src/mesa/drivers/dri/i965/brw_fs_saturate_propagation.cpp

   1 /*
   2  * Copyright © 2013 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
  24 #include "brw_fs.h"
  25 #include "brw_fs_live_variables.h"
  26 #include "brw_cfg.h"
  27
  28 /** @file brw_fs_saturate_propagation.cpp
  29  */
  30
  31 static bool
  32 opt_saturate_propagation_local(fs_visitor *v, bblock_t *block)
  33 {
  34    bool progress = false;
  35    int ip = block->end_ip + 1;
  36
  37    foreach_inst_in_block_reverse(fs_inst, inst, block) {
  38       ip--;
  39
  40       if (inst->opcode != BRW_OPCODE_MOV ||
  41           inst->dst.file != GRF ||
  42           inst->src[0].file != GRF ||
  43           inst->src[0].abs ||
  44           inst->src[0].negate ||
  45           !inst->saturate)
  46          continue;
  47
  48       int src_var = v->live_intervals->var_from_reg(&inst->src[0]);
  49       int src_end_ip = v->live_intervals->end[src_var];
  50
  51       bool interfered = false;
  52       foreach_inst_in_block_reverse_starting_from(fs_inst, scan_inst, inst, block) {
  53          if (scan_inst->dst.file == GRF &&
  54              scan_inst->dst.reg == inst->src[0].reg &&
  55              scan_inst->dst.reg_offset == inst->src[0].reg_offset &&
  56              !scan_inst->is_partial_write()) {
  57             if (scan_inst->saturate) {
  58                inst->saturate = false;
  59                progress = true;
  60             } else if (src_end_ip <= ip || inst->dst.equals(inst->src[0])) {
  61                if (scan_inst->can_do_saturate()) {
  62                   scan_inst->saturate = true;
  63                   inst->saturate = false;
  64                   progress = true;
  65                }
  66             }
  67             break;
  68          }
  69          for (int i = 0; i < scan_inst->sources; i++) {
  70             if ((scan_inst->opcode != BRW_OPCODE_MOV || !scan_inst->saturate) &&
  71                 scan_inst->src[i].file == GRF &&
  72                 scan_inst->src[i].reg == inst->src[0].reg &&
  73                 scan_inst->src[i].reg_offset == inst->src[0].reg_offset) {
  74                interfered = true;
  75                break;
  76             }
  77          }
  78
  79          if (interfered)
  80             break;
  81       }
  82    }
  83
  84    return progress;
  85 }
  86
  87 bool
  88 fs_visitor::opt_saturate_propagation()
  89 {
  90    bool progress = false;
  91
  92    calculate_live_intervals();
  93
  94    foreach_block (block, cfg) {
  95       progress = opt_saturate_propagation_local(this, block) || progress;
  96    }
  97
  98    /* Live intervals are still valid. */
  99
 100    return progress;
 101 }