WebCore/platform/StaticConstructors.h

   1 /*
   2  * This file is part of the DOM implementation for KDE.
   3  *
   4  * Copyright (C) 2006 Apple Computer, Inc.
   5  *
   6  * This library is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Library General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2 of the License, or (at your option) any later version.
  10  *
  11  * This library is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Library General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Library General Public License
  17  * along with this library; see the file COPYING.LIB.  If not, write to
  18  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  19  * Boston, MA 02110-1301, USA.
  20  *
  21  */
  22
  23 #ifndef StaticConstructors_h
  24 #define StaticConstructors_h
  25
  26 // For WebCore we need to avoid having static constructors. We achieve this
  27 // with two separate methods for GCC and MSVC. Both methods prevent the static
  28 // initializers from being registered and called on program startup. On GCC, we
  29 // declare the global objects with a different type that can be POD default
  30 // initialized by the linker/loader. On MSVC we use a special compiler feature
  31 // to have the CRT ignore our static initializers. The constructors will never
  32 // be called and the objects will be left uninitialized.
  33 //
  34 // With both of these approaches, we must define and explicitly call an init
  35 // routine that uses placement new to create the objects and overwrite the
  36 // uninitialized placeholders.
  37 //
  38 // This is not completely portable, but is what we have for now without
  39 // changing how a lot of code accesses these global objects.
  40
  41 #ifdef SKIP_STATIC_CONSTRUCTORS_ON_MSVC
  42 // - Assume that all includes of this header want ALL of their static
  43 //   initializers ignored. This is currently the case. This means that if
  44 //   a .cc includes this header (or it somehow gets included), all static
  45 //   initializers after the include will not be executed.
  46 // - We do this with a pragma, so that all of the static initializer pointers
  47 //   go into our own section, and the CRT won't call them. Eventually it would
  48 //   be nice if the section was discarded, because we don't want the pointers.
  49 //   See: http://msdn.microsoft.com/en-us/library/7977wcck(VS.80).aspx
  50 #pragma warning(disable:4075)
  51 #pragma init_seg(".unwantedstaticinits")
  52 #endif
  53
  54 #ifndef SKIP_STATIC_CONSTRUCTORS_ON_GCC
  55     // Define an global in the normal way.
  56 #if COMPILER(MSVC7)
  57 #define DEFINE_GLOBAL(type, name) \
  58     const type name;
  59 #else
  60 #define DEFINE_GLOBAL(type, name, ...) \
  61     const type name;
  62 #endif
  63
  64 #else
  65 // Define an correctly-sized array of pointers to avoid static initialization.
  66 // Use an array of pointers instead of an array of char in case there is some alignment issue.
  67 #if COMPILER(MSVC7)
  68 #define DEFINE_GLOBAL(type, name) \
  69     void * name[(sizeof(type) + sizeof(void *) - 1) / sizeof(void *)];
  70 #else
  71 #define DEFINE_GLOBAL(type, name, ...) \
  72     void * name[(sizeof(type) + sizeof(void *) - 1) / sizeof(void *)];
  73 #endif
  74 #endif
  75
  76 #endif // StaticConstructors_h