workbench/libs/mesa/src/glsl/lower_noise.cpp

   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
  21  * DEALINGS IN THE SOFTWARE.
  22  */
  23
  24 /**
  25  * \file lower_noise.cpp
  26  * IR lower pass to remove noise opcodes.
  27  *
  28  * \author Ian Romanick <ian.d.romanick@intel.com>
  29  */
  30
  31 #include "ir.h"
  32 #include "ir_rvalue_visitor.h"
  33
  34 class lower_noise_visitor : public ir_rvalue_visitor {
  35 public:
  36    lower_noise_visitor() : progress(false)
  37    {
  38       /* empty */
  39    }
  40
  41    void handle_rvalue(ir_rvalue **rvalue)
  42    {
  43       if (!*rvalue)
  44          return;
  45
  46       ir_expression *expr = (*rvalue)->as_expression();
  47       if (!expr)
  48          return;
  49
  50       /* In the future, ir_unop_noise may be replaced by a call to a function
  51        * that implements noise.  No hardware has a noise instruction.
  52        */
  53       if (expr->operation == ir_unop_noise) {
  54          *rvalue = ir_constant::zero(ralloc_parent(expr), expr->type);
  55          this->progress = true;
  56       }
  57    }
  58
  59    bool progress;
  60 };
  61
  62
  63 bool
  64 lower_noise(exec_list *instructions)
  65 {
  66    lower_noise_visitor v;
  67
  68    visit_list_elements(&v, instructions);
  69
  70    return v.progress;
  71 }