src/glsl/nir/nir_search.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  *    Jason Ekstrand (jason@jlekstrand.net)
  25  *
  26  */
  27
  28 #include "nir_search.h"
  29
  30 struct match_state {
  31    unsigned variables_seen;
  32    nir_alu_src variables[NIR_SEARCH_MAX_VARIABLES];
  33 };
  34
  35 static bool
  36 match_expression(const nir_search_expression *expr, nir_alu_instr *instr,
  37                  unsigned num_components, const uint8_t *swizzle,
  38                  struct match_state *state);
  39
  40 static const uint8_t identity_swizzle[] = { 0, 1, 2, 3 };
  41
  42 static bool
  43 match_value(const nir_search_value *value, nir_alu_instr *instr, unsigned src,
  44             unsigned num_components, const uint8_t *swizzle,
  45             struct match_state *state)
  46 {
  47    uint8_t new_swizzle[4];
  48
  49    for (int i = 0; i < num_components; ++i)
  50       new_swizzle[i] = instr->src[src].swizzle[swizzle[i]];
  51
  52    switch (value->type) {
  53    case nir_search_value_expression:
  54       if (!instr->src[src].src.is_ssa)
  55          return false;
  56
  57       if (instr->src[src].src.ssa->parent_instr->type != nir_instr_type_alu)
  58          return false;
  59
  60       return match_expression(nir_search_value_as_expression(value),
  61                               nir_instr_as_alu(instr->src[src].src.ssa->parent_instr),
  62                               num_components, new_swizzle, state);
  63
  64    case nir_search_value_variable: {
  65       nir_search_variable *var = nir_search_value_as_variable(value);
  66
  67       if (state->variables_seen & (1 << var->variable)) {
  68          if (!nir_srcs_equal(state->variables[var->variable].src,
  69                              instr->src[src].src))
  70             return false;
  71
  72          assert(!instr->src[src].abs && !instr->src[src].negate);
  73
  74          for (int i = 0; i < num_components; ++i) {
  75             if (state->variables[var->variable].swizzle[i] != new_swizzle[i])
  76                return false;
  77          }
  78
  79          return true;
  80       } else {
  81          state->variables_seen |= (1 << var->variable);
  82          state->variables[var->variable].src = instr->src[src].src;
  83          state->variables[var->variable].abs = false;
  84          state->variables[var->variable].negate = false;
  85
  86          for (int i = 0; i < 4; ++i) {
  87             if (i < num_components)
  88                state->variables[var->variable].swizzle[i] = new_swizzle[i];
  89             else
  90                state->variables[var->variable].swizzle[i] = 0;
  91          }
  92
  93          return true;
  94       }
  95    }
  96
  97    case nir_search_value_constant: {
  98       nir_search_constant *const_val = nir_search_value_as_constant(value);
  99
 100       if (!instr->src[src].src.is_ssa)
 101          return false;
 102
 103       if (instr->src[src].src.ssa->parent_instr->type != nir_instr_type_load_const)
 104          return false;
 105
 106       nir_load_const_instr *load =
 107          nir_instr_as_load_const(instr->src[src].src.ssa->parent_instr);
 108
 109       switch (nir_op_infos[instr->op].input_types[src]) {
 110       case nir_type_float:
 111          for (unsigned i = 0; i < num_components; ++i) {
 112             if (load->value.f[new_swizzle[i]] != const_val->data.f)
 113                return false;
 114          }
 115          return true;
 116       case nir_type_int:
 117       case nir_type_unsigned:
 118       case nir_type_bool:
 119          for (unsigned i = 0; i < num_components; ++i) {
 120             if (load->value.i[new_swizzle[i]] != const_val->data.i)
 121                return false;
 122          }
 123          return true;
 124       default:
 125          unreachable("Invalid alu source type");
 126       }
 127    }
 128
 129    default:
 130       unreachable("Invalid search value type");
 131    }
 132 }
 133
 134 static bool
 135 match_expression(const nir_search_expression *expr, nir_alu_instr *instr,
 136                  unsigned num_components, const uint8_t *swizzle,
 137                  struct match_state *state)
 138 {
 139    if (instr->op != expr->opcode)
 140       return false;
 141
 142    assert(!instr->dest.saturate);
 143    assert(nir_op_infos[instr->op].num_inputs > 0);
 144
 145    /* If we have an explicitly sized destination, we can only handle the
 146     * identity swizzle.  While dot(vec3(a, b, c).zxy) is a valid
 147     * expression, we don't have the information right now to propagate that
 148     * swizzle through.  We can only properly propagate swizzles if the
 149     * instruction is vectorized.
 150     */
 151    if (nir_op_infos[instr->op].output_size != 0) {
 152       for (unsigned i = 0; i < num_components; i++) {
 153          if (swizzle[i] != i)
 154             return false;
 155       }
 156    }
 157
 158    bool matched = true;
 159    for (unsigned i = 0; i < nir_op_infos[instr->op].num_inputs; i++) {
 160       /* If the source is an explicitly sized source, then we need to reset
 161        * both the number of components and the swizzle.
 162        */
 163       if (nir_op_infos[instr->op].input_sizes[i] != 0) {
 164          num_components = nir_op_infos[instr->op].input_sizes[i];
 165          swizzle = identity_swizzle;
 166       }
 167
 168       if (!match_value(expr->srcs[i], instr, i, num_components,
 169                        swizzle, state)) {
 170          matched = false;
 171          break;
 172       }
 173    }
 174
 175    if (matched)
 176       return true;
 177
 178    if (nir_op_infos[instr->op].num_inputs == 2 &&
 179        (nir_op_infos[instr->op].algebraic_properties & NIR_OP_IS_COMMUTATIVE)) {
 180       if (!match_value(expr->srcs[0], instr, 1, num_components,
 181                        swizzle, state))
 182          return false;
 183
 184       return match_value(expr->srcs[1], instr, 0, num_components,
 185                          swizzle, state);
 186    } else {
 187       return false;
 188    }
 189 }
 190
 191 static nir_alu_src
 192 construct_value(const nir_search_value *value, nir_alu_type type,
 193                 unsigned num_components, struct match_state *state,
 194                 nir_instr *instr, void *mem_ctx)
 195 {
 196    switch (value->type) {
 197    case nir_search_value_expression: {
 198       const nir_search_expression *expr = nir_search_value_as_expression(value);
 199
 200       if (nir_op_infos[expr->opcode].output_size != 0)
 201          num_components = nir_op_infos[expr->opcode].output_size;
 202
 203       nir_alu_instr *alu = nir_alu_instr_create(mem_ctx, expr->opcode);
 204       nir_ssa_dest_init(&alu->instr, &alu->dest.dest, num_components, NULL);
 205       alu->dest.write_mask = (1 << num_components) - 1;
 206       alu->dest.saturate = false;
 207
 208       for (unsigned i = 0; i < nir_op_infos[expr->opcode].num_inputs; i++) {
 209          /* If the source is an explicitly sized source, then we need to reset
 210           * the number of components to match.
 211           */
 212          if (nir_op_infos[alu->op].input_sizes[i] != 0)
 213             num_components = nir_op_infos[alu->op].input_sizes[i];
 214
 215          alu->src[i] = construct_value(expr->srcs[i],
 216                                        nir_op_infos[alu->op].input_types[i],
 217                                        num_components,
 218                                        state, instr, mem_ctx);
 219       }
 220
 221       nir_instr_insert_before(instr, &alu->instr);
 222
 223       nir_alu_src val;
 224       val.src = nir_src_for_ssa(&alu->dest.dest.ssa);
 225       val.negate = false;
 226       val.abs = false,
 227       memcpy(val.swizzle, identity_swizzle, sizeof val.swizzle);
 228
 229       return val;
 230    }
 231
 232    case nir_search_value_variable: {
 233       const nir_search_variable *var = nir_search_value_as_variable(value);
 234       assert(state->variables_seen & (1 << var->variable));
 235
 236       nir_alu_src val;
 237       nir_alu_src_copy(&val, &state->variables[var->variable], mem_ctx);
 238
 239       return val;
 240    }
 241
 242    case nir_search_value_constant: {
 243       const nir_search_constant *c = nir_search_value_as_constant(value);
 244       nir_load_const_instr *load = nir_load_const_instr_create(mem_ctx, 1);
 245
 246       switch (type) {
 247       case nir_type_float:
 248          load->def.name = ralloc_asprintf(mem_ctx, "%f", c->data.f);
 249          load->value.f[0] = c->data.f;
 250          break;
 251       case nir_type_int:
 252          load->def.name = ralloc_asprintf(mem_ctx, "%d", c->data.i);
 253          load->value.i[0] = c->data.i;
 254          break;
 255       case nir_type_unsigned:
 256       case nir_type_bool:
 257          load->value.u[0] = c->data.u;
 258          break;
 259       default:
 260          unreachable("Invalid alu source type");
 261       }
 262
 263       nir_instr_insert_before(instr, &load->instr);
 264
 265       nir_alu_src val;
 266       val.src = nir_src_for_ssa(&load->def);
 267       val.negate = false;
 268       val.abs = false,
 269       memset(val.swizzle, 0, sizeof val.swizzle);
 270
 271       return val;
 272    }
 273
 274    default:
 275       unreachable("Invalid search value type");
 276    }
 277 }
 278
 279 nir_alu_instr *
 280 nir_replace_instr(nir_alu_instr *instr, const nir_search_expression *search,
 281                   const nir_search_value *replace, void *mem_ctx)
 282 {
 283    uint8_t swizzle[4] = { 0, 0, 0, 0 };
 284
 285    for (unsigned i = 0; i < instr->dest.dest.ssa.num_components; ++i)
 286       swizzle[i] = i;
 287
 288    assert(instr->dest.dest.is_ssa);
 289
 290    struct match_state state;
 291    state.variables_seen = 0;
 292
 293    if (!match_expression(search, instr, instr->dest.dest.ssa.num_components,
 294                          swizzle, &state))
 295       return NULL;
 296
 297    /* Inserting a mov may be unnecessary.  However, it's much easier to
 298     * simply let copy propagation clean this up than to try to go through
 299     * and rewrite swizzles ourselves.
 300     */
 301    nir_alu_instr *mov = nir_alu_instr_create(mem_ctx, nir_op_imov);
 302    mov->dest.write_mask = instr->dest.write_mask;
 303    nir_ssa_dest_init(&mov->instr, &mov->dest.dest,
 304                      instr->dest.dest.ssa.num_components, NULL);
 305
 306    mov->src[0] = construct_value(replace, nir_op_infos[instr->op].output_type,
 307                                  instr->dest.dest.ssa.num_components, &state,
 308                                  &instr->instr, mem_ctx);
 309    nir_instr_insert_before(&instr->instr, &mov->instr);
 310
 311    nir_ssa_def_rewrite_uses(&instr->dest.dest.ssa,
 312                             nir_src_for_ssa(&mov->dest.dest.ssa), mem_ctx);
 313
 314    /* We know this one has no more uses because we just rewrote them all,
 315     * so we can remove it.  The rest of the matched expression, however, we
 316     * don't know so much about.  We'll just let dead code clean them up.
 317     */
 318    nir_instr_remove(&instr->instr);
 319
 320    return mov;
 321 }