RE: [RFA-new version][gdbserver] x86 agent expression bytecode compiler (speed up conditional tracepoints)

Pierre Muller
2010-06-20T17:02:40Z

> -----Message d'origine-----
> De : gdb-patches-owner@sourceware.org [mailto:gdb-patches-
> owner@sourceware.org] De la part de Doug Evans
> Envoyé : Sunday, June 20, 2010 5:31 PM
> À : Pierre Muller
> Cc : Hui Zhu; gdb-patches@sourceware.org; Pedro Alves; Stan Shebs; Eli
> Zaretskii; tromey@redhat.com; Michael Snyder
> Objet : Re: [RFA-new version][gdbserver] x86 agent expression bytecode
> compiler (speed up conditional tracepoints)
>
> On Sun, Jun 20, 2010 at 2:29 AM, Pierre Muller
> <pierre.muller@ics-cnrs.unistra.fr> wrote:
> >  As I said in a previous email, Ian's patch didn't work for me.
> > http://sourceware.org/ml/gdb-patches/2010-06/msg00424.html
>
> That's weird.
> Ian's approach involves removing the "if-always-true" test completely
> leaving just an asm.
> Can you send me the patch of Ian's that you tried?

I probably did a mistake indeed in my first try.
As it was not a patch to apply, I just modify the source directly,
and I suppose that I added the `do while (0)',
but forgot to remove the 'if (always_true ()) ' part, which would
explain why it works now and failed when I tried first...
Sorry about that false alarm...

Consider my RFA as withdrawn (see below),
but please it would be nice to get ASAP a patch in
that allows again to use the standard gdb_tester.sh script.
I cannot test any patch currently on gcc16 because gdbserver
compilation always fails.

> >  I propose here another small patch that fixes the linking failure.
> > Using a volatile variable, it explicitly forbids the compiler
> > to optimize out code by forbidding the assumption that this value
> will
> > never change.
> >
> >  This works on gcc16, an the approach seems reasonable.
>
> That's my patch. :-)

Sorry, I didn't read the whole thread, as I am not really interested in
this fast tracepoint feature.

> http://sourceware.org/ml/gdb-patches/2010-06/msg00374.html

Sorry for resubmitting a patch same as your, but
at least it is as if I voted for your patch too!

Pierre