From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf1-x432.google.com (mail-pf1-x432.google.com [IPv6:2607:f8b0:4864:20::432]) by sourceware.org (Postfix) with ESMTPS id 1D3223858C53 for ; Fri, 21 Jul 2023 04:11:16 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 1D3223858C53 Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=gmail.com Received: by mail-pf1-x432.google.com with SMTP id d2e1a72fcca58-6726d5d92afso1809706b3a.1 for ; Thu, 20 Jul 2023 21:11:16 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20221208; t=1689912675; x=1690517475; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :from:to:cc:subject:date:message-id:reply-to; bh=U4tB1/w7d83cXd3nQPjlWJDuMNm6oWRp9b6/1ZXiMkc=; b=owDtWJ9lMi3mVRjaphFboZ4iWAAkzFhL5+2gFBTQtbHz9H4WQ+ArBDOMXjXlNRV8qB 6YuWCr9nkBG5qmKsIXUlSRt7nBxNqcUX1gyr/d7+02fMEvbsULLoUAImLf3ngCenlQT+ Lv/Wf/wqI2hnPP2ftm6cmQ2JWCTI398VzosicoECkDait/Xq/HSSWK8lV7dLCJ6EQCl/ 6cQpy81iVZ1FvoOvFx20a4qhmNk9KvMVZCKdU2FpajpVD1JleYDW+y5JTTZDfABWeSUn nVEN5B7BnlUYG+4G55vMb2+ZI/ZhpJUwWL0AkElwU0fU5d5AqGiuQGyd79MFQAQsHh5U Im/Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1689912675; x=1690517475; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=U4tB1/w7d83cXd3nQPjlWJDuMNm6oWRp9b6/1ZXiMkc=; b=F5Sys1EP4BrK77Bl0yufqw6+WuNIPReUH0UD5rSdvYKL02QcLWbdfYXFFSO4PdKuRG tcPU6/oRH+j4W8o3H1m3nkPbaJ8J25mVj8HWjIiSk49KgV+5VfAUjDhaV7RZ3AMfbhcH 14Wa3aLirucfO6XSQiBKA9AB90WfP7FY03cwMP8D4f7di9sZGjKTbOjZNB7rKmTpYJuC qxXPWLsMCmoPglx45q7zZipMSv+GooT3ALI1JDaBLbl5Eje8ABxWDOiPCFTDSekCn6gf Nzl00ta7K476cbM+oLXBeBQfAOy+0vOfRQWeRhsqmgmw+RkSat2XUw+4/sEp6lGYqd1t IxgA== X-Gm-Message-State: ABy/qLaoNXgRvoCQHrS39ED31NGPiL60MkKQqMb7PblYwywPleqMK0l8 CHdyIhydleOOo4KUCoqMgO8= X-Google-Smtp-Source: APBJJlEfvrMn0eLeAarWtJgwEOpTnKFiLz18HCPqMERjufGr2l7tvRwXKqyyHBEmeihlWvq7bp7/Iw== X-Received: by 2002:a05:6a20:6a11:b0:12e:caac:f263 with SMTP id p17-20020a056a206a1100b0012ecaacf263mr1260542pzk.20.1689912674598; Thu, 20 Jul 2023 21:11:14 -0700 (PDT) Received: from ?IPV6:2607:fb91:1de1:48f9:881c:2e2e:d043:d8aa? ([2607:fb91:1de1:48f9:881c:2e2e:d043:d8aa]) by smtp.gmail.com with ESMTPSA id fm10-20020a056a002f8a00b006783ee5df8asm1916895pfb.189.2023.07.20.21.11.12 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 20 Jul 2023 21:11:14 -0700 (PDT) Message-ID: <392d76fe-b3cd-f86d-c7d8-188149ca3e79@gmail.com> Date: Thu, 20 Jul 2023 22:11:10 -0600 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.12.0 Subject: Re: [PATCH v3] RISCV: Add -m(no)-omit-leaf-frame-pointer support. Content-Language: en-US To: Kito Cheng , yanzhang.wang@intel.com Cc: gcc-patches@gcc.gnu.org, juzhe.zhong@rivai.ai, kito.cheng@sifive.com, pan2.li@intel.com References: <20230602070726.3807539-1-yanzhang.wang@intel.com> <20230718074958.2806939-1-yanzhang.wang@intel.com> From: Jeff Law In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=-2.2 required=5.0 tests=BAYES_00,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FROM,NICE_REPLY_A,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 List-Id: On 7/20/23 21:49, Kito Cheng wrote: > LGTM, I think long jump is another issue and making ra become a fixed > register will escalate to an ABI issue, so that should not be a > blocker for this patch. I'll take a look tomorrow, but I'm supportive of what Yanzhang is trying to do in principle. I've got a few hot items to deal with tonight though. WRT making $ra fixed. In practice fixing a register just takes it out of the pool of things available to the allocator. Furthermore $ra is always considered clobbered at call sites. So while one could view it as an ABI change, it's not one that's actually observable in practice. I suspect that's one of the reasons why $ra is used by the assembler in this manner -- it minimizes both the ABI and performance impacts. jeff