Bug 207673 – [JSC] Compact JITCodeMap by storing BytecodeIndex and CodeLocation separately

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

[Yusuke Suzuki]

[JSC] Compact JITCodeMap by stroing BytecodeIndex and CodeLocation separately

[Yusuke Suzuki]

Created attachment 390603 [details]
Patch

[Mark Lam]

Comment on attachment 390603 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=390603&action=review

> Source/JavaScriptCore/ChangeLog:3
> +        [JSC] Compact JITCodeMap by stroing BytecodeIndex and CodeLocation separately

/stroing/strong/

[Yusuke Suzuki]

Created attachment 390605 [details]
Patch

[Yusuke Suzuki]

Comment on attachment 390603 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=390603&action=review

>> Source/JavaScriptCore/ChangeLog:3
>> +        [JSC] Compact JITCodeMap by stroing BytecodeIndex and CodeLocation separately
> 
> /stroing/strong/

Thanks, fixing.

[Yusuke Suzuki]

Created attachment 390606 [details]
Patch

[Mark Lam]

Comment on attachment 390606 [details]
Patch

r=me

[Yusuke Suzuki]

Committed r256498: <https://trac.webkit.org/changeset/256498>

[Radar WebKit Bug Importer]

<rdar://problem/59410018>

[Robin Morisset]

Comment on attachment 390606 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=390606&action=review

> Source/JavaScriptCore/jit/JITCodeMap.h:46
> +        m_pointer = MallocPtr<uint8_t>::malloc(sizeof(CodeLocationLabel<JSEntryPtrTag>) * m_size + sizeof(BytecodeIndex) * m_size);

Don't we need to insure some alignment minimum here ? (I would say alignof(CodeLocationLabel<JSEntryPtrTag>)

> Source/JavaScriptCore/jit/JITCodeMap.h:56
> +        return codeLocations()[index - indexes()];

I'm confused about this line. Can you explain why it is not just codeLocations()[index] ?

[Yusuke Suzuki]

Comment on attachment 390606 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=390606&action=review

>> Source/JavaScriptCore/jit/JITCodeMap.h:46
>> +        m_pointer = MallocPtr<uint8_t>::malloc(sizeof(CodeLocationLabel<JSEntryPtrTag>) * m_size + sizeof(BytecodeIndex) * m_size);
> 
> Don't we need to insure some alignment minimum here ? (I would say alignof(CodeLocationLabel<JSEntryPtrTag>)

MallocPtr is just calling malloc. So we can assume usual alignment requirement for malloc here.

>> Source/JavaScriptCore/jit/JITCodeMap.h:56
>> +        return codeLocations()[index - indexes()];
> 
> I'm confused about this line. Can you explain why it is not just codeLocations()[index] ?

index is `BytecodeIndex*` pointing the found entry (or nullptr). `index - indexes()` can calculate the offset.