Re: gcc3 vs 176.gcc

[Geoff Keating <geoffk at geoffk dot org>]

> From: Joe Buck <jbuck@synopsys.com>
> Date: Wed, 9 Jan 2002 15:44:37 -0800 (PST)
...
> > The problem is finding which expressions break the rules.  What I
> > expect will happen is that we can do a 90% solution, but the missing
> > 10% will vary by target and compiler revision---some things will work
> > on x86 with 3.1, some of those won't work on powerpc, and some won't
> > work with 3.2.  So you end up with a 70% or 30% or 5% solution.
> 
> I guess I'm still not seeing it: I would flag certain cases in the front
> end, where we are still back-end independent.  Then we only have to make
> sure that any annotations get preserved by the backends.
> 
> > A much better project, one which has been waiting for someone to do it
> > for some time and is universally agreed to be a good idea, is to have
> > the compiler warn in situations where it detects that the rules are
> > broken.
> 
> There are two ways of detecting it: based on offsets against registers
> (which would exist only in some back ends), or based on types of pointers
> closer to the source.  The latter type of check would work on all targets.

This sounds promising.  Would anyone like to propose a patch?

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