[x264-devel] Re: [Patch] x264 on ppc without altivec

[Guillaume POIRIER]

Hi,

On 3/14/07, Sam Hocevar <sam at zoy.org> wrote:
> On Mon, Mar 05, 2007, Alexis Ballier wrote:
>
> > But then, I don't understand why the code works in a simple program and
> > not in x264.
> >
> > by the way :
> > $gcc -maltivec -mabi=altivec toto.c
> > $./a.out
> > 0
> > $
>
>    It's because your toto.c does not cause gcc to generate AltiVec code,
> but it may happen (http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=408918).
>
>    I added proper runtime AltiVec detection, as well as a fix for the
> makefile so that only ppc/*.c files get compiled with the AltiVec flags,
> can you give the current trunk a try?

I tried on POWER5 with very latest SVN (r630):
 ./configure switches are: --enable-debug --disable-pthread

gdb ./tools/checkasm
GNU gdb 6.4.90-debian
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This GDB was configured as "powerpc-linux-gnu"...Using host
libthread_db library "/lib/tls/libthread_db.so.1".

(gdb) r
Starting program: /home/contest/gpoirier/x264/tools/checkasm
x264: using random seed 1712781642
x264: ALTIVEC against C

Program received signal SIGILL, Illegal instruction.
pixel_sad_16x16_altivec (
    pix1=0x10036020
"\202p?~\222??\234?\034?\216\016???J\003?\b?:@<?=.\210#?\001\"|D??R\001?\233\2253????\fF???\t_?H?1?\221\235O\207\021?Y\2272Z??p?$w\022A[?\227nX
?\033\222D\023?\206?0???Y~m<\031e\035??gn?\202*\217\a\213\233#\f/?\034}?
9??4DO??? F>?=??\\\224?\231\003\016ҧ?\204?T~????\177U?", i_pix1=32,
    pix2=0x10036450
"\210¯\016L?:??5??Ws?@\036?\201`\006\216?\bX??<??]K%ILs?\223=\212?ûǯ??\210\213\226{*\n\031X??֠\214F\\?\001?0?\221\027?M?q?\025a?m??\006\212{Q?\002\0257\033\230.\214?\216g?\236\024X??0RET\236?y#?\205??=rM\227??X??!f;?????\tb?\213^??3?????\223???r\221\036?L\214?\030X\001??\203?[?*?IAd\024\"\v,\227?d???\r?n\202?|?\036\032\026I\vb?/?\033\025)8~?"...,
i_pix2=16) at common/ppc/pixel.c:64
64      PIXEL_SAD_ALTIVEC( pixel_sad_16x16_altivec, 16, 16, s,  3 )
(gdb) bt
#0  pixel_sad_16x16_altivec (
    pix1=0x10036020
"\202p?~\222??\234?\034?\216\016???J\003?\b?:@<?=.\210#?\001\"|D??R\001?\233\2253????\fF???\t_?H?1?\221\235O\207\021?Y\2272Z??p?$w\022A[?\227nX
?\033\222D\023?\206?0???Y~m<\031e\035??gn?\202*\217\a\213\233#\f/?\034}?
9??4DO??? F>?=??\\\224?\231\003\016ҧ?\204?T~????\177U?", i_pix1=32,
    pix2=0x10036450
"\210¯\016L?:??5??Ws?@\036?\201`\006\216?\bX??<??]K%ILs?\223=\212?ûǯ??\210\213\226{*\n\031X??֠\214F\\?\001?0?\221\027?M?q?\025a?m??\006\212{Q?\002\0257\033\230.\214?\216g?\236\024X??0RET\236?y#?\205??=rM\227??X??!f;?????\tb?\213^??3?????\223???r\221\036?L\214?\030X\001??\203?[?*?IAd\024\"\v,\227?d???\r?n\202?|?\036\032\026I\vb?/?\033\025)8~?"...,
i_pix2=16) at common/ppc/pixel.c:64
#1  0x10003da4 in check_all (cpu_ref=0, cpu_new=64) at tools/checkasm.c:71
#2  0x10005e18 in main (argc=<value optimized out>, argv=<value
optimized out>) at tools/checkasm.c:773
(gdb) disassemble $pc-32,$pc+32
Dump of assembler code for function pixel_sad_16x16_altivec:
0x1001a104 <pixel_sad_16x16_altivec+0>: stwu    r1,-32(r1)
0x1001a108 <pixel_sad_16x16_altivec+4>: vspltisb v10,0
0x1001a10c <pixel_sad_16x16_altivec+8>: vor     v11,v10,v10
0x1001a110 <pixel_sad_16x16_altivec+12>:        li      r0,16
0x1001a114 <pixel_sad_16x16_altivec+16>:        mtctr   r0
0x1001a118 <pixel_sad_16x16_altivec+20>:        lvx     v13,r0,r3
0x1001a11c <pixel_sad_16x16_altivec+24>:        lvsl    v1,r0,r3
0x1001a120 <pixel_sad_16x16_altivec+28>:        addi    r9,r3,15
0x1001a124 <pixel_sad_16x16_altivec+32>:        lvx     v0,r0,r9
0x1001a128 <pixel_sad_16x16_altivec+36>:        vperm   v13,v13,v0,v1
0x1001a12c <pixel_sad_16x16_altivec+40>:        lvx     v1,r0,r5
0x1001a130 <pixel_sad_16x16_altivec+44>:        lvsl    v12,r0,r5
0x1001a134 <pixel_sad_16x16_altivec+48>:        addi    r9,r5,15
0x1001a138 <pixel_sad_16x16_altivec+52>:        lvx     v0,r0,r9
0x1001a13c <pixel_sad_16x16_altivec+56>:        vperm   v1,v1,v0,v12
0x1001a140 <pixel_sad_16x16_altivec+60>:        vmaxub  v0,v13,v1
0x1001a144 <pixel_sad_16x16_altivec+64>:        vminub  v13,v13,v1
0x1001a148 <pixel_sad_16x16_altivec+68>:        vsububm v0,v0,v13
0x1001a14c <pixel_sad_16x16_altivec+72>:        vsum4ubs v11,v0,v11
0x1001a150 <pixel_sad_16x16_altivec+76>:        add     r3,r3,r4
0x1001a154 <pixel_sad_16x16_altivec+80>:        add     r5,r5,r6
0x1001a158 <pixel_sad_16x16_altivec+84>:        bdnz+   0x1001a118
<pixel_sad_16x16_altivec+20>
0x1001a15c <pixel_sad_16x16_altivec+88>:        vsumsws v0,v11,v10
0x1001a160 <pixel_sad_16x16_altivec+92>:        vspltw  v0,v0,3
0x1001a164 <pixel_sad_16x16_altivec+96>:        addi    r9,r1,16
0x1001a168 <pixel_sad_16x16_altivec+100>:       stvewx  v0,r0,r9
0x1001a16c <pixel_sad_16x16_altivec+104>:       lwz     r3,16(r1)
0x1001a170 <pixel_sad_16x16_altivec+108>:       addi    r1,r1,32
0x1001a174 <pixel_sad_16x16_altivec+112>:       blr
End of assembler dump.
(gdb)


It still looks Altivec code is enabled.... bummer!

Guillaume