[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <20130815014807.GU221@brightrain.aerifal.cx>
Date: Wed, 14 Aug 2013 21:48:07 -0400
From: Rich Felker <dalias@...ifal.cx>
To: musl@...ts.openwall.com
Subject: Re: Build system adjustments for subarchs
On Wed, Aug 14, 2013 at 07:55:25PM -0500, Strake wrote:
> On 13/08/2013, Rich Felker <dalias@...ifal.cx> 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
Powered by blists - more mailing lists
Confused about mailing lists and their use?
Read about mailing lists on Wikipedia
and check out these
guidelines on proper formatting of your messages.
