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      1 /*
      2  * Mesa 3-D graphics library
      3  *
      4  * Copyright (C) 2012-2013 LunarG, Inc.
      5  *
      6  * Permission is hereby granted, free of charge, to any person obtaining a
      7  * copy of this software and associated documentation files (the "Software"),
      8  * to deal in the Software without restriction, including without limitation
      9  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
     10  * and/or sell copies of the Software, and to permit persons to whom the
     11  * Software is furnished to do so, subject to the following conditions:
     12  *
     13  * The above copyright notice and this permission notice shall be included
     14  * in all copies or substantial portions of the Software.
     15  *
     16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
     17  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
     18  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
     19  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
     20  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
     21  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
     22  * DEALINGS IN THE SOFTWARE.
     23  *
     24  * Authors:
     25  *    Chia-I Wu <olv (at) lunarg.com>
     26  */
     27 
     28 #include "toy_compiler.h"
     29 #include "toy_tgsi.h"
     30 #include "toy_optimize.h"
     31 
     32 /**
     33  * This just eliminates instructions with null dst so far.
     34  */
     35 static void
     36 eliminate_dead_code(struct toy_compiler *tc)
     37 {
     38    struct toy_inst *inst;
     39 
     40    tc_head(tc);
     41    while ((inst = tc_next(tc)) != NULL) {
     42       switch (inst->opcode) {
     43       case GEN6_OPCODE_IF:
     44       case GEN6_OPCODE_ELSE:
     45       case GEN6_OPCODE_ENDIF:
     46       case GEN6_OPCODE_WHILE:
     47       case GEN6_OPCODE_BREAK:
     48       case GEN6_OPCODE_CONT:
     49       case GEN6_OPCODE_SEND:
     50       case GEN6_OPCODE_SENDC:
     51       case GEN6_OPCODE_NOP:
     52          /* never eliminated */
     53          break;
     54       default:
     55          if (tdst_is_null(inst->dst) || !inst->dst.writemask) {
     56             /* math is always GEN6_COND_NORMAL */
     57             if ((inst->opcode == GEN6_OPCODE_MATH ||
     58                  inst->cond_modifier == GEN6_COND_NONE) &&
     59                 !inst->acc_wr_ctrl)
     60                tc_discard_inst(tc, inst);
     61          }
     62          break;
     63       }
     64    }
     65 }
     66 
     67 void
     68 toy_compiler_optimize(struct toy_compiler *tc)
     69 {
     70    eliminate_dead_code(tc);
     71 }
     72