[Ffmpeg-devel] Re: [PATCH] Fix compilation when using --disable-opts

[Reimar Döffinger]

Hello,
On Sun, Apr 01, 2007 at 11:21:05AM +0200, Michael Niedermayer wrote:
> On Sun, Apr 01, 2007 at 10:09:16AM +0200, Reimar D?ffinger wrote:
> > On Sun, Apr 01, 2007 at 02:23:48AM +0200, Alexis Ballier wrote:
> > > >It might compile but that's because it ends up disabling the asm.
> > > 
> > > which asm was disabled when building pic before
> > > http://svn.mplayerhq.hu/ffmpeg?view=rev&revision=8549
> > > 
> > > that changed from :
> > > #if defined(ARCH_X86) && !(defined(PIC) && defined(__GNUC__))
> > > to :
> > > #if defined(ARCH_X86) && defined(CONFIG_7REGS) && 
> > > defined(CONFIG_EBX_AVAILABLE)
> > 
> > It seems that for some of the code the right condition is
> > #if defined(ARCH_X86) && defined(PIC)
> > since due to the addressing modes used not allowing an extra offset due
> > to PIC, no matter how many registers are available.
> 
> which code are you talking about?
> and dont forget that data can be copied onto the stack that is nothing in
> the gcc asm docs forbids it

at least cabac.h, line 388
"movzbl "MANGLE(ff_h264_lps_range)"(%0, %%ebx, 2), %%esi\n\t"
and line 395
"movzbl "MANGLE(ff_h264_lps_range)"("ret", "range", 2), "range" \n\t"\

No way to make ff_h264_lps_range RIP-relative as needed to allow
for PIC at least on AMD64 it seems. At least that is my understanding of
the issue so far.

Greetings,
Reimar D?ffinger