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()? -- Clément B.
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