math: x86 ceill traps when FE_INEXACT is enabled (BZ 31600)

The implementations of ceil functions using x87 floating point (i386 and
x86_64 long double only) traps when FE_INEXACT is enabled.  Although
this is a GNU extension outside the scope of the C standard, other
architectures that also support traps do not show this behavior.

The fix moves the implementation to a common one that holds any
exceptions with a 'fnclex' (libc_feholdexcept_setround_387).

Checked on x86_64-linux-gnu and i686-linux-gnu.
Reviewed-by: H.J. Lu <hjl.tools@gmail.com>

2 files changed, 61 insertions, 0 deletions

diff --git a/sysdeps/x86/fpu/s_ceill.c b/sysdeps/x86/fpu/s_ceill.c
new file mode 100644
index 0000000000..860dd2c960
--- /dev/null
+++ b/sysdeps/x86/fpu/s_ceill.c
@@ -0,0 +1,25 @@
+/* Return smallest integral value not less than argument.  x86 version.
+   Copyright (C) 2024 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 <libm-alias-ldouble.h>
+
+#define FUNC       __ceill
+#define TYPE       long double
+#define FE_OPTION  FE_UPWARD
+#include "s_nearestint_387_template.c"
+libm_alias_ldouble (__ceil, ceil)
diff --git a/sysdeps/x86/fpu/s_nearestint_387_template.c b/sysdeps/x86/fpu/s_nearestint_387_template.c
new file mode 100644
index 0000000000..95fca93f87
--- /dev/null
+++ b/sysdeps/x86/fpu/s_nearestint_387_template.c
@@ -0,0 +1,36 @@
+/* Nearest integet template for x86.
+   Copyright (C) 2024 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/>.  */
+
+#define NO_MATH_REDIRECT
+#include <math.h>
+#include <fenv_private.h>
+
+TYPE
+FUNC (TYPE x)
+{
+  fenv_t fenv;
+  TYPE r;
+
+  libc_feholdexcept_setround_387 (&fenv, FE_OPTION);
+  asm volatile ("frndint" : "=t" (r) : "0" (x));
+  /* Preserve "invalid" exceptions from sNaN input.  */
+  fenv.__status_word |= libc_fetestexcept_387 (FE_INVALID);
+  libc_fesetenv_387 (&fenv);
+
+  return r;
+}