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([192.55.60.43]) by smtp.gmail.com with ESMTPSA id k11-20020a6555cb000000b0040d87299ca3sm11638782pgs.54.2022.06.29.15.12.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 29 Jun 2022 15:12:08 -0700 (PDT) To: libc-alpha@sourceware.org Subject: [PATCH v2 2/3] x86: Move and slightly improve memset_erms Date: Wed, 29 Jun 2022 15:12:03 -0700 Message-Id: <20220629221204.1242709-2-goldstein.w.n@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220629221204.1242709-1-goldstein.w.n@gmail.com> References: <20220628152735.17863-1-goldstein.w.n@gmail.com> <20220629221204.1242709-1-goldstein.w.n@gmail.com> MIME-Version: 1.0 X-Spam-Status: No, score=-12.1 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, FREEMAIL_FROM, GIT_PATCH_0, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-Patchwork-Original-From: Noah Goldstein via Libc-alpha From: Noah Goldstein Reply-To: Noah Goldstein Errors-To: libc-alpha-bounces+patchwork=sourceware.org@sourceware.org Sender: "Libc-alpha" 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 | 25 +++++++++++++++ .../multiarch/memset-vec-unaligned-erms.S | 31 ------------------- 3 files changed, 26 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..1fce0c9fcc --- /dev/null +++ b/sysdeps/x86_64/multiarch/memset-erms.S @@ -0,0 +1,25 @@ +#include + +#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