From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) by sourceware.org (Postfix) with ESMTP id 723E43858C00 for ; Wed, 7 Sep 2022 20:57:23 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 723E43858C00 Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=kernel.crashing.org Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=kernel.crashing.org Received: from gate.crashing.org (localhost.localdomain [127.0.0.1]) by gate.crashing.org (8.14.1/8.14.1) with ESMTP id 287KuMCm030171; Wed, 7 Sep 2022 15:56:22 -0500 Received: (from segher@localhost) by gate.crashing.org (8.14.1/8.14.1/Submit) id 287KuMJQ030170; Wed, 7 Sep 2022 15:56:22 -0500 X-Authentication-Warning: gate.crashing.org: segher set sender to segher@kernel.crashing.org using -f Date: Wed, 7 Sep 2022 15:56:21 -0500 From: Segher Boessenkool To: Michael Meissner , gcc-patches@gcc.gnu.org, "Kewen.Lin" , David Edelsohn , Peter Bergner , Will Schmidt Subject: Re: [PATCH] Improve converting between 128-bit modes that use the same format Message-ID: <20220907205621.GL25951@gate.crashing.org> References: <20220823211345.GW25951@gate.crashing.org> <20220906222211.GH25951@gate.crashing.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.2.3i X-Spam-Status: No, score=-3.1 required=5.0 tests=BAYES_00,JMQ_SPF_NEUTRAL,KAM_DMARC_STATUS,SPF_HELO_PASS,SPF_PASS,TXREP,T_SCC_BODY_TEXT_LINE 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 Wed, Sep 07, 2022 at 04:25:49PM -0400, Michael Meissner wrote: > On Tue, Sep 06, 2022 at 05:22:11PM -0500, Segher Boessenkool wrote: > > Please do this. It is the biggest problem I have with most of your > > patches: you seem to save up development of a week, and then send it out > > as big omnibus patch an hour or two before my weekend. This is not > > ideal. > > This is always going to be the case. As I'm developing the larger patches, > there are usually at least 3 smaller problems wanting to get out. I don't know > what these things are until I run into them. This is the only large problem. Humongous, if you want. It has been _the_ problem since the beginning of the IEEE QP work. None of this is news to anyone. It makes all other problems tens of times as hard to solve. The other thing that would have made development way way way less work in total, and much simpler, is supporting this on more systems. Everything with VMX for example (with the exact same ABI as we have now!), or just a la "nof" ("-msoft-float"), which is easy to so as well. You end up testing more cases, "having" to test more cases, *but* there are way fewer exceptions. Anything downstream from us (essentially everything, we are the C and C++ compilers after all) has to do a lot of unnecessary work as well, because of this. But the fundamental problem that IEEE QP and double-double can not be ordered causes so many problems it is just not funny. The *workarounds* for it each cause a cascade of *other problems*, and there is no end in sight. Segher