X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;f=m4%2Fhypotl.m4;h=0f21dd2f0b9bfb293c364920d496d736f2962440;hb=a02ba4bf889fee4622db87f185c3d0af84d74ae7;hp=57b472f8ef00b929baf68873c097ab640a4b1f83;hpb=58d8afd0545d6321272bb7fb243db3295c5fdeec;p=gnulib.git

diff --git a/m4/hypotl.m4 b/m4/hypotl.m4
index 57b472f8e..0f21dd2f0 100644
--- a/m4/hypotl.m4
+++ b/m4/hypotl.m4
@@ -1,4 +1,4 @@
-# hypotl.m4 serial 1
+# hypotl.m4 serial 5
 dnl Copyright (C) 2012 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -6,9 +6,13 @@ dnl with or without modifications, as long as this notice is preserved.
 
 AC_DEFUN([gl_FUNC_HYPOTL],
 [
+  m4_divert_text([DEFAULTS], [gl_hypotl_required=plain])
   AC_REQUIRE([gl_MATH_H_DEFAULTS])
   AC_REQUIRE([gl_FUNC_HYPOT])
 
+  dnl Persuade glibc <math.h> to declare hypotl().
+  AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
+
   dnl Test whether hypotl() exists. Assume that hypotl(), if it exists, is
   dnl defined in the same library as hypot().
   save_LIBS="$LIBS"
@@ -17,8 +21,74 @@ AC_DEFUN([gl_FUNC_HYPOTL],
   LIBS="$save_LIBS"
   if test $ac_cv_func_hypotl = yes; then
     HYPOTL_LIBM="$HYPOT_LIBM"
+
+    save_LIBS="$LIBS"
+    LIBS="$LIBS $HYPOTL_LIBM"
+    gl_FUNC_HYPOTL_WORKS
+    LIBS="$save_LIBS"
+    case "$gl_cv_func_hypotl_works" in
+      *yes) ;;
+      *) REPLACE_HYPOTL=1 ;;
+    esac
+
+    m4_ifdef([gl_FUNC_HYPOTL_IEEE], [
+      if test $gl_hypotl_required = ieee && test $REPLACE_HYPOTL = 0; then
+        AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+        AC_CACHE_CHECK([whether hypotl works according to ISO C 99 with IEC 60559],
+          [gl_cv_func_hypotl_ieee],
+          [
+            save_LIBS="$LIBS"
+            LIBS="$LIBS $HYPOTL_LIBM"
+            AC_RUN_IFELSE(
+              [AC_LANG_SOURCE([[
+#ifndef __NO_MATH_INLINES
+# define __NO_MATH_INLINES 1 /* for glibc */
+#endif
+#include <math.h>
+/* Compare two numbers with ==.
+   This is a separate function because IRIX 6.5 "cc -O" miscompiles an
+   'x == x' test.  */
+static int
+numeric_equal (long double x, long double y)
+{
+  return x == y;
+}
+static long double dummy (long double x, long double y) { return 0; }
+long double zero;
+long double one = 1.0L;
+int main (int argc, char *argv[])
+{
+  long double (*my_hypotl) (long double, long double) = argc ? hypotl : dummy;
+  long double f;
+  /* Test hypotl(NaN,Infinity).
+     This test fails on OSF/1 5.1 and native Windows.  */
+  f = my_hypotl (zero / zero, one / zero);
+  if (!numeric_equal (f, f))
+    return 1;
+  return 0;
+}
+              ]])],
+              [gl_cv_func_hypotl_ieee=yes],
+              [gl_cv_func_hypotl_ieee=no],
+              [case "$host_os" in
+                         # Guess yes on glibc systems.
+                 *-gnu*) gl_cv_func_hypotl_ieee="guessing yes" ;;
+                         # If we don't know, assume the worst.
+                 *)      gl_cv_func_hypotl_ieee="guessing no" ;;
+               esac
+              ])
+            LIBS="$save_LIBS"
+          ])
+        case "$gl_cv_func_hypotl_ieee" in
+          *yes) ;;
+          *) REPLACE_HYPOTL=1 ;;
+        esac
+      fi
+    ])
   else
     HAVE_HYPOTL=0
+  fi
+  if test $HAVE_HYPOTL = 0 || test $REPLACE_HYPOTL = 1; then
     dnl Find libraries needed to link lib/hypotl.c.
     if test $HAVE_SAME_LONG_DOUBLE_AS_DOUBLE = 1; then
       HYPOTL_LIBM="$HYPOT_LIBM"
@@ -52,3 +122,55 @@ AC_DEFUN([gl_FUNC_HYPOTL],
   fi
   AC_SUBST([HYPOTL_LIBM])
 ])
+
+dnl Test whether hypotl() works.
+dnl On OpenBSD 5.1/SPARC,
+dnl hypotl (2.5541394760659556563446062497337725156L, 7.7893454113437840832487794525518765265L)
+dnl has rounding errors that eat up the last 8 to 9 decimal digits.
+AC_DEFUN([gl_FUNC_HYPOTL_WORKS],
+[
+  AC_REQUIRE([AC_PROG_CC])
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+  AC_CACHE_CHECK([whether hypotl works], [gl_cv_func_hypotl_works],
+    [
+      AC_RUN_IFELSE(
+        [AC_LANG_SOURCE([[
+#include <float.h>
+#include <math.h>
+static long double
+my_ldexpl (long double x, int d)
+{
+  for (; d > 0; d--)
+    x *= 2.0L;
+  for (; d < 0; d++)
+    x *= 0.5L;
+  return x;
+}
+volatile long double x;
+volatile long double y;
+volatile long double z;
+int main ()
+{
+  long double err;
+
+  x = 2.5541394760659556563446062497337725156L;
+  y = 7.7893454113437840832487794525518765265L;
+  z = hypotl (x, y);
+  err = z * z - (x * x + y * y);
+  err = my_ldexpl (err, LDBL_MANT_DIG);
+  if (err < 0)
+    err = - err;
+  if (err > 1000.0L)
+    return 1;
+  return 0;
+}
+]])],
+        [gl_cv_func_hypotl_works=yes],
+        [gl_cv_func_hypotl_works=no],
+        [case "$host_os" in
+           openbsd*) gl_cv_func_hypotl_works="guessing no";;
+           *)        gl_cv_func_hypotl_works="guessing yes";;
+         esac
+        ])
+    ])
+])