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1 : : /* Communication between registering jump thread requests and
2 : : updating the SSA/CFG for jump threading.
3 : : Copyright (C) 2013-2024 Free Software Foundation, Inc.
4 : :
5 : : This file is part of GCC.
6 : :
7 : : GCC is free software; you can redistribute it and/or modify
8 : : it under the terms of the GNU General Public License as published by
9 : : the Free Software Foundation; either version 3, or (at your option)
10 : : any later version.
11 : :
12 : : GCC is distributed in the hope that it will be useful,
13 : : but WITHOUT ANY WARRANTY; without even the implied warranty of
14 : : MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 : : GNU General Public License for more details.
16 : :
17 : : You should have received a copy of the GNU General Public License
18 : : along with GCC; see the file COPYING3. If not see
19 : : <http://www.gnu.org/licenses/>. */
20 : :
21 : : #ifndef _TREE_SSA_THREADUPDATE_H
22 : : #define _TREE_SSA_THREADUPDATE_H 1
23 : :
24 : : enum jump_thread_edge_type
25 : : {
26 : : EDGE_START_JUMP_THREAD,
27 : : EDGE_COPY_SRC_BLOCK,
28 : : EDGE_COPY_SRC_JOINER_BLOCK,
29 : : EDGE_NO_COPY_SRC_BLOCK
30 : : };
31 : :
32 : : // We keep the registered jump threading opportunities in this
33 : : // vector as edge pairs (original_edge, target_edge).
34 : :
35 : : class jump_thread_edge
36 : : {
37 : : public:
38 : 22049700 : jump_thread_edge (edge e, jump_thread_edge_type t) : e (e), type (t) {}
39 : :
40 : : edge e;
41 : : jump_thread_edge_type type;
42 : : };
43 : :
44 : : class jump_thread_path_allocator
45 : : {
46 : : public:
47 : : jump_thread_path_allocator ();
48 : : ~jump_thread_path_allocator ();
49 : : jump_thread_edge *allocate_thread_edge (edge, jump_thread_edge_type);
50 : : vec<jump_thread_edge *> *allocate_thread_path ();
51 : : private:
52 : : DISABLE_COPY_AND_ASSIGN (jump_thread_path_allocator);
53 : : obstack m_obstack;
54 : : };
55 : :
56 : : // Abstract class for the jump thread registry.
57 : : //
58 : : // When all candidates have been registered with
59 : : // register_jump_thread(), thread_through_all_blocks() is called to
60 : : // update the CFG.
61 : :
62 : : class jt_path_registry
63 : : {
64 : : public:
65 : : jt_path_registry (bool backedge_threads);
66 : : virtual ~jt_path_registry ();
67 : : bool register_jump_thread (vec<jump_thread_edge *> *);
68 : : bool thread_through_all_blocks (bool peel_loop_headers);
69 : : void push_edge (vec<jump_thread_edge *> *path, edge, jump_thread_edge_type);
70 : : vec<jump_thread_edge *> *allocate_thread_path ();
71 : : void debug ();
72 : : protected:
73 : : void debug_path (FILE *, int pathno);
74 : : vec<vec<jump_thread_edge *> *> m_paths;
75 : : unsigned long m_num_threaded_edges;
76 : : private:
77 : : virtual bool update_cfg (bool peel_loop_headers) = 0;
78 : : bool cancel_invalid_paths (vec<jump_thread_edge *> &path);
79 : : jump_thread_path_allocator m_allocator;
80 : : // True if threading through back edges is allowed. This is only
81 : : // allowed in the generic copier in the backward threader.
82 : : bool m_backedge_threads;
83 : : DISABLE_COPY_AND_ASSIGN (jt_path_registry);
84 : : };
85 : :
86 : : // Forward threader path registry using a custom BB copier.
87 : :
88 : : class fwd_jt_path_registry : public jt_path_registry
89 : : {
90 : : public:
91 : : fwd_jt_path_registry ();
92 : : ~fwd_jt_path_registry ();
93 : : void remove_jump_threads_including (edge);
94 : : private:
95 : : bool update_cfg (bool peel_loop_headers) override;
96 : : void mark_threaded_blocks (bitmap threaded_blocks);
97 : : bool thread_block_1 (basic_block, bool noloop_only, bool joiners);
98 : : bool thread_block (basic_block, bool noloop_only);
99 : : bool thread_through_loop_header (class loop *loop,
100 : : bool may_peel_loop_headers);
101 : : class redirection_data *lookup_redirection_data (edge e, enum insert_option);
102 : :
103 : : hash_table<struct removed_edges> *m_removed_edges;
104 : :
105 : : // Main data structure to hold information for duplicates of BB.
106 : : hash_table<redirection_data> *m_redirection_data;
107 : : };
108 : :
109 : : // Backward threader path registry using a generic BB copier.
110 : :
111 : 5883225 : class back_jt_path_registry : public jt_path_registry
112 : : {
113 : : public:
114 : : back_jt_path_registry ();
115 : : private:
116 : : bool update_cfg (bool peel_loop_headers) override;
117 : : void adjust_paths_after_duplication (unsigned curr_path_num);
118 : : bool duplicate_thread_path (edge entry, edge exit, basic_block *region,
119 : : unsigned n_region, unsigned current_path_no);
120 : : bool rewire_first_differing_edge (unsigned path_num, unsigned edge_num);
121 : : };
122 : :
123 : : // Rather than search all the edges in jump thread paths each time DOM
124 : : // is able to simply if control statement, we build a hash table with
125 : : // the deleted edges. We only care about the address of the edge, not
126 : : // its contents.
127 : : struct removed_edges : nofree_ptr_hash<edge_def>
128 : : {
129 : 2823849 : static hashval_t hash (edge e) { return htab_hash_pointer (e); }
130 : : static bool equal (edge e1, edge e2) { return e1 == e2; }
131 : : };
132 : :
133 : : extern unsigned int estimate_threading_killed_stmts (basic_block);
134 : :
135 : : enum bb_dom_status
136 : : {
137 : : /* BB does not dominate latch of the LOOP. */
138 : : DOMST_NONDOMINATING,
139 : : /* The LOOP is broken (there is no path from the header to its latch. */
140 : : DOMST_LOOP_BROKEN,
141 : : /* BB dominates the latch of the LOOP. */
142 : : DOMST_DOMINATING
143 : : };
144 : :
145 : : enum bb_dom_status determine_bb_domination_status (class loop *, basic_block);
146 : :
147 : : // In tree-ssa-dom.cc.
148 : : extern void free_dom_edge_info (edge);
149 : :
150 : : #endif
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