Fix code flusher to process weak function links.

Fix code flusher to process weak function links.

This fixes a corner case where weak function links of the code flushing
candidates list were destroyed by scavenges that happened during
incremental marking. Now those weak function links are updated while
scavenging happens.

R=ulan@chromium.org
TEST=cctest/test-heap/TestCodeFlushingIncrementalScavenge

Committed: https://code.google.com/p/v8/source/detail?r=12825

[ulan_google, 2012-10-26 09:15:28]

LGTM

https://codereview.chromium.org/11271006/diff/2002/src/mark-compact.cc
File src/mark-compact.cc (right):

https://codereview.chromium.org/11271006/diff/2002/src/mark-compact.cc#newcod...
src/mark-compact.cc:964: candidate = GetNextCandidate(*slot);
candidate = GetNextCandidate(candidate);

Would be more robust w.r.t. reordering of these two lines.

[Michael Starzinger, 2012-10-26 09:39:39]

https://codereview.chromium.org/11271006/diff/2002/src/mark-compact.cc
File src/mark-compact.cc (right):

https://codereview.chromium.org/11271006/diff/2002/src/mark-compact.cc#newcod...
src/mark-compact.cc:964: candidate = GetNextCandidate(*slot);
On 2012/10/26 09:15:28, ulan1 wrote:
> candidate = GetNextCandidate(candidate);
> 
> Would be more robust w.r.t. reordering of these two lines.

We cannot use the candidate variable here, because the visitor most probably
updated the referenced stored at the slot. So we need to reload the reference
and candidate should be considered a stale value at this point.