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 © 2012 Vincent Lejeune
* Copyright © 2012 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.
*/
#include "ir.h"
#include "program/hash_table.h"
/**
* \file lower_output_reads.cpp
*
* In GLSL, shader output variables (such as varyings) can be both read and
* written. However, on some hardware, reading an output register causes
* trouble.
*
* This pass creates temporary shadow copies of every (used) shader output,
* and replaces all accesses to use those instead. It also adds code to the
* main() function to copy the final values to the actual shader outputs.
*/
class output_read_remover : public ir_hierarchical_visitor {
protected:
/**
* A hash table mapping from the original ir_variable shader outputs
* (ir_var_shader_out mode) to the new temporaries to be used instead.
*/
hash_table *replacements;
void *mem_ctx;
public:
output_read_remover();
~output_read_remover();
virtual ir_visitor_status visit(class ir_dereference_variable *);
virtual ir_visitor_status visit(class ir_emit_vertex *);
virtual ir_visitor_status visit_leave(class ir_return *);
virtual ir_visitor_status visit_leave(class ir_function_signature *);
};
/**
* Hash function for the output variables - computes the hash of the name.
* NOTE: We're using the name string to ensure that the hash doesn't depend
* on any random factors, otherwise the output_read_remover could produce
* the random order of the assignments.
*
* NOTE: If you want to reuse this function please take into account that
* generally the names of the variables are non-unique.
*/
static unsigned
hash_table_var_hash(const void *key)
{
const ir_variable * var = static_cast<const ir_variable *>(key);
return hash_table_string_hash(var->name);
}
output_read_remover::output_read_remover()
{
mem_ctx = ralloc_context(NULL);
replacements =
hash_table_ctor(0, hash_table_var_hash, hash_table_pointer_compare);
}
output_read_remover::~output_read_remover()
{
hash_table_dtor(replacements);
ralloc_free(mem_ctx);
}
ir_visitor_status
output_read_remover::visit(ir_dereference_variable *ir)
{
if (ir->var->mode != ir_var_shader_out)
return visit_continue;
ir_variable *temp = (ir_variable *) hash_table_find(replacements, ir->var);
/* If we don't have an existing temporary, create one. */
if (temp == NULL) {
void *var_ctx = ralloc_parent(ir->var);
temp = new(var_ctx) ir_variable(ir->var->type, ir->var->name,
ir_var_temporary);
hash_table_insert(replacements, temp, ir->var);
ir->var->insert_after(temp);
}
/* Update the dereference to use the temporary */
ir->var = temp;
return visit_continue;
}
/**
* Create an assignment to copy a temporary value back to the actual output.
*/
static ir_assignment *
copy(void *ctx, ir_variable *output, ir_variable *temp)
{
ir_dereference_variable *lhs = new(ctx) ir_dereference_variable(output);
ir_dereference_variable *rhs = new(ctx) ir_dereference_variable(temp);
return new(ctx) ir_assignment(lhs, rhs);
}
/** Insert a copy-back assignment before a "return" statement or a call to
* EmitVertex().
*/
static void
emit_return_copy(const void *key, void *data, void *closure)
{
ir_return *ir = (ir_return *) closure;
ir->insert_before(copy(ir, (ir_variable *) key, (ir_variable *) data));
}
/** Insert a copy-back assignment at the end of the main() function */
static void
emit_main_copy(const void *key, void *data, void *closure)
{
ir_function_signature *sig = (ir_function_signature *) closure;
sig->body.push_tail(copy(sig, (ir_variable *) key, (ir_variable *) data));
}
ir_visitor_status
output_read_remover::visit_leave(ir_return *ir)
{
hash_table_call_foreach(replacements, emit_return_copy, ir);
return visit_continue;
}
ir_visitor_status
output_read_remover::visit(ir_emit_vertex *ir)
{
hash_table_call_foreach(replacements, emit_return_copy, ir);
hash_table_clear(replacements);
return visit_continue;
}
ir_visitor_status
output_read_remover::visit_leave(ir_function_signature *sig)
{
if (strcmp(sig->function_name(), "main") != 0)
return visit_continue;
hash_table_call_foreach(replacements, emit_main_copy, sig);
return visit_continue;
}
void
lower_output_reads(exec_list *instructions)
{
output_read_remover v;
visit_list_elements(&v, instructions);
}
|
