Path: utzoo!telly!attcan!uunet!mcsun!tuvie!inst182
From: inst182@tuvie (Inst.f.Techn.Informatik)
Newsgroups: gnu.gcc
Subject: Re: short jumps
Keywords: port
Message-ID: <1086@tuvie>
Date: 7 Feb 90 13:56:43 GMT
References: <1049@tuvie> <25CA909C.21229@paris.ics.uci.edu> <1051@tuvie> <47277@lll-winken.LLNL.GOV>
Reply-To: inst182@tuvie.UUCP (Inst.f.Techn.Informatik)
Organization: Technical University of Vienna, EDP-Center
Lines: 31

In article <47277@lll-winken.LLNL.GOV> casey@gauss.llnl.gov (Casey Leedom) writes:
>Instead Mips' assembler has virtual instructions for things
>like ``jump foo'', ``load reg,foo'', etc. and it generates the right
>sequences.
>
> Thus,
>it doesn't cost that much to allocate a register out of the register set
>for an assembler temporary and it costs a lot in effort not to do it that
>way.
>
>Casey

Now this of course would mean that the assembler would have to be much
more intelligent. Now we have a very simple two-pass assembler that
counts insntructions in the first pass and assigns values to labels and in the
second pass it emits code. Obviously, if some instructions have variable
length, this is no longer possible. Now my problem is: how much work is
it to build an assembler which can handle instructions whose length
cannot be evaluated in the first pass? Is there any documentation
describing how to port gas? (By the way, is there any documentation at
all for gas? If so, where can I get it?)

				Thanx in advance,

					mike
       ____  ____
      /   / / / /   Michael K. Gschwind             mike@vlsivie.at
     /   / / / /    Institute for VLSI-Design       mike@vlsivie.uucp
     ---/           Technical University, Vienna 
       / 
   ___/