1# ilogbl.m4 serial 5 2dnl Copyright (C) 2010-2021 Free Software Foundation, Inc. 3dnl This file is free software; the Free Software Foundation 4dnl gives unlimited permission to copy and/or distribute it, 5dnl with or without modifications, as long as this notice is preserved. 6 7AC_DEFUN([gl_FUNC_ILOGBL], 8[ 9 AC_REQUIRE([gl_MATH_H_DEFAULTS]) 10 AC_REQUIRE([gl_LONG_DOUBLE_VS_DOUBLE]) 11 AC_REQUIRE([gl_FUNC_ILOGB]) 12 13 dnl Persuade glibc <math.h> to declare ilogbl(). 14 AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS]) 15 16 dnl Test whether ilogbl() exists. Assume that ilogbl(), if it exists, is 17 dnl defined in the same library as ilogb(). 18 save_LIBS="$LIBS" 19 LIBS="$LIBS $ILOGB_LIBM" 20 AC_CACHE_CHECK([for ilogbl], 21 [gl_cv_func_ilogbl], 22 [ 23 AC_LINK_IFELSE( 24 [AC_LANG_PROGRAM( 25 [[#ifndef __NO_MATH_INLINES 26 # define __NO_MATH_INLINES 1 /* for glibc */ 27 #endif 28 #include <math.h> 29 int (*funcptr) (long double) = ilogbl; 30 long double x;]], 31 [[return (funcptr (x) % 2) == 0 32 || (ilogbl (x) % 2) == 0;]])], 33 [gl_cv_func_ilogbl=yes], 34 [gl_cv_func_ilogbl=no]) 35 ]) 36 LIBS="$save_LIBS" 37 if test $gl_cv_func_ilogbl = yes; then 38 ILOGBL_LIBM="$ILOGB_LIBM" 39 save_LIBS="$LIBS" 40 LIBS="$LIBS $ILOGBL_LIBM" 41 gl_FUNC_ILOGBL_WORKS 42 LIBS="$save_LIBS" 43 case "$gl_cv_func_ilogbl_works" in 44 *yes) ;; 45 *) REPLACE_ILOGBL=1 ;; 46 esac 47 else 48 HAVE_ILOGBL=0 49 fi 50 if test $HAVE_ILOGBL = 0 || test $REPLACE_ILOGBL = 1; then 51 dnl Find libraries needed to link lib/ilogbl.c. 52 if test $HAVE_SAME_LONG_DOUBLE_AS_DOUBLE = 1; then 53 ILOGBL_LIBM="$ILOGB_LIBM" 54 else 55 AC_REQUIRE([gl_FUNC_FREXPL]) 56 AC_REQUIRE([gl_FUNC_ISNANL]) 57 ILOGBL_LIBM= 58 dnl Append $FREXPL_LIBM to ILOGBL_LIBM, avoiding gratuitous duplicates. 59 case " $ILOGBL_LIBM " in 60 *" $FREXPL_LIBM "*) ;; 61 *) ILOGBL_LIBM="$ILOGBL_LIBM $FREXPL_LIBM" ;; 62 esac 63 dnl Append $ISNANL_LIBM to ILOGBL_LIBM, avoiding gratuitous duplicates. 64 case " $ILOGBL_LIBM " in 65 *" $ISNANL_LIBM "*) ;; 66 *) ILOGBL_LIBM="$ILOGBL_LIBM $ISNANL_LIBM" ;; 67 esac 68 fi 69 fi 70 AC_SUBST([ILOGBL_LIBM]) 71]) 72 73dnl Test whether ilogbl() works. 74dnl On Cygwin 2.9, ilogbl(0.0L) is wrong. 75dnl On AIX 7.1 in 64-bit mode, ilogbl(2^(LDBL_MIN_EXP-1)) is wrong. 76dnl On Haiku 2017, it returns i-2 instead of i-1 for values between 77dnl ca. 2^-16444 and ca. 2^-16382. 78AC_DEFUN([gl_FUNC_ILOGBL_WORKS], 79[ 80 AC_REQUIRE([AC_PROG_CC]) 81 AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles 82 AC_CACHE_CHECK([whether ilogbl works], [gl_cv_func_ilogbl_works], 83 [ 84 AC_RUN_IFELSE( 85 [AC_LANG_SOURCE([[ 86#include <float.h> 87#include <math.h> 88/* Override the values of <float.h>, like done in float.in.h. */ 89#if defined __i386__ && (defined __BEOS__ || defined __OpenBSD__) 90# undef LDBL_MIN_EXP 91# define LDBL_MIN_EXP (-16381) 92#endif 93#if defined __i386__ && (defined __FreeBSD__ || defined __DragonFly__) 94# undef LDBL_MIN_EXP 95# define LDBL_MIN_EXP (-16381) 96#endif 97#if (defined _ARCH_PPC || defined _POWER) && defined _AIX && (LDBL_MANT_DIG == 106) && defined __GNUC__ 98# undef LDBL_MIN_EXP 99# define LDBL_MIN_EXP DBL_MIN_EXP 100#endif 101#if defined __sgi && (LDBL_MANT_DIG >= 106) 102# if defined __GNUC__ 103# undef LDBL_MIN_EXP 104# define LDBL_MIN_EXP DBL_MIN_EXP 105# endif 106#endif 107volatile long double x; 108static int dummy (long double x) { return 0; } 109int main (int argc, char *argv[]) 110{ 111 int (* volatile my_ilogbl) (long double) = argc ? ilogbl : dummy; 112 int result = 0; 113 /* This test fails on Cygwin 2.9. */ 114 { 115 x = 0.0L; 116 if (my_ilogbl (x) != FP_ILOGB0) 117 result |= 1; 118 } 119 /* This test fails on AIX 7.1 in 64-bit mode. */ 120 { 121 int i; 122 x = 0.5L; 123 for (i = LDBL_MIN_EXP - 1; i < 0; i++) 124 x = x * 0.5L; 125 if (x > 0.0L && my_ilogbl (x) != LDBL_MIN_EXP - 2) 126 result |= 2; 127 } 128 /* This test fails on Haiku 2017. */ 129 { 130 int i; 131 for (i = 1, x = (long double)1.0; i >= LDBL_MIN_EXP-100 && x > (long double)0.0; i--, x *= (long double)0.5) 132 if (my_ilogbl (x) != i - 1) 133 { 134 result |= 4; 135 break; 136 } 137 } 138 return result; 139} 140]])], 141 [gl_cv_func_ilogbl_works=yes], 142 [gl_cv_func_ilogbl_works=no], 143 [case "$host_os" in 144 aix* | haiku*) 145 gl_cv_func_ilogbl_works="guessing no" ;; 146 # Guess yes on native Windows. 147 mingw*) gl_cv_func_ilogbl_works="guessing yes" ;; 148 *) gl_cv_func_ilogbl_works="guessing yes" ;; 149 esac 150 ]) 151 ]) 152]) 153