From: Jeffrey A Law <law@cygnus.com>
To: Toon Moene <toon@moene.indiv.nluug.nl>
Cc: "David S. Miller" <davem@dm.cobaltmicro.com>, egcs@cygnus.com
Subject: Re: egcs-1.1 release schedule
Date: Mon, 22 Jun 1998 22:29:00 -0000 [thread overview]
Message-ID: <17825.898579545@hurl.cygnus.com> (raw)
In-Reply-To: <9806222039.AA04066@moene.indiv.nluug.nl>
In message < 9806222039.AA04066@moene.indiv.nluug.nl >you write:
> PS: I agree with Jeff (even I don't know all the details
Quick lesson then :-) Ignore if you're not really interested in
the guts of why increasing STACK_BOUNDARY is a bad idea.
GCC assumes that the stack pointer must always be a multiple of
STACK_BOUNDARY. And it even has optimizations which use that info.
combine will actually notice cases where the masking off of low bits
should be unnecessary due to the value of STACK_BOUNDARY. ie if
STACK_BOUNDARY is 64, then ((sp + x) & 0xfffffffc)) can be resolved
to just (sp + x) (assuming X is a multiple of STACK_BOUNDARY).
This optimization will generate code which does not work if somehow
we get into a function where the stack is improperly aligned. The
canonical example would be a callback from libc like the comparison
routine for qsort.
jeff
next prev parent reply other threads:[~1998-06-22 22:29 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
1998-06-18 1:32 Jeffrey A Law
1998-06-19 9:02 ` Gerald Pfeifer
1998-06-19 23:47 ` Jeffrey A Law
1998-06-19 11:57 ` Dave Love
1998-06-21 21:43 ` Craig Burley
1998-06-21 23:07 ` Jeffrey A Law
1998-06-22 5:19 ` David S. Miller
1998-06-22 12:04 ` Dave Love
1998-06-22 13:45 ` Toon Moene
1998-06-22 22:29 ` Jeffrey A Law [this message]
1998-06-22 18:20 ` ix86 double alignment (was Re: egcs-1.1 release schedule) Craig Burley
1998-06-23 3:32 ` David S. Miller
1998-06-23 6:30 ` Craig Burley
1998-06-23 3:32 ` Jeffrey A Law
1998-06-23 5:13 ` Craig Burley
1998-06-22 12:04 ` egcs-1.1 release schedule Dave Love
1998-06-23 3:32 ` Craig Burley
1998-06-23 3:32 ` Jeffrey A Law
1998-06-23 9:29 ` H.J. Lu
1998-06-24 17:12 ` x86 double alignment (was egcs-1.1 release schedule) Marc Lehmann
1998-06-25 0:25 ` Jeffrey A Law
1998-06-28 18:02 ` Marc Lehmann
1998-06-25 12:33 ` PÃ¥l-Kristian Engstad
1998-06-28 18:02 ` Marc Lehmann
1998-06-25 21:48 ` Craig Burley
1998-06-25 18:53 ` Jeffrey A Law
1998-06-28 22:41 ` Marc Lehmann
1998-06-29 5:20 ` Martin Kahlert
1998-06-29 11:08 ` Jeffrey A Law
1998-06-29 19:43 ` Craig Burley
1998-06-29 20:41 ` Craig Burley
1998-06-30 0:42 ` Jeffrey A Law
1998-06-30 8:19 ` gcc2 merge H.J. Lu
1998-06-30 19:49 ` Jeffrey A Law
1998-06-30 4:50 ` x86 double alignment (was egcs-1.1 release schedule) Jeffrey A Law
1998-06-22 12:04 ` ix86 `double' alignment (was " Craig Burley
1998-06-23 3:32 ` Jeffrey A Law
1998-06-23 5:13 ` Craig Burley
1998-06-24 2:28 ` Jeffrey A Law
1998-06-24 14:50 ` Craig Burley
1998-06-25 0:25 ` Jeffrey A Law
1998-06-25 9:59 ` Tim Hollebeek
1998-06-28 18:01 ` Marc Lehmann
1998-06-20 6:41 ` egcs-1.1 release schedule Gabriel Dos Reis
1998-06-20 9:22 ` Joe Buck
1998-06-20 15:36 ` Mark Mitchell
1998-06-21 0:07 ` Jeffrey A Law
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