src/gallium/drivers/vc4/vc4_opt_small_immediates.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_small_immediates.c
  26  *
  27  * Turns references to small constant uniform values into small immediates
  28  * fields.
  29  */
  30
  31 #include "vc4_qir.h"
  32 #include "vc4_qpu.h"
  33
  34 static bool debug;
  35
  36 bool
  37 qir_opt_small_immediates(struct vc4_compile *c)
  38 {
  39         bool progress = false;
  40
  41         qir_for_each_inst_inorder(inst, c) {
  42                 /* The small immediate value sits in the raddr B field, so we
  43                  * can't have 2 small immediates in one instruction (unless
  44                  * they're the same value, but that should be optimized away
  45                  * elsewhere).
  46                  */
  47                 bool uses_small_imm = false;
  48                 for (int i = 0; i < qir_get_nsrc(inst); i++) {
  49                         if (inst->src[i].file == QFILE_SMALL_IMM)
  50                                 uses_small_imm = true;
  51                 }
  52                 if (uses_small_imm)
  53                         continue;
  54
  55                 /* Don't propagate small immediates into the top-end bounds
  56                  * checking for indirect UBO loads.  The kernel doesn't parse
  57                  * small immediates and rejects the shader in this case.  UBO
  58                  * loads are much more expensive than the uniform load, and
  59                  * indirect UBO regions are usually much larger than a small
  60                  * immediate, so it's not worth updating the kernel to allow
  61                  * optimizing it.
  62                  */
  63                 if (inst->op == QOP_MIN_NOIMM)
  64                         continue;
  65
  66                 for (int i = 0; i < qir_get_nsrc(inst); i++) {
  67                         struct qreg src = qir_follow_movs(c, inst->src[i]);
  68
  69                         if (src.file != QFILE_UNIF ||
  70                             src.pack ||
  71                             c->uniform_contents[src.index] !=
  72                             QUNIFORM_CONSTANT) {
  73                                 continue;
  74                         }
  75
  76                         if (qir_is_tex(inst) &&
  77                             i == qir_get_tex_uniform_src(inst)) {
  78                                 /* No turning the implicit uniform read into
  79                                  * an immediate.
  80                                  */
  81                                 continue;
  82                         }
  83
  84                         uint32_t imm = c->uniform_data[src.index];
  85                         uint32_t small_imm = qpu_encode_small_immediate(imm);
  86                         if (small_imm == ~0)
  87                                 continue;
  88
  89                         if (debug) {
  90                                 fprintf(stderr, "opt_small_immediate() from: ");
  91                                 qir_dump_inst(c, inst);
  92                                 fprintf(stderr, "\n");
  93                         }
  94                         inst->src[i].file = QFILE_SMALL_IMM;
  95                         inst->src[i].index = imm;
  96                         if (debug) {
  97                                 fprintf(stderr, "to: ");
  98                                 qir_dump_inst(c, inst);
  99                                 fprintf(stderr, "\n");
 100                         }
 101                         progress = true;
 102                         break;
 103                 }
 104         }
 105
 106         return progress;
 107 }