From: mrs@wrs.com (Mike Stump)
To: egcs@cygnus.com
Subject: Re: m68k structure packing
Date: Wed, 01 Oct 1997 12:16:00 -0000 [thread overview]
Message-ID: <199710011915.MAA01070@kankakee.wrs.com> (raw)
> Date: Tue, 30 Sep 1997 23:05:48 -0600
> From: Jeffrey A Law <law@hurl.cygnus.com>
> In message <199710010315.UAA28203@kankakee.wrs.com>you write:
> > Don't know how. All I can do it try a couple of testcases that should
> > expose the tricky parts, I have done that.
> Read the docs for PCC_BITFIELD_MATTERS.
Sorry I have given the impression that I haven't read that, that isn't
the case.
> It describes a very particular problem (bitfields crossing certain
> alignment boundaries).
Yes. Again, sorry I gave the impression that I didn't read, understand
and try the case discussed, as that isn't the case.
> It even includes code which attempts to set up this situation;
Yes...
> Then look at the resulting output
I must admit I didn't do that before because I didn't see that it
could offer any additional insight. But, since you think it has some
relevance, I took a look at the output (and a few variations on it)
and I still don't see how it can offer any additional insight. I did
see what I consider some additional minor nits... like padding at the
end when :0 is used, that we may want to go ahead and remove (padding
on a packed structure isn't desired or useful), and undesired
alignment when :0 is used, and because of the presence of the
undesired alignment, aligned loads and stores are generated, since the
data is aligned. This, while it is a bug, won't cause codegen
problems, just incompatibilities if/when we fix that problem.
> and verify that you don't have any unaligned loads/stores.
Sorry I gave the impression that I haven't tested it, as that is not true.
> Doesn't seem all that hard to me.
Nor to me, as I I have already done all the testing that you seem to
imply. Let me put it another way, I am to the point of happiness with
the code, that I don't know of any additional way to test it by hand.
> I think if you do that and can show Jim that it works then you'll
> both be happy.
Ah, now here is something I didn't do. I have not shown you all all
the testcases I have looked at, nor all the resulting code... I'll
see about putting together another mail message with all that you
request, but in general this isn't how I normally operate. I normally
keep that level of detail to myself, and when the code is as I want,
then I submit the patches I've developed enmass.
I don't think we should force authors of code to prove to kenner that
a change is good enough for the FSF's compiler, and then force them to
go through the pain again to get it into the egcs compiler. I think
we risk faster divergence that way, and keeping them converged is
better. I thought that kenner would be generally be harder to deal
with, and while I may still generally think that is true, it wasn't in
this case.
next reply other threads:[~1997-10-01 12:16 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
1997-10-01 12:16 Mike Stump [this message]
1997-10-01 12:39 ` Joel Sherrill
1997-10-02 18:37 ` Jim Wilson
-- strict thread matches above, loose matches on Subject: below --
1997-10-01 15:08 Mike Stump
1997-10-01 15:56 ` Peter Barada
1997-10-01 16:16 ` Per Bothner
1997-10-02 20:14 ` Jim Wilson
1997-10-02 6:49 ` Paul Koning
1997-10-02 20:09 ` Jim Wilson
1997-10-02 20:01 ` Jim Wilson
1997-10-02 21:40 ` Richard Henderson
1997-09-30 21:42 Jim Wilson
1997-10-01 5:44 ` Kamil Iskra
1997-09-30 20:16 Mike Stump
1997-09-30 22:03 ` Jeffrey A Law
1997-09-30 16:58 Mike Stump
1997-09-30 18:20 ` Jim Wilson
1997-10-01 9:02 ` Peter Barada
1997-09-30 13:32 Mike Stump
1997-09-30 14:56 ` Jim Wilson
1997-09-30 12:08 Mike Stump
1997-09-30 12:57 ` Charles M. Hannum
1997-09-30 19:58 ` Jim Wilson
1997-09-30 21:13 ` Richard Henderson
1997-09-30 21:22 ` Jim Wilson
1997-10-01 15:14 ` Jim Wilson
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