From mboxrd@z Thu Jan  1 00:00:00 1970
From: peter.jeremy@alcatel.com.au (Peter Jeremy)
Date: Fri, 15 Feb 2002 14:08:29 +1100
Subject: [TUHS] Re: Porting Unix v6 to i386
In-Reply-To: <20020214143050.J241@goldberry.poofy.goof.com>; from
 agrier@poofygoof.com on Thu, Feb 14, 2002 at 02:30:50PM -0800
References: <no.id@cim.alcatel.com.au>
 <20020214143050.J241@goldberry.poofy.goof.com>
Message-ID: <20020215140829.G78085@gsmx07.alcatel.com.au>

On 2002-Feb-14 14:30:50 -0800, "Aaron J. Grier" <agrier at poofygoof.com> wrote:
>support for PDP-11 was added to gcc a few months ago.  I don't think
>it's been well tested, but support exists in current versions of
>binutils and gcc.
>
>http://pdp11.nocrew.org/
>
>there's also support for the m68hc11/12 which are 16-bit.

This is only cross-compilation support.  gcc was never designed to be
hosted in a 16-bit environment.  An i386 gcc is:
   text    data     bss     dec     hex filename
1660236   22836   97104 1780176  1b29d0 /usr/libexec/cc1

Even taking into account the savings with 16-bit int's and pointers,
you won't get the data segment below 64k - and most of gcc's structures
are dynamically allocated.

>it seems like support for 80{,1,2}86 in gcc should be possible; it just
>hasn't been done yet.

Given that i386 is already supported, adding support for 16-bit x86
would be fairly easy.  The only major work would be handling the
16-bit addressing modes.

>another compiler that might be worth looking at is SDCC
>http://sdcc.sourceforge.net/ which is currently targeted towards 8-bit
>MCUs.

Again, no x86 support and I don't believe the code generation is
that good.

>of course bootstrapping via the original K&R compiler would be the
>"classic" way to do it, though.  ;)

The PDP-11 is orthogonal and so PCC doesn't have to worry about
getting particular operands into particular registers.  I suspect
that supporting the i386's idiosyncracies would be non-trivial.

Peter