From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.org/gmane.linux.lib.musl.general/13394 Path: news.gmane.org!.POSTED!not-for-mail From: David Edelsohn Newsgroups: gmane.linux.lib.musl.general Subject: Re: [PATCH] PPC64 IEEE128 bit FP support Date: Fri, 2 Nov 2018 13:32:55 -0400 Message-ID: References: <20181026042829.GB28637@voyager> <20181026130119.GD3880@port70.net> <20181102161335.GL5150@brightrain.aerifal.cx> Reply-To: musl@lists.openwall.com NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" X-Trace: blaine.gmane.org 1541179876 13032 195.159.176.226 (2 Nov 2018 17:31:16 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Fri, 2 Nov 2018 17:31:16 +0000 (UTC) To: musl@lists.openwall.com Original-X-From: musl-return-13410-gllmg-musl=m.gmane.org@lists.openwall.com Fri Nov 02 18:31:12 2018 Return-path: Envelope-to: gllmg-musl@m.gmane.org Original-Received: from mother.openwall.net ([195.42.179.200]) by blaine.gmane.org with smtp (Exim 4.84_2) (envelope-from ) id 1gIdHs-0003JK-D1 for gllmg-musl@m.gmane.org; Fri, 02 Nov 2018 18:31:12 +0100 Original-Received: (qmail 21636 invoked by uid 550); 2 Nov 2018 17:33:21 -0000 Mailing-List: contact musl-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Original-Received: (qmail 21618 invoked from network); 2 Nov 2018 17:33:20 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to; bh=+f4SxTH805+ykG2neVVC9gscycM71djNrIjHHsbAXiI=; b=KVFKy/5tCjRjirOzwy02mt2TzViCGBr9T8yQiitlebV3HhKR5bQGgQa4bay8gDKftM bgJG1+9p/q2PB0Iy/FhLOiuWj9pjbtLUJenEe7ftgVHqSSDMwoGR7wg3P0h/Fsz8zcMo VtjIVorObxGwQgDOdLPsxZvcO5rTY6ZdZbRa0uv3VMo3D+enC+mDLree928lgvh0Cyc1 kO1W++mcswicKd8y3Obsc8kilNU1xBPC2O1+UohZhZdZYdyeF8F0Ry9+ou0h0M7WPkGs SF2ua7PMh7Ujby7haBEwfo2x79rDYgTx/dcPOBntW6gZIg0cyReUJ6KMvXwByt6Vz4eW jFGQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to; bh=+f4SxTH805+ykG2neVVC9gscycM71djNrIjHHsbAXiI=; b=h5vTI0OW86GWxFa0rLTP3SJvWQv49fFy+8XZESPPF2cVsZXaUS7cHo8iz/BUxxFlzC 3dUP3iohoAktOgNdcgBZrwTrtA8UU467NjVMRjZKKMdY32PVq+bAHGabAXYHtggYpDVu 6AbMcS5qkuS9Htcw3ehKWxMlWOuRGPZF9HdMRqDCnsYLJjKZcEs017+lW1gjmxe4hxHc gkmQb6iSs4PkofYgAsFD/qZ0Rm4W8N1impk7GbDJ3tczSRKP2VlBhMQN5xwCCer505D7 y5KsKUCZGZzXDJi1wJnh5o49VI4LFlYlwUxxZUWaj3XfBUWZxwI9b1x6Igk8QAHxcbi/ mgkA== X-Gm-Message-State: AGRZ1gKFQef2kQA0wz1tcXhiNSH6PdC4wn+gJENlHuiwc6EczoKEMc1s Zl6QZy4/MH7FkI0Il1a0Qn6BJQMykUle3Z9r6L4MRw== X-Google-Smtp-Source: AJdET5diZVG0CIHLJcHQtwNHrNNKFF9fxTu8j23dbA5FzNrGWbr/ppOiS2ppDACc+NJ6S36IGOmlsbpU3FxNwAGMMPA= X-Received: by 2002:a5d:6b4f:: with SMTP id x15-v6mr10658914wrw.304.1541179988471; Fri, 02 Nov 2018 10:33:08 -0700 (PDT) In-Reply-To: <20181102161335.GL5150@brightrain.aerifal.cx> Xref: news.gmane.org gmane.linux.lib.musl.general:13394 Archived-At: I don't believe that musl currently supports IBM double-double long double format, only IEEE 754 64 bit double precision as long double. IBM is working with other toolchains to support both the original double-double and the new 128 bit quad precision through compiler options, compiler macros, header definitions, and symbol compatibility in libraries. musl still would not support IBM double-double format. I don't know if it would be necessary for musl libc long double to be selectable for backward compatibility or one can implement a "flag day" where a musl libc release switches to only 128 bit quad precision long double. Thanks, David On Fri, Nov 2, 2018 at 12:13 PM Rich Felker wrote: > > On Fri, Oct 26, 2018 at 03:01:20PM +0200, Szabolcs Nagy wrote: > > * Markus Wichmann [2018-10-26 06:28:29 +0200]: > > > Now you just need to look through all the maths code to find all the > > > places that need changing. __floatscan() comes to mind immediately. And > > > I don't know if any of the libm functions needs adjustment for this new > > > format. > > > > generic c code in musl should work for all supported > > floating-point formats, which includes ieee binary128 > > for long double. > > > > only float.h needs to be set up according to the abi. > > > > some long double math functions don't have high quality > > implementations for ieee binary128 format though. > > Yes. Assuming there aren't other problems revealed by my questions > about argument passing and ISA levels, I think the only blocking issue > here is naming the ABI. I forgot to mention but that should also > involve a gcc patch that we can put in mcm and eventually upstream. > > QoI issues for IEEE-quad-based [sub]archs can be improved later; > aarch64 and s390x are already affected IIRC. > > Rich