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Re: Adding constants to LO_SUM
- To: kenner at vlsi1 dot ultra dot nyu dot edu (Richard Kenner)
- Subject: Re: Adding constants to LO_SUM
- From: law at redhat dot com
- Date: Mon, 09 Jul 2001 13:33:24 -0600
- cc: geoffk at geoffk dot org, gcc-patches at gcc dot gnu dot org
- Reply-To: law at redhat dot com
In message <10107091923.AA07025@vlsi1.ultra.nyu.edu>you write:
> This might fix the problem, but it isn't correct. Just because it
> happens to work on rs6000 for 'long long', it doesn't follow it'll
> work everywhere. It is an inherently target-dependent thing, because
> LO_SUM is a target-dependent thing.
> I'm not certain what "correct" mean in this context, since there's no
> sufficiently-detailed definition of LO_SUM around. However, this
> essentially restores the old behavior and so seems as "correct" as the
> old code was.
> Do you have any other suggestions?
In simplest terms, you can't assume you can add any constant to a LO_SUM
term. It's simply not safe to do so in generic routines.