src/glsl/nir/nir_lower_atomics.c

   1 /*
   2  * Copyright © 2014 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  * Authors:
  24  *    Connor Abbott (cwabbott0@gmail.com)
  25  *
  26  */
  27
  28 #include "nir.h"
  29 #include "main/config.h"
  30 #include <assert.h>
  31
  32 /*
  33  * replace atomic counter intrinsics that use a variable with intrinsics
  34  * that directly store the buffer index and byte offset
  35  */
  36
  37 static void
  38 lower_instr(nir_intrinsic_instr *instr, nir_function_impl *impl)
  39 {
  40    nir_intrinsic_op op;
  41    switch (instr->intrinsic) {
  42    case nir_intrinsic_atomic_counter_read_var:
  43       op = nir_intrinsic_atomic_counter_read;
  44       break;
  45
  46    case nir_intrinsic_atomic_counter_inc_var:
  47       op = nir_intrinsic_atomic_counter_inc;
  48       break;
  49
  50    case nir_intrinsic_atomic_counter_dec_var:
  51       op = nir_intrinsic_atomic_counter_dec;
  52       break;
  53
  54    default:
  55       return;
  56    }
  57
  58    if (instr->variables[0]->var->data.mode != nir_var_uniform)
  59       return; /* atomics passed as function arguments can't be lowered */
  60
  61    void *mem_ctx = ralloc_parent(instr);
  62
  63    nir_intrinsic_instr *new_instr = nir_intrinsic_instr_create(mem_ctx, op);
  64    new_instr->const_index[0] =
  65       (int) instr->variables[0]->var->data.atomic.buffer_index;
  66
  67    nir_load_const_instr *offset_const = nir_load_const_instr_create(mem_ctx, 1);
  68    offset_const->value.u[0] = instr->variables[0]->var->data.atomic.offset;
  69
  70    nir_instr_insert_before(&instr->instr, &offset_const->instr);
  71
  72    nir_ssa_def *offset_def = &offset_const->def;
  73
  74    if (instr->variables[0]->deref.child != NULL) {
  75       assert(instr->variables[0]->deref.child->deref_type ==
  76              nir_deref_type_array);
  77       nir_deref_array *deref_array =
  78          nir_deref_as_array(instr->variables[0]->deref.child);
  79       assert(deref_array->deref.child == NULL);
  80
  81       offset_const->value.u[0] +=
  82          deref_array->base_offset * ATOMIC_COUNTER_SIZE;
  83
  84       if (deref_array->deref_array_type == nir_deref_array_type_indirect) {
  85          nir_load_const_instr *atomic_counter_size =
  86                nir_load_const_instr_create(mem_ctx, 1);
  87          atomic_counter_size->value.u[0] = ATOMIC_COUNTER_SIZE;
  88          nir_instr_insert_before(&instr->instr, &atomic_counter_size->instr);
  89
  90          nir_alu_instr *mul = nir_alu_instr_create(mem_ctx, nir_op_imul);
  91          nir_ssa_dest_init(&mul->instr, &mul->dest.dest, 1, NULL);
  92          mul->dest.write_mask = 0x1;
  93          nir_src_copy(&mul->src[0].src, &deref_array->indirect, mem_ctx);
  94          mul->src[1].src.is_ssa = true;
  95          mul->src[1].src.ssa = &atomic_counter_size->def;
  96          nir_instr_insert_before(&instr->instr, &mul->instr);
  97
  98          nir_alu_instr *add = nir_alu_instr_create(mem_ctx, nir_op_iadd);
  99          nir_ssa_dest_init(&add->instr, &add->dest.dest, 1, NULL);
 100          add->dest.write_mask = 0x1;
 101          add->src[0].src.is_ssa = true;
 102          add->src[0].src.ssa = &mul->dest.dest.ssa;
 103          add->src[1].src.is_ssa = true;
 104          add->src[1].src.ssa = &offset_const->def;
 105          nir_instr_insert_before(&instr->instr, &add->instr);
 106
 107          offset_def = &add->dest.dest.ssa;
 108       }
 109    }
 110
 111    new_instr->src[0].is_ssa = true;
 112    new_instr->src[0].ssa = offset_def;;
 113
 114    if (instr->dest.is_ssa) {
 115       nir_ssa_dest_init(&new_instr->instr, &new_instr->dest,
 116                         instr->dest.ssa.num_components, NULL);
 117       nir_ssa_def_rewrite_uses(&instr->dest.ssa,
 118                                nir_src_for_ssa(&new_instr->dest.ssa),
 119                                mem_ctx);
 120    } else {
 121       nir_dest_copy(&new_instr->dest, &instr->dest, mem_ctx);
 122    }
 123
 124    nir_instr_insert_before(&instr->instr, &new_instr->instr);
 125    nir_instr_remove(&instr->instr);
 126 }
 127
 128 static bool
 129 lower_block(nir_block *block, void *state)
 130 {
 131    nir_foreach_instr_safe(block, instr) {
 132       if (instr->type == nir_instr_type_intrinsic)
 133          lower_instr(nir_instr_as_intrinsic(instr), state);
 134    }
 135
 136    return true;
 137 }
 138
 139 void
 140 nir_lower_atomics(nir_shader *shader)
 141 {
 142    nir_foreach_overload(shader, overload) {
 143       if (overload->impl) {
 144          nir_foreach_block(overload->impl, lower_block, overload->impl);
 145          nir_metadata_preserve(overload->impl, nir_metadata_block_index |
 146                                                nir_metadata_dominance);
 147       }
 148    }
 149 }