| /* Specialized bits of code needed to support construction and |
| destruction of file-scope objects in C++ code. |
| Copyright (C) 1991, 94, 95, 96, 97, 1998 Free Software Foundation, Inc. |
| Contributed by Ron Guilmette (rfg@monkeys.com). |
| |
| This file is part of GNU CC. |
| |
| GNU CC is free software; you can redistribute it and/or modify |
| it under the terms of the GNU General Public License as published by |
| the Free Software Foundation; either version 2, or (at your option) |
| any later version. |
| |
| GNU CC is distributed in the hope that it will be useful, |
| but WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| GNU General Public License for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with GNU CC; see the file COPYING. If not, write to |
| the Free Software Foundation, 59 Temple Place - Suite 330, |
| Boston, MA 02111-1307, USA. */ |
| |
| /* As a special exception, if you link this library with files |
| compiled with GCC to produce an executable, this does not cause |
| the resulting executable to be covered by the GNU General Public License. |
| This exception does not however invalidate any other reasons why |
| the executable file might be covered by the GNU General Public License. */ |
| |
| /* This file is a bit like libgcc1.c/libgcc2.c in that it is compiled |
| multiple times and yields multiple .o files. |
| |
| This file is useful on target machines where the object file format |
| supports multiple "user-defined" sections (e.g. COFF, ELF, ROSE). On |
| such systems, this file allows us to avoid running collect (or any |
| other such slow and painful kludge). Additionally, if the target |
| system supports a .init section, this file allows us to support the |
| linking of C++ code with a non-C++ main program. |
| |
| Note that if INIT_SECTION_ASM_OP is defined in the tm.h file, then |
| this file *will* make use of the .init section. If that symbol is |
| not defined however, then the .init section will not be used. |
| |
| Currently, only ELF and COFF are supported. It is likely however that |
| ROSE could also be supported, if someone was willing to do the work to |
| make whatever (small?) adaptations are needed. (Some work may be |
| needed on the ROSE assembler and linker also.) |
| |
| This file must be compiled with gcc. */ |
| |
| /* It is incorrect to include config.h here, because this file is being |
| compiled for the target, and hence definitions concerning only the host |
| do not apply. */ |
| |
| #include "tm.h" |
| #include "defaults.h" |
| #include <stddef.h> |
| #include "frame.h" |
| |
| /* We do not want to add the weak attribute to the declarations of these |
| routines in frame.h because that will cause the definition of these |
| symbols to be weak as well. |
| |
| This exposes a core issue, how to handle creating weak references vs |
| how to create weak definitions. Either we have to have the definition |
| of TARGET_WEAK_ATTRIBUTE be conditional in the shared header files or |
| have a second declaration if we want a function's references to be weak, |
| but not its definition. |
| |
| Making TARGET_WEAK_ATTRIBUTE conditional seems like a good solution until |
| one thinks about scaling to larger problems -- ie, the condition under |
| which TARGET_WEAK_ATTRIBUTE is active will eventually get far too |
| complicated. |
| |
| So, we take an approach similar to #pragma weak -- we have a second |
| declaration for functions that we want to have weak references. |
| |
| Neither way is particularly good. */ |
| |
| /* References to __register_frame_info and __deregister_frame_info should |
| be weak in this file if at all possible. */ |
| extern void __register_frame_info (void *, struct object *) |
| TARGET_ATTRIBUTE_WEAK; |
| |
| extern void *__deregister_frame_info (void *) |
| TARGET_ATTRIBUTE_WEAK; |
| |
| #ifndef OBJECT_FORMAT_MACHO |
| |
| /* Provide default definitions for the pseudo-ops used to switch to the |
| .ctors and .dtors sections. |
| |
| Note that we want to give these sections the SHF_WRITE attribute |
| because these sections will actually contain data (i.e. tables of |
| addresses of functions in the current root executable or shared library |
| file) and, in the case of a shared library, the relocatable addresses |
| will have to be properly resolved/relocated (and then written into) by |
| the dynamic linker when it actually attaches the given shared library |
| to the executing process. (Note that on SVR4, you may wish to use the |
| `-z text' option to the ELF linker, when building a shared library, as |
| an additional check that you are doing everything right. But if you do |
| use the `-z text' option when building a shared library, you will get |
| errors unless the .ctors and .dtors sections are marked as writable |
| via the SHF_WRITE attribute.) */ |
| |
| #ifndef CTORS_SECTION_ASM_OP |
| #define CTORS_SECTION_ASM_OP ".section\t.ctors,\"aw\"" |
| #endif |
| #ifndef DTORS_SECTION_ASM_OP |
| #define DTORS_SECTION_ASM_OP ".section\t.dtors,\"aw\"" |
| #endif |
| #if !defined (EH_FRAME_SECTION_ASM_OP) && defined (DWARF2_UNWIND_INFO) && defined(ASM_OUTPUT_SECTION_NAME) |
| #define EH_FRAME_SECTION_ASM_OP ".section\t.eh_frame,\"aw\"" |
| #endif |
| |
| #ifdef OBJECT_FORMAT_ELF |
| |
| /* Declare a pointer to void function type. */ |
| typedef void (*func_ptr) (void); |
| #define STATIC static |
| |
| #else /* OBJECT_FORMAT_ELF */ |
| |
| #include "gbl-ctors.h" |
| |
| #ifndef ON_EXIT |
| #define ON_EXIT(a, b) |
| #endif |
| #define STATIC |
| |
| #endif /* OBJECT_FORMAT_ELF */ |
| |
| #ifdef CRT_BEGIN |
| |
| #ifdef INIT_SECTION_ASM_OP |
| |
| #ifdef OBJECT_FORMAT_ELF |
| |
| /* Run all the global destructors on exit from the program. */ |
| |
| /* Some systems place the number of pointers in the first word of the |
| table. On SVR4 however, that word is -1. In all cases, the table is |
| null-terminated. On SVR4, we start from the beginning of the list and |
| invoke each per-compilation-unit destructor routine in order |
| until we find that null. |
| |
| Note that this function MUST be static. There will be one of these |
| functions in each root executable and one in each shared library, but |
| although they all have the same code, each one is unique in that it |
| refers to one particular associated `__DTOR_LIST__' which belongs to the |
| same particular root executable or shared library file. |
| |
| On some systems, this routine is run more than once from the .fini, |
| when exit is called recursively, so we arrange to remember where in |
| the list we left off processing, and we resume at that point, |
| should we be re-invoked. */ |
| |
| static char __EH_FRAME_BEGIN__[]; |
| static func_ptr __DTOR_LIST__[]; |
| static void |
| __do_global_dtors_aux (void) |
| { |
| static func_ptr *p = __DTOR_LIST__ + 1; |
| static int completed = 0; |
| |
| if (completed) |
| return; |
| |
| while (*p) |
| { |
| p++; |
| (*(p-1)) (); |
| } |
| |
| #ifdef EH_FRAME_SECTION_ASM_OP |
| if (__deregister_frame_info) |
| __deregister_frame_info (__EH_FRAME_BEGIN__); |
| #endif |
| completed = 1; |
| } |
| |
| |
| /* Stick a call to __do_global_dtors_aux into the .fini section. */ |
| |
| static void __attribute__ ((__unused__)) |
| fini_dummy (void) |
| { |
| asm (FINI_SECTION_ASM_OP); |
| __do_global_dtors_aux (); |
| #ifdef FORCE_FINI_SECTION_ALIGN |
| FORCE_FINI_SECTION_ALIGN; |
| #endif |
| asm (TEXT_SECTION_ASM_OP); |
| } |
| |
| #ifdef EH_FRAME_SECTION_ASM_OP |
| /* Stick a call to __register_frame_info into the .init section. For some |
| reason calls with no arguments work more reliably in .init, so stick the |
| call in another function. */ |
| |
| static void |
| frame_dummy (void) |
| { |
| static struct object object; |
| if (__register_frame_info) |
| __register_frame_info (__EH_FRAME_BEGIN__, &object); |
| } |
| |
| static void __attribute__ ((__unused__)) |
| init_dummy (void) |
| { |
| asm (INIT_SECTION_ASM_OP); |
| frame_dummy (); |
| #ifdef FORCE_INIT_SECTION_ALIGN |
| FORCE_INIT_SECTION_ALIGN; |
| #endif |
| asm (TEXT_SECTION_ASM_OP); |
| } |
| #endif /* EH_FRAME_SECTION_ASM_OP */ |
| |
| #else /* OBJECT_FORMAT_ELF */ |
| |
| /* The function __do_global_ctors_aux is compiled twice (once in crtbegin.o |
| and once in crtend.o). It must be declared static to avoid a link |
| error. Here, we define __do_global_ctors as an externally callable |
| function. It is externally callable so that __main can invoke it when |
| INVOKE__main is defined. This has the additional effect of forcing cc1 |
| to switch to the .text section. */ |
| |
| static void __do_global_ctors_aux (); |
| void |
| __do_global_ctors (void) |
| { |
| #ifdef INVOKE__main /* If __main won't actually call __do_global_ctors |
| then it doesn't matter what's inside the function. |
| The inside of __do_global_ctors_aux is called |
| automatically in that case. |
| And the Alliant fx2800 linker crashes |
| on this reference. So prevent the crash. */ |
| __do_global_ctors_aux (); |
| #endif |
| } |
| |
| asm (INIT_SECTION_ASM_OP); /* cc1 doesn't know that we are switching! */ |
| |
| /* On some svr4 systems, the initial .init section preamble code provided in |
| crti.o may do something, such as bump the stack, which we have to |
| undo before we reach the function prologue code for __do_global_ctors |
| (directly below). For such systems, define the macro INIT_SECTION_PREAMBLE |
| to expand into the code needed to undo the actions of the crti.o file. */ |
| |
| #ifdef INIT_SECTION_PREAMBLE |
| INIT_SECTION_PREAMBLE; |
| #endif |
| |
| /* A routine to invoke all of the global constructors upon entry to the |
| program. We put this into the .init section (for systems that have |
| such a thing) so that we can properly perform the construction of |
| file-scope static-storage C++ objects within shared libraries. */ |
| |
| static void |
| __do_global_ctors_aux (void) /* prologue goes in .init section */ |
| { |
| #ifdef FORCE_INIT_SECTION_ALIGN |
| FORCE_INIT_SECTION_ALIGN; /* Explicit align before switch to .text */ |
| #endif |
| asm (TEXT_SECTION_ASM_OP); /* don't put epilogue and body in .init */ |
| DO_GLOBAL_CTORS_BODY; |
| ON_EXIT (__do_global_dtors, 0); |
| } |
| |
| #endif /* OBJECT_FORMAT_ELF */ |
| |
| #else /* defined(INIT_SECTION_ASM_OP) */ |
| |
| #ifdef HAS_INIT_SECTION |
| /* This case is used by the Irix 6 port, which supports named sections but |
| not an SVR4-style .fini section. __do_global_dtors can be non-static |
| in this case because we protect it with -hidden_symbol. */ |
| |
| static char __EH_FRAME_BEGIN__[]; |
| static func_ptr __DTOR_LIST__[]; |
| void |
| __do_global_dtors (void) |
| { |
| func_ptr *p; |
| for (p = __DTOR_LIST__ + 1; *p; p++) |
| (*p) (); |
| |
| #ifdef EH_FRAME_SECTION_ASM_OP |
| if (__deregister_frame_info) |
| __deregister_frame_info (__EH_FRAME_BEGIN__); |
| #endif |
| } |
| |
| #ifdef EH_FRAME_SECTION_ASM_OP |
| /* Define a function here to call __register_frame. crtend.o is linked in |
| after libgcc.a, and hence can't call libgcc.a functions directly. That |
| can lead to unresolved function references. */ |
| void |
| __frame_dummy (void) |
| { |
| static struct object object; |
| if (__register_frame_info) |
| __register_frame_info (__EH_FRAME_BEGIN__, &object); |
| } |
| #endif |
| #endif |
| |
| #endif /* defined(INIT_SECTION_ASM_OP) */ |
| |
| /* Force cc1 to switch to .data section. */ |
| static func_ptr force_to_data[0] __attribute__ ((__unused__)) = { }; |
| |
| /* NOTE: In order to be able to support SVR4 shared libraries, we arrange |
| to have one set of symbols { __CTOR_LIST__, __DTOR_LIST__, __CTOR_END__, |
| __DTOR_END__ } per root executable and also one set of these symbols |
| per shared library. So in any given whole process image, we may have |
| multiple definitions of each of these symbols. In order to prevent |
| these definitions from conflicting with one another, and in order to |
| ensure that the proper lists are used for the initialization/finalization |
| of each individual shared library (respectively), we give these symbols |
| only internal (i.e. `static') linkage, and we also make it a point to |
| refer to only the __CTOR_END__ symbol in crtend.o and the __DTOR_LIST__ |
| symbol in crtbegin.o, where they are defined. */ |
| |
| /* The -1 is a flag to __do_global_[cd]tors |
| indicating that this table does not start with a count of elements. */ |
| #ifdef CTOR_LIST_BEGIN |
| CTOR_LIST_BEGIN; |
| #else |
| asm (CTORS_SECTION_ASM_OP); /* cc1 doesn't know that we are switching! */ |
| STATIC func_ptr __CTOR_LIST__[1] __attribute__ ((__unused__)) |
| = { (func_ptr) (-1) }; |
| #endif |
| |
| #ifdef DTOR_LIST_BEGIN |
| DTOR_LIST_BEGIN; |
| #else |
| asm (DTORS_SECTION_ASM_OP); /* cc1 doesn't know that we are switching! */ |
| STATIC func_ptr __DTOR_LIST__[1] = { (func_ptr) (-1) }; |
| #endif |
| |
| #ifdef EH_FRAME_SECTION_ASM_OP |
| /* Stick a label at the beginning of the frame unwind info so we can register |
| and deregister it with the exception handling library code. */ |
| |
| asm (EH_FRAME_SECTION_ASM_OP); |
| #ifdef INIT_SECTION_ASM_OP |
| STATIC |
| #endif |
| char __EH_FRAME_BEGIN__[] = { }; |
| #endif /* EH_FRAME_SECTION_ASM_OP */ |
| |
| #endif /* defined(CRT_BEGIN) */ |
| |
| #ifdef CRT_END |
| |
| #ifdef INIT_SECTION_ASM_OP |
| |
| #ifdef OBJECT_FORMAT_ELF |
| |
| static func_ptr __CTOR_END__[]; |
| static void |
| __do_global_ctors_aux (void) |
| { |
| func_ptr *p; |
| for (p = __CTOR_END__ - 1; *p != (func_ptr) -1; p--) |
| (*p) (); |
| } |
| |
| /* Stick a call to __do_global_ctors_aux into the .init section. */ |
| |
| static void __attribute__ ((__unused__)) |
| init_dummy (void) |
| { |
| asm (INIT_SECTION_ASM_OP); |
| __do_global_ctors_aux (); |
| #ifdef FORCE_INIT_SECTION_ALIGN |
| FORCE_INIT_SECTION_ALIGN; |
| #endif |
| asm (TEXT_SECTION_ASM_OP); |
| |
| /* This is a kludge. The i386 GNU/Linux dynamic linker needs ___brk_addr, |
| __environ and atexit (). We have to make sure they are in the .dynsym |
| section. We accomplish it by making a dummy call here. This |
| code is never reached. */ |
| |
| #if defined(__linux__) && defined(__PIC__) && defined(__i386__) |
| { |
| extern void *___brk_addr; |
| extern char **__environ; |
| |
| ___brk_addr = __environ; |
| atexit (); |
| } |
| #endif |
| } |
| |
| #else /* OBJECT_FORMAT_ELF */ |
| |
| /* Stick the real initialization code, followed by a normal sort of |
| function epilogue at the very end of the .init section for this |
| entire root executable file or for this entire shared library file. |
| |
| Note that we use some tricks here to get *just* the body and just |
| a function epilogue (but no function prologue) into the .init |
| section of the crtend.o file. Specifically, we switch to the .text |
| section, start to define a function, and then we switch to the .init |
| section just before the body code. |
| |
| Earlier on, we put the corresponding function prologue into the .init |
| section of the crtbegin.o file (which will be linked in first). |
| |
| Note that we want to invoke all constructors for C++ file-scope static- |
| storage objects AFTER any other possible initialization actions which |
| may be performed by the code in the .init section contributions made by |
| other libraries, etc. That's because those other initializations may |
| include setup operations for very primitive things (e.g. initializing |
| the state of the floating-point coprocessor, etc.) which should be done |
| before we start to execute any of the user's code. */ |
| |
| static void |
| __do_global_ctors_aux (void) /* prologue goes in .text section */ |
| { |
| asm (INIT_SECTION_ASM_OP); |
| DO_GLOBAL_CTORS_BODY; |
| ON_EXIT (__do_global_dtors, 0); |
| } /* epilogue and body go in .init section */ |
| |
| #ifdef FORCE_INIT_SECTION_ALIGN |
| FORCE_INIT_SECTION_ALIGN; |
| #endif |
| |
| asm (TEXT_SECTION_ASM_OP); |
| |
| #endif /* OBJECT_FORMAT_ELF */ |
| |
| #else /* defined(INIT_SECTION_ASM_OP) */ |
| |
| #ifdef HAS_INIT_SECTION |
| /* This case is used by the Irix 6 port, which supports named sections but |
| not an SVR4-style .init section. __do_global_ctors can be non-static |
| in this case because we protect it with -hidden_symbol. */ |
| static func_ptr __CTOR_END__[]; |
| #ifdef EH_FRAME_SECTION_ASM_OP |
| extern void __frame_dummy (void); |
| #endif |
| void |
| __do_global_ctors (void) |
| { |
| func_ptr *p; |
| #ifdef EH_FRAME_SECTION_ASM_OP |
| __frame_dummy (); |
| #endif |
| for (p = __CTOR_END__ - 1; *p != (func_ptr) -1; p--) |
| (*p) (); |
| } |
| #endif |
| |
| #endif /* defined(INIT_SECTION_ASM_OP) */ |
| |
| /* Force cc1 to switch to .data section. */ |
| static func_ptr force_to_data[0] __attribute__ ((__unused__)) = { }; |
| |
| /* Put a word containing zero at the end of each of our two lists of function |
| addresses. Note that the words defined here go into the .ctors and .dtors |
| sections of the crtend.o file, and since that file is always linked in |
| last, these words naturally end up at the very ends of the two lists |
| contained in these two sections. */ |
| |
| #ifdef CTOR_LIST_END |
| CTOR_LIST_END; |
| #else |
| asm (CTORS_SECTION_ASM_OP); /* cc1 doesn't know that we are switching! */ |
| STATIC func_ptr __CTOR_END__[1] = { (func_ptr) 0 }; |
| #endif |
| |
| #ifdef DTOR_LIST_END |
| DTOR_LIST_END; |
| #else |
| asm (DTORS_SECTION_ASM_OP); /* cc1 doesn't know that we are switching! */ |
| STATIC func_ptr __DTOR_END__[1] __attribute__ ((__unused__)) |
| = { (func_ptr) 0 }; |
| #endif |
| |
| #ifdef EH_FRAME_SECTION_ASM_OP |
| /* Terminate the frame unwind info section with a 4byte 0 as a sentinel; |
| this would be the 'length' field in a real FDE. */ |
| |
| typedef unsigned int ui32 __attribute__ ((mode (SI))); |
| asm (EH_FRAME_SECTION_ASM_OP); |
| STATIC ui32 __FRAME_END__[] __attribute__ ((__unused__)) = { 0 }; |
| #endif /* EH_FRAME_SECTION */ |
| |
| #endif /* defined(CRT_END) */ |
| |
| #else /* OBJECT_FORMAT_MACHO */ |
| |
| /* For Mach-O format executables, we assume that the system's runtime is |
| smart enough to handle constructors and destructors, but doesn't have |
| an init section (if it can't even handle constructors/destructors |
| you should be using INVOKE__main, not crtstuff). All we need to do |
| is install/deinstall the frame information for exceptions. We do this |
| by putting a constructor in crtbegin.o and a destructor in crtend.o. |
| |
| crtend.o also puts in the terminating zero in the frame information |
| segment. */ |
| |
| /* The crtstuff for other object formats use the symbol __EH_FRAME_BEGIN__ |
| to figure out the start of the exception frame, but here we use |
| getsectbynamefromheader to find this value. Either method would work, |
| but this method avoids creating any global symbols, which seems |
| cleaner. */ |
| |
| #include <mach-o/ldsyms.h> |
| extern const struct section * |
| getsectbynamefromheader (const struct mach_header *, |
| const char *, const char *); |
| |
| #ifdef CRT_BEGIN |
| |
| static void __reg_frame_ctor () __attribute__ ((constructor)); |
| |
| static void |
| __reg_frame_ctor (void) |
| { |
| static struct object object; |
| const struct section *eh_frame; |
| |
| eh_frame = getsectbynamefromheader (&_mh_execute_header, |
| "__TEXT", "__eh_frame"); |
| __register_frame_info ((void *) eh_frame->addr, &object); |
| } |
| |
| #endif /* CRT_BEGIN */ |
| |
| #ifdef CRT_END |
| |
| static void __dereg_frame_dtor () __attribute__ ((destructor)); |
| |
| static |
| void |
| __dereg_frame_dtor (void) |
| { |
| const struct section *eh_frame; |
| |
| eh_frame = getsectbynamefromheader (&_mh_execute_header, |
| "__TEXT", "__eh_frame"); |
| __deregister_frame_info ((void *) eh_frame->addr); |
| } |
| |
| /* Terminate the frame section with a final zero. */ |
| |
| /* Force cc1 to switch to .data section. */ |
| static void * force_to_data[0] __attribute__ ((__unused__)) = { }; |
| |
| typedef unsigned int ui32 __attribute__ ((mode (SI))); |
| asm (EH_FRAME_SECTION_ASM_OP); |
| static ui32 __FRAME_END__[] __attribute__ ((__unused__)) = { 0 }; |
| |
| #endif /* CRT_END */ |
| |
| #endif /* OBJECT_FORMAT_MACHO */ |
| |