On Mon, Mar 09, 2015 at 10:05:03PM +0100, Clément Bœsch wrote: > On Mon, Mar 09, 2015 at 10:01:20PM +0100, Reimar Döffinger wrote: > > On Sun, Mar 08, 2015 at 10:32:03PM +0100, Michael Niedermayer wrote: > > > On Sat, Mar 07, 2015 at 11:44:10PM +0800, zhaoxiu.zeng wrote: > > > > From 47c997fa0623ab94a7a93b2d2e4cc4fa64c85d5f Mon Sep 17 00:00:00 2001 > > > > From: Zeng Zhaoxiu <zhaoxiu.z...@gmail.com> > > > > Date: Sat, 7 Mar 2015 23:26:42 +0800 > > > > Subject: [PATCH 1/1] avcodec/wmalossless: use av_clip_intp2 > > > > > > this breaks build on ARM > > > > > > ffmpeg/libavutil/arm/intmath.h:69:5: warning: asm operand 2 probably > > > doesn’t match constraints > > > ffmpeg/libavutil/arm/intmath.h:69:5: warning: asm operand 2 probably > > > doesn’t match constraints > > > ffmpeg/libavutil/arm/intmath.h:69:5: error: impossible constraint in ‘asm’ > > > ffmpeg/libavutil/arm/intmath.h:69:5: error: impossible constraint in ‘asm’ > > > > ARM uses asm code based on the ssat instruction. > > That one requires the number of bits to be a constant. > > This means that for ARM this function may only be used with constant > > p argument. > > I guess whether this is ok depends on whether there are other > > cases/architectures where av_clip_intp2 is actually faster than a > > normal clip even when p is not constant. > > The C code doesn't look particularly faster to me in that case, > > but I haven't tested it. > > maybe we should make use of av_builtin_constant_p()?
Assuming we want av_clip_intp2 to work for non-constant that would be an option, but note that it will basically break the optimization on non-gcc. However if we don't I am not so sure what to do about it, or can we use av_builtin_constant_p to error out compile-time? _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
