src/compiler/nir/nir_remove_dead_variables.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
  30 static void
  31 add_var_use_intrinsic(nir_intrinsic_instr *instr, struct set *live)
  32 {
  33    unsigned num_vars = nir_intrinsic_infos[instr->intrinsic].num_variables;
  34    for (unsigned i = 0; i < num_vars; i++) {
  35       nir_variable *var = instr->variables[i]->var;
  36       _mesa_set_add(live, var);
  37    }
  38 }
  39
  40 static void
  41 add_var_use_call(nir_call_instr *instr, struct set *live)
  42 {
  43    if (instr->return_deref != NULL) {
  44       nir_variable *var = instr->return_deref->var;
  45       _mesa_set_add(live, var);
  46    }
  47
  48    for (unsigned i = 0; i < instr->num_params; i++) {
  49       nir_variable *var = instr->params[i]->var;
  50       _mesa_set_add(live, var);
  51    }
  52 }
  53
  54 static void
  55 add_var_use_tex(nir_tex_instr *instr, struct set *live)
  56 {
  57    if (instr->texture != NULL) {
  58       nir_variable *var = instr->texture->var;
  59       _mesa_set_add(live, var);
  60    }
  61
  62    if (instr->sampler != NULL) {
  63       nir_variable *var = instr->sampler->var;
  64       _mesa_set_add(live, var);
  65    }
  66 }
  67
  68 static bool
  69 add_var_use_block(nir_block *block, void *state)
  70 {
  71    struct set *live = state;
  72
  73    nir_foreach_instr(block, instr) {
  74       switch(instr->type) {
  75       case nir_instr_type_intrinsic:
  76          add_var_use_intrinsic(nir_instr_as_intrinsic(instr), live);
  77          break;
  78
  79       case nir_instr_type_call:
  80          add_var_use_call(nir_instr_as_call(instr), live);
  81          break;
  82
  83       case nir_instr_type_tex:
  84          add_var_use_tex(nir_instr_as_tex(instr), live);
  85          break;
  86
  87       default:
  88          break;
  89       }
  90    }
  91
  92    return true;
  93 }
  94
  95 static void
  96 add_var_use_shader(nir_shader *shader, struct set *live)
  97 {
  98    nir_foreach_function(shader, function) {
  99       if (function->impl) {
 100          nir_foreach_block(function->impl, add_var_use_block, live);
 101       }
 102    }
 103 }
 104
 105 static bool
 106 remove_dead_vars(struct exec_list *var_list, struct set *live)
 107 {
 108    bool progress = false;
 109
 110    foreach_list_typed_safe(nir_variable, var, node, var_list) {
 111       struct set_entry *entry = _mesa_set_search(live, var);
 112       if (entry == NULL) {
 113          exec_node_remove(&var->node);
 114          ralloc_free(var);
 115          progress = true;
 116       }
 117    }
 118
 119    return progress;
 120 }
 121
 122 bool
 123 nir_remove_dead_variables(nir_shader *shader, nir_variable_mode mode)
 124 {
 125    bool progress = false;
 126    struct set *live =
 127       _mesa_set_create(NULL, _mesa_hash_pointer, _mesa_key_pointer_equal);
 128
 129    add_var_use_shader(shader, live);
 130
 131    if (mode == nir_var_uniform || mode == nir_var_all)
 132       progress = remove_dead_vars(&shader->uniforms, live) || progress;
 133
 134    if (mode == nir_var_shader_in || mode == nir_var_all)
 135       progress = remove_dead_vars(&shader->inputs, live) || progress;
 136
 137    if (mode == nir_var_shader_out || mode == nir_var_all)
 138       progress = remove_dead_vars(&shader->outputs, live) || progress;
 139
 140    if (mode == nir_var_global || mode == nir_var_all)
 141       progress = remove_dead_vars(&shader->globals, live) || progress;
 142
 143    if (mode == nir_var_system_value || mode == nir_var_all)
 144       progress = remove_dead_vars(&shader->system_values, live) || progress;
 145
 146    if (mode == nir_var_local || mode == nir_var_all) {
 147       nir_foreach_function(shader, function) {
 148          if (function->impl) {
 149             if (remove_dead_vars(&function->impl->locals, live)) {
 150                nir_metadata_preserve(function->impl, nir_metadata_block_index |
 151                                                      nir_metadata_dominance |
 152                                                      nir_metadata_live_ssa_defs);
 153                progress = true;
 154             }
 155          }
 156       }
 157    }
 158
 159    _mesa_set_destroy(live, NULL);
 160    return progress;
 161 }