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* libc-symbols.h [GCC >= 2.7] (strong_alias, weak_alias): Use extern storage class. GCC gives an error for non-extern data defns with the alias attribute. Mon Jul 8 00:11:15 1996 Roland McGrath <roland@delasyd.gnu.ai.mit.edu> * libc-symbols.h (weak_function): New macro. For GCC 2.7+ define as __attribute__ ((weak)). * elf/dl-minimal.c: Use weak_function as keyword in function defns instead of weak_symbol (NAME) after the defn. * stdlib/strtol.c: Likewise. * sysdeps/mach/hurd/dl-sysdep.c: Likewise. * sysdeps/alpha/dl-machine.h (elf_machine_rela) [RTLD_BOOTSTRAP]: If this is defined, don't declare _dl_rtld_map as weak, and don't check for MAP pointing to it. RESOLVE is always null in this case, so test with #ifdef instead of if. * libc-symbols.h (symbol_set_declare): Use weak_extern instead of weak_symbol. * csu/initfini.c (_init): Likewise. * locale/setlocale.c (DEFINE_CATEGORY): Likewise. * misc/efgcvt_r.c: Likewise. * sysdeps/alpha/dl-machine.h (elf_machine_rela): Likewise. * sysdeps/i386/dl-machine.h (elf_machine_rel): Likewise. * libc-symbols.h [ASSEMBLER] (weak_symbol): Macro removed. It was not used in any assembler code. (weak_symbol_asm): Renamed to weak_extern_asm. (weak_extern): New macro replaces weak_symbol for weak extern refs; define to weak_extern_asm for [!ASSEMBLER]. * libc-symbols.h [! ASSEMBLER] [HAVE_WEAK_SYMBOLS] (weak_symbol_asm, weak_alias_asm): New macros, renamed from weak_symbol/weak_alias; define those now as aliases. Change conditional to use __attribute__ syntax for GCC 2.7+, not 2.8+ [GCC >= 2.7] [HAVE_WEAK_SYMBOLS] (weak_symbol): Do weak_symbol_asm after GCC weak attribute decl.
306 lines
10 KiB
C
306 lines
10 KiB
C
/* Support macros for making weak and strong aliases for symbols,
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and for using symbol sets and linker warnings with GNU ld.
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Copyright (C) 1995, 1996 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Library General Public License as
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published by the Free Software Foundation; either version 2 of the
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License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with the GNU C Library; see the file COPYING.LIB. If
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not, write to the Free Software Foundation, Inc., 675 Mass Ave,
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Cambridge, MA 02139, USA. */
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#ifndef _LIBC_SYMBOLS_H
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#define _LIBC_SYMBOLS_H
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/* This file's macros are included implicitly in the compilation of every
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file in the C library by -imacros.
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We include config.h which is generated by configure.
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It should define for us the following symbols:
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* HAVE_ASM_SET_DIRECTIVE if we have `.set B, A' instead of `A = B'.
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* ASM_GLOBAL_DIRECTIVE with `.globl' or `.global'.
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* HAVE_GNU_LD if using GNU ld, with support for weak symbols in a.out,
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and for symbol set and warning messages extensions in a.out and ELF.
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* HAVE_ELF if using ELF, which supports weak symbols using `.weak'.
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* HAVE_ASM_WEAK_DIRECTIVE if we have weak symbols using `.weak'.
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* HAVE_ASM_WEAKEXT_DIRECTIVE if we have weak symbols using `.weakext'.
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*/
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/* This is defined for the compilation of all C library code. features.h
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tests this to avoid inclusion of stubs.h while compiling the library,
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before stubs.h has been generated. Some library code that is shared
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with other packages also tests this symbol to see if it is being
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compiled as part of the C library. We must define this before including
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config.h, because it makes some definitions conditional on whether libc
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itself is being compiled, or just some generator program. */
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#define _LIBC 1
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/* Enable declarations of GNU extensions, since we are compiling them. */
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#define _GNU_SOURCE 1
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#include <config.h>
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/*
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*/
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#ifndef ASSEMBLER
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/* Define the macros `_' and `N_' for conveniently marking translatable
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strings in the libc source code. */
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#define N_(msgid) msgid
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#include <libintl.h>
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extern const char _libc_intl_domainname[];
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#ifdef dgettext
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/* This is defined as an optimizing macro, so use it. */
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#define _(msgid) dgettext (_libc_intl_domainname, (msgid))
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#else
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/* Be sure to use only the __ name when `dgettext' is a plain function
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instead of an optimizing macro. */
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#define _(msgid) __dgettext (_libc_intl_domainname, (msgid))
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#endif
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#endif
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/*
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*/
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/* The symbols in all the user (non-_) macros are C symbols.
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HAVE_GNU_LD without HAVE_ELF implies a.out. */
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#if defined (HAVE_ASM_WEAK_DIRECTIVE) || defined (HAVE_ASM_WEAKEXT_DIRECTIVE)
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#define HAVE_WEAK_SYMBOLS
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#endif
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#ifndef __SYMBOL_PREFIX
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#ifdef NO_UNDERSCORES
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#define __SYMBOL_PREFIX
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#else
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#define __SYMBOL_PREFIX "_"
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#endif
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#endif
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#ifndef C_SYMBOL_NAME
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#ifdef NO_UNDERSCORES
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#define C_SYMBOL_NAME(name) name
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#else
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#define C_SYMBOL_NAME(name) _##name
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#endif
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#endif
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/* Define ALIAS as a strong alias for ORIGINAL. */
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#ifdef HAVE_ASM_SET_DIRECTIVE
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#define strong_alias_asm(original, alias) \
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ASM_GLOBAL_DIRECTIVE C_SYMBOL_NAME (alias); \
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.set C_SYMBOL_NAME (alias),C_SYMBOL_NAME (original)
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#ifdef ASSEMBLER
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#define strong_alias(original, alias) strong_alias_asm (original, alias)
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#else
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#define strong_alias(original, alias) \
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asm (__string_1 (ASM_GLOBAL_DIRECTIVE) " " __SYMBOL_PREFIX #alias "\n" \
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".set " __SYMBOL_PREFIX #alias "," __SYMBOL_PREFIX #original);
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#endif
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#else
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#define strong_alias_asm(original, alias) \
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ASM_GLOBAL_DIRECTIVE C_SYMBOL_NAME (alias); \
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C_SYMBOL_NAME (alias) = C_SYMBOL_NAME (original)
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#ifdef ASSEMBLER
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#define strong_alias(original, alias) strong_alias_asm (original, alias)
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#else
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#define strong_alias(original, alias) \
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asm (__string_1 (ASM_GLOBAL_DIRECTIVE) " " __SYMBOL_PREFIX #alias "\n" \
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__SYMBOL_PREFIX #alias " = " __SYMBOL_PREFIX #original);
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#endif
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#endif
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/* Helper macros used above. */
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#define __string_1(x) __string_0(x)
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#define __string_0(x) #x
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#ifdef HAVE_WEAK_SYMBOLS
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#ifdef ASSEMBLER
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#ifdef HAVE_ASM_WEAKEXT_DIRECTIVE
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/* Define ALIAS as a weak alias for ORIGINAL.
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If weak aliases are not available, this defines a strong alias. */
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#define weak_alias(original, alias) \
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.weakext C_SYMBOL_NAME (alias), C_SYMBOL_NAME (original)
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/* Declare SYMBOL as weak undefined symbol (resolved to 0 if not defined). */
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#define weak_extern(symbol) \
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.weakext C_SYMBOL_NAME (symbol)
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#else /* ! HAVE_ASM_WEAKEXT_DIRECTIVE */
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/* Define ALIAS as a weak alias for ORIGINAL.
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If weak aliases are not available, this defines a strong alias. */
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#define weak_alias(original, alias) \
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.weak C_SYMBOL_NAME (alias); \
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C_SYMBOL_NAME (alias) = C_SYMBOL_NAME (original)
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/* Declare SYMBOL as weak undefined symbol (resolved to 0 if not defined). */
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#define weak_extern(symbol) \
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.weak C_SYMBOL_NAME (symbol)
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#endif /* ! HAVE_ASM_WEAKEXT_DIRECTIVE */
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#else /* ! ASSEMBLER */
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#ifdef HAVE_ASM_WEAKEXT_DIRECTIVE
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#define weak_extern_asm(symbol) asm (".weakext " __SYMBOL_PREFIX #symbol);
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#define weak_alias_asm(original, alias) \
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asm (".weakext " __SYMBOL_PREFIX #alias ", " __SYMBOL_PREFIX #original);
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#else /* ! HAVE_ASM_WEAKEXT_DIRECTIVE */
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#define weak_extern_asm(symbol) asm (".weak " __SYMBOL_PREFIX #symbol);
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#define weak_alias_asm(original, alias) \
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asm (".weak " __SYMBOL_PREFIX #alias "\n" \
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__SYMBOL_PREFIX #alias " = " __SYMBOL_PREFIX #original);
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#endif /* ! HAVE_ASM_WEAKEXT_DIRECTIVE */
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#define weak_alias(o, a) weak_alias_asm (o, a)
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#define weak_extern(symbol) weak_extern_asm (symbol)
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#endif /* ! ASSEMBLER */
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#else
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#define weak_alias(original, alias) strong_alias(original, alias)
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#define weak_extern(symbol) /* Do nothing; the ref will be strong. */
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#endif
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#if (!defined (ASSEMBLER) && \
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(__GNUC__ > 2 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 7)))
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/* GCC 2.7 and later has special syntax for weak symbols and aliases.
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Using that is better when possible, because the compiler and assembler
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are better clued in to what we are doing. */
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#undef strong_alias
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#define strong_alias(name, aliasname) \
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extern __typeof (name) aliasname __attribute__ ((alias (#name)));
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#ifdef HAVE_WEAK_SYMBOLS
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#undef weak_alias
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#define weak_alias(name, aliasname) \
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extern __typeof (name) aliasname __attribute__ ((weak, alias (#name)));
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/* This comes between the return type and function name in
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a function definition to make that definition weak. */
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#define weak_function __attribute__ ((weak))
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#endif /* HAVE_WEAK_SYMBOLS. */
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#endif /* Not ASSEMBLER, and GCC 2.7 or later. */
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#ifndef weak_function
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/* If we do not have the __attribute__ ((weak)) syntax, there is no way we
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can define functions as weak symbols. The compiler will emit a `.globl'
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directive for the function symbol, and a `.weak' directive in addition
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will produce an error from the assembler. */
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#define weak_function /* empty */
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#endif
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/* When a reference to SYMBOL is encountered, the linker will emit a
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warning message MSG. */
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#ifdef HAVE_GNU_LD
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#ifdef HAVE_ELF
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#define link_warning(symbol, msg) \
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static const char __evoke_link_warning_##symbol[] \
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__attribute__ ((section (".gnu.warning." #symbol))) = msg;
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#else
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#define link_warning(symbol, msg) \
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asm(".stabs \"" msg "\",30,0,0,0\n" \
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".stabs \"" __SYMBOL_PREFIX #symbol "\",1,0,0,0\n");
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#endif
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#else
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/* We will never be heard; they will all die horribly. */
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#define link_warning(symbol, msg)
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#endif
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/* A canned warning for sysdeps/stub functions. */
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#define stub_warning(name) \
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link_warning (name, \
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"warning: " #name " is not implemented and will always fail")
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/*
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*/
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#ifdef HAVE_GNU_LD
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/* Symbol set support macros. */
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#ifdef HAVE_ELF
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/* Make SYMBOL, which is in the text segment, an element of SET. */
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#define text_set_element(set, symbol) _elf_set_element(set, symbol)
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/* Make SYMBOL, which is in the data segment, an element of SET. */
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#define data_set_element(set, symbol) _elf_set_element(set, symbol)
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/* Make SYMBOL, which is in the bss segment, an element of SET. */
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#define bss_set_element(set, symbol) _elf_set_element(set, symbol)
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/* These are all done the same way in ELF.
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There is a new section created for each set. */
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#ifdef PIC
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/* When building a shared library, make the set section writable,
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because it will need to be relocated at run time anyway. */
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#define _elf_set_element(set, symbol) \
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static const void *__elf_set_##set##_element_##symbol##__ \
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__attribute__ ((unused, section (#set))) = &(symbol)
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#else
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#define _elf_set_element(set, symbol) \
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static const void *const __elf_set_##set##_element_##symbol##__ \
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__attribute__ ((unused, section (#set))) = &(symbol)
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#endif
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/* Define SET as a symbol set. This may be required (it is in a.out) to
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be able to use the set's contents. */
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#define symbol_set_define(set) symbol_set_declare(set)
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/* Declare SET for use in this module, if defined in another module. */
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#define symbol_set_declare(set) \
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extern void *const __start_##set __attribute__ ((__weak__)); \
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extern void *const __stop_##set __attribute__ ((__weak__)); \
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weak_extern (__start_##set) weak_extern (__stop_##set)
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/* Return a pointer (void *const *) to the first element of SET. */
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#define symbol_set_first_element(set) (&__start_##set)
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/* Return true iff PTR (a void *const *) has been incremented
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past the last element in SET. */
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#define symbol_set_end_p(set, ptr) ((ptr) >= &__stop_##set)
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#else /* Not ELF: a.out. */
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#define text_set_element(set, symbol) \
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asm(".stabs \"" __SYMBOL_PREFIX #set "\",23,0,0," __SYMBOL_PREFIX #symbol)
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#define data_set_element(set, symbol) \
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asm(".stabs \"" __SYMBOL_PREFIX #set "\",25,0,0," __SYMBOL_PREFIX #symbol)
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#define bss_set_element(set, symbol) ?error Must use initialized data.
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#define symbol_set_define(set) void *const (set)[1];
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#define symbol_set_declare(set) extern void *const (set)[1];
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#define symbol_set_first_element(set) &(set)[1]
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#define symbol_set_end_p(set, ptr) (*(ptr) == 0)
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#endif /* ELF. */
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#endif /* Have GNU ld. */
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#endif /* libc-symbols.h */
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