chakra-core/ChakraCore

Optimize OP_LdCustomSpreadIteratorList for arguments object

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#1,230 建立於 2016年7月1日

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 (10 留言) (0 反應) (0 負責人)JavaScript (9,000 star) (1,374 fork)batch import
PerformanceProposalSuggestiongood first issuehelp wanted

描述

I was looking into the code of OP_LdCustomSpreadIteratorList and noticed that we optimize it by not creating SpreadArgument if parameter passed to OP_LdCustomSpreadIteratorList does not have user defined iterator. We do this check only for JavascriptArray and TypedArrayBase and we can expand it for ArgumentsObject as well. As per spec, both unmapped and mapped argument objects has default @@iterator set to Array.proto.values.

貢獻者指南

技術棧
cppjavascript
領域
performance
議題類型
performance
難度面向新貢獻者的預計實作難度，1 表示很小改動，5 表示專家級工作。
5
預計時間有經驗貢獻者完成調查、實作、測試並準備 pull request 的粗略時間範圍。
3-5 days
活動狀態議題目前的可參與程度：新鮮、活躍、陳舊、阻塞或等待維護者輸入。
stale
清晰度議題是否清楚說明預期改動、驗收標準和下一步。
clear
前置要求
C++ proficiencyUnderstanding of JavaScript iteratorsChakraCore codebase familiarityBasic knowledge of ES6 spread operator
新手友善度1-100 的估計分數，表示該議題對首次貢獻者的友善程度。
10
研究方向
Examine the existing optimization in lib/Runtime/Language/JavascriptOperators.cpp at line 1405. Understand how the check for non user defined iterator is done for JavascriptArray and TypedArrayBase. Then extend the same logic to ArgumentsObject, ensuring that the arguments object's default iterator (Array.prototype.values) is used. Consider edge cases where the arguments object might have its @@iterator overridden. Write tests to cover the optimization.