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 25495055 : 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 6268414 : 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 5311101 : 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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