[FFmpeg-cvslog] r21432 - trunk/libavcodec/h264_cavlc.c
Michael Niedermayer
michaelni
Mon Jan 25 10:23:17 CET 2010
On Mon, Jan 25, 2010 at 10:13:47AM +0100, Michael Niedermayer wrote:
> On Sun, Jan 24, 2010 at 11:59:25PM +0000, M?ns Rullg?rd wrote:
> > michael <subversion at mplayerhq.hu> writes:
> >
> > > Author: michael
> > > Date: Sun Jan 24 19:42:22 2010
> > > New Revision: 21432
> > >
> > > Log:
> > > a[b-1] -> (a-1)[b].
> > > Helps gcc not to add seperate -1 instructions.
> >
> > Do you have some asm to illustrate?
>
> from h264_cavlc.c with this patch
> and thats with gcc-4.4 (Debian 4.4.3-1) 4.4.3
>
> before:
>
> movl %eax, %edx
> movl %eax, %ecx
> leal -1(%rbp), %r10d <-----------
> shrl $3, %edx
> andl $7, %ecx
> mov %edx, %edx
> movl (%r11,%rdx), %edx
> bswap %edx
> sall %cl, %edx
> movslq %r10d,%rcx <-----------
> leaq (%rcx,%rcx,2), %r12 <-----------
> shrl $-9, %edx
> mov %edx, %edx
> leaq 0(,%rdx,4), %rcx
> addq total_zeros_vlc+8(,%r12,8), %rcx
>
> after:
> movl %eax, %edx
> movl %eax, %ecx
> shrl $3, %edx
> andl $7, %ecx
> mov %edx, %edx
> movl (%r11,%rdx), %edx
> bswap %edx
> sall %cl, %edx
> movslq %ebp,%rcx <-------------
> leaq -3(%rcx,%rcx,2), %r10 <-------------
> shrl $-9, %edx
> mov %edx, %edx
> leaq 0(,%rdx,4), %rcx
> addq total_zeros_vlc+8(,%r10,8), %rcx
>
> you can also see 2 of the
> mov %edx, %edx
> in there that i spoke off
And if someone would be reporting these 2 issues to gcc devs that would
be great! Iam a little too busy ATMwith h264, maintaining ffmpeg and
everything else to do find a minimal testcase and submit that
[...]
--
Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
Frequently ignored awnser#1 FFmpeg bugs should be sent to our bugtracker. User
questions about the command line tools should be sent to the ffmpeg-user ML.
And questions about how to use libav* should be sent to the libav-user ML.
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