1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
|
/*
* Copyright © 2010 Intel Corporation
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice (including the next
* paragraph) shall be included in all copies or substantial portions of the
* Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
* DEALINGS IN THE SOFTWARE.
*/
/**
* \file ir_constant_variable.cpp
*
* Marks variables assigned a single constant value over the course
* of the program as constant.
*
* The goal here is to trigger further constant folding and then dead
* code elimination. This is common with vector/matrix constructors
* and calls to builtin functions.
*/
#include <stdio.h>
#include <stdlib.h>
#include "ir.h"
#include "ir_print_visitor.h"
#include "ir_visitor.h"
#include "ir_optimization.h"
#include "glsl_types.h"
#include "linux_list.h"
struct assignment_entry {
struct list link;
int assignment_count;
ir_variable *var;
ir_constant *constval;
};
class ir_constant_variable_visitor : public ir_hierarchical_visitor {
public:
ir_constant_variable_visitor()
{
list_init(&list);
}
virtual ir_visitor_status visit_enter(ir_assignment *);
struct list list;
};
static struct assignment_entry *
get_assignment_entry(ir_variable *var, struct list *list)
{
struct assignment_entry *entry;
list_foreach_entry(entry, struct assignment_entry, list, link) {
if (entry->var == var)
return entry;
}
entry = (struct assignment_entry *)calloc(1, sizeof(*entry));
entry->var = var;
list_add(&entry->link, list);
return entry;
}
ir_visitor_status
ir_constant_variable_visitor::visit_enter(ir_assignment *ir)
{
ir_constant *constval;
struct assignment_entry *entry;
entry = get_assignment_entry(ir->lhs->variable_referenced(), &this->list);
assert(entry);
entry->assignment_count++;
/* If it's already constant, don't do the work. */
if (entry->var->constant_value)
return visit_continue;
/* OK, now find if we actually have all the right conditions for
* this to be a constant value assigned to the var.
*/
if (ir->condition) {
constval = ir->condition->constant_expression_value();
if (!constval || !constval->value.b[0])
return visit_continue;
}
ir_variable *var = ir->lhs->whole_variable_referenced();
if (!var)
return visit_continue;
constval = ir->rhs->constant_expression_value();
if (!constval)
return visit_continue;
/* Mark this entry as having a constant assignment (if the
* assignment count doesn't go >1). do_constant_variable will fix
* up the variable with the constant value later.
*/
entry->constval = constval;
return visit_continue;
}
/**
* Does a copy propagation pass on the code present in the instruction stream.
*/
bool
do_constant_variable(exec_list *instructions)
{
bool progress = false;
ir_constant_variable_visitor v;
v.run(instructions);
while (!list_is_empty(&v.list)) {
struct assignment_entry *entry;
entry = list_entry(v.list.next, struct assignment_entry, link);
if (entry->assignment_count == 1 && entry->constval) {
entry->var->constant_value = entry->constval;
progress = true;
}
list_del(&entry->link);
free(entry);
}
return progress;
}
bool
do_constant_variable_unlinked(exec_list *instructions)
{
bool progress = false;
foreach_iter(exec_list_iterator, iter, *instructions) {
ir_instruction *ir = (ir_instruction *)iter.get();
ir_function *f = ir->as_function();
if (f) {
foreach_iter(exec_list_iterator, sigiter, *f) {
ir_function_signature *sig =
(ir_function_signature *) sigiter.get();
if (do_constant_variable(&sig->body))
progress = true;
}
}
}
return progress;
}
|
