Add libm_alias_finite for _finite symbols

This patch adds a new macro, libm_alias_finite, to define all _finite
symbol.  It sets all _finite symbol as compat symbol based on its first
version (obtained from the definition at built generated first-versions.h).

The <fn>f128_finite symbols were introduced in GLIBC 2.26 and so need
special treatment in code that is shared between long double and float128.
It is done by adding a list, similar to internal symbol redifinition,
on sysdeps/ieee754/float128/float128_private.h.

Alpha also needs some tricky changes to ensure we still emit 2 compat
symbols for sqrt(f).

Passes buildmanyglibc.

Co-authored-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>

1 files changed, 39 insertions, 0 deletions

diff --git a/sysdeps/ieee754/libm-alias-finite.h b/sysdeps/ieee754/libm-alias-finite.h
new file mode 100644
index 0000000000..95b8c04073
--- /dev/null
+++ b/sysdeps/ieee754/libm-alias-finite.h
@@ -0,0 +1,39 @@
+/* Finite math compatibility macros.
+   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
+   <http://www.gnu.org/licenses/>.  */
+
+#ifndef _LIBM_ALIAS_FINITE_H
+#define _LIBM_ALIAS_FINITE_H
+
+#include <first-versions.h>
+#include <shlib-compat.h>
+
+/* The -ffinite-math symbols were added on GLIBC 2.15 and moved to compat
+   symbol so newer architectures do not require to support it.  */
+#if SHLIB_COMPAT (libm, GLIBC_2_15, GLIBC_2_31)
+# define libm_alias_finite(from, to)				\
+  libm_alias_finite1(from, to)
+# define libm_alias_finite1(from, to)				\
+compat_symbol (libm,						\
+	       from,						\
+	       to ## _finite, 					\
+	       FIRST_VERSION_libm_ ## to ## _finite);
+#else
+# define libm_alias_finite(from, to)
+#endif
+
+#endif