1 /* Tree SCC value numbering
2 Copyright (C) 2007-2021 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, bool = true);
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. For internal
110 function calls clique is also used for the internal function code. */
111 unsigned short clique;
112 unsigned short base;
113 unsigned reverse : 1;
114 /* For storing TYPE_ALIGN for array ref element size computation. */
115 unsigned align : 6;
116 /* Constant offset this op adds or -1 if it is variable. */
117 poly_int64_pod off;
118 tree type;
119 tree op0;
120 tree op1;
121 tree op2;
122 } vn_reference_op_s;
123 typedef vn_reference_op_s *vn_reference_op_t;
124 typedef const vn_reference_op_s *const_vn_reference_op_t;
125
126 inline unsigned
vn_ref_op_align_unit(vn_reference_op_t op)127 vn_ref_op_align_unit (vn_reference_op_t op)
128 {
129 return op->align ? ((unsigned)1 << (op->align - 1)) / BITS_PER_UNIT : 0;
130 }
131
132 /* A reference operation in the hashtable is representation as
133 the vuse, representing the memory state at the time of
134 the operation, and a collection of operands that make up the
135 addressing calculation. If two vn_reference_t's have the same set
136 of operands, they access the same memory location. We also store
137 the resulting value number, and the hashcode. */
138
139 typedef struct vn_reference_s
140 {
141 vn_reference_s *next;
142 /* Unique identifier that all expressions with the same value have. */
143 unsigned int value_id;
144 hashval_t hashcode;
145 tree vuse;
146 alias_set_type set;
147 alias_set_type base_set;
148 tree type;
149 unsigned punned : 1;
150 vec<vn_reference_op_s> operands;
151 tree result;
152 tree result_vdef;
153 } *vn_reference_t;
154 typedef const struct vn_reference_s *const_vn_reference_t;
155
156 typedef struct vn_constant_s
157 {
158 unsigned int value_id;
159 hashval_t hashcode;
160 tree constant;
161 } *vn_constant_t;
162
163 enum vn_kind { VN_NONE, VN_CONSTANT, VN_NARY, VN_REFERENCE, VN_PHI };
164 enum vn_kind vn_get_stmt_kind (gimple *);
165
166 /* Hash the type TYPE using bits that distinguishes it in the
167 types_compatible_p sense. */
168
169 static inline hashval_t
vn_hash_type(tree type)170 vn_hash_type (tree type)
171 {
172 return (INTEGRAL_TYPE_P (type)
173 + (INTEGRAL_TYPE_P (type)
174 ? TYPE_PRECISION (type) + TYPE_UNSIGNED (type) : 0));
175 }
176
177 /* Hash the constant CONSTANT with distinguishing type incompatible
178 constants in the types_compatible_p sense. */
179
180 static inline hashval_t
vn_hash_constant_with_type(tree constant)181 vn_hash_constant_with_type (tree constant)
182 {
183 inchash::hash hstate;
184 inchash::add_expr (constant, hstate);
185 hstate.merge_hash (vn_hash_type (TREE_TYPE (constant)));
186 return hstate.end ();
187 }
188
189 /* Compare the constants C1 and C2 with distinguishing type incompatible
190 constants in the types_compatible_p sense. */
191
192 static inline bool
vn_constant_eq_with_type(tree c1,tree c2)193 vn_constant_eq_with_type (tree c1, tree c2)
194 {
195 return (expressions_equal_p (c1, c2)
196 && types_compatible_p (TREE_TYPE (c1), TREE_TYPE (c2)));
197 }
198
199 /* Instead of having a local availability lattice for each basic-block
200 and availability at X defined as union of the local availabilities
201 at X and its dominators we're turning this upside down and track
202 availability per value given values are usually made available at very
203 few points.
204 So we have a chain of LOCATION, LEADER entries where LOCATION is
205 specifying the basic-block LEADER is made available for VALUE.
206 We prepend to this chain in RPO order thus for iteration we can simply
207 remove the last entries.
208 LOCATION is the basic-block index and LEADER is its SSA name version. */
209 struct vn_avail
210 {
211 vn_avail *next;
212 /* The basic-block LEADER is made available. */
213 int location;
214 /* The LEADER for the value we are chained on. */
215 int leader;
216 /* The previous value we pushed a avail record to. */
217 struct vn_ssa_aux *next_undo;
218 };
219
220 typedef struct vn_ssa_aux
221 {
222 /* SSA name this vn_ssa_aux is associated with in the lattice. */
223 tree name;
224 /* Value number. This may be an SSA name or a constant. */
225 tree valnum;
226 /* Statements to insert if needs_insertion is true. */
227 gimple_seq expr;
228
229 /* AVAIL entries, last in RPO order is first. This is only tracked
230 for SSA names also serving as values (NAME == VALNUM). */
231 vn_avail *avail;
232
233 /* Unique identifier that all expressions with the same value have. */
234 unsigned int value_id;
235
236 /* Whether the SSA_NAME has been processed at least once. */
237 unsigned visited : 1;
238
239 /* Whether the SSA_NAME has no defining statement and thus an
240 insertion of such with EXPR as definition is required before
241 a use can be created of it. */
242 unsigned needs_insertion : 1;
243 } *vn_ssa_aux_t;
244
245 enum vn_lookup_kind { VN_NOWALK, VN_WALK, VN_WALKREWRITE };
246
247 /* Return the value numbering info for an SSA_NAME. */
248 bool has_VN_INFO (tree);
249 extern vn_ssa_aux_t VN_INFO (tree);
250 tree vn_get_expr_for (tree);
251 void scc_vn_restore_ssa_info (void);
252 tree vn_nary_op_lookup_stmt (gimple *, vn_nary_op_t *);
253 tree vn_nary_op_lookup_pieces (unsigned int, enum tree_code,
254 tree, tree *, vn_nary_op_t *);
255 vn_nary_op_t vn_nary_op_insert_pieces (unsigned int, enum tree_code,
256 tree, tree *, tree, unsigned int);
257 bool ao_ref_init_from_vn_reference (ao_ref *, alias_set_type, alias_set_type,
258 tree, const vec<vn_reference_op_s> &);
259 vec<vn_reference_op_s> vn_reference_operands_for_lookup (tree);
260 tree vn_reference_lookup_pieces (tree, alias_set_type, alias_set_type, tree,
261 vec<vn_reference_op_s> ,
262 vn_reference_t *, vn_lookup_kind);
263 tree vn_reference_lookup (tree, tree, vn_lookup_kind, vn_reference_t *, bool,
264 tree * = NULL, tree = NULL_TREE);
265 void vn_reference_lookup_call (gcall *, vn_reference_t *, vn_reference_t);
266 vn_reference_t vn_reference_insert_pieces (tree, alias_set_type, alias_set_type,
267 tree, vec<vn_reference_op_s>,
268 tree, unsigned int);
269 void print_vn_reference_ops (FILE *, const vec<vn_reference_op_s>);
270
271 bool vn_nary_op_eq (const_vn_nary_op_t const vno1,
272 const_vn_nary_op_t const vno2);
273 bool vn_nary_may_trap (vn_nary_op_t);
274 bool vn_reference_may_trap (vn_reference_t);
275 bool vn_reference_eq (const_vn_reference_t const, const_vn_reference_t const);
276
277 unsigned int get_max_value_id (void);
278 unsigned int get_max_constant_value_id (void);
279 unsigned int get_next_value_id (void);
280 unsigned int get_next_constant_value_id (void);
281 unsigned int get_constant_value_id (tree);
282 unsigned int get_or_alloc_constant_value_id (tree);
283
284 /* Return true if V is a value id for a constant. */
285 static inline bool
value_id_constant_p(unsigned int v)286 value_id_constant_p (unsigned int v)
287 {
288 return (int)v < 0;
289 }
290
291 tree fully_constant_vn_reference_p (vn_reference_t);
292 tree vn_nary_simplify (vn_nary_op_t);
293
294 unsigned do_rpo_vn (function *, edge, bitmap);
295 void run_rpo_vn (vn_lookup_kind);
296 unsigned eliminate_with_rpo_vn (bitmap);
297 void free_rpo_vn (void);
298
299 /* Valueize NAME if it is an SSA name, otherwise just return it. This hook
300 is initialized by run_scc_vn. */
301 extern tree (*vn_valueize) (tree);
302
303 /* Context that valueization should operate on. */
304 extern basic_block vn_context_bb;
305
306
307 #endif /* TREE_SSA_SCCVN_H */
308