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 bool deref_used_for_not_store(nir_deref_instr * deref)31 deref_used_for_not_store(nir_deref_instr *deref) 32 { 33 nir_foreach_use(src, &deref->def) { 34 switch (nir_src_parent_instr(src)->type) { 35 case nir_instr_type_deref: 36 if (deref_used_for_not_store(nir_instr_as_deref(nir_src_parent_instr(src)))) 37 return true; 38 break; 39 40 case nir_instr_type_intrinsic: { 41 nir_intrinsic_instr *intrin = 42 nir_instr_as_intrinsic(nir_src_parent_instr(src)); 43 /* The first source of copy and store intrinsics is the deref to 44 * write. Don't record those. 45 */ 46 if ((intrin->intrinsic != nir_intrinsic_store_deref && 47 intrin->intrinsic != nir_intrinsic_copy_deref) || 48 src != &intrin->src[0]) 49 return true; 50 break; 51 } 52 53 default: 54 /* If it's used by any other instruction type (most likely a texture 55 * or call instruction), consider it used. 56 */ 57 return true; 58 } 59 } 60 61 return false; 62 } 63 64 static void add_var_use_deref(nir_deref_instr * deref,struct set * live)65 add_var_use_deref(nir_deref_instr *deref, struct set *live) 66 { 67 if (deref->deref_type != nir_deref_type_var) 68 return; 69 70 /* Since these local variables don't escape the shader, writing doesn't 71 * make them live. Only keep them if they are used by some intrinsic. 72 */ 73 if ((deref->var->data.mode & (nir_var_function_temp | 74 nir_var_shader_temp)) && 75 !deref_used_for_not_store(deref)) 76 return; 77 78 /* 79 * Shared memory blocks (interface type) alias each other, so be 80 * conservative in that case. 81 */ 82 if ((deref->var->data.mode & nir_var_mem_shared) && 83 !glsl_type_is_interface(deref->var->type) && 84 !deref_used_for_not_store(deref)) 85 return; 86 87 nir_variable *var = deref->var; 88 do { 89 _mesa_set_add(live, var); 90 /* Also mark the chain of variables used to initialize it. */ 91 var = var->pointer_initializer; 92 } while (var); 93 } 94 95 static void add_var_use_shader(nir_shader * shader,struct set * live,nir_variable_mode modes)96 add_var_use_shader(nir_shader *shader, struct set *live, nir_variable_mode modes) 97 { 98 nir_foreach_function_impl(impl, shader) { 99 nir_foreach_block(block, impl) { 100 nir_foreach_instr(instr, block) { 101 if (instr->type == nir_instr_type_deref) 102 add_var_use_deref(nir_instr_as_deref(instr), live); 103 } 104 } 105 } 106 } 107 108 static void remove_dead_var_writes(nir_shader * shader)109 remove_dead_var_writes(nir_shader *shader) 110 { 111 nir_foreach_function_impl(impl, shader) { 112 nir_foreach_block(block, impl) { 113 nir_foreach_instr_safe(instr, block) { 114 switch (instr->type) { 115 case nir_instr_type_deref: { 116 nir_deref_instr *deref = nir_instr_as_deref(instr); 117 if (deref->deref_type == nir_deref_type_cast && 118 !nir_deref_instr_parent(deref)) 119 continue; 120 121 nir_variable_mode parent_modes; 122 if (deref->deref_type == nir_deref_type_var) 123 parent_modes = deref->var->data.mode; 124 else 125 parent_modes = nir_deref_instr_parent(deref)->modes; 126 127 /* If the parent mode is 0, then it references a dead variable. 128 * Flag this deref as dead and remove it. 129 */ 130 if (parent_modes == 0) { 131 deref->modes = 0; 132 nir_instr_remove(&deref->instr); 133 } 134 break; 135 } 136 137 case nir_instr_type_intrinsic: { 138 nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr); 139 if (intrin->intrinsic != nir_intrinsic_copy_deref && 140 intrin->intrinsic != nir_intrinsic_store_deref) 141 break; 142 143 if (nir_src_as_deref(intrin->src[0])->modes == 0) 144 nir_instr_remove(instr); 145 break; 146 } 147 148 default: 149 break; /* Nothing to do */ 150 } 151 } 152 } 153 } 154 } 155 156 static bool remove_dead_vars(struct exec_list * var_list,nir_variable_mode modes,struct set * live,const nir_remove_dead_variables_options * opts)157 remove_dead_vars(struct exec_list *var_list, nir_variable_mode modes, 158 struct set *live, const nir_remove_dead_variables_options *opts) 159 { 160 bool progress = false; 161 162 nir_foreach_variable_in_list_safe(var, var_list) { 163 if (!(var->data.mode & modes)) 164 continue; 165 166 if (opts && opts->can_remove_var && 167 !opts->can_remove_var(var, opts->can_remove_var_data)) 168 continue; 169 170 struct set_entry *entry = _mesa_set_search(live, var); 171 if (entry == NULL) { 172 /* Mark this variable as dead by setting the mode to 0 */ 173 var->data.mode = 0; 174 exec_node_remove(&var->node); 175 progress = true; 176 } 177 } 178 179 return progress; 180 } 181 182 bool nir_remove_dead_variables(nir_shader * shader,nir_variable_mode modes,const nir_remove_dead_variables_options * opts)183 nir_remove_dead_variables(nir_shader *shader, nir_variable_mode modes, 184 const nir_remove_dead_variables_options *opts) 185 { 186 bool progress = false; 187 struct set *live = _mesa_pointer_set_create(NULL); 188 189 add_var_use_shader(shader, live, modes); 190 191 if (modes & ~nir_var_function_temp) { 192 progress = remove_dead_vars(&shader->variables, modes, 193 live, opts) || 194 progress; 195 } 196 197 if (modes & nir_var_function_temp) { 198 nir_foreach_function_impl(impl, shader) { 199 if (remove_dead_vars(&impl->locals, 200 nir_var_function_temp, 201 live, opts)) 202 progress = true; 203 } 204 } 205 206 _mesa_set_destroy(live, NULL); 207 208 nir_foreach_function_impl(impl, shader) { 209 if (progress) { 210 remove_dead_var_writes(shader); 211 nir_metadata_preserve(impl, nir_metadata_control_flow); 212 } else { 213 nir_metadata_preserve(impl, nir_metadata_all); 214 } 215 } 216 217 return progress; 218 } 219