Bug 154639

Summary: [ES6] Arrow function. Some not used byte code is emited
Product: WebKit Reporter: GSkachkov <gskachkov>
Component: JavaScriptCoreAssignee: Nobody <webkit-unassigned>
Status: RESOLVED FIXED    
Severity: Normal CC: commit-queue, keith_miller, mark.lam, msaboff, saam
Priority: P2    
Version: WebKit Nightly Build   
Hardware: Unspecified   
OS: Unspecified   
Bug Depends on:    
Bug Blocks: 140855    
Attachments:
Description Flags
Patch
none
Patch none

GSkachkov
Reported 2016-02-24 04:10:51 PST
During checking arrow function I found that some unused byte code is emited: for instance for: var f2 = function () { return ()=>'test';}; f2()(); was generated: .... f2#DrpDJu:[0x10de8f840->0x10de76f40, NoneFunctionCall, 20]: 20 m_instructions; 160 bytes; 1 parameter(s); 8 callee register(s); 7 variable(s) [ 0] enter [ 1] get_scope loc3 [ 3] mov loc4, loc3 [ 6] create_lexical_environment loc5, loc3, Cell: 0x10de3bdd0 (0x10de27600:[SymbolTable, {}, NonArray, Leaf]), ID: 20(const0), Undefined(const1) // Not used create_lexical_environment byte code [ 11] mov loc3, loc5 [ 14] op_new_arrow_func_exp loc7, loc3, f0 [ 18] ret loc7 Constants: k0 = Cell: 0x10de3bdd0 (0x10de27600:[SymbolTable, {}, NonArray, Leaf]), ID: 20 k1 = Undefined #An0cos:[0x10de8f620->0x10de76e00, NoneFunctionCall, 10]: 10 m_instructions; 80 bytes; 1 parameter(s); 8 callee register(s); 6 variable(s) [ 0] enter [ 1] get_scope loc3 [ 3] mov loc4, loc3 [ 6] ret String (atomic) (identifier): test, ID: 4(const1) [ 8] ret Undefined(const2) // Not used byte code
Attachments
Patch (7.90 KB, patch)
2016-03-01 00:19 PST, GSkachkov 		no flags
DetailsFormatted DiffDiff
Patch (9.41 KB, patch)
2016-03-01 11:36 PST, GSkachkov 		no flags
DetailsFormatted DiffDiff
Show Obsolete (1) View All Add attachment proposed patch, testcase, etc.
GSkachkov
Comment 1 2016-02-26 11:49:13 PST
Also TDZ is emited for 'this' in arrow function that is invoked in class method
GSkachkov
Comment 2 2016-03-01 00:19:18 PST
Created attachment 272552 [details] Patch Patch comming
GSkachkov
Comment 3 2016-03-01 09:17:25 PST
(In reply to comment #1) > Also TDZ is emited for 'this' in arrow function that is invoked in class > method I've checked and seems that this TDZ is not related to the arrow function. It always add when we're accessing to the 'superProperty'
GSkachkov
Comment 4 2016-03-01 11:36:25 PST
Created attachment 272579 [details] Patch Fix typo
Saam Barati
Comment 5 2016-03-01 12:03:17 PST
Comment on attachment 272579 [details] Patch View in context: https://bugs.webkit.org/attachment.cgi?id=272579&action=review > Source/JavaScriptCore/ChangeLog:13 > + 1.create_lexical_environment not emited always for arrow function, only if some of > + features(this/super/arguments/eval) is used inside of the arrow function. > + 2.load 'this' from arrow function scope in constructor is done only if super > + contains in arrow function Nice!
WebKit Commit Bot
Comment 6 2016-03-01 13:28:38 PST
Comment on attachment 272579 [details] Patch Clearing flags on attachment: 272579 Committed r197410: <http://trac.webkit.org/changeset/197410>
WebKit Commit Bot
Comment 7 2016-03-01 13:28:42 PST
All reviewed patches have been landed. Closing bug.
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