# expl.m4 serial 20 dnl Copyright (C) 2010-2024 Free Software Foundation, Inc. dnl This file is free software; the Free Software Foundation dnl gives unlimited permission to copy and/or distribute it, dnl with or without modifications, as long as this notice is preserved. AC_DEFUN([gl_FUNC_EXPL], [ AC_REQUIRE([gl_MATH_H_DEFAULTS]) AC_REQUIRE([gl_LONG_DOUBLE_VS_DOUBLE]) AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles dnl Persuade glibc to declare expl(). AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS]) EXPL_LIBM= AC_CACHE_CHECK([whether expl() can be used without linking with libm], [gl_cv_func_expl_no_libm], [ AC_LINK_IFELSE( [AC_LANG_PROGRAM( [[#ifndef __NO_MATH_INLINES # define __NO_MATH_INLINES 1 /* for glibc */ #endif #include long double (* volatile funcptr) (long double) = expl; long double x;]], [[return funcptr (x) > 1.5 || expl (x) > 1.5;]])], [gl_cv_func_expl_no_libm=yes], [gl_cv_func_expl_no_libm=no]) ]) if test $gl_cv_func_expl_no_libm = no; then AC_CACHE_CHECK([whether expl() can be used with libm], [gl_cv_func_expl_in_libm], [ save_LIBS="$LIBS" LIBS="$LIBS -lm" AC_LINK_IFELSE( [AC_LANG_PROGRAM( [[#ifndef __NO_MATH_INLINES # define __NO_MATH_INLINES 1 /* for glibc */ #endif #include long double (* volatile funcptr) (long double) = expl; long double x;]], [[return funcptr (x) > 1.5 || expl (x) > 1.5;]])], [gl_cv_func_expl_in_libm=yes], [gl_cv_func_expl_in_libm=no]) LIBS="$save_LIBS" ]) if test $gl_cv_func_expl_in_libm = yes; then EXPL_LIBM=-lm fi fi if test $gl_cv_func_expl_no_libm = yes \ || test $gl_cv_func_expl_in_libm = yes; then dnl Also check whether it's declared. dnl Mac OS X 10.3 has expl() in libc but doesn't declare it in . AC_CHECK_DECL([expl], , [HAVE_DECL_EXPL=0], [[#include ]]) if test $REPLACE_EXPL = 0; then AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles AC_CACHE_CHECK([whether expl works], [gl_cv_func_expl_works], [ save_LIBS="$LIBS" LIBS="$LIBS $EXPL_LIBM" AC_RUN_IFELSE( [AC_LANG_SOURCE([[ #ifndef __NO_MATH_INLINES # define __NO_MATH_INLINES 1 /* for glibc */ #endif #include #include /* Override the values of , like done in float.in.h. */ #if defined __i386__ && (defined __BEOS__ || defined __OpenBSD__) # undef LDBL_MANT_DIG # define LDBL_MANT_DIG 64 # undef LDBL_MIN_EXP # define LDBL_MIN_EXP (-16381) # undef LDBL_MAX_EXP # define LDBL_MAX_EXP 16384 #endif #if defined __i386__ && (defined __FreeBSD__ || defined __DragonFly__) # undef LDBL_MANT_DIG # define LDBL_MANT_DIG 64 # undef LDBL_MIN_EXP # define LDBL_MIN_EXP (-16381) # undef LDBL_MAX_EXP # define LDBL_MAX_EXP 16384 #endif #if (defined _ARCH_PPC || defined _POWER) && defined _AIX && (LDBL_MANT_DIG == 106) && defined __GNUC__ # undef LDBL_MIN_EXP # define LDBL_MIN_EXP DBL_MIN_EXP #endif #if defined __sgi && (LDBL_MANT_DIG >= 106) # undef LDBL_MANT_DIG # define LDBL_MANT_DIG 106 # if defined __GNUC__ # undef LDBL_MIN_EXP # define LDBL_MIN_EXP DBL_MIN_EXP # endif #endif #undef expl extern #ifdef __cplusplus "C" #endif long double expl (long double); static long double dummy (long double x) { return 0; } int main (int argc, char *argv[]) { long double (* volatile my_expl) (long double) = argc ? expl : dummy; int result = 0; /* On Haiku 2017 the system's native expl() is just a stub: it returns 0.0 and prints "__expl not implemented" for all arguments. */ { volatile long double x1 = -1.0; if (expl (x1) == 0.0) result |= 1; } /* On OpenBSD 5.4 the system's native expl() is buggy: it returns 'nan' for small values. */ { volatile long double x1 = -1.0; volatile long double x2 = -0.8; volatile long double x3 = -0.4; if (isnan (expl (x1)) || isnan (expl (x2)) || isnan (expl (x3))) result |= 2; } /* This test fails on musl 1.2.2/arm64, musl 1.2.2/s390x, NetBSD 9.0. */ { const long double TWO_LDBL_MANT_DIG = /* 2^LDBL_MANT_DIG */ (long double) (1U << ((LDBL_MANT_DIG - 1) / 5)) * (long double) (1U << ((LDBL_MANT_DIG - 1 + 1) / 5)) * (long double) (1U << ((LDBL_MANT_DIG - 1 + 2) / 5)) * (long double) (1U << ((LDBL_MANT_DIG - 1 + 3) / 5)) * (long double) (1U << ((LDBL_MANT_DIG - 1 + 4) / 5)); long double x = 11.358L; long double err = (my_expl (x) * my_expl (- x) - 1.0L) * TWO_LDBL_MANT_DIG; if (!(err >= -100.0L && err <= 100.0L)) result |= 4; } return result; } ]])], [gl_cv_func_expl_works=yes], [gl_cv_func_expl_works=no], [case "$host_os" in # Guess yes on glibc systems. *-gnu* | gnu*) gl_cv_func_expl_works="guessing yes" ;; # Guess no on musl systems. *-musl* | midipix*) gl_cv_func_expl_works="guessing no" ;; # Guess yes on native Windows. mingw* | windows*) gl_cv_func_expl_works="guessing yes" ;; # If we don't know, obey --enable-cross-guesses. *) gl_cv_func_expl_works="$gl_cross_guess_normal" ;; esac ]) LIBS="$save_LIBS" ]) case "$gl_cv_func_expl_works" in *yes) ;; *) REPLACE_EXPL=1 ;; esac fi else HAVE_DECL_EXPL=0 HAVE_EXPL=0 fi if test $HAVE_EXPL = 0 || test $REPLACE_EXPL = 1; then dnl Find libraries needed to link lib/expl.c. if test $HAVE_SAME_LONG_DOUBLE_AS_DOUBLE = 1; then AC_REQUIRE([gl_FUNC_EXP]) EXPL_LIBM="$EXP_LIBM" else AC_REQUIRE([gl_FUNC_ISNANL]) AC_REQUIRE([gl_FUNC_ROUNDL]) AC_REQUIRE([gl_FUNC_LDEXPL]) EXPL_LIBM= dnl Append $ISNANL_LIBM to EXPL_LIBM, avoiding gratuitous duplicates. case " $EXPL_LIBM " in *" $ISNANL_LIBM "*) ;; *) EXPL_LIBM="$EXPL_LIBM $ISNANL_LIBM" ;; esac dnl Append $ROUNDL_LIBM to EXPL_LIBM, avoiding gratuitous duplicates. case " $EXPL_LIBM " in *" $ROUNDL_LIBM "*) ;; *) EXPL_LIBM="$EXPL_LIBM $ROUNDL_LIBM" ;; esac dnl Append $LDEXPL_LIBM to EXPL_LIBM, avoiding gratuitous duplicates. case " $EXPL_LIBM " in *" $LDEXPL_LIBM "*) ;; *) EXPL_LIBM="$EXPL_LIBM $LDEXPL_LIBM" ;; esac fi fi AC_SUBST([EXPL_LIBM]) ])