gcc/config/linux.h

/* Definitions for systems using the Linux kernel, with or without
   MMU, using ELF at the compiler level but possibly FLT for final
   linked executables and shared libraries in some no-MMU cases, and
   possibly with a choice of libc implementations.
   Copyright (C) 1995-2013 Free Software Foundation, Inc.
   Contributed by Eric Youngdale.
   Modified for stabs-in-ELF by H.J. Lu (hjl@lucon.org).

This file is part of GCC.

GCC 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 3, or (at your option)
any later version.

GCC 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.

Under Section 7 of GPL version 3, you are granted additional
permissions described in the GCC Runtime Library Exception, version
3.1, as published by the Free Software Foundation.

You should have received a copy of the GNU General Public License and
a copy of the GCC Runtime Library Exception along with this program;
see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
<http://www.gnu.org/licenses/>.  */

/* C libraries supported on Linux.  */
#ifdef SINGLE_LIBC
#define OPTION_GLIBC  (DEFAULT_LIBC == LIBC_GLIBC)
#define OPTION_UCLIBC (DEFAULT_LIBC == LIBC_UCLIBC)
#define OPTION_BIONIC (DEFAULT_LIBC == LIBC_BIONIC)
#else
#define OPTION_GLIBC  (linux_libc == LIBC_GLIBC)
#define OPTION_UCLIBC (linux_libc == LIBC_UCLIBC)
#define OPTION_BIONIC (linux_libc == LIBC_BIONIC)
#endif

#define GNU_USER_TARGET_OS_CPP_BUILTINS()			\
    do {							\
	if (OPTION_GLIBC)					\
	  builtin_define ("__gnu_linux__");			\
	builtin_define_std ("linux");				\
	builtin_define_std ("unix");				\
	builtin_assert ("system=linux");			\
	builtin_assert ("system=unix");				\
	builtin_assert ("system=posix");			\
    } while (0)

/* Determine which dynamic linker to use depending on whether GLIBC or
   uClibc or Bionic is the default C library and whether
   -muclibc or -mglibc or -mbionic has been passed to change the default.  */

#define CHOOSE_DYNAMIC_LINKER1(LIBC1, LIBC2, LIBC3, LD1, LD2, LD3)	\
  "%{" LIBC2 ":" LD2 ";:%{" LIBC3 ":" LD3 ";:" LD1 "}}"

#if DEFAULT_LIBC == LIBC_GLIBC
#define CHOOSE_DYNAMIC_LINKER(G, U, B) \
  CHOOSE_DYNAMIC_LINKER1 ("mglibc", "muclibc", "mbionic", G, U, B)
#elif DEFAULT_LIBC == LIBC_UCLIBC
#define CHOOSE_DYNAMIC_LINKER(G, U, B) \
  CHOOSE_DYNAMIC_LINKER1 ("muclibc", "mglibc", "mbionic", U, G, B)
#elif DEFAULT_LIBC == LIBC_BIONIC
#define CHOOSE_DYNAMIC_LINKER(G, U, B) \
  CHOOSE_DYNAMIC_LINKER1 ("mbionic", "mglibc", "muclibc", B, G, U)
#else
#error "Unsupported DEFAULT_LIBC"
#endif /* DEFAULT_LIBC */

/* For most targets the following definitions suffice;
   GLIBC_DYNAMIC_LINKER must be defined for each target using them, or
   GLIBC_DYNAMIC_LINKER32 and GLIBC_DYNAMIC_LINKER64 for targets
   supporting both 32-bit and 64-bit compilation.  */
#define UCLIBC_DYNAMIC_LINKER "/lib/ld-uClibc.so.0"
#define UCLIBC_DYNAMIC_LINKER32 "/lib/ld-uClibc.so.0"
#define UCLIBC_DYNAMIC_LINKER64 "/lib/ld64-uClibc.so.0"
#define UCLIBC_DYNAMIC_LINKERX32 "/lib/ldx32-uClibc.so.0"
#define BIONIC_DYNAMIC_LINKER "/system/bin/linker"
#define BIONIC_DYNAMIC_LINKER32 "/system/bin/linker"
#define BIONIC_DYNAMIC_LINKER64 "/system/bin/linker64"
#define BIONIC_DYNAMIC_LINKERX32 "/system/bin/linkerx32"

#define GNU_USER_DYNAMIC_LINKER						\
  CHOOSE_DYNAMIC_LINKER (GLIBC_DYNAMIC_LINKER, UCLIBC_DYNAMIC_LINKER,	\
			 BIONIC_DYNAMIC_LINKER)
#define GNU_USER_DYNAMIC_LINKER32					\
  CHOOSE_DYNAMIC_LINKER (GLIBC_DYNAMIC_LINKER32, UCLIBC_DYNAMIC_LINKER32, \
			 BIONIC_DYNAMIC_LINKER32)
#define GNU_USER_DYNAMIC_LINKER64					\
  CHOOSE_DYNAMIC_LINKER (GLIBC_DYNAMIC_LINKER64, UCLIBC_DYNAMIC_LINKER64, \
			 BIONIC_DYNAMIC_LINKER64)
#define GNU_USER_DYNAMIC_LINKERX32					\
  CHOOSE_DYNAMIC_LINKER (GLIBC_DYNAMIC_LINKERX32, UCLIBC_DYNAMIC_LINKERX32, \
			 BIONIC_DYNAMIC_LINKERX32)

/* Determine whether the entire c99 runtime
   is present in the runtime library.  */
#undef TARGET_C99_FUNCTIONS
#define TARGET_C99_FUNCTIONS (OPTION_GLIBC)

/* Whether we have sincos that follows the GNU extension.  */
#undef TARGET_HAS_SINCOS
#define TARGET_HAS_SINCOS (OPTION_GLIBC || OPTION_BIONIC)

/* Whether we have Bionic libc runtime */
#undef TARGET_HAS_BIONIC
#define TARGET_HAS_BIONIC (OPTION_BIONIC)