From: Richard Henderson <rth@cygnus.com>
To: Jim Wilson <wilson@cygnus.com>
Cc: Richard Henderson <rth@cygnus.com>, egcs@cygnus.com
Subject: Re: alpha failure on 920810-1
Date: Wed, 29 Apr 1998 02:20:00 -0000 [thread overview]
Message-ID: <19980428230405.38649@dot.cygnus.com> (raw)
In-Reply-To: <199804290430.VAA25220@rtl.cygnus.com>
On Tue, Apr 28, 1998 at 09:30:43PM -0700, Jim Wilson wrote:
> I suspect that there are no currently supported machines for which your
> get_condition change is wrong, but there may be future architectures for
> which is it wrong.
Actually, part of the comment was _defining_ FPmode+VOIDmode to act a
that way. That future architecture might use FPmode+FPmode for that.
Sigh. It wasn't such a good idea, I guess.
> Adding a strategic unspec operation could fix the problem, at the expense
> of uglifying the alpha.md file a bit, and perhaps losing some optimizations.
> It is likely a simpler solution though.
Hum. I suppose
(set (reg:DF 1)
(eq:DF (reg:DF 2) (reg:DF 3)))
(set (reg:DF 4)
(if_then_else:DF (eq (unspec [(reg:DF 1)] 9)
(const_double 0))
(reg:DF 5)
(reg:DF 4)))
would work. It would still allow the sense of the comparisons to be
switched while disallowing their combination. It doesn't strike me
as particularly nice, though.
As for combine, I think it needs fixing for other reasons -- Sparc v9
is failing the same test because of the same type of problem, that is,
the entire function being optimized away. But it is doing it in a way
different from what was happening on Alpha -- I havn't examined it in
detail yet.
So you think changing get_condition and possibly combine is the wrong
approach, eh? Well, I guess I'll figure something out...
r~
next prev parent reply other threads:[~1998-04-29 2:20 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
1998-04-27 1:41 Richard Henderson
1998-04-27 8:47 ` Joern Rennecke
1998-04-27 13:59 ` Richard Henderson
1998-04-28 22:14 ` Jim Wilson
1998-04-29 2:20 ` Richard Henderson [this message]
1998-04-29 12:27 ` Jim Wilson
1998-04-29 16:08 ` Joern Rennecke
1998-04-29 22:57 ` Richard Henderson
1998-04-30 10:25 ` Joern Rennecke
1998-04-30 13:20 ` Richard Henderson
1998-04-30 22:29 ` Richard Henderson
1998-05-08 16:08 ` Jeffrey A Law
1998-05-09 2:05 ` Richard Henderson
1998-05-06 23:49 ` Jeffrey A Law
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