Date: Tue, 12 Jun 2012 08:37:34 +0300 From: Andriy Gapon <avg@FreeBSD.org> To: perryh@pluto.rain.com Cc: freebsd-hackers@FreeBSD.org, rysto32@gmail.com, freebsd-listen@fabiankeil.de Subject: Re: decoding of multi-byte nops in dtrace Message-ID: <4FD6D59E.5040809@FreeBSD.org> In-Reply-To: <4fd5cd2b.SwlSDIgKvkib2N6C%perryh@pluto.rain.com> References: <4FD490D5.1070207@FreeBSD.org> <20120610152721.3b627896@fabiankeil.de> <4FD4CD8B.1080803@FreeBSD.org> <CAFMmRNwURMy55acPGZfYWnNSCB8VUvqWExV27RhBqcZHVUY==A@mail.gmail.com> <4FD5109D.5090107@FreeBSD.org> <4fd5cd2b.SwlSDIgKvkib2N6C%perryh@pluto.rain.com>
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on 11/06/2012 06:49 perryh@pluto.rain.com said the following:
> Sounds as if DTrace could use an improvement to recognize and handle
> the tail call optimization, maybe something along the lines of:
>
> If a function has no otherwise-determined return probe
> and it contains a jump to the entry point of another function
> then it inherits that other function's return probe.
>
> I'd expect that to handle cases like
>
> int bar(...)
> {
> ...
> return baz;
> }
>
> int foo(...)
> {
> ...
> return bar(...);
> }
>
> (although probably not cases where the return in foo calls a
> function pointer). And no, I am not volunteering to add it --
> ENOTIME :(
(Open)Solaris fdt code for sparc already handles this case (last instruction in
a function being a call), but not any other implementation.
Not sure if that is for technical reasons or if nobody just bothered.
--
Andriy Gapon
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