[webkit-changes] [WebKit/WebKit] 5fc313: [JSC] Avoid saving top-level scope for non-module ...

[Tadeu Zagallo]

  Branch: refs/heads/main
  Home:   https://github.com/WebKit/WebKit
  Commit: 5fc313f94632beae308222510df47f48b9e6b866
      https://github.com/WebKit/WebKit/commit/5fc313f94632beae308222510df47f48b9e6b866
  Author: Tadeu Zagallo <tzagallo at apple.com>
  Date:   2023-02-23 (Thu, 23 Feb 2023)

  Changed paths:
    M JSTests/stress/call-link-info-osrexit-repatch.js
    A JSTests/stress/hoisted-eval-different-scope.js
    M Source/JavaScriptCore/bytecompiler/BytecodeGenerator.cpp
    M Source/JavaScriptCore/bytecompiler/BytecodeGenerator.h

  Log Message:
  -----------
  [JSC] Avoid saving top-level scope for non-module code
https://bugs.webkit.org/show_bug.cgi?id=252674
rdar://105732218

Reviewed by Yusuke Suzuki.

Avoid allocating a local variable and moving the scope to save the top-level
scope. Re-loading the context is pretty cheap and this reduces the amount of
bytecode overhead for small functions. Notice that we still allocate a variable
for module code, which is necessary since we allocate a lexical environment,
which needs the scope for variable resolution.

* JSTests/stress/hoisted-eval-different-scope.js: Added.
(i.with.g):
(i.g.f):
(i.g):
* Source/JavaScriptCore/bytecompiler/BytecodeGenerator.cpp:
(JSC::BytecodeGenerator::BytecodeGenerator):
(JSC::BytecodeGenerator::emitResolveScopeForHoistingFuncDeclInEval):
(JSC::BytecodeGenerator::allocateAndEmitScope):
(JSC::BytecodeGenerator::restoreScopeRegister):

Canonical link: https://commits.webkit.org/260743@main