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 vec<vn_reference_op_s> operands;
149 tree result;
150 tree result_vdef;
151 } *vn_reference_t;
152 typedef const struct vn_reference_s *const_vn_reference_t;
153
154 typedef struct vn_constant_s
155 {
156 unsigned int value_id;
157 hashval_t hashcode;
158 tree constant;
159 } *vn_constant_t;
160
161 enum vn_kind { VN_NONE, VN_CONSTANT, VN_NARY, VN_REFERENCE, VN_PHI };
162 enum vn_kind vn_get_stmt_kind (gimple *);
163
164 /* Hash the type TYPE using bits that distinguishes it in the
165 types_compatible_p sense. */
166
167 static inline hashval_t
vn_hash_type(tree type)168 vn_hash_type (tree type)
169 {
170 return (INTEGRAL_TYPE_P (type)
171 + (INTEGRAL_TYPE_P (type)
172 ? TYPE_PRECISION (type) + TYPE_UNSIGNED (type) : 0));
173 }
174
175 /* Hash the constant CONSTANT with distinguishing type incompatible
176 constants in the types_compatible_p sense. */
177
178 static inline hashval_t
vn_hash_constant_with_type(tree constant)179 vn_hash_constant_with_type (tree constant)
180 {
181 inchash::hash hstate;
182 inchash::add_expr (constant, hstate);
183 hstate.merge_hash (vn_hash_type (TREE_TYPE (constant)));
184 return hstate.end ();
185 }
186
187 /* Compare the constants C1 and C2 with distinguishing type incompatible
188 constants in the types_compatible_p sense. */
189
190 static inline bool
vn_constant_eq_with_type(tree c1,tree c2)191 vn_constant_eq_with_type (tree c1, tree c2)
192 {
193 return (expressions_equal_p (c1, c2)
194 && types_compatible_p (TREE_TYPE (c1), TREE_TYPE (c2)));
195 }
196
197 /* Instead of having a local availability lattice for each basic-block
198 and availability at X defined as union of the local availabilities
199 at X and its dominators we're turning this upside down and track
200 availability per value given values are usually made available at very
201 few points.
202 So we have a chain of LOCATION, LEADER entries where LOCATION is
203 specifying the basic-block LEADER is made available for VALUE.
204 We prepend to this chain in RPO order thus for iteration we can simply
205 remove the last entries.
206 LOCATION is the basic-block index and LEADER is its SSA name version. */
207 struct vn_avail
208 {
209 vn_avail *next;
210 /* The basic-block LEADER is made available. */
211 int location;
212 /* The LEADER for the value we are chained on. */
213 int leader;
214 };
215
216 typedef struct vn_ssa_aux
217 {
218 /* SSA name this vn_ssa_aux is associated with in the lattice. */
219 tree name;
220 /* Value number. This may be an SSA name or a constant. */
221 tree valnum;
222 /* Statements to insert if needs_insertion is true. */
223 gimple_seq expr;
224
225 /* AVAIL entries, last in RPO order is first. This is only tracked
226 for SSA names also serving as values (NAME == VALNUM). */
227 vn_avail *avail;
228
229 /* Unique identifier that all expressions with the same value have. */
230 unsigned int value_id;
231
232 /* Whether the SSA_NAME has been processed at least once. */
233 unsigned visited : 1;
234
235 /* Whether the SSA_NAME has no defining statement and thus an
236 insertion of such with EXPR as definition is required before
237 a use can be created of it. */
238 unsigned needs_insertion : 1;
239 } *vn_ssa_aux_t;
240
241 enum vn_lookup_kind { VN_NOWALK, VN_WALK, VN_WALKREWRITE };
242
243 /* Return the value numbering info for an SSA_NAME. */
244 bool has_VN_INFO (tree);
245 extern vn_ssa_aux_t VN_INFO (tree);
246 tree vn_get_expr_for (tree);
247 void scc_vn_restore_ssa_info (void);
248 tree vn_nary_op_lookup_stmt (gimple *, vn_nary_op_t *);
249 tree vn_nary_op_lookup_pieces (unsigned int, enum tree_code,
250 tree, tree *, vn_nary_op_t *);
251 vn_nary_op_t vn_nary_op_insert_pieces (unsigned int, enum tree_code,
252 tree, tree *, tree, unsigned int);
253 bool ao_ref_init_from_vn_reference (ao_ref *, alias_set_type, alias_set_type,
254 tree, vec<vn_reference_op_s> );
255 vec<vn_reference_op_s> vn_reference_operands_for_lookup (tree);
256 tree vn_reference_lookup_pieces (tree, alias_set_type, alias_set_type, tree,
257 vec<vn_reference_op_s> ,
258 vn_reference_t *, vn_lookup_kind);
259 tree vn_reference_lookup (tree, tree, vn_lookup_kind, vn_reference_t *, bool,
260 tree * = NULL, tree = NULL_TREE);
261 void vn_reference_lookup_call (gcall *, vn_reference_t *, vn_reference_t);
262 vn_reference_t vn_reference_insert_pieces (tree, alias_set_type, alias_set_type,
263 tree, vec<vn_reference_op_s>,
264 tree, unsigned int);
265
266 bool vn_nary_op_eq (const_vn_nary_op_t const vno1,
267 const_vn_nary_op_t const vno2);
268 bool vn_nary_may_trap (vn_nary_op_t);
269 bool vn_reference_may_trap (vn_reference_t);
270 bool vn_reference_eq (const_vn_reference_t const, const_vn_reference_t const);
271 unsigned int get_max_value_id (void);
272 unsigned int get_next_value_id (void);
273 unsigned int get_constant_value_id (tree);
274 unsigned int get_or_alloc_constant_value_id (tree);
275 bool value_id_constant_p (unsigned int);
276 tree fully_constant_vn_reference_p (vn_reference_t);
277 tree vn_nary_simplify (vn_nary_op_t);
278
279 unsigned do_rpo_vn (function *, edge, bitmap);
280 void run_rpo_vn (vn_lookup_kind);
281 unsigned eliminate_with_rpo_vn (bitmap);
282 void free_rpo_vn (void);
283
284 /* Valueize NAME if it is an SSA name, otherwise just return it. This hook
285 is initialized by run_scc_vn. */
286 extern tree (*vn_valueize) (tree);
287
288 /* Context that valueization should operate on. */
289 extern basic_block vn_context_bb;
290
291
292 #endif /* TREE_SSA_SCCVN_H */
293