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From: "gccbug at jamasaru dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c/52056] Code optimization sensitive to trivial changes
Date: Mon, 30 Jan 2012 23:17:00 -0000	[thread overview]
Message-ID: <bug-52056-4-1FVuvNwUIc@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-52056-4@http.gcc.gnu.org/bugzilla/>

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52056

--- Comment #1 from gccbug at jamasaru dot com 2012-01-30 22:34:37 UTC ---
While not relevant to gcc itself, it is interesting that clang also has trouble
with consistently identifying this optimization, but in an opposite way to GCC.
For clang, the unsigned shift code is faster (11.9 seconds) compared to clang's
signed shift (13.3 seconds.)   GCC's speeds are 24.3 and 11.3 seconds
respectively.   clang does not have any sensitivity to the static variable
declaration.


  reply	other threads:[~2012-01-30 22:34 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-01-30 20:02 [Bug c/52056] New: " gccbug at jamasaru dot com
2012-01-30 23:17 ` gccbug at jamasaru dot com [this message]
2012-01-31  1:04 ` [Bug middle-end/52056] " jakub at gcc dot gnu.org
2012-01-31 11:40 ` [Bug tree-optimization/52056] Vectorizer cost model is imprecise rguenth at gcc dot gnu.org
2012-07-13  8:52 ` rguenth at gcc dot gnu.org

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