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From: "jfb at chromium dot org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/66881] Possibly inefficient std::atomic<int> codegen on x86 for simple arithmetic
Date: Mon, 20 Jul 2015 21:57:00 -0000	[thread overview]
Message-ID: <bug-66881-4-UcHARZTDjX@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-66881-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66881

JF Bastien <jfb at chromium dot org> changed:

           What    |Removed                     |Added
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                 CC|                            |jfb at chromium dot org

--- Comment #6 from JF Bastien <jfb at chromium dot org> ---
I don't think this is a duplicate of PR 50677: this issue uses two *separate*
atomic operations, which inherently aren't atomic, whereas PR 50677 uses a
single volatile operations which some (misguided) developers expect to be
atomic.

The compiler may decide to be nice to developers who have misguided
expectations from using volatile, but this example clearly uses separate
load/store operations. I believe Thomas is correct: the code for f() should
codegen the same code as g().


      parent reply	other threads:[~2015-07-20 21:57 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-07-15 16:05 [Bug middle-end/66881] New: " tkoeppe at google dot com
2015-07-15 16:23 ` [Bug middle-end/66881] " hjl.tools at gmail dot com
2015-07-15 16:29 ` ville.voutilainen at gmail dot com
2015-07-15 16:30 ` hjl.tools at gmail dot com
2015-07-15 16:37 ` hjl.tools at gmail dot com
2015-07-15 16:37 ` hjl.tools at gmail dot com
2015-07-20 21:57 ` jfb at chromium dot org [this message]

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