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