AArch64: Add support for roundeven[f]

Add inline assembler for the roundeven functions.
Passes GLIBC regression.  Note GCC does not inline the builtin (PR100966),
so this cannot be used for now.

(cherry picked from commit 6a86bc099219a656be479d5f31ff90ec7860b112)

2 files changed, 57 insertions, 0 deletions

diff --git a/sysdeps/aarch64/fpu/s_roundeven.c b/sysdeps/aarch64/fpu/s_roundeven.c
new file mode 100644
index 0000000000..d74b40daf5
--- /dev/null
+++ b/sysdeps/aarch64/fpu/s_roundeven.c
@@ -0,0 +1,29 @@
+/* Copyright (C) 2021 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/>.  */
+
+#include <math.h>
+#include <libm-alias-double.h>
+
+double
+__roundeven (double x)
+{
+  asm volatile ("frintn \t%d0, %d1" : "=w" (x) : "w" (x));
+  return x;
+}
+hidden_def (__roundeven)
+libm_alias_double (__roundeven, roundeven)
diff --git a/sysdeps/aarch64/fpu/s_roundevenf.c b/sysdeps/aarch64/fpu/s_roundevenf.c
new file mode 100644
index 0000000000..dfc492c2f8
--- /dev/null
+++ b/sysdeps/aarch64/fpu/s_roundevenf.c
@@ -0,0 +1,28 @@
+/* Copyright (C) 2021 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/>.  */
+
+#include <math.h>
+#include <libm-alias-float.h>
+
+float
+__roundevenf (float x)
+{
+  asm volatile ("frintn \t%s0, %s1" : "=w" (x) : "w" (x));
+  return x;
+}
+libm_alias_float (__roundeven, roundeven)