1/* Header file for SSA jump threading.
2 Copyright (C) 2013-2025 Free Software Foundation, Inc.
3
4This file is part of GCC.
5
6GCC is free software; you can redistribute it and/or modify it under
7the terms of the GNU General Public License as published by the Free
8Software Foundation; either version 3, or (at your option) any later
9version.
10
11GCC is distributed in the hope that it will be useful, but WITHOUT ANY
12WARRANTY; without even the implied warranty of MERCHANTABILITY or
13FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 for more details.
15
16You should have received a copy of the GNU General Public License
17along with GCC; see the file COPYING3. If not see
18<http://www.gnu.org/licenses/>. */
19
20#ifndef GCC_TREE_SSA_THREADEDGE_H
21#define GCC_TREE_SSA_THREADEDGE_H
22
23// Class used to maintain path state in the jump threader and pass it
24// to the jump threader simplifier.
25
26class jt_state
27{
28public:
29 virtual ~jt_state () { }
30 virtual void push (edge);
31 virtual void pop ();
32 virtual void register_equiv (tree dest, tree src, bool update_range);
33 virtual void register_equivs_edge (edge e);
34 virtual void register_equivs_stmt (gimple *, basic_block,
35 class jt_simplifier *);
36 virtual void record_ranges_from_stmt (gimple *stmt, bool temporary);
37 void get_path (vec<basic_block> &);
38 void append_path (basic_block);
39 void dump (FILE *);
40 void debug ();
41
42private:
43 auto_vec<basic_block> m_blocks;
44 static const basic_block BB_MARKER;
45};
46
47// Statement simplifier callback for the jump threader.
48
49class jt_simplifier
50{
51public:
52 virtual ~jt_simplifier () { }
53 virtual tree simplify (gimple *, gimple *, basic_block, jt_state *) = 0;
54};
55
56class hybrid_jt_state : public jt_state
57{
58private:
59 void register_equivs_stmt (gimple *, basic_block, jt_simplifier *) override
60 {
61 // Ranger has no need to simplify anything.
62 }
63};
64
65class hybrid_jt_simplifier : public jt_simplifier
66{
67public:
68 hybrid_jt_simplifier (class gimple_ranger *r, class path_range_query *q);
69 tree simplify (gimple *stmt, gimple *, basic_block, jt_state *) override;
70
71private:
72 void compute_exit_dependencies (bitmap dependencies,
73 const vec<basic_block> &path,
74 gimple *stmt);
75
76 gimple_ranger *m_ranger;
77 path_range_query *m_query;
78};
79
80// This is the high level threader. The entry point is
81// thread_outgoing_edges(), which calculates and registers paths to be
82// threaded. When all candidates have been registered,
83// thread_through_all_blocks() is called to actually change the CFG.
84
85class jump_threader
86{
87public:
88 jump_threader (jt_simplifier *, class jt_state *);
89 ~jump_threader ();
90 void thread_outgoing_edges (basic_block);
91 void remove_jump_threads_including (edge_def *);
92 bool thread_through_all_blocks (bool may_peel_loop_headers);
93
94private:
95 tree simplify_control_stmt_condition (edge, gimple *);
96 tree simplify_control_stmt_condition_1 (edge,
97 gimple *,
98 tree op0,
99 tree_code cond_code,
100 tree op1,
101 unsigned limit);
102
103 bool thread_around_empty_blocks (vec<class jump_thread_edge *> *path,
104 edge, bitmap visited, unsigned &limit);
105 int thread_through_normal_block (vec<jump_thread_edge *> *path,
106 edge, bitmap visited, unsigned &limit);
107 void thread_across_edge (edge);
108 bool record_temporary_equivalences_from_phis (edge);
109 gimple *record_temporary_equivalences_from_stmts_at_dest (edge);
110
111 // Dummy condition to avoid creating lots of throw away statements.
112 gcond *dummy_cond;
113
114 class fwd_jt_path_registry *m_registry;
115 jt_simplifier *m_simplifier;
116 jt_state *m_state;
117};
118
119extern void propagate_threaded_block_debug_into (basic_block, basic_block);
120extern bool single_succ_to_potentially_threadable_block (basic_block);
121
122// ?? All this ssa_name_values stuff is the store of values for
123// avail_exprs_stack and const_and_copies, so it really belongs in the
124// jump_threader class. However, it's probably not worth touching
125// this, since all this windable state is slated to go with the
126// ranger.
127extern vec<tree> ssa_name_values;
128#define SSA_NAME_VALUE(x) \
129 (SSA_NAME_VERSION (x) < ssa_name_values.length () \
130 ? ssa_name_values[SSA_NAME_VERSION (x)] \
131 : NULL_TREE)
132extern void set_ssa_name_value (tree, tree);
133
134#endif /* GCC_TREE_SSA_THREADEDGE_H */
135

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source code of gcc/tree-ssa-threadedge.h