Re: Modes on CONST_INTs

[Geoff Keating <geoffk at geoffk dot org>]

> Date: Sun, 26 Nov 2000 15:19:43 +0100
> From: Hans-Peter Nilsson <hans-peter.nilsson@axis.com>
> CC: gcc@gcc.gnu.org, geoffk@geoffk.org
> 
> > Date: Fri, 24 Nov 2000 10:06:08 +0000 (GMT)
> > From: Bernd Schmidt <bernds@redhat.com>
> 
> > It seems that every now and then, we run into bugs involving a lack of mode
> > information on CONST_INTs.  So far everyone I've asked has agreed that we
> > really should have a mode for constants, but no one ever bothered because the
> > change is going to be huge.
> > 
> > Even if the change is going to be huge, I don't see how it can be any more
> > painful than the recurring problems we have because of the lack of mode
> > information.  So, I'm looking for viable ways to gradually transform the
> > compiler towards using modes on constants.
> 
> > Any comments?
> 
> Here's an "any-comment":
> 
> I was going in the direction of canonicalizing CONST_INTs by
> sign-extension, as indicated by Geoff in response to a recent
> patch of mine.  Perhaps that would solve those problems with a
> smaller change than caring for an associated mode with each
> constant; it doesn't seem like there are a large enough amount
> of failing codes and test-cases to warrant such a huge change.

These are orthogonal.  You still have to fix canonicalization
even if you have the mode information.  Having a mode may make this
easier; you can certainly find any bugs in the canonicalization much faster.

-- 
- Geoffrey Keating <geoffk@geoffk.org>