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->start_ip - 1;
  36
  37    for (fs_inst *inst = (fs_inst *)block->start;
  38         inst != block->end->next;
  39         inst = (fs_inst *) inst->next) {
  40       ip++;
  41
  42       if (inst->opcode != BRW_OPCODE_MOV ||
  43           inst->dst.file != GRF ||
  44           inst->src[0].file != GRF ||
  45           inst->src[0].abs ||
  46           inst->src[0].negate ||
  47           !inst->saturate)
  48          continue;
  49
  50       int src_var = v->live_intervals->var_from_reg(&inst->src[0]);
  51       int src_end_ip = v->live_intervals->end[src_var];
  52       if (src_end_ip > ip && !inst->dst.equals(inst->src[0]))
  53          continue;
  54
  55       int scan_ip = ip;
  56       bool interfered = false;
  57       for (fs_inst *scan_inst = (fs_inst *) inst->prev;
  58            scan_inst != block->start->prev;
  59            scan_inst = (fs_inst *) scan_inst->prev) {
  60          scan_ip--;
  61
  62          if (scan_inst->dst.file == GRF &&
  63              scan_inst->dst.reg == inst->src[0].reg &&
  64              scan_inst->dst.reg_offset == inst->src[0].reg_offset &&
  65              !scan_inst->is_partial_write()) {
  66             if (scan_inst->can_do_saturate()) {
  67                scan_inst->saturate = true;
  68                inst->saturate = false;
  69                progress = true;
  70             }
  71             break;
  72          }
  73          for (int i = 0; i < scan_inst->sources; i++) {
  74             if (scan_inst->src[i].file == GRF &&
  75                 scan_inst->src[i].reg == inst->src[0].reg &&
  76                 scan_inst->src[i].reg_offset == inst->src[0].reg_offset) {
  77                interfered = true;
  78                break;
  79             }
  80          }
  81
  82          if (interfered)
  83             break;
  84       }
  85    }
  86
  87    return progress;
  88 }
  89
  90 bool
  91 fs_visitor::opt_saturate_propagation()
  92 {
  93    bool progress = false;
  94
  95    calculate_live_intervals();
  96
  97    cfg_t cfg(&instructions);
  98
  99    for (int b = 0; b < cfg.num_blocks; b++) {
 100       progress = opt_saturate_propagation_local(this, cfg.blocks[b])
 101                  || progress;
 102    }
 103
 104    if (progress)
 105       invalidate_live_intervals();
 106
 107    return progress;
 108 }