[Ffmpeg-devel] [PATCH] protect cmov asm sections with HAVE_CMOV
Fri Oct 20 10:03:51 CEST 2006
On Fri, Oct 20, 2006 at 09:49:24AM +0200, Guillaume POIRIER wrote:
> Now that configure script is able to "detect" if CMOV is supported, I
> guess it's time to use it where appropriate, which is just what this
> patch is supposed to do.
> Note that with this patch, CMOV_IS_FAST == HAVE_CMOV, but since we
> (can) know (after having done some benchmark) on which CPU CMOV is
> actually fast (pretty much all of them except netburst processors), we
> can make configure set CMOV_IS_FAST if HAVE_CMOV==1 && !CMPU=P4 or
> smth like that.
Patch looks fine except for
> --- libavcodec/cabac.h (revision 6742)
> +++ libavcodec/cabac.h (working copy)
> @@ -32,7 +32,9 @@
> #define CABAC_BITS 16
> #define CABAC_MASK ((1<<CABAC_BITS)-1)
> #define BRANCHLESS_CABAC_DECODER 1
> +#ifdef HAVE_CMOV
> #define CMOV_IS_FAST 1
> //#define ARCH_X86_DISABLED 1
> @@ -454,7 +456,7 @@
> -#if (defined CMOV_IS_FAST && __CPU__ >= 686)
> +#if defined CMOV_IS_FAST
This is rather silly IMO, I'd say just replace it by HAVE_CMOV.
Are there benchmarks proving that this really is slower on some
processors? Then configue should deal with this as well.
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