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 void
register_var_use(nir_variable * var,nir_function_impl * impl,struct hash_table * var_func_table)36 register_var_use(nir_variable *var, nir_function_impl *impl,
37 struct hash_table *var_func_table)
38 {
39 if (var->data.mode != nir_var_shader_temp)
40 return;
41
42 struct hash_entry *entry =
43 _mesa_hash_table_search(var_func_table, var);
44
45 if (entry) {
46 if (entry->data != impl)
47 entry->data = NULL;
48 } else {
49 _mesa_hash_table_insert(var_func_table, var, impl);
50 }
51 }
52
53 static bool
mark_global_var_uses_block(nir_block * block,nir_function_impl * impl,struct hash_table * var_func_table)54 mark_global_var_uses_block(nir_block *block, nir_function_impl *impl,
55 struct hash_table *var_func_table)
56 {
57 nir_foreach_instr(instr, block) {
58 if (instr->type == nir_instr_type_deref) {
59 nir_deref_instr *deref = nir_instr_as_deref(instr);
60 if (deref->deref_type == nir_deref_type_var)
61 register_var_use(deref->var, impl, var_func_table);
62 }
63 }
64
65 return true;
66 }
67
68 bool
nir_lower_global_vars_to_local(nir_shader * shader)69 nir_lower_global_vars_to_local(nir_shader *shader)
70 {
71 bool progress = false;
72
73 /* A hash table keyed on variable pointers that stores the unique
74 * nir_function_impl that uses the given variable. If a variable is
75 * used in multiple functions, the data for the given key will be NULL.
76 */
77 struct hash_table *var_func_table = _mesa_pointer_hash_table_create(NULL);
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 nir_foreach_variable_with_modes_safe(var, shader, nir_var_shader_temp) {
87 struct hash_entry *entry = _mesa_hash_table_search(var_func_table, var);
88 if (!entry)
89 continue;
90
91 nir_function_impl *impl = entry->data;
92
93 if (impl != NULL) {
94 exec_node_remove(&var->node);
95 var->data.mode = nir_var_function_temp;
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 if (progress)
107 nir_fixup_deref_modes(shader);
108
109 nir_foreach_function(function, shader) {
110 if (function->impl)
111 nir_metadata_preserve(function->impl, nir_metadata_all);
112 }
113
114 return progress;
115 }
116