1 /*

     2  * Copyright (C) 2006 Apple Computer, Inc.

     3  *

     4  * This library is free software; you can redistribute it and/or

     5  * modify it under the terms of the GNU Library General Public

     6  * License as published by the Free Software Foundation; either

     7  * version 2 of the License, or (at your option) any later version.

     8  *

     9  * This library is distributed in the hope that it will be useful,

    10  * but WITHOUT ANY WARRANTY; without even the implied warranty of

    11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

    12  * Library General Public License for more details.

    13  *

    14  * You should have received a copy of the GNU Library General Public License

    15  * along with this library; see the file COPYING.LIB.  If not, write to

    16  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,

    17  * Boston, MA 02110-1301, USA.

    18  *

    19  */

    20 

    21 #ifndef StaticConstructors_h

    22 #define StaticConstructors_h

    23 

    24 // We need to avoid having static constructors. We achieve this

    25 // with two separate methods for GCC and MSVC. Both methods prevent the static

    26 // initializers from being registered and called on program startup. On GCC, we

    27 // declare the global objects with a different type that can be POD default

    28 // initialized by the linker/loader. On MSVC we use a special compiler feature

    29 // to have the CRT ignore our static initializers. The constructors will never

    30 // be called and the objects will be left uninitialized.

    31 //

    32 // With both of these approaches, we must define and explicitly call an init

    33 // routine that uses placement new to create the objects and overwrite the

    34 // uninitialized placeholders.

    35 //

    36 // This is not completely portable, but is what we have for now without

    37 // changing how a lot of code accesses these global objects.

    38 

    39 #ifdef SKIP_STATIC_CONSTRUCTORS_ON_MSVC

    40 // - Assume that all includes of this header want ALL of their static

    41 //   initializers ignored. This is currently the case. This means that if

    42 //   a .cc includes this header (or it somehow gets included), all static

    43 //   initializers after the include will not be executed.

    44 // - We do this with a pragma, so that all of the static initializer pointers

    45 //   go into our own section, and the CRT won't call them. Eventually it would

    46 //   be nice if the section was discarded, because we don't want the pointers.

    47 //   See: http://msdn.microsoft.com/en-us/library/7977wcck(VS.80).aspx

    48 #pragma warning(disable:4075)

    49 #pragma init_seg(".unwantedstaticinits")

    50 #endif

    51 

    52 #ifndef SKIP_STATIC_CONSTRUCTORS_ON_GCC

    53     // Define an global in the normal way.

    54 #if COMPILER(MSVC7_OR_LOWER)

    55 #define DEFINE_GLOBAL(type, name) \

    56     const type name;

    57 #elif COMPILER(WINSCW)

    58 #define DEFINE_GLOBAL(type, name, arg...) \

    59     const type name;

    60 #else

    61 #define DEFINE_GLOBAL(type, name, ...) \

    62     const type name;

    63 #endif

    64 

    65 #else

    66 // Define an correctly-sized array of pointers to avoid static initialization.

    67 // Use an array of pointers instead of an array of char in case there is some alignment issue.

    68 #if COMPILER(MSVC7_OR_LOWER)

    69 #define DEFINE_GLOBAL(type, name) \

    70     void * name[(sizeof(type) + sizeof(void *) - 1) / sizeof(void *)];

    71 #elif COMPILER(WINSCW)

    72 #define DEFINE_GLOBAL(type, name, arg...) \

    73     void * name[(sizeof(type) + sizeof(void *) - 1) / sizeof(void *)];

    74 #else

    75 #define DEFINE_GLOBAL(type, name, ...) \

    76     void * name[(sizeof(type) + sizeof(void *) - 1) / sizeof(void *)];

    77 #endif

    78 #endif

    79 

    80 #endif // StaticConstructors_h