Okay, Thanks for clarifying. I have used many fractional multipliers, mostly not for correctness, but often for performance improvements (though I don't know why), and there are no obvious downsides, How about leaving this code?
Rémi Denis-Courmont <r...@remlab.net> 于2024年2月24日周六 15:39写道： > Hi, > > Le 24 février 2024 03:07:36 GMT+02:00, flow gg <hlefthl...@gmail.com> a > écrit : > > .ifc \len,4 > >- vsetivli zero, 5, e8, mf2, ta, ma > >+ vsetivli zero, 5, e8, m1, ta, ma > > .elseif \len == 8 > > vsetivli zero, 9, e8, m1, ta, ma > > .else > >@@ -112,9 +112,9 @@ endfunc > > vslide1down.vx v2, \dst, t5 > > > > .ifc \len,4 > >- vsetivli zero, 4, e8, mf4, ta, ma > >+ vsetivli zero, 4, e8, m1, ta, ma > > .elseif \len == 8 > >- vsetivli zero, 8, e8, mf2, ta, ma > >+ vsetivli zero, 8, e8, m1, ta, ma > > > >What are the benefits of not using fractional multipliers here? > > Insofar as E8/MF4 is guaranteed to work for Zve32x, there are no benefits > per se. > > However fractional multipliers were added to the specification to enable > addressing invididual vectors whilst the effective multiplier is larger > than one. This can only happen with mixed widths. Fractions were not > intended to make vector shorter - there is the vector length for that > already. > > That's why "E64/MF2" doesn't work, even though it's the same vector bit > size as "E8/MF2". > > > Making this > >change would result in a 10%-20% slowdown. > > That's kind of odd. This may be caused by the slides, but it's strange to > go out of the way for hardware to optimise a case that's not even intended. > > > mf2/4 m1 > >vp8_put_bilin4_h_rvv_i32: 158.7 193.7 > >vp8_put_bilin4_hv_rvv_i32: 255.7 302.7 > >vp8_put_bilin8_h_rvv_i32: 318.7 358.7 > >vp8_put_bilin8_hv_rvv_i32: 528.7 569.7 > > > >Rémi Denis-Courmont <r...@remlab.net> 于2024年2月24日周六 01:18写道： > > > >> Hi, > >> > >> + > >> +.macro bilin_h_load dst len > >> +.ifc \len,4 > >> + vsetivli zero, 5, e8, mf2, ta, ma > >> > >> Don't use fractional multipliers if you don't mix element widths. > >> > >> +.elseif \len == 8 > >> + vsetivli zero, 9, e8, m1, ta, ma > >> +.else > >> + vsetivli zero, 17, e8, m2, ta, ma > >> +.endif > >> + > >> + vle8.v \dst, (a2) > >> + vslide1down.vx v2, \dst, t5 > >> + > >> > >> +.ifc \len,4 > >> + vsetivli zero, 4, e8, mf4, ta, ma > >> > >> Same as above. > >> > >> +.elseif \len == 8 > >> + vsetivli zero, 8, e8, mf2, ta, ma > >> > >> Also. > >> > >> +.else > >> + vsetivli zero, 16, e8, m1, ta, ma > >> +.endif > >> > >> + vwmulu.vx v28, \dst, t1 > >> + vwmaccu.vx v28, a5, v2 > >> + vwaddu.wx v24, v28, t4 > >> + vnsra.wi \dst, v24, 3 > >> +.endm > >> + > >> +.macro put_vp8_bilin_h len > >> + li t1, 8 > >> + li t4, 4 > >> + li t5, 1 > >> + sub t1, t1, a5 > >> +1: > >> + addi a4, a4, -1 > >> + bilin_h_load v0, \len > >> + vse8.v v0, (a0) > >> + add a2, a2, a3 > >> + add a0, a0, a1 > >> + bnez a4, 1b > >> + > >> + ret > >> +.endm > >> + > >> +func ff_put_vp8_bilin16_h_rvv, zve32x > >> + put_vp8_bilin_h 16 > >> +endfunc > >> + > >> +func ff_put_vp8_bilin8_h_rvv, zve32x > >> + put_vp8_bilin_h 8 > >> +endfunc > >> + > >> +func ff_put_vp8_bilin4_h_rvv, zve32x > >> + put_vp8_bilin_h 4 > >> +endfunc > >> > >> -- > >> レミ・デニ-クールモン > >> http://www.remlab.net/ > >> > >> > >> > >> _______________________________________________ > >> ffmpeg-devel mailing list > >> ffmpeg-devel@ffmpeg.org > >> https://ffmpeg.org/mailman/listinfo/ffmpeg-devel > >> > >> To unsubscribe, visit link above, or email > >> ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe". > >> > >_______________________________________________ > >ffmpeg-devel mailing list > >ffmpeg-devel@ffmpeg.org > >https://ffmpeg.org/mailman/listinfo/ffmpeg-devel > > > >To unsubscribe, visit link above, or email > >ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe". > _______________________________________________ > ffmpeg-devel mailing list > ffmpeg-devel@ffmpeg.org > https://ffmpeg.org/mailman/listinfo/ffmpeg-devel > > To unsubscribe, visit link above, or email > ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe". > _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
