From: Joe Buck <jbuck@synopsys.COM>
To: mark@codesourcery.com (Mark Mitchell)
Cc: jbuck@synopsys.com, gcc@gcc.gnu.org, rms@gnu.org
Subject: Re: type based aliasing again
Date: Wed, 08 Sep 1999 19:44:00 -0000 [thread overview]
Message-ID: <199909090242.TAA23209@atrus.synopsys.com> (raw)
In-Reply-To: <19990908184709F.mitchell@codesourcery.com>
Sorry, I responded to Mark's message too quickly and didn't grasp
a key point.
> However, I do think this might be a good way to get useful warnings.
> So, I would amend your proposal to "issue a warning and then tell the
> compiler that there is no aliasing."
Sigh. If we can tell the user's intent, we should try to do the right thing.
If we're going to deliberately do the wrong thing, it would be best
to just issue a hard error. The compiler shouldn't go on to do something
that we know has a good chance of generating bogus code.
So we have three variants.
A). If we detect a rule violation, issue a warning and tell the compiler
to assume aliasing.
B). If we detect a rule violation, issue a warning and tell the compiler
to assume no aliasing. (That is, produce bad code).
C). If we detect a rule violation, issue an error and don't go on.
I think that only A) and C) are reasonable. B) is not. I would prefer
A).
WARNING: multiple messages have this Message-ID
From: Joe Buck <jbuck@synopsys.COM>
To: mark@codesourcery.com (Mark Mitchell)
Cc: jbuck@synopsys.com, gcc@gcc.gnu.org, rms@gnu.org
Subject: Re: type based aliasing again
Date: Thu, 30 Sep 1999 18:02:00 -0000 [thread overview]
Message-ID: <199909090242.TAA23209@atrus.synopsys.com> (raw)
Message-ID: <19990930180200.vdv_LSOZPwRftly3XZz1-j2zhjyzR9Dq2WVRYOigY00@z> (raw)
In-Reply-To: <19990908184709F.mitchell@codesourcery.com>
Sorry, I responded to Mark's message too quickly and didn't grasp
a key point.
> However, I do think this might be a good way to get useful warnings.
> So, I would amend your proposal to "issue a warning and then tell the
> compiler that there is no aliasing."
Sigh. If we can tell the user's intent, we should try to do the right thing.
If we're going to deliberately do the wrong thing, it would be best
to just issue a hard error. The compiler shouldn't go on to do something
that we know has a good chance of generating bogus code.
So we have three variants.
A). If we detect a rule violation, issue a warning and tell the compiler
to assume aliasing.
B). If we detect a rule violation, issue a warning and tell the compiler
to assume no aliasing. (That is, produce bad code).
C). If we detect a rule violation, issue an error and don't go on.
I think that only A) and C) are reasonable. B) is not. I would prefer
A).
next prev parent reply other threads:[~1999-09-08 19:44 UTC|newest]
Thread overview: 408+ messages / expand[flat|nested] mbox.gz Atom feed top
1999-09-08 19:13 Mike Stump
1999-09-08 19:31 ` Joe Buck
1999-09-30 18:02 ` Joe Buck
1999-09-09 7:12 ` Marc Espie
1999-09-09 20:35 ` Jeffrey A Law
1999-09-10 12:29 ` Sudish Joseph
1999-09-30 18:02 ` Sudish Joseph
1999-09-30 18:02 ` Jeffrey A Law
1999-09-30 18:02 ` Marc Espie
1999-09-09 23:25 ` Richard Stallman
1999-09-08 18:11 ` Joe Buck
1999-09-08 18:43 ` Mark Mitchell
1999-09-08 19:25 ` Joe Buck
1999-09-08 19:51 ` David Edelsohn
1999-09-30 18:02 ` David Edelsohn
1999-09-30 18:02 ` Joe Buck
1999-09-08 19:44 ` Joe Buck [this message]
1999-09-08 20:26 ` Mark Mitchell
1999-09-08 20:43 ` Joe Buck
1999-09-08 21:45 ` Mark Mitchell
1999-09-08 22:04 ` Joe Buck
1999-09-08 22:25 ` Mark Mitchell
1999-09-30 18:02 ` Mark Mitchell
1999-09-09 2:08 ` Jeffrey A Law
1999-09-09 10:51 ` Joe Buck
1999-09-09 16:51 ` John Vickers
1999-09-09 17:04 ` Joe Buck
1999-09-09 17:12 ` John Vickers
1999-09-30 18:02 ` John Vickers
1999-09-30 18:02 ` Joe Buck
1999-09-30 18:02 ` John Vickers
1999-09-15 2:07 ` Jeffrey A Law
1999-09-30 18:02 ` Jeffrey A Law
1999-09-30 18:02 ` Joe Buck
1999-09-09 23:26 ` Richard Stallman
1999-09-09 23:38 ` Jeffrey A Law
1999-09-30 18:02 ` Jeffrey A Law
1999-09-30 18:02 ` Richard Stallman
1999-09-09 23:26 ` Richard Stallman
1999-09-30 18:02 ` Richard Stallman
1999-09-30 18:02 ` Jeffrey A Law
1999-09-09 23:25 ` Richard Stallman
1999-09-10 0:06 ` Mark Mitchell
1999-09-10 0:13 ` Joe Buck
1999-09-30 18:02 ` Joe Buck
1999-09-11 0:17 ` Richard Stallman
1999-09-30 18:02 ` Richard Stallman
1999-09-30 18:02 ` Mark Mitchell
1999-09-30 18:02 ` Richard Stallman
1999-09-30 18:02 ` Joe Buck
1999-09-08 23:20 ` Richard Henderson
1999-09-08 23:41 ` Mark Mitchell
1999-09-08 23:44 ` Richard Henderson
1999-09-08 23:51 ` Mark Mitchell
1999-09-30 18:02 ` Mark Mitchell
1999-09-09 2:45 ` Jeffrey A Law
1999-09-30 18:02 ` Jeffrey A Law
1999-09-30 18:02 ` Richard Henderson
1999-09-30 18:02 ` Mark Mitchell
1999-09-30 18:02 ` Richard Henderson
1999-09-30 18:02 ` Mark Mitchell
1999-09-30 18:02 ` Joe Buck
1999-09-08 21:33 ` Joe Buck
1999-09-08 21:56 ` Mark Mitchell
1999-09-30 18:02 ` Mark Mitchell
1999-09-09 1:38 ` Martin v. Loewis
1999-09-30 18:02 ` Martin v. Loewis
1999-09-09 23:25 ` Richard Stallman
1999-09-30 18:02 ` Richard Stallman
1999-09-30 18:02 ` Joe Buck
1999-09-09 2:20 ` Jeffrey A Law
1999-09-09 7:58 ` craig
1999-09-09 10:36 ` Joe Buck
1999-09-09 10:55 ` Mark Mitchell
1999-09-11 0:15 ` Richard Stallman
1999-09-30 18:02 ` Richard Stallman
1999-09-30 18:02 ` Mark Mitchell
1999-09-09 11:51 ` craig
1999-09-09 12:45 ` Joe Buck
1999-09-30 18:02 ` Joe Buck
1999-09-30 18:02 ` craig
1999-09-30 18:02 ` Joe Buck
1999-09-30 18:02 ` craig
1999-09-30 18:02 ` Jeffrey A Law
1999-09-09 23:26 ` Richard Stallman
1999-09-30 18:02 ` Richard Stallman
1999-09-30 18:02 ` Mark Mitchell
1999-09-30 18:02 ` Joe Buck
1999-09-09 23:25 ` Richard Stallman
1999-09-10 0:03 ` Mark Mitchell
1999-09-10 0:23 ` Joe Buck
1999-09-11 0:17 ` Richard Stallman
1999-09-30 18:02 ` Richard Stallman
1999-09-30 18:02 ` Joe Buck
1999-09-11 0:17 ` Richard Stallman
1999-09-30 18:02 ` Richard Stallman
1999-09-30 18:02 ` Mark Mitchell
1999-09-10 14:29 ` Marc Lehmann
1999-09-30 18:02 ` Marc Lehmann
1999-09-15 2:05 ` Jeffrey A Law
1999-09-15 7:55 ` Nick Ing-Simmons
1999-09-30 18:02 ` Nick Ing-Simmons
1999-09-15 23:14 ` Richard Stallman
1999-09-30 18:02 ` Richard Stallman
1999-09-30 18:02 ` Jeffrey A Law
1999-09-30 18:02 ` Richard Stallman
1999-09-30 18:02 ` Mark Mitchell
1999-09-08 20:44 ` Joe Buck
1999-09-30 18:02 ` Joe Buck
1999-09-14 3:04 ` Alexandre Oliva
1999-09-14 5:34 ` Bernd Schmidt
1999-09-14 5:45 ` Alexandre Oliva
1999-09-14 5:52 ` Bernd Schmidt
1999-09-30 18:02 ` Bernd Schmidt
1999-09-21 1:16 ` Rask Ingemann Lambertsen
1999-09-21 2:02 ` Jamie Lokier
1999-09-30 18:02 ` Jamie Lokier
1999-09-30 18:02 ` Rask Ingemann Lambertsen
1999-09-30 18:02 ` Alexandre Oliva
1999-09-14 9:31 ` Andi Kleen
1999-09-30 18:02 ` Andi Kleen
1999-09-30 18:02 ` Bernd Schmidt
1999-09-14 22:22 ` Richard Stallman
1999-09-30 18:02 ` Richard Stallman
1999-09-30 18:02 ` Alexandre Oliva
1999-09-30 18:02 ` Joe Buck
1999-09-10 0:11 ` Joe Buck
1999-09-10 8:43 ` craig
1999-09-10 18:25 ` Jonathan Larmour
1999-09-11 3:50 ` craig
1999-09-30 18:02 ` craig
1999-09-30 18:02 ` Jonathan Larmour
1999-09-11 0:15 ` Richard Stallman
1999-09-11 3:51 ` craig
1999-09-12 0:51 ` Richard Stallman
1999-09-12 8:54 ` craig
1999-09-13 0:47 ` Richard Stallman
1999-09-30 18:02 ` Richard Stallman
1999-09-30 18:02 ` craig
1999-09-30 18:02 ` Richard Stallman
1999-09-30 18:02 ` craig
1999-09-30 18:02 ` Richard Stallman
1999-09-30 18:02 ` craig
1999-09-11 0:14 ` Richard Stallman
1999-09-11 15:20 ` Mark Mitchell
1999-09-11 18:04 ` David Edelsohn
1999-09-11 18:20 ` Mark Mitchell
1999-09-11 23:40 ` Sudish Joseph
1999-09-30 18:02 ` Sudish Joseph
1999-09-12 8:16 ` Robert Lipe
1999-09-30 18:02 ` Robert Lipe
1999-09-30 18:02 ` Mark Mitchell
1999-09-13 0:47 ` Richard Stallman
1999-09-15 2:06 ` Jeffrey A Law
1999-09-15 8:02 ` Nick Ing-Simmons
1999-09-15 9:20 ` Jeffrey A Law
1999-09-15 9:31 ` David Edelsohn
1999-09-15 10:02 ` craig
1999-09-16 23:13 ` Richard Stallman
1999-09-17 1:51 ` craig
1999-09-17 22:16 ` Richard Stallman
1999-09-30 18:02 ` Richard Stallman
1999-09-30 18:02 ` craig
1999-09-30 18:02 ` Richard Stallman
1999-09-30 18:02 ` craig
1999-09-30 18:02 ` David Edelsohn
1999-09-15 9:56 ` Nick Ing-Simmons
1999-09-15 10:08 ` craig
1999-09-15 10:48 ` Nick Ing-Simmons
1999-09-15 14:32 ` craig
1999-09-30 18:02 ` craig
1999-09-30 18:02 ` Nick Ing-Simmons
1999-09-16 10:54 ` Andi Kleen
1999-09-16 12:08 ` Joern Rennecke
1999-09-16 12:18 ` Mark Mitchell
1999-09-17 7:07 ` __typealias qualifier (was Re: type based aliasing again) patl
1999-09-17 8:32 ` Mark Mitchell
1999-09-30 18:02 ` Mark Mitchell
1999-09-30 18:02 ` Patrick J. LoPresti
1999-09-30 18:02 ` type based aliasing again Mark Mitchell
1999-09-30 18:02 ` Joern Rennecke
1999-09-16 14:29 ` craig
1999-09-16 22:19 ` Andi Kleen
1999-09-30 18:02 ` Andi Kleen
1999-09-30 18:02 ` craig
1999-09-30 18:02 ` Andi Kleen
1999-09-16 23:13 ` Richard Stallman
1999-09-30 18:02 ` Richard Stallman
1999-09-30 18:02 ` craig
1999-09-30 18:02 ` Nick Ing-Simmons
1999-09-30 18:02 ` Jeffrey A Law
1999-09-30 18:02 ` Nick Ing-Simmons
1999-09-15 23:14 ` Richard Stallman
1999-09-30 18:02 ` Richard Stallman
1999-09-30 18:02 ` Jeffrey A Law
1999-09-30 18:02 ` Richard Stallman
1999-09-30 18:02 ` David Edelsohn
1999-09-12 9:45 ` Jonathan Larmour
1999-09-30 18:02 ` Jonathan Larmour
1999-09-13 0:47 ` Richard Stallman
1999-09-30 18:02 ` Richard Stallman
1999-09-13 4:05 ` Richard Earnshaw
1999-09-15 2:05 ` Jeffrey A Law
1999-09-30 18:02 ` Jeffrey A Law
1999-09-30 18:02 ` Richard Earnshaw
1999-09-30 18:02 ` Mark Mitchell
1999-09-30 18:02 ` Richard Stallman
1999-09-30 18:02 ` Joe Buck
1999-09-30 18:02 ` Richard Stallman
1999-09-30 18:02 ` Mike Stump
1999-09-09 14:26 Mike Stump
1999-09-09 14:38 ` Mark Mitchell
1999-09-11 0:16 ` Richard Stallman
1999-09-15 2:07 ` Jeffrey A Law
1999-09-30 18:02 ` Jeffrey A Law
1999-09-30 18:02 ` Richard Stallman
1999-09-30 18:02 ` Mark Mitchell
1999-09-30 18:02 ` Mike Stump
1999-09-09 15:40 Claus Fischer
1999-09-09 15:57 ` David Starner
1999-09-09 16:24 ` Claus Fischer
1999-09-09 16:55 ` Joe Buck
1999-09-09 17:31 ` Claus Fischer
1999-09-30 18:02 ` Claus Fischer
1999-09-30 18:02 ` Joe Buck
1999-09-10 8:42 ` craig
1999-09-30 18:02 ` craig
1999-09-30 18:02 ` Claus Fischer
1999-09-30 18:02 ` David Starner
1999-09-09 16:37 ` Jeffrey A Law
1999-09-09 17:15 ` Claus Fischer
1999-09-30 18:02 ` Claus Fischer
1999-09-30 18:02 ` Jeffrey A Law
1999-09-30 18:02 ` Claus Fischer
1999-09-09 21:54 Alex Rosenberg
1999-09-30 18:02 ` Alex Rosenberg
1999-09-10 8:43 craig
1999-09-12 0:49 ` Richard Stallman
1999-09-30 18:02 ` Richard Stallman
1999-09-30 18:02 ` craig
1999-09-11 18:21 Phil Edwards
1999-09-30 18:02 ` Phil Edwards
1999-09-11 21:48 N8TM
1999-09-30 18:02 ` N8TM
[not found] <9377.936981585@upchuck.cygnus.com>
1999-09-12 0:52 ` Richard Stallman
1999-09-30 18:02 ` Richard Stallman
1999-09-12 11:20 Josh Stern
1999-09-30 18:02 ` Josh Stern
1999-09-13 10:55 R. Kelley Cook
1999-09-13 13:22 ` craig
1999-09-30 18:02 ` craig
1999-09-30 18:02 ` R. Kelley Cook
1999-09-13 16:34 Mike Stump
1999-09-14 22:20 ` Richard Stallman
1999-09-30 18:02 ` Richard Stallman
1999-09-30 18:02 ` Mike Stump
1999-09-13 21:45 N8TM
1999-09-14 4:01 ` Marc Espie
1999-09-14 9:56 ` David Edelsohn
1999-09-14 10:10 ` Richard Earnshaw
1999-09-14 10:31 ` Nick Ing-Simmons
1999-09-14 10:52 ` David Edelsohn
1999-09-14 11:11 ` craig
1999-09-14 14:44 ` David Edelsohn
1999-09-30 18:02 ` David Edelsohn
1999-09-14 15:06 ` David Edelsohn
1999-09-14 17:35 ` Marc Lehmann
1999-09-30 18:02 ` Marc Lehmann
1999-09-14 23:41 ` craig
1999-09-15 8:28 ` Marc Lehmann
1999-09-30 18:02 ` Marc Lehmann
1999-09-15 9:19 ` David Edelsohn
1999-09-15 9:59 ` Nick Ing-Simmons
1999-09-15 15:33 ` David Edelsohn
1999-09-30 18:02 ` David Edelsohn
1999-09-30 18:02 ` Nick Ing-Simmons
1999-09-15 10:01 ` craig
1999-09-30 18:02 ` craig
1999-09-30 18:02 ` David Edelsohn
1999-09-30 18:02 ` craig
1999-09-30 18:02 ` David Edelsohn
1999-09-30 18:02 ` craig
1999-09-14 11:58 ` Gerald Pfeifer
1999-09-30 18:02 ` Gerald Pfeifer
1999-09-30 18:02 ` David Edelsohn
1999-09-14 11:01 ` craig
1999-09-14 11:14 ` craig
1999-09-30 18:02 ` craig
1999-09-14 11:39 ` Mark Mitchell
1999-09-14 14:48 ` Toon Moene
1999-09-14 15:00 ` David Edelsohn
1999-09-14 16:01 ` Toon Moene
1999-09-14 16:15 ` David Edelsohn
1999-09-14 16:43 ` Mark Mitchell
1999-09-30 18:02 ` Mark Mitchell
1999-09-14 17:39 ` Marc Lehmann
1999-09-30 18:02 ` Marc Lehmann
1999-09-30 18:02 ` David Edelsohn
1999-09-14 16:19 ` dvv
1999-09-14 17:38 ` Michael Meissner
1999-09-30 18:02 ` Michael Meissner
1999-09-30 18:02 ` Dima Volodin
1999-09-30 18:02 ` Toon Moene
1999-09-30 18:02 ` David Edelsohn
1999-09-14 15:08 ` Mark Mitchell
1999-09-30 18:02 ` Mark Mitchell
1999-09-30 18:02 ` Toon Moene
1999-09-30 18:02 ` Mark Mitchell
1999-09-30 18:02 ` craig
1999-09-14 23:46 ` Geoff Keating
1999-09-15 7:47 ` Nick Ing-Simmons
1999-09-30 18:02 ` Nick Ing-Simmons
1999-09-30 18:02 ` Geoff Keating
1999-09-30 18:02 ` Nick Ing-Simmons
1999-09-30 18:02 ` Richard Earnshaw
1999-09-14 17:22 ` Marc Lehmann
1999-09-30 18:02 ` Marc Lehmann
1999-09-30 18:02 ` David Edelsohn
1999-09-14 17:23 ` Marc Lehmann
1999-09-15 1:59 ` Marc Espie
1999-09-15 8:28 ` Marc Lehmann
1999-09-30 18:02 ` Marc Lehmann
1999-09-30 18:02 ` Marc Espie
1999-09-30 18:02 ` Marc Lehmann
1999-09-15 2:01 ` Jeffrey A Law
1999-09-30 18:02 ` Jeffrey A Law
1999-09-30 18:02 ` Marc Espie
1999-09-30 18:02 ` N8TM
1999-09-14 6:46 Marcel Cox
1999-09-14 6:50 ` Bernd Schmidt
1999-09-14 7:14 ` Marcel Cox
1999-09-14 8:45 ` Jamie Lokier
1999-09-30 18:02 ` Jamie Lokier
1999-09-30 18:02 ` Marcel Cox
1999-09-30 18:02 ` Bernd Schmidt
1999-09-30 18:02 ` Marcel Cox
1999-09-15 7:02 David Ronis
1999-09-30 18:02 ` David Ronis
1999-09-15 8:27 Kaveh R. Ghazi
1999-09-15 8:57 ` Nathan Sidwell
1999-09-30 18:02 ` Nathan Sidwell
1999-09-30 18:02 ` Kaveh R. Ghazi
1999-09-15 11:42 Michael J. Bedy
1999-09-15 14:32 ` craig
1999-09-16 23:14 ` Richard Stallman
1999-09-30 18:02 ` Richard Stallman
1999-09-30 18:02 ` craig
1999-09-30 18:02 ` Michael J. Bedy
1999-09-15 21:47 Florin Mateoc
1999-09-16 2:18 ` craig
1999-09-30 18:02 ` craig
1999-09-30 18:02 ` Florin Mateoc
[not found] <Pine.SO4.4.05.9909160153420.23533-100000@tamarack.cs.mtu.edu>
1999-09-16 2:19 ` craig
1999-09-30 18:02 ` craig
1999-09-16 6:12 Artem Hodyush
1999-09-16 23:15 ` Richard Stallman
1999-09-16 23:38 ` Gabriel Dos_Reis
1999-09-17 22:16 ` Richard Stallman
1999-09-30 18:02 ` Richard Stallman
1999-09-30 18:02 ` Gabriel Dos_Reis
1999-09-30 18:02 ` Richard Stallman
1999-09-30 18:02 ` Artem Hodyush
[not found] <199909161750.LAA12073@basho.fc.hp.com>
1999-09-16 14:29 ` craig
1999-09-20 15:17 ` John W. Stevens
1999-09-30 18:02 ` John W. Stevens
1999-09-30 18:02 ` craig
1999-09-17 9:02 Harvey J. Stein
1999-09-30 18:02 ` Harvey J. Stein
1999-09-18 2:51 Ross Morgan-Linial
[not found] ` <19990918151905.F1650@cerebro.laendle>
1999-09-18 22:18 ` Ross Morgan-Linial
1999-09-30 18:02 ` Ross Morgan-Linial
1999-09-30 18:02 ` Ross Morgan-Linial
1999-09-18 3:25 Artem Hodyush
1999-09-18 11:29 ` Russ Allbery
1999-09-20 5:54 ` Joern Rennecke
1999-09-30 18:02 ` Joern Rennecke
1999-09-30 18:02 ` Russ Allbery
1999-09-19 13:54 ` Richard Stallman
1999-09-30 18:02 ` Richard Stallman
1999-09-21 8:50 ` Harvey J. Stein
1999-09-30 18:02 ` Harvey J. Stein
1999-09-30 18:02 ` Artem Hodyush
1999-09-18 7:30 Stephen L Moshier
1999-09-30 18:02 ` Stephen L Moshier
1999-09-18 8:33 N8TM
1999-09-30 18:02 ` N8TM
1999-09-21 8:48 Harvey J. Stein
1999-09-22 12:15 ` Richard Stallman
1999-09-22 13:08 ` Harvey J. Stein
1999-09-24 23:37 ` Richard Stallman
1999-09-30 18:02 ` Richard Stallman
1999-09-30 18:02 ` Harvey J. Stein
1999-09-30 18:02 ` Richard Stallman
1999-09-30 18:02 ` Harvey J. Stein
[not found] <19990921182843.25292.qmail@deer>
1999-09-21 15:47 ` John W. Stevens
1999-09-21 16:15 ` craig
1999-09-21 20:37 ` David Edelsohn
1999-09-30 18:02 ` David Edelsohn
1999-09-23 9:06 ` John W. Stevens
1999-09-23 11:06 ` craig
1999-09-30 18:02 ` craig
1999-09-30 18:02 ` John W. Stevens
1999-09-30 18:02 ` craig
1999-09-27 6:56 ` Rask Ingemann Lambertsen
1999-09-27 8:32 ` Joe Buck
1999-09-30 18:02 ` Joe Buck
1999-09-30 18:02 ` Rask Ingemann Lambertsen
1999-09-30 18:02 ` John W. Stevens
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