From 2aa4a82499d4becd2284cdb482213d541b8804dd Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sun, 28 Apr 2024 16:29:10 +0200 Subject: Adding upstream version 86.0.1. Signed-off-by: Daniel Baumann --- js/src/frontend/TDZCheckCache.h | 58 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 58 insertions(+) create mode 100644 js/src/frontend/TDZCheckCache.h (limited to 'js/src/frontend/TDZCheckCache.h') diff --git a/js/src/frontend/TDZCheckCache.h b/js/src/frontend/TDZCheckCache.h new file mode 100644 index 0000000000..b8c143c80b --- /dev/null +++ b/js/src/frontend/TDZCheckCache.h @@ -0,0 +1,58 @@ +/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- + * vim: set ts=8 sts=2 et sw=2 tw=80: + * This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ + +#ifndef frontend_TDZCheckCache_h +#define frontend_TDZCheckCache_h + +#include "mozilla/Attributes.h" +#include "mozilla/Maybe.h" + +#include "ds/Nestable.h" +#include "frontend/NameCollections.h" +#include "js/TypeDecls.h" +#include "vm/Stack.h" + +namespace js { +namespace frontend { + +struct BytecodeEmitter; + +using CheckTDZMap = RecyclableNameMap; + +// A cache that tracks Temporal Dead Zone (TDZ) checks, so that any use of a +// lexical variable that's dominated by an earlier use, or by evaluation of its +// declaration (which will initialize it, perhaps to |undefined|), doesn't have +// to redundantly check that the lexical variable has been initialized +// +// Each basic block should have a TDZCheckCache in scope. Some NestableControl +// subclasses contain a TDZCheckCache. +// +// When a scope containing lexical variables is entered, all such variables are +// marked as CheckTDZ. When a lexical variable is accessed, its entry is +// checked. If it's CheckTDZ, a JSOp::CheckLexical is emitted and then the +// entry is marked DontCheckTDZ. If it's DontCheckTDZ, no check is emitted +// because a prior check would have already failed. Finally, because +// evaluating a lexical variable declaration initializes it (after any +// initializer is evaluated), evaluating a lexical declaration marks its entry +// as DontCheckTDZ. +class TDZCheckCache : public Nestable { + PooledMapPtr cache_; + + MOZ_MUST_USE bool ensureCache(BytecodeEmitter* bce); + + public: + explicit TDZCheckCache(BytecodeEmitter* bce); + + mozilla::Maybe needsTDZCheck(BytecodeEmitter* bce, + const ParserAtom* name); + MOZ_MUST_USE bool noteTDZCheck(BytecodeEmitter* bce, const ParserAtom* name, + MaybeCheckTDZ check); +}; + +} /* namespace frontend */ +} /* namespace js */ + +#endif /* frontend_TDZCheckCache_h */ -- cgit v1.2.3