From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pj1-x102d.google.com (mail-pj1-x102d.google.com [IPv6:2607:f8b0:4864:20::102d]) by sourceware.org (Postfix) with ESMTPS id 5CC0B3854160 for ; Wed, 29 Jun 2022 19:26:34 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 5CC0B3854160 Received: by mail-pj1-x102d.google.com with SMTP id 73-20020a17090a0fcf00b001eaee69f600so443594pjz.1 for ; Wed, 29 Jun 2022 12:26:34 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=bYPRo6i/z0jHZdIEMwZ5I3Xmtn1waiLzTawFpVJli2U=; b=oEZQY0lWN6YoPu0vubL04b5BwIKqblyP9esTCyz5CTrKLnQXWD3J8ri+MJllt0Q6lI YZzHYq81/OAtmoUh+9B6OwroEsMb5lET07Qfp+XejekJjnugBG3NUFRvDt3DKhNsyg5c HxU6sl6NWe74sDlnivd0SV4uGXOPwDuX4ipK9k0Ky2I6+iUcGvmLiT8KKun2hD4wyolQ SRdYbFQKtzywBKVGzak7slkLffbypZ3zieF+2NxZSKuVaT6OiW5kXixlr8ZSM3qh8czS PJ4GQSsCljs4U0AO49yxc+MqnzC3wdipu1j/TWFh+YJxJpvHTFHmdwUD3fETDLDZTiUU QMCQ== X-Gm-Message-State: AJIora+gh78s54OnUlrO+qWN5htJWHyJUdSGbB+o7Nf/mCN/5+NrDo37 CnousHnG7RE5bCL7g8mrYw03TXh4yiG1Q3EVXnc= X-Google-Smtp-Source: AGRyM1shNpZ2VQSg9fgzVbMx47OJLIA1W/RC0cTzO/6q/gBSujE86yYreWNiH4TmdmxAKL8LpKrbmX9WbCybYgSnFAM= X-Received: by 2002:a17:90a:e413:b0:1ec:8952:cc5d with SMTP id hv19-20020a17090ae41300b001ec8952cc5dmr7284125pjb.101.1656530793427; Wed, 29 Jun 2022 12:26:33 -0700 (PDT) MIME-Version: 1.0 References: <20220628152735.17863-1-goldstein.w.n@gmail.com> <20220628152735.17863-2-goldstein.w.n@gmail.com> In-Reply-To: <20220628152735.17863-2-goldstein.w.n@gmail.com> From: "H.J. Lu" Date: Wed, 29 Jun 2022 12:25:57 -0700 Message-ID: Subject: Re: [PATCH v1 2/3] x86: Move and slightly improve memset_erms To: Noah Goldstein Cc: GNU C Library , "Carlos O'Donell" Content-Type: text/plain; charset="UTF-8" X-Spam-Status: No, score=-3024.8 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-List-Received-Date: Wed, 29 Jun 2022 19:26:36 -0000 On Tue, Jun 28, 2022 at 8:27 AM Noah Goldstein wrote: > > 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 L(memset_{chk}_erms) to its own file. Leaving it in between the It is ENTRY, not L. Did you mean to move them to the end of file? > memset_{impl}_unaligned both adds unnecessary complexity to the > file and wastes space in a relatively hot cache section. > --- > .../multiarch/memset-vec-unaligned-erms.S | 54 ++++++++----------- > 1 file changed, 23 insertions(+), 31 deletions(-) > > diff --git a/sysdeps/x86_64/multiarch/memset-vec-unaligned-erms.S b/sysdeps/x86_64/multiarch/memset-vec-unaligned-erms.S > index abc12d9cda..d98c613651 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 > @@ -461,3 +430,26 @@ L(between_2_3): > #endif > ret > END (MEMSET_SYMBOL (__memset, unaligned_erms)) > + > +#if defined USE_MULTIARCH && IS_IN (libc) && 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 > + 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 > -- > 2.34.1 > -- H.J.