Make common fdim implementation generic.

The only difference is the usage of math_narrow_eval when
building s_fdiml.c.  This should be harmless for long double,
but I did observe some code generation changes on m68k, but
lack the resources to test it.

Likewise, to more easily support overriding symbol generation,
the aliasing macros are always conditionally defined on their
absence to reduce boilerplate.

I also ran builds for i486, ppc64, sparcv9, aarch64,
s390x and observed no changes to s_fdim* objects.

1 files changed, 40 insertions, 0 deletions

diff --git a/math/s_fdim_template.c b/math/s_fdim_template.c
new file mode 100644
index 0000000000..d3e73790af
--- /dev/null
+++ b/math/s_fdim_template.c
@@ -0,0 +1,40 @@
+/* Return positive difference between arguments.
+   Copyright (C) 1997-2016 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <errno.h>
+#include <math.h>
+#include <math_private.h>
+
+FLOAT
+M_DECL_FUNC (__fdim) (FLOAT x, FLOAT y)
+{
+  if (islessequal (x, y))
+    return 0;
+
+  FLOAT r = math_narrow_eval (x - y);
+  if (isinf (r) && !isinf (x) && !isinf (y))
+    __set_errno (ERANGE);
+
+  return r;
+}
+declare_mgen_alias (__fdim, fdim);
+
+#if M_LIBM_NEED_COMPAT (fdim)
+declare_mgen_libm_compat (__fdim, fdim)
+#endif