1 /* Tree SCC value numbering
2 Copyright (C) 2007-2020 Free Software Foundation, Inc.
3 Contributed by Daniel Berlin <dberlin@dberlin.org>
4
5 This file is part of GCC.
6
7 GCC is free software; you can redistribute it and/or modify
8 under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 3 of the License, or
10 (at your option) 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_SCCVN_H
22 #define TREE_SSA_SCCVN_H
23
24 /* In tree-ssa-sccvn.c */
25 bool expressions_equal_p (tree, tree);
26
27
28 /* TOP of the VN lattice. */
29 extern tree VN_TOP;
30
31 /* A predicated value. */
32 struct vn_pval
33 {
34 vn_pval *next;
35 /* The value of the expression this is attached to is RESULT in
36 case the expression is computed dominated by one of the blocks
37 in valid_dominated_by_p. */
38 tree result;
39 unsigned n;
40 int valid_dominated_by_p[1];
41 };
42
43 /* N-ary operations in the hashtable consist of length operands, an
44 opcode, and a type. Result is the value number of the operation,
45 and hashcode is stored to avoid having to calculate it
46 repeatedly. */
47
48 typedef struct vn_nary_op_s
49 {
50 vn_nary_op_s *next;
51 vn_nary_op_s *unwind_to;
52 /* Unique identify that all expressions with the same value have. */
53 unsigned int value_id;
54 ENUM_BITFIELD(tree_code) opcode : 16;
55 unsigned length : 16;
56 hashval_t hashcode;
57 unsigned predicated_values : 1;
58 union {
59 /* If ! predicated_values this is the value of the expression. */
60 tree result;
61 /* If predicated_values this is a list of values of the expression. */
62 vn_pval *values;
63 } u;
64 tree type;
65 tree op[1];
66 } *vn_nary_op_t;
67 typedef const struct vn_nary_op_s *const_vn_nary_op_t;
68
69 /* Return the size of a vn_nary_op_t with LENGTH operands. */
70
71 static inline size_t
sizeof_vn_nary_op(unsigned int length)72 sizeof_vn_nary_op (unsigned int length)
73 {
74 return sizeof (struct vn_nary_op_s) + sizeof (tree) * length - sizeof (tree);
75 }
76
77 /* Phi nodes in the hashtable consist of their non-VN_TOP phi
78 arguments, and the basic block the phi is in. Result is the value
79 number of the operation, and hashcode is stored to avoid having to
80 calculate it repeatedly. Phi nodes not in the same block are never
81 considered equivalent. */
82
83 typedef struct vn_phi_s
84 {
85 vn_phi_s *next;
86 /* Unique identifier that all expressions with the same value have. */
87 unsigned int value_id;
88 hashval_t hashcode;
89 basic_block block;
90 /* Controlling condition lhs/rhs. */
91 tree cclhs;
92 tree ccrhs;
93 tree type;
94 tree result;
95 /* The number of args is determined by EDGE_COUT (block->preds). */
96 tree phiargs[1];
97 } *vn_phi_t;
98 typedef const struct vn_phi_s *const_vn_phi_t;
99
100 /* Reference operands only exist in reference operations structures.
101 They consist of an opcode, type, and some number of operands. For
102 a given opcode, some, all, or none of the operands may be used.
103 The operands are there to store the information that makes up the
104 portion of the addressing calculation that opcode performs. */
105
106 typedef struct vn_reference_op_struct
107 {
108 ENUM_BITFIELD(tree_code) opcode : 16;
109 /* Dependence info, used for [TARGET_]MEM_REF only. */
110 unsigned short clique;
111 unsigned short base;
112 unsigned reverse : 1;
113 /* For storing TYPE_ALIGN for array ref element size computation. */
114 unsigned align : 6;
115 /* Constant offset this op adds or -1 if it is variable. */
116 poly_int64_pod off;
117 tree type;
118 tree op0;
119 tree op1;
120 tree op2;
121 } vn_reference_op_s;
122 typedef vn_reference_op_s *vn_reference_op_t;
123 typedef const vn_reference_op_s *const_vn_reference_op_t;
124
125 inline unsigned
vn_ref_op_align_unit(vn_reference_op_t op)126 vn_ref_op_align_unit (vn_reference_op_t op)
127 {
128 return op->align ? ((unsigned)1 << (op->align - 1)) / BITS_PER_UNIT : 0;
129 }
130
131 /* A reference operation in the hashtable is representation as
132 the vuse, representing the memory state at the time of
133 the operation, and a collection of operands that make up the
134 addressing calculation. If two vn_reference_t's have the same set
135 of operands, they access the same memory location. We also store
136 the resulting value number, and the hashcode. */
137
138 typedef struct vn_reference_s
139 {
140 vn_reference_s *next;
141 /* Unique identifier that all expressions with the same value have. */
142 unsigned int value_id;
143 hashval_t hashcode;
144 tree vuse;
145 alias_set_type set;
146 alias_set_type base_set;
147 tree type;
148 unsigned punned : 1;
149 vec<vn_reference_op_s> operands;
150 tree result;
151 tree result_vdef;
152 } *vn_reference_t;
153 typedef const struct vn_reference_s *const_vn_reference_t;
154
155 typedef struct vn_constant_s
156 {
157 unsigned int value_id;
158 hashval_t hashcode;
159 tree constant;
160 } *vn_constant_t;
161
162 enum vn_kind { VN_NONE, VN_CONSTANT, VN_NARY, VN_REFERENCE, VN_PHI };
163 enum vn_kind vn_get_stmt_kind (gimple *);
164
165 /* Hash the type TYPE using bits that distinguishes it in the
166 types_compatible_p sense. */
167
168 static inline hashval_t
vn_hash_type(tree type)169 vn_hash_type (tree type)
170 {
171 return (INTEGRAL_TYPE_P (type)
172 + (INTEGRAL_TYPE_P (type)
173 ? TYPE_PRECISION (type) + TYPE_UNSIGNED (type) : 0));
174 }
175
176 /* Hash the constant CONSTANT with distinguishing type incompatible
177 constants in the types_compatible_p sense. */
178
179 static inline hashval_t
vn_hash_constant_with_type(tree constant)180 vn_hash_constant_with_type (tree constant)
181 {
182 inchash::hash hstate;
183 inchash::add_expr (constant, hstate);
184 hstate.merge_hash (vn_hash_type (TREE_TYPE (constant)));
185 return hstate.end ();
186 }
187
188 /* Compare the constants C1 and C2 with distinguishing type incompatible
189 constants in the types_compatible_p sense. */
190
191 static inline bool
vn_constant_eq_with_type(tree c1,tree c2)192 vn_constant_eq_with_type (tree c1, tree c2)
193 {
194 return (expressions_equal_p (c1, c2)
195 && types_compatible_p (TREE_TYPE (c1), TREE_TYPE (c2)));
196 }
197
198 /* Instead of having a local availability lattice for each basic-block
199 and availability at X defined as union of the local availabilities
200 at X and its dominators we're turning this upside down and track
201 availability per value given values are usually made available at very
202 few points.
203 So we have a chain of LOCATION, LEADER entries where LOCATION is
204 specifying the basic-block LEADER is made available for VALUE.
205 We prepend to this chain in RPO order thus for iteration we can simply
206 remove the last entries.
207 LOCATION is the basic-block index and LEADER is its SSA name version. */
208 struct vn_avail
209 {
210 vn_avail *next;
211 /* The basic-block LEADER is made available. */
212 int location;
213 /* The LEADER for the value we are chained on. */
214 int leader;
215 };
216
217 typedef struct vn_ssa_aux
218 {
219 /* SSA name this vn_ssa_aux is associated with in the lattice. */
220 tree name;
221 /* Value number. This may be an SSA name or a constant. */
222 tree valnum;
223 /* Statements to insert if needs_insertion is true. */
224 gimple_seq expr;
225
226 /* AVAIL entries, last in RPO order is first. This is only tracked
227 for SSA names also serving as values (NAME == VALNUM). */
228 vn_avail *avail;
229
230 /* Unique identifier that all expressions with the same value have. */
231 unsigned int value_id;
232
233 /* Whether the SSA_NAME has been processed at least once. */
234 unsigned visited : 1;
235
236 /* Whether the SSA_NAME has no defining statement and thus an
237 insertion of such with EXPR as definition is required before
238 a use can be created of it. */
239 unsigned needs_insertion : 1;
240 } *vn_ssa_aux_t;
241
242 enum vn_lookup_kind { VN_NOWALK, VN_WALK, VN_WALKREWRITE };
243
244 /* Return the value numbering info for an SSA_NAME. */
245 bool has_VN_INFO (tree);
246 extern vn_ssa_aux_t VN_INFO (tree);
247 tree vn_get_expr_for (tree);
248 void scc_vn_restore_ssa_info (void);
249 tree vn_nary_op_lookup_stmt (gimple *, vn_nary_op_t *);
250 tree vn_nary_op_lookup_pieces (unsigned int, enum tree_code,
251 tree, tree *, vn_nary_op_t *);
252 vn_nary_op_t vn_nary_op_insert_pieces (unsigned int, enum tree_code,
253 tree, tree *, tree, unsigned int);
254 bool ao_ref_init_from_vn_reference (ao_ref *, alias_set_type, alias_set_type,
255 tree, vec<vn_reference_op_s> );
256 vec<vn_reference_op_s> vn_reference_operands_for_lookup (tree);
257 tree vn_reference_lookup_pieces (tree, alias_set_type, alias_set_type, tree,
258 vec<vn_reference_op_s> ,
259 vn_reference_t *, vn_lookup_kind);
260 tree vn_reference_lookup (tree, tree, vn_lookup_kind, vn_reference_t *, bool,
261 tree * = NULL, tree = NULL_TREE);
262 void vn_reference_lookup_call (gcall *, vn_reference_t *, vn_reference_t);
263 vn_reference_t vn_reference_insert_pieces (tree, alias_set_type, alias_set_type,
264 tree, vec<vn_reference_op_s>,
265 tree, unsigned int);
266
267 bool vn_nary_op_eq (const_vn_nary_op_t const vno1,
268 const_vn_nary_op_t const vno2);
269 bool vn_nary_may_trap (vn_nary_op_t);
270 bool vn_reference_may_trap (vn_reference_t);
271 bool vn_reference_eq (const_vn_reference_t const, const_vn_reference_t const);
272 unsigned int get_max_value_id (void);
273 unsigned int get_next_value_id (void);
274 unsigned int get_constant_value_id (tree);
275 unsigned int get_or_alloc_constant_value_id (tree);
276 bool value_id_constant_p (unsigned int);
277 tree fully_constant_vn_reference_p (vn_reference_t);
278 tree vn_nary_simplify (vn_nary_op_t);
279
280 unsigned do_rpo_vn (function *, edge, bitmap);
281 void run_rpo_vn (vn_lookup_kind);
282 unsigned eliminate_with_rpo_vn (bitmap);
283 void free_rpo_vn (void);
284
285 /* Valueize NAME if it is an SSA name, otherwise just return it. This hook
286 is initialized by run_scc_vn. */
287 extern tree (*vn_valueize) (tree);
288
289 /* Context that valueization should operate on. */
290 extern basic_block vn_context_bb;
291
292
293 #endif /* TREE_SSA_SCCVN_H */
294