X-Git-Url: https://erislabs.net/gitweb/?a=blobdiff_plain;f=m4%2Ffrexpf.m4;h=431fdd329cbfa3958bc1b0fe6a3052fc20076816;hb=da8054d48dc22e1c051db54049e005d51a006e69;hp=3aa648b69e71aa82d9268a22b922f7c87ee12fba;hpb=579cd92ebf7e6c45259e041957042a7d9cf3ac26;p=gnulib.git

diff --git a/m4/frexpf.m4 b/m4/frexpf.m4
index 3aa648b69..431fdd329 100644
--- a/m4/frexpf.m4
+++ b/m4/frexpf.m4
@@ -1,5 +1,5 @@
-# frexpf.m4 serial 2
-dnl Copyright (C) 2011 Free Software Foundation, Inc.
+# frexpf.m4 serial 5
+dnl Copyright (C) 2011-2013 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.
@@ -9,14 +9,88 @@ AC_DEFUN([gl_FUNC_FREXPF],
   AC_REQUIRE([gl_MATH_H_DEFAULTS])
   AC_REQUIRE([gl_FUNC_FREXP])
 
+  dnl Persuade glibc <math.h> to declare frexpf().
+  AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
+
   dnl Test whether frexpf() exists. We cannot assume that frexpf(), if it
   dnl exists, is defined in the same library as frexp(). This is not the case
   dnl on NetBSD, OpenBSD.
   gl_MATHFUNC([frexpf], [float], [(float, int *)])
-  if test $gl_cv_func_frexpf_no_libm = no \
-     && test $gl_cv_func_frexpf_in_libm = no; then
+  if test $gl_cv_func_frexpf_no_libm = yes \
+     || test $gl_cv_func_frexpf_in_libm = yes; then
+    save_LIBS="$LIBS"
+    LIBS="$LIBS $FREXPF_LIBM"
+    gl_FUNC_FREXPF_WORKS
+    LIBS="$save_LIBS"
+    case "$gl_cv_func_frexpf_works" in
+      *yes) ;;
+      *)    REPLACE_FREXPF=1 ;;
+    esac
+  else
     HAVE_FREXPF=0
+  fi
+  if test $HAVE_FREXPF = 0 || test $REPLACE_FREXPF = 1; then
     FREXPF_LIBM="$FREXP_LIBM"
   fi
   AC_SUBST([FREXPF_LIBM])
 ])
+
+dnl Test whether frexpf() works also on infinite numbers (this fails e.g. on
+dnl IRIX 6.5 and mingw) and on negative zero (this fails e.g. on mingw).
+AC_DEFUN([gl_FUNC_FREXPF_WORKS],
+[
+  AC_REQUIRE([AC_PROG_CC])
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+  AC_CACHE_CHECK([whether frexpf works], [gl_cv_func_frexpf_works],
+    [
+      AC_RUN_IFELSE(
+        [AC_LANG_SOURCE([[
+#include <float.h>
+#include <math.h>
+#include <string.h>
+/* HP cc on HP-UX 10.20 has a bug with the constant expression -0.0.
+   ICC 10.0 has a bug when optimizing the expression -zero.
+   The expression -FLT_MIN * FLT_MIN does not work when cross-compiling
+   to PowerPC on Mac OS X 10.5.  */
+#if defined __hpux || defined __sgi || defined __ICC
+static float
+compute_minus_zero (void)
+{
+  return -FLT_MIN * FLT_MIN;
+}
+# define minus_zero compute_minus_zero ()
+#else
+float minus_zero = -0.0f;
+#endif
+int main()
+{
+  int result = 0;
+  volatile float x;
+  float zero = 0.0f;
+  /* Test on infinite numbers.  */
+  x = 1.0f / zero;
+  {
+    int exp;
+    float y = frexpf (x, &exp);
+    if (y != x)
+      result |= 1;
+  }
+  /* Test on negative zero.  */
+  x = minus_zero;
+  {
+    int exp;
+    float y = frexpf (x, &exp);
+    if (memcmp (&y, &x, sizeof x))
+      result |= 2;
+  }
+  return result;
+}]])],
+        [gl_cv_func_frexpf_works=yes],
+        [gl_cv_func_frexpf_works=no],
+        [case "$host_os" in
+           irix* | mingw*) gl_cv_func_frexpf_works="guessing no";;
+           *)              gl_cv_func_frexpf_works="guessing yes";;
+         esac
+        ])
+    ])
+])