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  * Implements a pass that propagates the SAT modifier from a MOV.SAT into the
  31  * instruction that produced the source of the MOV.SAT, thereby allowing the
  32  * MOV's src and dst to be coalesced and the MOV removed.
  33  *
  34  * For instance,
  35  *
  36  *    ADD     tmp, src0, src1
  37  *    MOV.SAT dst, tmp
  38  *
  39  * would be transformed into
  40  *
  41  *    ADD.SAT tmp, src0, src1
  42  *    MOV     dst, tmp
  43  */
  44
  45 static bool
  46 opt_saturate_propagation_local(fs_visitor *v, bblock_t *block)
  47 {
  48    bool progress = false;
  49    int ip = block->end_ip + 1;
  50
  51    foreach_inst_in_block_reverse(fs_inst, inst, block) {
  52       ip--;
  53
  54       if (inst->opcode != BRW_OPCODE_MOV ||
  55           !inst->saturate ||
  56           inst->dst.file != VGRF ||
  57           inst->dst.type != inst->src[0].type ||
  58           inst->src[0].file != VGRF ||
  59           inst->src[0].abs)
  60          continue;
  61
  62       int src_var = v->live_intervals->var_from_reg(inst->src[0]);
  63       int src_end_ip = v->live_intervals->end[src_var];
  64
  65       bool interfered = false;
  66       foreach_inst_in_block_reverse_starting_from(fs_inst, scan_inst, inst) {
  67          if (regions_overlap(scan_inst->dst, scan_inst->size_written,
  68                              inst->src[0], inst->size_read(0))) {
  69             if (scan_inst->is_partial_write() ||
  70                 (scan_inst->dst.type != inst->dst.type &&
  71                  !scan_inst->can_change_types()))
  72                break;
  73
  74             if (scan_inst->saturate) {
  75                inst->saturate = false;
  76                progress = true;
  77             } else if (src_end_ip == ip || inst->dst.equals(inst->src[0])) {
  78                if (scan_inst->can_do_saturate()) {
  79                   if (scan_inst->dst.type != inst->dst.type) {
  80                      scan_inst->dst.type = inst->dst.type;
  81                      for (int i = 0; i < scan_inst->sources; i++) {
  82                         scan_inst->src[i].type = inst->dst.type;
  83                      }
  84                   }
  85
  86                   if (inst->src[0].negate) {
  87                      if (scan_inst->opcode == BRW_OPCODE_MUL) {
  88                         scan_inst->src[0].negate = !scan_inst->src[0].negate;
  89                         inst->src[0].negate = false;
  90                      } else if (scan_inst->opcode == BRW_OPCODE_MAD) {
  91                         scan_inst->src[0].negate = !scan_inst->src[0].negate;
  92                         scan_inst->src[1].negate = !scan_inst->src[1].negate;
  93                         inst->src[0].negate = false;
  94                      } else if (scan_inst->opcode == BRW_OPCODE_ADD) {
  95                         if (scan_inst->src[1].file == IMM) {
  96                            if (!brw_negate_immediate(scan_inst->src[1].type,
  97                                                      &scan_inst->src[1].as_brw_reg())) {
  98                               break;
  99                            }
 100                         } else {
 101                            scan_inst->src[1].negate = !scan_inst->src[1].negate;
 102                         }
 103                         scan_inst->src[0].negate = !scan_inst->src[0].negate;
 104                         inst->src[0].negate = false;
 105                      } else {
 106                         break;
 107                      }
 108                   }
 109
 110                   scan_inst->saturate = true;
 111                   inst->saturate = false;
 112                   progress = true;
 113                }
 114             }
 115             break;
 116          }
 117          for (int i = 0; i < scan_inst->sources; i++) {
 118             if (scan_inst->src[i].file == VGRF &&
 119                 scan_inst->src[i].nr == inst->src[0].nr &&
 120                 scan_inst->src[i].offset / REG_SIZE ==
 121                  inst->src[0].offset / REG_SIZE) {
 122                if (scan_inst->opcode != BRW_OPCODE_MOV ||
 123                    !scan_inst->saturate ||
 124                    scan_inst->src[0].abs ||
 125                    scan_inst->src[0].negate ||
 126                    scan_inst->src[0].abs != inst->src[0].abs ||
 127                    scan_inst->src[0].negate != inst->src[0].negate) {
 128                   interfered = true;
 129                   break;
 130                }
 131             }
 132          }
 133
 134          if (interfered)
 135             break;
 136       }
 137    }
 138
 139    return progress;
 140 }
 141
 142 bool
 143 fs_visitor::opt_saturate_propagation()
 144 {
 145    bool progress = false;
 146
 147    calculate_live_intervals();
 148
 149    foreach_block (block, cfg) {
 150       progress = opt_saturate_propagation_local(this, block) || progress;
 151    }
 152
 153    /* Live intervals are still valid. */
 154
 155    return progress;
 156 }