1 /*
2 * Copyright © 2014 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 DEALINGS
21 * IN THE SOFTWARE.
22 *
23 * Authors:
24 * Connor Abbott (cwabbott0@gmail.com)
25 *
26 */
27
28 #include "nir.h"
29
30 static void
add_var_use_intrinsic(nir_intrinsic_instr * instr,struct set * live,nir_variable_mode modes)31 add_var_use_intrinsic(nir_intrinsic_instr *instr, struct set *live,
32 nir_variable_mode modes)
33 {
34 unsigned num_vars = nir_intrinsic_infos[instr->intrinsic].num_variables;
35
36 switch (instr->intrinsic) {
37 case nir_intrinsic_copy_var:
38 _mesa_set_add(live, instr->variables[1]->var);
39 /* Fall through */
40 case nir_intrinsic_store_var: {
41 /* The first source in both copy_var and store_var is the destination.
42 * If the variable is a local that never escapes the shader, then we
43 * don't mark it as live for just a store.
44 */
45 nir_variable_mode mode = instr->variables[0]->var->data.mode;
46 if (!(mode & (nir_var_local | nir_var_global | nir_var_shared)))
47 _mesa_set_add(live, instr->variables[0]->var);
48 break;
49 }
50
51 /* This pass can't be used on I/O variables after they've been lowered. */
52 case nir_intrinsic_load_input:
53 assert(!(modes & nir_var_shader_in));
54 break;
55 case nir_intrinsic_store_output:
56 assert(!(modes & nir_var_shader_out));
57 break;
58
59 default:
60 for (unsigned i = 0; i < num_vars; i++) {
61 _mesa_set_add(live, instr->variables[i]->var);
62 }
63 break;
64 }
65 }
66
67 static void
add_var_use_call(nir_call_instr * instr,struct set * live)68 add_var_use_call(nir_call_instr *instr, struct set *live)
69 {
70 if (instr->return_deref != NULL) {
71 nir_variable *var = instr->return_deref->var;
72 _mesa_set_add(live, var);
73 }
74
75 for (unsigned i = 0; i < instr->num_params; i++) {
76 nir_variable *var = instr->params[i]->var;
77 _mesa_set_add(live, var);
78 }
79 }
80
81 static void
add_var_use_tex(nir_tex_instr * instr,struct set * live)82 add_var_use_tex(nir_tex_instr *instr, struct set *live)
83 {
84 if (instr->texture != NULL) {
85 nir_variable *var = instr->texture->var;
86 _mesa_set_add(live, var);
87 }
88
89 if (instr->sampler != NULL) {
90 nir_variable *var = instr->sampler->var;
91 _mesa_set_add(live, var);
92 }
93 }
94
95 static void
add_var_use_shader(nir_shader * shader,struct set * live,nir_variable_mode modes)96 add_var_use_shader(nir_shader *shader, struct set *live, nir_variable_mode modes)
97 {
98 nir_foreach_function(function, shader) {
99 if (function->impl) {
100 nir_foreach_block(block, function->impl) {
101 nir_foreach_instr(instr, block) {
102 switch(instr->type) {
103 case nir_instr_type_intrinsic:
104 add_var_use_intrinsic(nir_instr_as_intrinsic(instr), live,
105 modes);
106 break;
107
108 case nir_instr_type_call:
109 add_var_use_call(nir_instr_as_call(instr), live);
110 break;
111
112 case nir_instr_type_tex:
113 add_var_use_tex(nir_instr_as_tex(instr), live);
114 break;
115
116 default:
117 break;
118 }
119 }
120 }
121 }
122 }
123 }
124
125 static void
remove_dead_var_writes(nir_shader * shader,struct set * live)126 remove_dead_var_writes(nir_shader *shader, struct set *live)
127 {
128 nir_foreach_function(function, shader) {
129 if (!function->impl)
130 continue;
131
132 nir_foreach_block(block, function->impl) {
133 nir_foreach_instr_safe(instr, block) {
134 if (instr->type != nir_instr_type_intrinsic)
135 continue;
136
137 nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr);
138 if (intrin->intrinsic != nir_intrinsic_copy_var &&
139 intrin->intrinsic != nir_intrinsic_store_var)
140 continue;
141
142 /* Stores to dead variables need to be removed */
143 if (intrin->variables[0]->var->data.mode == 0)
144 nir_instr_remove(instr);
145 }
146 }
147 }
148 }
149
150 static bool
remove_dead_vars(struct exec_list * var_list,struct set * live)151 remove_dead_vars(struct exec_list *var_list, struct set *live)
152 {
153 bool progress = false;
154
155 foreach_list_typed_safe(nir_variable, var, node, var_list) {
156 struct set_entry *entry = _mesa_set_search(live, var);
157 if (entry == NULL) {
158 /* Mark this variable as used by setting the mode to 0 */
159 var->data.mode = 0;
160 exec_node_remove(&var->node);
161 progress = true;
162 }
163 }
164
165 return progress;
166 }
167
168 bool
nir_remove_dead_variables(nir_shader * shader,nir_variable_mode modes)169 nir_remove_dead_variables(nir_shader *shader, nir_variable_mode modes)
170 {
171 bool progress = false;
172 struct set *live =
173 _mesa_set_create(NULL, _mesa_hash_pointer, _mesa_key_pointer_equal);
174
175 add_var_use_shader(shader, live, modes);
176
177 if (modes & nir_var_uniform)
178 progress = remove_dead_vars(&shader->uniforms, live) || progress;
179
180 if (modes & nir_var_shader_in)
181 progress = remove_dead_vars(&shader->inputs, live) || progress;
182
183 if (modes & nir_var_shader_out)
184 progress = remove_dead_vars(&shader->outputs, live) || progress;
185
186 if (modes & nir_var_global)
187 progress = remove_dead_vars(&shader->globals, live) || progress;
188
189 if (modes & nir_var_system_value)
190 progress = remove_dead_vars(&shader->system_values, live) || progress;
191
192 if (modes & nir_var_shared)
193 progress = remove_dead_vars(&shader->shared, live) || progress;
194
195 if (modes & nir_var_local) {
196 nir_foreach_function(function, shader) {
197 if (function->impl) {
198 if (remove_dead_vars(&function->impl->locals, live))
199 progress = true;
200 }
201 }
202 }
203
204 if (progress) {
205 remove_dead_var_writes(shader, live);
206
207 nir_foreach_function(function, shader) {
208 if (function->impl) {
209 nir_metadata_preserve(function->impl, nir_metadata_block_index |
210 nir_metadata_dominance);
211 }
212 }
213 }
214
215 _mesa_set_destroy(live, NULL);
216 return progress;
217 }
218