Hi! On Sun, Sep 29, 2019 at 01:38:31PM +0800, Kewen.Lin wrote: > Recently we are revisiting vectorization cost setting in > rs6000_builtin_vectorization_cost, and found the current cost of > vec_perm on VSX looks overpriced for Power8 and Power9.
Yeah it does. > The high > cost was set for Power7 single VSU pipe, but Power8 and Power9 > have supported more VSX units, Power7 has two VSU pipes, but only one permute (and only one of the other VMX units, and only one store). It can do two VSX or two classic FP, and various combinations. > the performance evaluation on > SPEC2017 Power9 shows 2%+ gain on 538.imagick_r, while SPEC2006/ > SPEC2017 Power8 evaluations show ~2% gains on 453.povray/ > 511.povray_r, all don't have any remarkable degradations. Nice :-) What does it do to geomean, is that in the right direction as well? As a follow-up, vec_promote_demote is costed similarly higher for VSX than for other things, it might help to change that one as well? > This patch is to lower vec_perm vectorization cost for all > non Power7 VSX architecture (currently Power8 and Power9). Okay for trunk with the comment fixed (just say p7 has only one permute unit?), and assuming geomean is fine too. Thanks! Segher
