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-rw-r--r--m4/log2l.m4109
1 files changed, 90 insertions, 19 deletions
diff --git a/m4/log2l.m4 b/m4/log2l.m4
index 47765434fe..31d5432664 100644
--- a/m4/log2l.m4
+++ b/m4/log2l.m4
@@ -1,5 +1,5 @@
-# log2l.m4 serial 2
-dnl Copyright (C) 2010-2021 Free Software Foundation, Inc.
+# log2l.m4 serial 8
+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.
@@ -15,10 +15,10 @@ AC_DEFUN([gl_FUNC_LOG2L],
dnl Test whether log2l() exists. Assume that log2l(), if it exists, is
dnl defined in the same library as log2().
- save_LIBS="$LIBS"
+ saved_LIBS="$LIBS"
LIBS="$LIBS $LOG2_LIBM"
- AC_CHECK_FUNCS([log2l])
- LIBS="$save_LIBS"
+ gl_CHECK_FUNCS_ANDROID([log2l], [[#include <math.h>]])
+ LIBS="$saved_LIBS"
if test $ac_cv_func_log2l = yes; then
LOG2L_LIBM="$LOG2_LIBM"
HAVE_LOG2L=1
@@ -26,10 +26,10 @@ AC_DEFUN([gl_FUNC_LOG2L],
dnl IRIX 6.5 has log2l() in libm but doesn't declare it in <math.h>.
AC_CHECK_DECL([log2l], , [HAVE_DECL_LOG2L=0], [[#include <math.h>]])
- save_LIBS="$LIBS"
+ saved_LIBS="$LIBS"
LIBS="$LIBS $LOG2L_LIBM"
gl_FUNC_LOG2L_WORKS
- LIBS="$save_LIBS"
+ LIBS="$saved_LIBS"
case "$gl_cv_func_log2l_works" in
*yes) ;;
*) REPLACE_LOG2L=1 ;;
@@ -37,6 +37,9 @@ AC_DEFUN([gl_FUNC_LOG2L],
else
HAVE_LOG2L=0
HAVE_DECL_LOG2L=0
+ case "$gl_cv_onwards_func_log2l" in
+ future*) REPLACE_LOG2L=1 ;;
+ esac
fi
if test $HAVE_LOG2L = 0 || test $REPLACE_LOG2L = 1; then
dnl Find libraries needed to link lib/log2l.c.
@@ -69,6 +72,7 @@ AC_DEFUN([gl_FUNC_LOG2L],
dnl Test whether log2l() works.
dnl On OSF/1 5.1, log2l(-0.0) is NaN.
+dnl On musl 1.2.2/{arm64,s390x}, the result is accurate to only 16 digits.
AC_DEFUN([gl_FUNC_LOG2L_WORKS],
[
AC_REQUIRE([AC_PROG_CC])
@@ -77,7 +81,40 @@ AC_DEFUN([gl_FUNC_LOG2L_WORKS],
[
AC_RUN_IFELSE(
[AC_LANG_SOURCE([[
+#ifndef __NO_MATH_INLINES
+# define __NO_MATH_INLINES 1 /* for glibc */
+#endif
+#include <float.h>
#include <math.h>
+/* Override the values of <float.h>, 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
#ifndef log2l /* for AIX */
extern
#ifdef __cplusplus
@@ -85,25 +122,59 @@ extern
#endif
long double log2l (long double);
#endif
-volatile long double x;
-volatile long double y;
-int main ()
+static long double dummy (long double x) { return 0; }
+volatile long double gx;
+volatile long double gy;
+int main (int argc, char *argv[])
{
+ long double (* volatile my_log2l) (long double) = argc ? log2l : dummy;
+ int result = 0;
/* This test fails on OSF/1 5.1. */
- x = -0.0L;
- y = log2l (x);
- if (!(y + y == y))
- return 1;
- return 0;
+ {
+ gx = -0.0L;
+ gy = my_log2l (gx);
+ if (!(gy + gy == gy))
+ result |= 1;
+ }
+ /* This test fails on musl 1.2.2/arm64, musl 1.2.2/s390x. */
+ {
+ 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 y = my_log2l (x);
+ long double z = my_log2l (1.0L / x);
+ long double err = (y + z) * TWO_LDBL_MANT_DIG;
+ if (!(err >= -10000.0L && err <= 10000.0L))
+ result |= 2;
+ }
+ /* This test fails on musl 1.2.2/arm64, musl 1.2.2/s390x. */
+ if (DBL_MAX_EXP < LDBL_MAX_EXP)
+ {
+ long double x = ldexpl (1.0L, DBL_MAX_EXP); /* finite! */
+ long double y = my_log2l (x);
+ if (y > 0 && y + y == y) /* infinite? */
+ result |= 4;
+ }
+ return result;
}
]])],
[gl_cv_func_log2l_works=yes],
[gl_cv_func_log2l_works=no],
[case "$host_os" in
- osf*) gl_cv_func_log2l_works="guessing no" ;;
- # Guess yes on native Windows.
- mingw*) gl_cv_func_log2l_works="guessing yes" ;;
- *) gl_cv_func_log2l_works="guessing yes" ;;
+ # Guess yes on glibc systems.
+ *-gnu* | gnu*) gl_cv_func_log2l_works="guessing yes" ;;
+ # Guess no on musl systems.
+ *-musl* | midipix*) gl_cv_func_log2l_works="guessing no" ;;
+ # Guess no on OSF/1.
+ osf*) gl_cv_func_log2l_works="guessing no" ;;
+ # Guess yes on native Windows.
+ mingw* | windows*) gl_cv_func_log2l_works="guessing yes" ;;
+ # If we don't know, obey --enable-cross-guesses.
+ *) gl_cv_func_log2l_works="$gl_cross_guess_normal" ;;
esac
])
])

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