[webkit-changes] [WebKit/WebKit] 3e0dc2: [JSC] Do not declare callee name when it is functi...

[Yusuke Suzuki]

  Branch: refs/heads/main
  Home:   https://github.com/WebKit/WebKit
  Commit: 3e0dc21a287b581aa7645a438b07c3c38745cd51
      https://github.com/WebKit/WebKit/commit/3e0dc21a287b581aa7645a438b07c3c38745cd51
  Author: Yusuke Suzuki <ysuzuki at apple.com>
  Date:   2023-11-01 (Wed, 01 Nov 2023)

  Changed paths:
    A JSTests/microbenchmarks/function-declaration-name.js
    M Source/JavaScriptCore/API/JSScriptRef.cpp
    M Source/JavaScriptCore/API/glib/JSCContext.cpp
    M Source/JavaScriptCore/builtins/BuiltinExecutables.cpp
    M Source/JavaScriptCore/bytecode/UnlinkedFunctionExecutable.cpp
    M Source/JavaScriptCore/debugger/DebuggerParseData.cpp
    M Source/JavaScriptCore/parser/Parser.cpp
    M Source/JavaScriptCore/parser/Parser.h
    M Source/JavaScriptCore/parser/ParserModes.h
    M Source/JavaScriptCore/runtime/CodeCache.cpp
    M Source/JavaScriptCore/runtime/Completion.cpp
    M Source/JavaScriptCore/runtime/JSModuleLoader.cpp

  Log Message:
  -----------
  [JSC] Do not declare callee name when it is function declaration
https://bugs.webkit.org/show_bug.cgi?id=264030
rdar://117786144

Reviewed by Alexey Shvayka.

We should declare callee only when it is not function declarations. Otherwise, we taint the scope with that,
and unnecessarily create a JSLexicalEnvironment when it gets captured.

    function test(n) {
        if (n) {
            (function(n) {
                test(n - 1);
            }(n));
        }
    }

In the above code, if `test` function is function declaration, we should define `test` name in the upper scope
and we do not need to declare it inside the function.
We propagate FunctionMode in Parser and use it as the same way to BytecodeGenerator.

Microbenchmark shows improvement since we wipe JSLexicalEnvironment allocations.

                                          ToT                     Patched

    function-declaration-name       32.8020+-0.3279     ^     27.4767+-0.2500        ^ definitely 1.1938x faster

* Source/JavaScriptCore/API/JSScriptRef.cpp:
(parseScript):
* Source/JavaScriptCore/API/glib/JSCContext.cpp:
(jsc_context_check_syntax):
* Source/JavaScriptCore/builtins/BuiltinExecutables.cpp:
(JSC::BuiltinExecutables::createExecutable):
* Source/JavaScriptCore/bytecode/UnlinkedFunctionExecutable.cpp:
(JSC::generateUnlinkedFunctionCodeBlock):
* Source/JavaScriptCore/debugger/DebuggerParseData.cpp:
(JSC::gatherDebuggerParseData):
* Source/JavaScriptCore/parser/Parser.cpp:
(JSC::Parser<LexerType>::Parser):
(JSC::Parser<LexerType>::parseInner):
* Source/JavaScriptCore/parser/Parser.h:
(JSC::Parser::functionMode const):
(JSC::parse):
(JSC::parseFunctionForFunctionConstructor):
* Source/JavaScriptCore/parser/ParserModes.h:
* Source/JavaScriptCore/runtime/CodeCache.cpp:
(JSC::generateUnlinkedCodeBlockImpl):
* Source/JavaScriptCore/runtime/Completion.cpp:
(JSC::checkSyntaxInternal):
(JSC::checkModuleSyntax):
* Source/JavaScriptCore/runtime/JSModuleLoader.cpp:
(JSC::JSC_DEFINE_HOST_FUNCTION):

Canonical link: https://commits.webkit.org/270095@main