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From: rfg@ics.uci.edu (Ron Guilmette)
Newsgroups: gnu.gcc
Subject: Re: short jumps
Keywords: port
Message-ID: <25CA909C.21229@paris.ics.uci.edu>
Date: 3 Feb 90 08:04:44 GMT
References: <1049@tuvie>
Reply-To: rfg@ics.uci.edu (Ron Guilmette)
Organization: UC Irvine Department of ICS
Lines: 15

In article <1049@tuvie> inst182@tuvie (Inst.f.Techn.Informatik) writes:
>
>I want to make a port of gcc to a new processor that has short relative
>jumps for up to +-128 instructions. Now my problem is the following:
>
>This jump has completely different semantics than a far jump. How can I
>check if I can use the short jump instead of a far jump. I cannot delay
>the decision till assembly time, so I *MUST* have gcc emit the right 
>instruction. *ANY* hints will be appreciated.

Why can't you "dealy the decision till assembly time"?  I believe that at
least some assemblers (e.g. for ns32k) optimize long jumps into short ones
where they find that it is possible and legal to do.

// rfg