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[2620:52:3:1:0:246e:9693:128c]) by mx.google.com with ESMTPS id o21-20020a170906769500b00965a7a7c949si3391115ejm.364.2023.05.24.05.54.21 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 24 May 2023 05:54:21 -0700 (PDT) Received-SPF: pass (google.com: domain of gcc-patches-bounces+ouuuleilei=gmail.com@gcc.gnu.org designates 2620:52:3:1:0:246e:9693:128c as permitted sender) client-ip=2620:52:3:1:0:246e:9693:128c; Authentication-Results: mx.google.com; dkim=pass header.i=@gcc.gnu.org header.s=default header.b=vjr2Rorw; spf=pass (google.com: domain of gcc-patches-bounces+ouuuleilei=gmail.com@gcc.gnu.org designates 2620:52:3:1:0:246e:9693:128c as permitted sender) smtp.mailfrom="gcc-patches-bounces+ouuuleilei=gmail.com@gcc.gnu.org"; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=gnu.org Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id 23C763858004 for ; Wed, 24 May 2023 12:54:20 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 23C763858004 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org; s=default; t=1684932860; bh=2xQRchEI4rbOnCrykoDDTfWdWEY7u8L8MpjtcnW1DpE=; h=To:Cc:Subject:Date:List-Id:List-Unsubscribe:List-Archive: List-Post:List-Help:List-Subscribe:From:Reply-To:From; b=vjr2RorwV35hsatsQfxTPaBk2q/cA0hv5jzWafGo8eormiUO9W9HytynUIsYedVqa kvJ+/2mL4sjTYTP6tJmUq14NbgQ7U6grnLuQyv3ZBDgq4QldQOZhO8Zbg79GPNZqeP m2GNgZjCAervOGbHW4CMD/pPKdUucAMHJTikJX2E= X-Original-To: gcc-patches@gcc.gnu.org Delivered-To: gcc-patches@gcc.gnu.org Received: from mail.ispras.ru (mail.ispras.ru [83.149.199.84]) by sourceware.org (Postfix) with ESMTPS id 54C6F3858CDB for ; Wed, 24 May 2023 12:53:37 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 54C6F3858CDB Received: from localhost.intra.ispras.ru (unknown [10.10.3.121]) by mail.ispras.ru (Postfix) with ESMTP id 3F67940737C0; Wed, 24 May 2023 12:53:34 +0000 (UTC) DKIM-Filter: OpenDKIM Filter v2.11.0 mail.ispras.ru 3F67940737C0 To: gcc-patches@gcc.gnu.org Cc: Alexander Monakov Subject: [PATCH] doc: clarify semantics of vector bitwise shifts Date: Wed, 24 May 2023 15:53:32 +0300 Message-Id: <20230524125332.30839-1-amonakov@ispras.ru> X-Mailer: git-send-email 2.32.0 MIME-Version: 1.0 X-Spam-Status: No, score=-9.4 required=5.0 tests=BAYES_00, GIT_PATCH_0, KAM_DMARC_STATUS, 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: gcc-patches@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-Patchwork-Original-From: Alexander Monakov via Gcc-patches From: Alexander Monakov Reply-To: Alexander Monakov Errors-To: gcc-patches-bounces+ouuuleilei=gmail.com@gcc.gnu.org Sender: "Gcc-patches" X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1766780160383406280?= X-GMAIL-MSGID: =?utf-8?q?1766780160383406280?= Explicitly say that bitwise shifts for narrow types work similar to element-wise C shifts with integer promotions, which coincides with OpenCL semantics. gcc/ChangeLog: * doc/extend.texi (Vector Extensions): Clarify bitwise shift semantics. --- gcc/doc/extend.texi | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi index e426a2eb7d..6b4e94b6a1 100644 --- a/gcc/doc/extend.texi +++ b/gcc/doc/extend.texi @@ -12026,7 +12026,12 @@ elements in the operand. It is possible to use shifting operators @code{<<}, @code{>>} on integer-type vectors. The operation is defined as following: @code{@{a0, a1, @dots{}, an@} >> @{b0, b1, @dots{}, bn@} == @{a0 >> b0, a1 >> b1, -@dots{}, an >> bn@}}@. Vector operands must have the same number of +@dots{}, an >> bn@}}@. When the base type is narrower than @code{int}, +element-wise shifts are performed as if operands underwent C integer +promotions, like in OpenCL. This makes vector shifts by up to 31 bits +well-defined for vectors with @code{char} and @code{short} base types. + +Operands of binary vector operations must have the same number of elements. For convenience, it is allowed to use a binary vector operation