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Re: profiling on sh
- From: Alexandre Oliva <aoliva at redhat dot com>
- To: kewarken at qnx dot com
- Cc: "Stephen Clarke" <Stephen dot Clarke at st dot com>, <gcc at gcc dot gnu dot org>
- Date: 16 Mar 2002 15:16:43 -0300
- Subject: Re: profiling on sh
- Organization: GCC Team, Red Hat
- References: <200203161351.IAA30154@hub.ott.qnx.com>
On Mar 16, 2002, kewarken@qnx.com wrote:
> That was part of my original question. What exactly is the trapa
> supposed to be doing?
It issues an exception, whose handler is presumably set by whatever
mini-OS/program loader this was designed for, this being the profiling
API of such mini-OS.
> I don't see a handler for that anywhere or know of how to set it up.
Me neither, I'm afraid. As far as I'm concerned, we don't have
profiling support on the SH. I wouldn't mind if someone revamped it
to put it more in line with other implementations of profiling. But
it would be best to get clearance with Jörn too, since I think he was
the last person who touched that code for real, back in 1997 (which
predates my involvement with the SH by 3 years :-). Jörn?
> I'd love to just be able to set trapa #33 to call mcount but I don't
> know where that would be done...OS level or code level.
OS level, for sure. It's the OS that's supposed to manipulate
interrupt handlers. As for how to set up such handlers, you may want
to have a look at the `Exceptions' section in one of the SH
programming manuals.
I'm pretty sure using a trap is the most efficient solution in terms
of code size, but I'm not sure it's as efficient in terms of not
affecting the performance of the running code. I'd expect traps to be
relatively expensive operations.
--
Alexandre Oliva Enjoy Guarana', see http://www.ic.unicamp.br/~oliva/
Red Hat GCC Developer aoliva@{cygnus.com, redhat.com}
CS PhD student at IC-Unicamp oliva@{lsd.ic.unicamp.br, gnu.org}
Free Software Evangelist Professional serial bug killer