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Re: Urgent: bug fixes needed for GCC 3.0.2
- To: Mark Mitchell <mark at codesourcery dot com>
- Subject: Re: Urgent: bug fixes needed for GCC 3.0.2
- From: law at redhat dot com
- Date: Thu, 04 Oct 2001 10:14:15 -0600
- cc: "gcc at gcc dot gnu dot org" <gcc at gcc dot gnu dot org>, "wilson at redhat dot com" <wilson at redhat dot com>, "jh at suse dot cz" <jh at suse dot cz>
- Reply-To: law at redhat dot com
In message <firstname.lastname@example.org>you write:
> > Well, if it wasn't for the sibcall optimization the stack slot would be
> > unchanging. That's the crux of the issue.
> Yes. Perhaps a good fix, in the 3.0.2 time frame, is to turn off
> RTX_UNCHANGING_P if flag_sibling_calls is on.
> > If we believe that without the sibcall that having RTX_UNCHANGING_P set i
> > correct and desirable, then we need to clear the bit if we have a sibcall
> > since the sibcall sequence will overwrite the incoming stack slots. This
> > may (or may not) be a difficult thing to do.
> It sounds difficult to me. Especially to get right the first time.
Also possibly true. Though I was thinking that these MEMs ought to be
not terribly difficult to find since before virtual register instantiation
since they would all reference the incoming argument pointer. In theory
one pass over the RTL would find them.