src/glsl/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_assignment *);
  61    virtual ir_visitor_status visit_leave(ir_expression *);
  62    virtual ir_visitor_status visit_leave(ir_swizzle *);
  63
  64    ir_rvalue *operand_to_temp(ir_rvalue *val);
  65    bool (*predicate)(ir_instruction *ir);
  66    ir_instruction *base_ir;
  67 };
  68
  69 void
  70 do_expression_flattening(exec_list *instructions,
  71                          bool (*predicate)(ir_instruction *ir))
  72 {
  73    foreach_iter(exec_list_iterator, iter, *instructions) {
  74       ir_instruction *ir = (ir_instruction *)iter.get();
  75
  76       ir_expression_flattening_visitor v(ir, predicate);
  77       ir->accept(&v);
  78    }
  79 }
  80
  81
  82 ir_rvalue *
  83 ir_expression_flattening_visitor::operand_to_temp(ir_rvalue *ir)
  84 {
  85    void *ctx = base_ir;
  86    ir_variable *var;
  87    ir_assignment *assign;
  88
  89    if (!this->predicate(ir))
  90       return ir;
  91
  92    var = new(ctx) ir_variable(ir->type, "flattening_tmp", ir_var_temporary);
  93    base_ir->insert_before(var);
  94
  95    assign = new(ctx) ir_assignment(new(ctx) ir_dereference_variable(var),
  96                                    ir,
  97                                    NULL);
  98    base_ir->insert_before(assign);
  99
 100    return new(ctx) ir_dereference_variable(var);
 101 }
 102
 103 ir_visitor_status
 104 ir_expression_flattening_visitor::visit_enter(ir_function_signature *ir)
 105 {
 106    do_expression_flattening(&ir->body, this->predicate);
 107
 108    return visit_continue_with_parent;
 109 }
 110
 111 ir_visitor_status
 112 ir_expression_flattening_visitor::visit_enter(ir_loop *ir)
 113 {
 114    do_expression_flattening(&ir->body_instructions, this->predicate);
 115
 116    return visit_continue_with_parent;
 117 }
 118
 119 ir_visitor_status
 120 ir_expression_flattening_visitor::visit_enter(ir_if *ir)
 121 {
 122    ir->condition->accept(this);
 123
 124    do_expression_flattening(&ir->then_instructions, this->predicate);
 125    do_expression_flattening(&ir->else_instructions, this->predicate);
 126
 127    return visit_continue_with_parent;
 128 }
 129
 130 ir_visitor_status
 131 ir_expression_flattening_visitor::visit_leave(ir_expression *ir)
 132 {
 133    unsigned int operand;
 134
 135    for (operand = 0; operand < ir->get_num_operands(); operand++) {
 136       /* If the operand matches the predicate, then we'll assign its
 137        * value to a temporary and deref the temporary as the operand.
 138        */
 139       ir->operands[operand] = operand_to_temp(ir->operands[operand]);
 140    }
 141
 142    return visit_continue;
 143 }
 144
 145 ir_visitor_status
 146 ir_expression_flattening_visitor::visit_leave(ir_assignment *ir)
 147 {
 148    ir->rhs = operand_to_temp(ir->rhs);
 149    if (ir->condition)
 150       ir->condition = operand_to_temp(ir->condition);
 151
 152    return visit_continue;
 153 }
 154
 155 ir_visitor_status
 156 ir_expression_flattening_visitor::visit_leave(ir_swizzle *ir)
 157 {
 158    if (this->predicate(ir->val)) {
 159       ir->val = operand_to_temp(ir->val);
 160    }
 161
 162    return visit_continue;
 163 }
 164
 165 ir_visitor_status
 166 ir_expression_flattening_visitor::visit_enter(ir_call *ir)
 167 {
 168    /* Reminder: iterating ir_call iterates its parameters. */
 169    foreach_iter(exec_list_iterator, iter, *ir) {
 170       ir_rvalue *ir = (ir_rvalue *)iter.get();
 171       ir_rvalue *new_ir = operand_to_temp(ir);
 172
 173       if (new_ir != ir) {
 174          ir->replace_with(new_ir);
 175       }
 176    }
 177
 178    return visit_continue;
 179 }
 180
 181
 182 ir_visitor_status
 183 ir_expression_flattening_visitor::visit_enter(ir_return *ir)
 184 {
 185    if (ir->value)
 186       ir->value = operand_to_temp(ir->value);
 187    return visit_continue;
 188 }