From: Noah Goldstein <goldstein.w.n@gmail.com>
To: "H.J. Lu" <hjl.tools@gmail.com>
Cc: Mayshao-oc <Mayshao-oc@zhaoxin.com>,
GNU C Library <libc-alpha@sourceware.org>,
"Carlos O'Donell" <carlos@systemhalted.org>
Subject: Re: [PATCH v1] x86: Remove generic strncat, strncpy, and stpncpy implementations
Date: Tue, 5 Jul 2022 19:05:42 -0700 [thread overview]
Message-ID: <CAFUsyfLDsgAHhxMtHtki+rVh9OyfQRB1uczgYFc8J0-SZftraA@mail.gmail.com> (raw)
In-Reply-To: <CAMe9rOo-SHN+QwQ6VptyeJZ+ik4M27Oxpe-O3Mw8GVL8TYC7LQ@mail.gmail.com>
On Tue, Jul 5, 2022 at 6:33 PM H.J. Lu <hjl.tools@gmail.com> wrote:
>
> On Tue, Jul 5, 2022 at 5:06 PM Noah Goldstein <goldstein.w.n@gmail.com> wrote:
> >
> > These functions all have optimized versions:
> > __strncat_sse2_unaligned, __strncpy_sse2_unaligned, and
> > stpncpy_sse2_unaligned which are faster than their respective generic
> > implementations. Since the sse2 versions can run on baseline x86_64,
>
> Is this true on all x86-64 processors?
That they are faster or that sse2 can run on baseline x86_64?
>
> > we should use these as the baseline implementation and can remove the
> > generic implementations.
> >
> > Geometric mean of N=20 runs of the entire benchmark suite on:
> > 11th Gen Intel(R) Core(TM) i7-1165G7 @ 2.80GHz (Tigerlake)
> >
> > __strncat_sse2_unaligned / __strncat_generic: .944
> > __strncpy_sse2_unaligned / __strncpy_generic: .726
> > __stpncpy_sse2_unaligned / __stpncpy_generic: .650
> >
> > Tested build with and without multiarch and full check with multiarch.
> > ---
> > sysdeps/x86_64/multiarch/Makefile | 3 --
> > sysdeps/x86_64/multiarch/ifunc-impl-list.c | 9 ++--
> > sysdeps/x86_64/multiarch/ifunc-strcpy.h | 8 +---
> > sysdeps/x86_64/multiarch/ifunc-strncpy.h | 48 ++++++++++++++++++++++
> > sysdeps/x86_64/multiarch/stpncpy-generic.c | 26 ------------
> > sysdeps/x86_64/multiarch/stpncpy.c | 3 +-
> > sysdeps/x86_64/multiarch/strncat-generic.c | 21 ----------
> > sysdeps/x86_64/multiarch/strncat.c | 3 +-
> > sysdeps/x86_64/multiarch/strncpy-generic.c | 24 -----------
> > sysdeps/x86_64/multiarch/strncpy.c | 3 +-
> > 10 files changed, 56 insertions(+), 92 deletions(-)
> > create mode 100644 sysdeps/x86_64/multiarch/ifunc-strncpy.h
> > delete mode 100644 sysdeps/x86_64/multiarch/stpncpy-generic.c
> > delete mode 100644 sysdeps/x86_64/multiarch/strncat-generic.c
> > delete mode 100644 sysdeps/x86_64/multiarch/strncpy-generic.c
> >
> > diff --git a/sysdeps/x86_64/multiarch/Makefile b/sysdeps/x86_64/multiarch/Makefile
> > index 18cea04423..04e238efa0 100644
> > --- a/sysdeps/x86_64/multiarch/Makefile
> > +++ b/sysdeps/x86_64/multiarch/Makefile
> > @@ -45,7 +45,6 @@ sysdep_routines += \
> > stpcpy-sse2-unaligned \
> > stpncpy-avx2 \
> > stpncpy-avx2-rtm \
> > - stpncpy-generic \
> > stpncpy-evex \
> > stpncpy-sse2-unaligned \
> > strcasecmp_l-avx2 \
> > @@ -92,7 +91,6 @@ sysdep_routines += \
> > strncase_l-sse4_2 \
> > strncat-avx2 \
> > strncat-avx2-rtm \
> > - strncat-generic \
> > strncat-evex \
> > strncat-sse2-unaligned \
> > strncmp-avx2 \
> > @@ -102,7 +100,6 @@ sysdep_routines += \
> > strncmp-sse4_2 \
> > strncpy-avx2 \
> > strncpy-avx2-rtm \
> > - strncpy-generic \
> > strncpy-evex \
> > strncpy-sse2-unaligned \
> > strnlen-avx2 \
> > diff --git a/sysdeps/x86_64/multiarch/ifunc-impl-list.c b/sysdeps/x86_64/multiarch/ifunc-impl-list.c
> > index adf7d4bafd..2c96cb62d2 100644
> > --- a/sysdeps/x86_64/multiarch/ifunc-impl-list.c
> > +++ b/sysdeps/x86_64/multiarch/ifunc-impl-list.c
> > @@ -403,8 +403,7 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
> > && CPU_FEATURE_USABLE (AVX512BW)),
> > __stpncpy_evex)
> > IFUNC_IMPL_ADD (array, i, stpncpy, 1,
> > - __stpncpy_sse2_unaligned)
> > - IFUNC_IMPL_ADD (array, i, stpncpy, 1, __stpncpy_generic))
> > + __stpncpy_sse2_unaligned))
> >
> > /* Support sysdeps/x86_64/multiarch/stpcpy.c. */
> > IFUNC_IMPL (i, name, stpcpy,
> > @@ -618,8 +617,7 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
> > && CPU_FEATURE_USABLE (AVX512BW)),
> > __strncat_evex)
> > IFUNC_IMPL_ADD (array, i, strncat, 1,
> > - __strncat_sse2_unaligned)
> > - IFUNC_IMPL_ADD (array, i, strncat, 1, __strncat_generic))
> > + __strncat_sse2_unaligned))
> >
> > /* Support sysdeps/x86_64/multiarch/strncpy.c. */
> > IFUNC_IMPL (i, name, strncpy,
> > @@ -634,8 +632,7 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
> > && CPU_FEATURE_USABLE (AVX512BW)),
> > __strncpy_evex)
> > IFUNC_IMPL_ADD (array, i, strncpy, 1,
> > - __strncpy_sse2_unaligned)
> > - IFUNC_IMPL_ADD (array, i, strncpy, 1, __strncpy_generic))
> > + __strncpy_sse2_unaligned))
> >
> > /* Support sysdeps/x86_64/multiarch/strpbrk.c. */
> > IFUNC_IMPL (i, name, strpbrk,
> > diff --git a/sysdeps/x86_64/multiarch/ifunc-strcpy.h b/sysdeps/x86_64/multiarch/ifunc-strcpy.h
> > index 80529458d1..a15afa44e9 100644
> > --- a/sysdeps/x86_64/multiarch/ifunc-strcpy.h
> > +++ b/sysdeps/x86_64/multiarch/ifunc-strcpy.h
> > @@ -20,11 +20,7 @@
> >
> > #include <init-arch.h>
> >
> > -#ifndef GENERIC
> > -# define GENERIC sse2
> > -#endif
> > -
> > -extern __typeof (REDIRECT_NAME) OPTIMIZE (GENERIC) attribute_hidden;
> > +extern __typeof (REDIRECT_NAME) OPTIMIZE (sse2) attribute_hidden;
> > extern __typeof (REDIRECT_NAME) OPTIMIZE (sse2_unaligned)
> > attribute_hidden;
> > extern __typeof (REDIRECT_NAME) OPTIMIZE (avx2) attribute_hidden;
> > @@ -53,5 +49,5 @@ IFUNC_SELECTOR (void)
> > if (CPU_FEATURES_ARCH_P (cpu_features, Fast_Unaligned_Load))
> > return OPTIMIZE (sse2_unaligned);
> >
> > - return OPTIMIZE (GENERIC);
> > + return OPTIMIZE (sse2);
> > }
> > diff --git a/sysdeps/x86_64/multiarch/ifunc-strncpy.h b/sysdeps/x86_64/multiarch/ifunc-strncpy.h
> > new file mode 100644
> > index 0000000000..323225af4d
> > --- /dev/null
> > +++ b/sysdeps/x86_64/multiarch/ifunc-strncpy.h
> > @@ -0,0 +1,48 @@
> > +/* Common definition for ifunc st{r|p}n{cpy|cat}
> > + All versions must be listed in ifunc-impl-list.c.
> > + Copyright (C) 2022 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 <init-arch.h>
> > +
> > +extern __typeof (REDIRECT_NAME) OPTIMIZE (sse2_unaligned)
> > + attribute_hidden;
> > +extern __typeof (REDIRECT_NAME) OPTIMIZE (avx2) attribute_hidden;
> > +extern __typeof (REDIRECT_NAME) OPTIMIZE (avx2_rtm) attribute_hidden;
> > +extern __typeof (REDIRECT_NAME) OPTIMIZE (evex) attribute_hidden;
> > +
> > +static inline void *
> > +IFUNC_SELECTOR (void)
> > +{
> > + const struct cpu_features* cpu_features = __get_cpu_features ();
> > +
> > + if (CPU_FEATURE_USABLE_P (cpu_features, AVX2)
> > + && CPU_FEATURES_ARCH_P (cpu_features, AVX_Fast_Unaligned_Load))
> > + {
> > + if (CPU_FEATURE_USABLE_P (cpu_features, AVX512VL)
> > + && CPU_FEATURE_USABLE_P (cpu_features, AVX512BW))
> > + return OPTIMIZE (evex);
> > +
> > + if (CPU_FEATURE_USABLE_P (cpu_features, RTM))
> > + return OPTIMIZE (avx2_rtm);
> > +
> > + if (!CPU_FEATURES_ARCH_P (cpu_features, Prefer_No_VZEROUPPER))
> > + return OPTIMIZE (avx2);
> > + }
> > +
> > + return OPTIMIZE (sse2_unaligned);
> > +}
> > diff --git a/sysdeps/x86_64/multiarch/stpncpy-generic.c b/sysdeps/x86_64/multiarch/stpncpy-generic.c
> > deleted file mode 100644
> > index 87826845b0..0000000000
> > --- a/sysdeps/x86_64/multiarch/stpncpy-generic.c
> > +++ /dev/null
> > @@ -1,26 +0,0 @@
> > -/* stpncpy.
> > - Copyright (C) 2022 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 STPNCPY __stpncpy_generic
> > -#undef weak_alias
> > -#define weak_alias(ignored1, ignored2)
> > -#undef libc_hidden_def
> > -#define libc_hidden_def(stpncpy)
> > -
> > -#include <string/stpncpy.c>
> > diff --git a/sysdeps/x86_64/multiarch/stpncpy.c b/sysdeps/x86_64/multiarch/stpncpy.c
> > index 879bc83f0b..a8d083ff0d 100644
> > --- a/sysdeps/x86_64/multiarch/stpncpy.c
> > +++ b/sysdeps/x86_64/multiarch/stpncpy.c
> > @@ -25,9 +25,8 @@
> > # undef stpncpy
> > # undef __stpncpy
> >
> > -# define GENERIC generic
> > # define SYMBOL_NAME stpncpy
> > -# include "ifunc-strcpy.h"
> > +# include "ifunc-strncpy.h"
> >
> > libc_ifunc_redirected (__redirect_stpncpy, __stpncpy, IFUNC_SELECTOR ());
> >
> > diff --git a/sysdeps/x86_64/multiarch/strncat-generic.c b/sysdeps/x86_64/multiarch/strncat-generic.c
> > deleted file mode 100644
> > index 0090669cd1..0000000000
> > --- a/sysdeps/x86_64/multiarch/strncat-generic.c
> > +++ /dev/null
> > @@ -1,21 +0,0 @@
> > -/* strncat.
> > - Copyright (C) 2022 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 STRNCAT __strncat_generic
> > -#include <string/strncat.c>
> > diff --git a/sysdeps/x86_64/multiarch/strncat.c b/sysdeps/x86_64/multiarch/strncat.c
> > index 50fba8a41f..a590c25d51 100644
> > --- a/sysdeps/x86_64/multiarch/strncat.c
> > +++ b/sysdeps/x86_64/multiarch/strncat.c
> > @@ -24,8 +24,7 @@
> > # undef strncat
> >
> > # define SYMBOL_NAME strncat
> > -# define GENERIC generic
> > -# include "ifunc-strcpy.h"
> > +# include "ifunc-strncpy.h"
> >
> > libc_ifunc_redirected (__redirect_strncat, strncat, IFUNC_SELECTOR ());
> > strong_alias (strncat, __strncat);
> > diff --git a/sysdeps/x86_64/multiarch/strncpy-generic.c b/sysdeps/x86_64/multiarch/strncpy-generic.c
> > deleted file mode 100644
> > index 9916153dd5..0000000000
> > --- a/sysdeps/x86_64/multiarch/strncpy-generic.c
> > +++ /dev/null
> > @@ -1,24 +0,0 @@
> > -/* strncpy.
> > - Copyright (C) 2022 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 STRNCPY __strncpy_generic
> > -#undef libc_hidden_builtin_def
> > -#define libc_hidden_builtin_def(strncpy)
> > -
> > -#include <string/strncpy.c>
> > diff --git a/sysdeps/x86_64/multiarch/strncpy.c b/sysdeps/x86_64/multiarch/strncpy.c
> > index 7fc7d72ec5..c83440f0e3 100644
> > --- a/sysdeps/x86_64/multiarch/strncpy.c
> > +++ b/sysdeps/x86_64/multiarch/strncpy.c
> > @@ -24,8 +24,7 @@
> > # undef strncpy
> >
> > # define SYMBOL_NAME strncpy
> > -# define GENERIC generic
> > -# include "ifunc-strcpy.h"
> > +# include "ifunc-strncpy.h"
> >
> > libc_ifunc_redirected (__redirect_strncpy, strncpy, IFUNC_SELECTOR ());
> >
> > --
> > 2.34.1
> >
>
>
> --
> H.J.
next prev parent reply other threads:[~2022-07-06 2:05 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-06 0:06 Noah Goldstein
2022-07-06 1:32 ` H.J. Lu
2022-07-06 2:05 ` Noah Goldstein [this message]
2022-07-06 2:14 ` Noah Goldstein
2022-07-06 2:47 ` Noah Goldstein
2022-07-06 7:42 ` Mayshao-oc
2022-07-06 18:49 ` Noah Goldstein
2022-07-07 2:57 ` Mayshao-oc
2022-07-07 3:11 ` Noah Goldstein
2022-07-12 18:43 ` Noah Goldstein
2022-07-06 18:08 ` H.J. Lu
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