From patchwork Wed Jun 7 02:31:47 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lulu Cheng X-Patchwork-Id: 70693 Return-Path: X-Original-To: patchwork@sourceware.org Delivered-To: patchwork@sourceware.org Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id CFFCD3857341 for ; Wed, 7 Jun 2023 02:32:33 +0000 (GMT) X-Original-To: gcc-patches@gcc.gnu.org Delivered-To: gcc-patches@gcc.gnu.org Received: from eggs.gnu.org (eggs.gnu.org [IPv6:2001:470:142:3::10]) by sourceware.org (Postfix) with ESMTPS id 7A7AC3858C54 for ; Wed, 7 Jun 2023 02:32:15 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 7A7AC3858C54 Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=loongson.cn Authentication-Results: sourceware.org; spf=fail smtp.mailfrom=loongson.cn Received: from mail.loongson.cn ([114.242.206.163]) by eggs.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1q6iy4-0007Gj-1u for gcc-patches@gcc.gnu.org; Tue, 06 Jun 2023 22:32:15 -0400 Received: from loongson.cn (unknown [10.2.5.5]) by gateway (Coremail) with SMTP id _____8Bx3ukb7H9koQEAAA--.67S3; Wed, 07 Jun 2023 10:31:56 +0800 (CST) Received: from 5.5.5 (unknown [10.2.5.5]) by localhost.localdomain (Coremail) with SMTP id AQAAf8DxbMoX7H9k56YDAA--.5211S2; Wed, 07 Jun 2023 10:31:55 +0800 (CST) From: Lulu Cheng To: gcc-patches@gcc.gnu.org Cc: xry111@xry111.site, i@xen0n.name, xuchenghua@loongson.cn, Lulu Cheng Subject: [PATCH] LoongArch: Change jumptable's register constraint to 'q' [PR110136] Date: Wed, 7 Jun 2023 10:31:47 +0800 Message-Id: <20230607023147.1602812-1-chenglulu@loongson.cn> X-Mailer: git-send-email 2.31.1 MIME-Version: 1.0 X-CM-TRANSID: AQAAf8DxbMoX7H9k56YDAA--.5211S2 X-CM-SenderInfo: xfkh0wpoxo3qxorr0wxvrqhubq/ X-Coremail-Antispam: 1Uk129KBj9xXoWrZw1DAw18XFWfAw4DGw4fCrX_yoWDZrc_Ww 4ft3WDGrWjkayvqw4qgFWFyryUWF1kG3WavFyDXF4IyFyrXrsIyrZrZ3WrAw15KrZxAFsx Ar4kKrnIkrn2vosvyTuYvTs0mTUanT9S1TB71UUUUUDqnTZGkaVYY2UrUUUUj1kv1TuYvT s0mT0YCTnIWjqI5I8CrVACY4xI64kE6c02F40Ex7xfYxn0WfASr-VFAUDa7-sFnT9fnUUI cSsGvfJTRUUUb7kYFVCjjxCrM7AC8VAFwI0_Jr0_Gr1l1xkIjI8I6I8E6xAIw20EY4v20x vaj40_Wr0E3s1l1IIY67AEw4v_Jrv_JF1l8cAvFVAK0II2c7xJM28CjxkF64kEwVA0rcxS w2x7M28EF7xvwVC0I7IYx2IY67AKxVW8JVW5JwA2z4x0Y4vE2Ix0cI8IcVCY1x0267AKxV W8JVWxJwA2z4x0Y4vEx4A2jsIE14v26F4j6r4UJwA2z4x0Y4vEx4A2jsIEc7CjxVAFwI0_ Gr1j6F4UJwAS0I0E0xvYzxvE52x082IY62kv0487Mc804VCY07AIYIkI8VC2zVCFFI0UMc 02F40EFcxC0VAKzVAqx4xG6I80ewAv7VC0I7IYx2IY67AKxVWUXVWUAwAv7VC2z280aVAF wI0_Jr0_Gr1lOx8S6xCaFVCjc4AY6r1j6r4UM4x0Y48IcxkI7VAKI48JMxAIw28IcxkI7V AKI48JMxC20s026xCaFVCjc4AY6r1j6r4UMI8I3I0E5I8CrVAFwI0_Jr0_Jr4lx2IqxVCj r7xvwVAFwI0_JrI_JrWlx4CE17CEb7AF67AKxVWUAVWUtwCIc40Y0x0EwIxGrwCI42IY6x IIjxv20xvE14v26r1j6r1xMIIF0xvE2Ix0cI8IcVCY1x0267AKxVWUJVW8JwCI42IY6xAI w20EY4v20xvaj40_Jr0_JF4lIxAIcVC2z280aVAFwI0_Jr0_Gr1lIxAIcVC2z280aVCY1x 0267AKxVWUJVW8JbIYCTnIWIevJa73UjIFyTuYvjxU7_MaUUUUU Received-SPF: pass client-ip=114.242.206.163; envelope-from=chenglulu@loongson.cn; helo=mail.loongson.cn X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-Spam-Status: No, score=-15.8 required=5.0 tests=BAYES_00, GIT_PATCH_0, KAM_DMARC_STATUS, SPF_FAIL, SPF_HELO_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: , Errors-To: gcc-patches-bounces+patchwork=sourceware.org@gcc.gnu.org Sender: "Gcc-patches" If the $ra register is modified during the jump to the jump table, the hardware branch prediction function will be broken, resulting in a significant increase in the branch false prediction rate and affecting performance. gcc/ChangeLog: * config/loongarch/loongarch.md: Change register constraint to 'q'. --- gcc/config/loongarch/loongarch.md | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/gcc/config/loongarch/loongarch.md b/gcc/config/loongarch/loongarch.md index 816a943d155..f9b64173104 100644 --- a/gcc/config/loongarch/loongarch.md +++ b/gcc/config/loongarch/loongarch.md @@ -2926,9 +2926,11 @@ (define_expand "tablejump" DONE; }) +;; Jump to the jump table Avoid using the $r1 register to prevent +;; affecting hardware branch prediction. (define_insn "@tablejump" [(set (pc) - (match_operand:P 0 "register_operand" "r")) + (match_operand:P 0 "register_operand" "q")) (use (label_ref (match_operand 1 "" "")))] "" "jr\t%0"