| /* |
| * Copyright (C) 2012-2015 Apple Inc. All Rights Reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * 1. Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * 2. Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in the |
| * documentation and/or other materials provided with the distribution. |
| * |
| * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY |
| * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
| * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR |
| * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, |
| * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, |
| * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR |
| * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY |
| * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| */ |
| |
| #include "config.h" |
| #include "JSScope.h" |
| |
| #include "JSGlobalObject.h" |
| #include "JSLexicalEnvironment.h" |
| #include "JSModuleEnvironment.h" |
| #include "JSModuleRecord.h" |
| #include "JSWithScope.h" |
| #include "JSCInlines.h" |
| |
| namespace JSC { |
| |
| STATIC_ASSERT_IS_TRIVIALLY_DESTRUCTIBLE(JSScope); |
| |
| void JSScope::visitChildren(JSCell* cell, SlotVisitor& visitor) |
| { |
| JSScope* thisObject = jsCast<JSScope*>(cell); |
| ASSERT_GC_OBJECT_INHERITS(thisObject, info()); |
| Base::visitChildren(thisObject, visitor); |
| visitor.append(&thisObject->m_next); |
| } |
| |
| // Returns true if we found enough information to terminate optimization. |
| static inline bool abstractAccess(ExecState* exec, JSScope* scope, const Identifier& ident, GetOrPut getOrPut, size_t depth, bool& needsVarInjectionChecks, ResolveOp& op, InitializationMode initializationMode) |
| { |
| if (JSLexicalEnvironment* lexicalEnvironment = jsDynamicCast<JSLexicalEnvironment*>(scope)) { |
| if (ident == exec->propertyNames().arguments) { |
| // We know the property will be at this lexical environment scope, but we don't know how to cache it. |
| op = ResolveOp(Dynamic, 0, 0, 0, 0, 0); |
| return true; |
| } |
| |
| SymbolTableEntry entry = lexicalEnvironment->symbolTable()->get(ident.impl()); |
| if (entry.isReadOnly() && getOrPut == Put) { |
| // We know the property will be at this lexical environment scope, but we don't know how to cache it. |
| op = ResolveOp(Dynamic, 0, 0, 0, 0, 0); |
| return true; |
| } |
| |
| if (!entry.isNull()) { |
| op = ResolveOp(makeType(ClosureVar, needsVarInjectionChecks), depth, 0, lexicalEnvironment, entry.watchpointSet(), entry.scopeOffset().offset()); |
| return true; |
| } |
| |
| if (JSModuleEnvironment* moduleEnvironment = jsDynamicCast<JSModuleEnvironment*>(scope)) { |
| JSModuleRecord* moduleRecord = moduleEnvironment->moduleRecord(); |
| JSModuleRecord::Resolution resolution = moduleRecord->resolveImport(exec, ident); |
| if (resolution.type == JSModuleRecord::Resolution::Type::Resolved) { |
| JSModuleRecord* importedRecord = resolution.moduleRecord; |
| JSModuleEnvironment* importedEnvironment = importedRecord->moduleEnvironment(); |
| SymbolTableEntry entry = importedEnvironment->symbolTable()->get(resolution.localName.impl()); |
| ASSERT(!entry.isNull()); |
| op = ResolveOp(makeType(ModuleVar, needsVarInjectionChecks), depth, 0, importedEnvironment, entry.watchpointSet(), entry.scopeOffset().offset(), resolution.localName.impl()); |
| return true; |
| } |
| } |
| |
| if (lexicalEnvironment->symbolTable()->usesNonStrictEval()) |
| needsVarInjectionChecks = true; |
| return false; |
| } |
| |
| if (JSGlobalLexicalEnvironment* globalLexicalEnvironment = jsDynamicCast<JSGlobalLexicalEnvironment*>(scope)) { |
| SymbolTableEntry entry = globalLexicalEnvironment->symbolTable()->get(ident.impl()); |
| if (!entry.isNull()) { |
| if (getOrPut == Put && entry.isReadOnly() && initializationMode != Initialization) { |
| // We know the property will be at global lexical environment, but we don't know how to cache it. |
| op = ResolveOp(Dynamic, 0, 0, 0, 0, 0); |
| return true; |
| } |
| |
| // We can try to force const Initialization to always go down the fast path. It is provably impossible to construct |
| // a program that needs a var injection check here. You can convince yourself of this as follows: |
| // Any other let/const/class would be a duplicate of this in the global scope, so we would never get here in that situation. |
| // Also, if we had an eval in the global scope that defined a const, it would also be a duplicate of this const, and so it would |
| // also throw an error. Therefore, we're *the only* thing that can assign to this "const" slot for the first (and only) time. Also, |
| // we will never have a Dynamic ResolveType here because if we were inside a "with" statement, that would mean the "const" definition |
| // isn't a global, it would be a local to the "with" block. |
| // We still need to make the slow path correct for when we need to fire a watchpoint. |
| ResolveType resolveType = initializationMode == Initialization ? GlobalLexicalVar : makeType(GlobalLexicalVar, needsVarInjectionChecks); |
| op = ResolveOp( |
| resolveType, depth, 0, 0, entry.watchpointSet(), |
| reinterpret_cast<uintptr_t>(globalLexicalEnvironment->variableAt(entry.scopeOffset()).slot())); |
| return true; |
| } |
| |
| return false; |
| } |
| |
| if (JSGlobalObject* globalObject = jsDynamicCast<JSGlobalObject*>(scope)) { |
| SymbolTableEntry entry = globalObject->symbolTable()->get(ident.impl()); |
| if (!entry.isNull()) { |
| if (getOrPut == Put && entry.isReadOnly()) { |
| // We know the property will be at global scope, but we don't know how to cache it. |
| op = ResolveOp(Dynamic, 0, 0, 0, 0, 0); |
| return true; |
| } |
| |
| op = ResolveOp( |
| makeType(GlobalVar, needsVarInjectionChecks), depth, 0, 0, entry.watchpointSet(), |
| reinterpret_cast<uintptr_t>(globalObject->variableAt(entry.scopeOffset()).slot())); |
| return true; |
| } |
| |
| PropertySlot slot(globalObject); |
| bool hasOwnProperty = globalObject->getOwnPropertySlot(globalObject, exec, ident, slot); |
| if (!hasOwnProperty) { |
| op = ResolveOp(makeType(UnresolvedProperty, needsVarInjectionChecks), 0, 0, 0, 0, 0); |
| return true; |
| } |
| |
| if (!slot.isCacheableValue() |
| || !globalObject->structure()->propertyAccessesAreCacheable() |
| || (globalObject->structure()->hasReadOnlyOrGetterSetterPropertiesExcludingProto() && getOrPut == Put)) { |
| // We know the property will be at global scope, but we don't know how to cache it. |
| ASSERT(!scope->next()); |
| op = ResolveOp(makeType(GlobalProperty, needsVarInjectionChecks), 0, 0, 0, 0, 0); |
| return true; |
| } |
| |
| |
| WatchpointState state = globalObject->structure()->ensurePropertyReplacementWatchpointSet(exec->vm(), slot.cachedOffset())->state(); |
| if (state == IsWatched && getOrPut == Put) { |
| // The field exists, but because the replacement watchpoint is still intact. This is |
| // kind of dangerous. We have two options: |
| // 1) Invalidate the watchpoint set. That would work, but it's possible that this code |
| // path never executes - in which case this would be unwise. |
| // 2) Have the invalidation happen at run-time. All we have to do is leave the code |
| // uncached. The only downside is slightly more work when this does execute. |
| // We go with option (2) here because it seems less evil. |
| op = ResolveOp(makeType(GlobalProperty, needsVarInjectionChecks), depth, 0, 0, 0, 0); |
| } else |
| op = ResolveOp(makeType(GlobalProperty, needsVarInjectionChecks), depth, globalObject->structure(), 0, 0, slot.cachedOffset()); |
| return true; |
| } |
| |
| op = ResolveOp(Dynamic, 0, 0, 0, 0, 0); |
| return true; |
| } |
| |
| JSObject* JSScope::objectAtScope(JSScope* scope) |
| { |
| JSObject* object = scope; |
| if (object->type() == WithScopeType) |
| return jsCast<JSWithScope*>(object)->object(); |
| |
| return object; |
| } |
| |
| // When an exception occurs, the result of isUnscopable becomes false. |
| static inline bool isUnscopable(ExecState* exec, JSScope* scope, JSObject* object, const Identifier& ident) |
| { |
| if (scope->type() != WithScopeType) |
| return false; |
| |
| JSValue unscopables = object->get(exec, exec->propertyNames().unscopablesSymbol); |
| if (exec->hadException()) |
| return false; |
| if (!unscopables.isObject()) |
| return false; |
| JSValue blocked = jsCast<JSObject*>(unscopables)->get(exec, ident); |
| if (exec->hadException()) |
| return false; |
| |
| return blocked.toBoolean(exec); |
| } |
| |
| JSValue JSScope::resolve(ExecState* exec, JSScope* scope, const Identifier& ident) |
| { |
| ScopeChainIterator end = scope->end(); |
| ScopeChainIterator it = scope->begin(); |
| while (1) { |
| JSScope* scope = it.scope(); |
| JSObject* object = it.get(); |
| |
| if (++it == end) // Global scope. |
| return object; |
| |
| if (object->hasProperty(exec, ident)) { |
| if (!isUnscopable(exec, scope, object, ident)) |
| return object; |
| ASSERT_WITH_MESSAGE(!exec->hadException(), "When an exception occurs, the result of isUnscopable becomes false"); |
| } |
| } |
| } |
| |
| ResolveOp JSScope::abstractResolve(ExecState* exec, size_t depthOffset, JSScope* scope, const Identifier& ident, GetOrPut getOrPut, ResolveType unlinkedType, InitializationMode initializationMode) |
| { |
| ResolveOp op(Dynamic, 0, 0, 0, 0, 0); |
| if (unlinkedType == Dynamic) |
| return op; |
| |
| bool needsVarInjectionChecks = JSC::needsVarInjectionChecks(unlinkedType); |
| size_t depth = depthOffset; |
| for (; scope; scope = scope->next()) { |
| if (abstractAccess(exec, scope, ident, getOrPut, depth, needsVarInjectionChecks, op, initializationMode)) |
| break; |
| ++depth; |
| } |
| |
| return op; |
| } |
| |
| void JSScope::collectVariablesUnderTDZ(JSScope* scope, VariableEnvironment& result) |
| { |
| for (; scope; scope = scope->next()) { |
| if (!scope->isLexicalScope() && !scope->isGlobalLexicalEnvironment()) |
| continue; |
| |
| if (scope->isModuleScope()) { |
| JSModuleRecord* moduleRecord = jsCast<JSModuleEnvironment*>(scope)->moduleRecord(); |
| for (const auto& pair : moduleRecord->importEntries()) |
| result.add(pair.key); |
| } |
| |
| SymbolTable* symbolTable = jsCast<JSSymbolTableObject*>(scope)->symbolTable(); |
| ASSERT(symbolTable->scopeType() == SymbolTable::ScopeType::LexicalScope || symbolTable->scopeType() == SymbolTable::ScopeType::GlobalLexicalScope); |
| ConcurrentJITLocker locker(symbolTable->m_lock); |
| for (auto end = symbolTable->end(locker), iter = symbolTable->begin(locker); iter != end; ++iter) |
| result.add(iter->key); |
| } |
| } |
| |
| template <typename EnvironmentType, SymbolTable::ScopeType scopeType> |
| inline static bool isScopeType(JSScope* scope) |
| { |
| EnvironmentType* environment = jsDynamicCast<EnvironmentType*>(scope); |
| if (!environment) |
| return false; |
| |
| return environment->symbolTable()->scopeType() == scopeType; |
| } |
| |
| bool JSScope::isVarScope() |
| { |
| return isScopeType<JSLexicalEnvironment, SymbolTable::ScopeType::VarScope>(this); |
| } |
| |
| bool JSScope::isLexicalScope() |
| { |
| return isScopeType<JSLexicalEnvironment, SymbolTable::ScopeType::LexicalScope>(this); |
| } |
| |
| bool JSScope::isModuleScope() |
| { |
| return isScopeType<JSModuleEnvironment, SymbolTable::ScopeType::LexicalScope>(this); |
| } |
| |
| bool JSScope::isCatchScope() |
| { |
| return isScopeType<JSLexicalEnvironment, SymbolTable::ScopeType::CatchScope>(this); |
| } |
| |
| bool JSScope::isFunctionNameScopeObject() |
| { |
| return isScopeType<JSLexicalEnvironment, SymbolTable::ScopeType::FunctionNameScope>(this); |
| } |
| |
| bool JSScope::isGlobalLexicalEnvironment() |
| { |
| return isScopeType<JSGlobalLexicalEnvironment, SymbolTable::ScopeType::GlobalLexicalScope>(this); |
| } |
| |
| bool JSScope::isNestedLexicalScope() |
| { |
| if (JSLexicalEnvironment* environment = jsDynamicCast<JSLexicalEnvironment*>(this)) |
| return environment->symbolTable()->isNestedLexicalScope(); |
| return false; |
| } |
| |
| JSScope* JSScope::constantScopeForCodeBlock(ResolveType type, CodeBlock* codeBlock) |
| { |
| switch (type) { |
| case GlobalProperty: |
| case GlobalVar: |
| case GlobalPropertyWithVarInjectionChecks: |
| case GlobalVarWithVarInjectionChecks: |
| return codeBlock->globalObject(); |
| case GlobalLexicalVarWithVarInjectionChecks: |
| case GlobalLexicalVar: |
| return codeBlock->globalObject()->globalLexicalEnvironment(); |
| default: |
| return nullptr; |
| } |
| |
| RELEASE_ASSERT_NOT_REACHED(); |
| return nullptr; |
| } |
| |
| } // namespace JSC |
