GCC Middle and Back End API Reference
tree-ssa-sccvn.h
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1 /* Tree SCC value numbering
2  Copyright (C) 2007-2013 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 /* N-ary operations in the hashtable consist of length operands, an
32  opcode, and a type. Result is the value number of the operation,
33  and hashcode is stored to avoid having to calculate it
34  repeatedly. */
35 
36 typedef struct vn_nary_op_s
37 {
38  /* Unique identify that all expressions with the same value have. */
39  unsigned int value_id;
40  ENUM_BITFIELD(tree_code) opcode : 16;
41  unsigned length : 16;
42  hashval_t hashcode;
43  tree result;
44  tree type;
45  tree op[1];
46 } *vn_nary_op_t;
47 typedef const struct vn_nary_op_s *const_vn_nary_op_t;
48 
49 /* Return the size of a vn_nary_op_t with LENGTH operands. */
50 
51 static inline size_t
52 sizeof_vn_nary_op (unsigned int length)
53 {
54  return sizeof (struct vn_nary_op_s) + sizeof (tree) * length - sizeof (tree);
55 }
56 
57 /* Phi nodes in the hashtable consist of their non-VN_TOP phi
58  arguments, and the basic block the phi is in. Result is the value
59  number of the operation, and hashcode is stored to avoid having to
60  calculate it repeatedly. Phi nodes not in the same block are never
61  considered equivalent. */
62 
63 typedef struct vn_phi_s
64 {
65  /* Unique identifier that all expressions with the same value have. */
66  unsigned int value_id;
67  hashval_t hashcode;
68  vec<tree> phiargs;
69  basic_block block;
70  tree type;
71  tree result;
72 } *vn_phi_t;
73 typedef const struct vn_phi_s *const_vn_phi_t;
74 
75 /* Reference operands only exist in reference operations structures.
76  They consist of an opcode, type, and some number of operands. For
77  a given opcode, some, all, or none of the operands may be used.
78  The operands are there to store the information that makes up the
79  portion of the addressing calculation that opcode performs. */
80 
81 typedef struct vn_reference_op_struct
82 {
83  enum tree_code opcode;
84  /* Constant offset this op adds or -1 if it is variable. */
85  HOST_WIDE_INT off;
86  tree type;
87  tree op0;
88  tree op1;
89  tree op2;
90 } vn_reference_op_s;
91 typedef vn_reference_op_s *vn_reference_op_t;
92 typedef const vn_reference_op_s *const_vn_reference_op_t;
93 
94 
95 /* A reference operation in the hashtable is representation as
96  the vuse, representing the memory state at the time of
97  the operation, and a collection of operands that make up the
98  addressing calculation. If two vn_reference_t's have the same set
99  of operands, they access the same memory location. We also store
100  the resulting value number, and the hashcode. */
101 
102 typedef struct vn_reference_s
103 {
104  /* Unique identifier that all expressions with the same value have. */
105  unsigned int value_id;
106  hashval_t hashcode;
107  tree vuse;
108  alias_set_type set;
109  tree type;
110  vec<vn_reference_op_s> operands;
111  tree result;
112  tree result_vdef;
113 } *vn_reference_t;
114 typedef const struct vn_reference_s *const_vn_reference_t;
115 
116 typedef struct vn_constant_s
117 {
118  unsigned int value_id;
119  hashval_t hashcode;
120  tree constant;
121 } *vn_constant_t;
122 
123 enum vn_kind { VN_NONE, VN_CONSTANT, VN_NARY, VN_REFERENCE, VN_PHI };
124 enum vn_kind vn_get_stmt_kind (gimple);
125 
126 /* Hash the type TYPE using bits that distinguishes it in the
127  types_compatible_p sense. */
128 
129 static inline hashval_t
130 vn_hash_type (tree type)
131 {
132  return (INTEGRAL_TYPE_P (type)
133  + (INTEGRAL_TYPE_P (type)
134  ? TYPE_PRECISION (type) + TYPE_UNSIGNED (type) : 0));
135 }
136 
137 /* Hash the constant CONSTANT with distinguishing type incompatible
138  constants in the types_compatible_p sense. */
139 
140 static inline hashval_t
141 vn_hash_constant_with_type (tree constant)
142 {
143  return (iterative_hash_expr (constant, 0)
144  + vn_hash_type (TREE_TYPE (constant)));
145 }
146 
147 /* Compare the constants C1 and C2 with distinguishing type incompatible
148  constants in the types_compatible_p sense. */
149 
150 static inline bool
151 vn_constant_eq_with_type (tree c1, tree c2)
152 {
153  return (expressions_equal_p (c1, c2)
154  && types_compatible_p (TREE_TYPE (c1), TREE_TYPE (c2)));
155 }
156 
157 typedef struct vn_ssa_aux
158 {
159  /* Value number. This may be an SSA name or a constant. */
160  tree valnum;
161  /* Representative expression, if not a direct constant. */
162  tree expr;
163 
164  /* Unique identifier that all expressions with the same value have. */
165  unsigned int value_id;
166 
167  /* SCC information. */
168  unsigned int dfsnum;
169  unsigned int low;
170  unsigned visited : 1;
171  unsigned on_sccstack : 1;
172 
173  /* Whether the representative expression contains constants. */
174  unsigned has_constants : 1;
175  /* Whether the SSA_NAME has been value numbered already. This is
176  only saying whether visit_use has been called on it at least
177  once. It cannot be used to avoid visitation for SSA_NAME's
178  involved in non-singleton SCC's. */
179  unsigned use_processed : 1;
180 
181  /* Whether the SSA_NAME has no defining statement and thus an
182  insertion of such with EXPR as definition is required before
183  a use can be created of it. */
184  unsigned needs_insertion : 1;
185 } *vn_ssa_aux_t;
186 
187 typedef enum { VN_NOWALK, VN_WALK, VN_WALKREWRITE } vn_lookup_kind;
188 
189 /* Return the value numbering info for an SSA_NAME. */
190 extern vn_ssa_aux_t VN_INFO (tree);
191 extern vn_ssa_aux_t VN_INFO_GET (tree);
192 tree vn_get_expr_for (tree);
193 bool run_scc_vn (vn_lookup_kind);
194 void free_scc_vn (void);
195 tree vn_nary_op_lookup (tree, vn_nary_op_t *);
196 tree vn_nary_op_lookup_stmt (gimple, vn_nary_op_t *);
197 tree vn_nary_op_lookup_pieces (unsigned int, enum tree_code,
198  tree, tree *, vn_nary_op_t *);
199 vn_nary_op_t vn_nary_op_insert (tree, tree);
200 vn_nary_op_t vn_nary_op_insert_stmt (gimple, tree);
201 vn_nary_op_t vn_nary_op_insert_pieces (unsigned int, enum tree_code,
202  tree, tree *, tree, unsigned int);
203 void vn_reference_fold_indirect (vec<vn_reference_op_s> *,
204  unsigned int *);
205 void copy_reference_ops_from_ref (tree, vec<vn_reference_op_s> *);
206 void copy_reference_ops_from_call (gimple, vec<vn_reference_op_s> *);
207 bool ao_ref_init_from_vn_reference (ao_ref *, alias_set_type, tree,
208  vec<vn_reference_op_s> );
209 tree vn_reference_lookup_pieces (tree, alias_set_type, tree,
210  vec<vn_reference_op_s> ,
211  vn_reference_t *, vn_lookup_kind);
212 tree vn_reference_lookup (tree, tree, vn_lookup_kind, vn_reference_t *);
213 vn_reference_t vn_reference_insert (tree, tree, tree, tree);
214 vn_reference_t vn_reference_insert_pieces (tree, alias_set_type, tree,
215  vec<vn_reference_op_s> ,
216  tree, unsigned int);
217 
218 hashval_t vn_nary_op_compute_hash (const vn_nary_op_t);
219 bool vn_nary_op_eq (const_vn_nary_op_t const vno1,
220  const_vn_nary_op_t const vno2);
221 bool vn_nary_may_trap (vn_nary_op_t);
222 hashval_t vn_reference_compute_hash (const vn_reference_t);
223 bool vn_reference_eq (const_vn_reference_t const, const_vn_reference_t const);
224 unsigned int get_max_value_id (void);
225 unsigned int get_next_value_id (void);
226 unsigned int get_constant_value_id (tree);
227 unsigned int get_or_alloc_constant_value_id (tree);
228 bool value_id_constant_p (unsigned int);
229 tree fully_constant_vn_reference_p (vn_reference_t);
230 
231 /* Valueize NAME if it is an SSA name, otherwise just return it. */
232 
233 static inline tree
234 vn_valueize (tree name)
235 {
236  if (TREE_CODE (name) == SSA_NAME)
237  {
238  tree tem = VN_INFO (name)->valnum;
239  return tem == VN_TOP ? name : tem;
240  }
241  return name;
242 }
243 
244 #endif /* TREE_SSA_SCCVN_H */