Merge commit 'a39d4083cab589d7cd6a13e8a4b8db8875261d75'

[gnulib.git] / m4 / modff.m4

diff --git a/m4/modff.m4 b/m4/modff.m4
index faf58e3..3e78138 100644 (file)
--- a/m4/modff.m4
+++ b/m4/modff.m4
@@ -1,21 +1,93 @@
-# modff.m4 serial 2
-dnl Copyright (C) 2011 Free Software Foundation, Inc.
+# modff.m4 serial 5
+dnl Copyright (C) 2011-2014 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_MODFF],
 [
+  m4_divert_text([DEFAULTS], [gl_modff_required=plain])
   AC_REQUIRE([gl_MATH_H_DEFAULTS])
   AC_REQUIRE([gl_FUNC_MODF])
 
+  dnl Persuade glibc <math.h> to declare modff().
+  AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
+
   dnl Test whether modff() exists. We cannot assume that modff(), if it
   dnl exists, is defined in the same library as modf(). This is not the case
   dnl on FreeBSD, NetBSD, OpenBSD.
   gl_MATHFUNC([modff], [float], [(float, float *)])
-  if test $gl_cv_func_modff_no_libm = no \
-     && test $gl_cv_func_modff_in_libm = no; then
+  if test $gl_cv_func_modff_no_libm = yes \
+     || test $gl_cv_func_modff_in_libm = yes; then
+    :
+    m4_ifdef([gl_FUNC_MODFF_IEEE], [
+      if test $gl_modff_required = ieee && test $REPLACE_MODFF = 0; then
+        AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+        AC_CACHE_CHECK([whether modff works according to ISO C 99 with IEC 60559],
+          [gl_cv_func_modff_ieee],
+          [
+            save_LIBS="$LIBS"
+            LIBS="$LIBS $MODFF_LIBM"
+            AC_RUN_IFELSE(
+              [AC_LANG_SOURCE([[
+#ifndef __NO_MATH_INLINES
+# define __NO_MATH_INLINES 1 /* for glibc */
+#endif
+#include <math.h>
+]gl_FLOAT_MINUS_ZERO_CODE[
+]gl_FLOAT_SIGNBIT_CODE[
+/* Compare two numbers with ==.
+   This is a separate function because IRIX 6.5 "cc -O" miscompiles an
+   'x == x' test.  */
+static int
+numeric_equal (float x, float y)
+{
+  return x == y;
+}
+static float dummy (float x, float *iptr) { return 0; }
+float zero;
+float minus_one = - 1.0f;
+int main (int argc, char *argv[])
+{
+  float (*my_modff) (float, float *) = argc ? modff : dummy;
+  int result = 0;
+  float i;
+  float f;
+  /* Test modff(NaN,...).
+     This test fails on NetBSD 5.1, OpenBSD 4.9, Solaris 9, Cygwin.  */
+  f = my_modff (zero / zero, &i);
+  if (numeric_equal (f, f))
+    result |= 1;
+  /* Test modff(-Inf,...).
+     This test fails on IRIX 6.5, OSF/1 5.1, mingw.  */
+  f = my_modff (minus_one / zero, &i);
+  if (!(f == 0.0f) || (signbitf (minus_zerof) && !signbitf (f)))
+    result |= 2;
+  return result;
+}
+              ]])],
+              [gl_cv_func_modff_ieee=yes],
+              [gl_cv_func_modff_ieee=no],
+              [case "$host_os" in
+                         # Guess yes on glibc systems.
+                 *-gnu*) gl_cv_func_modff_ieee="guessing yes" ;;
+                         # If we don't know, assume the worst.
+                 *)      gl_cv_func_modff_ieee="guessing no" ;;
+               esac
+              ])
+            LIBS="$save_LIBS"
+          ])
+        case "$gl_cv_func_modff_ieee" in
+          *yes) ;;
+          *) REPLACE_MODFF=1 ;;
+        esac
+      fi
+    ])
+  else
     HAVE_MODFF=0
+  fi
+  if test $HAVE_MODFF = 0 || test $REPLACE_MODFF = 1; then
+    dnl Find libraries needed to link lib/modff.c.
     MODFF_LIBM="$MODF_LIBM"
   fi
   AC_SUBST([MODFF_LIBM])