From: Hans-Peter Nilsson <hp@bitrange.com>
To: Jonathan Wakely <jwakely@redhat.com>
Cc: Richard Henderson <rth@redhat.com>,
libstdc++@gcc.gnu.org, gcc-patches@gcc.gnu.org
Subject: Re: [libstdc++/65033] Give alignment info to libatomic
Date: Wed, 08 Apr 2015 03:58:00 -0000 [thread overview]
Message-ID: <alpine.BSF.2.02.1504072311520.89823@arjuna.pair.com> (raw)
In-Reply-To: <20150407150617.GH9755@redhat.com>
On Tue, 7 Apr 2015, Jonathan Wakely wrote:
> The docs are clear that alignof(s.x) is not related to its position in
> struct SoSo: https://gcc.gnu.org/onlinedocs/gcc/Alignment.html
>
> I'm not going to worry about that behaviour changing.
'kthen thanks, quite clear; I should have checked that myself.
BTW; I hope nobody uses alignof the atomic types for e.g. manual
memory management, because any inner alignment of the atomic
payload isn't exposed; they get the default alignment:
#include <atomic>
#include <iostream>
using std::cout;
using std::endl;
std::atomic_int ai;
std::atomic_llong all;
std::atomic_intmax_t aim;
int main(void)
{
cout << "alignof(ai): " << alignof(ai) << " .is_lock_free(): " << ai.is_lock_free() << endl;
}
alignof(ai): 1 .is_lock_free(): 1
I'd expect
alignof(ai): 4 .is_lock_free(): 1
No... wait, that's because atomic_base.h doesn't have the
natural-alignment fix, so it's still broken for
less-than-natural-alignment targets. But will be fixed?
brgds, H-P
next prev parent reply other threads:[~2015-04-08 3:58 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-02-12 21:23 Richard Henderson
2015-02-18 12:15 ` Jonathan Wakely
2015-03-25 16:22 ` Jonathan Wakely
2015-03-25 18:36 ` Richard Henderson
2015-03-25 18:49 ` Jonathan Wakely
2015-03-25 19:04 ` Richard Henderson
2015-03-26 13:21 ` Jonathan Wakely
2015-03-31 13:41 ` Jonathan Wakely
2015-03-31 14:54 ` Richard Henderson
2015-03-31 15:03 ` Jonathan Wakely
2015-03-31 15:13 ` Richard Henderson
2015-03-31 15:41 ` Jonathan Wakely
2015-04-06 22:59 ` Hans-Peter Nilsson
2015-04-13 4:45 ` patch fix issue 1 with "[libstdc++/65033] Give alignment info to libatomic" Hans-Peter Nilsson
2015-04-13 11:59 ` Jonathan Wakely
2015-04-13 5:59 ` Issue 2 " Hans-Peter Nilsson
2015-04-13 17:53 ` Joseph Myers
2015-03-25 18:39 ` [libstdc++/65033] Give alignment info to libatomic Richard Henderson
2015-04-03 3:04 ` Hans-Peter Nilsson
2015-03-26 11:54 ` Jonathan Wakely
2015-04-03 3:57 ` Hans-Peter Nilsson
2015-04-03 9:25 ` Hans-Peter Nilsson
2015-04-03 14:13 ` Jonathan Wakely
2015-04-03 19:13 ` Richard Henderson
2015-04-07 13:14 ` Jonathan Wakely
2015-04-09 11:17 ` Jonathan Wakely
2015-04-06 1:07 ` Hans-Peter Nilsson
2015-04-07 9:45 ` Jonathan Wakely
2015-04-07 10:52 ` Hans-Peter Nilsson
2015-04-07 13:12 ` Jonathan Wakely
2015-04-07 14:51 ` Hans-Peter Nilsson
2015-04-07 15:06 ` Jonathan Wakely
2015-04-08 3:58 ` Hans-Peter Nilsson [this message]
2015-04-08 9:35 ` Jonathan Wakely
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