ir_expression_flattening.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_expression_flattening.cpp
  26  *
  27  * Takes the leaves of expression trees and makes them dereferences of
  28  * assignments of the leaves to temporaries, according to a predicate.
  29  *
  30  * This is used for automatic function inlining, where we want to take
  31  * an expression containing a call and move the call out to its own
  32  * assignment so that we can inline it at the appropriate place in the
  33  * instruction stream.
  34  */
  35
  36 #include "ir.h"
  37 #include "ir_visitor.h"
  38 #include "ir_expression_flattening.h"
  39 #include "glsl_types.h"
  40
  41 class ir_expression_flattening_visitor : public ir_hierarchical_visitor {
  42 public:
  43    ir_expression_flattening_visitor(ir_instruction *base_ir,
  44                                     bool (*predicate)(ir_instruction *ir))
  45    {
  46       this->base_ir = base_ir;
  47       this->predicate = predicate;
  48    }
  49
  50    virtual ~ir_expression_flattening_visitor()
  51    {
  52       /* empty */
  53    }
  54
  55    virtual ir_visitor_status visit_enter(ir_call *);
  56    virtual ir_visitor_status visit_enter(ir_return *);
  57    virtual ir_visitor_status visit_enter(ir_function_signature *);
  58    virtual ir_visitor_status visit_enter(ir_if *);
  59    virtual ir_visitor_status visit_enter(ir_loop *);
  60    virtual ir_visitor_status visit_leave(ir_expression *);
  61    virtual ir_visitor_status visit_leave(ir_swizzle *);
  62
  63    bool (*predicate)(ir_instruction *ir);
  64    ir_instruction *base_ir;
  65 };
  66
  67 void
  68 do_expression_flattening(exec_list *instructions,
  69                          bool (*predicate)(ir_instruction *ir))
  70 {
  71    foreach_iter(exec_list_iterator, iter, *instructions) {
  72       ir_instruction *ir = (ir_instruction *)iter.get();
  73
  74       ir_expression_flattening_visitor v(ir, predicate);
  75       ir->accept(&v);
  76    }
  77 }
  78
  79
  80 static ir_rvalue *
  81 operand_to_temp(ir_instruction *base_ir, ir_rvalue *ir)
  82 {
  83    ir_variable *var;
  84    ir_assignment *assign;
  85
  86    var = new ir_variable(ir->type, "flattening_tmp");
  87    base_ir->insert_before(var);
  88
  89    assign = new ir_assignment(new ir_dereference_variable(var),
  90                               ir,
  91                               NULL);
  92    base_ir->insert_before(assign);
  93
  94    return new ir_dereference_variable(var);
  95 }
  96
  97 ir_visitor_status
  98 ir_expression_flattening_visitor::visit_enter(ir_function_signature *ir)
  99 {
 100    do_expression_flattening(&ir->body, this->predicate);
 101
 102    return visit_continue_with_parent;
 103 }
 104
 105 ir_visitor_status
 106 ir_expression_flattening_visitor::visit_enter(ir_loop *ir)
 107 {
 108    do_expression_flattening(&ir->body_instructions, this->predicate);
 109
 110    return visit_continue_with_parent;
 111 }
 112
 113 ir_visitor_status
 114 ir_expression_flattening_visitor::visit_enter(ir_if *ir)
 115 {
 116    ir->condition->accept(this);
 117
 118    do_expression_flattening(&ir->then_instructions, this->predicate);
 119    do_expression_flattening(&ir->else_instructions, this->predicate);
 120
 121    return visit_continue_with_parent;
 122 }
 123
 124 ir_visitor_status
 125 ir_expression_flattening_visitor::visit_leave(ir_expression *ir)
 126 {
 127    unsigned int operand;
 128
 129    for (operand = 0; operand < ir->get_num_operands(); operand++) {
 130       /* If the operand matches the predicate, then we'll assign its
 131        * value to a temporary and deref the temporary as the operand.
 132        */
 133       if (this->predicate(ir->operands[operand])) {
 134          ir->operands[operand] = operand_to_temp(base_ir,
 135                                                  ir->operands[operand]);
 136       }
 137    }
 138
 139    return visit_continue;
 140 }
 141
 142 ir_visitor_status
 143 ir_expression_flattening_visitor::visit_leave(ir_swizzle *ir)
 144 {
 145    if (this->predicate(ir->val)) {
 146       ir->val = operand_to_temp(this->base_ir, ir->val);
 147    }
 148
 149    return visit_continue;
 150 }
 151
 152 ir_visitor_status
 153 ir_expression_flattening_visitor::visit_enter(ir_call *ir)
 154 {
 155    /* FINISHME: Why not process the call parameters? (Same behavior as original
 156     * FINISHME: code.)
 157     */
 158    (void) ir;
 159    return visit_continue_with_parent;
 160 }
 161
 162
 163 ir_visitor_status
 164 ir_expression_flattening_visitor::visit_enter(ir_return *ir)
 165 {
 166    /* FINISHME: Why not process the return value? (Same behavior as original
 167     * FINISHME: code.)
 168     */
 169    (void) ir;
 170    return visit_continue_with_parent;
 171 }