Changeset 140947 in webkit for trunk/Source/JavaScriptCore/parser/Nodes.h

Timestamp:

Jan 27, 2013, 10:46:36 PM (12 years ago)

Author:

[email protected]

Message:

JSC: FunctionParameters are memory hungry.
<​http://webkit.org/b/108033>
<rdar://problem/13094803>

Reviewed by Sam Weinig.

Instead of inheriting from Vector<Identifier>, make FunctionParameters a simple fixed-size array
with a custom-allocating create() function. Removes one step of indirection and cuts memory usage
roughly in half.

2.73 MB progression on Membuster3.

• bytecode/UnlinkedCodeBlock.cpp:

(JSC::UnlinkedFunctionExecutable::paramString):

• bytecompiler/BytecodeGenerator.cpp:

(JSC::BytecodeGenerator::BytecodeGenerator):

• parser/Nodes.cpp:

(JSC::FunctionParameters::create):
(JSC::FunctionParameters::FunctionParameters):
(JSC::FunctionParameters::~FunctionParameters):

• parser/Nodes.h:

(FunctionParameters):
(JSC::FunctionParameters::size):
(JSC::FunctionParameters::at):
(JSC::FunctionParameters::identifiers):

File:

• trunk/Source/JavaScriptCore/parser/Nodes.h (modified) (1 diff)

trunk/Source/JavaScriptCore/parser/Nodes.h

@@ -1394 +1394 @@
     };
 
-    class FunctionParameters : public Vector<Identifier>, public RefCounted<FunctionParameters> {
+    class FunctionParameters : public RefCounted<FunctionParameters> {
         WTF_MAKE_FAST_ALLOCATED;
     public:
-        static PassRefPtr<FunctionParameters> create(ParameterNode* firstParameter) { return adoptRef(new FunctionParameters(firstParameter)); }
-
-    private:
-        FunctionParameters(ParameterNode*);
+        static PassRefPtr<FunctionParameters> create(ParameterNode*);
+        ~FunctionParameters();
+
+        unsigned size() const { return m_size; }
+        const Identifier& at(unsigned index) const { ASSERT(index < m_size); return identifiers()[index]; }
+
+    private:
+        FunctionParameters(ParameterNode*, unsigned size);
+
+        Identifier* identifiers() { return reinterpret_cast<Identifier*>(&m_storage); }
+        const Identifier* identifiers() const { return reinterpret_cast<const Identifier*>(&m_storage); }
+
+        unsigned m_size;
+        void* m_storage;
     };