Re: do not pass PR_INSTRUMENTEDCODE if there is no instrumentation

[Aldy Hernandez <aldyh at redhat dot com>]

Whoops, wrong patch.  This is the latest revision.

On 02/25/13 16:48, Aldy Hernandez wrote:
> On 02/22/13 11:27, Richard Henderson wrote:
> > On 02/21/2013 02:14 PM, Aldy Hernandez wrote:
> > > I suppose we could cheat and avoid passing PR_INSTRUMENTEDCODE if we
> > > ever enter expand_block_tm(), but perhaps we could do a little better as
> > > with the attached patch.
> >
> > I assume you meant "never enter" there.
> >
> > Yes, you don't need to "accumulate" GTMA_INSTRUMENTED_CODE.
> >
> > Probably what should happen is that either
> >
> > >                /* If we're sure to go irrevocable, there won't be
> > >                   anything to expand, since the run-time will go
> > >                   irrevocable right away.  */
> > >                if (sub & GTMA_DOES_GO_IRREVOCABLE
> > >                    && sub & GTMA_MAY_ENTER_IRREVOCABLE)
> > >                  continue;
> >
> > should in fact set EDGE_TM_UNINSTRUMENTED, or we should set that bit
> > even earlier
>
> I think it's best to do this here at tmmark time, instead of at IPA-tm.
>   Don't we have problems when ipa inlining runs after ipa_tm, thus
> creating more instrumented code later on?
>
> If so, the attached patch does it at tmmark.  I also cleaned up the
> instrumented edges, thus generating:
>
>    <bb 2>:
>    tm_state.2_5 = __builtin__ITM_beginTransaction (16458); [
> uninstrumentedCode hasNoAbort doesGoIrrevocable readOnly ]
>    __asm__ __volatile__("");
>    __builtin__ITM_commitTransaction ();
>
>    <bb 3>:
>    return;
>
> Which is way better than what we've ever generated... removing the
> alternative path altogether.  Yay.
>
> How does this look?
> Aldy
>
> > >        /* If we're sure to go irrevocable, don't transform anything.  */
> > >        if (d->irrevocable_blocks_normal
> > >            && bitmap_bit_p (d->irrevocable_blocks_normal,
> > >                             region->entry_block->index))
> > >          {
> > >            transaction_subcode_ior (region, GTMA_DOES_GO_IRREVOCABLE);
> > >            transaction_subcode_ior (region, GTMA_MAY_ENTER_IRREVOCABLE);
> > >            continue;
> > >          }
> >
> > And while we're at it, ipa_tm_scan_calls_transaction should probably add
> > a check to skip doing ipa_uninstrument_transaction on transactions that
> > have already been so marked.

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