Add pretenuring support to HAllocateObject.

Add pretenuring support to HAllocateObject.


BUG=

[Hannes Payer (out of office), 2013-05-23 09:32:27]

https://codereview.chromium.org/15734002/diff/8001/src/flag-definitions.h
File src/flag-definitions.h (right):

https://codereview.chromium.org/15734002/diff/8001/src/flag-definitions.h#new...
src/flag-definitions.h:196: DEFINE_bool(pretenure_hallocateobject, false,
"pretenure HAllocateObject")
This currently tanks performance. We will enable it as soon as we have
allocation site support.

[mvstanton, 2013-05-23 12:47:46]

Hi Hannes, lgtm, though one comment, see if it's addressable.

https://codereview.chromium.org/15734002/diff/8001/src/hydrogen-instructions.h
File src/hydrogen-instructions.h (right):

https://codereview.chromium.org/15734002/diff/8001/src/hydrogen-instructions....
src/hydrogen-instructions.h:4878: static Flags DefaultFlags() {
It would be nice if these ~20 lines could be shared with the similar lines in
HAllocate. If it is straightforward to make a base class for those two hydrogen
instructions, I would say do it.

[Michael Starzinger, 2013-05-23 14:50:18]

As discussed offline: I don't think we should put more work into HAllocateObject
but rather get rid of it and model it using HAllocate and a sequence if
HStoreNamedField instructions. This would reduce complexity.

[Hannes Payer (out of office), 2013-05-23 15:02:08]

On 2013/05/23 14:50:18, Michael Starzinger wrote:
> As discussed offline: I don't think we should put more work into
HAllocateObject
> but rather get rid of it and model it using HAllocate and a sequence if
> HStoreNamedField instructions. This would reduce complexity.

I agree, we should get rid of it.