From: Richard Henderson <rth@redhat.com>
To: Franz Sirl <Franz.Sirl-kernel@lauterbach.com>
Cc: John David Anglin <dave@hiauly1.hia.nrc.ca>,
gcc@gcc.gnu.org, gianni@scaramanga.co.uk
Subject: Re: Altivec + 16 byte alignment
Date: Wed, 12 Feb 2003 21:46:00 -0000 [thread overview]
Message-ID: <20030212214621.GE29744@redhat.com> (raw)
In-Reply-To: <200302122207.54496@enzo.bigblue.local>
On Wed, Feb 12, 2003 at 10:07:54PM +0100, Franz Sirl wrote:
> ... and the stack pointer is kept aligned (to 256 bits) by
> independent code as well
Is this 256 bits ABI mandated? I.e. will a non-gcc ppc
compiler maintain this alignment as well?
If yes, then STACK_ALIGNMENT is set too low. You should
advertise what you have. If no, then calling between two
functions compiled with different compilers will not
preserve the 256 bit alignment you claim.
There are passes in gcc, particularly combine, that look
at the advertised alignment for a pointer and know that
the low bits are zero, and perform optimizations based on
this. If the alignment doesn't exist, the optimizations
produce incorrect results.
r~
next prev parent reply other threads:[~2003-02-12 21:46 UTC|newest]
Thread overview: 71+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-02-11 17:25 John David Anglin
2003-02-11 18:29 ` Franz Sirl
2003-02-11 18:32 ` David Edelsohn
2003-02-11 18:57 ` Franz Sirl
2003-02-11 22:35 ` Spundun Bhatt
[not found] ` <1045070773.1118.140.camel@lemsip>
2003-02-12 18:06 ` Spundun Bhatt
2003-02-12 0:42 ` Richard Henderson
2003-02-12 21:17 ` Franz Sirl
2003-02-12 21:46 ` Richard Henderson [this message]
2003-02-12 22:31 ` Franz Sirl
2003-02-13 0:04 ` Gabriel Paubert
2003-02-12 22:47 ` John David Anglin
2003-02-13 0:40 ` Richard Henderson
2003-02-13 6:31 ` John David Anglin
2003-02-13 8:59 ` Richard Henderson
2003-02-13 18:06 ` John David Anglin
2003-02-17 20:00 ` [PATCH]: Stack alignment John David Anglin
2003-02-17 20:47 ` Geoff Keating
2003-02-17 22:27 ` John David Anglin
2003-02-18 0:04 ` John David Anglin
2003-03-01 19:32 ` [PATCH]: Stack alignment - take 2 John David Anglin
2003-03-04 3:34 ` Richard Henderson
-- strict thread matches above, loose matches on Subject: below --
2003-02-12 14:15 Altivec + 16 byte alignment Richard Kenner
2003-02-11 22:28 Richard Kenner
2003-02-11 22:27 Robert Dewar
2003-02-11 22:18 Richard Kenner
2003-02-11 22:25 ` Neil Booth
2003-02-11 22:10 Richard Kenner
2003-02-11 22:15 ` Neil Booth
2003-02-11 22:05 Richard Kenner
2003-02-11 22:09 ` Neil Booth
2003-02-11 21:10 Richard Kenner
2003-02-11 20:36 Richard Kenner
2003-02-11 20:39 ` Neil Booth
2003-02-11 20:46 ` tm_gccmail
2003-02-11 20:33 Richard Kenner
2003-02-11 20:34 ` Neil Booth
[not found] <no.id>
2003-02-11 19:59 ` John David Anglin
2003-02-11 21:02 ` Mike Stump
2003-02-12 5:55 ` Fergus Henderson
2003-02-12 16:39 ` John David Anglin
2003-02-11 19:44 Richard Kenner
2003-02-11 19:43 Richard Kenner
2003-02-11 20:02 ` Geoff Keating
2003-02-12 0:52 ` Richard Henderson
2003-02-11 19:18 Richard Kenner
2003-02-11 19:03 Richard Kenner
2003-02-11 19:11 ` Mike Stump
2003-02-11 19:26 ` Geoff Keating
2003-02-11 19:40 ` David Edelsohn
2003-02-11 20:29 ` Neil Booth
2003-02-11 20:45 ` Geoff Keating
2003-02-11 22:03 ` Neil Booth
2003-02-11 22:07 ` Neil Booth
2003-02-11 20:01 ` Geert Bosch
2003-02-11 18:34 Richard Kenner
2003-02-11 18:59 ` Geoff Keating
2003-02-11 10:07 Gianni Tedesco
2003-02-11 14:18 ` Gianni Mariani
2003-02-11 14:49 ` Gianni Mariani
2003-02-11 14:57 ` Gianni Tedesco
2003-02-11 19:26 ` tm_gccmail
2003-02-11 14:32 ` Michael S. Zick
2003-02-11 14:49 ` Gianni Tedesco
2003-02-11 23:58 ` Daniel Egger
2003-02-14 2:41 ` Segher Boessenkool
2003-02-14 16:07 ` Michael S. Zick
[not found] <Message from Franz Sirl <Franz.Sirl-kernel@lauterbach.com>
2002-02-21 6:26 ` powerpc-linux-gnu bootstrap fail Franz Sirl
2002-02-21 8:37 ` David Edelsohn
2002-02-21 10:07 ` Franz Sirl
2002-02-22 8:59 ` Daniel Egger
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