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
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
|
/*
* Copyright © 2015 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.
*/
/*
* Implements a pass that lowers output and/or input variables to a
* temporary plus an output variable with a single copy at each exit
* point of the shader and/or an input variable with a single copy
* at the entrance point of the shader. This way the output variable
* is only ever written once and/or input is only read once, and there
* are no indirect outut/input accesses.
*/
#include "nir.h"
#include "nir_builder.h"
struct lower_io_state {
nir_shader *shader;
nir_function_impl *entrypoint;
struct exec_list old_outputs;
struct exec_list old_inputs;
};
static void
emit_copies(nir_builder *b, struct exec_list *dest_vars,
struct exec_list *src_vars)
{
assert(exec_list_length(dest_vars) == exec_list_length(src_vars));
foreach_two_lists(dest_node, dest_vars, src_node, src_vars) {
nir_variable *dest = exec_node_data(nir_variable, dest_node, node);
nir_variable *src = exec_node_data(nir_variable, src_node, node);
/* No need to copy the contents of a non-fb_fetch_output output variable
* to the temporary allocated for it, since its initial value is
* undefined.
*/
if (src->data.mode == nir_var_shader_out &&
!src->data.fb_fetch_output)
continue;
/* Can't copy the contents of the temporary back to a read-only
* interface variable. The value of the temporary won't have been
* modified by the shader anyway.
*/
if (dest->data.read_only)
continue;
nir_copy_var(b, dest, src);
}
}
static void
emit_output_copies_impl(struct lower_io_state *state, nir_function_impl *impl)
{
nir_builder b;
nir_builder_init(&b, impl);
if (state->shader->info.stage == MESA_SHADER_GEOMETRY) {
/* For geometry shaders, we have to emit the output copies right
* before each EmitVertex call.
*/
nir_foreach_block(block, impl) {
nir_foreach_instr(instr, block) {
if (instr->type != nir_instr_type_intrinsic)
continue;
nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr);
if (intrin->intrinsic == nir_intrinsic_emit_vertex) {
b.cursor = nir_before_instr(&intrin->instr);
emit_copies(&b, &state->shader->outputs, &state->old_outputs);
}
}
}
} else if (impl == state->entrypoint) {
b.cursor = nir_before_block(nir_start_block(impl));
emit_copies(&b, &state->old_outputs, &state->shader->outputs);
/* For all other shader types, we need to do the copies right before
* the jumps to the end block.
*/
struct set_entry *block_entry;
set_foreach(impl->end_block->predecessors, block_entry) {
struct nir_block *block = (void *)block_entry->key;
b.cursor = nir_after_block_before_jump(block);
emit_copies(&b, &state->shader->outputs, &state->old_outputs);
}
}
}
static void
emit_input_copies_impl(struct lower_io_state *state, nir_function_impl *impl)
{
if (impl == state->entrypoint) {
nir_builder b;
nir_builder_init(&b, impl);
b.cursor = nir_before_block(nir_start_block(impl));
emit_copies(&b, &state->old_inputs, &state->shader->inputs);
}
}
static nir_variable *
create_shadow_temp(struct lower_io_state *state, nir_variable *var)
{
nir_variable *nvar = ralloc(state->shader, nir_variable);
memcpy(nvar, var, sizeof *nvar);
/* The original is now the temporary */
nir_variable *temp = var;
/* Reparent the name to the new variable */
ralloc_steal(nvar, nvar->name);
assert(nvar->constant_initializer == NULL);
/* Give the original a new name with @<mode>-temp appended */
const char *mode = (temp->data.mode == nir_var_shader_in) ? "in" : "out";
temp->name = ralloc_asprintf(var, "%s@%s-temp", mode, nvar->name);
temp->data.mode = nir_var_global;
temp->data.read_only = false;
temp->data.fb_fetch_output = false;
temp->data.compact = false;
return nvar;
}
void
nir_lower_io_to_temporaries(nir_shader *shader, nir_function_impl *entrypoint,
bool outputs, bool inputs)
{
struct lower_io_state state;
if (shader->info.stage == MESA_SHADER_TESS_CTRL)
return;
state.shader = shader;
state.entrypoint = entrypoint;
if (inputs)
exec_list_move_nodes_to(&shader->inputs, &state.old_inputs);
else
exec_list_make_empty(&state.old_inputs);
if (outputs)
exec_list_move_nodes_to(&shader->outputs, &state.old_outputs);
else
exec_list_make_empty(&state.old_outputs);
/* Walk over all of the outputs turn each output into a temporary and
* make a new variable for the actual output.
*/
nir_foreach_variable(var, &state.old_outputs) {
nir_variable *output = create_shadow_temp(&state, var);
exec_list_push_tail(&shader->outputs, &output->node);
}
/* and same for inputs: */
nir_foreach_variable(var, &state.old_inputs) {
nir_variable *input = create_shadow_temp(&state, var);
exec_list_push_tail(&shader->inputs, &input->node);
}
nir_foreach_function(function, shader) {
if (function->impl == NULL)
continue;
if (inputs)
emit_input_copies_impl(&state, function->impl);
if (outputs)
emit_output_copies_impl(&state, function->impl);
nir_metadata_preserve(function->impl, nir_metadata_block_index |
nir_metadata_dominance);
}
exec_list_append(&shader->globals, &state.old_inputs);
exec_list_append(&shader->globals, &state.old_outputs);
nir_fixup_deref_modes(shader);
}
|
