src/intel/compiler/brw_nir_lower_cs_intrinsics.c

   1 /*
   2  * Copyright (c) 2016 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 "brw_nir.h"
  25 #include "compiler/nir/nir_builder.h"
  26
  27 struct lower_intrinsics_state {
  28    nir_shader *nir;
  29    unsigned dispatch_width;
  30    nir_function_impl *impl;
  31    bool progress;
  32    nir_builder builder;
  33    unsigned local_workgroup_size;
  34 };
  35
  36 static bool
  37 lower_cs_intrinsics_convert_block(struct lower_intrinsics_state *state,
  38                                   nir_block *block)
  39 {
  40    bool progress = false;
  41    nir_builder *b = &state->builder;
  42    nir_shader *nir = state->nir;
  43
  44    nir_foreach_instr_safe(instr, block) {
  45       if (instr->type != nir_instr_type_intrinsic)
  46          continue;
  47
  48       nir_intrinsic_instr *intrinsic = nir_instr_as_intrinsic(instr);
  49
  50       b->cursor = nir_after_instr(&intrinsic->instr);
  51
  52       nir_ssa_def *sysval;
  53       switch (intrinsic->intrinsic) {
  54       case nir_intrinsic_load_local_invocation_index: {
  55          /* We construct the local invocation index from:
  56           *
  57           *    gl_LocalInvocationIndex =
  58           *       cs_thread_local_id + subgroup_invocation;
  59           */
  60          nir_ssa_def *subgroup_id;
  61          if (state->local_workgroup_size <= state->dispatch_width)
  62             subgroup_id = nir_imm_int(b, 0);
  63          else
  64             subgroup_id = nir_load_subgroup_id(b);
  65
  66          nir_ssa_def *thread_local_id =
  67             nir_imul(b, subgroup_id, nir_imm_int(b, state->dispatch_width));
  68          nir_ssa_def *channel = nir_load_subgroup_invocation(b);
  69          sysval = nir_iadd(b, channel, thread_local_id);
  70          break;
  71       }
  72
  73       case nir_intrinsic_load_subgroup_id:
  74          if (state->local_workgroup_size > 8)
  75             continue;
  76
  77          /* For small workgroup sizes, we know subgroup_id will be zero */
  78          sysval = nir_imm_int(b, 0);
  79          break;
  80
  81       case nir_intrinsic_load_num_subgroups: {
  82          unsigned local_workgroup_size =
  83             nir->info.cs.local_size[0] * nir->info.cs.local_size[1] *
  84             nir->info.cs.local_size[2];
  85          unsigned num_subgroups =
  86             DIV_ROUND_UP(local_workgroup_size, state->dispatch_width);
  87          sysval = nir_imm_int(b, num_subgroups);
  88          break;
  89       }
  90
  91       default:
  92          continue;
  93       }
  94
  95       nir_ssa_def_rewrite_uses(&intrinsic->dest.ssa, nir_src_for_ssa(sysval));
  96       nir_instr_remove(&intrinsic->instr);
  97
  98       state->progress = true;
  99    }
 100
 101    return progress;
 102 }
 103
 104 static void
 105 lower_cs_intrinsics_convert_impl(struct lower_intrinsics_state *state)
 106 {
 107    nir_builder_init(&state->builder, state->impl);
 108
 109    nir_foreach_block(block, state->impl) {
 110       lower_cs_intrinsics_convert_block(state, block);
 111    }
 112
 113    nir_metadata_preserve(state->impl,
 114                          nir_metadata_block_index | nir_metadata_dominance);
 115 }
 116
 117 bool
 118 brw_nir_lower_cs_intrinsics(nir_shader *nir,
 119                             unsigned dispatch_width)
 120 {
 121    assert(nir->info.stage == MESA_SHADER_COMPUTE);
 122
 123    bool progress = false;
 124    struct lower_intrinsics_state state;
 125    memset(&state, 0, sizeof(state));
 126    state.nir = nir;
 127    state.dispatch_width = dispatch_width;
 128    state.local_workgroup_size = nir->info.cs.local_size[0] *
 129                                 nir->info.cs.local_size[1] *
 130                                 nir->info.cs.local_size[2];
 131
 132    do {
 133       state.progress = false;
 134       nir_foreach_function(function, nir) {
 135          if (function->impl) {
 136             state.impl = function->impl;
 137             lower_cs_intrinsics_convert_impl(&state);
 138          }
 139       }
 140       progress |= state.progress;
 141    } while (state.progress);
 142
 143    return progress;
 144 }