src/mesa/drivers/dri/i965/brw_optimize.c

   1 /*
   2  * Copyright © 2010 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  * Authors:
  24  *    Eric Anholt <eric@anholt.net>
  25  *
  26  */
  27
  28 #include "main/macros.h"
  29 #include "shader/program.h"
  30 #include "shader/prog_print.h"
  31 #include "brw_context.h"
  32 #include "brw_defines.h"
  33 #include "brw_eu.h"
  34
  35 static GLboolean
  36 is_single_channel_dp4(struct brw_instruction *insn)
  37 {
  38    if (insn->header.opcode != BRW_OPCODE_DP4 ||
  39        insn->header.execution_size != BRW_EXECUTE_8 ||
  40        insn->header.access_mode != BRW_ALIGN_16 ||
  41        insn->bits1.da1.dest_reg_file != BRW_GENERAL_REGISTER_FILE)
  42       return GL_FALSE;
  43
  44    if (!is_power_of_two(insn->bits1.da16.dest_writemask))
  45       return GL_FALSE;
  46
  47    return GL_TRUE;
  48 }
  49
  50 /**
  51  * Sets the dependency control fields on DP4 instructions.
  52  *
  53  * The hardware only tracks dependencies on a register basis, so when
  54  * you do:
  55  *
  56  * DP4 dst.x src1 src2
  57  * DP4 dst.y src1 src3
  58  * DP4 dst.z src1 src4
  59  * DP4 dst.w src1 src5
  60  *
  61  * It will wait to do the DP4 dst.y until the dst.x is resolved, etc.
  62  * We can examine our instruction stream and set the dependency
  63  * control fields to tell the hardware when to do it.
  64  *
  65  * We may want to extend this to other instructions that are used to
  66  * fill in a channel at a time of the destination register.
  67  */
  68 static void
  69 brw_set_dp4_dependency_control(struct brw_compile *p)
  70 {
  71    int i;
  72
  73    for (i = 1; i < p->nr_insn; i++) {
  74       struct brw_instruction *insn = &p->store[i];
  75       struct brw_instruction *prev = &p->store[i - 1];
  76
  77       if (!is_single_channel_dp4(prev))
  78          continue;
  79
  80       if (!is_single_channel_dp4(insn)) {
  81          i++;
  82          continue;
  83       }
  84
  85       /* Only avoid hw dep control if the write masks are different
  86        * channels of one reg.
  87        */
  88       if (insn->bits1.da16.dest_writemask == prev->bits1.da16.dest_writemask)
  89          continue;
  90       if (insn->bits1.da16.dest_reg_nr != prev->bits1.da16.dest_reg_nr)
  91          continue;
  92
  93       /* Check if the second instruction depends on the previous one
  94        * for a src.
  95        */
  96       if (insn->bits1.da1.src0_reg_file == BRW_GENERAL_REGISTER_FILE &&
  97           (insn->bits2.da1.src0_address_mode != BRW_ADDRESS_DIRECT ||
  98            insn->bits2.da1.src0_reg_nr == insn->bits1.da16.dest_reg_nr))
  99           continue;
 100       if (insn->bits1.da1.src1_reg_file == BRW_GENERAL_REGISTER_FILE &&
 101           (insn->bits3.da1.src1_address_mode != BRW_ADDRESS_DIRECT ||
 102            insn->bits3.da1.src1_reg_nr == insn->bits1.da16.dest_reg_nr))
 103           continue;
 104
 105       prev->header.dependency_control |= BRW_DEPENDENCY_NOTCLEARED;
 106       insn->header.dependency_control |= BRW_DEPENDENCY_NOTCHECKED;
 107    }
 108 }
 109
 110 void
 111 brw_optimize(struct brw_compile *p)
 112 {
 113    brw_set_dp4_dependency_control(p);
 114 }