level)                   \
     __asm__ ("cltd                   \n\t"      \
              "xorl %1, %0            \n\t"      \
              "subl %1, %0            \n\t"      \
              : "+a"(level), "=&d"(mask))
 #endif
 }}}
 2)
 {{{
 #ifdef __ICL
     __asm__ volatile(
         ...
         "movq %N, %%mm5     \n\t"
         ...
         : "m"(var)
     );
 #else
     __asm__ volatile(
         ...
         "movq "MANGLE(var)", %%mm5     \n\t"
         ...
     );
 #endif
 }}}
 I believe that icl syntax will work with gcc as well. So may be the best
 solution will be to rewrite code to don't use MANGLE in movq.

--

Comment:

 Should be fixed with
 [http://git.videolan.org/?p=ffmpeg.git;a=commitdiff;h=0f2588d7e5d2bc92c0a61e8d3e32e90722d98a8e;hp=6d9bdd9d8b6aa552d7cac5d6958b70796f94ca43
 0f2588d] and
 [http://git.videolan.org/?p=ffmpeg.git;a=search;h=e4fc7e3d4de96ba16582d2500f377ecdece28401;s=Matt+Oliver;st=author
 related commits by Matt Oliver].

--
Ticket URL: <https://trac.ffmpeg.org/ticket/3048#comment:12>
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