gcc/config/i386/winnt-cxx.c

   1 /* Target support for C++ classes on Windows.
   2    Contributed by Danny Smith (dannysmith@users.sourceforge.net)
   3    Copyright (C) 2005-2017 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 #include "config.h"
  22 #include "system.h"
  23 #include "coretypes.h"
  24 #include "cp/cp-tree.h" /* This is why we're a separate module.  */
  25 #include "stringpool.h"
  26 #include "attribs.h"
  27
  28 bool
  29 i386_pe_type_dllimport_p (tree decl)
  30 {
  31   gcc_assert (TREE_CODE (decl) == VAR_DECL
  32               || TREE_CODE (decl) == FUNCTION_DECL);
  33
  34   if (TARGET_NOP_FUN_DLLIMPORT && TREE_CODE (decl) == FUNCTION_DECL)
  35     return false;
  36
  37   /* We ignore the dllimport attribute for inline member functions.
  38      This differs from MSVC behavior which treats it like GNUC
  39      'extern inline' extension.  Also ignore for template
  40      instantiations with linkonce semantics and artificial methods.  */
  41   if (TREE_CODE (decl) ==  FUNCTION_DECL
  42       && (DECL_DECLARED_INLINE_P (decl)
  43           || DECL_TEMPLATE_INSTANTIATION (decl)
  44           || DECL_ARTIFICIAL (decl)))
  45     return false;
  46
  47   /* Overrides of the class dllimport decls by out-of-class definitions are
  48      handled by tree.c:merge_dllimport_decl_attributes.   */
  49   return true;
  50 }
  51
  52 bool
  53 i386_pe_type_dllexport_p (tree decl)
  54 {
  55   gcc_assert (TREE_CODE (decl) == VAR_DECL
  56               || TREE_CODE (decl) == FUNCTION_DECL);
  57
  58   /* Avoid exporting compiler-generated default dtors and copy ctors.
  59      The only artificial methods that need to be exported are virtual
  60      and non-virtual thunks.  */
  61   if (TREE_CODE (TREE_TYPE (decl)) == METHOD_TYPE
  62       && DECL_ARTIFICIAL (decl) && !DECL_THUNK_P (decl))
  63     return false;
  64   if (TREE_CODE (decl) == FUNCTION_DECL
  65       && DECL_DECLARED_INLINE_P (decl))
  66     {
  67       if (DECL_REALLY_EXTERN (decl)
  68           || !flag_keep_inline_dllexport)
  69         return false;
  70     }
  71   return true;
  72 }
  73
  74 static inline void maybe_add_dllimport (tree decl)
  75 {
  76   if (i386_pe_type_dllimport_p (decl))
  77     DECL_DLLIMPORT_P (decl) = 1;
  78 }
  79
  80 static inline void maybe_add_dllexport (tree decl)
  81 {
  82   if (i386_pe_type_dllexport_p (decl))
  83     {
  84       tree decl_attrs = DECL_ATTRIBUTES (decl);
  85       if (lookup_attribute ("dllexport", decl_attrs) != NULL_TREE)
  86         /* Already done.  */
  87         return;
  88       DECL_ATTRIBUTES (decl) = tree_cons (get_identifier ("dllexport"),
  89                                           NULL_TREE, decl_attrs);
  90     }
  91 }
  92
  93 void
  94 i386_pe_adjust_class_at_definition (tree t)
  95 {
  96   tree member;
  97
  98   gcc_assert (CLASS_TYPE_P (t));
  99
 100
 101   if (lookup_attribute ("dllexport", TYPE_ATTRIBUTES (t)) != NULL_TREE)
 102     {
 103       tree tmv = TYPE_MAIN_VARIANT (t);
 104
 105       /* Make sure that we set dllexport attribute to typeinfo's
 106          base declaration, as otherwise it would fail to be exported as
 107          it isn't a class-member.  */
 108       if (tmv != NULL_TREE
 109           && CLASSTYPE_TYPEINFO_VAR (tmv) != NULL_TREE)
 110         {
 111           tree na, ti_decl = CLASSTYPE_TYPEINFO_VAR (tmv);
 112           na = tree_cons (get_identifier ("dllexport"), NULL_TREE,
 113                           NULL_TREE);
 114           decl_attributes (&ti_decl, na, 0);
 115         }
 116
 117       /* Check FUNCTION_DECL's and static VAR_DECL's.  */
 118       for (member = TYPE_FIELDS (t); member; member = DECL_CHAIN (member))
 119         if (TREE_CODE (member) == VAR_DECL)
 120           maybe_add_dllexport (member);
 121         else if (TREE_CODE (member) == FUNCTION_DECL)
 122           {
 123             tree thunk;
 124             maybe_add_dllexport (member);
 125
 126             /* Also add the attribute to its thunks.  */
 127             for (thunk = DECL_THUNKS (member); thunk;
 128                  thunk = TREE_CHAIN (thunk))
 129               maybe_add_dllexport (thunk);
 130           }
 131
 132       /* Check vtables  */
 133       for (member = CLASSTYPE_VTABLES (t);
 134            member; member = DECL_CHAIN (member))
 135         if (TREE_CODE (member) == VAR_DECL)
 136           maybe_add_dllexport (member);
 137     }
 138
 139   else if (lookup_attribute ("dllimport", TYPE_ATTRIBUTES (t)) != NULL_TREE)
 140     {
 141       /* We don't actually add the attribute to the decl, just set the flag
 142          that signals that the address of this symbol is not a compile-time
 143          constant.   Any subsequent out-of-class declaration of members wil
 144          cause the DECL_DLLIMPORT_P flag to be unset.
 145          (See  tree.c: merge_dllimport_decl_attributes).
 146          That is just right since out-of class declarations can only be a
 147          definition.   */
 148
 149       /* Check FUNCTION_DECL's and static VAR_DECL's.  */
 150       for (member = TYPE_FIELDS (t); member; member = DECL_CHAIN (member))
 151         if (TREE_CODE (member) == VAR_DECL)
 152           maybe_add_dllimport (member);
 153         else if (TREE_CODE (member) == FUNCTION_DECL)
 154           {
 155             tree thunk;
 156             maybe_add_dllimport (member);
 157
 158             /* Also add the attribute to its thunks.  */
 159             for (thunk = DECL_THUNKS (member); thunk;
 160                  thunk = DECL_CHAIN (thunk))
 161               maybe_add_dllimport (thunk);
 162           }
 163
 164       /* Check vtables  */
 165       for (member = CLASSTYPE_VTABLES (t);
 166            member;  member = DECL_CHAIN (member))
 167         if (TREE_CODE (member) == VAR_DECL)
 168           maybe_add_dllimport (member);
 169
 170       /* We leave typeinfo tables alone.  We can't mark TI objects as
 171         dllimport, since the address of a secondary VTT may be needed
 172         for static initialization of a primary VTT.  VTT's  of
 173         dllimport'd classes should always be link-once COMDAT.  */
 174     }
 175 }