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 opt_dead_functions.cpp
26 *
27 * Eliminates unused functions from the linked program.
28 */
29
30#include "ir.h"
31#include "ir_visitor.h"
32#include "ir_expression_flattening.h"
33#include "compiler/glsl_types.h"
34
35namespace {
36
37class signature_entry : public exec_node
38{
39public:
40   signature_entry(ir_function_signature *sig)
41   {
42      this->signature = sig;
43      this->used = false;
44   }
45
46   ir_function_signature *signature;
47   bool used;
48};
49
50class ir_dead_functions_visitor : public ir_hierarchical_visitor {
51public:
52   ir_dead_functions_visitor()
53   {
54      this->mem_ctx = ralloc_context(NULL);
55   }
56
57   ~ir_dead_functions_visitor()
58   {
59      ralloc_free(this->mem_ctx);
60   }
61
62   virtual ir_visitor_status visit_enter(ir_function_signature *);
63   virtual ir_visitor_status visit_enter(ir_call *);
64
65   signature_entry *get_signature_entry(ir_function_signature *var);
66
67   /* List of signature_entry */
68   exec_list signature_list;
69   void *mem_ctx;
70};
71
72} /* unnamed namespace */
73
74signature_entry *
75ir_dead_functions_visitor::get_signature_entry(ir_function_signature *sig)
76{
77   foreach_in_list(signature_entry, entry, &this->signature_list) {
78      if (entry->signature == sig)
79	 return entry;
80   }
81
82   signature_entry *entry = new(mem_ctx) signature_entry(sig);
83   this->signature_list.push_tail(entry);
84   return entry;
85}
86
87
88ir_visitor_status
89ir_dead_functions_visitor::visit_enter(ir_function_signature *ir)
90{
91   signature_entry *entry = this->get_signature_entry(ir);
92
93   if (strcmp(ir->function_name(), "main") == 0) {
94      entry->used = true;
95   }
96
97
98
99   return visit_continue;
100}
101
102
103ir_visitor_status
104ir_dead_functions_visitor::visit_enter(ir_call *ir)
105{
106   signature_entry *entry = this->get_signature_entry(ir->callee);
107
108   entry->used = true;
109
110   return visit_continue;
111}
112
113bool
114do_dead_functions(exec_list *instructions)
115{
116   ir_dead_functions_visitor v;
117   bool progress = false;
118
119   visit_list_elements(&v, instructions);
120
121   /* Now that we've figured out which function signatures are used, remove
122    * the unused ones, and remove function definitions that have no more
123    * signatures.
124    */
125    foreach_in_list_safe(signature_entry, entry, &v.signature_list) {
126      if (!entry->used) {
127	 entry->signature->remove();
128	 delete entry->signature;
129	 progress = true;
130      }
131      delete(entry);
132   }
133
134   /* We don't just do this above when we nuked a signature because of
135    * const pointers.
136    */
137   foreach_in_list_safe(ir_instruction, ir, instructions) {
138      ir_function *func = ir->as_function();
139
140      if (func && func->signatures.is_empty()) {
141	 /* At this point (post-linking), the symbol table is no
142	  * longer in use, so not removing the function from the
143	  * symbol table should be OK.
144	  */
145	 func->remove();
146	 delete func;
147	 progress = true;
148      }
149   }
150
151   return progress;
152}
153