Bug 204536 – Use LLInt profiling to rule out generating an IC for get_by_val

• Status: RESOLVED
• Resolution: FIXED
• Component: JavaScriptCore

[Saam Barati]

...

[Saam Barati]

Created attachment 384216 [details]
patch

[Yusuke Suzuki]

Comment on attachment 384216 [details]
patch

View in context: https://bugs.webkit.org/attachment.cgi?id=384216&action=review

r=me

> Source/JavaScriptCore/bytecode/BytecodeList.rb:537
> +        seenIdentifiers: uint64_t, # Top 8 bits are the seen identifier count. Lower 56 bits are a bloom filter of seen UniquedStringImpl*.

I recommend introducing a class like GetByValHistory etc. not to use uint64_t directly.

> Source/JavaScriptCore/jit/JITPropertyAccess.cpp:97
> +    if (m_fastGetByVals.contains(currentInstruction)) {

You can count # of slowcase jumps by using `iter` (see JIT::linkAllSlowCasesForBytecodeIndex code, which iterates all slowcase jumps), and we can omit this code generation when slowcase count is 0, instead of tracking it by m_fastGetByVals.

[Saam Barati]

Created attachment 384221 [details]
patch for landing

[Saam Barati]

Comment on attachment 384216 [details]
patch

View in context: https://bugs.webkit.org/attachment.cgi?id=384216&action=review

>> Source/JavaScriptCore/bytecode/BytecodeList.rb:537
>> +        seenIdentifiers: uint64_t, # Top 8 bits are the seen identifier count. Lower 56 bits are a bloom filter of seen UniquedStringImpl*.
> 
> I recommend introducing a class like GetByValHistory etc. not to use uint64_t directly.

nice. Done

>> Source/JavaScriptCore/jit/JITPropertyAccess.cpp:97
>> +    if (m_fastGetByVals.contains(currentInstruction)) {
> 
> You can count # of slowcase jumps by using `iter` (see JIT::linkAllSlowCasesForBytecodeIndex code, which iterates all slowcase jumps), and we can omit this code generation when slowcase count is 0, instead of tracking it by m_fastGetByVals.

nice. Done

[WebKit Commit Bot]

Comment on attachment 384221 [details]
patch for landing

Clearing flags on attachment: 384221

Committed r252825: <https://trac.webkit.org/changeset/252825>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.

[Radar WebKit Bug Importer]

<rdar://problem/57448652>

[Saam Barati]

32-bit build fix in:
https://trac.webkit.org/changeset/252871/webkit