2010-09-25 Oliver Hunt <oliver@apple.com>
Reviewed by Cameron Zwarich.
Avoid constructing arguments object when accessing length and index properties
https://bugs.webkit.org/show_bug.cgi?id=46572
Add opcodes to read argument length and properties, and then implement them.
Much like other lazy opcodes these opcodes take a fast path when the arguments
object has not been instantiated, and fall back on generic access mechanisms
if they are acting on an instantiated object.
3% win on v8-earleyboyer, no change elsewhere.
* bytecode/CodeBlock.cpp:
(JSC::CodeBlock::dump):
* bytecode/Opcode.h:
* bytecompiler/BytecodeGenerator.cpp:
(JSC::BytecodeGenerator::emitGetArgumentsLength):
(JSC::BytecodeGenerator::emitGetArgumentByVal):
* bytecompiler/BytecodeGenerator.h:
* bytecompiler/NodesCodegen.cpp:
(JSC::BracketAccessorNode::emitBytecode):
(JSC::DotAccessorNode::emitBytecode):
* interpreter/Interpreter.cpp:
(JSC::Interpreter::privateExecute):
* jit/JIT.cpp:
(JSC::JIT::privateCompileMainPass):
(JSC::JIT::privateCompileSlowCases):
* jit/JIT.h:
* jit/JITOpcodes.cpp:
(JSC::JIT::emit_op_get_arguments_length):
(JSC::JIT::emitSlow_op_get_arguments_length):
(JSC::JIT::emit_op_get_argument_by_val):
(JSC::JIT::emitSlow_op_get_argument_by_val):
* jit/JITOpcodes32_64.cpp:
(JSC::JIT::emit_op_get_arguments_length):
(JSC::JIT::emitSlow_op_get_arguments_length):
(JSC::JIT::emit_op_get_argument_by_val):
(JSC::JIT::emitSlow_op_get_argument_by_val):
git-svn-id: http://svn.webkit.org/repository/webkit/trunk@68338 268f45cc-cd09-0410-ab3c-d52691b4dbfc
diff --git a/JavaScriptCore/bytecompiler/NodesCodegen.cpp b/JavaScriptCore/bytecompiler/NodesCodegen.cpp
index f098ba6..2cc1a3f 100644
--- a/JavaScriptCore/bytecompiler/NodesCodegen.cpp
+++ b/JavaScriptCore/bytecompiler/NodesCodegen.cpp
@@ -290,6 +290,12 @@
RegisterID* BracketAccessorNode::emitBytecode(BytecodeGenerator& generator, RegisterID* dst)
{
+ if (m_base->isResolveNode() && generator.willResolveToArguments(static_cast<ResolveNode*>(m_base)->identifier())) {
+ RegisterID* property = generator.emitNode(m_subscript);
+ generator.emitExpressionInfo(divot(), startOffset(), endOffset());
+ return generator.emitGetArgumentByVal(generator.finalDestination(dst), generator.uncheckedRegisterForArguments(), property);
+ }
+
RefPtr<RegisterID> base = generator.emitNodeForLeftHandSide(m_base, m_subscriptHasAssignments, m_subscript->isPure(generator));
RegisterID* property = generator.emitNode(m_subscript);
generator.emitExpressionInfo(divot(), startOffset(), endOffset());
@@ -300,6 +306,17 @@
RegisterID* DotAccessorNode::emitBytecode(BytecodeGenerator& generator, RegisterID* dst)
{
+ if (m_ident == generator.propertyNames().length) {
+ if (!m_base->isResolveNode())
+ goto nonArgumentsPath;
+ ResolveNode* resolveNode = static_cast<ResolveNode*>(m_base);
+ if (!generator.willResolveToArguments(resolveNode->identifier()))
+ goto nonArgumentsPath;
+ generator.emitExpressionInfo(divot(), startOffset(), endOffset());
+ return generator.emitGetArgumentsLength(generator.finalDestination(dst), generator.uncheckedRegisterForArguments());
+ }
+
+nonArgumentsPath:
RegisterID* base = generator.emitNode(m_base);
generator.emitExpressionInfo(divot(), startOffset(), endOffset());
return generator.emitGetById(generator.finalDestination(dst), base, m_ident);
