From: Jeffrey A Law <law@cygnus.com>
To: John Carr <jfc@mit.edu>
Cc: Richard Henderson <rth@cygnus.com>, egcs@cygnus.com
Subject: Re: memrefs_conflict_p omission?
Date: Tue, 07 Oct 1997 23:14:00 -0000 [thread overview]
Message-ID: <6275.876264736@hurl.cygnus.com> (raw)
In-Reply-To: <199710061344.JAA24923@no-knife.MIT.EDU>
In message < 199710061344.JAA24923@no-knife.MIT.EDU >you write:
>
> > Something that came to mind a bit ago while fixing AND nonsense,
> > was that perhaps this was an omission?
>
> That code came from sched.c and I don't think I changed it (at least
> not in the final version -- I remember working on that code but I
> later decided the base-address aliasing was better done elsewhere).
It looks like it was just lifed from sched.c unchanged.
I
> suspect that the block controlled by the condition you changed in the
> second part of your patch is no longer needed with the new base
> address alias code.
>
> The change is at least half correct: the argument pointer itself can
> never alias a global symbol. One thing to check is whether in any of
> the targets the argument pointer can be variable. If so your change
> might not be safe. The scheduler would not realize that the two
> memory references in
>
> [arg pointer + 4] = x
> arg pointer += 4
> [arg pointer] = y
>
> are to the same address.
Well, where do we want to go? I'm going to lean on you for most alias
problems :-)
Jeff
next prev parent reply other threads:[~1997-10-07 23:14 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
1997-10-06 0:17 Richard Henderson
1997-10-06 6:44 ` John Carr
1997-10-07 23:14 ` Jeffrey A Law [this message]
1997-10-07 23:14 ` Richard Henderson
1997-10-08 4:25 meissner
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