From: Noah Goldstein <goldstein.w.n@gmail.com>
To: libc-alpha@sourceware.org
Subject: [PATCH v3 2/3] x86: Move and slightly improve memset_erms
Date: Wed, 29 Jun 2022 16:07:05 -0700 [thread overview]
Message-ID: <20220629230706.1264225-2-goldstein.w.n@gmail.com> (raw)
In-Reply-To: <20220629230706.1264225-1-goldstein.w.n@gmail.com>
Implementation wise:
1. Remove the VZEROUPPER as memset_{impl}_unaligned_erms does not
use the L(stosb) label that was previously defined.
2. Don't give the hotpath (fallthrough) to zero size.
Code positioning wise:
Move memset_{chk}_erms to its own file. Leaving it in between the
memset_{impl}_unaligned both adds unnecessary complexity to the
file and wastes space in a relatively hot cache section.
---
sysdeps/x86_64/multiarch/Makefile | 1 +
sysdeps/x86_64/multiarch/memset-erms.S | 44 +++++++++++++++++++
.../multiarch/memset-vec-unaligned-erms.S | 31 -------------
3 files changed, 45 insertions(+), 31 deletions(-)
create mode 100644 sysdeps/x86_64/multiarch/memset-erms.S
diff --git a/sysdeps/x86_64/multiarch/Makefile b/sysdeps/x86_64/multiarch/Makefile
index 62a4d96fb8..18cea04423 100644
--- a/sysdeps/x86_64/multiarch/Makefile
+++ b/sysdeps/x86_64/multiarch/Makefile
@@ -30,6 +30,7 @@ sysdep_routines += \
memset-avx2-unaligned-erms-rtm \
memset-avx512-no-vzeroupper \
memset-avx512-unaligned-erms \
+ memset-erms \
memset-evex-unaligned-erms \
memset-sse2-unaligned-erms \
rawmemchr-avx2 \
diff --git a/sysdeps/x86_64/multiarch/memset-erms.S b/sysdeps/x86_64/multiarch/memset-erms.S
new file mode 100644
index 0000000000..e83cccc731
--- /dev/null
+++ b/sysdeps/x86_64/multiarch/memset-erms.S
@@ -0,0 +1,44 @@
+/* memset implement with rep stosb
+ 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 <sysdep.h>
+
+#if defined USE_MULTIARCH && IS_IN (libc)
+ .text
+ENTRY (__memset_chk_erms)
+ cmp %RDX_LP, %RCX_LP
+ jb HIDDEN_JUMPTARGET (__chk_fail)
+END (__memset_chk_erms)
+
+/* Only used to measure performance of REP STOSB. */
+ENTRY (__memset_erms)
+ /* Skip zero length. */
+ test %RDX_LP, %RDX_LP
+ jz L(stosb_return_zero)
+ mov %RDX_LP, %RCX_LP
+ movzbl %sil, %eax
+ mov %RDI_LP, %RDX_LP
+ rep stosb
+ mov %RDX_LP, %RAX_LP
+ ret
+L(stosb_return_zero):
+ movq %rdi, %rax
+ ret
+END (__memset_erms)
+#endif
diff --git a/sysdeps/x86_64/multiarch/memset-vec-unaligned-erms.S b/sysdeps/x86_64/multiarch/memset-vec-unaligned-erms.S
index abc12d9cda..905d0fa464 100644
--- a/sysdeps/x86_64/multiarch/memset-vec-unaligned-erms.S
+++ b/sysdeps/x86_64/multiarch/memset-vec-unaligned-erms.S
@@ -156,37 +156,6 @@ L(entry_from_wmemset):
#if defined USE_MULTIARCH && IS_IN (libc)
END (MEMSET_SYMBOL (__memset, unaligned))
-# if VEC_SIZE == 16
-ENTRY (__memset_chk_erms)
- cmp %RDX_LP, %RCX_LP
- jb HIDDEN_JUMPTARGET (__chk_fail)
-END (__memset_chk_erms)
-
-/* Only used to measure performance of REP STOSB. */
-ENTRY (__memset_erms)
- /* Skip zero length. */
- test %RDX_LP, %RDX_LP
- jnz L(stosb)
- movq %rdi, %rax
- ret
-# else
-/* Provide a hidden symbol to debugger. */
- .hidden MEMSET_SYMBOL (__memset, erms)
-ENTRY (MEMSET_SYMBOL (__memset, erms))
-# endif
-L(stosb):
- mov %RDX_LP, %RCX_LP
- movzbl %sil, %eax
- mov %RDI_LP, %RDX_LP
- rep stosb
- mov %RDX_LP, %RAX_LP
- VZEROUPPER_RETURN
-# if VEC_SIZE == 16
-END (__memset_erms)
-# else
-END (MEMSET_SYMBOL (__memset, erms))
-# endif
-
# if defined SHARED && IS_IN (libc)
ENTRY_CHK (MEMSET_CHK_SYMBOL (__memset_chk, unaligned_erms))
cmp %RDX_LP, %RCX_LP
--
2.34.1
next prev parent reply other threads:[~2022-06-29 23:07 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-28 15:27 [PATCH v1 1/3] x86: Add definition for __wmemset_chk AVX2 RTM in ifunc impl list Noah Goldstein
2022-06-28 15:27 ` [PATCH v1 2/3] x86: Move and slightly improve memset_erms Noah Goldstein
2022-06-29 19:25 ` H.J. Lu
2022-06-29 19:32 ` Noah Goldstein
2022-06-29 22:11 ` Noah Goldstein
2022-06-28 15:27 ` [PATCH v1 3/3] x86: Add support for building {w}memset{_chk} with explicit ISA level Noah Goldstein
2022-06-29 19:30 ` H.J. Lu
2022-06-29 22:12 ` Noah Goldstein
2022-06-29 19:21 ` [PATCH v1 1/3] x86: Add definition for __wmemset_chk AVX2 RTM in ifunc impl list H.J. Lu
2022-06-29 23:08 ` Noah Goldstein
2022-07-14 3:03 ` Sunil Pandey
2022-06-29 22:12 ` [PATCH v2 " Noah Goldstein
2022-06-29 22:12 ` [PATCH v2 2/3] x86: Move and slightly improve memset_erms Noah Goldstein
2022-06-29 22:18 ` H.J. Lu
2022-06-29 23:09 ` Noah Goldstein
2022-06-29 22:12 ` [PATCH v2 3/3] x86: Add support for building {w}memset{_chk} with explicit ISA level Noah Goldstein
2022-06-29 22:53 ` H.J. Lu
2022-06-29 23:07 ` [PATCH v3 1/3] x86: Add definition for __wmemset_chk AVX2 RTM in ifunc impl list Noah Goldstein
2022-06-29 23:07 ` Noah Goldstein [this message]
2022-06-29 23:30 ` [PATCH v3 2/3] x86: Move and slightly improve memset_erms H.J. Lu
2022-07-14 3:04 ` Sunil Pandey
2022-06-29 23:07 ` [PATCH v3 3/3] x86: Add support for building {w}memset{_chk} with explicit ISA level Noah Goldstein
2022-06-29 23:28 ` H.J. Lu
2022-07-01 22:45 ` H.J. Lu
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20220629230706.1264225-2-goldstein.w.n@gmail.com \
--to=goldstein.w.n@gmail.com \
--cc=libc-alpha@sourceware.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).