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<dt>Revision</dt> <dd><a href="http://trac.webkit.org/projects/webkit/changeset/206082">206082</a></dd>
<dt>Author</dt> <dd>utatane.tea@gmail.com</dd>
<dt>Date</dt> <dd>2016-09-18 10:40:11 -0700 (Sun, 18 Sep 2016)</dd>
</dl>
<h3>Log Message</h3>
<pre>[JSC] Do not need to use defineProperty to define methods for object literals
https://bugs.webkit.org/show_bug.cgi?id=162111
Reviewed by Saam Barati.
JSTests:
* stress/object-literal-methods.js: Added.
(shouldBe):
(throw.new.Error.let.object.get name):
(throw.new.Error):
(shouldBe.let.object.get name):
(shouldBe.let.object.get prototype):
(shouldBe.let.object.get 42):
Source/JavaScriptCore:
When we receive the following code,
var object = { method() { } };
currently, we use defineProperty to define "method" function for "object".
This patch replaces it with the ordinary put_by_id_direct / put_by_val_direct
because the following 2 conditions are met.
1. While methods in classes have special attributes ({configurable: true, writable: true, enumerable: false}),
the attributes of methods in object literals is just the same to the other normal properties ({configurable: true, writable: true, enumerable: true}).
This means that we can use the usual put_by_id_direct / put_by_val_direct to define method properties for object literals.
2. Furthermore, all the own properties that can reside in objects created by object literals have {configurable: true}.
So there is no need to check conflict by defineProperty. Always overwriting is OK.
let name = 'method';
var object = { get [name]() { }, method() { } };
// Latter method wins.
On the other hand, in class syntax, conflict check is necessary since "prototype" own property is defined as {configurable: false}.
class Hello { static prototype() { } } // Should throw error by defineProperty's check.
This means that conflict check done in defneProperty is not necessary for object literals' properties.
* bytecompiler/NodesCodegen.cpp:
(JSC::PropertyListNode::emitPutConstantProperty):</pre>
<h3>Modified Paths</h3>
<ul>
<li><a href="#trunkJSTestsChangeLog">trunk/JSTests/ChangeLog</a></li>
<li><a href="#trunkSourceJavaScriptCoreChangeLog">trunk/Source/JavaScriptCore/ChangeLog</a></li>
<li><a href="#trunkSourceJavaScriptCorebytecompilerNodesCodegencpp">trunk/Source/JavaScriptCore/bytecompiler/NodesCodegen.cpp</a></li>
</ul>
<h3>Added Paths</h3>
<ul>
<li><a href="#trunkJSTestsstressobjectliteralmethodsjs">trunk/JSTests/stress/object-literal-methods.js</a></li>
</ul>
</div>
<div id="patch">
<h3>Diff</h3>
<a id="trunkJSTestsChangeLog"></a>
<div class="modfile"><h4>Modified: trunk/JSTests/ChangeLog (206081 => 206082)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/JSTests/ChangeLog 2016-09-18 17:36:31 UTC (rev 206081)
+++ trunk/JSTests/ChangeLog 2016-09-18 17:40:11 UTC (rev 206082)
</span><span class="lines">@@ -1,3 +1,18 @@
</span><ins>+2016-09-18 Yusuke Suzuki <utatane.tea@gmail.com>
+
+ [JSC] Do not need to use defineProperty to define methods for object literals
+ https://bugs.webkit.org/show_bug.cgi?id=162111
+
+ Reviewed by Saam Barati.
+
+ * stress/object-literal-methods.js: Added.
+ (shouldBe):
+ (throw.new.Error.let.object.get name):
+ (throw.new.Error):
+ (shouldBe.let.object.get name):
+ (shouldBe.let.object.get prototype):
+ (shouldBe.let.object.get 42):
+
</ins><span class="cx"> 2016-09-16 Yusuke Suzuki <utatane.tea@gmail.com>
</span><span class="cx">
</span><span class="cx"> [DFG] Introduce IsCellWithType node and unify IsJSArray, IsRegExpObject and newly added IsProxyObject
</span></span></pre></div>
<a id="trunkJSTestsstressobjectliteralmethodsjs"></a>
<div class="addfile"><h4>Added: trunk/JSTests/stress/object-literal-methods.js (0 => 206082)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/JSTests/stress/object-literal-methods.js (rev 0)
+++ trunk/JSTests/stress/object-literal-methods.js 2016-09-18 17:40:11 UTC (rev 206082)
</span><span class="lines">@@ -0,0 +1,105 @@
</span><ins>+function shouldBe(actual, expected) {
+ if (actual !== expected)
+ throw new Error('bad value: ' + actual);
+}
+
+{
+ let name = 'prototype';
+ let object = {
+ prototype() { },
+ get [name]() { },
+ };
+
+ shouldBe(JSON.stringify(Object.getOwnPropertyDescriptor(object, 'prototype')), `{"enumerable":true,"configurable":true}`);
+}
+
+{
+ let name = 'prototype';
+ let object = {
+ get [name]() { },
+ prototype() { },
+ };
+
+ shouldBe(JSON.stringify(Object.getOwnPropertyDescriptor(object, 'prototype')), `{"writable":true,"enumerable":true,"configurable":true}`);
+}
+
+
+{
+ let name = 'prototype';
+ let object = {
+ [name]() { },
+ get prototype() { },
+ };
+
+ shouldBe(JSON.stringify(Object.getOwnPropertyDescriptor(object, 'prototype')), `{"enumerable":true,"configurable":true}`);
+}
+
+{
+ let name = 'prototype';
+ let object = {
+ get prototype() { },
+ [name]() { },
+ };
+
+ shouldBe(JSON.stringify(Object.getOwnPropertyDescriptor(object, 'prototype')), `{"writable":true,"enumerable":true,"configurable":true}`);
+}
+
+{
+ let object = {
+ __proto__() { }
+ };
+ shouldBe(JSON.stringify(Object.getOwnPropertyDescriptor(object, '__proto__')), `{"writable":true,"enumerable":true,"configurable":true}`);
+ shouldBe(Object.getPrototypeOf(object), Object.prototype);
+}
+
+{
+ let name = '__proto__';
+ let object = {
+ [name]() { }
+ };
+ shouldBe(JSON.stringify(Object.getOwnPropertyDescriptor(object, '__proto__')), `{"writable":true,"enumerable":true,"configurable":true}`);
+ shouldBe(Object.getPrototypeOf(object), Object.prototype);
+}
+
+{
+ let name = '42';
+ let object = {
+ 42() { },
+ get [name]() { },
+ };
+
+ shouldBe(JSON.stringify(Object.getOwnPropertyDescriptor(object, '42')), `{"enumerable":true,"configurable":true}`);
+}
+
+{
+ let name = '42';
+ let object = {
+ get [name]() { },
+ 42() { },
+ };
+
+ shouldBe(JSON.stringify(Object.getOwnPropertyDescriptor(object, '42')), `{"writable":true,"enumerable":true,"configurable":true}`);
+}
+
+
+{
+ let name = '42';
+ let object = {
+ [name]() { },
+ get 42() { },
+ };
+
+ shouldBe(JSON.stringify(Object.getOwnPropertyDescriptor(object, '42')), `{"enumerable":true,"configurable":true}`);
+}
+
+{
+ let name = '42';
+ let object = {
+ get 42() { },
+ [name]() { },
+ };
+
+ shouldBe(JSON.stringify(Object.getOwnPropertyDescriptor(object, '42')), `{"writable":true,"enumerable":true,"configurable":true}`);
+}
+
+
</ins></span></pre></div>
<a id="trunkSourceJavaScriptCoreChangeLog"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/ChangeLog (206081 => 206082)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/ChangeLog 2016-09-18 17:36:31 UTC (rev 206081)
+++ trunk/Source/JavaScriptCore/ChangeLog 2016-09-18 17:40:11 UTC (rev 206082)
</span><span class="lines">@@ -1,3 +1,38 @@
</span><ins>+2016-09-18 Yusuke Suzuki <utatane.tea@gmail.com>
+
+ [JSC] Do not need to use defineProperty to define methods for object literals
+ https://bugs.webkit.org/show_bug.cgi?id=162111
+
+ Reviewed by Saam Barati.
+
+ When we receive the following code,
+
+ var object = { method() { } };
+
+ currently, we use defineProperty to define "method" function for "object".
+ This patch replaces it with the ordinary put_by_id_direct / put_by_val_direct
+ because the following 2 conditions are met.
+
+ 1. While methods in classes have special attributes ({configurable: true, writable: true, enumerable: false}),
+ the attributes of methods in object literals is just the same to the other normal properties ({configurable: true, writable: true, enumerable: true}).
+ This means that we can use the usual put_by_id_direct / put_by_val_direct to define method properties for object literals.
+
+ 2. Furthermore, all the own properties that can reside in objects created by object literals have {configurable: true}.
+ So there is no need to check conflict by defineProperty. Always overwriting is OK.
+
+ let name = 'method';
+ var object = { get [name]() { }, method() { } };
+ // Latter method wins.
+
+ On the other hand, in class syntax, conflict check is necessary since "prototype" own property is defined as {configurable: false}.
+
+ class Hello { static prototype() { } } // Should throw error by defineProperty's check.
+
+ This means that conflict check done in defneProperty is not necessary for object literals' properties.
+
+ * bytecompiler/NodesCodegen.cpp:
+ (JSC::PropertyListNode::emitPutConstantProperty):
+
</ins><span class="cx"> 2016-09-16 Yusuke Suzuki <utatane.tea@gmail.com>
</span><span class="cx">
</span><span class="cx"> [DFG] Introduce IsCellWithType node and unify IsJSArray, IsRegExpObject and newly added IsProxyObject
</span></span></pre></div>
<a id="trunkSourceJavaScriptCorebytecompilerNodesCodegencpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/bytecompiler/NodesCodegen.cpp (206081 => 206082)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/bytecompiler/NodesCodegen.cpp 2016-09-18 17:36:31 UTC (rev 206081)
+++ trunk/Source/JavaScriptCore/bytecompiler/NodesCodegen.cpp 2016-09-18 17:40:11 UTC (rev 206082)
</span><span class="lines">@@ -587,9 +587,11 @@
</span><span class="cx"> void PropertyListNode::emitPutConstantProperty(BytecodeGenerator& generator, RegisterID* newObj, PropertyNode& node)
</span><span class="cx"> {
</span><span class="cx"> RefPtr<RegisterID> value = generator.emitNode(node.m_assign);
</span><del>- if (node.needsSuperBinding()) {
</del><ins>+ if (node.needsSuperBinding())
</ins><span class="cx"> emitPutHomeObject(generator, value.get(), newObj);
</span><span class="cx">
</span><ins>+ if (node.isClassProperty()) {
+ ASSERT(node.needsSuperBinding());
</ins><span class="cx"> RefPtr<RegisterID> propertyNameRegister;
</span><span class="cx"> if (node.name())
</span><span class="cx"> propertyNameRegister = generator.emitLoad(generator.newTemporary(), *node.name());
</span><span class="lines">@@ -596,12 +598,8 @@
</span><span class="cx"> else
</span><span class="cx"> propertyNameRegister = generator.emitNode(node.m_expression);
</span><span class="cx">
</span><del>- unsigned attributes = BytecodeGenerator::PropertyConfigurable | BytecodeGenerator::PropertyWritable;
- if (!node.isClassProperty())
- attributes |= BytecodeGenerator::PropertyEnumerable;
</del><span class="cx"> generator.emitSetFunctionNameIfNeeded(node.m_assign, value.get(), propertyNameRegister.get());
</span><del>- generator.emitCallDefineProperty(newObj, propertyNameRegister.get(),
- value.get(), nullptr, nullptr, attributes, m_position);
</del><ins>+ generator.emitCallDefineProperty(newObj, propertyNameRegister.get(), value.get(), nullptr, nullptr, BytecodeGenerator::PropertyConfigurable | BytecodeGenerator::PropertyWritable, m_position);
</ins><span class="cx"> return;
</span><span class="cx"> }
</span><span class="cx"> if (const auto* identifier = node.name()) {
</span></span></pre>
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