src/compiler/nir/nir_opt_intrinsics.c

   1 /*
   2  * Copyright © 2017 Intel Corporation
   3  *
   4  * Permission is hereby granted, free of charge, to any person obtaining a
   5  * copy of this software and associated documentation files (the "Software"),
   6  * to deal in the Software without restriction, including without limitation
   7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   8  * and/or sell copies of the Software, and to permit persons to whom the
   9  * Software is furnished to do so, subject to the following conditions:
  10  *
  11  * The above copyright notice and this permission notice (including the next
  12  * paragraph) shall be included in all copies or substantial portions of the
  13  * Software.
  14  *
  15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  18  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  19  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  20  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  21  * IN THE SOFTWARE.
  22  */
  23
  24 #include "nir.h"
  25 #include "nir_builder.h"
  26
  27 /**
  28  * \file nir_opt_intrinsics.c
  29  */
  30
  31 static nir_ssa_def *
  32 high_subgroup_mask(nir_builder *b,
  33                    nir_ssa_def *count,
  34                    uint64_t base_mask)
  35 {
  36    /* group_mask could probably be calculated more efficiently but we want to
  37     * be sure not to shift by 64 if the subgroup size is 64 because the GLSL
  38     * shift operator is undefined in that case. In any case if we were worried
  39     * about efficency this should probably be done further down because the
  40     * subgroup size is likely to be known at compile time.
  41     */
  42    nir_ssa_def *subgroup_size = nir_load_subgroup_size(b);
  43    nir_ssa_def *all_bits = nir_imm_int64(b, ~0ull);
  44    nir_ssa_def *shift = nir_isub(b, nir_imm_int(b, 64), subgroup_size);
  45    nir_ssa_def *group_mask = nir_ushr(b, all_bits, shift);
  46    nir_ssa_def *higher_bits = nir_ishl(b, nir_imm_int64(b, base_mask), count);
  47
  48    return nir_iand(b, higher_bits, group_mask);
  49 }
  50
  51 static bool
  52 opt_intrinsics_impl(nir_function_impl *impl)
  53 {
  54    nir_builder b;
  55    nir_builder_init(&b, impl);
  56    bool progress = false;
  57
  58    nir_foreach_block(block, impl) {
  59       nir_foreach_instr_safe(instr, block) {
  60          if (instr->type != nir_instr_type_intrinsic)
  61             continue;
  62
  63          nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr);
  64          nir_ssa_def *replacement = NULL;
  65          b.cursor = nir_before_instr(instr);
  66
  67          switch (intrin->intrinsic) {
  68          case nir_intrinsic_vote_any:
  69          case nir_intrinsic_vote_all: {
  70             nir_const_value *val = nir_src_as_const_value(intrin->src[0]);
  71             if (!val && !b.shader->options->lower_vote_trivial)
  72                continue;
  73
  74             replacement = nir_ssa_for_src(&b, intrin->src[0], 1);
  75             break;
  76          }
  77          case nir_intrinsic_vote_eq: {
  78             nir_const_value *val = nir_src_as_const_value(intrin->src[0]);
  79             if (!val && !b.shader->options->lower_vote_trivial)
  80                continue;
  81
  82             replacement = nir_imm_int(&b, NIR_TRUE);
  83             break;
  84          }
  85          case nir_intrinsic_ballot: {
  86             assert(b.shader->options->max_subgroup_size != 0);
  87             if (b.shader->options->max_subgroup_size > 32 ||
  88                 intrin->dest.ssa.bit_size <= 32)
  89                continue;
  90
  91             nir_intrinsic_instr *ballot =
  92                nir_intrinsic_instr_create(b.shader, nir_intrinsic_ballot);
  93             nir_ssa_dest_init(&ballot->instr, &ballot->dest, 1, 32, NULL);
  94             nir_src_copy(&ballot->src[0], &intrin->src[0], ballot);
  95
  96             nir_builder_instr_insert(&b, &ballot->instr);
  97
  98             replacement = nir_pack_64_2x32_split(&b,
  99                                                  &ballot->dest.ssa,
 100                                                  nir_imm_int(&b, 0));
 101             break;
 102          }
 103          case nir_intrinsic_load_subgroup_eq_mask:
 104          case nir_intrinsic_load_subgroup_ge_mask:
 105          case nir_intrinsic_load_subgroup_gt_mask:
 106          case nir_intrinsic_load_subgroup_le_mask:
 107          case nir_intrinsic_load_subgroup_lt_mask: {
 108             if (!b.shader->options->lower_subgroup_masks)
 109                break;
 110
 111             nir_ssa_def *count = nir_load_subgroup_invocation(&b);
 112
 113             switch (intrin->intrinsic) {
 114             case nir_intrinsic_load_subgroup_eq_mask:
 115                replacement = nir_ishl(&b, nir_imm_int64(&b, 1ull), count);
 116                break;
 117             case nir_intrinsic_load_subgroup_ge_mask:
 118                replacement = high_subgroup_mask(&b, count, ~0ull);
 119                break;
 120             case nir_intrinsic_load_subgroup_gt_mask:
 121                replacement = high_subgroup_mask(&b, count, ~1ull);
 122                break;
 123             case nir_intrinsic_load_subgroup_le_mask:
 124                replacement = nir_inot(&b, nir_ishl(&b, nir_imm_int64(&b, ~1ull), count));
 125                break;
 126             case nir_intrinsic_load_subgroup_lt_mask:
 127                replacement = nir_inot(&b, nir_ishl(&b, nir_imm_int64(&b, ~0ull), count));
 128                break;
 129             default:
 130                unreachable("you seriously can't tell this is unreachable?");
 131             }
 132             break;
 133          }
 134          default:
 135             break;
 136          }
 137
 138          if (!replacement)
 139             continue;
 140
 141          nir_ssa_def_rewrite_uses(&intrin->dest.ssa,
 142                                   nir_src_for_ssa(replacement));
 143          nir_instr_remove(instr);
 144          progress = true;
 145       }
 146    }
 147
 148    return progress;
 149 }
 150
 151 bool
 152 nir_opt_intrinsics(nir_shader *shader)
 153 {
 154    bool progress = false;
 155
 156    nir_foreach_function(function, shader) {
 157       if (!function->impl)
 158          continue;
 159
 160       if (opt_intrinsics_impl(function->impl)) {
 161          progress = true;
 162          nir_metadata_preserve(function->impl, nir_metadata_block_index |
 163                                                nir_metadata_dominance);
 164       }
 165    }
 166
 167    return progress;
 168 }