From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.org/gmane.linux.lib.musl.general/3907 Path: news.gmane.org!not-for-mail From: Rich Felker Newsgroups: gmane.linux.lib.musl.general Subject: Re: Build system adjustments for subarchs Date: Wed, 14 Aug 2013 21:48:07 -0400 Message-ID: <20130815014807.GU221@brightrain.aerifal.cx> References: <20130814010617.GA16011@brightrain.aerifal.cx> Reply-To: musl@lists.openwall.com NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Trace: ger.gmane.org 1376531298 18474 80.91.229.3 (15 Aug 2013 01:48:18 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Thu, 15 Aug 2013 01:48:18 +0000 (UTC) To: musl@lists.openwall.com Original-X-From: musl-return-3911-gllmg-musl=m.gmane.org@lists.openwall.com Thu Aug 15 03:48:21 2013 Return-path: Envelope-to: gllmg-musl@plane.gmane.org Original-Received: from mother.openwall.net ([195.42.179.200]) by plane.gmane.org with smtp (Exim 4.69) (envelope-from ) id 1V9mfl-0007nb-0e for gllmg-musl@plane.gmane.org; Thu, 15 Aug 2013 03:48:21 +0200 Original-Received: (qmail 24236 invoked by uid 550); 15 Aug 2013 01:48:20 -0000 Mailing-List: contact musl-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: Original-Received: (qmail 24228 invoked from network); 15 Aug 2013 01:48:20 -0000 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Xref: news.gmane.org gmane.linux.lib.musl.general:3907 Archived-At: On Wed, Aug 14, 2013 at 07:55:25PM -0500, Strake wrote: > On 13/08/2013, Rich Felker wrote: > > The current system searches for arch-specific asm in this order: > > > > 1. $(ARCH)$(ASMSUBARCH)/%.s, where ASMSUBARCH for the default subarch > > is not blank but rather a unique suffix (for plain arm, it's "el"). > > This allows having asm that applies only to the default subarch but > > not others. > > > > 2. $(ARCH)/%.s, for shared asm used by all subarchs. > > > > 3. %.c, the C fallback (which is empty for code that cannot be > > implemented at all in C). > > Another option: > > Each arch has properties, which each take a value in a set; these sets > are mutually exclusive, and all the values in each set have the same > length. The properties have a well-defined order. The build system > parses each directory name as an arch name and a list of properties, > and chooses the most specific match; if no match, it uses the C code. This would be nice, but as far as I can tell there's no simple way of doing it without hard-coding the number of possible properties and including a rule for each one in the makefile. > > Unfortunately, this still provides no way to include asm that's used > > by both soft and hardfloat little-endian, or both little- and > > big-endian hardfloat, without having, for example: > > > > - armel/%.s and armhf/%.s as duplicate files or symlinked > > - armhf/%.s and armebhf/%.s as duplicate files or symlinked > > Thus arm would have 2 properties: > byte order ∈ { "eb", "el" } > float hardness ∈ { "hf", "sf" } > > asm used by both soft- and hard-float little-endian: armel/%.s > asm used by both little- and big-endian hard-float: armhf/%.s > asm used by little-endian hard-float: armelhf/%.s The system I ended up committing is not quite this logical, but it admits a simple implementation and it's very flexible, allowing arbitrary sharing and substitutions between subarchs. Rich