Changeset 174478 in webkit for trunk/Source/JavaScriptCore/bytecompiler

Timestamp:

Oct 8, 2014, 1:54:24 PM (11 years ago)

Author:

[email protected]

Message:

Make sure arguments tearoff is performed through the environment record if necessary
​https://bugs.webkit.org/show_bug.cgi?id=137538

Reviewed by Michael Saboff.

Fairly simple change. If we have a lexical record we need to pull the unmodified
arguments object from the record and then use the standard op_tear_off_arguments
instruction on the temporary.

• bytecompiler/BytecodeGenerator.cpp:

(JSC::BytecodeGenerator::emitGetOwnScope):
(JSC::BytecodeGenerator::emitReturn):

• bytecompiler/BytecodeGenerator.h:

Location:

trunk/Source/JavaScriptCore/bytecompiler

Files:

• BytecodeGenerator.cpp (modified) (2 diffs)
• BytecodeGenerator.h (modified) (1 diff)

trunk/Source/JavaScriptCore/bytecompiler/BytecodeGenerator.cpp

@@ -1300 +1300 @@
 }
 
+
+RegisterID* BytecodeGenerator::emitGetOwnScope(RegisterID* dst, const Identifier& identifier, OwnScopeLookupRules)
+{
+    emitOpcode(op_resolve_scope);
+    instructions().append(kill(dst));
+    instructions().append(addConstant(identifier));
+    instructions().append(LocalClosureVar);
+    // This should be m_localScopeDepth if we aren't doing
+    // resolution during emitReturn()
+    instructions().append(0);
+    instructions().append(0);
+    return dst;
+}
+
 RegisterID* BytecodeGenerator::emitResolveConstantLocal(RegisterID* dst, const Identifier& identifier, ResolveScopeInfo& info)
 {
@@ -1907 +1921 @@
 {
     if (m_codeBlock->usesArguments() && m_codeBlock->numParameters() != 1 && !isStrictMode()) {
+        RefPtr<RegisterID> scratchRegister;
+        int argumentsIndex = unmodifiedArgumentsRegister(m_codeBlock->argumentsRegister()).offset();
+        if (m_lexicalEnvironmentRegister && m_codeType == FunctionCode) {
+            scratchRegister = newTemporary();
+            emitGetOwnScope(scratchRegister.get(), propertyNames().arguments, OwnScopeForReturn);
+            ResolveScopeInfo scopeInfo(unmodifiedArgumentsRegister(m_codeBlock->argumentsRegister()).offset());
+            emitGetFromScope(scratchRegister.get(), scratchRegister.get(), propertyNames().arguments, ThrowIfNotFound, scopeInfo);
+            argumentsIndex = scratchRegister->index();
+        }
         emitOpcode(op_tear_off_arguments);
-        instructions().append(unmodifiedArgumentsRegister(m_codeBlock->argumentsRegister()).offset());
+        instructions().append(argumentsIndex);
         instructions().append(m_lexicalEnvironmentRegister ? m_lexicalEnvironmentRegister->index() : emitLoad(0, JSValue())->index());
     }

trunk/Source/JavaScriptCore/bytecompiler/BytecodeGenerator.h

@@ -660 +660 @@
         RegisterID* initializeCapturedVariable(RegisterID* dst, const Identifier&, RegisterID*);
 
+        // We'll may want a non-return mode in future, but currently
+        // this is only used during emitReturn(). emitReturn() occurs
+        // with the novel state of having popped off all the local scope
+        // nodes, but not actually modify any internal stack depth tracking.
+        enum OwnScopeLookupRules { OwnScopeForReturn };
+        RegisterID* emitGetOwnScope(RegisterID* dst, const Identifier&, OwnScopeLookupRules);
+
     public:
         JSString* addStringConstant(const Identifier&);