1 | /* Header file for SSA dominator optimizations. |
2 | Copyright (C) 2013-2023 Free Software Foundation, Inc. |
3 | |
4 | This file is part of GCC. |
5 | |
6 | GCC is free software; you can redistribute it and/or modify it under |
7 | the terms of the GNU General Public License as published by the Free |
8 | Software Foundation; either version 3, or (at your option) any later |
9 | version. |
10 | |
11 | GCC is distributed in the hope that it will be useful, but WITHOUT ANY |
12 | WARRANTY; without even the implied warranty of MERCHANTABILITY or |
13 | FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
14 | for more details. |
15 | |
16 | You should have received a copy of the GNU General Public License |
17 | along with GCC; see the file COPYING3. If not see |
18 | <http://www.gnu.org/licenses/>. */ |
19 | |
20 | #ifndef GCC_TREE_SSA_SCOPED_TABLES_H |
21 | #define GCC_TREE_SSA_SCOPED_TABLES_H |
22 | |
23 | /* Representation of a "naked" right-hand-side expression, to be used |
24 | in recording available expressions in the expression hash table. */ |
25 | |
26 | enum expr_kind |
27 | { |
28 | EXPR_SINGLE, |
29 | EXPR_UNARY, |
30 | EXPR_BINARY, |
31 | EXPR_TERNARY, |
32 | EXPR_CALL, |
33 | EXPR_PHI |
34 | }; |
35 | |
36 | struct hashable_expr |
37 | { |
38 | tree type; |
39 | enum expr_kind kind; |
40 | union { |
41 | struct { tree rhs; } single; |
42 | struct { enum tree_code op; tree opnd; } unary; |
43 | struct { enum tree_code op; tree opnd0, opnd1; } binary; |
44 | struct { enum tree_code op; tree opnd0, opnd1, opnd2; } ternary; |
45 | struct { gcall *fn_from; bool pure; size_t nargs; tree *args; } call; |
46 | struct { size_t nargs; tree *args; } phi; |
47 | } ops; |
48 | }; |
49 | |
50 | /* Structure for recording known value of a conditional expression. |
51 | |
52 | Clients build vectors of these objects to record known values |
53 | that occur on edges. */ |
54 | |
55 | struct cond_equivalence |
56 | { |
57 | /* The condition, in a HASHABLE_EXPR form. */ |
58 | struct hashable_expr cond; |
59 | |
60 | /* The result of the condition (true or false. */ |
61 | tree value; |
62 | }; |
63 | |
64 | /* Structure for entries in the expression hash table. */ |
65 | |
66 | typedef class expr_hash_elt * expr_hash_elt_t; |
67 | |
68 | class expr_hash_elt |
69 | { |
70 | public: |
71 | expr_hash_elt (gimple *, tree); |
72 | expr_hash_elt (tree); |
73 | expr_hash_elt (struct hashable_expr *, tree); |
74 | expr_hash_elt (class expr_hash_elt &); |
75 | ~expr_hash_elt (); |
76 | void print (FILE *); |
77 | tree vop (void) { return m_vop; } |
78 | tree lhs (void) { return m_lhs; } |
79 | struct hashable_expr *expr (void) { return &m_expr; } |
80 | expr_hash_elt *stamp (void) { return m_stamp; } |
81 | hashval_t hash (void) { return m_hash; } |
82 | |
83 | private: |
84 | /* The expression (rhs) we want to record. */ |
85 | struct hashable_expr m_expr; |
86 | |
87 | /* The value (lhs) of this expression. */ |
88 | tree m_lhs; |
89 | |
90 | /* The virtual operand associated with the nearest dominating stmt |
91 | loading from or storing to expr. */ |
92 | tree m_vop; |
93 | |
94 | /* The hash value for RHS. */ |
95 | hashval_t m_hash; |
96 | |
97 | /* A unique stamp, typically the address of the hash |
98 | element itself, used in removing entries from the table. */ |
99 | class expr_hash_elt *m_stamp; |
100 | |
101 | /* We should never be making assignments between objects in this class. |
102 | Though it might allow us to exploit C++11 move semantics if we |
103 | defined the move constructor and move assignment operator. */ |
104 | expr_hash_elt& operator= (const expr_hash_elt&); |
105 | }; |
106 | |
107 | /* Hashtable helpers. */ |
108 | |
109 | struct expr_elt_hasher : pointer_hash <expr_hash_elt> |
110 | { |
111 | static inline hashval_t hash (const value_type &p) |
112 | { return p->hash (); } |
113 | static bool equal (const value_type &, const compare_type &); |
114 | static inline void remove (value_type &element) |
115 | { delete element; } |
116 | }; |
117 | |
118 | |
119 | /* This class defines a unwindable expression equivalence table |
120 | layered on top of the expression hash table. |
121 | |
122 | Essentially it's just a stack of available expression value pairs with |
123 | a special marker (NULL, NULL) to indicate unwind points. */ |
124 | |
125 | class avail_exprs_stack |
126 | { |
127 | public: |
128 | /* We need access to the AVAIL_EXPR hash table so that we can |
129 | remove entries from the hash table when unwinding the stack. */ |
130 | avail_exprs_stack (hash_table<expr_elt_hasher> *table) |
131 | { m_stack.create (nelems: 20); m_avail_exprs = table; } |
132 | ~avail_exprs_stack (void) { m_stack.release (); } |
133 | |
134 | /* Push the unwinding marker onto the stack. */ |
135 | void push_marker (void) { record_expr (NULL, NULL, 'M'); } |
136 | |
137 | /* Restore the AVAIL_EXPRs table to its state when the last marker |
138 | was pushed. */ |
139 | void pop_to_marker (void); |
140 | |
141 | /* Record a single available expression that can be unwound. */ |
142 | void record_expr (expr_hash_elt_t, expr_hash_elt_t, char); |
143 | |
144 | /* Get the underlying hash table. Would this be better as |
145 | class inheritance? */ |
146 | hash_table<expr_elt_hasher> *avail_exprs (void) |
147 | { return m_avail_exprs; } |
148 | |
149 | /* Lookup and conditionally insert an expression into the table, |
150 | recording enough information to unwind as needed. */ |
151 | tree lookup_avail_expr (gimple *, bool, bool, expr_hash_elt ** = NULL); |
152 | |
153 | void record_cond (cond_equivalence *); |
154 | |
155 | private: |
156 | vec<std::pair<expr_hash_elt_t, expr_hash_elt_t> > m_stack; |
157 | hash_table<expr_elt_hasher> *m_avail_exprs; |
158 | |
159 | /* For some assignments where the RHS is a binary operator, if we know |
160 | a equality relationship between the operands, we may be able to compute |
161 | a result, even if we don't know the exact value of the operands. */ |
162 | tree simplify_binary_operation (gimple *, class expr_hash_elt); |
163 | |
164 | /* We do not allow copying this object or initializing one |
165 | from another. */ |
166 | avail_exprs_stack& operator= (const avail_exprs_stack&); |
167 | avail_exprs_stack (class avail_exprs_stack &); |
168 | }; |
169 | |
170 | /* This class defines an unwindable const/copy equivalence table |
171 | layered on top of SSA_NAME_VALUE/set_ssa_name_value. |
172 | |
173 | Essentially it's just a stack of name,prev value pairs with a |
174 | special marker (NULL) to indicate unwind points. */ |
175 | |
176 | class const_and_copies |
177 | { |
178 | public: |
179 | const_and_copies (void) { m_stack.create (nelems: 20); }; |
180 | ~const_and_copies (void) { m_stack.release (); } |
181 | |
182 | /* Push the unwinding marker onto the stack. */ |
183 | void push_marker (void) { m_stack.safe_push (NULL_TREE); } |
184 | |
185 | /* Restore the const/copies table to its state when the last marker |
186 | was pushed. */ |
187 | void pop_to_marker (void); |
188 | |
189 | /* Record a single const/copy pair that can be unwound. This version |
190 | may follow the value chain for the RHS. */ |
191 | void record_const_or_copy (tree, tree); |
192 | |
193 | /* Special entry point when we want to provide an explicit previous |
194 | value for the first argument. Try to get rid of this in the future. |
195 | |
196 | This version may also follow the value chain for the RHS. */ |
197 | void record_const_or_copy (tree, tree, tree); |
198 | |
199 | private: |
200 | /* Record a single const/copy pair that can be unwound. This version |
201 | does not follow the value chain for the RHS. */ |
202 | void record_const_or_copy_raw (tree, tree, tree); |
203 | |
204 | vec<tree> m_stack; |
205 | const_and_copies& operator= (const const_and_copies&); |
206 | const_and_copies (class const_and_copies &); |
207 | }; |
208 | |
209 | void initialize_expr_from_cond (tree cond, struct hashable_expr *expr); |
210 | void record_conditions (vec<cond_equivalence> *p, tree, tree); |
211 | |
212 | #endif /* GCC_TREE_SSA_SCOPED_TABLES_H */ |
213 | |