src/glsl/ir_variable_refcount.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_variable_refcount.cpp
  26  *
  27  * Provides a visitor which produces a list of variables referenced,
  28  * how many times they were referenced and assigned, and whether they
  29  * were defined in the scope.
  30  */
  31
  32 #include "ir.h"
  33 #include "ir_visitor.h"
  34 #include "ir_variable_refcount.h"
  35 #include "glsl_types.h"
  36 #include "util/hash_table.h"
  37
  38 ir_variable_refcount_visitor::ir_variable_refcount_visitor()
  39 {
  40    this->mem_ctx = ralloc_context(NULL);
  41    this->ht = _mesa_hash_table_create(NULL, _mesa_hash_pointer,
  42                                       _mesa_key_pointer_equal);
  43 }
  44
  45 static void
  46 free_entry(struct hash_entry *entry)
  47 {
  48    ir_variable_refcount_entry *ivre = (ir_variable_refcount_entry *) entry->data;
  49    delete ivre;
  50 }
  51
  52 ir_variable_refcount_visitor::~ir_variable_refcount_visitor()
  53 {
  54    ralloc_free(this->mem_ctx);
  55    _mesa_hash_table_destroy(this->ht, free_entry);
  56 }
  57
  58 // constructor
  59 ir_variable_refcount_entry::ir_variable_refcount_entry(ir_variable *var)
  60 {
  61    this->var = var;
  62    assign = NULL;
  63    assigned_count = 0;
  64    declaration = false;
  65    referenced_count = 0;
  66 }
  67
  68
  69 ir_variable_refcount_entry *
  70 ir_variable_refcount_visitor::get_variable_entry(ir_variable *var)
  71 {
  72    assert(var);
  73
  74    struct hash_entry *e = _mesa_hash_table_search(this->ht, var);
  75    if (e)
  76       return (ir_variable_refcount_entry *)e->data;
  77
  78    ir_variable_refcount_entry *entry = new ir_variable_refcount_entry(var);
  79    assert(entry->referenced_count == 0);
  80    _mesa_hash_table_insert(this->ht, var, entry);
  81
  82    return entry;
  83 }
  84
  85
  86 ir_visitor_status
  87 ir_variable_refcount_visitor::visit(ir_variable *ir)
  88 {
  89    ir_variable_refcount_entry *entry = this->get_variable_entry(ir);
  90    if (entry)
  91       entry->declaration = true;
  92
  93    return visit_continue;
  94 }
  95
  96
  97 ir_visitor_status
  98 ir_variable_refcount_visitor::visit(ir_dereference_variable *ir)
  99 {
 100    ir_variable *const var = ir->variable_referenced();
 101    ir_variable_refcount_entry *entry = this->get_variable_entry(var);
 102
 103    if (entry)
 104       entry->referenced_count++;
 105
 106    return visit_continue;
 107 }
 108
 109
 110 ir_visitor_status
 111 ir_variable_refcount_visitor::visit_enter(ir_function_signature *ir)
 112 {
 113    /* We don't want to descend into the function parameters and
 114     * dead-code eliminate them, so just accept the body here.
 115     */
 116    visit_list_elements(this, &ir->body);
 117    return visit_continue_with_parent;
 118 }
 119
 120
 121 ir_visitor_status
 122 ir_variable_refcount_visitor::visit_leave(ir_assignment *ir)
 123 {
 124    ir_variable_refcount_entry *entry;
 125    entry = this->get_variable_entry(ir->lhs->variable_referenced());
 126    if (entry) {
 127       entry->assigned_count++;
 128       if (entry->assign == NULL)
 129          entry->assign = ir;
 130    }
 131
 132    return visit_continue;
 133 }