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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 19:33:14 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 19:33:14 +0000
commit36d22d82aa202bb199967e9512281e9a53db42c9 (patch)
tree105e8c98ddea1c1e4784a60a5a6410fa416be2de /js/src/frontend/ParseContext.h
parentInitial commit. (diff)
downloadfirefox-esr-36d22d82aa202bb199967e9512281e9a53db42c9.tar.xz
firefox-esr-36d22d82aa202bb199967e9512281e9a53db42c9.zip
Adding upstream version 115.7.0esr.upstream/115.7.0esrupstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'js/src/frontend/ParseContext.h')
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+/* -*- 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_ParseContext_h
+#define frontend_ParseContext_h
+
+#include "ds/Nestable.h"
+#include "frontend/ErrorReporter.h"
+#include "frontend/NameAnalysisTypes.h" // DeclaredNameInfo, FunctionBoxVector
+#include "frontend/NameCollections.h"
+#include "frontend/ParserAtom.h" // TaggedParserAtomIndex
+#include "frontend/ScriptIndex.h" // ScriptIndex
+#include "frontend/SharedContext.h"
+#include "js/friend/ErrorMessages.h" // JSMSG_*
+#include "vm/GeneratorAndAsyncKind.h" // js::GeneratorKind, js::FunctionAsyncKind
+#include "vm/WellKnownAtom.h" // js_*_str
+
+namespace js {
+
+namespace frontend {
+
+class ParserBase;
+class UsedNameTracker;
+
+struct CompilationState;
+
+const char* DeclarationKindString(DeclarationKind kind);
+
+// Returns true if the declaration is `var` or equivalent.
+bool DeclarationKindIsVar(DeclarationKind kind);
+
+bool DeclarationKindIsParameter(DeclarationKind kind);
+
+/*
+ * The struct ParseContext stores information about the current parsing context,
+ * which is part of the parser state (see the field Parser::pc). The current
+ * parsing context is either the global context, or the function currently being
+ * parsed. When the parser encounters a function definition, it creates a new
+ * ParseContext, makes it the new current context.
+ */
+class ParseContext : public Nestable<ParseContext> {
+ public:
+ // The intra-function statement stack.
+ //
+ // Used for early error checking that depend on the nesting structure of
+ // statements, such as continue/break targets, labels, and unbraced
+ // lexical declarations.
+ class Statement : public Nestable<Statement> {
+ StatementKind kind_;
+
+ public:
+ using Nestable<Statement>::enclosing;
+ using Nestable<Statement>::findNearest;
+
+ Statement(ParseContext* pc, StatementKind kind)
+ : Nestable<Statement>(&pc->innermostStatement_), kind_(kind) {}
+
+ template <typename T>
+ inline bool is() const;
+ template <typename T>
+ inline T& as();
+
+ StatementKind kind() const { return kind_; }
+
+ void refineForKind(StatementKind newForKind) {
+ MOZ_ASSERT(kind_ == StatementKind::ForLoop);
+ MOZ_ASSERT(newForKind == StatementKind::ForInLoop ||
+ newForKind == StatementKind::ForOfLoop);
+ kind_ = newForKind;
+ }
+ };
+
+ class LabelStatement : public Statement {
+ TaggedParserAtomIndex label_;
+
+ public:
+ LabelStatement(ParseContext* pc, TaggedParserAtomIndex label)
+ : Statement(pc, StatementKind::Label), label_(label) {}
+
+ TaggedParserAtomIndex label() const { return label_; }
+ };
+
+ struct ClassStatement : public Statement {
+ FunctionBox* constructorBox;
+
+ explicit ClassStatement(ParseContext* pc)
+ : Statement(pc, StatementKind::Class), constructorBox(nullptr) {}
+ };
+
+ // The intra-function scope stack.
+ //
+ // Tracks declared and used names within a scope.
+ class Scope : public Nestable<Scope> {
+ // Names declared in this scope. Corresponds to the union of
+ // VarDeclaredNames and LexicallyDeclaredNames in the ES spec.
+ //
+ // A 'var' declared name is a member of the declared name set of every
+ // scope in its scope contour.
+ //
+ // A lexically declared name is a member only of the declared name set of
+ // the scope in which it is declared.
+ PooledMapPtr<DeclaredNameMap> declared_;
+
+ // FunctionBoxes in this scope that need to be considered for Annex
+ // B.3.3 semantics. This is checked on Scope exit, as by then we have
+ // all the declared names and would know if Annex B.3.3 is applicable.
+ PooledVectorPtr<FunctionBoxVector> possibleAnnexBFunctionBoxes_;
+
+ // Monotonically increasing id.
+ uint32_t id_;
+
+ // Scope size info, relevant for scopes in generators and async functions
+ // only. During parsing, this is the estimated number of slots needed for
+ // nested scopes inside this one. When the parser leaves a scope, this is
+ // set to UINT32_MAX if there are too many bindings overrall to store them
+ // in stack frames, and 0 otherwise.
+ uint32_t sizeBits_ = 0;
+
+ bool maybeReportOOM(ParseContext* pc, bool result) {
+ if (!result) {
+ ReportOutOfMemory(pc->sc()->fc_);
+ }
+ return result;
+ }
+
+ public:
+ using DeclaredNamePtr = DeclaredNameMap::Ptr;
+ using AddDeclaredNamePtr = DeclaredNameMap::AddPtr;
+
+ using Nestable<Scope>::enclosing;
+
+ explicit inline Scope(ParserBase* parser);
+ explicit inline Scope(FrontendContext* fc, ParseContext* pc,
+ UsedNameTracker& usedNames);
+
+ void dump(ParseContext* pc, ParserBase* parser);
+
+ uint32_t id() const { return id_; }
+
+ [[nodiscard]] bool init(ParseContext* pc) {
+ if (id_ == UINT32_MAX) {
+ pc->errorReporter_.errorNoOffset(JSMSG_NEED_DIET, js_script_str);
+ return false;
+ }
+
+ return declared_.acquire(pc->sc()->fc_);
+ }
+
+ bool isEmpty() const { return declared_->all().empty(); }
+
+ uint32_t declaredCount() const {
+ size_t count = declared_->count();
+ MOZ_ASSERT(count <= UINT32_MAX);
+ return uint32_t(count);
+ }
+
+ DeclaredNamePtr lookupDeclaredName(TaggedParserAtomIndex name) {
+ return declared_->lookup(name);
+ }
+
+ AddDeclaredNamePtr lookupDeclaredNameForAdd(TaggedParserAtomIndex name) {
+ return declared_->lookupForAdd(name);
+ }
+
+ [[nodiscard]] bool addDeclaredName(ParseContext* pc, AddDeclaredNamePtr& p,
+ TaggedParserAtomIndex name,
+ DeclarationKind kind, uint32_t pos,
+ ClosedOver closedOver = ClosedOver::No) {
+ return maybeReportOOM(
+ pc, declared_->add(p, name, DeclaredNameInfo(kind, pos, closedOver)));
+ }
+
+ // Add a FunctionBox as a possible candidate for Annex B.3.3 semantics.
+ [[nodiscard]] bool addPossibleAnnexBFunctionBox(ParseContext* pc,
+ FunctionBox* funbox);
+
+ // Check if the candidate function boxes for Annex B.3.3 should in
+ // fact get Annex B semantics. Checked on Scope exit.
+ [[nodiscard]] bool propagateAndMarkAnnexBFunctionBoxes(ParseContext* pc,
+ ParserBase* parser);
+
+ // Add and remove catch parameter names. Used to implement the odd
+ // semantics of catch bodies.
+ bool addCatchParameters(ParseContext* pc, Scope& catchParamScope);
+ void removeCatchParameters(ParseContext* pc, Scope& catchParamScope);
+
+ void useAsVarScope(ParseContext* pc) {
+ MOZ_ASSERT(!pc->varScope_);
+ pc->varScope_ = this;
+ }
+
+ // Maximum number of fixed stack slots in a generator or async function
+ // script. If a script would have more, we instead store some variables in
+ // heap EnvironmentObjects.
+ //
+ // This limit is a performance heuristic. Stack slots reduce allocations,
+ // and `Local` opcodes are a bit faster than `AliasedVar` ones; but at each
+ // `yield` or `await` the stack slots must be memcpy'd into a
+ // GeneratorObject. At some point the memcpy is too much. The limit is
+ // plenty for typical human-authored code.
+ static constexpr uint32_t FixedSlotLimit = 256;
+
+ // This is called as we leave a function, var, or lexical scope in a
+ // generator or async function. `ownSlotCount` is the number of `bindings_`
+ // that are not closed over.
+ void setOwnStackSlotCount(uint32_t ownSlotCount) {
+ // Determine if this scope is too big to optimize bindings into stack
+ // slots. The meaning of sizeBits_ changes from "maximum nested slot
+ // count" to "UINT32_MAX if too big".
+ uint32_t slotCount = ownSlotCount + sizeBits_;
+ if (slotCount > FixedSlotLimit) {
+ slotCount = sizeBits_;
+ sizeBits_ = UINT32_MAX;
+ } else {
+ sizeBits_ = 0;
+ }
+
+ // Propagate total size to enclosing scope.
+ if (Scope* parent = enclosing()) {
+ if (slotCount > parent->sizeBits_) {
+ parent->sizeBits_ = slotCount;
+ }
+ }
+ }
+
+ bool tooBigToOptimize() const {
+ MOZ_ASSERT(sizeBits_ == 0 || sizeBits_ == UINT32_MAX,
+ "call this only after the parser leaves the scope");
+ return sizeBits_ != 0;
+ }
+
+ // An iterator for the set of names a scope binds: the set of all
+ // declared names for 'var' scopes, and the set of lexically declared
+ // names, plus synthetic names, for non-'var' scopes.
+ class BindingIter {
+ friend class Scope;
+
+ DeclaredNameMap::Range declaredRange_;
+ mozilla::DebugOnly<uint32_t> count_;
+ bool isVarScope_;
+
+ BindingIter(Scope& scope, bool isVarScope)
+ : declaredRange_(scope.declared_->all()),
+ count_(0),
+ isVarScope_(isVarScope) {
+ settle();
+ }
+
+ bool isLexicallyDeclared() {
+ return BindingKindIsLexical(kind()) ||
+ kind() == BindingKind::Synthetic ||
+ kind() == BindingKind::PrivateMethod;
+ }
+
+ void settle() {
+ // Both var and lexically declared names are binding in a var
+ // scope.
+ if (isVarScope_) {
+ return;
+ }
+
+ // Otherwise, only lexically declared names are binding. Pop the range
+ // until we find such a name.
+ while (!declaredRange_.empty()) {
+ if (isLexicallyDeclared()) {
+ break;
+ }
+ declaredRange_.popFront();
+ }
+ }
+
+ public:
+ bool done() const { return declaredRange_.empty(); }
+
+ explicit operator bool() const { return !done(); }
+
+ TaggedParserAtomIndex name() {
+ MOZ_ASSERT(!done());
+ return declaredRange_.front().key();
+ }
+
+ DeclarationKind declarationKind() {
+ MOZ_ASSERT(!done());
+ return declaredRange_.front().value()->kind();
+ }
+
+ BindingKind kind() {
+ return DeclarationKindToBindingKind(declarationKind());
+ }
+
+ bool closedOver() {
+ MOZ_ASSERT(!done());
+ return declaredRange_.front().value()->closedOver();
+ }
+
+ void setClosedOver() {
+ MOZ_ASSERT(!done());
+ return declaredRange_.front().value()->setClosedOver();
+ }
+
+ void operator++(int) {
+ MOZ_ASSERT(!done());
+ MOZ_ASSERT(count_ != UINT32_MAX);
+ declaredRange_.popFront();
+ settle();
+ }
+ };
+
+ inline BindingIter bindings(ParseContext* pc);
+ };
+
+ class VarScope : public Scope {
+ public:
+ explicit inline VarScope(ParserBase* parser);
+ explicit inline VarScope(FrontendContext* fc, ParseContext* pc,
+ UsedNameTracker& usedNames);
+ };
+
+ private:
+ // Context shared between parsing and bytecode generation.
+ SharedContext* sc_;
+
+ // A mechanism used for error reporting.
+ ErrorReporter& errorReporter_;
+
+ // The innermost statement, i.e., top of the statement stack.
+ Statement* innermostStatement_;
+
+ // The innermost scope, i.e., top of the scope stack.
+ //
+ // The outermost scope in the stack is usually varScope_. In the case of
+ // functions, the outermost scope is functionScope_, which may be
+ // varScope_. See comment above functionScope_.
+ Scope* innermostScope_;
+
+ // If isFunctionBox() and the function is a named lambda, the DeclEnv
+ // scope for named lambdas.
+ mozilla::Maybe<Scope> namedLambdaScope_;
+
+ // If isFunctionBox(), the scope for the function. If there are no
+ // parameter expressions, this is scope for the entire function. If there
+ // are parameter expressions, this holds the special function names
+ // ('.this', 'arguments') and the formal parameters.
+ mozilla::Maybe<Scope> functionScope_;
+
+ // The body-level scope. This always exists, but not necessarily at the
+ // beginning of parsing the script in the case of functions with parameter
+ // expressions.
+ Scope* varScope_;
+
+ // Simple formal parameter names, in order of appearance. Only used when
+ // isFunctionBox().
+ PooledVectorPtr<AtomVector> positionalFormalParameterNames_;
+
+ // Closed over binding names, in order of appearance. Null-delimited
+ // between scopes. Only used when syntax parsing.
+ PooledVectorPtr<AtomVector> closedOverBindingsForLazy_;
+
+ public:
+ // All inner functions in this context. Only used when syntax parsing.
+ // The Functions (or FunctionCreateionDatas) are traced as part of the
+ // CompilationStencil function vector.
+ Vector<ScriptIndex, 4> innerFunctionIndexesForLazy;
+
+ // In a function context, points to a Directive struct that can be updated
+ // to reflect new directives encountered in the Directive Prologue that
+ // require reparsing the function. In global/module/generator-tail contexts,
+ // we don't need to reparse when encountering a DirectivePrologue so this
+ // pointer may be nullptr.
+ Directives* newDirectives;
+
+ // lastYieldOffset stores the offset of the last yield that was parsed.
+ // NoYieldOffset is its initial value.
+ static const uint32_t NoYieldOffset = UINT32_MAX;
+ uint32_t lastYieldOffset;
+
+ // lastAwaitOffset stores the offset of the last await that was parsed.
+ // NoAwaitOffset is its initial value.
+ static const uint32_t NoAwaitOffset = UINT32_MAX;
+ uint32_t lastAwaitOffset;
+
+ private:
+ // Monotonically increasing id.
+ uint32_t scriptId_;
+
+ // Set when encountering a super.property inside a method. We need to mark
+ // the nearest super scope as needing a home object.
+ bool superScopeNeedsHomeObject_;
+
+ public:
+ ParseContext(FrontendContext* fc, ParseContext*& parent, SharedContext* sc,
+ ErrorReporter& errorReporter, CompilationState& compilationState,
+ Directives* newDirectives, bool isFull);
+
+ [[nodiscard]] bool init();
+
+ SharedContext* sc() { return sc_; }
+
+ // `true` if we are in the body of a function definition.
+ bool isFunctionBox() const { return sc_->isFunctionBox(); }
+
+ FunctionBox* functionBox() { return sc_->asFunctionBox(); }
+
+ Statement* innermostStatement() { return innermostStatement_; }
+
+ Scope* innermostScope() {
+ // There is always at least one scope: the 'var' scope.
+ MOZ_ASSERT(innermostScope_);
+ return innermostScope_;
+ }
+
+ Scope& namedLambdaScope() {
+ MOZ_ASSERT(functionBox()->isNamedLambda());
+ return *namedLambdaScope_;
+ }
+
+ Scope& functionScope() {
+ MOZ_ASSERT(isFunctionBox());
+ return *functionScope_;
+ }
+
+ Scope& varScope() {
+ MOZ_ASSERT(varScope_);
+ return *varScope_;
+ }
+
+ bool isFunctionExtraBodyVarScopeInnermost() {
+ return isFunctionBox() && functionBox()->hasParameterExprs &&
+ innermostScope() == varScope_;
+ }
+
+ template <typename Predicate /* (Statement*) -> bool */>
+ Statement* findInnermostStatement(Predicate predicate) {
+ return Statement::findNearest(innermostStatement_, predicate);
+ }
+
+ template <typename T, typename Predicate /* (Statement*) -> bool */>
+ T* findInnermostStatement(Predicate predicate) {
+ return Statement::findNearest<T>(innermostStatement_, predicate);
+ }
+
+ template <typename T>
+ T* findInnermostStatement() {
+ return Statement::findNearest<T>(innermostStatement_);
+ }
+
+ AtomVector& positionalFormalParameterNames() {
+ return *positionalFormalParameterNames_;
+ }
+
+ AtomVector& closedOverBindingsForLazy() {
+ return *closedOverBindingsForLazy_;
+ }
+
+ enum class BreakStatementError : uint8_t {
+ // Unlabeled break must be inside loop or switch.
+ ToughBreak,
+ LabelNotFound,
+ };
+
+ // Return Err(true) if we have encountered at least one loop,
+ // Err(false) otherwise.
+ [[nodiscard]] inline JS::Result<Ok, BreakStatementError> checkBreakStatement(
+ TaggedParserAtomIndex label);
+
+ enum class ContinueStatementError : uint8_t {
+ NotInALoop,
+ LabelNotFound,
+ };
+ [[nodiscard]] inline JS::Result<Ok, ContinueStatementError>
+ checkContinueStatement(TaggedParserAtomIndex label);
+
+ // True if we are at the topmost level of a entire script or function body.
+ // For example, while parsing this code we would encounter f1 and f2 at
+ // body level, but we would not encounter f3 or f4 at body level:
+ //
+ // function f1() { function f2() { } }
+ // if (cond) { function f3() { if (cond) { function f4() { } } } }
+ //
+ bool atBodyLevel() { return !innermostStatement_; }
+
+ bool atGlobalLevel() { return atBodyLevel() && sc_->isGlobalContext(); }
+
+ // True if we are at the topmost level of a module only.
+ bool atModuleLevel() { return atBodyLevel() && sc_->isModuleContext(); }
+
+ // True if we are at the topmost level of an entire script or module. For
+ // example, in the comment on |atBodyLevel()| above, we would encounter |f1|
+ // and the outermost |if (cond)| at top level, and everything else would not
+ // be at top level.
+ bool atTopLevel() { return atBodyLevel() && sc_->isTopLevelContext(); }
+
+ bool atModuleTopLevel() {
+ // True if we are at the topmost level of an entire module.
+ //
+ // For example, this is used to determine if an await statement should
+ // mark a module as an async module during parsing.
+ //
+ // Example module:
+ // import x from "y";
+ //
+ // await x.foo(); // mark as Top level await.
+ //
+ // if (cond) {
+ // await x.bar(); // mark as Top level await.
+ // }
+ //
+ // async function z() {
+ // await x.baz(); // do not mark as Top level await.
+ // }
+ return sc_->isModuleContext() && sc_->isTopLevelContext();
+ }
+
+ // True if this is the outermost ParserContext for current compile. For
+ // delazification, this lets us identify if the lazy PrivateScriptData is for
+ // current parser context.
+ bool isOutermostOfCurrentCompile() const {
+ MOZ_ASSERT(!!enclosing() == !!scriptId());
+ return (scriptId() == 0);
+ }
+
+ void setSuperScopeNeedsHomeObject() {
+ MOZ_ASSERT(sc_->allowSuperProperty());
+ superScopeNeedsHomeObject_ = true;
+ }
+
+ bool superScopeNeedsHomeObject() const { return superScopeNeedsHomeObject_; }
+
+ bool useAsmOrInsideUseAsm() const {
+ return sc_->isFunctionBox() && sc_->asFunctionBox()->useAsmOrInsideUseAsm();
+ }
+
+ // A generator is marked as a generator before its body is parsed.
+ GeneratorKind generatorKind() const {
+ return sc_->isFunctionBox() ? sc_->asFunctionBox()->generatorKind()
+ : GeneratorKind::NotGenerator;
+ }
+
+ bool isGenerator() const {
+ return generatorKind() == GeneratorKind::Generator;
+ }
+
+ bool isAsync() const {
+ return sc_->isSuspendableContext() &&
+ sc_->asSuspendableContext()->isAsync();
+ }
+
+ bool isGeneratorOrAsync() const { return isGenerator() || isAsync(); }
+
+ bool needsDotGeneratorName() const { return isGeneratorOrAsync(); }
+
+ FunctionAsyncKind asyncKind() const {
+ return isAsync() ? FunctionAsyncKind::AsyncFunction
+ : FunctionAsyncKind::SyncFunction;
+ }
+
+ bool isArrowFunction() const {
+ return sc_->isFunctionBox() && sc_->asFunctionBox()->isArrow();
+ }
+
+ bool isMethod() const {
+ return sc_->isFunctionBox() && sc_->asFunctionBox()->isMethod();
+ }
+
+ bool isGetterOrSetter() const {
+ return sc_->isFunctionBox() && (sc_->asFunctionBox()->isGetter() ||
+ sc_->asFunctionBox()->isSetter());
+ }
+
+ bool allowReturn() const {
+ return sc_->isFunctionBox() && sc_->asFunctionBox()->allowReturn();
+ }
+
+ uint32_t scriptId() const { return scriptId_; }
+
+ bool computeAnnexBAppliesToLexicalFunctionInInnermostScope(
+ FunctionBox* funbox, ParserBase* parser, bool* annexBApplies);
+
+ bool tryDeclareVar(TaggedParserAtomIndex name, ParserBase* parser,
+ DeclarationKind kind, uint32_t beginPos,
+ mozilla::Maybe<DeclarationKind>* redeclaredKind,
+ uint32_t* prevPos);
+
+ bool hasUsedName(const UsedNameTracker& usedNames,
+ TaggedParserAtomIndex name);
+ bool hasUsedFunctionSpecialName(const UsedNameTracker& usedNames,
+ TaggedParserAtomIndex name);
+
+ bool declareFunctionThis(const UsedNameTracker& usedNames,
+ bool canSkipLazyClosedOverBindings);
+ bool declareFunctionArgumentsObject(const UsedNameTracker& usedNames,
+ bool canSkipLazyClosedOverBindings);
+ bool declareNewTarget(const UsedNameTracker& usedNames,
+ bool canSkipLazyClosedOverBindings);
+ bool declareDotGeneratorName();
+ bool declareTopLevelDotGeneratorName();
+
+ private:
+ [[nodiscard]] bool isVarRedeclaredInInnermostScope(
+ TaggedParserAtomIndex name, ParserBase* parser, DeclarationKind kind,
+ mozilla::Maybe<DeclarationKind>* out);
+
+ [[nodiscard]] bool isVarRedeclaredInEval(
+ TaggedParserAtomIndex name, ParserBase* parser, DeclarationKind kind,
+ mozilla::Maybe<DeclarationKind>* out);
+
+ enum DryRunOption { NotDryRun, DryRunInnermostScopeOnly };
+ template <DryRunOption dryRunOption>
+ bool tryDeclareVarHelper(TaggedParserAtomIndex name, ParserBase* parser,
+ DeclarationKind kind, uint32_t beginPos,
+ mozilla::Maybe<DeclarationKind>* redeclaredKind,
+ uint32_t* prevPos);
+};
+
+} // namespace frontend
+
+} // namespace js
+
+#endif // frontend_ParseContext_h