src/gallium/drivers/vc4/vc4_opt_constant_folding.c

   1 /*
   2  * Copyright © 2015 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_constant_folding.c
  26  *
  27  * Simple constant folding pass to clean up operations on only constants,
  28  * which we might have generated within vc4_program.c.
  29  */
  30
  31 #include "vc4_qir.h"
  32 #include "util/u_math.h"
  33
  34 static bool debug;
  35
  36 static void
  37 dump_from(struct vc4_compile *c, struct qinst *inst)
  38 {
  39         if (!debug)
  40                 return;
  41
  42         fprintf(stderr, "optimizing: ");
  43         qir_dump_inst(c, inst);
  44         fprintf(stderr, "\n");
  45 }
  46
  47 static void
  48 dump_to(struct vc4_compile *c, struct qinst *inst)
  49 {
  50         if (!debug)
  51                 return;
  52
  53         fprintf(stderr, "to: ");
  54         qir_dump_inst(c, inst);
  55         fprintf(stderr, "\n");
  56 }
  57
  58 static bool
  59 constant_fold(struct vc4_compile *c, struct qinst *inst)
  60 {
  61         int nsrc = qir_get_nsrc(inst);
  62         uint32_t ui[nsrc];
  63
  64         for (int i = 0; i < nsrc; i++) {
  65                 struct qreg reg = inst->src[i];
  66                 if (reg.file == QFILE_UNIF &&
  67                     c->uniform_contents[reg.index] == QUNIFORM_CONSTANT) {
  68                         ui[i] = c->uniform_data[reg.index];
  69                 } else if (reg.file == QFILE_SMALL_IMM) {
  70                         ui[i] = reg.index;
  71                 } else {
  72                         return false;
  73                 }
  74         }
  75
  76         uint32_t result = 0;
  77         switch (inst->op) {
  78         case QOP_SHR:
  79                 result = ui[0] >> ui[1];
  80                 break;
  81
  82         default:
  83                 return false;
  84         }
  85
  86         dump_from(c, inst);
  87
  88         inst->src[0] = qir_uniform_ui(c, result);
  89         for (int i = 1; i < nsrc; i++)
  90                 inst->src[i] = c->undef;
  91         inst->op = QOP_MOV;
  92
  93         dump_to(c, inst);
  94         return true;
  95 }
  96
  97 bool
  98 qir_opt_constant_folding(struct vc4_compile *c)
  99 {
 100         bool progress = false;
 101
 102         qir_for_each_inst_inorder(inst, c) {
 103                 if (constant_fold(c, inst))
 104                         progress = true;
 105         }
 106
 107         return progress;
 108 }