From: Thomas Rodgers <rodgert@appliantology.com>
To: Hans-Peter Nilsson <hp@bitrange.com>
Cc: Thiago Macieira <thiago.macieira@intel.com>,
gcc-patches@gcc.gnu.org, libstdc++@gcc.gnu.org,
Andreas Schwab <schwab@linux-m68k.org>
Subject: Re: [PATCH 1/5] std::latch: reduce internal implementation from ptrdiff_t to int
Date: Mon, 01 Mar 2021 08:32:18 -0800 [thread overview]
Message-ID: <0f2e9a097045994d4b6575cbe3044cc1@appliantology.com> (raw)
In-Reply-To: <alpine.BSF.2.20.16.2102281629200.19516@arjuna.pair.com>
On 2021-02-28 13:31, Hans-Peter Nilsson wrote:
>> On Fri, 26 Feb 2021, Thiago Macieira via Gcc-patches wrote:
>>
>> On Friday, 26 February 2021 11:31:00 PST Andreas Schwab wrote: On Feb
>> 26 2021, Thiago Macieira wrote: On Friday, 26 February 2021 10:14:42
>> PST Andreas Schwab wrote: On Feb 26 2021, Thiago Macieira via
>> Gcc-patches wrote: - alignas(__alignof__(ptrdiff_t)) ptrdiff_t
>> _M_a;
>> + alignas(__alignof__(int)) int _M_a;
>> Futexes must be aligned to 4 bytes.
>>
>> Agreed, but doesn't this accomplish that?
> No. It uses whatever alignment the type already has, and is an
> elaborate no-op.
> I thought so too when I read the original line. But I expected it was
> written
> like that for a reason, especially since the same pattern appears in
> other
> places.
> I can change to "alignas(4)" (which is a GCC extension, I believe). Is
> that
> the correct solution?
> IMNSHO make use of the corresponding atomic type. Then there'd
> be no need for separate what's-the-right-align-curse games.
There is no predicate wait on atomic<T>.
> brgds, H-P
next prev parent reply other threads:[~2021-03-01 16:32 UTC|newest]
Thread overview: 73+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-25 22:50 C++2a synchronisation inefficient in GCC 11 Thiago Macieira
2021-02-26 11:19 ` Jonathan Wakely
2021-02-26 17:37 ` Thiago Macieira
2021-02-26 18:29 ` Jonathan Wakely
2021-02-26 19:30 ` Ville Voutilainen
2021-02-26 21:17 ` Jonathan Wakely
2021-02-26 21:18 ` Ville Voutilainen
2021-02-26 21:39 ` Jonathan Wakely
2021-02-26 18:47 ` Ville Voutilainen
2021-02-26 23:53 ` Thiago Macieira
2021-02-26 23:58 ` Ville Voutilainen
2021-02-27 0:11 ` Thiago Macieira
2021-02-27 0:18 ` Ville Voutilainen
2021-02-27 0:36 ` Thiago Macieira
2021-02-27 0:44 ` Ville Voutilainen
2021-02-27 0:53 ` Thiago Macieira
2021-02-27 1:03 ` Ville Voutilainen
2021-03-03 14:30 ` Jonathan Wakely
2021-03-03 17:07 ` Thiago Macieira
2021-03-03 17:14 ` Jonathan Wakely
2021-02-27 0:22 ` Marc Glisse
2021-02-27 0:30 ` Ville Voutilainen
2021-02-27 0:43 ` Thiago Macieira
2021-03-03 14:24 ` Jonathan Wakely
2021-03-03 17:12 ` Thiago Macieira
2021-02-26 15:59 ` [PATCH 1/5] std::latch: reduce internal implementation from ptrdiff_t to int Thiago Macieira
2021-02-26 15:59 ` [PATCH 2/5] Atomic __platform_wait: accept any 32-bit type, not just int Thiago Macieira
2021-03-03 14:34 ` Jonathan Wakely
2021-03-03 16:21 ` Jonathan Wakely
2021-03-03 17:27 ` Thiago Macieira
2021-03-03 17:34 ` Ville Voutilainen
2021-03-03 17:41 ` Jonathan Wakely
2021-02-26 15:59 ` [PATCH 3/5] std::__atomic_wait: don't use __detail::__waiter with futex Thiago Macieira
2021-02-26 15:59 ` [PATCH 4/5] barrier: use int instead of unsigned char for the phase state Thiago Macieira
2021-02-28 15:05 ` Hans-Peter Nilsson
2021-03-01 16:28 ` Thomas Rodgers
2021-03-01 17:24 ` Thiago Macieira
2021-03-01 17:38 ` Thomas Rodgers
2021-03-01 17:40 ` Thomas Rodgers
2021-03-01 18:06 ` Thiago Macieira
2021-03-01 19:08 ` Thomas Rodgers
2021-03-01 18:12 ` Ville Voutilainen
2021-03-01 19:44 ` Thiago Macieira
2021-03-01 20:35 ` Ville Voutilainen
2021-03-01 21:54 ` Thiago Macieira
2021-03-01 22:04 ` Ville Voutilainen
2021-03-01 22:21 ` Thiago Macieira
2021-03-01 22:31 ` Ville Voutilainen
2021-03-01 22:40 ` Thiago Macieira
2021-02-26 15:59 ` [PATCH 5/5] barrier: optimise by not having the hasher in a loop Thiago Macieira
2021-03-03 14:36 ` Jonathan Wakely
2021-02-26 18:14 ` [PATCH 1/5] std::latch: reduce internal implementation from ptrdiff_t to int Andreas Schwab
2021-02-26 19:08 ` Thiago Macieira
2021-02-26 19:31 ` Andreas Schwab
2021-02-27 0:13 ` Thiago Macieira
2021-02-28 21:31 ` Hans-Peter Nilsson
2021-03-01 8:56 ` Richard Biener
2021-03-03 14:56 ` Jonathan Wakely
2021-03-03 15:02 ` Andreas Schwab
2021-03-03 15:10 ` Jonathan Wakely
2021-03-03 15:37 ` Hans-Peter Nilsson
2021-03-01 16:32 ` Thomas Rodgers [this message]
2021-03-03 14:34 ` Jonathan Wakely
2021-03-03 17:14 ` Thiago Macieira
2021-03-03 17:18 ` Jonathan Wakely
2021-02-27 1:13 ` C++2a synchronisation inefficient in GCC 11 Thomas Rodgers
2021-02-27 1:29 ` Thomas Rodgers
2021-02-27 3:01 ` Thomas Rodgers
2021-03-01 17:46 ` Thomas Rodgers
2021-03-01 18:00 ` Thiago Macieira
2021-03-01 18:34 ` Thomas Rodgers
2021-03-01 19:11 ` Thiago Macieira
2021-02-27 2:02 ` Ville Voutilainen
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