[FFmpeg-devel] [PATCH] Remove mmx.h from dsputil_mmx.c

[Michael Niedermayer]

On Sat, Mar 14, 2009 at 12:37:54PM -0400, Alex Converse wrote:
> On Sat, Mar 14, 2009 at 1:05 AM, Michael Niedermayer <michaelni at gmx.at> wrote:
> > On Fri, Mar 13, 2009 at 08:38:09PM -0400, Alex Converse wrote:
> >> On Wed, Mar 11, 2009 at 3:44 PM, Michael Niedermayer <michaelni at gmx.at> wrote:
> >> > On Wed, Mar 11, 2009 at 03:19:03AM -0400, Alex Converse wrote:
> >> >> On Tue, Mar 10, 2009 at 10:04 PM, Michael Niedermayer <michaelni at gmx.at> wrote:
> >> >> > On Tue, Mar 10, 2009 at 09:19:56PM -0400, Alex Converse wrote:
> >> >> >> This is my first mmx patch so please bear with me.
> >> >> >
> >> >> >> diff --git a/libavcodec/x86/dsputil_mmx.c b/libavcodec/x86/dsputil_mmx.c
> >> >> >> index 2f47f5f..3771c5f 100644
> >> >> >> --- a/libavcodec/x86/dsputil_mmx.c
> >> >> >> +++ b/libavcodec/x86/dsputil_mmx.c
> >> >> >> @@ -28,7 +28,6 @@
> >> >> >> ?#include "libavcodec/mpegvideo.h"
> >> >> >> ?#include "libavcodec/simple_idct.h"
> >> >> >> ?#include "dsputil_mmx.h"
> >> >> >> -#include "mmx.h"
> >> >> >> ?#include "vp3dsp_mmx.h"
> >> >> >> ?#include "vp3dsp_sse2.h"
> >> >> >> ?#include "vp6dsp_mmx.h"
> >> >> >> @@ -278,16 +277,33 @@ static DECLARE_ALIGNED_8(const unsigned char, vector128[8]) =
> >> >> >>
> >> >> >> ?void put_signed_pixels_clamped_mmx(const DCTELEM *block, uint8_t *pixels, int line_size)
> >> >> >> ?{
> >> >> >> + ? ?const DCTELEM *p = block;
> >> >> >> + ? ?uint8_t *pix = pixels;
> >> >> >> ? ? ?int i;
> >> >> >>
> >> >> >> - ? ?movq_m2r(*vector128, mm1);
> >> >> >> - ? ?for (i = 0; i < 8; i++) {
> >> >> >> - ? ? ? ?movq_m2r(*(block), mm0);
> >> >> >> - ? ? ? ?packsswb_m2r(*(block + 4), mm0);
> >> >> >> - ? ? ? ?block += 8;
> >> >> >> - ? ? ? ?paddb_r2r(mm1, mm0);
> >> >> >> - ? ? ? ?movq_r2m(mm0, *pixels);
> >> >> >> - ? ? ? ?pixels += line_size;
> >> >> >> + ? ?__asm__ volatile ("movq %0, %%mm0" : : "m" (*vector128));
> >> >> >> + ? ?for (i = 0; i < 8; i+=4) {
> >> >> >> + ? ? ? ?__asm__ volatile (
> >> >> >> + ? ? ? ? ? ? ? ?"movq ? (%1), %%mm1 ? ? ? ? ? ? \n\t"
> >> >> >> + ? ? ? ? ? ? ? ?"movq 16(%1), %%mm2 ? ? ? ? ? ? \n\t"
> >> >> >> + ? ? ? ? ? ? ? ?"movq 32(%1), %%mm3 ? ? ? ? ? ? \n\t"
> >> >> >> + ? ? ? ? ? ? ? ?"movq 48(%1), %%mm4 ? ? ? ? ? ? \n\t"
> >> >> >> + ? ? ? ? ? ? ? ?"packsswb ?8(%1), %%mm1 ? ? ? ? \n\t"
> >> >> >> + ? ? ? ? ? ? ? ?"packsswb 24(%1), %%mm2 ? ? ? ? \n\t"
> >> >> >> + ? ? ? ? ? ? ? ?"packsswb 40(%1), %%mm3 ? ? ? ? \n\t"
> >> >> >> + ? ? ? ? ? ? ? ?"packsswb 56(%1), %%mm4 ? ? ? ? \n\t"
> >> >> >> + ? ? ? ? ? ? ? ?"paddb %%mm0, %%mm1 ? ? ? ? ? ? \n\t"
> >> >> >> + ? ? ? ? ? ? ? ?"paddb %%mm0, %%mm2 ? ? ? ? ? ? \n\t"
> >> >> >> + ? ? ? ? ? ? ? ?"paddb %%mm0, %%mm3 ? ? ? ? ? ? \n\t"
> >> >> >> + ? ? ? ? ? ? ? ?"paddb %%mm0, %%mm4 ? ? ? ? ? ? \n\t"
> >> >> >> + ? ? ? ? ? ? ? ?"movq %%mm1, (%0) ? ? ? ? ? ? ? \n\t"
> >> >> >> + ? ? ? ? ? ? ? ?"movq %%mm2, (%0, %2) ? ? ? ? ? \n\t"
> >> >> >> + ? ? ? ? ? ? ? ?"movq %%mm3, (%0, %2, 2) ? ? ? ?\n\t"
> >> >> >> + ? ? ? ? ? ? ? ?"movq %%mm4, (%0, %3) ? ? ? ? ? \n\t"
> >> >> >> + ? ? ? ? ? ? ? ?::"r" (pix), "r" (p), "r"((x86_reg)line_size), "r"((x86_reg)3*line_size)
> >> >> >> + ? ? ? ? ? ? ? ?:"memory");
> >> >> >> + ? ? ? ?p += 32;
> >> >> >> + ? ? ? ?pix += 4*line_size;
> >> >> >
> >> >> > 1. the for() should not be there, it should be in the asm()
> >> >>
> >> >> The for loop has been eliminated
> >> >>
> >> >> > 2. benchmark is always needed when messing with optimized code.
> >> >> > ? ?START/STOP_TIMER around the point that calls the changed
> >> >> > ? ?function is likely the easiest way to do it
> >> >>
> >> >> The benchmarks seem inconclusive. The unpatched version seems to start
> >> >> out faster and end slower. I don't know what of make of this.
> >> >
> >> > [...]
> >> >
> >> >> diff --git a/libavcodec/x86/dsputil_mmx.c b/libavcodec/x86/dsputil_mmx.c
> >> >> index 2f47f5f..b9679ad 100644
> >> >> --- a/libavcodec/x86/dsputil_mmx.c
> >> >> +++ b/libavcodec/x86/dsputil_mmx.c
> >> >> @@ -28,7 +28,6 @@
> >> >> ?#include "libavcodec/mpegvideo.h"
> >> >> ?#include "libavcodec/simple_idct.h"
> >> >> ?#include "dsputil_mmx.h"
> >> >> -#include "mmx.h"
> >> >> ?#include "vp3dsp_mmx.h"
> >> >> ?#include "vp3dsp_sse2.h"
> >> >> ?#include "vp6dsp_mmx.h"
> >> >> @@ -276,19 +275,39 @@ void put_pixels_clamped_mmx(const DCTELEM *block, uint8_t *pixels, int line_size
> >> >> ?static DECLARE_ALIGNED_8(const unsigned char, vector128[8]) =
> >> >> ? ?{ 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80 };
> >> >>
> >> >> +#define put_signed_pixels_clamped_mmx_half \
> >> >> + ? ? ? ? ? ?"movq ? (%1), %%mm1 ? ? ? ? ? ? ? ? \n\t"\
> >> >> + ? ? ? ? ? ?"movq 16(%1), %%mm2 ? ? ? ? ? ? ? ? \n\t"\
> >> >> + ? ? ? ? ? ?"movq 32(%1), %%mm3 ? ? ? ? ? ? ? ? \n\t"\
> >> >> + ? ? ? ? ? ?"movq 48(%1), %%mm4 ? ? ? ? ? ? ? ? \n\t"\
> >> >> + ? ? ? ? ? ?"packsswb ?8(%1), %%mm1 ? ? ? ? ? ? \n\t"\
> >> >> + ? ? ? ? ? ?"packsswb 24(%1), %%mm2 ? ? ? ? ? ? \n\t"\
> >> >> + ? ? ? ? ? ?"packsswb 40(%1), %%mm3 ? ? ? ? ? ? \n\t"\
> >> >> + ? ? ? ? ? ?"packsswb 56(%1), %%mm4 ? ? ? ? ? ? \n\t"\
> >> >> + ? ? ? ? ? ?"paddb %%mm0, %%mm1 ? ? ? ? ? ? ? ? \n\t"\
> >> >> + ? ? ? ? ? ?"paddb %%mm0, %%mm2 ? ? ? ? ? ? ? ? \n\t"\
> >> >> + ? ? ? ? ? ?"paddb %%mm0, %%mm3 ? ? ? ? ? ? ? ? \n\t"\
> >> >> + ? ? ? ? ? ?"paddb %%mm0, %%mm4 ? ? ? ? ? ? ? ? \n\t"\
> >> >> + ? ? ? ? ? ?"movq %%mm1, (%0) ? ? ? ? ? ? ? ? ? \n\t"\
> >> >> + ? ? ? ? ? ?"movq %%mm2, (%0, %2) ? ? ? ? ? ? ? \n\t"\
> >> >> + ? ? ? ? ? ?"movq %%mm3, (%0, %2, 2) ? ? ? ? ? ?\n\t"\
> >> >> + ? ? ? ? ? ?"movq %%mm4, (%0, %3) ? ? ? ? ? ? ? \n\t"
> >> >> +
> >> >> ?void put_signed_pixels_clamped_mmx(const DCTELEM *block, uint8_t *pixels, int line_size)
> >> >> ?{
> >> >> - ? ?int i;
> >> >> -
> >> >> - ? ?movq_m2r(*vector128, mm1);
> >> >> - ? ?for (i = 0; i < 8; i++) {
> >> >> - ? ? ? ?movq_m2r(*(block), mm0);
> >> >> - ? ? ? ?packsswb_m2r(*(block + 4), mm0);
> >> >> - ? ? ? ?block += 8;
> >> >> - ? ? ? ?paddb_r2r(mm1, mm0);
> >> >> - ? ? ? ?movq_r2m(mm0, *pixels);
> >> >> - ? ? ? ?pixels += line_size;
> >> >> - ? ?}
> >> >> + ? ?const DCTELEM *p = block;
> >> >> + ? ?uint8_t *pix = pixels;
> >> >> + ? ?x86_reg line_skip = line_size;
> >> >> +
> >> >> + ? ?__asm__ volatile (
> >> >> + ? ? ? ? ? ?"movq (%3), %%mm0 ? ? ? ? ? ? ? ? ? \n\t"
> >> >> + ? ? ? ? ? ?"lea (%2, %2, 2), %3 ? ? ? ? ? ? ? ?\n\t"
> >> >> + ? ? ? ? ? ?put_signed_pixels_clamped_mmx_half
> >> >> + ? ? ? ? ? ?"add $64, %1 ? ? ? ? ? ? ? ? ? ? ? ?\n\t"
> >> >> + ? ? ? ? ? ?"lea (%0, %2, 4), %0 ? ? ? ? ? ? ? ?\n\t"
> >> >> + ? ? ? ? ? ?put_signed_pixels_clamped_mmx_half
> >> >> + ? ? ? ? ? ?::"r" (pix), "r" (p), "r"(line_skip), "r" (vector128)
> >> >> + ? ? ? ? ? ?:"memory");
> >> >
> >> > you dont need the add $64, this can be done by changing the offsets
> >> > also %0,%1 and %3 are marked as input, while you change them
> >> >
> >>
> >> Fixed
> >>
> >> Do the x87 stack or the mm* registers need to be marked as clobbered?
> >
> > strictly yes but we dont do it because it works and it might be faster
> >
> >>
> >> Here is cycle estimation from Valgrind. I find it easier to read:
> >> ? ? ? ? Ir ? ? ? ? Dr ? ? ? ? Dw ? ? I1mr ? ?D1mr ? ? D1mw ?I2mr ?D2mr ? ?D2mw
> >> function put_signed_pixels_clamped_mmx:
> >> before:
> >> 16,088,784 ?6,033,294 ?2,681,464 ?122,988 ?34,505 ?259,448 ? 991 ? 292 ?27,624
> >> ? Cycle Estimation = Ir + 10*L1m + 100*L2m = 23,184,894
> >> after:
> >> 12,736,954 ?6,033,294 ?2,681,464 ? 64,595 ?33,784 ?258,686 ? 617 ? 294 ?27,622
> >> ? Cycle Estimation = Ir + 10*L1m + 100*L2m = 19,160,904
> >
> > nothing against valgrind but i prefer benchmarks done on real hardware
> > where its possible because we have more users that run ffmpeg on real
> > hw than who run it in emulators
> >
> 
> Well is there a guide to interpreting those benchmarks? I can't make
> heads or tails of them.

You can just write a tiny test program that runs a loop with START/STOP_TIMER
10000 times and have the inner loop do as many iterations as
a command line arg says
then run it with 100 and 101 and look at the benchmark scores.

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

The educated differ from the uneducated as much as the living from the
dead. -- Aristotle 
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