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From: "pinskia at gcc dot gnu.org" <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 04:27:00 -0000	[thread overview]
Message-ID: <bug-53900-4-wUqsI8Rq5g@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 #6 from Andrew Pinski <pinskia at gcc dot gnu.org> 2013-01-07 04:25:38 UTC ---
>  __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.


  parent reply	other threads:[~2013-01-07  4:27 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 [this message]
2013-01-07 10:19 ` chtz at informatik dot uni-bremen.de
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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