Changeset 269801 in webkit for trunk/Source/JavaScriptCore/bytecompiler/NodesCodegen.cpp

Timestamp:

Nov 13, 2020, 2:32:01 PM (5 years ago)

Author:

[email protected]

Message:

[JSC] Use symbols as identifiers for class fields computed names storage
​https://bugs.webkit.org/show_bug.cgi?id=216172

Patch by Xan López <Xan Lopez> on 2020-11-13
Reviewed by Yusuke Suzuki.

Use private symbols for the property keys of the class fields with
computed names. This is cleaner than using raw numeric identifiers and
will be less cumbersome when we add static fields. It also prevents
potential collisions if other features want to store data in the class
scope.

JSTests:

• stress/class-fields-harmony.js: new test, make sure

setFunctionName works properly with computed fields.

Source/JavaScriptCore:

• bytecompiler/NodesCodegen.cpp:

(JSC::PropertyListNode::emitSaveComputedFieldName): adapt a comment.

• parser/Parser.cpp:

(JSC::Parser<LexerType>::parseClass): use private identifiers for computed fields property keys.
(JSC::Parser<LexerType>::parseInstanceFieldInitializerSourceElements): ditto.

• parser/ParserArena.cpp:

(JSC::IdentifierArena::makePrivateIdentifier): method to create a private identifier.

• parser/ParserArena.h:
• runtime/CachedTypes.cpp:

(JSC::CachedUniquedStringImplBase::encode): consider registered symbols, they are used by the parser now.
(JSC::CachedUniquedStringImplBase::decode const): ditto.

• runtime/VM.cpp:

(JSC::VM::VM):

• runtime/VM.h:

(JSC::VM::privateSymbolRegistry): create a private symbol registry too.

Source/WTF:

• wtf/text/SymbolImpl.cpp:

(WTF::RegisteredSymbolImpl::createPrivate): add a method to create a registered private symbol from a string key.

• wtf/text/SymbolImpl.h:
• wtf/text/SymbolRegistry.cpp:

(WTF::SymbolRegistry::symbolForKey): consider that we can hold private symbols now too.

• wtf/text/SymbolRegistry.h:

(WTF::SymbolRegistry::SymbolRegistry): new enum type for public/private symbols.

File:

• trunk/Source/JavaScriptCore/bytecompiler/NodesCodegen.cpp (modified) (5 diffs)

trunk/Source/JavaScriptCore/bytecompiler/NodesCodegen.cpp

@@ -803 +803 @@
     RefPtr<RegisterID> propertyExpr;
 
-    // The 'name' refers to a synthetic numeric variable name in the private name scope, where the property key is saved for later use.
+    // The 'name' refers to a synthetic private name in the class scope, where the property key is saved for later use.
     const Identifier& description = *node.name();
     Variable var = generator.variable(description);
@@ -4818 +4818 @@
 {
     RefPtr<RegisterID> value = generator.newTemporary();
+    bool shouldSetFunctionName = false;
 
     if (!m_assign)
@@ -4823 +4824 @@
     else {
         generator.emitNode(value.get(), m_assign);
-        if (m_ident && generator.shouldSetFunctionName(m_assign))
+        shouldSetFunctionName = generator.shouldSetFunctionName(m_assign);
+        if (m_ident && shouldSetFunctionName && m_type != DefineFieldNode::Type::ComputedName)
             generator.emitSetFunctionName(value.get(), *m_ident);
     }
@@ -4851 +4853 @@
 
         // For ComputedNames, the expression has already been evaluated earlier during evaluation of a ClassExprNode.
-        // Here, `m_ident` refers to an integer ID in a class lexical scope, containing the value already converted to an Expression.
+        // Here, `m_ident` refers to private symbol ID in a class lexical scope, containing the value already converted to an Expression.
         Variable var = generator.variable(*m_ident);
         ASSERT_WITH_MESSAGE(!var.local(), "Computed names must be stored in captured variables");
@@ -4859 +4861 @@
         RefPtr<RegisterID> privateName = generator.newTemporary();
         generator.emitGetFromScope(privateName.get(), scope.get(), var, ThrowIfNotFound);
+        if (shouldSetFunctionName)
+            generator.emitSetFunctionName(value.get(), privateName.get());
         generator.emitProfileType(privateName.get(), var, m_position, m_position + m_ident->length());
         generator.emitCallDefineProperty(generator.thisRegister(), privateName.get(), value.get(), nullptr, nullptr, BytecodeGenerator::PropertyConfigurable | BytecodeGenerator::PropertyWritable | BytecodeGenerator::PropertyEnumerable, m_position);