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->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       if (src_end_ip > ip && !inst->dst.equals(inst->src[0]))
  51          continue;
  52
  53       int scan_ip = ip;
  54       bool interfered = false;
  55       for (fs_inst *scan_inst = (fs_inst *) inst->prev;
  56            scan_inst != block->start->prev;
  57            scan_inst = (fs_inst *) scan_inst->prev) {
  58          scan_ip--;
  59
  60          if (scan_inst->dst.file == GRF &&
  61              scan_inst->dst.reg == inst->src[0].reg &&
  62              scan_inst->dst.reg_offset == inst->src[0].reg_offset &&
  63              !scan_inst->is_partial_write()) {
  64             if (scan_inst->can_do_saturate()) {
  65                scan_inst->saturate = true;
  66                inst->saturate = false;
  67                progress = true;
  68             }
  69             break;
  70          }
  71          for (int i = 0; i < 3; i++) {
  72             if (scan_inst->src[i].file == GRF &&
  73                 scan_inst->src[i].reg == inst->src[0].reg &&
  74                 scan_inst->src[i].reg_offset == inst->src[0].reg_offset) {
  75                interfered = true;
  76                break;
  77             }
  78          }
  79
  80          if (interfered)
  81             break;
  82       }
  83    }
  84
  85    return progress;
  86 }
  87
  88 bool
  89 fs_visitor::opt_saturate_propagation()
  90 {
  91    bool progress = false;
  92
  93    calculate_live_intervals();
  94
  95    cfg_t cfg(&instructions);
  96
  97    for (int b = 0; b < cfg.num_blocks; b++) {
  98       progress = opt_saturate_propagation_local(this, cfg.blocks[b])
  99                  || progress;
 100    }
 101
 102    if (progress)
 103       invalidate_live_intervals();
 104
 105    return progress;
 106 }