From: "H.J. Lu" <hjl.tools@gmail.com>
To: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Cc: libc-alpha@sourceware.org, Joseph Myers <josmyers@redhat.com>
Subject: Re: [PATCH 1/3] math: math: x86 ceill traps when FE_INEXACT is enabled (BZ 31600)
Date: Wed, 3 Apr 2024 13:03:09 -0700 [thread overview]
Message-ID: <CAMe9rOpwafZWn+X8QoZ_4X_XuHVpZrwf7J0Ci=diALm43B1bDg@mail.gmail.com> (raw)
In-Reply-To: <20240403193919.1533786-2-adhemerval.zanella@linaro.org>
On Wed, Apr 3, 2024 at 12:39 PM Adhemerval Zanella
<adhemerval.zanella@linaro.org> wrote:
>
> 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.
> ---
> math/Makefile | 3 +
> math/test-ceil-except-2.c | 67 +++++++++++++++++++++
> sysdeps/i386/fpu/s_ceil.S | 34 -----------
> sysdeps/i386/fpu/s_ceil.c | 25 ++++++++
> sysdeps/i386/fpu/s_ceilf.S | 34 -----------
> sysdeps/i386/fpu/s_ceilf.c | 25 ++++++++
> sysdeps/i386/fpu/s_ceill.S | 39 ------------
> sysdeps/x86/fpu/s_ceill.c | 25 ++++++++
> sysdeps/x86/fpu/s_nearestint_387_template.c | 36 +++++++++++
> sysdeps/x86_64/fpu/s_ceill.S | 34 -----------
> 10 files changed, 181 insertions(+), 141 deletions(-)
> create mode 100644 math/test-ceil-except-2.c
> delete mode 100644 sysdeps/i386/fpu/s_ceil.S
> create mode 100644 sysdeps/i386/fpu/s_ceil.c
> delete mode 100644 sysdeps/i386/fpu/s_ceilf.S
> create mode 100644 sysdeps/i386/fpu/s_ceilf.c
> delete mode 100644 sysdeps/i386/fpu/s_ceill.S
> create mode 100644 sysdeps/x86/fpu/s_ceill.c
> create mode 100644 sysdeps/x86/fpu/s_nearestint_387_template.c
> delete mode 100644 sysdeps/x86_64/fpu/s_ceill.S
>
> diff --git a/math/Makefile b/math/Makefile
> index 121a709121..d2a740eebe 100644
> --- a/math/Makefile
> +++ b/math/Makefile
> @@ -498,6 +498,7 @@ tests = \
> bug-nextafter \
> bug-nexttoward \
> bug-tgmath1 \
> + test-ceil-except-2 \
> test-femode \
> test-femode-traps \
> 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-ceil-except-2.c += -fno-builtin
> +
> include ../Rules
>
> gen-all-calls = $(gen-libm-calls) $(gen-calls)
> diff --git a/math/test-ceil-except-2.c b/math/test-ceil-except-2.c
> new file mode 100644
> index 0000000000..394a272d89
> --- /dev/null
> +++ b/math/test-ceil-except-2.c
> @@ -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>
> diff --git a/sysdeps/i386/fpu/s_ceil.S b/sysdeps/i386/fpu/s_ceil.S
> deleted file mode 100644
> index 99984f9b8d..0000000000
> --- a/sysdeps/i386/fpu/s_ceil.S
> +++ /dev/null
> @@ -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 $32,%esp
> - cfi_adjust_cfa_offset (-32)
> - ret
> -END (__ceil)
> -libm_alias_double (__ceil, ceil)
> diff --git a/sysdeps/i386/fpu/s_ceil.c b/sysdeps/i386/fpu/s_ceil.c
> new file mode 100644
> index 0000000000..349135c5d3
> --- /dev/null
> +++ b/sysdeps/i386/fpu/s_ceil.c
> @@ -0,0 +1,25 @@
> +/* Return smallest integral value not less than argument. i386 version.
> + Copyright (C) 2024 Free Software Foundation, Inc.
> + This file is part of the GNU C Library.
> +
> + The GNU C Library is free software; you can redistribute it and/or
> + modify it under the terms of the GNU Lesser General Public
> + License as published by the Free Software Foundation; either
> + version 2.1 of the License, or (at your option) any later version.
> +
> + The GNU C Library is distributed in the hope that it will be useful,
> + but WITHOUT ANY WARRANTY; without even the implied warranty of
> + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> + Lesser General Public License for more details.
> +
> + You should have received a copy of the GNU Lesser General Public
> + License along with the GNU C Library; if not, see
> + <https://www.gnu.org/licenses/>. */
> +
> +#include <libm-alias-double.h>
> +
> +#define FUNC __ceil
> +#define TYPE double
> +#define FE_OPTION FE_UPWARD
> +#include "s_nearestint_387_template.c"
> +libm_alias_double (__ceil, ceil)
> diff --git a/sysdeps/i386/fpu/s_ceilf.S b/sysdeps/i386/fpu/s_ceilf.S
> deleted file mode 100644
> index 03e8e22609..0000000000
> --- a/sysdeps/i386/fpu/s_ceilf.S
> +++ /dev/null
> @@ -1,34 +0,0 @@
> -/*
> - * Public domain.
> - */
> -
> -#include <machine/asm.h>
> -#include <libm-alias-float.h>
> -
> -RCSID("$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 $32,%esp
> - cfi_adjust_cfa_offset (-32)
> - ret
> -END (__ceilf)
> -libm_alias_float (__ceil, ceil)
> diff --git a/sysdeps/i386/fpu/s_ceilf.c b/sysdeps/i386/fpu/s_ceilf.c
> new file mode 100644
> index 0000000000..e73a20fd71
> --- /dev/null
> +++ b/sysdeps/i386/fpu/s_ceilf.c
> @@ -0,0 +1,25 @@
> +/* Return largest integral value not less than argument. i386 version.
> + Copyright (C) 2024 Free Software Foundation, Inc.
> + This file is part of the GNU C Library.
> +
> + The GNU C Library is free software; you can redistribute it and/or
> + modify it under the terms of the GNU Lesser General Public
> + License as published by the Free Software Foundation; either
> + version 2.1 of the License, or (at your option) any later version.
> +
> + The GNU C Library is distributed in the hope that it will be useful,
> + but WITHOUT ANY WARRANTY; without even the implied warranty of
> + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> + Lesser General Public License for more details.
> +
> + You should have received a copy of the GNU Lesser General Public
> + License along with the GNU C Library; if not, see
> + <https://www.gnu.org/licenses/>. */
> +
> +#include <libm-alias-float.h>
> +
> +#define FUNC __ceilf
> +#define TYPE float
> +#define FE_OPTION FE_UPWARD
> +#include "s_nearestint_387_template.c"
> +libm_alias_float (__ceil, ceil)
> diff --git a/sysdeps/i386/fpu/s_ceill.S b/sysdeps/i386/fpu/s_ceill.S
> deleted file mode 100644
> index a551fce7f9..0000000000
> --- a/sysdeps/i386/fpu/s_ceill.S
> +++ /dev/null
> @@ -1,39 +0,0 @@
> -/*
> - * Public domain.
> - */
> -
> -#include <libm-alias-ldouble.h>
> -#include <machine/asm.h>
> -
> -RCSID("$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)
> 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;
> +}
> diff --git a/sysdeps/x86_64/fpu/s_ceill.S b/sysdeps/x86_64/fpu/s_ceill.S
> deleted file mode 100644
> index 16dbecd56d..0000000000
> --- a/sysdeps/x86_64/fpu/s_ceill.S
> +++ /dev/null
> @@ -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)
> --
> 2.34.1
>
LGTM.
Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
Thanks.
--
H.J.
next prev parent reply other threads:[~2024-04-03 20:04 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-03 19:39 [PATCH 0/3] Improve x86 rounding implementation when FE_INEXACT trap is enabled Adhemerval Zanella
2024-04-03 19:39 ` [PATCH 1/3] math: math: x86 ceill traps when FE_INEXACT is enabled (BZ 31600) Adhemerval Zanella
2024-04-03 20:03 ` H.J. Lu [this message]
2024-04-03 19:39 ` [PATCH 2/3] math: math: x86 floor traps when FE_INEXACT is enabled (BZ 31601) Adhemerval Zanella
2024-04-03 20:03 ` H.J. Lu
2024-04-03 19:39 ` [PATCH 3/3] math: math: x86 trunc traps when FE_INEXACT is enabled (BZ 31603) Adhemerval Zanella
2024-04-03 20:04 ` H.J. Lu
2024-04-04 5:27 ` Paul Zimmermann
2024-04-04 11:52 ` Adhemerval Zanella Netto
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