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
24 /*
25 * This lowering pass detects when a global variable is only being used by
26 * one function and makes it local to that function
27 */
28
29 #include "nir.h"
30
31 static void
register_var_use(nir_variable * var,nir_function_impl * impl,struct hash_table * var_func_table)32 register_var_use(nir_variable *var, nir_function_impl *impl,
33 struct hash_table *var_func_table)
34 {
35 if (var->data.mode != nir_var_shader_temp)
36 return;
37
38 struct hash_entry *entry =
39 _mesa_hash_table_search(var_func_table, var);
40
41 if (entry) {
42 if (entry->data != impl)
43 entry->data = NULL;
44 } else {
45 _mesa_hash_table_insert(var_func_table, var, impl);
46 }
47 }
48
49 static bool
mark_global_var_uses_block(nir_block * block,nir_function_impl * impl,struct hash_table * var_func_table)50 mark_global_var_uses_block(nir_block *block, nir_function_impl *impl,
51 struct hash_table *var_func_table)
52 {
53 nir_foreach_instr(instr, block) {
54 if (instr->type == nir_instr_type_deref) {
55 nir_deref_instr *deref = nir_instr_as_deref(instr);
56 if (deref->deref_type == nir_deref_type_var)
57 register_var_use(deref->var, impl, var_func_table);
58 }
59 }
60
61 return true;
62 }
63
64 bool
nir_lower_global_vars_to_local(nir_shader * shader)65 nir_lower_global_vars_to_local(nir_shader *shader)
66 {
67 bool progress = false;
68
69 /* A hash table keyed on variable pointers that stores the unique
70 * nir_function_impl that uses the given variable. If a variable is
71 * used in multiple functions, the data for the given key will be NULL.
72 */
73 struct hash_table *var_func_table = _mesa_pointer_hash_table_create(NULL);
74
75 nir_foreach_function_impl(impl, shader) {
76 nir_foreach_block(block, impl)
77 mark_global_var_uses_block(block, impl, var_func_table);
78 }
79
80 nir_foreach_variable_with_modes_safe(var, shader, nir_var_shader_temp) {
81 struct hash_entry *entry = _mesa_hash_table_search(var_func_table, var);
82 if (!entry)
83 continue;
84
85 nir_function_impl *impl = entry->data;
86
87 if (impl != NULL) {
88 exec_node_remove(&var->node);
89 var->data.mode = nir_var_function_temp;
90 exec_list_push_tail(&impl->locals, &var->node);
91 nir_metadata_preserve(impl, nir_metadata_control_flow |
92 nir_metadata_live_defs);
93 progress = true;
94 }
95 }
96
97 _mesa_hash_table_destroy(var_func_table, NULL);
98
99 if (progress)
100 nir_fixup_deref_modes(shader);
101
102 nir_foreach_function_impl(impl, shader) {
103 nir_metadata_preserve(impl, nir_metadata_all);
104 }
105
106 return progress;
107 }
108