1 /* Tree based alias analysis and alias oracle.
2    Copyright (C) 2008-2022 Free Software Foundation, Inc.
3    Contributed by Richard Guenther  <rguenther@suse.de>
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_ALIAS_H
22 #define TREE_SSA_ALIAS_H
23 
24 /* The points-to solution.
25 
26    The points-to solution is a union of pt_vars and the abstract
27    sets specified by the flags.  */
28 struct GTY(()) pt_solution
29 {
30   /* Nonzero if points-to analysis couldn't determine where this pointer
31      is pointing to.  */
32   unsigned int anything : 1;
33 
34   /* Nonzero if the points-to set includes any global memory.  Note that
35      even if this is zero pt_vars can still include global variables.  */
36   unsigned int nonlocal : 1;
37 
38   /* Nonzero if the points-to set includes the local escaped solution by
39      reference.  */
40   unsigned int escaped : 1;
41 
42   /* Nonzero if the points-to set includes the IPA escaped solution by
43      reference.  */
44   unsigned int ipa_escaped : 1;
45 
46   /* Nonzero if the points-to set includes 'nothing', the points-to set
47      includes memory at address NULL.  */
48   unsigned int null : 1;
49 
50   /* Nonzero if the vars bitmap includes a variable included in 'nonlocal'.  */
51   unsigned int vars_contains_nonlocal : 1;
52   /* Nonzero if the vars bitmap includes a variable included in 'escaped'.  */
53   unsigned int vars_contains_escaped : 1;
54   /* Nonzero if the vars bitmap includes a anonymous heap variable that
55      escaped the function and thus became global.  */
56   unsigned int vars_contains_escaped_heap : 1;
57   /* Nonzero if the vars bitmap includes a anonymous variable used to
58      represent storage pointed to by a restrict qualified pointer.  */
59   unsigned int vars_contains_restrict : 1;
60   /* Nonzero if the vars bitmap includes an interposable variable.  */
61   unsigned int vars_contains_interposable : 1;
62 
63   /* Set of variables that this pointer may point to.  */
64   bitmap vars;
65 };
66 
67 
68 /* Simplified and cached information about a memory reference tree.
69    Used by the alias-oracle internally and externally in alternate
70    interfaces.  */
71 class ao_ref
72 {
73 public:
74   /* The original full memory reference tree or NULL_TREE if that is
75      not available.  */
76   tree ref;
77 
78   /* The following fields are the decomposed reference as returned
79      by get_ref_base_and_extent.  */
80   /* The base object of the memory reference or NULL_TREE if all of
81      the following fields are not yet computed.  */
82   tree base;
83   /* The offset relative to the base.  */
84   poly_int64 offset;
85   /* The size of the access.  */
86   poly_int64 size;
87   /* The maximum possible extent of the access or -1 if unconstrained.  */
88   poly_int64 max_size;
89 
90   /* The alias set of the access or -1 if not yet computed.  */
91   alias_set_type ref_alias_set;
92 
93   /* The alias set of the base object or -1 if not yet computed.  */
94   alias_set_type base_alias_set;
95 
96   /* Whether the memory is considered a volatile access.  */
97   bool volatile_p;
98 
99   bool max_size_known_p () const;
100 };
101 
102 /* Return true if the maximum size is known, rather than the special -1
103    marker.  */
104 
105 inline bool
max_size_known_p()106 ao_ref::max_size_known_p () const
107 {
108   return known_size_p (max_size);
109 }
110 
111 /* In tree-ssa-alias.cc  */
112 extern void ao_ref_init (ao_ref *, tree);
113 extern void ao_ref_init_from_ptr_and_size (ao_ref *, tree, tree);
114 extern void ao_ref_init_from_ptr_and_range (ao_ref *, tree, bool,
115                                                       poly_int64, poly_int64,
116                                                       poly_int64);
117 extern tree ao_ref_base (ao_ref *);
118 extern alias_set_type ao_ref_alias_set (ao_ref *);
119 extern alias_set_type ao_ref_base_alias_set (ao_ref *);
120 extern tree ao_ref_alias_ptr_type (ao_ref *);
121 extern tree ao_ref_base_alias_ptr_type (ao_ref *);
122 extern bool ao_ref_alignment (ao_ref *, unsigned int *,
123                                     unsigned HOST_WIDE_INT *);
124 extern bool ptr_deref_may_alias_global_p (tree, bool);
125 extern bool ptr_derefs_may_alias_p (tree, tree);
126 extern bool ptrs_compare_unequal (tree, tree);
127 extern bool ref_may_alias_global_p (tree, bool);
128 extern bool ref_may_alias_global_p (ao_ref *, bool);
129 extern bool refs_may_alias_p (tree, tree, bool = true);
130 extern bool refs_may_alias_p_1 (ao_ref *, ao_ref *, bool);
131 extern bool refs_anti_dependent_p (tree, tree);
132 extern bool refs_output_dependent_p (tree, tree);
133 extern bool ref_maybe_used_by_stmt_p (gimple *, tree, bool = true);
134 extern bool ref_maybe_used_by_stmt_p (gimple *, ao_ref *, bool = true);
135 extern bool stmt_may_clobber_global_p (gimple *, bool);
136 extern bool stmt_may_clobber_ref_p (gimple *, tree, bool = true);
137 extern bool stmt_may_clobber_ref_p_1 (gimple *, ao_ref *, bool = true);
138 extern bool call_may_clobber_ref_p (gcall *, tree, bool = true);
139 extern bool call_may_clobber_ref_p_1 (gcall *, ao_ref *, bool = true);
140 extern bool stmt_kills_ref_p (gimple *, tree);
141 extern bool stmt_kills_ref_p (gimple *, ao_ref *);
142 enum translate_flags
143   { TR_TRANSLATE, TR_VALUEIZE_AND_DISAMBIGUATE, TR_DISAMBIGUATE };
144 extern tree get_continuation_for_phi (gimple *, ao_ref *, bool,
145                                               unsigned int &, bitmap *, bool,
146                                               void *(*)(ao_ref *, tree, void *,
147                                                             translate_flags *),
148                                               void *, translate_flags
149                                                 = TR_VALUEIZE_AND_DISAMBIGUATE);
150 extern void *walk_non_aliased_vuses (ao_ref *, tree, bool,
151                                              void *(*)(ao_ref *, tree, void *),
152                                              void *(*)(ao_ref *, tree, void *,
153                                                          translate_flags *),
154                                              tree (*)(tree), unsigned &, void *);
155 extern int walk_aliased_vdefs (ao_ref *, tree,
156                                      bool (*)(ao_ref *, tree, void *),
157                                      void *, bitmap *,
158                                      bool *function_entry_reached = NULL,
159                                      unsigned int limit = 0);
160 extern void dump_alias_info (FILE *);
161 extern void debug_alias_info (void);
162 extern void dump_points_to_solution (FILE *, struct pt_solution *);
163 extern void debug (pt_solution &ref);
164 extern void debug (pt_solution *ptr);
165 extern void dump_points_to_info_for (FILE *, tree);
166 extern void debug_points_to_info_for (tree);
167 extern void dump_alias_stats (FILE *);
168 
169 
170 /* In tree-ssa-structalias.cc  */
171 extern unsigned int compute_may_aliases (void);
172 extern bool pt_solution_empty_p (const pt_solution *);
173 extern bool pt_solution_singleton_or_null_p (struct pt_solution *, unsigned *);
174 extern bool pt_solution_includes_global (struct pt_solution *, bool);
175 extern bool pt_solution_includes (struct pt_solution *, const_tree);
176 extern bool pt_solutions_intersect (struct pt_solution *, struct pt_solution *);
177 extern void pt_solution_reset (struct pt_solution *);
178 extern void pt_solution_set (struct pt_solution *, bitmap, bool);
179 extern void pt_solution_set_var (struct pt_solution *, tree);
180 
181 extern void dump_pta_stats (FILE *);
182 
183 extern GTY(()) struct pt_solution ipa_escaped_pt;
184 
185 /* Return true, if the two ranges [POS1, SIZE1] and [POS2, SIZE2]
186    overlap.  SIZE1 and/or SIZE2 can be (unsigned)-1 in which case the
187    range is open-ended.  Otherwise return false.  */
188 
189 static inline bool
ranges_overlap_p(HOST_WIDE_INT pos1,unsigned HOST_WIDE_INT size1,HOST_WIDE_INT pos2,unsigned HOST_WIDE_INT size2)190 ranges_overlap_p (HOST_WIDE_INT pos1,
191                       unsigned HOST_WIDE_INT size1,
192                       HOST_WIDE_INT pos2,
193                       unsigned HOST_WIDE_INT size2)
194 {
195   if (size1 == 0 || size2 == 0)
196     return false;
197   if (pos1 >= pos2
198       && (size2 == (unsigned HOST_WIDE_INT)-1
199             || pos1 < (pos2 + (HOST_WIDE_INT) size2)))
200     return true;
201   if (pos2 >= pos1
202       && (size1 == (unsigned HOST_WIDE_INT)-1
203             || pos2 < (pos1 + (HOST_WIDE_INT) size1)))
204     return true;
205 
206   return false;
207 }
208 
209 
210 
211 #endif /* TREE_SSA_ALIAS_H  */
212