diff options
Diffstat (limited to 'V8Binding/v8/src/scopes.cc')
| -rw-r--r-- | V8Binding/v8/src/scopes.cc | 962 |
1 files changed, 0 insertions, 962 deletions
diff --git a/V8Binding/v8/src/scopes.cc b/V8Binding/v8/src/scopes.cc deleted file mode 100644 index 25873fa..0000000 --- a/V8Binding/v8/src/scopes.cc +++ /dev/null @@ -1,962 +0,0 @@ -// Copyright 2006-2008 the V8 project authors. All rights reserved. -// Redistribution and use in source and binary forms, with or without -// modification, are permitted provided that the following conditions are -// met: -// -// * Redistributions of source code must retain the above copyright -// notice, this list of conditions and the following disclaimer. -// * 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. -// * Neither the name of Google Inc. nor the names of its -// contributors may be used to endorse or promote products derived -// from this software without specific prior written permission. -// -// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS -// "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 THE COPYRIGHT -// OWNER 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 "v8.h" - -#include "prettyprinter.h" -#include "scopeinfo.h" -#include "scopes.h" - -namespace v8 { -namespace internal { - -// ---------------------------------------------------------------------------- -// A Zone allocator for use with LocalsMap. - -class ZoneAllocator: public Allocator { - public: - /* nothing to do */ - virtual ~ZoneAllocator() {} - - virtual void* New(size_t size) { return Zone::New(size); } - - /* ignored - Zone is freed in one fell swoop */ - virtual void Delete(void* p) {} -}; - - -static ZoneAllocator LocalsMapAllocator; - - -// ---------------------------------------------------------------------------- -// Implementation of LocalsMap -// -// Note: We are storing the handle locations as key values in the hash map. -// When inserting a new variable via Declare(), we rely on the fact that -// the handle location remains alive for the duration of that variable -// use. Because a Variable holding a handle with the same location exists -// this is ensured. - -static bool Match(void* key1, void* key2) { - String* name1 = *reinterpret_cast<String**>(key1); - String* name2 = *reinterpret_cast<String**>(key2); - ASSERT(name1->IsSymbol()); - ASSERT(name2->IsSymbol()); - return name1 == name2; -} - - -// Dummy constructor -VariableMap::VariableMap(bool gotta_love_static_overloading) : HashMap() {} - -VariableMap::VariableMap() : HashMap(Match, &LocalsMapAllocator, 8) {} -VariableMap::~VariableMap() {} - - -Variable* VariableMap::Declare(Scope* scope, - Handle<String> name, - Variable::Mode mode, - bool is_valid_lhs, - Variable::Kind kind) { - HashMap::Entry* p = HashMap::Lookup(name.location(), name->Hash(), true); - if (p->value == NULL) { - // The variable has not been declared yet -> insert it. - ASSERT(p->key == name.location()); - p->value = new Variable(scope, name, mode, is_valid_lhs, kind); - } - return reinterpret_cast<Variable*>(p->value); -} - - -Variable* VariableMap::Lookup(Handle<String> name) { - HashMap::Entry* p = HashMap::Lookup(name.location(), name->Hash(), false); - if (p != NULL) { - ASSERT(*reinterpret_cast<String**>(p->key) == *name); - ASSERT(p->value != NULL); - return reinterpret_cast<Variable*>(p->value); - } - return NULL; -} - - -// ---------------------------------------------------------------------------- -// Implementation of Scope - - -// Dummy constructor -Scope::Scope(Type type) - : outer_scope_(NULL), - inner_scopes_(0), - type_(type), - scope_name_(Factory::empty_symbol()), - variables_(false), - temps_(0), - params_(0), - dynamics_(NULL), - unresolved_(0), - decls_(0), - receiver_(NULL), - function_(NULL), - arguments_(NULL), - arguments_shadow_(NULL), - illegal_redecl_(NULL), - scope_inside_with_(false), - scope_contains_with_(false), - scope_calls_eval_(false), - outer_scope_calls_eval_(false), - inner_scope_calls_eval_(false), - outer_scope_is_eval_scope_(false), - force_eager_compilation_(false), - num_stack_slots_(0), - num_heap_slots_(0) { -} - - -Scope::Scope(Scope* outer_scope, Type type) - : outer_scope_(outer_scope), - inner_scopes_(4), - type_(type), - scope_name_(Factory::empty_symbol()), - temps_(4), - params_(4), - dynamics_(NULL), - unresolved_(16), - decls_(4), - receiver_(NULL), - function_(NULL), - arguments_(NULL), - arguments_shadow_(NULL), - illegal_redecl_(NULL), - scope_inside_with_(false), - scope_contains_with_(false), - scope_calls_eval_(false), - outer_scope_calls_eval_(false), - inner_scope_calls_eval_(false), - outer_scope_is_eval_scope_(false), - force_eager_compilation_(false), - num_stack_slots_(0), - num_heap_slots_(0) { - // At some point we might want to provide outer scopes to - // eval scopes (by walking the stack and reading the scope info). - // In that case, the ASSERT below needs to be adjusted. - ASSERT((type == GLOBAL_SCOPE || type == EVAL_SCOPE) == (outer_scope == NULL)); - ASSERT(!HasIllegalRedeclaration()); -} - - -void Scope::Initialize(bool inside_with) { - // Add this scope as a new inner scope of the outer scope. - if (outer_scope_ != NULL) { - outer_scope_->inner_scopes_.Add(this); - scope_inside_with_ = outer_scope_->scope_inside_with_ || inside_with; - } else { - scope_inside_with_ = inside_with; - } - - // Declare convenience variables. - // Declare and allocate receiver (even for the global scope, and even - // if naccesses_ == 0). - // NOTE: When loading parameters in the global scope, we must take - // care not to access them as properties of the global object, but - // instead load them directly from the stack. Currently, the only - // such parameter is 'this' which is passed on the stack when - // invoking scripts - Variable* var = - variables_.Declare(this, Factory::this_symbol(), Variable::VAR, - false, Variable::THIS); - var->rewrite_ = new Slot(var, Slot::PARAMETER, -1); - receiver_ = new VariableProxy(Factory::this_symbol(), true, false); - receiver_->BindTo(var); - - if (is_function_scope()) { - // Declare 'arguments' variable which exists in all functions. - // Note that it might never be accessed, in which case it won't be - // allocated during variable allocation. - variables_.Declare(this, Factory::arguments_symbol(), Variable::VAR, - true, Variable::ARGUMENTS); - } -} - - - -Variable* Scope::LocalLookup(Handle<String> name) { - return variables_.Lookup(name); -} - - -Variable* Scope::Lookup(Handle<String> name) { - for (Scope* scope = this; - scope != NULL; - scope = scope->outer_scope()) { - Variable* var = scope->LocalLookup(name); - if (var != NULL) return var; - } - return NULL; -} - - -Variable* Scope::DeclareFunctionVar(Handle<String> name) { - ASSERT(is_function_scope() && function_ == NULL); - function_ = new Variable(this, name, Variable::CONST, true, Variable::NORMAL); - return function_; -} - - -Variable* Scope::DeclareLocal(Handle<String> name, Variable::Mode mode) { - // DYNAMIC variables are introduces during variable allocation, - // INTERNAL variables are allocated explicitly, and TEMPORARY - // variables are allocated via NewTemporary(). - ASSERT(mode == Variable::VAR || mode == Variable::CONST); - return variables_.Declare(this, name, mode, true, Variable::NORMAL); -} - - -Variable* Scope::DeclareGlobal(Handle<String> name) { - ASSERT(is_global_scope()); - return variables_.Declare(this, name, Variable::DYNAMIC, true, - Variable::NORMAL); -} - - -void Scope::AddParameter(Variable* var) { - ASSERT(is_function_scope()); - ASSERT(LocalLookup(var->name()) == var); - params_.Add(var); -} - - -VariableProxy* Scope::NewUnresolved(Handle<String> name, bool inside_with) { - // Note that we must not share the unresolved variables with - // the same name because they may be removed selectively via - // RemoveUnresolved(). - VariableProxy* proxy = new VariableProxy(name, false, inside_with); - unresolved_.Add(proxy); - return proxy; -} - - -void Scope::RemoveUnresolved(VariableProxy* var) { - // Most likely (always?) any variable we want to remove - // was just added before, so we search backwards. - for (int i = unresolved_.length(); i-- > 0;) { - if (unresolved_[i] == var) { - unresolved_.Remove(i); - return; - } - } -} - - -VariableProxy* Scope::NewTemporary(Handle<String> name) { - Variable* var = new Variable(this, name, Variable::TEMPORARY, true, - Variable::NORMAL); - VariableProxy* tmp = new VariableProxy(name, false, false); - tmp->BindTo(var); - temps_.Add(var); - return tmp; -} - - -void Scope::AddDeclaration(Declaration* declaration) { - decls_.Add(declaration); -} - - -void Scope::SetIllegalRedeclaration(Expression* expression) { - // Only set the illegal redeclaration expression the - // first time the function is called. - if (!HasIllegalRedeclaration()) { - illegal_redecl_ = expression; - } - ASSERT(HasIllegalRedeclaration()); -} - - -void Scope::VisitIllegalRedeclaration(AstVisitor* visitor) { - ASSERT(HasIllegalRedeclaration()); - illegal_redecl_->Accept(visitor); -} - - -template<class Allocator> -void Scope::CollectUsedVariables(List<Variable*, Allocator>* locals) { - // Collect variables in this scope. - // Note that the function_ variable - if present - is not - // collected here but handled separately in ScopeInfo - // which is the current user of this function). - for (int i = 0; i < temps_.length(); i++) { - Variable* var = temps_[i]; - if (var->var_uses()->is_used()) { - locals->Add(var); - } - } - for (VariableMap::Entry* p = variables_.Start(); - p != NULL; - p = variables_.Next(p)) { - Variable* var = reinterpret_cast<Variable*>(p->value); - if (var->var_uses()->is_used()) { - locals->Add(var); - } - } -} - - -// Make sure the method gets instantiated by the template system. -template void Scope::CollectUsedVariables( - List<Variable*, FreeStoreAllocationPolicy>* locals); -template void Scope::CollectUsedVariables( - List<Variable*, PreallocatedStorage>* locals); -template void Scope::CollectUsedVariables( - List<Variable*, ZoneListAllocationPolicy>* locals); - - -void Scope::AllocateVariables(Handle<Context> context) { - ASSERT(outer_scope_ == NULL); // eval or global scopes only - - // 1) Propagate scope information. - // If we are in an eval scope, we may have other outer scopes about - // which we don't know anything at this point. Thus we must be conservative - // and assume they may invoke eval themselves. Eventually we could capture - // this information in the ScopeInfo and then use it here (by traversing - // the call chain stack, at compile time). - bool eval_scope = is_eval_scope(); - PropagateScopeInfo(eval_scope, eval_scope); - - // 2) Resolve variables. - Scope* global_scope = NULL; - if (is_global_scope()) global_scope = this; - ResolveVariablesRecursively(global_scope, context); - - // 3) Allocate variables. - AllocateVariablesRecursively(); -} - - -bool Scope::AllowsLazyCompilation() const { - return !force_eager_compilation_ && HasTrivialOuterContext(); -} - - -bool Scope::HasTrivialContext() const { - // A function scope has a trivial context if it always is the global - // context. We iteratively scan out the context chain to see if - // there is anything that makes this scope non-trivial; otherwise we - // return true. - for (const Scope* scope = this; scope != NULL; scope = scope->outer_scope_) { - if (scope->is_eval_scope()) return false; - if (scope->scope_inside_with_) return false; - if (scope->num_heap_slots_ > 0) return false; - } - return true; -} - - -bool Scope::HasTrivialOuterContext() const { - Scope* outer = outer_scope_; - if (outer == NULL) return true; - // Note that the outer context may be trivial in general, but the current - // scope may be inside a 'with' statement in which case the outer context - // for this scope is not trivial. - return !scope_inside_with_ && outer->HasTrivialContext(); -} - - -int Scope::ContextChainLength(Scope* scope) { - int n = 0; - for (Scope* s = this; s != scope; s = s->outer_scope_) { - ASSERT(s != NULL); // scope must be in the scope chain - if (s->num_heap_slots() > 0) n++; - } - return n; -} - - -#ifdef DEBUG -static const char* Header(Scope::Type type) { - switch (type) { - case Scope::EVAL_SCOPE: return "eval"; - case Scope::FUNCTION_SCOPE: return "function"; - case Scope::GLOBAL_SCOPE: return "global"; - } - UNREACHABLE(); - return NULL; -} - - -static void Indent(int n, const char* str) { - PrintF("%*s%s", n, "", str); -} - - -static void PrintName(Handle<String> name) { - SmartPointer<char> s = name->ToCString(DISALLOW_NULLS); - PrintF("%s", *s); -} - - -static void PrintVar(PrettyPrinter* printer, int indent, Variable* var) { - if (var->var_uses()->is_used() || var->rewrite() != NULL) { - Indent(indent, Variable::Mode2String(var->mode())); - PrintF(" "); - PrintName(var->name()); - PrintF("; // "); - if (var->rewrite() != NULL) PrintF("%s, ", printer->Print(var->rewrite())); - if (var->is_accessed_from_inner_scope()) PrintF("inner scope access, "); - PrintF("var "); - var->var_uses()->Print(); - PrintF(", obj "); - var->obj_uses()->Print(); - PrintF("\n"); - } -} - - -static void PrintMap(PrettyPrinter* printer, int indent, VariableMap* map) { - for (VariableMap::Entry* p = map->Start(); p != NULL; p = map->Next(p)) { - Variable* var = reinterpret_cast<Variable*>(p->value); - PrintVar(printer, indent, var); - } -} - - -void Scope::Print(int n) { - int n0 = (n > 0 ? n : 0); - int n1 = n0 + 2; // indentation - - // Print header. - Indent(n0, Header(type_)); - if (scope_name_->length() > 0) { - PrintF(" "); - PrintName(scope_name_); - } - - // Print parameters, if any. - if (is_function_scope()) { - PrintF(" ("); - for (int i = 0; i < params_.length(); i++) { - if (i > 0) PrintF(", "); - PrintName(params_[i]->name()); - } - PrintF(")"); - } - - PrintF(" {\n"); - - // Function name, if any (named function literals, only). - if (function_ != NULL) { - Indent(n1, "// (local) function name: "); - PrintName(function_->name()); - PrintF("\n"); - } - - // Scope info. - if (HasTrivialOuterContext()) { - Indent(n1, "// scope has trivial outer context\n"); - } - if (scope_inside_with_) Indent(n1, "// scope inside 'with'\n"); - if (scope_contains_with_) Indent(n1, "// scope contains 'with'\n"); - if (scope_calls_eval_) Indent(n1, "// scope calls 'eval'\n"); - if (outer_scope_calls_eval_) Indent(n1, "// outer scope calls 'eval'\n"); - if (inner_scope_calls_eval_) Indent(n1, "// inner scope calls 'eval'\n"); - if (outer_scope_is_eval_scope_) { - Indent(n1, "// outer scope is 'eval' scope\n"); - } - if (num_stack_slots_ > 0) { Indent(n1, "// "); - PrintF("%d stack slots\n", num_stack_slots_); } - if (num_heap_slots_ > 0) { Indent(n1, "// "); - PrintF("%d heap slots\n", num_heap_slots_); } - - // Print locals. - PrettyPrinter printer; - Indent(n1, "// function var\n"); - if (function_ != NULL) { - PrintVar(&printer, n1, function_); - } - - Indent(n1, "// temporary vars\n"); - for (int i = 0; i < temps_.length(); i++) { - PrintVar(&printer, n1, temps_[i]); - } - - Indent(n1, "// local vars\n"); - PrintMap(&printer, n1, &variables_); - - Indent(n1, "// dynamic vars\n"); - if (dynamics_ != NULL) { - PrintMap(&printer, n1, dynamics_->GetMap(Variable::DYNAMIC)); - PrintMap(&printer, n1, dynamics_->GetMap(Variable::DYNAMIC_LOCAL)); - PrintMap(&printer, n1, dynamics_->GetMap(Variable::DYNAMIC_GLOBAL)); - } - - // Print inner scopes (disable by providing negative n). - if (n >= 0) { - for (int i = 0; i < inner_scopes_.length(); i++) { - PrintF("\n"); - inner_scopes_[i]->Print(n1); - } - } - - Indent(n0, "}\n"); -} -#endif // DEBUG - - -Variable* Scope::NonLocal(Handle<String> name, Variable::Mode mode) { - if (dynamics_ == NULL) dynamics_ = new DynamicScopePart(); - VariableMap* map = dynamics_->GetMap(mode); - Variable* var = map->Lookup(name); - if (var == NULL) { - // Declare a new non-local. - var = map->Declare(NULL, name, mode, true, Variable::NORMAL); - // Allocate it by giving it a dynamic lookup. - var->rewrite_ = new Slot(var, Slot::LOOKUP, -1); - } - return var; -} - - -// Lookup a variable starting with this scope. The result is either -// the statically resolved (local!) variable belonging to an outer scope, -// or NULL. It may be NULL because a) we couldn't find a variable, or b) -// because the variable is just a guess (and may be shadowed by another -// variable that is introduced dynamically via an 'eval' call or a 'with' -// statement). -Variable* Scope::LookupRecursive(Handle<String> name, - bool inner_lookup, - Variable** invalidated_local) { - // If we find a variable, but the current scope calls 'eval', the found - // variable may not be the correct one (the 'eval' may introduce a - // property with the same name). In that case, remember that the variable - // found is just a guess. - bool guess = scope_calls_eval_; - - // Try to find the variable in this scope. - Variable* var = LocalLookup(name); - - if (var != NULL) { - // We found a variable. If this is not an inner lookup, we are done. - // (Even if there is an 'eval' in this scope which introduces the - // same variable again, the resulting variable remains the same. - // Note that enclosing 'with' statements are handled at the call site.) - if (!inner_lookup) - return var; - - } else { - // We did not find a variable locally. Check against the function variable, - // if any. We can do this for all scopes, since the function variable is - // only present - if at all - for function scopes. - // - // This lookup corresponds to a lookup in the "intermediate" scope sitting - // between this scope and the outer scope. (ECMA-262, 3rd., requires that - // the name of named function literal is kept in an intermediate scope - // in between this scope and the next outer scope.) - if (function_ != NULL && function_->name().is_identical_to(name)) { - var = function_; - - } else if (outer_scope_ != NULL) { - var = outer_scope_->LookupRecursive(name, true, invalidated_local); - // We may have found a variable in an outer scope. However, if - // the current scope is inside a 'with', the actual variable may - // be a property introduced via the 'with' statement. Then, the - // variable we may have found is just a guess. - if (scope_inside_with_) - guess = true; - } - - // If we did not find a variable, we are done. - if (var == NULL) - return NULL; - } - - ASSERT(var != NULL); - - // If this is a lookup from an inner scope, mark the variable. - if (inner_lookup) - var->is_accessed_from_inner_scope_ = true; - - // If the variable we have found is just a guess, invalidate the result. - if (guess) { - *invalidated_local = var; - var = NULL; - } - - return var; -} - - -void Scope::ResolveVariable(Scope* global_scope, - Handle<Context> context, - VariableProxy* proxy) { - ASSERT(global_scope == NULL || global_scope->is_global_scope()); - - // If the proxy is already resolved there's nothing to do - // (functions and consts may be resolved by the parser). - if (proxy->var() != NULL) return; - - // Otherwise, try to resolve the variable. - Variable* invalidated_local = NULL; - Variable* var = LookupRecursive(proxy->name(), false, &invalidated_local); - - if (proxy->inside_with()) { - // If we are inside a local 'with' statement, all bets are off - // and we cannot resolve the proxy to a local variable even if - // we found an outer matching variable. - // Note that we must do a lookup anyway, because if we find one, - // we must mark that variable as potentially accessed from this - // inner scope (the property may not be in the 'with' object). - var = NonLocal(proxy->name(), Variable::DYNAMIC); - - } else { - // We are not inside a local 'with' statement. - - if (var == NULL) { - // We did not find the variable. We have a global variable - // if we are in the global scope (we know already that we - // are outside a 'with' statement) or if there is no way - // that the variable might be introduced dynamically (through - // a local or outer eval() call, or an outer 'with' statement), - // or we don't know about the outer scope (because we are - // in an eval scope). - if (is_global_scope() || - !(scope_inside_with_ || outer_scope_is_eval_scope_ || - scope_calls_eval_ || outer_scope_calls_eval_)) { - // We must have a global variable. - ASSERT(global_scope != NULL); - var = global_scope->DeclareGlobal(proxy->name()); - - } else if (scope_inside_with_) { - // If we are inside a with statement we give up and look up - // the variable at runtime. - var = NonLocal(proxy->name(), Variable::DYNAMIC); - - } else if (invalidated_local != NULL) { - // No with statements are involved and we found a local - // variable that might be shadowed by eval introduced - // variables. - var = NonLocal(proxy->name(), Variable::DYNAMIC_LOCAL); - var->set_local_if_not_shadowed(invalidated_local); - - } else if (outer_scope_is_eval_scope_) { - // No with statements and we did not find a local and the code - // is executed with a call to eval. The context contains - // scope information that we can use to determine if the - // variable is global if it is not shadowed by eval-introduced - // variables. - if (context->GlobalIfNotShadowedByEval(proxy->name())) { - var = NonLocal(proxy->name(), Variable::DYNAMIC_GLOBAL); - - } else { - var = NonLocal(proxy->name(), Variable::DYNAMIC); - } - - } else { - // No with statements and we did not find a local and the code - // is not executed with a call to eval. We know that this - // variable is global unless it is shadowed by eval-introduced - // variables. - var = NonLocal(proxy->name(), Variable::DYNAMIC_GLOBAL); - } - } - } - - proxy->BindTo(var); -} - - -void Scope::ResolveVariablesRecursively(Scope* global_scope, - Handle<Context> context) { - ASSERT(global_scope == NULL || global_scope->is_global_scope()); - - // Resolve unresolved variables for this scope. - for (int i = 0; i < unresolved_.length(); i++) { - ResolveVariable(global_scope, context, unresolved_[i]); - } - - // Resolve unresolved variables for inner scopes. - for (int i = 0; i < inner_scopes_.length(); i++) { - inner_scopes_[i]->ResolveVariablesRecursively(global_scope, context); - } -} - - -bool Scope::PropagateScopeInfo(bool outer_scope_calls_eval, - bool outer_scope_is_eval_scope) { - if (outer_scope_calls_eval) { - outer_scope_calls_eval_ = true; - } - - if (outer_scope_is_eval_scope) { - outer_scope_is_eval_scope_ = true; - } - - bool calls_eval = scope_calls_eval_ || outer_scope_calls_eval_; - bool is_eval = is_eval_scope() || outer_scope_is_eval_scope_; - for (int i = 0; i < inner_scopes_.length(); i++) { - Scope* inner_scope = inner_scopes_[i]; - if (inner_scope->PropagateScopeInfo(calls_eval, is_eval)) { - inner_scope_calls_eval_ = true; - } - if (inner_scope->force_eager_compilation_) { - force_eager_compilation_ = true; - } - } - - return scope_calls_eval_ || inner_scope_calls_eval_; -} - - -bool Scope::MustAllocate(Variable* var) { - // Give var a read/write use if there is a chance it might be accessed - // via an eval() call. This is only possible if the variable has a - // visible name. - if ((var->is_this() || var->name()->length() > 0) && - (var->is_accessed_from_inner_scope_ || - scope_calls_eval_ || inner_scope_calls_eval_ || - scope_contains_with_)) { - var->var_uses()->RecordAccess(1); - } - // Global variables do not need to be allocated. - return !var->is_global() && var->var_uses()->is_used(); -} - - -bool Scope::MustAllocateInContext(Variable* var) { - // If var is accessed from an inner scope, or if there is a - // possibility that it might be accessed from the current or an inner - // scope (through an eval() call), it must be allocated in the - // context. Exception: temporary variables are not allocated in the - // context. - return - var->mode() != Variable::TEMPORARY && - (var->is_accessed_from_inner_scope_ || - scope_calls_eval_ || inner_scope_calls_eval_ || - scope_contains_with_ || var->is_global()); -} - - -bool Scope::HasArgumentsParameter() { - for (int i = 0; i < params_.length(); i++) { - if (params_[i]->name().is_identical_to(Factory::arguments_symbol())) - return true; - } - return false; -} - - -void Scope::AllocateStackSlot(Variable* var) { - var->rewrite_ = new Slot(var, Slot::LOCAL, num_stack_slots_++); -} - - -void Scope::AllocateHeapSlot(Variable* var) { - var->rewrite_ = new Slot(var, Slot::CONTEXT, num_heap_slots_++); -} - - -void Scope::AllocateParameterLocals() { - ASSERT(is_function_scope()); - Variable* arguments = LocalLookup(Factory::arguments_symbol()); - ASSERT(arguments != NULL); // functions have 'arguments' declared implicitly - if (MustAllocate(arguments) && !HasArgumentsParameter()) { - // 'arguments' is used. Unless there is also a parameter called - // 'arguments', we must be conservative and access all parameters via - // the arguments object: The i'th parameter is rewritten into - // '.arguments[i]' (*). If we have a parameter named 'arguments', a - // (new) value is always assigned to it via the function - // invocation. Then 'arguments' denotes that specific parameter value - // and cannot be used to access the parameters, which is why we don't - // need to rewrite in that case. - // - // (*) Instead of having a parameter called 'arguments', we may have an - // assignment to 'arguments' in the function body, at some arbitrary - // point in time (possibly through an 'eval()' call!). After that - // assignment any re-write of parameters would be invalid (was bug - // 881452). Thus, we introduce a shadow '.arguments' - // variable which also points to the arguments object. For rewrites we - // use '.arguments' which remains valid even if we assign to - // 'arguments'. To summarize: If we need to rewrite, we allocate an - // 'arguments' object dynamically upon function invocation. The compiler - // introduces 2 local variables 'arguments' and '.arguments', both of - // which originally point to the arguments object that was - // allocated. All parameters are rewritten into property accesses via - // the '.arguments' variable. Thus, any changes to properties of - // 'arguments' are reflected in the variables and vice versa. If the - // 'arguments' variable is changed, '.arguments' still points to the - // correct arguments object and the rewrites still work. - - // We are using 'arguments'. Tell the code generator that is needs to - // allocate the arguments object by setting 'arguments_'. - arguments_ = new VariableProxy(Factory::arguments_symbol(), false, false); - arguments_->BindTo(arguments); - - // We also need the '.arguments' shadow variable. Declare it and create - // and bind the corresponding proxy. It's ok to declare it only now - // because it's a local variable that is allocated after the parameters - // have been allocated. - // - // Note: This is "almost" at temporary variable but we cannot use - // NewTemporary() because the mode needs to be INTERNAL since this - // variable may be allocated in the heap-allocated context (temporaries - // are never allocated in the context). - Variable* arguments_shadow = - new Variable(this, Factory::arguments_shadow_symbol(), - Variable::INTERNAL, true, Variable::ARGUMENTS); - arguments_shadow_ = - new VariableProxy(Factory::arguments_shadow_symbol(), false, false); - arguments_shadow_->BindTo(arguments_shadow); - temps_.Add(arguments_shadow); - - // Allocate the parameters by rewriting them into '.arguments[i]' accesses. - for (int i = 0; i < params_.length(); i++) { - Variable* var = params_[i]; - ASSERT(var->scope() == this); - if (MustAllocate(var)) { - if (MustAllocateInContext(var)) { - // It is ok to set this only now, because arguments is a local - // variable that is allocated after the parameters have been - // allocated. - arguments_shadow->is_accessed_from_inner_scope_ = true; - } - var->rewrite_ = - new Property(arguments_shadow_, - new Literal(Handle<Object>(Smi::FromInt(i))), - RelocInfo::kNoPosition, - Property::SYNTHETIC); - arguments_shadow->var_uses()->RecordUses(var->var_uses()); - } - } - - } else { - // The arguments object is not used, so we can access parameters directly. - // The same parameter may occur multiple times in the parameters_ list. - // If it does, and if it is not copied into the context object, it must - // receive the highest parameter index for that parameter; thus iteration - // order is relevant! - for (int i = 0; i < params_.length(); i++) { - Variable* var = params_[i]; - ASSERT(var->scope() == this); - if (MustAllocate(var)) { - if (MustAllocateInContext(var)) { - ASSERT(var->rewrite_ == NULL || - (var->slot() != NULL && var->slot()->type() == Slot::CONTEXT)); - if (var->rewrite_ == NULL) { - // Only set the heap allocation if the parameter has not - // been allocated yet. - AllocateHeapSlot(var); - } - } else { - ASSERT(var->rewrite_ == NULL || - (var->slot() != NULL && - var->slot()->type() == Slot::PARAMETER)); - // Set the parameter index always, even if the parameter - // was seen before! (We need to access the actual parameter - // supplied for the last occurrence of a multiply declared - // parameter.) - var->rewrite_ = new Slot(var, Slot::PARAMETER, i); - } - } - } - } -} - - -void Scope::AllocateNonParameterLocal(Variable* var) { - ASSERT(var->scope() == this); - ASSERT(var->rewrite_ == NULL || - (!var->IsVariable(Factory::result_symbol())) || - (var->slot() == NULL || var->slot()->type() != Slot::LOCAL)); - if (var->rewrite_ == NULL && MustAllocate(var)) { - if (MustAllocateInContext(var)) { - AllocateHeapSlot(var); - } else { - AllocateStackSlot(var); - } - } -} - - -void Scope::AllocateNonParameterLocals() { - // All variables that have no rewrite yet are non-parameter locals. - for (int i = 0; i < temps_.length(); i++) { - AllocateNonParameterLocal(temps_[i]); - } - - for (VariableMap::Entry* p = variables_.Start(); - p != NULL; - p = variables_.Next(p)) { - Variable* var = reinterpret_cast<Variable*>(p->value); - AllocateNonParameterLocal(var); - } - - // For now, function_ must be allocated at the very end. If it gets - // allocated in the context, it must be the last slot in the context, - // because of the current ScopeInfo implementation (see - // ScopeInfo::ScopeInfo(FunctionScope* scope) constructor). - if (function_ != NULL) { - AllocateNonParameterLocal(function_); - } -} - - -void Scope::AllocateVariablesRecursively() { - // The number of slots required for variables. - num_stack_slots_ = 0; - num_heap_slots_ = Context::MIN_CONTEXT_SLOTS; - - // Allocate variables for inner scopes. - for (int i = 0; i < inner_scopes_.length(); i++) { - inner_scopes_[i]->AllocateVariablesRecursively(); - } - - // Allocate variables for this scope. - // Parameters must be allocated first, if any. - if (is_function_scope()) AllocateParameterLocals(); - AllocateNonParameterLocals(); - - // Allocate context if necessary. - bool must_have_local_context = false; - if (scope_calls_eval_ || scope_contains_with_) { - // The context for the eval() call or 'with' statement in this scope. - // Unless we are in the global or an eval scope, we need a local - // context even if we didn't statically allocate any locals in it, - // and the compiler will access the context variable. If we are - // not in an inner scope, the scope is provided from the outside. - must_have_local_context = is_function_scope(); - } - - // If we didn't allocate any locals in the local context, then we only - // need the minimal number of slots if we must have a local context. - if (num_heap_slots_ == Context::MIN_CONTEXT_SLOTS && - !must_have_local_context) { - num_heap_slots_ = 0; - } - - // Allocation done. - ASSERT(num_heap_slots_ == 0 || num_heap_slots_ >= Context::MIN_CONTEXT_SLOTS); -} - -} } // namespace v8::internal |