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