Make it possible to assert that certain instance types are compatible wrt HAllocate.

Make it possible to assert that certain instance types are compatible wrt HAllocate.

Turns clear_next_map_word_ into a flag and adds a new method
CompatibleInstanceTypes(). This is used in BuildUncheckedStringAdd()
to ASSERT that there's no difference wrt. HAllocate in using
CONS_STRING_TYPE vs CONS_ASCII_STRING_TYPE.

R=mvstanton@chromium.org

Committed: https://code.google.com/p/v8/source/detail?r=18428

[Benedikt Meurer, 2013-12-11 12:46:04]

Hey Michael,
Here's the HAllocate flags cleanup you suggested in
https://codereview.chromium.org/106453003/. Pretty much straight-forward. 
PTAL
-- Benedikt

[mvstanton, 2013-12-11 13:03:21]

Cool, one comment to address and LGTM.
--Michael

https://codereview.chromium.org/110443003/diff/1/src/hydrogen-instructions.cc
File src/hydrogen-instructions.cc (right):

https://codereview.chromium.org/110443003/diff/1/src/hydrogen-instructions.cc...
src/hydrogen-instructions.cc:3497: (flags_ & CLEAR_NEXT_MAP_WORD));
Put this into an inline setter.

[Benedikt Meurer, 2013-12-11 13:43:40]

https://codereview.chromium.org/110443003/diff/1/src/hydrogen-instructions.cc
File src/hydrogen-instructions.cc (right):

https://codereview.chromium.org/110443003/diff/1/src/hydrogen-instructions.cc...
src/hydrogen-instructions.cc:3497: (flags_ & CLEAR_NEXT_MAP_WORD));
On 2013/12/11 13:03:21, mvstanton wrote:
> Put this into an inline setter.

Done.

[Benedikt Meurer, 2013-12-11 13:50:06]

Hey guys, here's the updated code as discussed offline.

[mvstanton, 2013-12-11 14:16:36]

That still works for me.

[Benedikt Meurer, 2014-01-02 06:26:50]

Committed patchset #3 manually as r18428 (presubmit successful).