From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-yb1-xb2f.google.com (mail-yb1-xb2f.google.com [IPv6:2607:f8b0:4864:20::b2f]) by sourceware.org (Postfix) with ESMTPS id 9123B3858D32 for ; Sun, 22 Jan 2023 15:45:15 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 9123B3858D32 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-yb1-xb2f.google.com with SMTP id p141so9347927ybg.12 for ; Sun, 22 Jan 2023 07:45:15 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:from:to:cc:subject:date:message-id:reply-to; bh=WgCeJCQiQ7LkGrUd4Wz1MxJPRujzwXRW4omGNmXux2Y=; b=chB6DspN35g9MHXhkiLepObvOwvz+sBh8UNrmKeakIJwwVc+OORGUdlJhdSOJ7+/M6 xTbz4C97yWW2kXs5yrpJr8YygVWUiCrNTP9uQtf+GFsgyOJNM9CaeN9cx3LM5dUJzqsZ pyiGV46kbD1wzCk7+pZ5DPLWDqoou63VM/jN10x/fQi4PiLvR/ldjWaWTXeloFP6MRnr NyvuppDNN4W5DGaSzm37nmw5zm7PxCETZXL50JbKBMstqB5z5gNGQPkTyGDAepZQodub +UMxIE8HZ9Tb5TcTDP/enmtigyQN/8yOVQ2CF6kUgUgEtJZ5FgxH7wddurPa1vpXlbJq tx2w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=WgCeJCQiQ7LkGrUd4Wz1MxJPRujzwXRW4omGNmXux2Y=; b=Qykk8ajQciewB2XnV+Kdmtih9lgQKyEz/nMyavSzoSgnkvhjCtRDVRlX9wBsAkHrc1 doEyEqwVmmGothpRWR68Vq8EhpFQD5TRzlDycC28K8l24jqWItTemURb3WLfN0b6K0A2 DF2l642/FBvBcMQwje79EVh99AlSGM30n989MIEWR2fwHMqdhLvcL3EWKWdxgNCHSqM/ cBO/N6kVj61LhGqJAj6ZLSa8q3xWIs/5uklsGKLmtB7mb3kma5o01/IRaMZiP5htjzIx 7pQpW8zasuF25Sqqs7+o1ftz2wkL8eMIP0YRgSjoaYM3dpaDwE7VM6hyq3LM7FWl1mN2 ztBA== X-Gm-Message-State: AFqh2krYBsbDw79Y/xgVe1kCSnUmJBLZsDwygAOmJGVjcAhlW9Rotwti 5e36r/QAqr94XbeKw/SMaIdQ/Tn3K935PgGt3Ys= X-Google-Smtp-Source: AMrXdXv3FA7cZzoqYtXJCY2Z+kRbBJ+wCpMlTtuuJ5l1nir6PwI/6WFlTl7p5Q3wik1V20OiRKt8qVcoqiY1aXW2Wcg= X-Received: by 2002:a25:1189:0:b0:6d5:a304:b9cf with SMTP id 131-20020a251189000000b006d5a304b9cfmr2937000ybr.293.1674402314933; Sun, 22 Jan 2023 07:45:14 -0800 (PST) MIME-Version: 1.0 References: <465b0cbe-73ca-f5a0-661d-d34217e29b4d.ref@yahoo.co.jp> <465b0cbe-73ca-f5a0-661d-d34217e29b4d@yahoo.co.jp> In-Reply-To: From: Max Filippov Date: Sun, 22 Jan 2023 07:45:03 -0800 Message-ID: Subject: Re: [PATCH v4] xtensa: Eliminate the use of callee-saved register that saves and restores only once To: "Takayuki 'January June' Suwa" Cc: GCC Patches Content-Type: text/plain; charset="UTF-8" X-Spam-Status: No, score=0.5 required=5.0 tests=BAYES_00,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FROM,FROM_LOCAL_NOVOWEL,HK_RANDOM_ENVFROM,HK_RANDOM_FROM,RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_PASS,TXREP autolearn=no 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 Fri, Jan 20, 2023 at 8:39 PM Takayuki 'January June' Suwa wrote: > On 2023/01/21 0:14, Max Filippov wrote: > > After having this many attempts and getting to the issues that are > > really hard to detect I wonder if the target backend is the right place > > for this optimization? > > > I guess they are not hard to detect I mean, on the testing side. check-gcc testsuite passed without new regressions with this change, linux kernel smoke test passed, I was almost convinced that it's ok to commit. > but just issues I didn't anticipate (and I just need a little more work). Looking at other peephole2 patterns I see that their code transformations are much more compact and they don't need to track additional properties of unrelated instructions. > And where else should it be done? What about implementing a > target-specific pass just for one-point optimization? I don't even understand what's target-specific in this optimization? It looks very generic to me. -- Thanks. -- Max