Add counters for write barriers in optimized code.

Add counters for write barriers in generated code.

R=hpayer@chromium.org

Committed: http://code.google.com/p/v8/source/detail?r=18029

[Hannes Payer (out of office), 2013-11-21 09:51:07]

Can we add these counters to MacroAssembler::RecordWrite?

[Michael Starzinger, 2013-11-21 14:42:17]

Should work, yes. Then they are no longer counting WBs just in optimized code,
but all of them. Which is fine, just a different measurement. I'll try to move
the counting into the RecordWrite macro later today.

[Hannes Payer (out of office), 2013-11-21 14:55:53]

On 2013/11/21 14:42:17, Michael Starzinger wrote:
> Should work, yes. Then they are no longer counting WBs just in optimized code,
> but all of them. Which is fine, just a different measurement. I'll try to move
> the counting into the RecordWrite macro later today.

Yes, I guess this is fine. Makes it more general.

[Michael Starzinger, 2013-11-21 20:38:44]

Done. PTAL.

[Hannes Payer (out of office), 2013-11-21 20:58:40]

LGTM, should we add it for arm as well?

[Michael Starzinger, 2013-11-21 21:20:03]

There is a shortage of scratch registers on ARM for this. The IncrementCounter
macro could be implement smarter to solve that though.

[Hannes Payer (out of office), 2013-11-22 07:34:02]

OK, can be done later on if needed.

[Michael Starzinger, 2013-11-22 17:37:43]

Committed patchset #3 manually as r18029 (presubmit successful).