nir_loop_analyze.h revision b8e80941 
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 */
32static inline bool
33contains_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 */
78static inline bool
79nir_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
95static inline bool
96nir_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