RESOLVED FIXED Bug 157775
[JSC] "return this" in a constructor does not need a branch on isObject(this) 
https://bugs.webkit.org/show_bug.cgi?id=157775
Summary [JSC] "return this" in a constructor does not need a branch on isObject(this)
Benjamin Poulain
Reported 2016-05-16 17:25:47 PDT
[JSC] "return this" in a constructor does not need a branch on isObject(this)
Attachments
Patch (2.85 KB, patch)
2016-05-16 17:29 PDT, Benjamin Poulain 		no flags
DetailsFormatted DiffDiff
Patch (3.27 KB, patch)
2016-05-16 20:00 PDT, Benjamin Poulain 		no flags
DetailsFormatted DiffDiff
Patch for landing (3.28 KB, patch)
2016-05-16 20:06 PDT, Benjamin Poulain 		no flags
DetailsFormatted DiffDiff
Show Obsolete (2) View All Add attachment proposed patch, testcase, etc.
Benjamin Poulain
Comment 1 2016-05-16 17:29:39 PDT
Created attachment 279073 [details] Patch
Benjamin Poulain
Comment 2 2016-05-16 17:30:06 PDT
Conf#1 Conf#2 3d-cube 4.9549+-0.0261 ? 4.9916+-0.0312 ? 3d-morph 5.0523+-0.0255 ? 5.0780+-0.0304 ? 3d-raytrace 5.3399+-0.0310 5.3223+-0.0249 access-binary-trees 2.0966+-0.0164 ^ 2.0264+-0.0164 ^ definitely 1.0346x faster access-fannkuch 5.8749+-0.0359 ^ 5.8014+-0.0308 ^ definitely 1.0127x faster access-nbody 2.5241+-0.0162 ? 2.5462+-0.0184 ? access-nsieve 2.9690+-0.0152 2.9677+-0.0163 bitops-3bit-bits-in-byte 1.0807+-0.0084 ? 1.0826+-0.0085 ? bitops-bits-in-byte 2.7130+-0.0180 ? 2.7253+-0.0201 ? bitops-bitwise-and 2.0030+-0.0133 1.9902+-0.0108 bitops-nsieve-bits 3.0466+-0.0198 ? 3.0540+-0.0238 ? controlflow-recursive 2.3161+-0.0152 ? 2.3349+-0.0179 ? crypto-aes 4.4217+-0.0372 4.4038+-0.0318 crypto-md5 2.4412+-0.0167 2.4099+-0.0157 might be 1.0130x faster crypto-sha1 2.2903+-0.0174 ? 2.2995+-0.0180 ? date-format-tofte 6.6671+-0.0416 6.6478+-0.0401 date-format-xparb 4.8312+-0.0372 4.8075+-0.0361 math-cordic 2.8409+-0.0129 ? 2.8411+-0.0168 ? math-partial-sums 4.2179+-0.0366 4.2139+-0.0341 math-spectral-norm 1.9951+-0.0155 1.9880+-0.0119 regexp-dna 6.5850+-0.0456 ? 6.6112+-0.0548 ? string-base64 4.2546+-0.0384 4.2394+-0.0342 string-fasta 5.6429+-0.0195 5.6271+-0.0216 string-tagcloud 8.6104+-0.0471 ? 8.6181+-0.0574 ? string-unpack-code 18.7322+-0.1295 18.5419+-0.1163 might be 1.0103x faster string-validate-input 4.1828+-0.0290 ? 4.1885+-0.0282 ? <arithmetic> 4.5263+-0.0071 4.5138+-0.0073 might be 1.0028x faster
Saam Barati
Comment 3 2016-05-16 19:33:52 PDT
Comment on attachment 279073 [details] Patch View in context: https://bugs.webkit.org/attachment.cgi?id=279073&action=review > Source/JavaScriptCore/bytecompiler/BytecodeGenerator.cpp:3223 > + bool shouldEmitIsObjectTest = derived || !srcIsThis; I think that if you're in an ES6 derived constructor, your 'this' value must either be TDZ or an object. I'm fairly sure then that 'shouldEmitIsObjectTest' can just be !srcIsThis because the TDZ check above will cover 'this' being TDZ.
Benjamin Poulain
Comment 4 2016-05-16 20:00:08 PDT
Created attachment 279085 [details] Patch
Saam Barati
Comment 5 2016-05-16 20:01:10 PDT
Comment on attachment 279085 [details] Patch View in context: https://bugs.webkit.org/attachment.cgi?id=279085&action=review > Source/JavaScriptCore/bytecompiler/BytecodeGenerator.cpp:3232 > emitTDZCheck(&m_thisRegister); This can be: if (!srcIsThis) emitTDZCheck...
Saam Barati
Comment 6 2016-05-16 20:01:55 PDT
Comment on attachment 279085 [details] Patch View in context: https://bugs.webkit.org/attachment.cgi?id=279085&action=review >> Source/JavaScriptCore/bytecompiler/BytecodeGenerator.cpp:3232 >> emitTDZCheck(&m_thisRegister); > > This can be: > if (!srcIsThis) > emitTDZCheck... Oh. Never mind
Benjamin Poulain
Comment 7 2016-05-16 20:06:44 PDT
Created attachment 279087 [details] Patch for landing
WebKit Commit Bot
Comment 8 2016-05-16 20:35:48 PDT
Comment on attachment 279087 [details] Patch for landing Clearing flags on attachment: 279087 Committed r200992: <http://trac.webkit.org/changeset/200992>
WebKit Commit Bot
Comment 9 2016-05-16 20:35:53 PDT
All reviewed patches have been landed. Closing bug.
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