libgcc/config/i386/cygming-crtbegin.c

   1 /* crtbegin object for windows32 targets.
   2    Copyright (C) 2007-2015 Free Software Foundation, Inc.
   3
   4    Contributed by Danny Smith <dannysmith@users.sourceforge.net>
   5
   6 This file is part of GCC.
   7
   8 GCC is free software; you can redistribute it and/or modify it under
   9 the terms of the GNU General Public License as published by the Free
  10 Software Foundation; either version 3, or (at your option) any later
  11 version.
  12
  13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  15 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  16 for more details.
  17
  18 Under Section 7 of GPL version 3, you are granted additional
  19 permissions described in the GCC Runtime Library Exception, version
  20 3.1, as published by the Free Software Foundation.
  21
  22 You should have received a copy of the GNU General Public License and
  23 a copy of the GCC Runtime Library Exception along with this program;
  24 see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  25 <http://www.gnu.org/licenses/>.  */
  26
  27 /* Target machine header files require this define. */
  28 #define IN_LIBGCC2
  29
  30 #include "auto-host.h"
  31 #include "tconfig.h"
  32 #include "tsystem.h"
  33 #include "coretypes.h"
  34 #include "tm.h"
  35 #include "libgcc_tm.h"
  36 #include "unwind-dw2-fde.h"
  37
  38 #define WIN32_LEAN_AND_MEAN
  39 #include <windows.h>
  40
  41 #ifndef LIBGCC_SONAME
  42 #define LIBGCC_SONAME "libgcc_s.dll"
  43 #endif
  44
  45 #ifndef LIBGCJ_SONAME
  46 #define LIBGCJ_SONAME "libgcj_s.dll"
  47 #endif
  48
  49 #if DWARF2_UNWIND_INFO
  50 /* Make the declarations weak.  This is critical for
  51    _Jv_RegisterClasses because it lives in libgcj.a  */
  52 extern void __register_frame_info (__attribute__((unused)) const void *,
  53                                    __attribute__((unused)) struct object *)
  54                                    TARGET_ATTRIBUTE_WEAK;
  55 extern void *__deregister_frame_info (__attribute__((unused)) const void *)
  56                                       TARGET_ATTRIBUTE_WEAK;
  57
  58 /* Work around for current cygwin32 build problems (Bug gas/16858).
  59    Compile weak default functions only for 64-bit systems,
  60    when absolutely necessary.  */
  61 #ifdef __x86_64__
  62 TARGET_ATTRIBUTE_WEAK void
  63 __register_frame_info (__attribute__((unused)) const void *p,
  64                        __attribute__((unused)) struct object *o)
  65 {
  66 }
  67
  68 TARGET_ATTRIBUTE_WEAK void *
  69 __deregister_frame_info (__attribute__((unused)) const void *p)
  70 {
  71   return (void*) 0;
  72 }
  73 #endif
  74 #endif /* DWARF2_UNWIND_INFO */
  75
  76 #if TARGET_USE_JCR_SECTION
  77 extern void _Jv_RegisterClasses (__attribute__((unused)) const void *)
  78   TARGET_ATTRIBUTE_WEAK;
  79
  80 #ifdef __x86_64__
  81 TARGET_ATTRIBUTE_WEAK void
  82 _Jv_RegisterClasses (__attribute__((unused)) const void *p)
  83 {
  84 }
  85 #endif
  86 #endif /* TARGET_USE_JCR_SECTION */
  87
  88 #if defined(HAVE_LD_RO_RW_SECTION_MIXING)
  89 # define EH_FRAME_SECTION_CONST const
  90 #else
  91 # define EH_FRAME_SECTION_CONST
  92 #endif
  93
  94 /* Stick a label at the beginning of the frame unwind info so we can
  95    register/deregister it with the exception handling library code.  */
  96 #if DWARF2_UNWIND_INFO
  97 static EH_FRAME_SECTION_CONST char __EH_FRAME_BEGIN__[]
  98   __attribute__((used, section(__LIBGCC_EH_FRAME_SECTION_NAME__), aligned(4)))
  99   = { };
 100
 101 static struct object obj;
 102
 103 /* Handle of libgcc's DLL reference.  */
 104 HANDLE hmod_libgcc;
 105 static void *  (*deregister_frame_fn) (const void *) = NULL;
 106 #endif
 107
 108 #if TARGET_USE_JCR_SECTION
 109 static void *__JCR_LIST__[]
 110   __attribute__ ((used, section(__LIBGCC_JCR_SECTION_NAME__), aligned(4)))
 111   = { };
 112 #endif
 113
 114 #ifdef __CYGWIN__
 115 /* Declare the __dso_handle variable.  It should have a unique value
 116    in every shared-object; in a main program its value is zero.  The
 117    object should in any case be protected.  This means the instance
 118    in one DSO or the main program is not used in another object.  The
 119    dynamic linker takes care of this.  */
 120
 121 #ifdef CRTSTUFFS_O
 122 extern void *__ImageBase;
 123 void *__dso_handle = &__ImageBase;
 124 #else
 125 void *__dso_handle = 0;
 126 #endif
 127
 128 #endif /* __CYGWIN__ */
 129
 130
 131 /* Pull in references from libgcc.a(unwind-dw2-fde.o) in the
 132    startfile. These are referenced by a ctor and dtor in crtend.o.  */
 133 extern void __gcc_register_frame (void);
 134 extern void __gcc_deregister_frame (void);
 135
 136 void
 137 __gcc_register_frame (void)
 138 {
 139 #if DWARF2_UNWIND_INFO
 140 /* Weak undefined symbols won't be pulled in from dlls; hence
 141    we first test if the dll is already loaded and, if so,
 142    get the symbol's address at run-time.  If the dll is not loaded,
 143    fallback to weak linkage to static archive.  */
 144
 145   void (*register_frame_fn) (const void *, struct object *);
 146   HANDLE h = GetModuleHandle (LIBGCC_SONAME);
 147
 148   if (h)
 149     {
 150       /* Increasing the load-count of LIBGCC_SONAME DLL.  */
 151       hmod_libgcc = LoadLibrary (LIBGCC_SONAME);
 152       register_frame_fn = (void (*) (const void *, struct object *))
 153                           GetProcAddress (h, "__register_frame_info");
 154       deregister_frame_fn = (void* (*) (const void *))
 155                             GetProcAddress (h, "__deregister_frame_info");
 156     }
 157   else
 158     {
 159       register_frame_fn = __register_frame_info;
 160       deregister_frame_fn = __deregister_frame_info;
 161     }
 162   if (register_frame_fn)
 163      register_frame_fn (__EH_FRAME_BEGIN__, &obj);
 164 #endif
 165
 166 #if TARGET_USE_JCR_SECTION
 167   if (__JCR_LIST__[0])
 168     {
 169       void (*register_class_fn) (const void *);
 170       HANDLE h = GetModuleHandle (LIBGCJ_SONAME);
 171       if (h)
 172         register_class_fn = (void (*) (const void *))
 173                              GetProcAddress (h, "_Jv_RegisterClasses");
 174       else
 175         register_class_fn = _Jv_RegisterClasses;
 176
 177       if (register_class_fn)
 178         register_class_fn (__JCR_LIST__);
 179     }
 180 #endif
 181
 182 #if DEFAULT_USE_CXA_ATEXIT
 183   /* If we use the __cxa_atexit method to register C++ dtors
 184      at object construction,  also use atexit to register eh frame
 185      info cleanup.  */
 186   atexit(__gcc_deregister_frame);
 187 #endif /* DEFAULT_USE_CXA_ATEXIT */
 188 }
 189
 190 void
 191 __gcc_deregister_frame (void)
 192 {
 193 #if DWARF2_UNWIND_INFO
 194   if (deregister_frame_fn)
 195      deregister_frame_fn (__EH_FRAME_BEGIN__);
 196   if (hmod_libgcc)
 197     FreeLibrary (hmod_libgcc);
 198 #endif
 199 }