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 "compiler/glsl_types.h"
36 #include "util/hash_table.h"
37
ir_variable_refcount_visitor()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
free_entry(struct hash_entry * entry)46 free_entry(struct hash_entry *entry)
47 {
48 ir_variable_refcount_entry *ivre = (ir_variable_refcount_entry *) entry->data;
49
50 /* Free assignment list */
51 exec_node *n;
52 while ((n = ivre->assign_list.pop_head()) != NULL) {
53 struct assignment_entry *assignment_entry =
54 exec_node_data(struct assignment_entry, n, link);
55 free(assignment_entry);
56 }
57
58 delete ivre;
59 }
60
~ir_variable_refcount_visitor()61 ir_variable_refcount_visitor::~ir_variable_refcount_visitor()
62 {
63 ralloc_free(this->mem_ctx);
64 _mesa_hash_table_destroy(this->ht, free_entry);
65 }
66
67 // constructor
ir_variable_refcount_entry(ir_variable * var)68 ir_variable_refcount_entry::ir_variable_refcount_entry(ir_variable *var)
69 {
70 this->var = var;
71 assigned_count = 0;
72 declaration = false;
73 referenced_count = 0;
74 }
75
76
77 ir_variable_refcount_entry *
get_variable_entry(ir_variable * var)78 ir_variable_refcount_visitor::get_variable_entry(ir_variable *var)
79 {
80 assert(var);
81
82 struct hash_entry *e = _mesa_hash_table_search(this->ht, var);
83 if (e)
84 return (ir_variable_refcount_entry *)e->data;
85
86 ir_variable_refcount_entry *entry = new ir_variable_refcount_entry(var);
87 assert(entry->referenced_count == 0);
88 _mesa_hash_table_insert(this->ht, var, entry);
89
90 return entry;
91 }
92
93
94 ir_visitor_status
visit(ir_variable * ir)95 ir_variable_refcount_visitor::visit(ir_variable *ir)
96 {
97 ir_variable_refcount_entry *entry = this->get_variable_entry(ir);
98 if (entry)
99 entry->declaration = true;
100
101 return visit_continue;
102 }
103
104
105 ir_visitor_status
visit(ir_dereference_variable * ir)106 ir_variable_refcount_visitor::visit(ir_dereference_variable *ir)
107 {
108 ir_variable *const var = ir->variable_referenced();
109 ir_variable_refcount_entry *entry = this->get_variable_entry(var);
110
111 if (entry)
112 entry->referenced_count++;
113
114 return visit_continue;
115 }
116
117
118 ir_visitor_status
visit_enter(ir_function_signature * ir)119 ir_variable_refcount_visitor::visit_enter(ir_function_signature *ir)
120 {
121 /* We don't want to descend into the function parameters and
122 * dead-code eliminate them, so just accept the body here.
123 */
124 visit_list_elements(this, &ir->body);
125 return visit_continue_with_parent;
126 }
127
128
129 ir_visitor_status
visit_leave(ir_assignment * ir)130 ir_variable_refcount_visitor::visit_leave(ir_assignment *ir)
131 {
132 ir_variable_refcount_entry *entry;
133 entry = this->get_variable_entry(ir->lhs->variable_referenced());
134 if (entry) {
135 entry->assigned_count++;
136
137 /* Build a list for dead code optimisation. Don't add assignment if it
138 * was declared out of scope (outside the instruction stream). Also don't
139 * bother adding any more to the list if there are more references than
140 * assignments as this means the variable is used and won't be optimised
141 * out.
142 */
143 assert(entry->referenced_count >= entry->assigned_count);
144 if (entry->referenced_count == entry->assigned_count) {
145 struct assignment_entry *assignment_entry =
146 (struct assignment_entry *)calloc(1, sizeof(*assignment_entry));
147 assignment_entry->assign = ir;
148 entry->assign_list.push_head(&assignment_entry->link);
149 }
150 }
151
152 return visit_continue;
153 }
154