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             !reg.pack &&
  68             c->uniform_contents[reg.index] == QUNIFORM_CONSTANT &&
  69             c->uniform_data[reg.index] == val) {
  70                 return true;
  71         }
  72
  73         if (reg.file == QFILE_SMALL_IMM && reg.index == val)
  74                 return true;
  75
  76         return false;
  77 }
  78
  79 static bool
  80 is_zero(struct vc4_compile *c, struct qreg reg)
  81 {
  82         reg = qir_follow_movs(c, reg);
  83         return is_constant_value(c, reg, 0);
  84 }
  85
  86 static bool
  87 is_1f(struct vc4_compile *c, struct qreg reg)
  88 {
  89         reg = qir_follow_movs(c, reg);
  90         return is_constant_value(c, reg, fui(1.0));
  91 }
  92
  93 static void
  94 replace_with_mov(struct vc4_compile *c, struct qinst *inst, struct qreg arg)
  95 {
  96         dump_from(c, inst);
  97         inst->op = QOP_MOV;
  98         inst->src[0] = arg;
  99         inst->src[1] = c->undef;
 100         dump_to(c, inst);
 101 }
 102
 103 static bool
 104 replace_x_0_with_x(struct vc4_compile *c,
 105                  struct qinst *inst,
 106                  int arg)
 107 {
 108         if (!is_zero(c, inst->src[arg]))
 109                 return false;
 110         replace_with_mov(c, inst, inst->src[1 - arg]);
 111         return true;
 112 }
 113
 114 static bool
 115 replace_x_0_with_0(struct vc4_compile *c,
 116                   struct qinst *inst,
 117                   int arg)
 118 {
 119         if (!is_zero(c, inst->src[arg]))
 120                 return false;
 121         replace_with_mov(c, inst, inst->src[arg]);
 122         return true;
 123 }
 124
 125 static bool
 126 fmul_replace_one(struct vc4_compile *c,
 127                  struct qinst *inst,
 128                  int arg)
 129 {
 130         if (!is_1f(c, inst->src[arg]))
 131                 return false;
 132         replace_with_mov(c, inst, inst->src[1 - arg]);
 133         return true;
 134 }
 135
 136 bool
 137 qir_opt_algebraic(struct vc4_compile *c)
 138 {
 139         bool progress = false;
 140
 141         list_for_each_entry(struct qinst, inst, &c->instructions, link) {
 142                 switch (inst->op) {
 143                 case QOP_SEL_X_Y_ZS:
 144                 case QOP_SEL_X_Y_ZC:
 145                 case QOP_SEL_X_Y_NS:
 146                 case QOP_SEL_X_Y_NC:
 147                 case QOP_SEL_X_Y_CS:
 148                 case QOP_SEL_X_Y_CC:
 149                         if (is_zero(c, inst->src[1])) {
 150                                 /* Replace references to a 0 uniform value
 151                                  * with the SEL_X_0 equivalent.
 152                                  */
 153                                 dump_from(c, inst);
 154                                 inst->op -= (QOP_SEL_X_Y_ZS - QOP_SEL_X_0_ZS);
 155                                 inst->src[1] = c->undef;
 156                                 progress = true;
 157                                 dump_to(c, inst);
 158                                 break;
 159                         }
 160
 161                         if (is_zero(c, inst->src[0])) {
 162                                 /* Replace references to a 0 uniform value
 163                                  * with the SEL_X_0 equivalent, flipping the
 164                                  * condition being evaluated since the operand
 165                                  * order is flipped.
 166                                  */
 167                                 dump_from(c, inst);
 168                                 inst->op -= QOP_SEL_X_Y_ZS;
 169                                 inst->op ^= 1;
 170                                 inst->op += QOP_SEL_X_0_ZS;
 171                                 inst->src[0] = inst->src[1];
 172                                 inst->src[1] = c->undef;
 173                                 progress = true;
 174                                 dump_to(c, inst);
 175                                 break;
 176                         }
 177
 178                         break;
 179
 180                 case QOP_FSUB:
 181                 case QOP_SUB:
 182                         if (is_zero(c, inst->src[1])) {
 183                                 replace_with_mov(c, inst, inst->src[0]);
 184                                 progress = true;
 185                         }
 186                         break;
 187
 188                 case QOP_ADD:
 189                         if (replace_x_0_with_x(c, inst, 0) ||
 190                             replace_x_0_with_x(c, inst, 1)) {
 191                                 progress = true;
 192                                 break;
 193                         }
 194                         break;
 195
 196                 case QOP_FADD:
 197                         if (replace_x_0_with_x(c, inst, 0) ||
 198                             replace_x_0_with_x(c, inst, 1)) {
 199                                 progress = true;
 200                                 break;
 201                         }
 202
 203                         /* FADD(a, FSUB(0, b)) -> FSUB(a, b) */
 204                         if (inst->src[1].file == QFILE_TEMP &&
 205                             c->defs[inst->src[1].index] &&
 206                             c->defs[inst->src[1].index]->op == QOP_FSUB) {
 207                                 struct qinst *fsub = c->defs[inst->src[1].index];
 208                                 if (is_zero(c, fsub->src[0])) {
 209                                         dump_from(c, inst);
 210                                         inst->op = QOP_FSUB;
 211                                         inst->src[1] = fsub->src[1];
 212                                         progress = true;
 213                                         dump_to(c, inst);
 214                                         break;
 215                                 }
 216                         }
 217
 218                         /* FADD(FSUB(0, b), a) -> FSUB(a, b) */
 219                         if (inst->src[0].file == QFILE_TEMP &&
 220                             c->defs[inst->src[0].index] &&
 221                             c->defs[inst->src[0].index]->op == QOP_FSUB) {
 222                                 struct qinst *fsub = c->defs[inst->src[0].index];
 223                                 if (is_zero(c, fsub->src[0])) {
 224                                         dump_from(c, inst);
 225                                         inst->op = QOP_FSUB;
 226                                         inst->src[0] = inst->src[1];
 227                                         inst->src[1] = fsub->src[1];
 228                                         dump_to(c, inst);
 229                                         progress = true;
 230                                         break;
 231                                 }
 232                         }
 233                         break;
 234
 235                 case QOP_FMUL:
 236                         if (!inst->dst.pack &&
 237                             (replace_x_0_with_0(c, inst, 0) ||
 238                              replace_x_0_with_0(c, inst, 1) ||
 239                              fmul_replace_one(c, inst, 0) ||
 240                              fmul_replace_one(c, inst, 1))) {
 241                                 progress = true;
 242                                 break;
 243                         }
 244                         break;
 245
 246                 case QOP_MUL24:
 247                         if (!inst->dst.pack &&
 248                             (replace_x_0_with_0(c, inst, 0) ||
 249                              replace_x_0_with_0(c, inst, 1))) {
 250                                 progress = true;
 251                                 break;
 252                         }
 253                         break;
 254
 255                 case QOP_AND:
 256                         if (replace_x_0_with_0(c, inst, 0) ||
 257                             replace_x_0_with_0(c, inst, 1)) {
 258                                 progress = true;
 259                                 break;
 260                         }
 261
 262                         if (is_constant_value(c, inst->src[0], ~0)) {
 263                                 replace_with_mov(c, inst, inst->src[1]);
 264                                 progress = true;
 265                                 break;
 266                         }
 267                         if (is_constant_value(c, inst->src[1], ~0)) {
 268                                 replace_with_mov(c, inst, inst->src[0]);
 269                                 progress = true;
 270                                 break;
 271                         }
 272                         break;
 273
 274                 case QOP_OR:
 275                         if (replace_x_0_with_x(c, inst, 0) ||
 276                             replace_x_0_with_x(c, inst, 1)) {
 277                                 progress = true;
 278                                 break;
 279                         }
 280                         break;
 281
 282                 case QOP_RCP:
 283                         if (is_1f(c, inst->src[0])) {
 284                                 replace_with_mov(c, inst, inst->src[0]);
 285                                 progress = true;
 286                                 break;
 287                         }
 288                         break;
 289
 290                 default:
 291                         break;
 292                 }
 293         }
 294
 295         return progress;
 296 }