src/gallium/drivers/vc4/vc4_opt_algebraic.c

   1 /*
   2  * Copyright © 2014 Broadcom
   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
  24 /**
  25  * @file vc4_opt_algebraic.c
  26  *
  27  * This is the optimization pass for miscellaneous changes to instructions
  28  * where we can simplify the operation by some knowledge about the specific
  29  * operations.
  30  *
  31  * Mostly this will be a matter of turning things into MOVs so that they can
  32  * later be copy-propagated out.
  33  */
  34
  35 #include "vc4_qir.h"
  36 #include "util/u_math.h"
  37
  38 static bool debug;
  39
  40 static void
  41 dump_from(struct vc4_compile *c, struct qinst *inst)
  42 {
  43         if (!debug)
  44                 return;
  45
  46         fprintf(stderr, "optimizing: ");
  47         qir_dump_inst(c, inst);
  48         fprintf(stderr, "\n");
  49 }
  50
  51 static void
  52 dump_to(struct vc4_compile *c, struct qinst *inst)
  53 {
  54         if (!debug)
  55                 return;
  56
  57         fprintf(stderr, "to: ");
  58         qir_dump_inst(c, inst);
  59         fprintf(stderr, "\n");
  60 }
  61
  62 static bool
  63 is_constant_value(struct vc4_compile *c, struct qreg reg,
  64                   uint32_t val)
  65 {
  66         if (reg.file == QFILE_UNIF &&
  67             c->uniform_contents[reg.index] == QUNIFORM_CONSTANT &&
  68             c->uniform_data[reg.index] == val) {
  69                 return true;
  70         }
  71
  72         if (reg.file == QFILE_SMALL_IMM && reg.index == val)
  73                 return true;
  74
  75         return false;
  76 }
  77
  78 static bool
  79 is_zero(struct vc4_compile *c, struct qreg reg)
  80 {
  81         reg = qir_follow_movs(c, reg);
  82         return is_constant_value(c, reg, 0);
  83 }
  84
  85 static bool
  86 is_1f(struct vc4_compile *c, struct qreg reg)
  87 {
  88         reg = qir_follow_movs(c, reg);
  89         return is_constant_value(c, reg, fui(1.0));
  90 }
  91
  92 static void
  93 replace_with_mov(struct vc4_compile *c, struct qinst *inst, struct qreg arg)
  94 {
  95         dump_from(c, inst);
  96         inst->op = QOP_MOV;
  97         inst->src[0] = arg;
  98         inst->src[1] = c->undef;
  99         dump_to(c, inst);
 100 }
 101
 102 static bool
 103 replace_x_0_with_x(struct vc4_compile *c,
 104                  struct qinst *inst,
 105                  int arg)
 106 {
 107         if (!is_zero(c, inst->src[arg]))
 108                 return false;
 109         replace_with_mov(c, inst, inst->src[1 - arg]);
 110         return true;
 111 }
 112
 113 static bool
 114 replace_x_0_with_0(struct vc4_compile *c,
 115                   struct qinst *inst,
 116                   int arg)
 117 {
 118         if (!is_zero(c, inst->src[arg]))
 119                 return false;
 120         replace_with_mov(c, inst, inst->src[arg]);
 121         return true;
 122 }
 123
 124 static bool
 125 fmul_replace_one(struct vc4_compile *c,
 126                  struct qinst *inst,
 127                  int arg)
 128 {
 129         if (!is_1f(c, inst->src[arg]))
 130                 return false;
 131         replace_with_mov(c, inst, inst->src[1 - arg]);
 132         return true;
 133 }
 134
 135 bool
 136 qir_opt_algebraic(struct vc4_compile *c)
 137 {
 138         bool progress = false;
 139
 140         list_for_each_entry(struct qinst, inst, &c->instructions, link) {
 141                 switch (inst->op) {
 142                 case QOP_SEL_X_Y_ZS:
 143                 case QOP_SEL_X_Y_ZC:
 144                 case QOP_SEL_X_Y_NS:
 145                 case QOP_SEL_X_Y_NC:
 146                         if (is_zero(c, inst->src[1])) {
 147                                 /* Replace references to a 0 uniform value
 148                                  * with the SEL_X_0 equivalent.
 149                                  */
 150                                 dump_from(c, inst);
 151                                 inst->op -= (QOP_SEL_X_Y_ZS - QOP_SEL_X_0_ZS);
 152                                 inst->src[1] = c->undef;
 153                                 progress = true;
 154                                 dump_to(c, inst);
 155                                 break;
 156                         }
 157
 158                         if (is_zero(c, inst->src[0])) {
 159                                 /* Replace references to a 0 uniform value
 160                                  * with the SEL_X_0 equivalent, flipping the
 161                                  * condition being evaluated since the operand
 162                                  * order is flipped.
 163                                  */
 164                                 dump_from(c, inst);
 165                                 inst->op -= QOP_SEL_X_Y_ZS;
 166                                 inst->op ^= 1;
 167                                 inst->op += QOP_SEL_X_0_ZS;
 168                                 inst->src[0] = inst->src[1];
 169                                 inst->src[1] = c->undef;
 170                                 progress = true;
 171                                 dump_to(c, inst);
 172                                 break;
 173                         }
 174
 175                         break;
 176
 177                 case QOP_FSUB:
 178                 case QOP_SUB:
 179                         if (is_zero(c, inst->src[1])) {
 180                                 replace_with_mov(c, inst, inst->src[0]);
 181                         }
 182                         break;
 183
 184                 case QOP_ADD:
 185                         if (replace_x_0_with_x(c, inst, 0) ||
 186                             replace_x_0_with_x(c, inst, 1)) {
 187                                 progress = true;
 188                                 break;
 189                         }
 190                         break;
 191
 192                 case QOP_FADD:
 193                         if (replace_x_0_with_x(c, inst, 0) ||
 194                             replace_x_0_with_x(c, inst, 1)) {
 195                                 progress = true;
 196                                 break;
 197                         }
 198
 199                         /* FADD(a, FSUB(0, b)) -> FSUB(a, b) */
 200                         if (inst->src[1].file == QFILE_TEMP &&
 201                             c->defs[inst->src[1].index] &&
 202                             c->defs[inst->src[1].index]->op == QOP_FSUB) {
 203                                 struct qinst *fsub = c->defs[inst->src[1].index];
 204                                 if (is_zero(c, fsub->src[0])) {
 205                                         dump_from(c, inst);
 206                                         inst->op = QOP_FSUB;
 207                                         inst->src[1] = fsub->src[1];
 208                                         progress = true;
 209                                         dump_to(c, inst);
 210                                         break;
 211                                 }
 212                         }
 213
 214                         /* FADD(FSUB(0, b), a) -> FSUB(a, b) */
 215                         if (inst->src[0].file == QFILE_TEMP &&
 216                             c->defs[inst->src[0].index] &&
 217                             c->defs[inst->src[0].index]->op == QOP_FSUB) {
 218                                 struct qinst *fsub = c->defs[inst->src[0].index];
 219                                 if (is_zero(c, fsub->src[0])) {
 220                                         dump_from(c, inst);
 221                                         inst->op = QOP_FSUB;
 222                                         inst->src[0] = inst->src[1];
 223                                         inst->src[1] = fsub->src[1];
 224                                         dump_to(c, inst);
 225                                         progress = true;
 226                                         break;
 227                                 }
 228                         }
 229                         break;
 230
 231                 case QOP_FMUL:
 232                         if (!inst->dst.pack &&
 233                             (replace_x_0_with_0(c, inst, 0) ||
 234                              replace_x_0_with_0(c, inst, 1) ||
 235                              fmul_replace_one(c, inst, 0) ||
 236                              fmul_replace_one(c, inst, 1))) {
 237                                 progress = true;
 238                                 break;
 239                         }
 240                         break;
 241
 242                 case QOP_MUL24:
 243                         if (!inst->dst.pack &&
 244                             (replace_x_0_with_0(c, inst, 0) ||
 245                              replace_x_0_with_0(c, inst, 1))) {
 246                                 progress = true;
 247                                 break;
 248                         }
 249                         break;
 250
 251                 case QOP_AND:
 252                         if (replace_x_0_with_0(c, inst, 0) ||
 253                             replace_x_0_with_0(c, inst, 1)) {
 254                                 progress = true;
 255                                 break;
 256                         }
 257
 258                         if (is_constant_value(c, inst->src[0], ~0)) {
 259                                 replace_with_mov(c, inst, inst->src[1]);
 260                                 progress = true;
 261                                 break;
 262                         }
 263                         if (is_constant_value(c, inst->src[1], ~0)) {
 264                                 replace_with_mov(c, inst, inst->src[0]);
 265                                 progress = true;
 266                                 break;
 267                         }
 268                         break;
 269
 270                 case QOP_OR:
 271                         if (replace_x_0_with_x(c, inst, 0) ||
 272                             replace_x_0_with_x(c, inst, 1)) {
 273                                 progress = true;
 274                                 break;
 275                         }
 276                         break;
 277
 278                 default:
 279                         break;
 280                 }
 281         }
 282
 283         return progress;
 284 }