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) 2005-2018 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
  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
  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
  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
  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
  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 }