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/* SSA-based mark-and-sweep dead code elimination */ 31 32typedef struct { 33 struct exec_node node; 34 nir_instr *instr; 35} worklist_elem; 36 37static void 38worklist_push(struct exec_list *worklist, nir_instr *instr) 39{ 40 worklist_elem *elem = ralloc(worklist, worklist_elem); 41 elem->instr = instr; 42 instr->pass_flags = 1; 43 exec_list_push_tail(worklist, &elem->node); 44} 45 46static nir_instr * 47worklist_pop(struct exec_list *worklist) 48{ 49 struct exec_node *node = exec_list_pop_head(worklist); 50 worklist_elem *elem = exec_node_data(worklist_elem, node, node); 51 return elem->instr; 52} 53 54static bool 55mark_live_cb(nir_src *src, void *_state) 56{ 57 struct exec_list *worklist = (struct exec_list *) _state; 58 59 if (src->is_ssa && !src->ssa->parent_instr->pass_flags) { 60 worklist_push(worklist, src->ssa->parent_instr); 61 } 62 63 return true; 64} 65 66static void 67init_instr(nir_instr *instr, struct exec_list *worklist) 68{ 69 nir_alu_instr *alu_instr; 70 nir_intrinsic_instr *intrin_instr; 71 nir_tex_instr *tex_instr; 72 73 /* We use the pass_flags to store the live/dead information. In DCE, we 74 * just treat it as a zero/non-zero boolean for whether or not the 75 * instruction is live. 76 */ 77 instr->pass_flags = 0; 78 79 switch (instr->type) { 80 case nir_instr_type_call: 81 case nir_instr_type_jump: 82 worklist_push(worklist, instr); 83 break; 84 85 case nir_instr_type_alu: 86 alu_instr = nir_instr_as_alu(instr); 87 if (!alu_instr->dest.dest.is_ssa) 88 worklist_push(worklist, instr); 89 break; 90 91 case nir_instr_type_intrinsic: 92 intrin_instr = nir_instr_as_intrinsic(instr); 93 if (nir_intrinsic_infos[intrin_instr->intrinsic].flags & 94 NIR_INTRINSIC_CAN_ELIMINATE) { 95 if (nir_intrinsic_infos[intrin_instr->intrinsic].has_dest && 96 !intrin_instr->dest.is_ssa) { 97 worklist_push(worklist, instr); 98 } 99 } else { 100 worklist_push(worklist, instr); 101 } 102 break; 103 104 case nir_instr_type_tex: 105 tex_instr = nir_instr_as_tex(instr); 106 if (!tex_instr->dest.is_ssa) 107 worklist_push(worklist, instr); 108 break; 109 110 default: 111 break; 112 } 113} 114 115static bool 116init_block(nir_block *block, struct exec_list *worklist) 117{ 118 nir_foreach_instr(instr, block) 119 init_instr(instr, worklist); 120 121 nir_if *following_if = nir_block_get_following_if(block); 122 if (following_if) { 123 if (following_if->condition.is_ssa && 124 !following_if->condition.ssa->parent_instr->pass_flags) 125 worklist_push(worklist, following_if->condition.ssa->parent_instr); 126 } 127 128 return true; 129} 130 131static bool 132nir_opt_dce_impl(nir_function_impl *impl) 133{ 134 struct exec_list *worklist = rzalloc(NULL, struct exec_list); 135 exec_list_make_empty(worklist); 136 137 nir_foreach_block(block, impl) { 138 init_block(block, worklist); 139 } 140 141 while (!exec_list_is_empty(worklist)) { 142 nir_instr *instr = worklist_pop(worklist); 143 nir_foreach_src(instr, mark_live_cb, worklist); 144 } 145 146 ralloc_free(worklist); 147 148 bool progress = false; 149 150 nir_foreach_block(block, impl) { 151 nir_foreach_instr_safe(instr, block) { 152 if (!instr->pass_flags) { 153 nir_instr_remove(instr); 154 progress = true; 155 } 156 } 157 } 158 159 if (progress) 160 nir_metadata_preserve(impl, nir_metadata_block_index | 161 nir_metadata_dominance); 162 163 return progress; 164} 165 166bool 167nir_opt_dce(nir_shader *shader) 168{ 169 bool progress = false; 170 nir_foreach_function(function, shader) { 171 if (function->impl && nir_opt_dce_impl(function->impl)) 172 progress = true; 173 } 174 175 return progress; 176} 177