<div dir="ltr"><div class="gmail_extra"><div class="gmail_quote">On Sat, Mar 10, 2018 at 10:18 AM, Jason Ekstrand <<a href="mailto:jason@jlekstrand.net" target="_blank">jason@jlekstrand.net</a>> wrote: <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">This is based heavily on 97f10934edf8ac, "ac/nir: Add vote_ieq/vote_feq lowering pass." from Bas Nieuwenhuizen. This version is a bit more general since it's in common code. It also properly handles NaN due to not flipping the comparison for floats. --- src/compiler/nir/nir.h | 1 + src/compiler/nir/nir_lower_subgroups.c | 48 ++++++++++++++++++++++++++++++++++ 2 files changed, 49 insertions(+) diff --git a/src/compiler/nir/nir.h b/src/compiler/nir/nir.h index 5b28c72..40b1028 100644 --- a/src/compiler/nir/nir.h +++ b/src/compiler/nir/nir.h @@ -2557,6 +2557,7 @@ typedef struct nir_lower_subgroups_options { uint8_t ballot_bit_size; bool lower_to_scalar:1; bool lower_vote_trivial:1; + bool lower_vote_eq_to_ballot:1; bool lower_subgroup_masks:1; bool lower_shuffle:1; bool lower_quad:1; diff --git a/src/compiler/nir/nir_lower_subgroups.c b/src/compiler/nir/nir_lower_subgroups.c index f18ad00..e633ffe 100644 --- a/src/compiler/nir/nir_lower_subgroups.c +++ b/src/compiler/nir/nir_lower_subgroups.c @@ -142,6 +142,51 @@ lower_vote_eq_to_scalar(nir_builder *b, nir_intrinsic_instr *intrin) } static nir_ssa_def * +lower_vote_eq_to_ballot(nir_builder *b, nir_intrinsic_instr *intrin, + const nir_lower_subgroups_options *options) +{ + assert(intrin->src[0].is_ssa); + nir_ssa_def *value = intrin->src[0].ssa; + + /* We have to implicitly lower to scalar */ + nir_ssa_def *all_eq = NULL; + for (unsigned i = 0; i < intrin->num_components; i++) { + nir_intrinsic_instr *rfi = + nir_intrinsic_instr_create(b->shader, + nir_intrinsic_read_first_invocation); + nir_ssa_dest_init(&rfi->instr, &rfi->dest, + 1, intrin->dest.ssa.bit_size, NULL); + rfi->num_components = intrin->dest.ssa.num_components; </blockquote><div> </div><div>This should be 1 component. copy+paste and/or rebase fail. Fixed locally. </div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"> + rfi->src[0] = nir_src_for_ssa(nir_channel(b, value, i)); + nir_builder_instr_insert(b, &rfi->instr); + + nir_ssa_def *is_eq; + if (intrin->intrinsic == nir_intrinsic_vote_feq) { + is_eq = nir_feq(b, &rfi->dest.ssa, intrin->src[0].ssa); + } else { + is_eq = nir_ieq(b, &rfi->dest.ssa, intrin->src[0].ssa); + } + + if (all_eq == NULL) { + all_eq = is_eq; + } else { + all_eq = nir_iand(b, all_eq, is_eq); + } + } + + nir_intrinsic_instr *ballot = + nir_intrinsic_instr_create(b->shader, nir_intrinsic_ballot); + nir_ssa_dest_init(&ballot->instr, &ballot->dest, + 1, options->ballot_bit_size, NULL); + ballot->num_components = 1; + ballot->src[0] = nir_src_for_ssa(nir_inot(b, all_eq)); + nir_builder_instr_insert(b, &ballot->instr); + + return nir_ieq(b, &ballot->dest.ssa, + nir_imm_intN_t(b, 0, options->ballot_bit_size)); +} + +static nir_ssa_def * lower_shuffle(nir_builder *b, nir_intrinsic_instr *intrin, bool lower_to_scalar) { @@ -219,6 +264,9 @@ lower_subgroups_intrin(nir_builder *b, nir_intrinsic_instr *intrin, if (options->lower_vote_trivial) return nir_imm_int(b, NIR_TRUE); + if (options->lower_vote_eq_to_ballot) + return lower_vote_eq_to_ballot(b, intrin, options); + if (options->lower_to_scalar && intrin->num_components > 1) return lower_vote_eq_to_scalar(b, intrin); break; -- 2.5.0.400.gff86faf </blockquote></div> </div></div>