Fix shared function info code replacement.

Fix shared function info code replacement.

This fixes a corner case when the unoptimized code for a shared function
info is replaced while the function is enqueued as a flushing candidate.
Since the link field is stored within the code object, the candidates
list got destroyed.

R=hpayer@chromium.org
BUG=v8:169209
TEST=cctest/test-heap/Regress169209

Committed: http://code.google.com/p/v8/source/detail?r=13361

[Hannes Payer (out of office), 2013-01-11 10:09:51]

https://codereview.chromium.org/11818052/diff/1/src/mark-compact.cc
File src/mark-compact.cc (right):

https://codereview.chromium.org/11818052/diff/1/src/mark-compact.cc#newcode946
src/mark-compact.cc:946: SharedFunctionInfo* next_candidate;
Why is there a difference between shared_info being the head of the list and
being somewhere on the list? Moreover can you unify the code below?

[Michael Starzinger, 2013-01-11 12:27:22]

PTAL.

https://codereview.chromium.org/11818052/diff/1/src/mark-compact.cc
File src/mark-compact.cc (right):

https://codereview.chromium.org/11818052/diff/1/src/mark-compact.cc#newcode946
src/mark-compact.cc:946: SharedFunctionInfo* next_candidate;
On 2013/01/11 10:09:51, Hannes Payer wrote:
> Why is there a difference between shared_info being the head of the list and
> being somewhere on the list? Moreover can you unify the code below?

The head needs to be handles specially, because it is stored as a field inside
the code-flusher (i.e. in the shared_function_info_candidates_head_ field).

https://codereview.chromium.org/11818052/diff/1/src/mark-compact.cc#newcode958
src/mark-compact.cc:958: ClearNextCandidate(shared_info);
As discussed offline, I added a break here.

https://codereview.chromium.org/11818052/diff/1/src/mark-compact.cc#newcode988
src/mark-compact.cc:988: ClearNextCandidate(function, undefined);
Likewise.

[Hannes Payer (out of office), 2013-01-11 12:39:10]

LGTM