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From: Roland McGrath <roland@hack.frob.com>
To: Torvald Riegel <triegel@redhat.com>
Cc: libc-ports@sourceware.org,    libc-alpha@sourceware.org
Subject: Re: PI mutex support for pthread_cond_* now in nptl
Date: Wed, 20 Feb 2013 22:04:00 -0000	[thread overview]
Message-ID: <20130220220421.25AA22C0A7@topped-with-meat.com> (raw)
In-Reply-To: Torvald Riegel's message of  Wednesday, 20 February 2013 21:25:26 +0100 <1361391926.581.1774.camel@triegel.csb>

At least the x86 assembly versions were written because the code produced
by GCC at the time was drastically worse.  But that was long ago.  We now
mandate compiling with GCC 4.3 or newer and recommend 4.6 or newer, so it
merits examining the code produced by those compilers and reconsidering the
judgments of the past.  But we will be conservative and not drop any
hand-written assembly unless recent compilers at -O2 are demonstrated to
produce code at least as good.  (Perhaps the reasonable standard is
something like at least as good from 4.6 -O3 and not a whole lot worse from
4.3 -O2.)  As time goes on, we can of course examine then-common compilers
and reconsider these judgments.  As of now, even 4.7 is not common yet.


Thanks,
Roland

  reply	other threads:[~2013-02-20 22:04 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-02-18 10:56 Siddhesh Poyarekar
2013-02-18 23:50 ` Joseph S. Myers
2013-02-19  0:50   ` Joseph S. Myers
2013-02-19 16:42 ` Richard Henderson
2013-02-19 16:49   ` Siddhesh Poyarekar
2013-02-19 17:18   ` Joseph S. Myers
2013-02-19 17:21     ` Siddhesh Poyarekar
2013-02-19 20:06     ` Torvald Riegel
2013-02-20 18:13       ` Steven Munroe
2013-02-20 20:25         ` Torvald Riegel
2013-02-20 22:04           ` Roland McGrath [this message]
2013-02-20 22:41           ` Steven Munroe
2013-02-21  4:32           ` Siddhesh Poyarekar
     [not found]     ` <1361304381.581.80.camel__6928.53579898856$1361304432$gmane$org@triegel.csb>
2013-02-22  4:11       ` Andi Kleen
     [not found] ` <5123AB55.2070100__45742.2411222526$1361292204$gmane$org@twiddle.net>
2013-02-19 17:01   ` Andreas Schwab
2013-02-19 17:18     ` Siddhesh Poyarekar
2013-02-19 17:39       ` Andreas Schwab
2013-02-19 17:52         ` Siddhesh Poyarekar

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