Branch: refs/heads/main
Home: https://github.com/WebKit/WebKit
Commit: 8f5016427be1a14414038b83395a443c94c10084
https://github.com/WebKit/WebKit/commit/8f5016427be1a14414038b83395a443c94c10084
Author: Yusuke Suzuki <[email protected]>
Date: 2023-04-26 (Wed, 26 Apr 2023)
Changed paths:
A JSTests/microbenchmarks/object-assign-empty.js
M Source/JavaScriptCore/dfg/DFGOperations.cpp
M Source/JavaScriptCore/dfg/DFGSpeculativeJIT.cpp
M Source/JavaScriptCore/ftl/FTLAbstractHeapRepository.h
M Source/JavaScriptCore/ftl/FTLLowerDFGToB3.cpp
M Source/JavaScriptCore/runtime/JSObject.cpp
M Source/JavaScriptCore/runtime/ObjectConstructor.cpp
M Source/JavaScriptCore/runtime/ObjectConstructorInlines.h
M Source/JavaScriptCore/runtime/Structure.h
M Source/JavaScriptCore/runtime/StructureInlines.h
M Source/JavaScriptCore/runtime/StructureRareData.h
Log Message:
-----------
[JSC] Optimize Object.assign with empty object
https://bugs.webkit.org/show_bug.cgi?id=256019
rdar://108585195
Reviewed by Alexey Shvayka.
Actually, this is pretty common that Object.assign's source objects are empty.
The reason is the pattern like this,
function func(options = {}) {
var options = Object.assign({ defaultOption1: true, defaultOption2:
false }, options);
...
}
And if we call this func with no-options, then Object.assign will see empty
options object.
This patch adds a fast path for that in C++ and DFG / FTL JIT.
1. In DFG and FTL, we quickly check empty objects and skip the execution of
Object.assign if source is empty.
2. In C++, we check property count before entering into
putOwnDataPropertyBatching.
3. We also relax putOwnDataPropertyBatching. Transition possibility should be
checked only when we cause the transition.
Otherwise, we do not need to give up the optimization, like, just replacing
properties.
ToT Patched
object-assign-transition 84.0831+-0.2116 ^ 70.7839+-0.2697
^ definitely 1.1879x faster
object-assign-replace 77.5201+-0.2244 ^ 72.5579+-0.1398
^ definitely 1.0684x faster
object-assign-empty 13.7165+-0.0783 ^ 7.0465+-0.0528
^ definitely 1.9466x faster
object-assign-multiple 132.1961+-0.1656 ^ 98.9260+-0.5316
^ definitely 1.3363x faster
* JSTests/microbenchmarks/object-assign-empty.js: Added.
(test):
* Source/JavaScriptCore/dfg/DFGOperations.cpp:
(JSC::DFG::JSC_DEFINE_JIT_OPERATION):
* Source/JavaScriptCore/dfg/DFGSpeculativeJIT.cpp:
* Source/JavaScriptCore/ftl/FTLAbstractHeapRepository.h:
* Source/JavaScriptCore/ftl/FTLLowerDFGToB3.cpp:
(JSC::FTL::DFG::LowerDFGToB3::compileObjectAssign):
* Source/JavaScriptCore/runtime/JSObject.cpp:
(JSC::JSObject::putOwnDataPropertyBatching):
* Source/JavaScriptCore/runtime/ObjectConstructor.cpp:
(JSC::JSC_DEFINE_HOST_FUNCTION):
* Source/JavaScriptCore/runtime/ObjectConstructorInlines.h:
(JSC::objectAssignFast):
* Source/JavaScriptCore/runtime/Structure.h:
(JSC::Structure::propertyHashOffset):
* Source/JavaScriptCore/runtime/StructureInlines.h:
(JSC::Structure::canPerformFastPropertyEnumeration const):
* Source/JavaScriptCore/runtime/StructureRareData.h:
Canonical link: https://commits.webkit.org/263444@main
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