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