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From: "hjl.tools at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/66703] [4.9/5/6] gcc.target/i386/readeflags-1.c aborts on -march=i586 or on -miamcu
Date: Tue, 07 Jul 2015 14:48:00 -0000 [thread overview]
Message-ID: <bug-66703-4-ACW8Tx1qS2@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-66703-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66703
--- Comment #3 from H.J. Lu <hjl.tools at gmail dot com> ---
(In reply to Yulia Koval from comment #2)
> Why zero-extend with and is better than zero-extend with movz? Why it's ok
> to clobber the flags?
According to Intel Pentium optimization guide, zero-extend with and is
faster than zero-extend with movz. It is OK to clobber EFLAGS to do
unsigned int x = (unsigned int) b;
where b is a boolean value.
next prev parent reply other threads:[~2015-07-07 14:48 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-30 12:01 [Bug target/66703] New: [4.9] gcc.target/i386/readeflags-1.c aborts on -march=i586 julia.koval at intel dot com
2015-07-04 14:24 ` [Bug target/66703] [4.9/5/6] gcc.target/i386/readeflags-1.c aborts on -march=i586 or on -miamcu hjl.tools at gmail dot com
2015-07-07 9:18 ` julia.koval at intel dot com
2015-07-07 14:48 ` hjl.tools at gmail dot com [this message]
2015-07-10 8:49 ` ubizjak at gmail dot com
2015-07-10 12:43 ` hjl.tools at gmail dot com
2015-07-10 15:33 ` uros at gcc dot gnu.org
2015-07-17 16:31 ` uros at gcc dot gnu.org
2015-07-17 18:46 ` uros at gcc dot gnu.org
2015-07-17 18:53 ` ubizjak at gmail dot com
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