Changeset 47775 in webkit for trunk/JavaScriptCore/bytecompiler

Timestamp:

Aug 26, 2009, 12:46:47 AM (16 years ago)

Author:

[email protected]

Message:

How many copies of the parameters do you need?
​https://bugs.webkit.org/show_bug.cgi?id=28701

Reviewed by Darin Adler.

The function parameters in JSC get copied a lot - and unnecessarily so.

Originally this happened due to duplicating FunctionBodyNodes on recompilation,
though the problem has been exacerbated by copying the parameters from the
original function body onto the executable, then back onto the real body that
will be generated (this happens on every function). And this is all made worse
since the data structures in question are a little ugly - C style arrays of C++
objects containing ref counts, so they need a full copy-construct (rather than
a simple memcpy).

This can all be greatly simplified by just punting the parameters off into
their own ref-counted object, and forgoing all the copying.

~no performance change, possible slight progression.

• bytecompiler/BytecodeGenerator.cpp:

(JSC::BytecodeGenerator::BytecodeGenerator):

• bytecompiler/BytecodeGenerator.h:

(JSC::BytecodeGenerator::makeFunction):

• parser/Nodes.cpp:

(JSC::FunctionParameters::FunctionParameters):
(JSC::FunctionBodyNode::FunctionBodyNode):
(JSC::FunctionBodyNode::finishParsing):

• parser/Nodes.h:

(JSC::FunctionBodyNode::parameters):
(JSC::FunctionBodyNode::parameterCount):

• runtime/Executable.cpp:

(JSC::FunctionExecutable::~FunctionExecutable):
(JSC::FunctionExecutable::compile):
(JSC::FunctionExecutable::reparseExceptionInfo):
(JSC::FunctionExecutable::fromGlobalCode):
(JSC::FunctionExecutable::paramString):

• runtime/Executable.h:

(JSC::FunctionExecutable::FunctionExecutable):
(JSC::FunctionExecutable::parameterCount):

Location:

trunk/JavaScriptCore/bytecompiler

Files:

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

trunk/JavaScriptCore/bytecompiler/BytecodeGenerator.cpp

@@ -350 +350 @@
         addVar(*varStack[i].first, varStack[i].second & DeclarationStacks::IsConstant);
 
-    const Identifier* parameters = functionBody->parameters();
-    size_t parameterCount = functionBody->parameterCount();
+    FunctionParameters& parameters = *functionBody->parameters();
+    size_t parameterCount = parameters.size();
     m_nextParameterIndex = -RegisterFile::CallFrameHeaderSize - parameterCount - 1;
     m_parameters.grow(1 + parameterCount); // reserve space for "this"

trunk/JavaScriptCore/bytecompiler/BytecodeGenerator.h

@@ -420 +420 @@
         PassRefPtr<FunctionExecutable> makeFunction(FunctionBodyNode* body)
         {
-            return adoptRef(new FunctionExecutable(body->ident(), body->source(), body->usesArguments(), body->copyParameters(), body->parameterCount(), body->lineNo(), body->lastLine()));
+            return FunctionExecutable::create(body->ident(), body->source(), body->usesArguments(), body->parameters(), body->lineNo(), body->lastLine());
         }