Execute a memory barrier when adding a new page to a space to synchronize access with concurrent sw…

Execute a memory barrier when adding a new page to a space to synchronize access with concurrent sweepers.


BUG=

Committed: https://code.google.com/p/v8/source/detail?r=13941

[Michael Starzinger, 2013-03-11 11:40:36]

LGTM, with reservations.

https://codereview.chromium.org/12342017/diff/1/src/spaces.cc
File src/spaces.cc (right):

https://codereview.chromium.org/12342017/diff/1/src/spaces.cc#newcode543
src/spaces.cc:543: MemoryBarrier();
As discussed in length offline: We agree that starting to spread memory barriers
through the code (outside of dedicated synchronized data structures) is a
slippery slope. But since we don't have a cleaner solution for this data
structure that is embedded into the memory chunks, I agree to this temporary
solution.

But please add a TODO here, that we should find a cleaner way to guarantee that
the page list can be expanded concurrently. You can even attribute that TODO to
my name if you like.

[Hannes Payer (out of office), 2013-03-14 09:15:44]

Committed patchset #3 manually as r13941 (presubmit successful).