0c7af39737
surrounding context to figure out if the variable could be global. If the variable could be global we check context extension objects at runtime and use a global LoadIC if no variables have been introduced by eval. Fix crash bug when loading function arguments from inside eval. The shadowed variable in the DYNAMIC_LOCAL case does not rewrite to a slot in that case. Review URL: http://codereview.chromium.org/28027 git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@1348 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
946 lines
32 KiB
C++
946 lines
32 KiB
C++
// Copyright 2006-2008 the V8 project authors. All rights reserved.
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are
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// met:
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//
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// * Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above
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// copyright notice, this list of conditions and the following
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// disclaimer in the documentation and/or other materials provided
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// with the distribution.
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// * Neither the name of Google Inc. nor the names of its
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// contributors may be used to endorse or promote products derived
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// from this software without specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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#include "v8.h"
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#include "prettyprinter.h"
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#include "scopeinfo.h"
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#include "scopes.h"
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namespace v8 { namespace internal {
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// ----------------------------------------------------------------------------
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// A Zone allocator for use with LocalsMap.
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class ZoneAllocator: public Allocator {
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public:
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/* nothing to do */
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virtual ~ZoneAllocator() {}
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virtual void* New(size_t size) { return Zone::New(size); }
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/* ignored - Zone is freed in one fell swoop */
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virtual void Delete(void* p) {}
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};
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static ZoneAllocator LocalsMapAllocator;
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// ----------------------------------------------------------------------------
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// Implementation of LocalsMap
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//
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// Note: We are storing the handle locations as key values in the hash map.
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// When inserting a new variable via Declare(), we rely on the fact that
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// the handle location remains alive for the duration of that variable
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// use. Because a Variable holding a handle with the same location exists
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// this is ensured.
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static bool Match(void* key1, void* key2) {
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String* name1 = *reinterpret_cast<String**>(key1);
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String* name2 = *reinterpret_cast<String**>(key2);
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ASSERT(name1->IsSymbol());
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ASSERT(name2->IsSymbol());
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return name1 == name2;
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}
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// Dummy constructor
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LocalsMap::LocalsMap(bool gotta_love_static_overloading) : HashMap() {}
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LocalsMap::LocalsMap() : HashMap(Match, &LocalsMapAllocator, 8) {}
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LocalsMap::~LocalsMap() {}
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Variable* LocalsMap::Declare(Scope* scope,
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Handle<String> name,
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Variable::Mode mode,
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bool is_valid_LHS,
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bool is_this) {
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HashMap::Entry* p = HashMap::Lookup(name.location(), name->Hash(), true);
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if (p->value == NULL) {
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// The variable has not been declared yet -> insert it.
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ASSERT(p->key == name.location());
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p->value = new Variable(scope, name, mode, is_valid_LHS, is_this);
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}
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return reinterpret_cast<Variable*>(p->value);
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}
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Variable* LocalsMap::Lookup(Handle<String> name) {
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HashMap::Entry* p = HashMap::Lookup(name.location(), name->Hash(), false);
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if (p != NULL) {
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ASSERT(*reinterpret_cast<String**>(p->key) == *name);
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ASSERT(p->value != NULL);
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return reinterpret_cast<Variable*>(p->value);
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}
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return NULL;
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}
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// ----------------------------------------------------------------------------
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// Implementation of Scope
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// Dummy constructor
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Scope::Scope()
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: inner_scopes_(0),
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locals_(false),
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temps_(0),
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params_(0),
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nonlocals_(0),
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unresolved_(0),
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decls_(0) {
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}
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Scope::Scope(Scope* outer_scope, Type type)
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: outer_scope_(outer_scope),
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inner_scopes_(4),
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type_(type),
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scope_name_(Factory::empty_symbol()),
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locals_(),
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temps_(4),
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params_(4),
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nonlocals_(4),
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unresolved_(16),
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decls_(4),
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receiver_(NULL),
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function_(NULL),
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arguments_(NULL),
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arguments_shadow_(NULL),
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illegal_redecl_(NULL),
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scope_inside_with_(false),
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scope_contains_with_(false),
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scope_calls_eval_(false),
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outer_scope_calls_eval_(false),
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inner_scope_calls_eval_(false),
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outer_scope_is_eval_scope_(false),
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force_eager_compilation_(false),
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num_stack_slots_(0),
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num_heap_slots_(0) {
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// At some point we might want to provide outer scopes to
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// eval scopes (by walking the stack and reading the scope info).
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// In that case, the ASSERT below needs to be adjusted.
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ASSERT((type == GLOBAL_SCOPE || type == EVAL_SCOPE) == (outer_scope == NULL));
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ASSERT(!HasIllegalRedeclaration());
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}
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void Scope::Initialize(bool inside_with) {
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// Add this scope as a new inner scope of the outer scope.
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if (outer_scope_ != NULL) {
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outer_scope_->inner_scopes_.Add(this);
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scope_inside_with_ = outer_scope_->scope_inside_with_ || inside_with;
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} else {
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scope_inside_with_ = inside_with;
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}
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// Declare convenience variables.
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// Declare and allocate receiver (even for the global scope, and even
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// if naccesses_ == 0).
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// NOTE: When loading parameters in the global scope, we must take
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// care not to access them as properties of the global object, but
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// instead load them directly from the stack. Currently, the only
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// such parameter is 'this' which is passed on the stack when
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// invoking scripts
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{ Variable* var =
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locals_.Declare(this, Factory::this_symbol(), Variable::VAR, false, true);
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var->rewrite_ = new Slot(var, Slot::PARAMETER, -1);
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receiver_ = new VariableProxy(Factory::this_symbol(), true, false);
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receiver_->BindTo(var);
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}
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if (is_function_scope()) {
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// Declare 'arguments' variable which exists in all functions.
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// Note that it may never be accessed, in which case it won't
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// be allocated during variable allocation.
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Declare(Factory::arguments_symbol(), Variable::VAR);
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}
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}
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Variable* Scope::LookupLocal(Handle<String> name) {
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return locals_.Lookup(name);
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}
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Variable* Scope::Lookup(Handle<String> name) {
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for (Scope* scope = this;
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scope != NULL;
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scope = scope->outer_scope()) {
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Variable* var = scope->LookupLocal(name);
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if (var != NULL) return var;
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}
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return NULL;
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}
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Variable* Scope::DeclareFunctionVar(Handle<String> name) {
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ASSERT(is_function_scope() && function_ == NULL);
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function_ = new Variable(this, name, Variable::CONST, true, false);
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return function_;
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}
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Variable* Scope::Declare(Handle<String> name, Variable::Mode mode) {
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// DYNAMIC variables are introduces during variable allocation,
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// INTERNAL variables are allocated explicitly, and TEMPORARY
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// variables are allocated via NewTemporary().
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ASSERT(mode == Variable::VAR || mode == Variable::CONST);
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return locals_.Declare(this, name, mode, true, false);
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}
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void Scope::AddParameter(Variable* var) {
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ASSERT(is_function_scope());
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ASSERT(LookupLocal(var->name()) == var);
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params_.Add(var);
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}
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VariableProxy* Scope::NewUnresolved(Handle<String> name, bool inside_with) {
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// Note that we must not share the unresolved variables with
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// the same name because they may be removed selectively via
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// RemoveUnresolved().
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VariableProxy* proxy = new VariableProxy(name, false, inside_with);
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unresolved_.Add(proxy);
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return proxy;
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}
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void Scope::RemoveUnresolved(VariableProxy* var) {
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// Most likely (always?) any variable we want to remove
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// was just added before, so we search backwards.
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for (int i = unresolved_.length(); i-- > 0;) {
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if (unresolved_[i] == var) {
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unresolved_.Remove(i);
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return;
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}
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}
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}
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VariableProxy* Scope::NewTemporary(Handle<String> name) {
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Variable* var = new Variable(this, name, Variable::TEMPORARY, true, false);
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VariableProxy* tmp = new VariableProxy(name, false, false);
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tmp->BindTo(var);
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temps_.Add(var);
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return tmp;
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}
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void Scope::AddDeclaration(Declaration* declaration) {
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decls_.Add(declaration);
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}
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void Scope::SetIllegalRedeclaration(Expression* expression) {
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// Only set the illegal redeclaration expression the
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// first time the function is called.
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if (!HasIllegalRedeclaration()) {
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illegal_redecl_ = expression;
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}
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ASSERT(HasIllegalRedeclaration());
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}
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void Scope::VisitIllegalRedeclaration(AstVisitor* visitor) {
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ASSERT(HasIllegalRedeclaration());
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illegal_redecl_->Accept(visitor);
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}
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template<class Allocator>
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void Scope::CollectUsedVariables(List<Variable*, Allocator>* locals) {
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// Collect variables in this scope.
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// Note that the function_ variable - if present - is not
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// collected here but handled separately in ScopeInfo
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// which is the current user of this function).
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for (int i = 0; i < temps_.length(); i++) {
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Variable* var = temps_[i];
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if (var->var_uses()->is_used()) {
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locals->Add(var);
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}
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}
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for (LocalsMap::Entry* p = locals_.Start(); p != NULL; p = locals_.Next(p)) {
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Variable* var = reinterpret_cast<Variable*>(p->value);
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if (var->var_uses()->is_used()) {
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locals->Add(var);
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}
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}
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}
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// Make sure the method gets instantiated by the template system.
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template void Scope::CollectUsedVariables(
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List<Variable*, FreeStoreAllocationPolicy>* locals);
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template void Scope::CollectUsedVariables(
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List<Variable*, PreallocatedStorage>* locals);
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void Scope::AllocateVariables(Handle<Context> context) {
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ASSERT(outer_scope_ == NULL); // eval or global scopes only
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// 1) Propagate scope information.
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// If we are in an eval scope, we may have other outer scopes about
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// which we don't know anything at this point. Thus we must be conservative
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// and assume they may invoke eval themselves. Eventually we could capture
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// this information in the ScopeInfo and then use it here (by traversing
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// the call chain stack, at compile time).
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bool eval_scope = is_eval_scope();
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PropagateScopeInfo(eval_scope, eval_scope);
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// 2) Resolve variables.
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Scope* global_scope = NULL;
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if (is_global_scope()) global_scope = this;
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ResolveVariablesRecursively(global_scope, context);
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// 3) Allocate variables.
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AllocateVariablesRecursively();
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}
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bool Scope::AllowsLazyCompilation() const {
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return !force_eager_compilation_ && HasTrivialOuterContext();
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}
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bool Scope::HasTrivialContext() const {
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// A function scope has a trivial context if it always is the global
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// context. We iteratively scan out the context chain to see if
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// there is anything that makes this scope non-trivial; otherwise we
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// return true.
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for (const Scope* scope = this; scope != NULL; scope = scope->outer_scope_) {
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if (scope->is_eval_scope()) return false;
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if (scope->scope_inside_with_) return false;
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if (scope->num_heap_slots_ > 0) return false;
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}
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return true;
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}
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bool Scope::HasTrivialOuterContext() const {
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Scope* outer = outer_scope_;
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if (outer == NULL) return true;
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// Note that the outer context may be trivial in general, but the current
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// scope may be inside a 'with' statement in which case the outer context
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// for this scope is not trivial.
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return !scope_inside_with_ && outer->HasTrivialContext();
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}
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int Scope::ContextChainLength(Scope* scope) {
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int n = 0;
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for (Scope* s = this; s != scope; s = s->outer_scope_) {
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ASSERT(s != NULL); // scope must be in the scope chain
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if (s->num_heap_slots() > 0) n++;
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}
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return n;
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}
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#ifdef DEBUG
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static const char* Header(Scope::Type type) {
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switch (type) {
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case Scope::EVAL_SCOPE: return "eval";
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case Scope::FUNCTION_SCOPE: return "function";
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case Scope::GLOBAL_SCOPE: return "global";
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}
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UNREACHABLE();
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return NULL;
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}
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static void Indent(int n, const char* str) {
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PrintF("%*s%s", n, "", str);
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}
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static void PrintName(Handle<String> name) {
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SmartPointer<char> s = name->ToCString(DISALLOW_NULLS);
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PrintF("%s", *s);
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}
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static void PrintVar(PrettyPrinter* printer, int indent, Variable* var) {
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if (var->var_uses()->is_used() || var->rewrite() != NULL) {
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Indent(indent, Variable::Mode2String(var->mode()));
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PrintF(" ");
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PrintName(var->name());
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PrintF("; // ");
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if (var->rewrite() != NULL) PrintF("%s, ", printer->Print(var->rewrite()));
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if (var->is_accessed_from_inner_scope()) PrintF("inner scope access, ");
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PrintF("var ");
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var->var_uses()->Print();
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PrintF(", obj ");
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var->obj_uses()->Print();
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PrintF("\n");
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}
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}
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void Scope::Print(int n) {
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int n0 = (n > 0 ? n : 0);
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int n1 = n0 + 2; // indentation
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// Print header.
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Indent(n0, Header(type_));
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if (scope_name_->length() > 0) {
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PrintF(" ");
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PrintName(scope_name_);
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}
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// Print parameters, if any.
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if (is_function_scope()) {
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PrintF(" (");
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for (int i = 0; i < params_.length(); i++) {
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if (i > 0) PrintF(", ");
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PrintName(params_[i]->name());
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}
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PrintF(")");
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}
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PrintF(" {\n");
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// Function name, if any (named function literals, only).
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if (function_ != NULL) {
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Indent(n1, "// (local) function name: ");
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PrintName(function_->name());
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PrintF("\n");
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}
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// Scope info.
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if (HasTrivialOuterContext()) {
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Indent(n1, "// scope has trivial outer context\n");
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}
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if (scope_inside_with_) Indent(n1, "// scope inside 'with'\n");
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if (scope_contains_with_) Indent(n1, "// scope contains 'with'\n");
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if (scope_calls_eval_) Indent(n1, "// scope calls 'eval'\n");
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if (outer_scope_calls_eval_) Indent(n1, "// outer scope calls 'eval'\n");
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if (inner_scope_calls_eval_) Indent(n1, "// inner scope calls 'eval'\n");
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if (outer_scope_is_eval_scope_) {
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Indent(n1, "// outer scope is 'eval' scope\n");
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}
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if (num_stack_slots_ > 0) { Indent(n1, "// ");
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PrintF("%d stack slots\n", num_stack_slots_); }
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if (num_heap_slots_ > 0) { Indent(n1, "// ");
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PrintF("%d heap slots\n", num_heap_slots_); }
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// Print locals.
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PrettyPrinter printer;
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Indent(n1, "// function var\n");
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if (function_ != NULL) {
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PrintVar(&printer, n1, function_);
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}
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Indent(n1, "// temporary vars\n");
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for (int i = 0; i < temps_.length(); i++) {
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PrintVar(&printer, n1, temps_[i]);
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}
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Indent(n1, "// local vars\n");
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for (LocalsMap::Entry* p = locals_.Start(); p != NULL; p = locals_.Next(p)) {
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Variable* var = reinterpret_cast<Variable*>(p->value);
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PrintVar(&printer, n1, var);
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}
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Indent(n1, "// nonlocal vars\n");
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for (int i = 0; i < nonlocals_.length(); i++)
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PrintVar(&printer, n1, nonlocals_[i]);
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// Print inner scopes (disable by providing negative n).
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if (n >= 0) {
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for (int i = 0; i < inner_scopes_.length(); i++) {
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PrintF("\n");
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inner_scopes_[i]->Print(n1);
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}
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}
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Indent(n0, "}\n");
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}
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#endif // DEBUG
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Variable* Scope::NonLocal(Handle<String> name, Variable::Mode mode) {
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// Space optimization: reuse existing non-local with the same name
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// and mode.
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for (int i = 0; i < nonlocals_.length(); i++) {
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Variable* var = nonlocals_[i];
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if (var->name().is_identical_to(name) && var->mode() == mode) {
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return var;
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}
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}
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// Otherwise create a new non-local and add it to the list.
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Variable* var = new Variable(NULL, name, mode, true, false);
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nonlocals_.Add(var);
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// Allocate it by giving it a dynamic lookup.
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var->rewrite_ = new Slot(var, Slot::LOOKUP, -1);
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return var;
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}
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// Lookup a variable starting with this scope. The result is either
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// the statically resolved (local!) variable belonging to an outer scope,
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// 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 = LookupLocal(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 = new Variable(global_scope, proxy->name(),
|
|
Variable::DYNAMIC, true, false);
|
|
// Ideally we simply rewrite these variables into property
|
|
// accesses. Unfortunately, we cannot do this here at the
|
|
// moment because then we can't differentiate between
|
|
// global variable ('x') and global property ('this.x') access.
|
|
// If 'x' doesn't exist, the former leads to an error, while the
|
|
// latter returns undefined. Sigh...
|
|
// var->rewrite_ = new Property(new Literal(env_->global()),
|
|
// new Literal(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, or if it is a global variable.
|
|
// 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->is_global())) {
|
|
var->var_uses()->RecordAccess(1);
|
|
}
|
|
return 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.
|
|
// Exceptions: Global variables and temporary variables must
|
|
// never be allocated in the (FixedArray part of 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 = LookupLocal(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, false);
|
|
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);
|
|
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 (MustAllocate(var) && var->rewrite_ == NULL) {
|
|
if (MustAllocateInContext(var)) {
|
|
AllocateHeapSlot(var);
|
|
} else {
|
|
AllocateStackSlot(var);
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
void Scope::AllocateNonParameterLocals() {
|
|
// Each variable occurs exactly once in the locals_ list; all
|
|
// variables that have no rewrite yet are non-parameter locals.
|
|
|
|
// Sort them according to use such that the locals with more uses
|
|
// get allocated first.
|
|
if (FLAG_usage_computation) {
|
|
// This is currently not implemented.
|
|
}
|
|
|
|
for (int i = 0; i < temps_.length(); i++) {
|
|
AllocateNonParameterLocal(temps_[i]);
|
|
}
|
|
|
|
for (LocalsMap::Entry* p = locals_.Start(); p != NULL; p = locals_.Next(p)) {
|
|
Variable* var = reinterpret_cast<Variable*>(p->value);
|
|
AllocateNonParameterLocal(var);
|
|
}
|
|
|
|
// Note: 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
|