[webkit-changes] [WebKit/WebKit] cacf00: Add fast path of getting arguments.length for LLIn...

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  Branch: refs/heads/main
  Home:   https://github.com/WebKit/WebKit
  Commit: cacf00c5fdeedd4db49495feaa674396691def67
      https://github.com/WebKit/WebKit/commit/cacf00c5fdeedd4db49495feaa674396691def67
  Author: Yijia Huang <yijia_huang at apple.com>
  Date:   2023-09-26 (Tue, 26 Sep 2023)

  Changed paths:
    A JSTests/microbenchmarks/get-arguments-length-fast.js
    A JSTests/stress/get-arguments-length-fast.js
    M Source/JavaScriptCore/bytecompiler/BytecodeGenerator.cpp
    M Source/JavaScriptCore/bytecompiler/BytecodeGenerator.h
    M Source/JavaScriptCore/bytecompiler/NodesCodegen.cpp
    M Source/JavaScriptCore/parser/ASTBuilder.h
    M Source/JavaScriptCore/parser/Nodes.h
    M Source/JavaScriptCore/parser/Parser.cpp
    M Source/JavaScriptCore/parser/Parser.h
    M Source/JavaScriptCore/parser/SyntaxChecker.h

  Log Message:
  -----------
  Add fast path of getting arguments.length for LLInt and Baseline
https://bugs.webkit.org/show_bug.cgi?id=261543
rdar://115462355

Reviewed by Yusuke Suzuki.

We observed that `arguments.length` is frequently used for reading only
without accessing/modifying arguments self or its other properties. If that's
the case we should directly get `argumentCountIncludingThis` from CallFrame
without materializing `arguments` object first. So far, DFG and FTL can
handle this well in varargs forwarding phase. This patch adds the fast
path of getting arguments.length for LLInt and Baseline with simple
heuristic in parser layer.

JavaScriptCode:

    function test() {
        return arguments.length === 3;
    }

Bytecode Before:

    Predecessors: [ ]
    [   0] enter
    [   1] create_direct_arguments dst:loc5
    [   3] mov                dst:loc6, src:loc5
    [   6] get_by_id          dst:loc7, base:loc6, property:0, valueProfile:1
    [  12] stricteq           dst:loc7, lhs:loc7, rhs:Int32: 3(const0)
    [  16] ret                value:loc7
    Successors: [ ]

Bytecode After:

    Predecessors: [ ]
    [   0] enter
    [   1] argument_count     dst:loc5
    [   3] stricteq           dst:loc5, lhs:loc5, rhs:Int32: 3(const0)
    [   7] ret                value:loc5
    Successors: [ ]

Micro Benchmark Result:

                                without                     with

get-arguments-length-fast    2.6024+-0.0750     ^      2.4034+-0.0359        ^ definitely 1.0828x faster

* JSTests/microbenchmarks/get-arguments-length-fast.js: Added.
(test):
* JSTests/stress/get-arguments-length-fast.js: Added.
(shouldBe):
(argumentsWithNestedNormalFunction.nested):
(argumentsWithNestedNormalFunction):
(argumentsNonLengthAccess):
(argumentsLengthAssignment):
(argumentsAssignmentLHS):
(argumentsAssignmentRHS):
(argumentsDestructuringAssignment):
(declareVarArguments):
(declareVarArgumentsWithBlock):
(declareLexicalArguments):
(declareLexicalArgumentsWithBlock):
(declareArrowFunctionArguments):
(declareArrowFunctionArgumentsWithBlock):
(declareFunctionArguments.arguments):
(declareFunctionArguments):
(declareFunctionArgumentsWithBlock.arguments):
(declareFunctionArgumentsWithBlock):
(declareParameterArguments):
(returnArguments):
(helper):
(passArgumentsToFunctionCall):
(ifArguments):
(forInArguments):
(forInVarArguments):
(forInLetArguments):
(forOfArguments):
(forOfVarArguments):
(forOfLetArguments):
(withArguments):
(argumentsWithNestedFunctions.nestedNormalFunction):
(argumentsWithNestedFunctions):
* Source/JavaScriptCore/bytecompiler/BytecodeGenerator.cpp:
(JSC::BytecodeGenerator::BytecodeGenerator):
* Source/JavaScriptCore/bytecompiler/BytecodeGenerator.h:
(JSC::BytecodeGenerator::useGetArgumentsLengthFast):
* Source/JavaScriptCore/bytecompiler/NodesCodegen.cpp:
(JSC::DotAccessorNode::emitBytecode):
* Source/JavaScriptCore/parser/ASTBuilder.h:
(JSC::ASTBuilder::createDotAccess):
(JSC::ASTBuilder::createAssignment):
(JSC::ASTBuilder::createAssignmentElement):
(JSC::ASTBuilder::checkAssignmentForArguments):
(JSC::ASTBuilder::useArgumentsOnlyForReadingLength):
(JSC::ASTBuilder::usesArguments):
* Source/JavaScriptCore/parser/Nodes.h:
(JSC::ExpressionNode::isArgumentsAccess const):
(JSC::ExpressionNode::isArgumentsLengthAccess const):
(JSC::ExpressionNode::isArguments const):
(JSC::ScopeNode::useGetArgumentsLengthFast const):
* Source/JavaScriptCore/parser/Parser.cpp:
(JSC::Parser<LexerType>::parseInner):
* Source/JavaScriptCore/parser/Parser.h:
(JSC::Scope::hasDeclaredArguments const):
(JSC::Scope::setHasDeclaredArguments):
(JSC::Scope::declareCallee):
(JSC::Scope::declareVariable):
(JSC::Scope::declareFunction):
(JSC::Scope::declareLexicalVariable):
(JSC::Scope::addDeclaredVariable):
(JSC::Scope::addDeclareLexicalVariable):
(JSC::Scope::addDeclaredParameters):
(JSC::Scope::declareParameter):
(JSC::Scope::getSloppyModeHoistedFunctions):
(JSC::Scope::setReadArgumentsLengthOnly):
(JSC::Scope::useGetArgumentsLengthFast const):
(JSC::Parser::popScopeInternal):
* Source/JavaScriptCore/parser/ParserModes.h:
* Source/JavaScriptCore/parser/VariableEnvironment.h:

Canonical link: https://commits.webkit.org/268480@main