btrfs-progs/config/ax_gcc_builtin.m4

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# ===========================================================================
# https://www.gnu.org/software/autoconf-archive/ax_gcc_builtin.html
# ===========================================================================
#
# SYNOPSIS
#
# AX_GCC_BUILTIN(BUILTIN)
#
# DESCRIPTION
#
# This macro checks if the compiler supports one of GCC's built-in
# functions; many other compilers also provide those same built-ins.
#
# The BUILTIN parameter is the name of the built-in function.
#
# If BUILTIN is supported define HAVE_<BUILTIN>. Keep in mind that since
# builtins usually start with two underscores they will be copied over
# into the HAVE_<BUILTIN> definition (e.g. HAVE___BUILTIN_EXPECT for
# __builtin_expect()).
#
# The macro caches its result in the ax_cv_have_<BUILTIN> variable (e.g.
# ax_cv_have___builtin_expect).
#
# The macro currently supports the following built-in functions:
#
# __builtin_assume_aligned
# __builtin_bswap16
# __builtin_bswap32
# __builtin_bswap64
# __builtin_choose_expr
# __builtin___clear_cache
# __builtin_clrsb
# __builtin_clrsbl
# __builtin_clrsbll
# __builtin_clz
# __builtin_clzl
# __builtin_clzll
# __builtin_complex
# __builtin_constant_p
# __builtin_cpu_init
# __builtin_cpu_is
# __builtin_cpu_supports
# __builtin_ctz
# __builtin_ctzl
# __builtin_ctzll
# __builtin_expect
# __builtin_ffs
# __builtin_ffsl
# __builtin_ffsll
# __builtin_fpclassify
# __builtin_huge_val
# __builtin_huge_valf
# __builtin_huge_vall
# __builtin_inf
# __builtin_infd128
# __builtin_infd32
# __builtin_infd64
# __builtin_inff
# __builtin_infl
# __builtin_isinf_sign
# __builtin_nan
# __builtin_nand128
# __builtin_nand32
# __builtin_nand64
# __builtin_nanf
# __builtin_nanl
# __builtin_nans
# __builtin_nansf
# __builtin_nansl
# __builtin_object_size
# __builtin_parity
# __builtin_parityl
# __builtin_parityll
# __builtin_popcount
# __builtin_popcountl
# __builtin_popcountll
# __builtin_powi
# __builtin_powif
# __builtin_powil
# __builtin_prefetch
# __builtin_trap
# __builtin_types_compatible_p
# __builtin_unreachable
#
# New:
# __builtin_add_overflow
# __builtin_sub_overflow
# __builtin_mul_overflow
#
# Unsupported built-ins will be tested with an empty parameter set and the
# result of the check might be wrong or meaningless so use with care.
#
# LICENSE
#
# Copyright (c) 2013 Gabriele Svelto <gabriele.svelto@gmail.com>
#
# Copying and distribution of this file, with or without modification, are
# permitted in any medium without royalty provided the copyright notice
# and this notice are preserved. This file is offered as-is, without any
# warranty.
#serial 7
AC_DEFUN([AX_GCC_BUILTIN], [
AS_VAR_PUSHDEF([ac_var], [ax_cv_have_$1])
AC_CACHE_CHECK([for $1], [ac_var], [
AC_LINK_IFELSE([AC_LANG_PROGRAM([], [
m4_case([$1],
[__builtin_assume_aligned], [$1("", 0)],
[__builtin_bswap16], [$1(0)],
[__builtin_bswap32], [$1(0)],
[__builtin_bswap64], [$1(0)],
[__builtin_choose_expr], [$1(0, 0, 0)],
[__builtin___clear_cache], [$1("", "")],
[__builtin_clrsb], [$1(0)],
[__builtin_clrsbl], [$1(0)],
[__builtin_clrsbll], [$1(0)],
[__builtin_clz], [$1(0)],
[__builtin_clzl], [$1(0)],
[__builtin_clzll], [$1(0)],
[__builtin_complex], [$1(0.0, 0.0)],
[__builtin_constant_p], [$1(0)],
[__builtin_cpu_init], [$1()],
[__builtin_cpu_is], [$1("intel")],
[__builtin_cpu_supports], [$1("sse")],
[__builtin_cpu_supports__pclmul], [__builtin_cpu_supports("pclmul")],
[__builtin_ctz], [$1(0)],
[__builtin_ctzl], [$1(0)],
[__builtin_ctzll], [$1(0)],
[__builtin_expect], [$1(0, 0)],
[__builtin_ffs], [$1(0)],
[__builtin_ffsl], [$1(0)],
[__builtin_ffsll], [$1(0)],
[__builtin_fpclassify], [$1(0, 1, 2, 3, 4, 0.0)],
[__builtin_huge_val], [$1()],
[__builtin_huge_valf], [$1()],
[__builtin_huge_vall], [$1()],
[__builtin_inf], [$1()],
[__builtin_infd128], [$1()],
[__builtin_infd32], [$1()],
[__builtin_infd64], [$1()],
[__builtin_inff], [$1()],
[__builtin_infl], [$1()],
[__builtin_isinf_sign], [$1(0.0)],
[__builtin_nan], [$1("")],
[__builtin_nand128], [$1("")],
[__builtin_nand32], [$1("")],
[__builtin_nand64], [$1("")],
[__builtin_nanf], [$1("")],
[__builtin_nanl], [$1("")],
[__builtin_nans], [$1("")],
[__builtin_nansf], [$1("")],
[__builtin_nansl], [$1("")],
[__builtin_object_size], [$1("", 0)],
[__builtin_parity], [$1(0)],
[__builtin_parityl], [$1(0)],
[__builtin_parityll], [$1(0)],
[__builtin_popcount], [$1(0)],
[__builtin_popcountl], [$1(0)],
[__builtin_popcountll], [$1(0)],
[__builtin_powi], [$1(0, 0)],
[__builtin_powif], [$1(0, 0)],
[__builtin_powil], [$1(0, 0)],
[__builtin_prefetch], [$1("")],
[__builtin_trap], [$1()],
[__builtin_types_compatible_p], [$1(int, int)],
[__builtin_unreachable], [$1()],
[__builtin_add_overflow], [$1(0, 1, (int *)0)],
[__builtin_sub_overflow], [$1(0, 1, (int *)0)],
[__builtin_mul_overflow], [$1(0, 1, (int *)0)],
[m4_warn([syntax], [Unsupported built-in $1, the test may fail])
$1()]
)
])],
[AS_VAR_SET([ac_var], [yes])],
[AS_VAR_SET([ac_var], [no])])
])
AS_IF([test yes = AS_VAR_GET([ac_var])],
[AC_DEFINE_UNQUOTED(AS_TR_CPP(HAVE_$1), 1,
[Define to 1 if the system has the `$1' built-in function])], [])
AS_VAR_POPDEF([ac_var])
])