HeapProfiler: Make strings unique in HeapProfile.

HeapProfiler: replace pointer based matching algorithm with string matching algorithm for strings_ member.

pros: decreased snapshot size.
cons: increased serialization time.

I've tested the implementation on gmail 90mb heap.
I saw no speed degradation on the serialization step.
The snapshot size lost ~3% of its size. 100Mb -> 97Mb.

BUG=none
R=alph@chromium.org, yangguo@chromium.org

Committed: https://code.google.com/p/v8/source/detail?r=16725

[alph, 2013-09-16 08:23:49]

https://codereview.chromium.org/24120006/diff/1/src/heap-snapshot-generator.h
File src/heap-snapshot-generator.h (right):

https://codereview.chromium.org/24120006/diff/1/src/heap-snapshot-generator.h...
src/heap-snapshot-generator.h:646: uint32_t len = strlen(s);
Would be nice to have a type cast here. Otherwise it might cause error/warning
on x64 (Win64 in particular).

Also consider using int instead as HashSequentialString accepts int.

[loislo, 2013-09-16 08:55:51]

On 2013/09/16 08:23:49, alph wrote:
> https://codereview.chromium.org/24120006/diff/1/src/heap-snapshot-generator.h
> File src/heap-snapshot-generator.h (right):
> 
>
https://codereview.chromium.org/24120006/diff/1/src/heap-snapshot-generator.h...
> src/heap-snapshot-generator.h:646: uint32_t len = strlen(s);
> Would be nice to have a type cast here. Otherwise it might cause error/warning
> on x64 (Win64 in particular).
> 
> Also consider using int instead as HashSequentialString accepts int.

done

[alph, 2013-09-16 08:59:05]

lgtm

[Yang, 2013-09-16 09:15:06]

On 2013/09/16 09:08:46, loislo wrote:

lgtm

[loislo, 2013-09-16 09:16:12]

Committed patchset #2 manually as r16725 (presubmit successful).