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github.com/openbsd/xenocara
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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#include "nir_instr_set.h"
25
26/*
27 * Implements common subexpression elimination
28 */
29
30static bool
31dominates(const nir_instr *old_instr, const nir_instr *new_instr)
32{
33 return nir_block_dominates(old_instr->block, new_instr->block);
34}
35
36static bool
37nir_opt_cse_impl(nir_function_impl *impl)
38{
39 struct set *instr_set = nir_instr_set_create(NULL);
40
41 _mesa_set_resize(instr_set, impl->ssa_alloc);
42
43 nir_metadata_require(impl, nir_metadata_dominance);
44
45 bool progress = false;
46 nir_foreach_block(block, impl) {
47 nir_foreach_instr_safe(instr, block) {
48 if (nir_instr_set_add_or_rewrite(instr_set, instr, dominates)) {
49 progress = true;
50 nir_instr_remove(instr);
51 }
52 }
53 }
54
55 if (progress) {
56 nir_metadata_preserve(impl, nir_metadata_control_flow);
57 } else {
58 nir_metadata_preserve(impl, nir_metadata_all);
59 }
60
61 nir_instr_set_destroy(instr_set);
62 return progress;
63}
64
65bool
66nir_opt_cse(nir_shader *shader)
67{
68 bool progress = false;
69
70 nir_foreach_function_impl(impl, shader) {
71 progress |= nir_opt_cse_impl(impl);
72 }
73
74 return progress;
75}