1 /* Target support for C++ classes on Windows.
2 Contributed by Danny Smith (dannysmith@users.sourceforge.net)
3 Copyright (C) 2005-2021 Free Software Foundation, Inc.
4
5 This file is part of GCC.
6
7 GCC is free software; you can redistribute it and/or modify it under
8 the terms of the GNU General Public License as published by the Free
9 Software Foundation; either version 3, or (at your option) any later
10 version.
11
12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
15 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 #define IN_TARGET_CODE 1
22
23 #include "config.h"
24 #include "system.h"
25 #include "coretypes.h"
26 #include "cp/cp-tree.h" /* This is why we're a separate module. */
27 #include "stringpool.h"
28 #include "attribs.h"
29
30 bool
i386_pe_type_dllimport_p(tree decl)31 i386_pe_type_dllimport_p (tree decl)
32 {
33 gcc_assert (TREE_CODE (decl) == VAR_DECL
34 || TREE_CODE (decl) == FUNCTION_DECL);
35
36 if (TARGET_NOP_FUN_DLLIMPORT && TREE_CODE (decl) == FUNCTION_DECL)
37 return false;
38
39 /* We ignore the dllimport attribute for inline member functions.
40 This differs from MSVC behavior which treats it like GNUC
41 'extern inline' extension. Also ignore for template
42 instantiations with linkonce semantics and artificial methods. */
43 if (TREE_CODE (decl) == FUNCTION_DECL
44 && (DECL_DECLARED_INLINE_P (decl)
45 || DECL_TEMPLATE_INSTANTIATION (decl)
46 || DECL_ARTIFICIAL (decl)))
47 return false;
48
49 /* Overrides of the class dllimport decls by out-of-class definitions are
50 handled by tree.c:merge_dllimport_decl_attributes. */
51 return true;
52 }
53
54 bool
i386_pe_type_dllexport_p(tree decl)55 i386_pe_type_dllexport_p (tree decl)
56 {
57 gcc_assert (TREE_CODE (decl) == VAR_DECL
58 || TREE_CODE (decl) == FUNCTION_DECL);
59
60 /* Avoid exporting compiler-generated default dtors and copy ctors.
61 The only artificial methods that need to be exported are virtual
62 and non-virtual thunks. */
63 if (TREE_CODE (TREE_TYPE (decl)) == METHOD_TYPE
64 && DECL_ARTIFICIAL (decl) && !DECL_THUNK_P (decl))
65 return false;
66 if (TREE_CODE (decl) == FUNCTION_DECL
67 && DECL_DECLARED_INLINE_P (decl))
68 {
69 if (DECL_REALLY_EXTERN (decl)
70 || !flag_keep_inline_dllexport)
71 return false;
72 }
73 return true;
74 }
75
maybe_add_dllimport(tree decl)76 static inline void maybe_add_dllimport (tree decl)
77 {
78 if (i386_pe_type_dllimport_p (decl))
79 DECL_DLLIMPORT_P (decl) = 1;
80 }
81
maybe_add_dllexport(tree decl)82 static inline void maybe_add_dllexport (tree decl)
83 {
84 if (i386_pe_type_dllexport_p (decl))
85 {
86 tree decl_attrs = DECL_ATTRIBUTES (decl);
87 if (lookup_attribute ("dllexport", decl_attrs) != NULL_TREE)
88 /* Already done. */
89 return;
90 DECL_ATTRIBUTES (decl) = tree_cons (get_identifier ("dllexport"),
91 NULL_TREE, decl_attrs);
92 }
93 }
94
95 void
i386_pe_adjust_class_at_definition(tree t)96 i386_pe_adjust_class_at_definition (tree t)
97 {
98 tree member;
99
100 gcc_assert (CLASS_TYPE_P (t));
101
102
103 if (lookup_attribute ("dllexport", TYPE_ATTRIBUTES (t)) != NULL_TREE)
104 {
105 tree tmv = TYPE_MAIN_VARIANT (t);
106
107 /* Make sure that we set dllexport attribute to typeinfo's
108 base declaration, as otherwise it would fail to be exported as
109 it isn't a class-member. */
110 if (tmv != NULL_TREE
111 && CLASSTYPE_TYPEINFO_VAR (tmv) != NULL_TREE)
112 {
113 tree na, ti_decl = CLASSTYPE_TYPEINFO_VAR (tmv);
114 na = tree_cons (get_identifier ("dllexport"), NULL_TREE,
115 NULL_TREE);
116 decl_attributes (&ti_decl, na, 0);
117 }
118
119 /* Check FUNCTION_DECL's and static VAR_DECL's. */
120 for (member = TYPE_FIELDS (t); member; member = DECL_CHAIN (member))
121 if (TREE_CODE (member) == VAR_DECL)
122 maybe_add_dllexport (member);
123 else if (TREE_CODE (member) == FUNCTION_DECL)
124 {
125 tree thunk;
126 maybe_add_dllexport (member);
127
128 /* Also add the attribute to its thunks. */
129 for (thunk = DECL_THUNKS (member); thunk;
130 thunk = TREE_CHAIN (thunk))
131 maybe_add_dllexport (thunk);
132 }
133
134 /* Check vtables */
135 for (member = CLASSTYPE_VTABLES (t);
136 member; member = DECL_CHAIN (member))
137 if (TREE_CODE (member) == VAR_DECL)
138 maybe_add_dllexport (member);
139 }
140
141 else if (lookup_attribute ("dllimport", TYPE_ATTRIBUTES (t)) != NULL_TREE)
142 {
143 /* We don't actually add the attribute to the decl, just set the flag
144 that signals that the address of this symbol is not a compile-time
145 constant. Any subsequent out-of-class declaration of members wil
146 cause the DECL_DLLIMPORT_P flag to be unset.
147 (See tree.c: merge_dllimport_decl_attributes).
148 That is just right since out-of class declarations can only be a
149 definition. */
150
151 /* Check FUNCTION_DECL's and static VAR_DECL's. */
152 for (member = TYPE_FIELDS (t); member; member = DECL_CHAIN (member))
153 if (TREE_CODE (member) == VAR_DECL)
154 maybe_add_dllimport (member);
155 else if (TREE_CODE (member) == FUNCTION_DECL)
156 {
157 tree thunk;
158 maybe_add_dllimport (member);
159
160 /* Also add the attribute to its thunks. */
161 for (thunk = DECL_THUNKS (member); thunk;
162 thunk = DECL_CHAIN (thunk))
163 maybe_add_dllimport (thunk);
164 }
165
166 /* Check vtables */
167 for (member = CLASSTYPE_VTABLES (t);
168 member; member = DECL_CHAIN (member))
169 if (TREE_CODE (member) == VAR_DECL)
170 maybe_add_dllimport (member);
171
172 /* We leave typeinfo tables alone. We can't mark TI objects as
173 dllimport, since the address of a secondary VTT may be needed
174 for static initialization of a primary VTT. VTT's of
175 dllimport'd classes should always be link-once COMDAT. */
176 }
177 }
178