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glibc/config.h.in
Stefan Liebler 022dfdce00 Add configure check to test if gcc supports attribute ifunc. 
This patch adds a configure check to test if gcc supports attribute ifunc.
The support can either be enabled in <gcc-src>/gcc/config.gcc for one
architecture in general by setting default_gnu_indirect_function variable to yes
or by configuring gcc with --enable-gnu-indirect-function.

The next patch rewrites libc_ifunc macro to use gcc attribute ifunc instead
of inline assembly to generate the IFUNC symbols due to false debuginfo.

If gcc does not support attribute ifunc, the old approach for generating
ifunc'ed symbols is used. Then the debug-information is false. Thus it is
recommended to use a gcc with indirect function support (See notes in INSTALL).
After this patch-series these inline assemblies for ifunc-handling are not
scattered in multiple files but are used only indirect via ifunc-macros
and can simply removed in libc-symbols.h in future.

If glibc is configured with --enable-multi-arch and gcc does not support
attribute ifunc, a configure warning is dumped!

ChangeLog:

	* config.h.in (HAVE_GCC_IFUNC): New undef.
	* configure.ac: Add check if gcc supports attribute ifunc feature.
	* configure: Regenerated.
	* manual/install.texi: Add recommendation for gcc with
	indirect-function support.
	* INSTALL: Regenerated.
2016-10-07 10:02:59 +02:00

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#if !defined IS_IN_build && !defined __ASSEMBLER__ && !defined _ISOMAC \
&& !defined __OPTIMIZE__
# error "glibc cannot be compiled without optimization"
#endif
/* Another evil option when it comes to compiling the C library is
--ffast-math since it alters the ABI. */
#if defined __FAST_MATH__ && !defined TEST_FAST_MATH
# error "glibc must not be compiled with -ffast-math"
#endif
/* Define if building with SELinux support. Set by --with-selinux. */
#undef HAVE_SELINUX
/* Defined if building with SELinux support & audit libs are detected. */
#undef HAVE_LIBAUDIT
/* Defined if building with SELinux support & libcap libs are detected. */
#undef HAVE_LIBCAP
/* Define to the assembler line separator character for multiple
assembler instructions per line. Default is `;' */
#undef ASM_LINE_SEP
/* Define if __attribute__((section("foo"))) puts quotes around foo. */
#undef HAVE_SECTION_QUOTES
/* Define if the assembler supports the `.set' directive. */
#undef HAVE_ASM_SET_DIRECTIVE
/* On powerpc64, use overlapping .opd entries. */
#undef USE_PPC64_OVERLAPPING_OPD
/* Define if _Unwind_Find_FDE should be exported from glibc. */
#undef EXPORT_UNWIND_FIND_FDE
/* Define if static NSS modules are wanted. */
#undef DO_STATIC_NSS
/* Assume that the compiler supports __builtin_expect.
This macro is necessary for proper compilation of code
shared between GNU libc and GNU gettext projects. */
#define HAVE_BUILTIN_EXPECT 1
/* Define if the compiler supports __builtin_memset. */
#undef HAVE_BUILTIN_MEMSET
/* Define if compiler accepts -ftree-loop-distribute-patterns. */
#undef HAVE_CC_INHIBIT_LOOP_TO_LIBCALL
/* Define if the regparm attribute shall be used for local functions
(gcc on ix86 only). */
#undef USE_REGPARMS
/* Defined on SPARC if GCC emits GOTDATA relocations. */
#undef HAVE_GCC_GOTDATA
/* Define on SPARC if AS supports VIS3 instructions. */
#undef HAVE_AS_VIS3_SUPPORT
/* Define if the linker supports the -z combreloc option. */
#undef HAVE_Z_COMBRELOC
/* Define if _rtld_local structure should be forced into .sdata section. */
#undef HAVE_SDATA_SECTION
/* Define if compiler supports AVX512. */
#undef HAVE_AVX512_SUPPORT
/* Define if assembler supports AVX512DQ. */
#undef HAVE_AVX512DQ_ASM_SUPPORT
/* Define if assembler supports z196 zarch instructions as default on S390. */
#undef HAVE_S390_MIN_Z196_ZARCH_ASM_SUPPORT
/* Define if assembler supports vector instructions on S390. */
#undef HAVE_S390_VX_ASM_SUPPORT
/* Define if gcc supports vector registers as clobbers in inline assembly
on S390. */
#undef HAVE_S390_VX_GCC_SUPPORT
/* Define if assembler supports Intel MPX. */
#undef HAVE_MPX_SUPPORT
/* Define if the compiler\'s exception support is based on libunwind. */
#undef HAVE_CC_WITH_LIBUNWIND
/* Define if the access to static and hidden variables is position independent
and does not need relocations. */
#undef PI_STATIC_AND_HIDDEN
/* Define this to disable the 'hidden_proto' et al macros in
include/libc-symbols.h that avoid PLT slots in the shared objects. */
#undef NO_HIDDEN
/* Define this to disable lazy relocations in DSOs. */
#undef BIND_NOW
/* AArch64 big endian ABI */
#undef HAVE_AARCH64_BE
/* Defined to some form of __attribute__ ((...)) if the compiler supports
a different, more efficient calling convention. */
#if defined USE_REGPARMS && !defined PROF
# define internal_function __attribute__ ((regparm (3), stdcall))
#endif
/* Linux specific: minimum supported kernel version. */
#undef __LINUX_KERNEL_VERSION
/* Override abi-tags ABI version if necessary. */
#undef __ABI_TAG_VERSION
/* bash 2.0 introduced the _XXX_GNU_nonoption_argv_flags_ variable to help
getopt determine whether a parameter is a flag or not. This features
was disabled later since it caused trouble. We are by default therefore
disabling the support as well. */
#undef USE_NONOPTION_FLAGS
/* Mach/Hurd specific: define if mig supports the `retcode' keyword. */
#undef HAVE_MIG_RETCODE
/* Mach specific: define if the `host_page_size' RPC is available. */
#undef HAVE_HOST_PAGE_SIZE
/* Mach/i386 specific: define if the `i386_io_perm_*' RPCs are available. */
#undef HAVE_I386_IO_PERM_MODIFY
/* Mach/i386 specific: define if the `i386_set_gdt' RPC is available. */
#undef HAVE_I386_SET_GDT
/* Defined of libidn is available. */
#undef HAVE_LIBIDN
/* Define if inlined system calls are available. */
#undef HAVE_INLINED_SYSCALLS
/* Define if your compiler defaults to -msecure-plt mode on ppc. */
#undef HAVE_PPC_SECURE_PLT
/* Define if __stack_chk_guard canary should be randomized at program startup. */
#undef ENABLE_STACKGUARD_RANDOMIZE
/* Define if lock elision should be enabled by default. */
#undef ENABLE_LOCK_ELISION
/* Package description. */
#undef PKGVERSION
/* Bug reporting address. */
#undef REPORT_BUGS_TO
/* Define if multi-arch DSOs should be generated. */
#undef USE_MULTIARCH
/* Define if `.ctors' and `.dtors' sections shouldn't be used. */
#undef NO_CTORS_DTORS_SECTIONS
/* Define if obsolete RPC code should be made available for user-level code
to link against. */
#undef LINK_OBSOLETE_RPC
/* Define if Systemtap <sys/sdt.h> probes should be defined. */
#undef USE_STAP_PROBE
/* Define if library functions should try to contact the nscd daemon. */
#undef USE_NSCD
/* Define if the dynamic linker should consult an ld.so.cache file. */
#undef USE_LDCONFIG
/* Define to 1 if STT_GNU_IFUNC support actually works. */
#define HAVE_IFUNC 0
/* Define if gcc supports attribute ifunc. */
#undef HAVE_GCC_IFUNC
/* Define if the linker defines __ehdr_start. */
#undef HAVE_EHDR_START
/*
*/
#ifndef _LIBC
/* These symbols might be defined by some sysdeps configures.
They are used only in miscellaneous generator programs, not
in compiling libc itself. */
/* sysdeps/generic/configure.ac */
#undef HAVE_PSIGNAL
/* sysdeps/unix/configure.ac */
#undef HAVE_STRERROR
/* sysdeps/unix/common/configure.ac */
#undef HAVE_SYS_SIGLIST
#undef HAVE__SYS_SIGLIST
#undef HAVE__CTYPE_
#undef HAVE___CTYPE_
#undef HAVE___CTYPE
#undef HAVE__CTYPE__
#undef HAVE__CTYPE
#undef HAVE__LOCP
#endif
/*
*/
#ifdef _LIBC
/* The zic and zdump programs need these definitions. */
#define HAVE_STRERROR 1
/* The locale code needs these definitions. */
#define HAVE_REGEX 1
/* The ARM hard-float ABI is being used. */
#undef HAVE_ARM_PCS_VFP
/* The ARM movw/movt instructions using PC-relative relocs work right. */
#define ARM_PCREL_MOVW_OK 0
/* The pt_chown binary is being built and used by grantpt. */
#define HAVE_PT_CHOWN 0
/* Define if the compiler supports __builtin_trap without
any external dependencies such as making a function call. */
#define HAVE_BUILTIN_TRAP 0
/* ports/sysdeps/mips/configure.in */
/* Define if using the IEEE 754-2008 NaN encoding on the MIPS target. */
#undef HAVE_MIPS_NAN2008
/* The PowerPC64 ELFv2 ABI is being used. */
#undef HAVE_ELFV2_ABI
/* PowerPC32 uses fcfid for integer to floating point conversions. */
#define HAVE_PPC_FCFID 0
/* PowerPC32 uses fctidz for floating point to long long conversions. */
#define HAVE_PPC_FCTIDZ 0
#endif
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