Line data Source code
1 : /* Communication between registering jump thread requests and
2 : updating the SSA/CFG for jump threading.
3 : Copyright (C) 2013-2026 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 28284218 : 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 : void remove_path (unsigned pathno);
75 : void remove_path (unsigned pathno, edge first);
76 : void add_first_edge (edge);
77 : void drop_first_edge (edge);
78 : unsigned first_edge_count (edge);
79 : vec<vec<jump_thread_edge *> *> m_paths;
80 : // How many registered paths start on a given edge.
81 : hash_map<edge, unsigned> m_first_edge_counts;
82 : unsigned long m_num_threaded_edges;
83 : private:
84 : virtual bool update_cfg (bool peel_loop_headers) = 0;
85 : bool cancel_invalid_paths (vec<jump_thread_edge *> &path);
86 : jump_thread_path_allocator m_allocator;
87 : // True if threading through back edges is allowed. This is only
88 : // allowed in the generic copier in the backward threader.
89 : bool m_backedge_threads;
90 : DISABLE_COPY_AND_ASSIGN (jt_path_registry);
91 : };
92 :
93 : // Forward threader path registry using a custom BB copier.
94 :
95 : class fwd_jt_path_registry : public jt_path_registry
96 : {
97 : public:
98 : fwd_jt_path_registry ();
99 : ~fwd_jt_path_registry ();
100 : void remove_jump_threads_including (edge);
101 : private:
102 : bool update_cfg (bool peel_loop_headers) override;
103 : void mark_threaded_blocks (bitmap threaded_blocks);
104 : bool thread_block_1 (basic_block, bool noloop_only, bool joiners);
105 : bool thread_block (basic_block, bool noloop_only);
106 : bool thread_through_loop_header (class loop *loop,
107 : bool may_peel_loop_headers);
108 : class redirection_data *lookup_redirection_data (edge e, enum insert_option);
109 :
110 : hash_table<struct removed_edges> *m_removed_edges;
111 :
112 : // Main data structure to hold information for duplicates of BB.
113 : hash_table<redirection_data> *m_redirection_data;
114 : };
115 :
116 : // Backward threader path registry using a generic BB copier.
117 :
118 6477228 : class back_jt_path_registry : public jt_path_registry
119 : {
120 : public:
121 : back_jt_path_registry ();
122 : private:
123 : bool update_cfg (bool peel_loop_headers) override;
124 : void adjust_paths_after_duplication (unsigned curr_path_num);
125 : bool duplicate_thread_path (edge entry, edge exit, basic_block *region,
126 : unsigned n_region, unsigned current_path_no,
127 : const char **failure_reason);
128 : bool rewire_first_differing_edge (unsigned path_num, unsigned edge_num);
129 : bool adjust_one_path (vec<jump_thread_edge *> *curr_path,
130 : unsigned cand_path_num);
131 : };
132 :
133 : // Rather than search all the edges in jump thread paths each time DOM
134 : // is able to simply if control statement, we build a hash table with
135 : // the deleted edges. We only care about the address of the edge, not
136 : // its contents.
137 : struct removed_edges : nofree_ptr_hash<edge_def>
138 : {
139 5493981 : static hashval_t hash (edge e) { return htab_hash_pointer (e); }
140 : static bool equal (edge e1, edge e2) { return e1 == e2; }
141 : };
142 :
143 : extern unsigned int estimate_threading_killed_stmts (basic_block);
144 :
145 : enum bb_dom_status
146 : {
147 : /* BB does not dominate latch of the LOOP. */
148 : DOMST_NONDOMINATING,
149 : /* The LOOP is broken (there is no path from the header to its latch. */
150 : DOMST_LOOP_BROKEN,
151 : /* BB dominates the latch of the LOOP. */
152 : DOMST_DOMINATING
153 : };
154 :
155 : enum bb_dom_status determine_bb_domination_status (class loop *, basic_block);
156 :
157 : // In tree-ssa-dom.cc.
158 : extern void free_dom_edge_info (edge);
159 :
160 : #endif
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