1/* Specialized bits of code needed to support construction and 2 destruction of file-scope objects in C++ code. 3 Copyright (C) 1991, 1994, 1995, 1996, 1997, 1998, 4 1999, 2000, 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc. 5 Contributed by Ron Guilmette (rfg@monkeys.com). 6 7This file is part of GCC. 8 9GCC is free software; you can redistribute it and/or modify it under 10the terms of the GNU General Public License as published by the Free 11Software Foundation; either version 2, or (at your option) any later 12version. 13 14In addition to the permissions in the GNU General Public License, the 15Free Software Foundation gives you unlimited permission to link the 16compiled version of this file into combinations with other programs, 17and to distribute those combinations without any restriction coming 18from the use of this file. (The General Public License restrictions 19do apply in other respects; for example, they cover modification of 20the file, and distribution when not linked into a combine 21executable.) 22 23GCC is distributed in the hope that it will be useful, but WITHOUT ANY 24WARRANTY; without even the implied warranty of MERCHANTABILITY or 25FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 26for more details. 27 28You should have received a copy of the GNU General Public License 29along with GCC; see the file COPYING. If not, write to the Free 30Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 3102110-1301, USA. */ 32 33/* This file is a bit like libgcc2.c in that it is compiled 34 multiple times and yields multiple .o files. 35 36 This file is useful on target machines where the object file format 37 supports multiple "user-defined" sections (e.g. COFF, ELF, ROSE). On 38 such systems, this file allows us to avoid running collect (or any 39 other such slow and painful kludge). Additionally, if the target 40 system supports a .init section, this file allows us to support the 41 linking of C++ code with a non-C++ main program. 42 43 Note that if INIT_SECTION_ASM_OP is defined in the tm.h file, then 44 this file *will* make use of the .init section. If that symbol is 45 not defined however, then the .init section will not be used. 46 47 Currently, only ELF and COFF are supported. It is likely however that 48 ROSE could also be supported, if someone was willing to do the work to 49 make whatever (small?) adaptations are needed. (Some work may be 50 needed on the ROSE assembler and linker also.) 51 52 This file must be compiled with gcc. */ 53 54/* Target machine header files require this define. */ 55#define IN_LIBGCC2 56 57/* FIXME: Including auto-host is incorrect, but until we have 58 identified the set of defines that need to go into auto-target.h, 59 this will have to do. */ 60#include "auto-host.h" 61#undef gid_t 62#undef pid_t 63#undef rlim_t 64#undef ssize_t 65#undef uid_t 66#undef vfork 67#include "tconfig.h" 68#include "tsystem.h" 69#include "coretypes.h" 70#include "tm.h" 71#include "unwind-dw2-fde.h" 72 73#ifndef FORCE_CODE_SECTION_ALIGN 74# define FORCE_CODE_SECTION_ALIGN 75#endif 76 77#ifndef CRT_CALL_STATIC_FUNCTION 78# define CRT_CALL_STATIC_FUNCTION(SECTION_OP, FUNC) \ 79static void __attribute__((__used__)) \ 80call_ ## FUNC (void) \ 81{ \ 82 asm (SECTION_OP); \ 83 FUNC (); \ 84 FORCE_CODE_SECTION_ALIGN \ 85 asm (TEXT_SECTION_ASM_OP); \ 86} 87#endif 88 89#if defined(OBJECT_FORMAT_ELF) && defined(HAVE_LD_EH_FRAME_HDR) \ 90 && !defined(inhibit_libc) && !defined(CRTSTUFFT_O) \ 91 && defined(__GLIBC__) && __GLIBC__ >= 2 92#include <link.h> 93# if (__GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ > 2) \ 94 || (__GLIBC__ == 2 && __GLIBC_MINOR__ == 2 && defined(DT_CONFIG))) 95# define USE_PT_GNU_EH_FRAME 96# endif 97#endif 98#if defined(EH_FRAME_SECTION_NAME) && !defined(USE_PT_GNU_EH_FRAME) 99# define USE_EH_FRAME_REGISTRY 100#endif 101#if defined(EH_FRAME_SECTION_NAME) && EH_TABLES_CAN_BE_READ_ONLY 102# define EH_FRAME_SECTION_CONST const 103#else 104# define EH_FRAME_SECTION_CONST 105#endif 106 107/* We do not want to add the weak attribute to the declarations of these 108 routines in unwind-dw2-fde.h because that will cause the definition of 109 these symbols to be weak as well. 110 111 This exposes a core issue, how to handle creating weak references vs 112 how to create weak definitions. Either we have to have the definition 113 of TARGET_WEAK_ATTRIBUTE be conditional in the shared header files or 114 have a second declaration if we want a function's references to be weak, 115 but not its definition. 116 117 Making TARGET_WEAK_ATTRIBUTE conditional seems like a good solution until 118 one thinks about scaling to larger problems -- i.e., the condition under 119 which TARGET_WEAK_ATTRIBUTE is active will eventually get far too 120 complicated. 121 122 So, we take an approach similar to #pragma weak -- we have a second 123 declaration for functions that we want to have weak references. 124 125 Neither way is particularly good. */ 126 127/* References to __register_frame_info and __deregister_frame_info should 128 be weak in this file if at all possible. */ 129extern void __register_frame_info (const void *, struct object *) 130 TARGET_ATTRIBUTE_WEAK; 131extern void __register_frame_info_bases (const void *, struct object *, 132 void *, void *) 133 TARGET_ATTRIBUTE_WEAK; 134extern void *__deregister_frame_info (const void *) 135 TARGET_ATTRIBUTE_WEAK; 136extern void *__deregister_frame_info_bases (const void *) 137 TARGET_ATTRIBUTE_WEAK; 138extern void __do_global_ctors_1 (void); 139 140/* Likewise for _Jv_RegisterClasses. */ 141extern void _Jv_RegisterClasses (void *) TARGET_ATTRIBUTE_WEAK; 142 143#ifdef OBJECT_FORMAT_ELF 144 145/* Declare a pointer to void function type. */ 146typedef void (*func_ptr) (void); 147#define STATIC static 148 149#else /* OBJECT_FORMAT_ELF */ 150 151#include "gbl-ctors.h" 152 153#define STATIC 154 155#endif /* OBJECT_FORMAT_ELF */ 156 157#ifdef CRT_BEGIN 158 159/* NOTE: In order to be able to support SVR4 shared libraries, we arrange 160 to have one set of symbols { __CTOR_LIST__, __DTOR_LIST__, __CTOR_END__, 161 __DTOR_END__ } per root executable and also one set of these symbols 162 per shared library. So in any given whole process image, we may have 163 multiple definitions of each of these symbols. In order to prevent 164 these definitions from conflicting with one another, and in order to 165 ensure that the proper lists are used for the initialization/finalization 166 of each individual shared library (respectively), we give these symbols 167 only internal (i.e. `static') linkage, and we also make it a point to 168 refer to only the __CTOR_END__ symbol in crtend.o and the __DTOR_LIST__ 169 symbol in crtbegin.o, where they are defined. */ 170 171/* The -1 is a flag to __do_global_[cd]tors indicating that this table 172 does not start with a count of elements. */ 173#ifdef CTOR_LIST_BEGIN 174CTOR_LIST_BEGIN; 175#elif defined(CTORS_SECTION_ASM_OP) 176/* Hack: force cc1 to switch to .data section early, so that assembling 177 __CTOR_LIST__ does not undo our behind-the-back change to .ctors. */ 178static func_ptr force_to_data[1] __attribute__ ((__used__)) = { }; 179asm (CTORS_SECTION_ASM_OP); 180STATIC func_ptr __CTOR_LIST__[1] 181 __attribute__ ((__used__, aligned(sizeof(func_ptr)))) 182 = { (func_ptr) (-1) }; 183#else 184STATIC func_ptr __CTOR_LIST__[1] 185 __attribute__ ((__used__, section(".ctors"), aligned(sizeof(func_ptr)))) 186 = { (func_ptr) (-1) }; 187#endif /* __CTOR_LIST__ alternatives */ 188 189#ifdef DTOR_LIST_BEGIN 190DTOR_LIST_BEGIN; 191#elif defined(DTORS_SECTION_ASM_OP) 192asm (DTORS_SECTION_ASM_OP); 193STATIC func_ptr __DTOR_LIST__[1] 194 __attribute__ ((used, aligned(sizeof(func_ptr)))) 195 = { (func_ptr) (-1) }; 196#else 197STATIC func_ptr __DTOR_LIST__[1] 198 __attribute__((used, section(".dtors"), aligned(sizeof(func_ptr)))) 199 = { (func_ptr) (-1) }; 200#endif /* __DTOR_LIST__ alternatives */ 201 202#ifdef USE_EH_FRAME_REGISTRY 203/* Stick a label at the beginning of the frame unwind info so we can register 204 and deregister it with the exception handling library code. */ 205STATIC EH_FRAME_SECTION_CONST char __EH_FRAME_BEGIN__[] 206 __attribute__((used, section(EH_FRAME_SECTION_NAME), aligned(4))) 207 = { }; 208#endif /* USE_EH_FRAME_REGISTRY */ 209 210#ifdef JCR_SECTION_NAME 211/* Stick a label at the beginning of the java class registration info 212 so we can register them properly. */ 213STATIC void *__JCR_LIST__[] 214 __attribute__ ((used, section(JCR_SECTION_NAME), aligned(sizeof(void*)))) 215 = { }; 216#endif /* JCR_SECTION_NAME */ 217 218#if defined(INIT_SECTION_ASM_OP) || defined(INIT_ARRAY_SECTION_ASM_OP) 219 220#ifdef OBJECT_FORMAT_ELF 221 222/* Declare the __dso_handle variable. It should have a unique value 223 in every shared-object; in a main program its value is zero. The 224 object should in any case be protected. This means the instance 225 in one DSO or the main program is not used in another object. The 226 dynamic linker takes care of this. */ 227 228#ifdef TARGET_LIBGCC_SDATA_SECTION 229extern void *__dso_handle __attribute__ ((__section__ (TARGET_LIBGCC_SDATA_SECTION))); 230#endif 231#ifdef HAVE_GAS_HIDDEN 232extern void *__dso_handle __attribute__ ((__visibility__ ("hidden"))); 233#endif 234#ifdef CRTSTUFFS_O 235void *__dso_handle = &__dso_handle; 236#else 237void *__dso_handle = 0; 238#endif 239 240/* The __cxa_finalize function may not be available so we use only a 241 weak declaration. */ 242extern void __cxa_finalize (void *) TARGET_ATTRIBUTE_WEAK; 243 244/* Run all the global destructors on exit from the program. */ 245 246/* Some systems place the number of pointers in the first word of the 247 table. On SVR4 however, that word is -1. In all cases, the table is 248 null-terminated. On SVR4, we start from the beginning of the list and 249 invoke each per-compilation-unit destructor routine in order 250 until we find that null. 251 252 Note that this function MUST be static. There will be one of these 253 functions in each root executable and one in each shared library, but 254 although they all have the same code, each one is unique in that it 255 refers to one particular associated `__DTOR_LIST__' which belongs to the 256 same particular root executable or shared library file. 257 258 On some systems, this routine is run more than once from the .fini, 259 when exit is called recursively, so we arrange to remember where in 260 the list we left off processing, and we resume at that point, 261 should we be re-invoked. */ 262 263static void __attribute__((used)) 264__do_global_dtors_aux (void) 265{ 266#ifndef FINI_ARRAY_SECTION_ASM_OP 267 static func_ptr *p = __DTOR_LIST__ + 1; 268 func_ptr f; 269#endif /* !defined(FINI_ARRAY_SECTION_ASM_OP) */ 270 static _Bool completed; 271 272 if (__builtin_expect (completed, 0)) 273 return; 274 275#ifdef CRTSTUFFS_O 276 if (__cxa_finalize) 277 __cxa_finalize (__dso_handle); 278#endif 279 280#ifdef FINI_ARRAY_SECTION_ASM_OP 281 /* If we are using .fini_array then destructors will be run via that 282 mechanism. */ 283#else /* !defined (FINI_ARRAY_SECTION_ASM_OP) */ 284 while ((f = *p)) 285 { 286 p++; 287 f (); 288 } 289#endif /* !defined(FINI_ARRAY_SECTION_ASM_OP) */ 290 291#ifdef USE_EH_FRAME_REGISTRY 292#ifdef CRT_GET_RFIB_DATA 293 /* If we used the new __register_frame_info_bases interface, 294 make sure that we deregister from the same place. */ 295 if (__deregister_frame_info_bases) 296 __deregister_frame_info_bases (__EH_FRAME_BEGIN__); 297#else 298 if (__deregister_frame_info) 299 __deregister_frame_info (__EH_FRAME_BEGIN__); 300#endif 301#endif 302 303 completed = 1; 304} 305 306/* Stick a call to __do_global_dtors_aux into the .fini section. */ 307#ifdef FINI_SECTION_ASM_OP 308CRT_CALL_STATIC_FUNCTION (FINI_SECTION_ASM_OP, __do_global_dtors_aux) 309#else /* !defined(FINI_SECTION_ASM_OP) */ 310static func_ptr __do_global_dtors_aux_fini_array_entry[] 311 __attribute__ ((__used__, section(".fini_array"))) 312 = { __do_global_dtors_aux }; 313#endif /* !defined(FINI_SECTION_ASM_OP) */ 314 315#if defined(USE_EH_FRAME_REGISTRY) || defined(JCR_SECTION_NAME) 316/* Stick a call to __register_frame_info into the .init section. For some 317 reason calls with no arguments work more reliably in .init, so stick the 318 call in another function. */ 319 320static void __attribute__((used)) 321frame_dummy (void) 322{ 323#ifdef USE_EH_FRAME_REGISTRY 324 static struct object object; 325#ifdef CRT_GET_RFIB_DATA 326 void *tbase, *dbase; 327 tbase = 0; 328 CRT_GET_RFIB_DATA (dbase); 329 if (__register_frame_info_bases) 330 __register_frame_info_bases (__EH_FRAME_BEGIN__, &object, tbase, dbase); 331#else 332 if (__register_frame_info) 333 __register_frame_info (__EH_FRAME_BEGIN__, &object); 334#endif /* CRT_GET_RFIB_DATA */ 335#endif /* USE_EH_FRAME_REGISTRY */ 336#ifdef JCR_SECTION_NAME 337 if (__JCR_LIST__[0]) 338 { 339 void (*register_classes) (void *) = _Jv_RegisterClasses; 340 __asm ("" : "+r" (register_classes)); 341 if (register_classes) 342 register_classes (__JCR_LIST__); 343 } 344#endif /* JCR_SECTION_NAME */ 345} 346 347#ifdef INIT_SECTION_ASM_OP 348CRT_CALL_STATIC_FUNCTION (INIT_SECTION_ASM_OP, frame_dummy) 349#else /* defined(INIT_SECTION_ASM_OP) */ 350static func_ptr __frame_dummy_init_array_entry[] 351 __attribute__ ((__used__, section(".init_array"))) 352 = { frame_dummy }; 353#endif /* !defined(INIT_SECTION_ASM_OP) */ 354#endif /* USE_EH_FRAME_REGISTRY || JCR_SECTION_NAME */ 355 356#else /* OBJECT_FORMAT_ELF */ 357 358/* The function __do_global_ctors_aux is compiled twice (once in crtbegin.o 359 and once in crtend.o). It must be declared static to avoid a link 360 error. Here, we define __do_global_ctors as an externally callable 361 function. It is externally callable so that __main can invoke it when 362 INVOKE__main is defined. This has the additional effect of forcing cc1 363 to switch to the .text section. */ 364 365static void __do_global_ctors_aux (void); 366void 367__do_global_ctors (void) 368{ 369#ifdef INVOKE__main 370 /* If __main won't actually call __do_global_ctors then it doesn't matter 371 what's inside the function. The inside of __do_global_ctors_aux is 372 called automatically in that case. And the Alliant fx2800 linker 373 crashes on this reference. So prevent the crash. */ 374 __do_global_ctors_aux (); 375#endif 376} 377 378asm (INIT_SECTION_ASM_OP); /* cc1 doesn't know that we are switching! */ 379 380/* A routine to invoke all of the global constructors upon entry to the 381 program. We put this into the .init section (for systems that have 382 such a thing) so that we can properly perform the construction of 383 file-scope static-storage C++ objects within shared libraries. */ 384 385static void __attribute__((used)) 386__do_global_ctors_aux (void) /* prologue goes in .init section */ 387{ 388 FORCE_CODE_SECTION_ALIGN /* explicit align before switch to .text */ 389 asm (TEXT_SECTION_ASM_OP); /* don't put epilogue and body in .init */ 390 DO_GLOBAL_CTORS_BODY; 391 atexit (__do_global_dtors); 392} 393 394#endif /* OBJECT_FORMAT_ELF */ 395 396#elif defined(HAS_INIT_SECTION) /* ! INIT_SECTION_ASM_OP */ 397 398extern void __do_global_dtors (void); 399 400/* This case is used by the Irix 6 port, which supports named sections but 401 not an SVR4-style .fini section. __do_global_dtors can be non-static 402 in this case because we protect it with -hidden_symbol. */ 403 404void 405__do_global_dtors (void) 406{ 407 func_ptr *p, f; 408 for (p = __DTOR_LIST__ + 1; (f = *p); p++) 409 f (); 410 411#ifdef USE_EH_FRAME_REGISTRY 412 if (__deregister_frame_info) 413 __deregister_frame_info (__EH_FRAME_BEGIN__); 414#endif 415} 416 417#if defined(USE_EH_FRAME_REGISTRY) || defined(JCR_SECTION_NAME) 418/* A helper function for __do_global_ctors, which is in crtend.o. Here 419 in crtbegin.o, we can reference a couple of symbols not visible there. 420 Plus, since we're before libgcc.a, we have no problems referencing 421 functions from there. */ 422void 423__do_global_ctors_1(void) 424{ 425#ifdef USE_EH_FRAME_REGISTRY 426 static struct object object; 427 if (__register_frame_info) 428 __register_frame_info (__EH_FRAME_BEGIN__, &object); 429#endif 430#ifdef JCR_SECTION_NAME 431 if (__JCR_LIST__[0]) 432 { 433 void (*register_classes) (void *) = _Jv_RegisterClasses; 434 __asm ("" : "+r" (register_classes)); 435 if (register_classes) 436 register_classes (__JCR_LIST__); 437 } 438#endif 439} 440#endif /* USE_EH_FRAME_REGISTRY || JCR_SECTION_NAME */ 441 442#else /* ! INIT_SECTION_ASM_OP && ! HAS_INIT_SECTION */ 443#error "What are you doing with crtstuff.c, then?" 444#endif 445 446#elif defined(CRT_END) /* ! CRT_BEGIN */ 447 448/* Put a word containing zero at the end of each of our two lists of function 449 addresses. Note that the words defined here go into the .ctors and .dtors 450 sections of the crtend.o file, and since that file is always linked in 451 last, these words naturally end up at the very ends of the two lists 452 contained in these two sections. */ 453 454#ifdef CTOR_LIST_END 455CTOR_LIST_END; 456#elif defined(CTORS_SECTION_ASM_OP) 457/* Hack: force cc1 to switch to .data section early, so that assembling 458 __CTOR_LIST__ does not undo our behind-the-back change to .ctors. */ 459static func_ptr force_to_data[1] __attribute__ ((__used__)) = { }; 460asm (CTORS_SECTION_ASM_OP); 461STATIC func_ptr __CTOR_END__[1] 462 __attribute__((used, aligned(sizeof(func_ptr)))) 463 = { (func_ptr) 0 }; 464#else 465STATIC func_ptr __CTOR_END__[1] 466 __attribute__((used, section(".ctors"), aligned(sizeof(func_ptr)))) 467 = { (func_ptr) 0 }; 468#endif 469 470#ifdef DTOR_LIST_END 471DTOR_LIST_END; 472#elif defined(DTORS_SECTION_ASM_OP) 473asm (DTORS_SECTION_ASM_OP); 474STATIC func_ptr __DTOR_END__[1] 475 __attribute__ ((used, aligned(sizeof(func_ptr)))) 476 = { (func_ptr) 0 }; 477#else 478STATIC func_ptr __DTOR_END__[1] 479 __attribute__((used, section(".dtors"), aligned(sizeof(func_ptr)))) 480 = { (func_ptr) 0 }; 481#endif 482 483#ifdef EH_FRAME_SECTION_NAME 484/* Terminate the frame unwind info section with a 4byte 0 as a sentinel; 485 this would be the 'length' field in a real FDE. */ 486# if __INT_MAX__ == 2147483647 487typedef int int32; 488# elif __LONG_MAX__ == 2147483647 489typedef long int32; 490# elif __SHRT_MAX__ == 2147483647 491typedef short int32; 492# else 493# error "Missing a 4 byte integer" 494# endif 495STATIC EH_FRAME_SECTION_CONST int32 __FRAME_END__[] 496 __attribute__ ((used, section(EH_FRAME_SECTION_NAME), 497 aligned(sizeof(int32)))) 498 = { 0 }; 499#endif /* EH_FRAME_SECTION_NAME */ 500 501#ifdef JCR_SECTION_NAME 502/* Null terminate the .jcr section array. */ 503STATIC void *__JCR_END__[1] 504 __attribute__ ((used, section(JCR_SECTION_NAME), 505 aligned(sizeof(void *)))) 506 = { 0 }; 507#endif /* JCR_SECTION_NAME */ 508 509#ifdef INIT_ARRAY_SECTION_ASM_OP 510 511/* If we are using .init_array, there is nothing to do. */ 512 513#elif defined(INIT_SECTION_ASM_OP) 514 515#ifdef OBJECT_FORMAT_ELF 516static void __attribute__((used)) 517__do_global_ctors_aux (void) 518{ 519 func_ptr *p; 520 for (p = __CTOR_END__ - 1; *p != (func_ptr) -1; p--) 521 (*p) (); 522} 523 524/* Stick a call to __do_global_ctors_aux into the .init section. */ 525CRT_CALL_STATIC_FUNCTION (INIT_SECTION_ASM_OP, __do_global_ctors_aux) 526#else /* OBJECT_FORMAT_ELF */ 527 528/* Stick the real initialization code, followed by a normal sort of 529 function epilogue at the very end of the .init section for this 530 entire root executable file or for this entire shared library file. 531 532 Note that we use some tricks here to get *just* the body and just 533 a function epilogue (but no function prologue) into the .init 534 section of the crtend.o file. Specifically, we switch to the .text 535 section, start to define a function, and then we switch to the .init 536 section just before the body code. 537 538 Earlier on, we put the corresponding function prologue into the .init 539 section of the crtbegin.o file (which will be linked in first). 540 541 Note that we want to invoke all constructors for C++ file-scope static- 542 storage objects AFTER any other possible initialization actions which 543 may be performed by the code in the .init section contributions made by 544 other libraries, etc. That's because those other initializations may 545 include setup operations for very primitive things (e.g. initializing 546 the state of the floating-point coprocessor, etc.) which should be done 547 before we start to execute any of the user's code. */ 548 549static void 550__do_global_ctors_aux (void) /* prologue goes in .text section */ 551{ 552 asm (INIT_SECTION_ASM_OP); 553 DO_GLOBAL_CTORS_BODY; 554 atexit (__do_global_dtors); 555} /* epilogue and body go in .init section */ 556 557FORCE_CODE_SECTION_ALIGN 558asm (TEXT_SECTION_ASM_OP); 559 560#endif /* OBJECT_FORMAT_ELF */ 561 562#elif defined(HAS_INIT_SECTION) /* ! INIT_SECTION_ASM_OP */ 563 564extern void __do_global_ctors (void); 565 566/* This case is used by the Irix 6 port, which supports named sections but 567 not an SVR4-style .init section. __do_global_ctors can be non-static 568 in this case because we protect it with -hidden_symbol. */ 569void 570__do_global_ctors (void) 571{ 572 func_ptr *p; 573#if defined(USE_EH_FRAME_REGISTRY) || defined(JCR_SECTION_NAME) 574 __do_global_ctors_1(); 575#endif 576 for (p = __CTOR_END__ - 1; *p != (func_ptr) -1; p--) 577 (*p) (); 578} 579 580#else /* ! INIT_SECTION_ASM_OP && ! HAS_INIT_SECTION */ 581#error "What are you doing with crtstuff.c, then?" 582#endif 583 584#else /* ! CRT_BEGIN && ! CRT_END */ 585#error "One of CRT_BEGIN or CRT_END must be defined." 586#endif 587