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From: "chtz at informatik dot uni-bremen.de" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/53900] [regression] Too optimistic on a alignment assert
Date: Mon, 07 Jan 2013 10:19:00 -0000 [thread overview]
Message-ID: <bug-53900-4-Ghl4cgysZt@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-53900-4@http.gcc.gnu.org/bugzilla/>
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53900
--- Comment #7 from Christoph Hertzberg <chtz at informatik dot uni-bremen.de> 2013-01-07 10:19:13 UTC ---
(In reply to comment #6)
> > __attribute__((aligned(16))) float array[4];
>
> Explicitly says the array is aligned to 16 bytes which means it is undefined by
> the C/C++ standard what happens if you a pointer to the struct which contains
> this array. As this pointer will always be aligned by definition of the struct
> (and any other use of it is undefined), then by definition
> std::ptrdiff_t(array) will always have the lower 8bits be zero.
So does that mean that new and std::allocator act undefined for aligned
objects?
Is there anything wrong with Gael's second test case?
next prev parent reply other threads:[~2013-01-07 10:19 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-09 14:57 [Bug c++/53900] New: " gael.guennebaud at gmail dot com
2012-07-09 15:23 ` [Bug c++/53900] [regression] " rguenth at gcc dot gnu.org
2012-07-09 16:12 ` gael.guennebaud at gmail dot com
2012-07-09 16:19 ` rguenth at gcc dot gnu.org
2012-07-10 11:09 ` gael.guennebaud at gmail dot com
2012-12-28 17:47 ` xarthisius.kk at gmail dot com
2013-01-07 4:27 ` pinskia at gcc dot gnu.org
2013-01-07 10:19 ` chtz at informatik dot uni-bremen.de [this message]
2013-01-07 10:22 ` pinskia at gcc dot gnu.org
2015-02-19 15:27 ` jacob.benoit.1 at gmail dot com
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