src/glsl/ir_explog_to_explog2.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_explog_to_explog2.cpp
  26  *
  27  * Many GPUs don't have a base e log or exponent instruction, but they
  28  * do have base 2 versions, so this pass converts exp and log to exp2
  29  * and log2 operations.
  30  */
  31
  32 #include <math.h>
  33 #include "ir.h"
  34 #include "glsl_types.h"
  35
  36 class ir_explog_to_explog2_visitor : public ir_hierarchical_visitor {
  37 public:
  38    ir_explog_to_explog2_visitor()
  39    {
  40       this->progress = false;
  41    }
  42
  43    ir_visitor_status visit_leave(ir_expression *);
  44
  45    bool progress;
  46 };
  47
  48 bool
  49 do_explog_to_explog2(exec_list *instructions)
  50 {
  51    ir_explog_to_explog2_visitor v;
  52
  53    visit_list_elements(&v, instructions);
  54    return v.progress;
  55 }
  56
  57 ir_visitor_status
  58 ir_explog_to_explog2_visitor::visit_leave(ir_expression *ir)
  59 {
  60    if (ir->operation == ir_unop_exp) {
  61       void *mem_ctx = talloc_parent(ir);
  62       ir_constant *log2_e = new(mem_ctx) ir_constant(log2f(M_E));
  63
  64       ir->operation = ir_unop_exp2;
  65       ir->operands[0] = new(mem_ctx) ir_expression(ir_binop_mul,
  66                                                    ir->operands[0]->type,
  67                                                    ir->operands[0],
  68                                                    log2_e);
  69       this->progress = true;
  70    }
  71
  72    if (ir->operation == ir_unop_log) {
  73       void *mem_ctx = talloc_parent(ir);
  74
  75       ir->operation = ir_binop_mul;
  76       ir->operands[0] = new(mem_ctx) ir_expression(ir_unop_log2,
  77                                                    ir->operands[0]->type,
  78                                                    ir->operands[0],
  79                                                    NULL);
  80       ir->operands[1] = new(mem_ctx) ir_constant(1.0f / log2f(M_E));
  81       this->progress = true;
  82    }
  83
  84    return visit_continue;
  85 }