[FFmpeg-devel] [PATCH] vp9: 16bpp tm/dc/h/v intra pred simd (mostly sse2) functions.

[Ronald S. Bultje]

Hi,

On Mon, Oct 5, 2015 at 5:54 AM, Henrik Gramner <henrik at gramner.com> wrote:

> On Mon, Oct 5, 2015 at 10:55 AM, Matt Oliver <protogonoi at gmail.com> wrote:
> > This patch has broken the 32bit msvc builds:
> >
> http://fate.ffmpeg.org/report.cgi?time=20151005065109&slot=x86_32-msvc12-windows-native
> >
> > I had a look through the code but couldnt find the cause. The error
> message
> > just points to the code line for a macro instantiation and I'm not
> familiar
> > enough with the code to be able to work out where within the macro the
> > error is actually occurring and why. So ill leave this one to someone
> more
> > familiar with the code.
>
> I see where the problem is.
>
> Using stack space in cglobal requires an extra register if the stack
> alignment is less than mmsize (32-bit msvc only has 4-byte stack
> alignment), and if the function already utilizes all available
> registers that will result in failure.
>
> The fix is either to reduce the number of registers used by the
> function or to only enable the function on x86-32 if the stack is at
> least 16-byte aligned. x86inc has the variable STACK_ALIGNMENT which
> can be tested for this, in C there's the HAVE_ALIGNED_STACK define
> which is set if the stack is 16-byte aligned.


Yeah, it should use 6 regs, I'll send a patch.

Ronald