Bug 187437 – [JSC] Optimize layout of SymbolTable to reduce padding

• Status: RESOLVED
• Resolution: FIXED
• Component: New Bugs

[Yusuke Suzuki]

[JSC] Optimize layout of SymbolTable to reduce padding

[Yusuke Suzuki]

Created attachment 344525 [details]
Patch

[Mark Lam]

Comment on attachment 344525 [details]
Patch

r=me

[WebKit Commit Bot]

Comment on attachment 344525 [details]
Patch

Rejecting attachment 344525 [details] from commit-queue.

Failed to run "['/Volumes/Data/EWS/WebKit/Tools/Scripts/webkit-patch', '--status-host=webkit-queues.webkit.org', '--bot-id=webkit-cq-02', 'land-attachment', '--force-clean', '--non-interactive', '--parent-command=commit-queue', 344525, '--port=mac']" exit_code: 2 cwd: /Volumes/Data/EWS/WebKit

Logging in as [e-mail]...
Fetching: https://bugs.webkit.org/attachment.cgi?id=344525&action=edit
Fetching: https://bugs.webkit.org/show_bug.cgi?id=187437&ctype=xml&excludefield=attachmentdata
Processing 1 patch from 1 bug.
Updating working directory
Processing patch 344525 from bug 187437.
Fetching: https://bugs.webkit.org/attachment.cgi?id=344525
Failed to run "['git', 'svn', 'dcommit', '--rmdir']" exit_code: 1 cwd: /Volumes/Data/EWS/WebKit

Committing to http://svn.webkit.org/repository/webkit/trunk ...
	M	Source/JavaScriptCore/ChangeLog

ERROR from SVN:
Item is out of date: File '/trunk/Source/JavaScriptCore/ChangeLog' is out of date
W: 9275b13b53daac58e42e9cb6f9b6eaceea6bf497 and refs/remotes/origin/master differ, using rebase:
:040000 040000 3791fe035b112bc47a3de7dea08c289b80d8040b d2d5b5667dcd84554ec6d384dbe77d5eeb0d8e5c M	Source
Current branch master is up to date.
ERROR: Not all changes have been committed into SVN, however the committed
ones (if any) seem to be successfully integrated into the working tree.
Please see the above messages for details.


Failed to run "['git', 'svn', 'dcommit', '--rmdir']" exit_code: 1 cwd: /Volumes/Data/EWS/WebKit

Committing to http://svn.webkit.org/repository/webkit/trunk ...
	M	Source/JavaScriptCore/ChangeLog

ERROR from SVN:
Item is out of date: File '/trunk/Source/JavaScriptCore/ChangeLog' is out of date
W: 9275b13b53daac58e42e9cb6f9b6eaceea6bf497 and refs/remotes/origin/master differ, using rebase:
:040000 040000 3791fe035b112bc47a3de7dea08c289b80d8040b d2d5b5667dcd84554ec6d384dbe77d5eeb0d8e5c M	Source
Current branch master is up to date.
ERROR: Not all changes have been committed into SVN, however the committed
ones (if any) seem to be successfully integrated into the working tree.
Please see the above messages for details.


Failed to run "['git', 'svn', 'dcommit', '--rmdir']" exit_code: 1 cwd: /Volumes/Data/EWS/WebKit
Updating OpenSource
From https://git.webkit.org/git/WebKit
   b9585f197cc..28ef0a0651a  master     -> origin/master
Partial-rebuilding .git/svn/refs/remotes/origin/master/.rev_map.268f45cc-cd09-0410-ab3c-d52691b4dbfc ...
Currently at 233616 = b9585f197cca3cb59b51c5003895d1d34140a2f1
r233620 = 28ef0a0651af6a904f78aefd20ed11387d4095c8
Done rebuilding .git/svn/refs/remotes/origin/master/.rev_map.268f45cc-cd09-0410-ab3c-d52691b4dbfc
First, rewinding head to replay your work on top of it...
Fast-forwarded master to refs/remotes/origin/master.

Full output: https://webkit-queues.webkit.org/results/8468693

[WebKit Commit Bot]

Comment on attachment 344525 [details]
Patch

Clearing flags on attachment: 344525

Committed r233622: <https://trac.webkit.org/changeset/233622>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.

[Radar WebKit Bug Importer]

<rdar://problem/41934653>

[Simon Fraser (smfr)]

I'm liking these padding optimizations. Are you using dump-class-layout?

[Yusuke Suzuki]

(In reply to Simon Fraser (smfr) from comment #7)
> I'm liking these padding optimizations. Are you using dump-class-layout?

Yeah, I saw your nice optimizations, and I'm attempting to perform these things in JSC's long-live objects!

[Simon Fraser (smfr)]

The most frequently-allocated JSC objects (that 'heap' shows with Malloc=1) are:

JSC::DirectJITCode
JSC::StructureStubClearingWatchpoint
JSC::CodeBlockJettisoningWatchpoint
JSC::LLIntPrototypeLoadAdaptiveStructureWatchpoint
JSC::ProxyableAccessCase
JSC::JITStubRoutine
JSC::NativeJITCode
JSC::AccessCase
JSC::GCAwareJITStubRoutine
JSC::GetterSetterAccessCase
JSC::StringSourceProvider
JSC::FunctionRareData::AllocationProfileClearingWatchpoint
JSC::WeakGCMap<std::__1::pair<WTF::UniquedStringImpl*
JSC::DFG::AdaptiveInferredPropertyValueWatchpoint
JSC::DFG::JITCode
JSC::DFG::AdaptiveStructureWatchpoint

so these are good targets for padding optimizations.

[Yusuke Suzuki]

(In reply to Simon Fraser (smfr) from comment #9)
> The most frequently-allocated JSC objects (that 'heap' shows with Malloc=1)
> are:
> 
> JSC::DirectJITCode
> JSC::StructureStubClearingWatchpoint
> JSC::CodeBlockJettisoningWatchpoint
> JSC::LLIntPrototypeLoadAdaptiveStructureWatchpoint
> JSC::ProxyableAccessCase
> JSC::JITStubRoutine
> JSC::NativeJITCode
> JSC::AccessCase
> JSC::GCAwareJITStubRoutine
> JSC::GetterSetterAccessCase
> JSC::StringSourceProvider
> JSC::FunctionRareData::AllocationProfileClearingWatchpoint
> JSC::WeakGCMap<std::__1::pair<WTF::UniquedStringImpl*
> JSC::DFG::AdaptiveInferredPropertyValueWatchpoint
> JSC::DFG::JITCode
> JSC::DFG::AdaptiveStructureWatchpoint
> 
> so these are good targets for padding optimizations.

That's nice! A bit unfortunate thing is that Instruments cannot get type information if the object does not have vtable pointer (runtime type information).
Is there any way to annotate allocation to inform the object lifetimes to Instruments (like, API to map address to name for Instruments)?
If we have such annotations, it is quite useful.

[Simon Fraser (smfr)]

(In reply to Yusuke Suzuki from comment #10)
> Is there any way to annotate allocation to inform the object lifetimes to
> Instruments (like, API to map address to name for Instruments)?
> If we have such annotations, it is quite useful.

I don't know of any, sadly.

[Saam Barati]

Maybe we could artificially give things we're interested in a VTable just for profiling purposes in some special build mode?