From: Jeffrey A Law <law@hurl.cygnus.com>
To: Bernd Schmidt <crux@Pool.Informatik.RWTH-Aachen.DE>
Cc: egcs@cygnus.com
Subject: Re: Some Haifa scheduler bugs
Date: Wed, 03 Sep 1997 09:37:00 -0000 [thread overview]
Message-ID: <15524.873304637@hurl.cygnus.com> (raw)
In-Reply-To: <Pine.SOL.3.90.970903182436.5858D-100000@bond.informatik.rwth-aachen.de>
In message < Pine.SOL.3.90.970903182436.5858D-100000@bond.informatik.rwth-aachen.de >you write:
> Ok, I'll retry the tests without that option. But this is not the only
> case that Haifa can create incorrect code; there is an additional problem
> that can show up on any SMALL_REGISTER_CLASSES machine. Haifa can increase
> the lifetime of pseudo registers, which can cause incorrect code to be
> generated. These examples were made on an i586-linux configuration with
> egcs-970828:
[ ... ]
In general, that's not going to work.
Basically any machine that defines SMALL_REGISTER_CLASSES and passes args in
registers is playing with fire -- reload can and will silently generate incorrect
code for such targets. For that reason I _highly_ recommend against using
registers for parameter passing on the x86 targets.
Turning on the instruction scheduler in that case is just going to make a
bad problem worse -- but the problem isn't the instruction scheduler itself.
> It seems that at least these changes are necessary:
> 1. Function arguments must be moved into pseudos immediately at the top
> of a function.
Nontrivial to do in haifa.
jeff
next prev parent reply other threads:[~1997-09-03 9:37 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <Pine.SOL.3.90.970826140826.2901J-100000@maigret.informatik.rwth-aachen.de>
1997-09-01 20:33 ` Jeffrey A Law
1997-09-03 9:30 ` Bernd Schmidt
1997-09-03 9:37 ` Jeffrey A Law [this message]
1997-09-03 9:44 ` Bernd Schmidt
1997-09-03 10:07 ` Jeffrey A Law
1997-09-05 7:15 ` Bernd Schmidt
1997-09-05 7:55 ` Jeffrey A Law
1997-09-05 8:33 ` Ian Lance Taylor
1997-09-03 11:58 ` Jim Wilson
1997-09-04 1:16 ` regparm & other gcc bug Martynas Kunigelis
1997-09-05 9:29 ` Kamil Iskra
1997-09-06 5:19 ` Martynas Kunigelis
1997-09-03 11:39 ` Some Haifa scheduler bugs Paul Koning
1997-09-03 11:50 ` David Edelsohn
1997-09-03 13:13 ` Richard Henderson
1997-09-03 13:19 ` Jeffrey A Law
1997-09-04 9:33 ` Craig Burley
1997-09-04 11:12 ` Jeffrey A Law
1997-09-04 11:33 ` David S. Miller
1997-09-04 14:38 ` David Edelsohn
1997-09-04 11:27 meissner
[not found] <Pine.SOL.3.90.970826141030.2901K-100000@maigret.informatik.rwth-aachen.de>
1997-09-01 20:42 ` Jeffrey A Law
-- strict thread matches above, loose matches on Subject: below --
1997-08-26 14:34 Bernd Schmidt
1997-08-22 13:53 Building of generated parser files Andreas Schwab
1997-08-22 15:02 ` Some Haifa scheduler bugs Jeffrey A Law
1997-08-22 15:24 ` Jeffrey A Law
1997-08-22 10:48 Building of generated parser files Niklas Hallqvist
1997-08-22 13:28 ` Some Haifa scheduler bugs Bernd Schmidt
1997-08-21 16:51 Problems on PowerPC David Edelsohn
1997-08-21 17:43 ` Some Haifa scheduler bugs Jeffrey A Law
1997-08-21 15:20 egcs repository Joel Sherrill
1997-08-21 15:47 ` Some Haifa scheduler bugs Bernd Schmidt
1997-08-19 19:00 Jeffrey A Law
1997-08-19 17:54 Jeffrey A Law
1997-08-19 7:36 egcs: A new compiler project to merge the existing GCC forks (fwd) Robert Wilhelm
1997-08-19 9:34 ` Some Haifa scheduler bugs Bernd Schmidt
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