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>
This commit is contained in:
Adhemerval Zanella 2024-04-03 16:39:17 -03:00
parent 87cb1dfcd6
commit 637bfc392f
10 changed files with 181 additions and 141 deletions

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@ -498,6 +498,7 @@ tests = \
bug-nextafter \ bug-nextafter \
bug-nexttoward \ bug-nexttoward \
bug-tgmath1 \ bug-tgmath1 \
test-ceil-except-2 \
test-femode \ test-femode \
test-femode-traps \ test-femode-traps \
test-fenv basic-test \ test-fenv basic-test \
@ -989,6 +990,8 @@ CFLAGS-test-fe-snans-always-signal.c += $(config-cflags-signaling-nans)
CFLAGS-test-nan-const.c += -fno-builtin CFLAGS-test-nan-const.c += -fno-builtin
CFLAGS-test-ceil-except-2.c += -fno-builtin
include ../Rules include ../Rules
gen-all-calls = $(gen-libm-calls) $(gen-calls) gen-all-calls = $(gen-libm-calls) $(gen-calls)

67
math/test-ceil-except-2.c Normal file
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@ -0,0 +1,67 @@
/* Test ceil functions do not disable exception traps.
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 <fenv.h>
#include <math.h>
#include <stdio.h>
#ifndef FE_INEXACT
# define FE_INEXACT 0
#endif
#define TEST_FUNC(NAME, FLOAT, SUFFIX) \
static int \
NAME (void) \
{ \
int result = 0; \
volatile FLOAT a, b __attribute__ ((unused)); \
a = 1.5; \
/* ceil must work when traps on "inexact" are enabled. */ \
b = ceil ## SUFFIX (a); \
/* And it must have left those traps enabled. */ \
if (fegetexcept () == FE_INEXACT) \
puts ("PASS: " #FLOAT); \
else \
{ \
puts ("FAIL: " #FLOAT); \
result = 1; \
} \
return result; \
}
TEST_FUNC (float_test, float, f)
TEST_FUNC (double_test, double, )
TEST_FUNC (ldouble_test, long double, l)
static int
do_test (void)
{
if (feenableexcept (FE_INEXACT) == -1)
{
puts ("enabling FE_INEXACT traps failed, cannot test");
return 77;
}
int result = float_test ();
feenableexcept (FE_INEXACT);
result |= double_test ();
feenableexcept (FE_INEXACT);
result |= ldouble_test ();
return result;
}
#include <support/test-driver.c>

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@ -1,34 +0,0 @@
/*
* Public domain.
*/
#include <machine/asm.h>
#include <libm-alias-double.h>
RCSID("$NetBSD: s_ceil.S,v 1.4 1995/05/08 23:52:13 jtc Exp $")
ENTRY(__ceil)
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 $0x0800,%edx /* round towards +oo */
orl 4(%esp),%edx
andl $0xfbff,%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 (__ceil)
libm_alias_double (__ceil, ceil)

25
sysdeps/i386/fpu/s_ceil.c Normal file
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@ -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 __ceil
#define TYPE double
#define FE_OPTION FE_UPWARD
#include "s_nearestint_387_template.c"
libm_alias_double (__ceil, ceil)

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@ -1,34 +0,0 @@
/*
* Public domain.
*/
#include <machine/asm.h>
#include <libm-alias-float.h>
RCSID("$NetBSD: s_ceilf.S,v 1.3 1995/05/08 23:52:44 jtc Exp $")
ENTRY(__ceilf)
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 $0x0800,%edx /* round towards +oo */
orl 4(%esp),%edx
andl $0xfbff,%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 (__ceilf)
libm_alias_float (__ceil, ceil)

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@ -0,0 +1,25 @@
/* Return largest 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-float.h>
#define FUNC __ceilf
#define TYPE float
#define FE_OPTION FE_UPWARD
#include "s_nearestint_387_template.c"
libm_alias_float (__ceil, ceil)

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@ -1,39 +0,0 @@
/*
* Public domain.
*/
#include <libm-alias-ldouble.h>
#include <machine/asm.h>
RCSID("$NetBSD: $")
ENTRY(__ceill)
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 $0x0800,%edx /* round towards +oo */
orl 4(%esp),%edx
andl $0xfbff,%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 (__ceill)
libm_alias_ldouble (__ceil, ceil)

25
sysdeps/x86/fpu/s_ceill.c Normal file
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@ -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)

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@ -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;
}

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@ -1,34 +0,0 @@
/*
* Public domain.
*/
#include <libm-alias-ldouble.h>
#include <machine/asm.h>
ENTRY(__ceill)
fldt 8(%rsp)
fnstenv -28(%rsp) /* 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 $0x0800,%edx /* round towards +oo */
orl -28(%rsp),%edx
andl $0xfbff,%edx
movl %edx,-32(%rsp)
fldcw -32(%rsp) /* load modified control word */
frndint /* round */
/* Preserve "invalid" exceptions from sNaN input. */
fnstsw
andl $0x1, %eax
orl %eax, -24(%rsp)
fldenv -28(%rsp) /* restore original environment */
ret
END (__ceill)
libm_alias_ldouble (__ceil, ceil)