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 * Jason Ekstrand (jason@jlekstrand.net)
25 *
26 */
27
28 /*
29 * This lowering pass detects when a global variable is only being used by
30 * one function and makes it local to that function
31 */
32
33 #include "nir.h"
34
35 static bool
mark_global_var_uses_block(nir_block * block,nir_function_impl * impl,struct hash_table * var_func_table)36 mark_global_var_uses_block(nir_block *block, nir_function_impl *impl,
37 struct hash_table *var_func_table)
38 {
39 nir_foreach_instr(instr, block) {
40 if (instr->type != nir_instr_type_intrinsic)
41 continue;
42
43 nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr);
44 unsigned num_vars = nir_intrinsic_infos[intrin->intrinsic].num_variables;
45
46 for (unsigned i = 0; i < num_vars; i++) {
47 nir_variable *var = intrin->variables[i]->var;
48 if (var->data.mode != nir_var_global)
49 continue;
50
51 struct hash_entry *entry =
52 _mesa_hash_table_search(var_func_table, var);
53
54 if (entry) {
55 if (entry->data != impl)
56 entry->data = NULL;
57 } else {
58 _mesa_hash_table_insert(var_func_table, var, impl);
59 }
60 }
61 }
62
63 return true;
64 }
65
66 bool
nir_lower_global_vars_to_local(nir_shader * shader)67 nir_lower_global_vars_to_local(nir_shader *shader)
68 {
69 bool progress = false;
70
71 /* A hash table keyed on variable pointers that stores the unique
72 * nir_function_impl that uses the given variable. If a variable is
73 * used in multiple functions, the data for the given key will be NULL.
74 */
75 struct hash_table *var_func_table =
76 _mesa_hash_table_create(NULL, _mesa_hash_pointer,
77 _mesa_key_pointer_equal);
78
79 nir_foreach_function(function, shader) {
80 if (function->impl) {
81 nir_foreach_block(block, function->impl)
82 mark_global_var_uses_block(block, function->impl, var_func_table);
83 }
84 }
85
86 struct hash_entry *entry;
87 hash_table_foreach(var_func_table, entry) {
88 nir_variable *var = (void *)entry->key;
89 nir_function_impl *impl = entry->data;
90
91 assert(var->data.mode == nir_var_global);
92
93 if (impl != NULL) {
94 exec_node_remove(&var->node);
95 var->data.mode = nir_var_local;
96 exec_list_push_tail(&impl->locals, &var->node);
97 nir_metadata_preserve(impl, nir_metadata_block_index |
98 nir_metadata_dominance |
99 nir_metadata_live_ssa_defs);
100 progress = true;
101 }
102 }
103
104 _mesa_hash_table_destroy(var_func_table, NULL);
105
106 return progress;
107 }
108