On Mon, Oct 15, 2018 at 8:41 PM Jason Ekstrand <ja...@jlekstrand.net> wrote: > > On Mon, Oct 15, 2018 at 1:39 PM Ian Romanick <i...@freedesktop.org> wrote: >> >> On 10/14/2018 03:58 PM, Jason Ekstrand wrote: >> > On October 14, 2018 17:12:34 Matt Turner <matts...@gmail.com> wrote: >> >> +static nir_ssa_def * >> >> +lower_iabs64(nir_builder *b, nir_ssa_def *x) >> >> +{ >> >> + nir_ssa_def *x_hi = nir_unpack_64_2x32_split_y(b, x); >> >> + nir_ssa_def *x_is_neg = nir_ilt(b, x_hi, nir_imm_int(b, 0)); >> >> + return nir_bcsel(b, x_is_neg, lower_ineg64(b, x), x); >> > >> > lower_bcsel? Or, since we're depending on this running multiple times, >> > just nir_ineg? I go back and forth on whether a pass like this should >> > run in a loop or be smart enough to lower intermediate bits on the fly. >> > We should probably pick one. >> >> In principle, I agree. I've been bitten a couple times by lowering >> passes that generate other things that need to be lowered on some >> platforms (that I didn't test). In this case, I think the loop is the >> right answer since each operation is lowered by a separate flag. > > > That's the easy answer, certainly. The other option is to have every lowered > thing builder check the flag and conditionally do the lowering. That's > annoying and hard to get right so a loop is probably best for now.
Couldn't you just have the builder be right after the instruction, instead of before it, and make the outer loop use a non-safe iterator so that it will immediately run over the instructions generated? Doing another pass over the whole shader is usually a little expensive. > > --Jason > _______________________________________________ > mesa-dev mailing list > mesa-dev@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/mesa-dev _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/mesa-dev