Bug 86436 – shrinkToFit() is often not called for Vectors in CodeBlock

• Component: JavaScriptCore
• Status: RESOLVED FIXED

[Simon Fraser (smfr)]

Data collected via bug 86281 show that a lot of vector capacity is wasted via the Vectors allocated here:

2200 vectors, 17.20KB used of 550.00KB, 532.80KB wasted at:
1   0x1069ac725 WTF::Vector<WTF::Vector<JSC::RareCaseProfile, 8ul>*, 32ul>::Vector()
2   0x1069abf25 WTF::Vector<WTF::Vector<JSC::RareCaseProfile, 8ul>*, 32ul>::Vector()
3   0x1069abeb6 WTF::SegmentedVector<JSC::RareCaseProfile, 8ul>::SegmentedVector()
4   0x10699c805 WTF::SegmentedVector<JSC::RareCaseProfile, 8ul>::SegmentedVector()
5   0x1069958d1 JSC::CodeBlock::CodeBlock(JSC::ScriptExecutable*, JSC::CodeType, JSC::JSGlobalObject*, WTF::PassRefPtr<JSC::SourceProvider>, unsigned int, WTF::HashMap<WTF::RefPtr<WTF::StringImpl>, JSC::SymbolTableEntry, JSC::IdentifierRepHash, WTF::HashTraits<WTF::RefPtr<WTF::StringImpl> >, JSC::SymbolTableIndexHashTraits>*, bool, WTF::PassOwnPtr<JSC::CodeBlock>)

2200 vectors, 20.92KB used of 550.00KB, 529.08KB wasted at:
1   0x1069ad1b5 WTF::Vector<WTF::Vector<JSC::LLIntCallLinkInfo, 8ul>*, 32ul>::Vector()
2   0x1069ad135 WTF::Vector<WTF::Vector<JSC::LLIntCallLinkInfo, 8ul>*, 32ul>::Vector()
3   0x1069ad0e6 WTF::SegmentedVector<JSC::LLIntCallLinkInfo, 8ul>::SegmentedVector()
4   0x10699c675 WTF::SegmentedVector<JSC::LLIntCallLinkInfo, 8ul>::SegmentedVector()
5   0x1069957a1 JSC::CodeBlock::CodeBlock(JSC::ScriptExecutable*, JSC::CodeType, JSC::JSGlobalObject*, WTF::PassRefPtr<JSC::SourceProvider>, unsigned int, WTF::HashMap<WTF::RefPtr<WTF::StringImpl>, JSC::SymbolTableEntry, JSC::IdentifierRepHash, WTF::HashTraits<WTF::RefPtr<WTF::StringImpl> >, JSC::SymbolTableIndexHashTraits>*, bool, WTF::PassOwnPtr<JSC::CodeBlock>)

2200 vectors, 21.14KB used of 550.00KB, 528.86KB wasted at:
1   0x1069ac725 WTF::Vector<WTF::Vector<JSC::RareCaseProfile, 8ul>*, 32ul>::Vector()
2   0x1069abf25 WTF::Vector<WTF::Vector<JSC::RareCaseProfile, 8ul>*, 32ul>::Vector()
3   0x1069abeb6 WTF::SegmentedVector<JSC::RareCaseProfile, 8ul>::SegmentedVector()
4   0x10699c805 WTF::SegmentedVector<JSC::RareCaseProfile, 8ul>::SegmentedVector()
5   0x1069958be JSC::CodeBlock::CodeBlock(JSC::ScriptExecutable*, JSC::CodeType, JSC::JSGlobalObject*, WTF::PassRefPtr<JSC::SourceProvider>, unsigned int, WTF::HashMap<WTF::RefPtr<WTF::StringImpl>, JSC::SymbolTableEntry, JSC::IdentifierRepHash, WTF::HashTraits<WTF::RefPtr<WTF::StringImpl> >, JSC::SymbolTableIndexHashTraits>*, bool, WTF::PassOwnPtr<JSC::CodeBlock>)

2200 vectors, 43.21KB used of 550.47KB, 507.26KB wasted at:
1   0x1069aca05 WTF::Vector<WTF::Vector<JSC::ValueProfile, 8ul>*, 32ul>::Vector()
2   0x1069ac985 WTF::Vector<WTF::Vector<JSC::ValueProfile, 8ul>*, 32ul>::Vector()
3   0x1069ac936 WTF::SegmentedVector<JSC::ValueProfile, 8ul>::SegmentedVector()
4   0x10699c7e5 WTF::SegmentedVector<JSC::ValueProfile, 8ul>::SegmentedVector()
5   0x1069958ab JSC::CodeBlock::CodeBlock(JSC::ScriptExecutable*, JSC::CodeType, JSC::JSGlobalObject*, WTF::PassRefPtr<JSC::SourceProvider>, unsigned int, WTF::HashMap<WTF::RefPtr<WTF::StringImpl>, JSC::SymbolTableEntry, JSC::IdentifierRepHash, WTF::HashTraits<WTF::RefPtr<WTF::StringImpl> >, JSC::SymbolTableIndexHashTraits>*, bool, WTF::PassOwnPtr<JSC::CodeBlock>)

1996 vectors, 323.72KB used of 665.81KB, 342.09KB wasted at:
1   0x1069acf45 WTF::Vector<JSC::StructureStubInfo, 0ul>::Vector()
2   0x10699c6b5 WTF::Vector<JSC::StructureStubInfo, 0ul>::Vector()
3   0x1069957c7 JSC::CodeBlock::CodeBlock(JSC::ScriptExecutable*, JSC::CodeType, JSC::JSGlobalObject*, WTF::PassRefPtr<JSC::SourceProvider>, unsigned int, WTF::HashMap<WTF::RefPtr<WTF::StringImpl>, JSC::SymbolTableEntry, JSC::IdentifierRepHash, WTF::HashTraits<WTF::RefPtr<WTF::StringImpl> >, JSC::SymbolTableIndexHashTraits>*, bool, WTF::PassOwnPtr<JSC::CodeBlock>)
4   0x106a9ea22 JSC::FunctionCodeBlock::FunctionCodeBlock(JSC::FunctionExecutable*, JSC::CodeType, JSC::JSGlobalObject*, WTF::PassRefPtr<JSC::SourceProvider>, unsigned int, bool, WTF::PassOwnPtr<JSC::CodeBlock>)
5   0x106a97ab8 JSC::FunctionCodeBlock::FunctionCodeBlock(JSC::FunctionExecutable*, JSC::CodeType, JSC::JSGlobalObject*, WTF::PassRefPtr<JSC::SourceProvider>, unsigned int, bool, WTF::PassOwnPtr<JSC::CodeBlock>)

1996 vectors, 102.31KB used of 372.38KB, 270.06KB wasted at:
1   0x1069ace65 WTF::Vector<JSC::CallLinkInfo, 0ul>::Vector()
2   0x10699c705 WTF::Vector<JSC::CallLinkInfo, 0ul>::Vector()
3   0x1069957ed JSC::CodeBlock::CodeBlock(JSC::ScriptExecutable*, JSC::CodeType, JSC::JSGlobalObject*, WTF::PassRefPtr<JSC::SourceProvider>, unsigned int, WTF::HashMap<WTF::RefPtr<WTF::StringImpl>, JSC::SymbolTableEntry, JSC::IdentifierRepHash, WTF::HashTraits<WTF::RefPtr<WTF::StringImpl> >, JSC::SymbolTableIndexHashTraits>*, bool, WTF::PassOwnPtr<JSC::CodeBlock>)
4   0x106a9ea22 JSC::FunctionCodeBlock::FunctionCodeBlock(JSC::FunctionExecutable*, JSC::CodeType, JSC::JSGlobalObject*, WTF::PassRefPtr<JSC::SourceProvider>, unsigned int, bool, WTF::PassOwnPtr<JSC::CodeBlock>)
5   0x106a97ab8 JSC::FunctionCodeBlock::FunctionCodeBlock(JSC::FunctionExecutable*, JSC::CodeType, JSC::JSGlobalObject*, WTF::PassRefPtr<JSC::SourceProvider>, unsigned int, bool, WTF::PassOwnPtr<JSC::CodeBlock>)



1996 vectors, 57.59KB used of 276.23KB, 218.64KB wasted at:
1   0x1069acd65 WTF::Vector<JSC::MethodCallLinkInfo, 0ul>::Vector()
2   0x10699c725 WTF::Vector<JSC::MethodCallLinkInfo, 0ul>::Vector()
3   0x106995800 JSC::CodeBlock::CodeBlock(JSC::ScriptExecutable*, JSC::CodeType, JSC::JSGlobalObject*, WTF::PassRefPtr<JSC::SourceProvider>, unsigned int, WTF::HashMap<WTF::RefPtr<WTF::StringImpl>, JSC::SymbolTableEntry, JSC::IdentifierRepHash, WTF::HashTraits<WTF::RefPtr<WTF::StringImpl> >, JSC::SymbolTableIndexHashTraits>*, bool, WTF::PassOwnPtr<JSC::CodeBlock>)
4   0x106a9ea22 JSC::FunctionCodeBlock::FunctionCodeBlock(JSC::FunctionExecutable*, JSC::CodeType, JSC::JSGlobalObject*, WTF::PassRefPtr<JSC::SourceProvider>, unsigned int, bool, WTF::PassOwnPtr<JSC::CodeBlock>)
5   0x106a97ab8 JSC::FunctionCodeBlock::FunctionCodeBlock(JSC::FunctionExecutable*, JSC::CodeType, JSC::JSGlobalObject*, WTF::PassRefPtr<JSC::SourceProvider>, unsigned int, bool, WTF::PassOwnPtr<JSC::CodeBlock>)


2200 vectors, 380.47KB used of 550.00KB, 169.53KB wasted at:
1   0x106985f15 WTF::Vector<JSC::ValueProfile, 8ul>::Vector()
2   0x106985d35 WTF::Vector<JSC::ValueProfile, 8ul>::Vector()
3   0x1069ac924 WTF::SegmentedVector<JSC::ValueProfile, 8ul>::SegmentedVector()
4   0x10699c7e5 WTF::SegmentedVector<JSC::ValueProfile, 8ul>::SegmentedVector()
5   0x1069958ab JSC::CodeBlock::CodeBlock(JSC::ScriptExecutable*, JSC::CodeType, JSC::JSGlobalObject*, WTF::PassRefPtr<JSC::SourceProvider>, unsigned int, WTF::HashMap<WTF::RefPtr<WTF::StringImpl>, JSC::SymbolTableEntry, JSC::IdentifierRepHash, WTF::HashTraits<WTF::RefPtr<WTF::StringImpl> >, JSC::SymbolTableIndexHashTraits>*, bool, WTF::PassOwnPtr<JSC::CodeBlock>)

[Filip Pizlo]

*** Bug 86437 has been marked as a duplicate of this bug. ***

[Filip Pizlo]

*** Bug 86435 has been marked as a duplicate of this bug. ***

[Filip Pizlo]

Created attachment 142058 [details]
the patch

[Filip Pizlo]

Created attachment 142061 [details]
the patch

Decided to write a comment clearly defining what I mean by "EarlyShrink" and "LateShrink".

[Filip Pizlo]

Created attachment 142062 [details]
the patch

Realized that it might be a good idea to have a change log for WTF.

[Oliver Hunt]

Comment on attachment 142062 [details]
the patch

View in context: https://bugs.webkit.org/attachment.cgi?id=142062&action=review

> Source/JavaScriptCore/bytecode/CodeBlock.cpp:2130
>          m_rareData->m_lineInfo.shrinkToFit();

I think we always have line info now -- it seems we should pull it out of rareData so we're not unnecessarily creating what is intended to be an uncommon allocation.

> Source/JavaScriptCore/bytecode/CodeBlock.cpp:2136
> +        m_rareData->m_callReturnIndexVector.shrinkToFit();
> +#endif
> +#if ENABLE(DFG_JIT)
> +        m_rareData->m_inlineCallFrames.shrinkToFit();
> +        m_rareData->m_codeOrigins.shrinkToFit();

Ditto for these -- do we want a lazily instantiated m_jitData member perhaps?

[Filip Pizlo]

(In reply to comment #6)
> (From update of attachment 142062 [details])
> View in context: https://bugs.webkit.org/attachment.cgi?id=142062&action=review
> 
> > Source/JavaScriptCore/bytecode/CodeBlock.cpp:2130
> >          m_rareData->m_lineInfo.shrinkToFit();
> 
> I think we always have line info now -- it seems we should pull it out of rareData so we're not unnecessarily creating what is intended to be an uncommon allocation.
> 
> > Source/JavaScriptCore/bytecode/CodeBlock.cpp:2136
> > +        m_rareData->m_callReturnIndexVector.shrinkToFit();
> > +#endif
> > +#if ENABLE(DFG_JIT)
> > +        m_rareData->m_inlineCallFrames.shrinkToFit();
> > +        m_rareData->m_codeOrigins.shrinkToFit();
> 
> Ditto for these -- do we want a lazily instantiated m_jitData member perhaps?

Separate patch for both?

[Build Bot]

Comment on attachment 142062 [details]
the patch

Attachment 142062 [details] did not pass win-ews (win):
Output: http://queues.webkit.org/results/12694792

[Filip Pizlo]

Created attachment 142108 [details]
patch for EWS

[Filip Pizlo]

Landed in http://trac.webkit.org/changeset/117198

[Simon Fraser (smfr)]

Even after this change I see a lot of wasted capacity under:


1   0x108813e54 WTF::SegmentedVector<JSC::RareCaseProfile, 8ul>::SegmentedVector()
2   0x10880c43d JSC::CodeBlock::CodeBlock(JSC::ScriptExecutable*, JSC::CodeType, JSC::JSGlobalObject*, WTF::PassRefPtr<JSC::SourceProvider>, unsigned int, WTF::HashMap<WTF::RefPtr<WTF::StringImpl>, JSC::SymbolTableEntry, JSC::IdentifierRepHash, WTF::HashTraits<WTF::RefPtr<WTF::StringImpl> >, JSC::SymbolTableIndexHashTraits>*, bool, WTF::PassOwnPtr<JSC::CodeBlock>)
3   0x108878757 JSC::FunctionCodeBlock::FunctionCodeBlock(JSC::FunctionExecutable*, JSC::CodeType, JSC::JSGlobalObject*, WTF::PassRefPtr<JSC::SourceProvider>, unsigned int, bool, WTF::PassOwnPtr<JSC::CodeBlock>)
4   0x108875c5b JSC::FunctionExecutable::produceCodeBlockFor(JSC::ScopeChainNode*, JSC::CompilationKind, JSC::CodeSpecializationKind, JSC::JSObject*&)
5   0x108875689 JSC::FunctionExecutable::compileForCallInternal(JSC::ExecState*, JSC::ScopeChainNode*, JSC::JITCode::JITType)

[Simon Fraser (smfr)]

Actually RareCaseProfile, LLIntCallLinkInfo and ValueProfile still show up as having lots of wasted capacity.