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
166
167
168
169
|
/*
* 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 opt_dead_code.cpp
*
* Eliminates dead assignments and variable declarations from the code.
*/
#include "ir.h"
#include "ir_visitor.h"
#include "ir_variable_refcount.h"
#include "glsl_types.h"
#include "util/hash_table.h"
static bool debug = false;
/**
* Do a dead code pass over instructions and everything that instructions
* references.
*
* Note that this will remove assignments to globals, so it is not suitable
* for usage on an unlinked instruction stream.
*/
bool
do_dead_code(exec_list *instructions, bool uniform_locations_assigned)
{
ir_variable_refcount_visitor v;
bool progress = false;
v.run(instructions);
struct hash_entry *e;
hash_table_foreach(v.ht, e) {
ir_variable_refcount_entry *entry = (ir_variable_refcount_entry *)e->data;
/* Since each assignment is a reference, the refereneced count must be
* greater than or equal to the assignment count. If they are equal,
* then all of the references are assignments, and the variable is
* dead.
*
* Note that if the variable is neither assigned nor referenced, both
* counts will be zero and will be caught by the equality test.
*/
assert(entry->referenced_count >= entry->assigned_count);
if (debug) {
printf("%s@%p: %d refs, %d assigns, %sdeclared in our scope\n",
entry->var->name, (void *) entry->var,
entry->referenced_count, entry->assigned_count,
entry->declaration ? "" : "not ");
}
if ((entry->referenced_count > entry->assigned_count)
|| !entry->declaration)
continue;
if (entry->assign) {
/* Remove a single dead assignment to the variable we found.
* Don't do so if it's a shader or function output, though.
*/
if (entry->var->data.mode != ir_var_function_out &&
entry->var->data.mode != ir_var_function_inout &&
entry->var->data.mode != ir_var_shader_out) {
entry->assign->remove();
progress = true;
if (debug) {
printf("Removed assignment to %s@%p\n",
entry->var->name, (void *) entry->var);
}
}
} else {
/* If there are no assignments or references to the variable left,
* then we can remove its declaration.
*/
/* uniform initializers are precious, and could get used by another
* stage. Also, once uniform locations have been assigned, the
* declaration cannot be deleted.
*/
if (entry->var->data.mode == ir_var_uniform) {
if (uniform_locations_assigned || entry->var->constant_value)
continue;
/* Section 2.11.6 (Uniform Variables) of the OpenGL ES 3.0.3 spec
* says:
*
* "All members of a named uniform block declared with a
* shared or std140 layout qualifier are considered active,
* even if they are not referenced in any shader in the
* program. The uniform block itself is also considered
* active, even if no member of the block is referenced."
*
* If the variable is in a uniform block with one of those
* layouts, do not eliminate it.
*/
if (entry->var->is_in_uniform_block()) {
const glsl_type *const block_type =
entry->var->is_interface_instance()
? entry->var->type : entry->var->get_interface_type();
if (block_type->interface_packing != GLSL_INTERFACE_PACKING_PACKED)
continue;
}
}
entry->var->remove();
progress = true;
if (debug) {
printf("Removed declaration of %s@%p\n",
entry->var->name, (void *) entry->var);
}
}
}
return progress;
}
/**
* Does a dead code pass on the functions present in the instruction stream.
*
* This is suitable for use while the program is not linked, as it will
* ignore variable declarations (and the assignments to them) for variables
* with global scope.
*/
bool
do_dead_code_unlinked(exec_list *instructions)
{
bool progress = false;
foreach_in_list(ir_instruction, ir, instructions) {
ir_function *f = ir->as_function();
if (f) {
foreach_in_list(ir_function_signature, sig, &f->signatures) {
/* The setting of the uniform_locations_assigned flag here is
* irrelevent. If there is a uniform declaration encountered
* inside the body of the function, something has already gone
* terribly, terribly wrong.
*/
if (do_dead_code(&sig->body, false))
progress = true;
}
}
}
return progress;
}
|
