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Date: Mon, 11 Jun 2012 00:24:45 +0300
From: Andriy Gapon <avg@FreeBSD.org>
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To: Ryan Stone <rysto32@gmail.com>
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Cc: freebsd-hackers@FreeBSD.org, Fabian Keil <freebsd-listen@fabiankeil.de>
Subject: Re: decoding of multi-byte nops in dtrace
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on 10/06/2012 23:40 Ryan Stone said the following:
> On Sun, Jun 10, 2012 at 12:38 PM, Andriy Gapon <avg@freebsd.org> wrote:
>> Interesting observations, thank you.
>> Do you use -O2 or higher optimization for kernel/modules build?
>> I use only -O1.
>>
>> Here are some stats from my system:
>> $ dtrace -ln fbt::: | fgrep -c entry
>> 16876
>> $ dtrace -ln fbt::: | fgrep -c return
>> 16729
>>
>> So, 147 functions without return probe.
> 
> Try re-compiling with -foptimize-sibling-calls.  That enables the tail
> call optimization in gcc, and therefore you get many functions with no
> ret instruction (and thus no return probe in DTrace)

No, thank you :-)
I switched from -O2 to -O1 exactly for this reason (among a few others),
although -fno-optimize-sibling-calls would be a more targeted solution.

-- 
Andriy Gapon