| /* |
| * 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 "JSNameScope.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) |
| { |
| 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 (lexicalEnvironment->symbolTable()->usesNonStrictEval()) |
| needsVarInjectionChecks = 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); |
| if (!globalObject->getOwnPropertySlot(globalObject, exec, ident, slot) |
| || !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), depth, 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; |
| } |
| |
| int JSScope::depth() |
| { |
| int depth = 0; |
| for (JSScope* scope = this; scope; scope = scope->next()) |
| ++depth; |
| return depth; |
| } |
| |
| // 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, bool hasTopActivation, JSScope* scope, const Identifier& ident, GetOrPut getOrPut, ResolveType unlinkedType) |
| { |
| ResolveOp op(Dynamic, 0, 0, 0, 0, 0); |
| if (unlinkedType == Dynamic) |
| return op; |
| |
| size_t depth = hasTopActivation ? 1 : 0; |
| bool needsVarInjectionChecks = JSC::needsVarInjectionChecks(unlinkedType); |
| for (; scope; scope = scope->next()) { |
| if (abstractAccess(exec, scope, ident, getOrPut, depth, needsVarInjectionChecks, op)) |
| break; |
| ++depth; |
| } |
| |
| return op; |
| } |
| |
| const char* resolveModeName(ResolveMode mode) |
| { |
| static const char* const names[] = { |
| "ThrowIfNotFound", |
| "DoNotThrowIfNotFound" |
| }; |
| return names[mode]; |
| } |
| |
| const char* resolveTypeName(ResolveType type) |
| { |
| static const char* const names[] = { |
| "GlobalProperty", |
| "GlobalVar", |
| "ClosureVar", |
| "LocalClosureVar", |
| "GlobalPropertyWithVarInjectionChecks", |
| "GlobalVarWithVarInjectionChecks", |
| "ClosureVarWithVarInjectionChecks", |
| "Dynamic" |
| }; |
| return names[type]; |
| } |
| |
| } // namespace JSC |
