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From: "Sebastian Pop" <sebpop@gmail.com>
To: gcc-bugzilla@gcc.gnu.org
Cc: gcc-bugs@gcc.gnu.org
Subject: Re: [Bug tree-optimization/37573] [4.4 Regression] gcc-4.4 regression: incorrect code generation with -O1 -ftree-vectorize
Date: Wed, 22 Oct 2008 16:10:00 -0000	[thread overview]
Message-ID: <cb9d34b20810220909o6755605eg245eb715c24da9a8@mail.gmail.com> (raw)
In-Reply-To: <20081016081451.31371.qmail@sourceware.org>

> common base.  Consider &s.c[1] and &s + i, obviously the accesses can
> overlap - would you still say so if the base address of the first one
> would be &s.c[0]?

Yes, in the case &s.c[1] versus &s.c[0], we still have to consider the
arrays to potentially overlap.

> (really the base address of a non-variable access is the access
> itself, right?  &s.c[1] in this case)

No, it cannot be &s.c[1] here.  The base object for arrays in structs
should be the struct itself.

The base address tells you what memory object is accessed with an
offset.  For structs, you are allowed to access any of their contents
using arithmetic.  For instance in:

struct s {
  int a[2];
  int c[20];
}

you could access s.c[10] from the address of struct s with: &s.a + 12.


  reply	other threads:[~2008-10-22 16:10 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-09-18 17:31 [Bug tree-optimization/37573] New: " edwintorok at gmail dot com
2008-09-18 17:31 ` [Bug tree-optimization/37573] " edwintorok at gmail dot com
2008-09-18 17:33 ` edwintorok at gmail dot com
2008-09-18 19:15 ` [Bug tree-optimization/37573] [4.4 Regression] " pinskia at gcc dot gnu dot org
2008-09-19 17:03 ` jakub at gcc dot gnu dot org
2008-09-19 17:53 ` jakub at gcc dot gnu dot org
2008-09-21  7:56 ` irar at il dot ibm dot com
2008-10-15 21:30 ` spop at gcc dot gnu dot org
2008-10-15 21:46 ` rguenth at gcc dot gnu dot org
2008-10-15 21:49 ` rguenth at gcc dot gnu dot org
2008-10-16  0:03 ` spop at gcc dot gnu dot org
2008-10-16  8:16 ` rguenther at suse dot de
2008-10-22 16:10   ` Sebastian Pop [this message]
2008-10-22  3:29 ` mmitchel at gcc dot gnu dot org
2008-10-22 16:11 ` sebpop at gmail dot com
2008-10-29 18:49 ` edwintorok at gmail dot com
2008-11-03  9:56 ` rguenth at gcc dot gnu dot org
2008-11-03 12:34 ` rguenth at gcc dot gnu dot org
2008-11-03 12:35 ` rguenth at gcc dot gnu dot org
2008-11-03 17:52 ` edwintorok at gmail dot com

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