Hi, On Sat, Jul 16, 2016 at 5:55 AM, Henrik Gramner <hen...@gramner.com> wrote:
> On Wed, Jul 13, 2016 at 6:37 PM, Ronald S. Bultje <rsbul...@gmail.com> > wrote: > > +cglobal vp9_idct_idct_32x32_add, 4, 9, 16, 2048, dst, stride, block, eob > [...] > > + movd xm0, [blockq] > > + mova m1, [pw_11585x2] > > + pmulhrsw m0, m1 > > + pmulhrsw m0, m1 > > + vpbroadcastw m0, xm0 > > + pmulhrsw m0, [pw_512] > > [..] Is it mathematically possible to merge consecutive pmulhrsw > instructions into a single one using a different constant? I'm > guessing no, but I'm not sure. To my knowledge: no. The intermediate rounding step gets rid of the least significant bits before the second mul, and merging the muls would remove this which would change the integer result. Ronald _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
