1 /*
2 * Copyright © 2016 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 #ifndef NIR_LOOP_ANALYZE_H
25 #define NIR_LOOP_ANALYZE_H
26
27 #include "nir.h"
28
29 /* Returns true if nir_cf_node contains a jump other than the expected_jump
30 * parameter.
31 */
32 static inline bool
contains_other_jump(nir_cf_node * node,nir_instr * expected_jump)33 contains_other_jump(nir_cf_node *node, nir_instr *expected_jump)
34 {
35 switch (node->type) {
36 case nir_cf_node_block: {
37 nir_instr *lst_instr = nir_block_last_instr(nir_cf_node_as_block(node));
38
39 /* dead_cf should have eliminated any instruction after the first break
40 */
41 nir_foreach_instr(instr, nir_cf_node_as_block(node))
42 assert(instr->type != nir_instr_type_jump || instr == lst_instr);
43
44 if (lst_instr && lst_instr->type == nir_instr_type_jump &&
45 lst_instr != expected_jump)
46 return true;
47 else
48 return false;
49 }
50 case nir_cf_node_if: {
51 nir_if *if_stmt = nir_cf_node_as_if(node);
52
53 foreach_list_typed_safe(nir_cf_node, node, node, &if_stmt->then_list) {
54 if (contains_other_jump(node, expected_jump))
55 return true;
56 }
57
58 foreach_list_typed_safe(nir_cf_node, node, node, &if_stmt->else_list) {
59 if (contains_other_jump(node, expected_jump))
60 return true;
61 }
62
63 return false;
64 }
65 case nir_cf_node_loop:
66 return true;
67
68 default:
69 unreachable("Unhandled cf node type");
70 }
71 }
72
73 /* Here we define a trivial if as containing only a single break that must be
74 * located at the end of either the then or else branch of the top level if,
75 * there must be no other breaks or any other type of jump. Or we pass NULL
76 * to break_block the if must contains no jumps at all.
77 */
78 static inline bool
nir_is_trivial_loop_if(nir_if * nif,nir_block * break_block)79 nir_is_trivial_loop_if(nir_if *nif, nir_block *break_block)
80 {
81 nir_instr *last_instr = NULL;
82
83 if (break_block) {
84 last_instr = nir_block_last_instr(break_block);
85 assert(last_instr && last_instr->type == nir_instr_type_jump &&
86 nir_instr_as_jump(last_instr)->type == nir_jump_break);
87 }
88
89 if (contains_other_jump(&nif->cf_node, last_instr))
90 return false;
91
92 return true;
93 }
94
95 static inline bool
nir_block_ends_in_break(nir_block * block)96 nir_block_ends_in_break(nir_block *block)
97 {
98 if (exec_list_is_empty(&block->instr_list))
99 return false;
100
101 nir_instr *instr = nir_block_last_instr(block);
102 return instr->type == nir_instr_type_jump &&
103 nir_instr_as_jump(instr)->type == nir_jump_break;
104 }
105
106 #endif /* NIR_LOOP_ANALYZE_H */
107