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DIR:OUT; SFP:1101; X-OriginatorOrg: arm.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 10 Feb 2022 14:25:56.7899 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 9a8acfda-0143-4e71-6363-08d9eca140a9 X-MS-Exchange-CrossTenant-Id: f34e5979-57d9-4aaa-ad4d-b122a662184d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=f34e5979-57d9-4aaa-ad4d-b122a662184d; Ip=[63.35.35.123]; Helo=[64aa7808-outbound-1.mta.getcheckrecipient.com] X-MS-Exchange-CrossTenant-AuthSource: AM5EUR03FT003.eop-EUR03.prod.protection.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: PR2PR08MB4923 X-Spam-Status: No, score=-6.0 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, RCVD_IN_DNSWL_NONE, RCVD_IN_MSPIKE_H2, SPF_HELO_PASS, SPF_PASS, TXREP, T_SCC_BODY_TEXT_LINE, UNPARSEABLE_RELAY autolearn=ham autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) 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: Thu, 10 Feb 2022 14:26:06 -0000 Hi,=0A= =0A= So as far as I can see the main justification for this is a specific issue = in some=0A= (one?) x86 microarchitecture. It's not clear to me that this will benefit o= ther=0A= targets enough to be worth the effort - again at best you avoid executing= =0A= one instruction per memset call. That was a big thing on in-order cores=0A= decades ago, but today that's hard to measure.=0A= =0A= Another issue is that unlike __memcmpeq, the default scenario is that most= =0A= targets will actually see a slowdown. Once compilers emit __memsetzero,=0A= one will be forced to provide an efficient target implementation just to=0A= avoid this slowdown. So I don't see how this helps improve GLIBC.=0A= =0A= Cheers,=0A= Wilco=