1 /* 2 * Copyright 2015 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 * Jason Ekstrand <jason (at) jlekstrand.net> 25 */ 26 27 #include "brw_nir.h" 28 29 /* 30 * This file implements an analysis pass that determines when we have to do 31 * a boolean resolve on Gen <= 5. Instructions that need a boolean resolve 32 * will have the booleans portion of the instr->pass_flags field set to 33 * BRW_NIR_BOOLEAN_NEEDS_RESOLVE. 34 */ 35 36 37 /** Returns the resolve status for the given source 38 * 39 * If the source has a parent instruction then the resolve status is the 40 * status of the parent instruction. If the source does not have a parent 41 * instruction then we don't know so we return NON_BOOLEAN. 42 */ 43 static uint8_t 44 get_resolve_status_for_src(nir_src *src) 45 { 46 if (src->is_ssa) { 47 nir_instr *src_instr = src->ssa->parent_instr; 48 uint8_t resolve_status = src_instr->pass_flags & BRW_NIR_BOOLEAN_MASK; 49 50 /* If the source instruction needs resolve, then from the perspective 51 * of the user, it's a true boolean. 52 */ 53 if (resolve_status == BRW_NIR_BOOLEAN_NEEDS_RESOLVE) 54 resolve_status = BRW_NIR_BOOLEAN_NO_RESOLVE; 55 return resolve_status; 56 } else { 57 return BRW_NIR_NON_BOOLEAN; 58 } 59 } 60 61 /** Marks the given source as needing a resolve 62 * 63 * If the given source corresponds to an unresolved boolean it marks it as 64 * needing a resolve. Otherwise, we leave it alone. 65 */ 66 static bool 67 src_mark_needs_resolve(nir_src *src, void *void_state) 68 { 69 if (src->is_ssa) { 70 nir_instr *src_instr = src->ssa->parent_instr; 71 uint8_t resolve_status = src_instr->pass_flags & BRW_NIR_BOOLEAN_MASK; 72 73 /* If the source instruction is unresolved, then mark it as needing 74 * to be resolved. 75 */ 76 if (resolve_status == BRW_NIR_BOOLEAN_UNRESOLVED) { 77 src_instr->pass_flags &= ~BRW_NIR_BOOLEAN_MASK; 78 src_instr->pass_flags |= BRW_NIR_BOOLEAN_NEEDS_RESOLVE; 79 } 80 81 } 82 83 return true; 84 } 85 86 static bool 87 analyze_boolean_resolves_block(nir_block *block) 88 { 89 nir_foreach_instr(instr, block) { 90 switch (instr->type) { 91 case nir_instr_type_alu: { 92 /* For ALU instructions, the resolve status is handled in a 93 * three-step process. 94 * 95 * 1) Look at the instruction type and sources and determine if it 96 * can be left unresolved. 97 * 98 * 2) Look at the destination and see if we have to resolve 99 * anyway. (This is the case if this instruction is not the 100 * only instruction writing to a given register.) 101 * 102 * 3) If the instruction has a resolve status other than 103 * BOOL_UNRESOLVED or BOOL_NEEDS_RESOLVE then we walk through 104 * the sources and ensure that they are also resolved. This 105 * ensures that we don't end up with any stray unresolved 106 * booleans going into ADDs or something like that. 107 */ 108 109 uint8_t resolve_status; 110 nir_alu_instr *alu = nir_instr_as_alu(instr); 111 switch (alu->op) { 112 case nir_op_ball_fequal2: 113 case nir_op_ball_iequal2: 114 case nir_op_ball_fequal3: 115 case nir_op_ball_iequal3: 116 case nir_op_ball_fequal4: 117 case nir_op_ball_iequal4: 118 case nir_op_bany_fnequal2: 119 case nir_op_bany_inequal2: 120 case nir_op_bany_fnequal3: 121 case nir_op_bany_inequal3: 122 case nir_op_bany_fnequal4: 123 case nir_op_bany_inequal4: 124 /* These are only implemented by the vec4 backend and its 125 * implementation emits resolved booleans. At some point in the 126 * future, this may change and we'll have to remove some of the 127 * above cases. 128 */ 129 resolve_status = BRW_NIR_BOOLEAN_NO_RESOLVE; 130 break; 131 132 case nir_op_imov: 133 case nir_op_inot: 134 /* This is a single-source instruction. Just copy the resolve 135 * status from the source. 136 */ 137 resolve_status = get_resolve_status_for_src(&alu->src[0].src); 138 break; 139 140 case nir_op_iand: 141 case nir_op_ior: 142 case nir_op_ixor: { 143 uint8_t src0_status = get_resolve_status_for_src(&alu->src[0].src); 144 uint8_t src1_status = get_resolve_status_for_src(&alu->src[1].src); 145 146 if (src0_status == src1_status) { 147 resolve_status = src0_status; 148 } else if (src0_status == BRW_NIR_NON_BOOLEAN || 149 src1_status == BRW_NIR_NON_BOOLEAN) { 150 /* If one of the sources is a non-boolean then the whole 151 * thing is a non-boolean. 152 */ 153 resolve_status = BRW_NIR_NON_BOOLEAN; 154 } else { 155 /* At this point one of them is a true boolean and one is a 156 * boolean that needs a resolve. We could either resolve the 157 * unresolved source or we could resolve here. If we resolve 158 * the unresolved source then we get two resolves for the price 159 * of one. Just set this one to BOOLEAN_NO_RESOLVE and we'll 160 * let the code below force a resolve on the unresolved source. 161 */ 162 resolve_status = BRW_NIR_BOOLEAN_NO_RESOLVE; 163 } 164 break; 165 } 166 167 default: 168 if (nir_alu_type_get_base_type(nir_op_infos[alu->op].output_type) == nir_type_bool) { 169 /* This instructions will turn into a CMP when we actually emit 170 * them so the result will have to be resolved before it can be 171 * used. 172 */ 173 resolve_status = BRW_NIR_BOOLEAN_UNRESOLVED; 174 175 /* Even though the destination is allowed to be left 176 * unresolved, the sources are treated as regular integers or 177 * floats so they need to be resolved. 178 */ 179 nir_foreach_src(instr, src_mark_needs_resolve, NULL); 180 } else { 181 resolve_status = BRW_NIR_NON_BOOLEAN; 182 } 183 } 184 185 /* If the destination is SSA, go ahead allow unresolved booleans. 186 * If the destination register doesn't have a well-defined parent_instr 187 * we need to resolve immediately. 188 */ 189 if (!alu->dest.dest.is_ssa && 190 resolve_status == BRW_NIR_BOOLEAN_UNRESOLVED) { 191 resolve_status = BRW_NIR_BOOLEAN_NEEDS_RESOLVE; 192 } 193 194 instr->pass_flags = (instr->pass_flags & ~BRW_NIR_BOOLEAN_MASK) | 195 resolve_status; 196 197 /* Finally, resolve sources if it's needed */ 198 switch (resolve_status) { 199 case BRW_NIR_BOOLEAN_NEEDS_RESOLVE: 200 case BRW_NIR_BOOLEAN_UNRESOLVED: 201 /* This instruction is either unresolved or we're doing the 202 * resolve here; leave the sources alone. 203 */ 204 break; 205 206 case BRW_NIR_BOOLEAN_NO_RESOLVE: 207 case BRW_NIR_NON_BOOLEAN: 208 nir_foreach_src(instr, src_mark_needs_resolve, NULL); 209 break; 210 211 default: 212 unreachable("Invalid boolean flag"); 213 } 214 215 break; 216 } 217 218 case nir_instr_type_load_const: { 219 nir_load_const_instr *load = nir_instr_as_load_const(instr); 220 221 /* For load_const instructions, it's a boolean exactly when it holds 222 * one of the values NIR_TRUE or NIR_FALSE. 223 * 224 * Since load_const instructions don't have any sources, we don't 225 * have to worry about resolving them. 226 */ 227 instr->pass_flags &= ~BRW_NIR_BOOLEAN_MASK; 228 if (load->value.u32[0] == NIR_TRUE || load->value.u32[0] == NIR_FALSE) { 229 instr->pass_flags |= BRW_NIR_BOOLEAN_NO_RESOLVE; 230 } else { 231 instr->pass_flags |= BRW_NIR_NON_BOOLEAN; 232 } 233 continue; 234 } 235 236 default: 237 /* Everything else is an unknown non-boolean value and needs to 238 * have all sources resolved. 239 */ 240 instr->pass_flags = (instr->pass_flags & ~BRW_NIR_BOOLEAN_MASK) | 241 BRW_NIR_NON_BOOLEAN; 242 nir_foreach_src(instr, src_mark_needs_resolve, NULL); 243 continue; 244 } 245 } 246 247 nir_if *following_if = nir_block_get_following_if(block); 248 if (following_if) 249 src_mark_needs_resolve(&following_if->condition, NULL); 250 251 return true; 252 } 253 254 static void 255 analyze_boolean_resolves_impl(nir_function_impl *impl) 256 { 257 nir_foreach_block(block, impl) { 258 analyze_boolean_resolves_block(block); 259 } 260 } 261 262 void 263 brw_nir_analyze_boolean_resolves(nir_shader *shader) 264 { 265 nir_foreach_function(function, shader) { 266 if (function->impl) 267 analyze_boolean_resolves_impl(function->impl); 268 } 269 } 270
