src/compiler/glsl/opt_add_neg_to_sub.h

   1 /*
   2  * Copyright © 2016 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
  21  * DEALINGS IN THE SOFTWARE.
  22  */
  23
  24 #ifndef OPT_ADD_NEG_TO_SUB_H
  25 #define OPT_ADD_NEG_TO_SUB_H
  26
  27 #include "ir.h"
  28 #include "ir_hierarchical_visitor.h"
  29
  30 class add_neg_to_sub_visitor : public ir_hierarchical_visitor {
  31 public:
  32    add_neg_to_sub_visitor()
  33    {
  34       /* empty */
  35    }
  36
  37    ir_visitor_status visit_leave(ir_expression *ir)
  38    {
  39       if (ir->operation != ir_binop_add)
  40          return visit_continue;
  41
  42       for (unsigned i = 0; i < 2; i++) {
  43          ir_expression *const op = ir->operands[i]->as_expression();
  44
  45          if (op != NULL && op->operation == ir_unop_neg) {
  46             ir->operation = ir_binop_sub;
  47
  48             /* This ensures that -a + b becomes b - a. */
  49             if (i == 0)
  50                ir->operands[0] = ir->operands[1];
  51
  52             ir->operands[1] = op->operands[0];
  53             break;
  54          }
  55       }
  56
  57       return visit_continue;
  58    }
  59 };
  60
  61 #endif /* OPT_ADD_NEG_TO_SUB_H */