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 81