src/glsl/ir_mod_to_fract.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 ir_mod_to_fract.cpp
  26  *
  27  * Breaks an ir_unop_mod expression down to (op1 * fract(op0 / op1))
  28  *
  29  * Many GPUs don't have a MOD instruction (945 and 965 included), and
  30  * if we have to break it down like this anyway, it gives an
  31  * opportunity to do things like constant fold the (1.0 / op1) easily.
  32  */
  33
  34 #include "ir.h"
  35
  36 class ir_mod_to_fract_visitor : public ir_hierarchical_visitor {
  37 public:
  38    ir_mod_to_fract_visitor()
  39    {
  40       this->made_progress = false;
  41    }
  42
  43    ir_visitor_status visit_leave(ir_expression *);
  44
  45    bool made_progress;
  46 };
  47
  48 bool
  49 do_mod_to_fract(exec_list *instructions)
  50 {
  51    ir_mod_to_fract_visitor v;
  52
  53    visit_list_elements(&v, instructions);
  54    return v.made_progress;
  55 }
  56
  57 ir_visitor_status
  58 ir_mod_to_fract_visitor::visit_leave(ir_expression *ir)
  59 {
  60    if (ir->operation != ir_binop_mod)
  61       return visit_continue;
  62
  63    ir_variable *temp = new(ir) ir_variable(ir->operands[1]->type, "mod_b",
  64                                            ir_var_temporary);
  65    this->base_ir->insert_before(temp);
  66
  67    ir_assignment *assign;
  68    ir_rvalue *expr;
  69
  70    assign = new(ir) ir_assignment(new(ir) ir_dereference_variable(temp),
  71                                   ir->operands[1], NULL);
  72    this->base_ir->insert_before(assign);
  73
  74    expr = new(ir) ir_expression(ir_binop_div,
  75                                 ir->operands[0]->type,
  76                                 ir->operands[0],
  77                                 new(ir) ir_dereference_variable(temp));
  78
  79    expr = new(ir) ir_expression(ir_unop_fract,
  80                                 ir->operands[0]->type,
  81                                 expr,
  82                                 NULL);
  83
  84    ir->operation = ir_binop_mul;
  85    ir->operands[0] = new(ir) ir_dereference_variable(temp);
  86    ir->operands[1] = expr;
  87    this->made_progress = true;
  88
  89    return visit_continue;
  90 }