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

Timestamp:

Jan 27, 2013, 10:46:36 PM (13 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.cpp (modified) (2 diffs)

trunk/Source/JavaScriptCore/parser/Nodes.cpp

@@ -152 +152 @@
 // ------------------------------ FunctionBodyNode -----------------------------
 
-FunctionParameters::FunctionParameters(ParameterNode* firstParameter)
+PassRefPtr<FunctionParameters> FunctionParameters::create(ParameterNode* firstParameter)
 {
     unsigned parameterCount = 0;
@@ -158 +158 @@
         ++parameterCount;
 
-    reserveInitialCapacity(parameterCount);
-
+    size_t objectSize = sizeof(FunctionParameters) - sizeof(void*) + sizeof(StringImpl*) * parameterCount;
+    void* slot = fastMalloc(objectSize);
+    return adoptRef(new (slot) FunctionParameters(firstParameter, parameterCount));
+}
+
+FunctionParameters::FunctionParameters(ParameterNode* firstParameter, unsigned size)
+    : m_size(size)
+{
+    unsigned i = 0;
     for (ParameterNode* parameter = firstParameter; parameter; parameter = parameter->nextParam())
-        uncheckedAppend(parameter->ident());
+        new (&identifiers()[i++]) Identifier(parameter->ident());
+}
+
+FunctionParameters::~FunctionParameters()
+{
+    for (unsigned i = 0; i < m_size; ++i)
+        identifiers()[i].~Identifier();
 }