1 /*
2 * Copyright © 2018 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
24 #include "nir.h"
25 #include "nir_deref.h"
26
27 struct split_struct_state {
28 void *dead_ctx;
29
30 struct hash_table *var_to_member_map;
31 };
32
33 static nir_variable *
find_var_member(struct nir_variable * var,unsigned member,struct hash_table * var_to_member_map)34 find_var_member(struct nir_variable *var, unsigned member,
35 struct hash_table *var_to_member_map)
36 {
37 struct hash_entry *map_entry =
38 _mesa_hash_table_search(var_to_member_map, var);
39 if (map_entry == NULL)
40 return NULL;
41
42 nir_variable **members = map_entry->data;
43 assert(member < var->num_members);
44 return members[member];
45 }
46
47 static const struct glsl_type *
member_type(const struct glsl_type * type,unsigned index)48 member_type(const struct glsl_type *type, unsigned index)
49 {
50 if (glsl_type_is_array(type)) {
51 const struct glsl_type *elem =
52 member_type(glsl_get_array_element(type), index);
53 assert(glsl_get_explicit_stride(type) == 0);
54 return glsl_array_type(elem, glsl_get_length(type), 0);
55 } else {
56 assert(glsl_type_is_struct_or_ifc(type));
57 assert(index < glsl_get_length(type));
58 return glsl_get_struct_field(type, index);
59 }
60 }
61
62 static void
split_variable(struct nir_variable * var,nir_shader * shader,struct hash_table * var_to_member_map,void * dead_ctx)63 split_variable(struct nir_variable *var, nir_shader *shader,
64 struct hash_table *var_to_member_map, void *dead_ctx)
65 {
66 assert(var->state_slots == NULL);
67
68 /* Constant initializers are currently not handled */
69 assert(var->constant_initializer == NULL && var->pointer_initializer == NULL);
70
71 nir_variable **members =
72 ralloc_array(dead_ctx, nir_variable *, var->num_members);
73
74 for (unsigned i = 0; i < var->num_members; i++) {
75 char *member_name = NULL;
76 if (var->name) {
77 /* Calculate a reasonable variable name */
78 member_name = ralloc_strdup(dead_ctx, var->name);
79 const struct glsl_type *t = var->type;
80 while (glsl_type_is_array(t)) {
81 ralloc_strcat(&member_name, "[*]");
82 t = glsl_get_array_element(t);
83 }
84 const char *field_name = glsl_get_struct_elem_name(t, i);
85 if (field_name) {
86 member_name = ralloc_asprintf(dead_ctx, "%s.%s",
87 member_name, field_name);
88 } else {
89 member_name = ralloc_asprintf(dead_ctx, "%s.@%d", member_name, i);
90 }
91 }
92
93 members[i] =
94 nir_variable_create(shader, var->members[i].mode,
95 member_type(var->type, i), member_name);
96 if (var->interface_type) {
97 members[i]->interface_type =
98 glsl_get_struct_field(var->interface_type, i);
99 }
100 members[i]->data = var->members[i];
101 }
102
103 _mesa_hash_table_insert(var_to_member_map, var, members);
104 }
105
106 static nir_deref_instr *
build_member_deref(nir_builder * b,nir_deref_instr * deref,nir_variable * member)107 build_member_deref(nir_builder *b, nir_deref_instr *deref, nir_variable *member)
108 {
109 if (deref->deref_type == nir_deref_type_var) {
110 return nir_build_deref_var(b, member);
111 } else {
112 nir_deref_instr *parent =
113 build_member_deref(b, nir_deref_instr_parent(deref), member);
114 return nir_build_deref_follower(b, parent, deref);
115 }
116 }
117
118 static void
rewrite_deref_instr(nir_builder * b,nir_deref_instr * deref,struct hash_table * var_to_member_map)119 rewrite_deref_instr(nir_builder *b, nir_deref_instr *deref,
120 struct hash_table *var_to_member_map)
121 {
122 /* We must be a struct deref */
123 if (deref->deref_type != nir_deref_type_struct)
124 return;
125
126 nir_deref_instr *base;
127 for (base = nir_deref_instr_parent(deref);
128 base && base->deref_type != nir_deref_type_var;
129 base = nir_deref_instr_parent(base)) {
130
131 /* If this struct is nested inside another, bail */
132 if (base->deref_type == nir_deref_type_struct)
133 return;
134 }
135
136 /* We must be on a variable with members */
137 if (!base || base->var->num_members == 0)
138 return;
139
140 nir_variable *member = find_var_member(base->var, deref->strct.index,
141 var_to_member_map);
142 assert(member);
143
144 b->cursor = nir_before_instr(&deref->instr);
145 nir_deref_instr *member_deref =
146 build_member_deref(b, nir_deref_instr_parent(deref), member);
147 nir_ssa_def_rewrite_uses(&deref->dest.ssa,
148 &member_deref->dest.ssa);
149
150 /* The referenced variable is no longer valid, clean up the deref */
151 nir_deref_instr_remove_if_unused(deref);
152 }
153
154 bool
nir_split_per_member_structs(nir_shader * shader)155 nir_split_per_member_structs(nir_shader *shader)
156 {
157 bool progress = false;
158 void *dead_ctx = ralloc_context(NULL);
159 struct hash_table *var_to_member_map =
160 _mesa_pointer_hash_table_create(dead_ctx);
161
162 nir_foreach_variable_with_modes_safe(var, shader, nir_var_shader_in |
163 nir_var_shader_out |
164 nir_var_system_value) {
165 if (var->num_members == 0)
166 continue;
167
168 split_variable(var, shader, var_to_member_map, dead_ctx);
169 exec_node_remove(&var->node);
170 progress = true;
171 }
172
173 if (!progress) {
174 ralloc_free(dead_ctx);
175 return false;
176 }
177
178 nir_foreach_function(function, shader) {
179 if (!function->impl)
180 continue;
181
182 nir_builder b;
183 nir_builder_init(&b, function->impl);
184 nir_foreach_block(block, function->impl) {
185 nir_foreach_instr_safe(instr, block) {
186 if (instr->type == nir_instr_type_deref) {
187 rewrite_deref_instr(&b, nir_instr_as_deref(instr),
188 var_to_member_map);
189 }
190 }
191 }
192
193 nir_metadata_preserve(function->impl,
194 nir_metadata_block_index |
195 nir_metadata_dominance);
196 }
197
198 ralloc_free(dead_ctx);
199
200 return progress;
201 }
202