[Theora-dev] patch to build theora-mmx on AMD64

[Dan Lenski]

On 5/3/06, Michael Smith <msmith at xiph.org> wrote:
> >
> > I had the exact same problem.  I found this on Usenet:
> > http://groups.google.com/group/linux.debian.bugs.dist/browse_thread/thread/bbef7633760b5472/a28c7c5bfb46c85f%23a28c7c5bfb46c85f
> > It seems that the deal is that PIC and non-PIC code don't play nice on
> > x86_64, but you can get away w/it on x86_32 (I need easier
> > abbreviations!!!) so lots of libs have this problem.
>
> The problem is the global variables in a few files (e.g. V128 in
> recon_mmx.c), I'm pretty sure.
>
> Unfortunately, I don't know what the solution is. Possibly loading the
> constants into local variables (in the surrounding C code) and only
> using the locals would be a workable solution; there might be better
> ones.

Thanks for explaining that.  Fortunately there's a pretty easy fix: we
can load 64-bit immediates into general purpose registers on x86_64,
so I'm just going to clobber %rax and use it to transfer immediates
into the %mm regs.

Dan