From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on inbox.vuxu.org X-Spam-Level: X-Spam-Status: No, score=-0.9 required=5.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FROM,MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED, RCVD_IN_MSPIKE_H3,RCVD_IN_MSPIKE_WL,SUSPICIOUS_RECIPS autolearn=ham autolearn_force=no version=3.4.2 Received: (qmail 23778 invoked from network); 22 Apr 2020 06:32:03 -0000 Received: from mother.openwall.net (195.42.179.200) by inbox.vuxu.org with UTF8ESMTPZ; 22 Apr 2020 06:32:03 -0000 Received: (qmail 23604 invoked by uid 550); 22 Apr 2020 06:32:01 -0000 Mailing-List: contact musl-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Reply-To: musl@lists.openwall.com Received: (qmail 23583 invoked from network); 22 Apr 2020 06:32:00 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:subject:to:cc:references:in-reply-to:mime-version :message-id:content-transfer-encoding; bh=Yvs+jDMlztJFPt5LzfczyrUzcW5qABLRNQxvKGI4VrM=; b=M5wgX8o3tW2GHJyD1APO0kyeeywMQvwgTA9EPixbd9OdbrzKptK1e8tsM8U8H0Nasp SaljzHJnrnvV3+315c3Y0BaLx6asMU8hgmPFZIZddy/sDuuBiiYBGnpVaPD6dZIkBVMW L5QRNXZmEweq4uee1SSbVV0E4j2kjvDnVThP2nBR/KL2PE54lAxbG0abcoIwAfp3vfM2 oO3vQ06IbjfnbE8OI5JcSw6UxTXtY7gT4ajkw33S3fgoJe7fy5TblxcqjAYkLx/AsNO/ Zd0+yx/Tp/69UmThoy6OSNFJLsDzylQAKporJlk2DpfUkGrIXPi1FfmmB10jj0htyJWt GstA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:subject:to:cc:references:in-reply-to :mime-version:message-id:content-transfer-encoding; bh=Yvs+jDMlztJFPt5LzfczyrUzcW5qABLRNQxvKGI4VrM=; b=p5kr4/OBTzRa02wgYogRtmXaUw+Uy//vx3wFutge+27xJKO0GXr3WjUTdfM4nggHdA RSxy69UTi/R68rF0GU9zRyyPsY5KvWwGTNLLvWiUifmfJB3WH/jF1W2sKb1PugL7+5W7 72WzX9zqpX727WGaCMRzNkBToM2jhR8dMvWj5V1EpCS0aJwwzsJ/r2HWu6dtKF23Rc49 hKdvnoXtpK2c6mYNmSjS2g69MVq6smxylFhEUk9xZkNB7ECpgvMDmsSWzf0kQ+P3ic0Z raMMGnWDFje/v+jOegqDzMXpL9cZ/miART5dSeo00QIJ0ycIMuhvUZLZalDvBt/cbijN 3VKg== X-Gm-Message-State: AGi0PuZTX90lyGrbd3DoOGONhN479QUQ4CKKAbvvOje1zQ7HDoQyXuB7 Bly3BQycsDQiGR/OjOwU28Bt0t4d X-Google-Smtp-Source: APiQypKuGcETuyIq4RG/HZlsaI7LvJV6ngILV0Zr6Un5OwN9MLfxRx6PweQUn2wRwKHWETGX/t9f7w== X-Received: by 2002:a17:90a:4ce5:: with SMTP id k92mr687845pjh.192.1587537108752; Tue, 21 Apr 2020 23:31:48 -0700 (PDT) Date: Wed, 22 Apr 2020 16:29:19 +1000 From: Nicholas Piggin To: Rich Felker Cc: Adhemerval Zanella , libc-alpha@sourceware.org, libc-dev@lists.llvm.org, linuxppc-dev@lists.ozlabs.org, musl@lists.openwall.com References: <20200416153756.GU11469@brightrain.aerifal.cx> <4b2a7a56-dd2b-1863-50e5-2f4cdbeef47c@linaro.org> <20200416175932.GZ11469@brightrain.aerifal.cx> <4f824a37-e660-8912-25aa-fde88d4b79f3@linaro.org> <20200416183151.GA11469@brightrain.aerifal.cx> <1587344003.daumxvs1kh.astroid@bobo.none> <20200420013412.GZ11469@brightrain.aerifal.cx> <1587348538.l1ioqml73m.astroid@bobo.none> <20200420040926.GA11469@brightrain.aerifal.cx> <1587356128.aslvdnmtbw.astroid@bobo.none> <20200420172715.GC11469@brightrain.aerifal.cx> <1587531042.1qvc287tsc.astroid@bobo.none> In-Reply-To: <1587531042.1qvc287tsc.astroid@bobo.none> MIME-Version: 1.0 Message-Id: <1587536847.k87ypbo53k.astroid@bobo.none> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Subject: Re: [musl] Powerpc Linux 'scv' system call ABI proposal take 2 Excerpts from Nicholas Piggin's message of April 22, 2020 4:18 pm: > If we go further and try to preserve r3 as well by putting the return=20 > value in r9 or r0, we go backwards about 300 bytes. It's good for the=20 > lock loops and complex functions, but hurts a lot of simpler functions=20 > that have to add 'mr r3,r9' etc. =20 >=20 > Most of the time there are saved non-volatile GPRs around anyway though,=20 > so not sure which way to go on this. Text size savings can't be ignored > and it's pretty easy for the kernel to do (we already save r3-r8 and > zero them on exit, so we could load them instead from cache line that's > should be hot). >=20 > So I may be inclined to go this way, even if we won't see benefit now. By, "this way" I don't mean r9 or r0 return value (which is larger code), but r3 return value with r0,r4-r8 preserved. Thanks, Nick