Filter out remembered slots that are at the start of an object.

Filter out remembered slots that are at the start of an object.

These slots are invalid and can result in a broken offset when slot index and start of object are equal and are at the beginning of a cell.

Moreover, make DCHECKs CHECKs to catch bugs in the wild.

BUG=chromium:473174
LOG=n

Committed: https://crrev.com/189b355a76ea5a26fba18e712f4849f0435e856b
Cr-Commit-Position: refs/heads/master@{#27602}

[Hannes Payer (out of office), 2015-04-02 17:56:41]

hpayer@chromium.org changed reviewers:
+ ishell@chromium.org, ulan@chromium.org

[Igor Sheludko, 2015-04-02 21:51:41]

lgtm with a nit:

https://codereview.chromium.org/1051243004/diff/1/src/heap/mark-compact.cc
File src/heap/mark-compact.cc (right):

https://codereview.chromium.org/1051243004/diff/1/src/heap/mark-compact.cc#ne...
src/heap/mark-compact.cc:3128: if ((cells[start_index] & index_in_cell) > 0) {
IMHO, it would be cleaner to write != 0.

[Hannes Payer (out of office), 2015-04-06 14:38:24]

https://codereview.chromium.org/1051243004/diff/1/src/heap/mark-compact.cc
File src/heap/mark-compact.cc (right):

https://codereview.chromium.org/1051243004/diff/1/src/heap/mark-compact.cc#ne...
src/heap/mark-compact.cc:3128: if ((cells[start_index] & index_in_cell) > 0) {
On 2015/04/02 21:51:41, Igor Sheludko wrote:
> IMHO, it would be cleaner to write != 0.

Done.

[Hannes Payer (out of office), 2015-04-06 14:38:27]

The CQ bit was checked by hpayer@chromium.org

[Hannes Payer (out of office), 2015-04-06 14:38:28]

The patchset sent to the CQ was uploaded after l-g-t-m from ishell@chromium.org
Link to the patchset: https://codereview.chromium.org/1051243004/#ps20001
(title: " ")

[commit-bot: I haz the power, 2015-04-06 14:38:31]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1051243004/20001

[commit-bot: I haz the power, 2015-04-06 14:58:13]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-04-06 14:58:23]

Patchset 2 (id:??) landed as
https://crrev.com/189b355a76ea5a26fba18e712f4849f0435e856b
Cr-Commit-Position: refs/heads/master@{#27602}