math: x86 floor traps when FE_INEXACT is enabled (BZ 31601)

The implementations of floor functions using x87 floating point (i386 and
86_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>

5 files changed, 50 insertions, 107 deletions

diff --git a/sysdeps/i386/fpu/s_floor.S b/sysdeps/i386/fpu/s_floor.S
deleted file mode 100644
index 7143fdc..0000000
--- a/sysdeps/i386/fpu/s_floor.S
+++ /dev/null
@@ -1,34 +0,0 @@
-/*
- * Public domain.
- */
-
-#include <machine/asm.h>
-#include <libm-alias-double.h>
-
-RCSID("$NetBSD: s_floor.S,v 1.4 1995/05/09 00:01:59 jtc Exp $")
-
-ENTRY(__floor)
-	fldl	4(%esp)
-	subl	$32,%esp
-	cfi_adjust_cfa_offset (32)
-
-	fnstenv	4(%esp)			/* store fpu environment */
-
-	/* We use here %edx although only the low 1 bits are defined.
-	   But none of the operations should care and they are faster
-	   than the 16 bit operations.  */
-	movl	$0x400,%edx		/* round towards -oo */
-	orl	4(%esp),%edx
-	andl	$0xf7ff,%edx
-	movl	%edx,(%esp)
-	fldcw	(%esp)			/* load modified control word */
-
-	frndint				/* round */
-
-	fldenv	4(%esp)			/* restore original environment */
-
-	addl	$32,%esp
-	cfi_adjust_cfa_offset (-32)
-	ret
-END (__floor)
-libm_alias_double (__floor, floor)
diff --git a/sysdeps/i386/fpu/s_floor.c b/sysdeps/i386/fpu/s_floor.c
new file mode 100644
index 0000000..cc50e33
--- /dev/null
+++ b/sysdeps/i386/fpu/s_floor.c
@@ -0,0 +1,25 @@
+/* Return smallest integral value not less than argument.  i386 version.
+   Copyright (C) 2024 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <libm-alias-double.h>
+
+#define FUNC       __floor
+#define TYPE       double
+#define FE_OPTION  FE_DOWNWARD
+#include "s_nearestint_387_template.c"
+libm_alias_double (__floor, floor)
diff --git a/sysdeps/i386/fpu/s_floorf.S b/sysdeps/i386/fpu/s_floorf.S
deleted file mode 100644
index 8fad9c0..0000000
--- a/sysdeps/i386/fpu/s_floorf.S
+++ /dev/null
@@ -1,34 +0,0 @@
-/*
- * Public domain.
- */
-
-#include <machine/asm.h>
-#include <libm-alias-float.h>
-
-RCSID("$NetBSD: s_floorf.S,v 1.3 1995/05/09 00:04:32 jtc Exp $")
-
-ENTRY(__floorf)
-	flds	4(%esp)
-	subl	$32,%esp
-	cfi_adjust_cfa_offset (32)
-
-	fnstenv	4(%esp)			/* store fpu environment */
-
-	/* We use here %edx although only the low 1 bits are defined.
-	   But none of the operations should care and they are faster
-	   than the 16 bit operations.  */
-	movl	$0x400,%edx		/* round towards -oo */
-	orl	4(%esp),%edx
-	andl	$0xf7ff,%edx
-	movl	%edx,(%esp)
-	fldcw	(%esp)			/* load modified control word */
-
-	frndint				/* round */
-
-	fldenv	4(%esp)			/* restore original environment */
-
-	addl	$32,%esp
-	cfi_adjust_cfa_offset (-32)
-	ret
-END (__floorf)
-libm_alias_float (__floor, floor)
diff --git a/sysdeps/i386/fpu/s_floorf.c b/sysdeps/i386/fpu/s_floorf.c
new file mode 100644
index 0000000..fa9454e
--- /dev/null
+++ b/sysdeps/i386/fpu/s_floorf.c
@@ -0,0 +1,25 @@
+/* Largest integral value not greater than argument  i386 version.
+   Copyright (C) 2024 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <libm-alias-float.h>
+
+#define FUNC       __floorf
+#define TYPE       float
+#define FE_OPTION  FE_DOWNWARD
+#include "s_nearestint_387_template.c"
+libm_alias_float (__floor, floor)
diff --git a/sysdeps/i386/fpu/s_floorl.S b/sysdeps/i386/fpu/s_floorl.S
deleted file mode 100644
index 3ec28b4..0000000
--- a/sysdeps/i386/fpu/s_floorl.S
+++ /dev/null
@@ -1,39 +0,0 @@
-/*
- * Public domain.
- */
-
-#include <libm-alias-ldouble.h>
-#include <machine/asm.h>
-
-RCSID("$NetBSD: $")
-
-ENTRY(__floorl)
-	fldt	4(%esp)
-	subl	$32,%esp
-	cfi_adjust_cfa_offset (32)
-
-	fnstenv	4(%esp)			/* store fpu environment */
-
-	/* We use here %edx although only the low 1 bits are defined.
-	   But none of the operations should care and they are faster
-	   than the 16 bit operations.  */
-	movl	$0x400,%edx		/* round towards -oo */
-	orl	4(%esp),%edx
-	andl	$0xf7ff,%edx
-	movl	%edx,(%esp)
-	fldcw	(%esp)			/* load modified control word */
-
-	frndint				/* round */
-
-	/* Preserve "invalid" exceptions from sNaN input.  */
-	fnstsw
-	andl	$0x1, %eax
-	orl	%eax, 8(%esp)
-
-	fldenv	4(%esp)			/* restore original environment */
-
-	addl	$32,%esp
-	cfi_adjust_cfa_offset (-32)
-	ret
-END (__floorl)
-libm_alias_ldouble (__floor, floor)