ldbl-128ibm: make ieee754.h work with IEEE 128 long double

Instead of attempting something more creative, just copy
the small struct from ldbl-128 and enable it when IEEE
long double is present, and update the ibm long double
variant if supported.

Likewise, provide a shadow copy of math_ldbl.h to prevent
the ibm128 specific long double header from poisoning
unrelated files due to it's usage in math_private.h.

Reviewed-by: Tulio Magno Quites Machado Filho <tuliom@linux.ibm.com>

1 files changed, 30 insertions, 0 deletions

diff --git a/sysdeps/ieee754/ldbl-128ibm-compat/math_ldbl.h b/sysdeps/ieee754/ldbl-128ibm-compat/math_ldbl.h
new file mode 100644
index 0000000000..352617e178
--- /dev/null
+++ b/sysdeps/ieee754/ldbl-128ibm-compat/math_ldbl.h
@@ -0,0 +1,30 @@
+/* Manipulation of the bit representation of 'long double' quantities.
+   Copyright (C) 2020 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   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
+   <https://www.gnu.org/licenses/>.  */
+
+#ifndef _MATH_LDBL_H_IBM128_COMPAT
+#define _MATH_LDBL_H_IBM128_COMPAT 1
+
+#include <bits/floatn.h>
+
+/* Trampoline in the ldbl-128ibm headers if building against the
+   old abi.  Otherwise, we have nothing to add. */
+#if __LONG_DOUBLE_USES_FLOAT128 == 0
+#include_next <math_ldbl.h>
+#endif
+
+#endif /* _MATH_LDBL_H_IBM128_COMPAT */