scopes.cc.svn-base

Google浏览器V8内核代码

// 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.
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//       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
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#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
LocalsMap::LocalsMap(bool gotta_love_static_overloading) : HashMap()  {}

LocalsMap::LocalsMap() : HashMap(Match, &LocalsMapAllocator, 8)  {}
LocalsMap::~LocalsMap()  {}


Variable* LocalsMap::Declare(Scope* scope,
                             Handle<String> name,
                             Variable::Mode mode,
                             bool is_valid_LHS,
                             bool is_this) {
  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, is_this);
  }
  return reinterpret_cast<Variable*>(p->value);
}


Variable* LocalsMap::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()
  : inner_scopes_(0),
    locals_(false),
    temps_(0),
    params_(0),
    nonlocals_(0),
    unresolved_(0),
    decls_(0) {
}


Scope::Scope(Scope* outer_scope, Type type)
  : outer_scope_(outer_scope),
    inner_scopes_(4),
    type_(type),
    scope_name_(Factory::empty_symbol()),
    locals_(),
    temps_(4),
    params_(4),
    nonlocals_(4),
    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),
    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 =
      locals_.Declare(this, Factory::this_symbol(), Variable::VAR, false, true);
    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 may never be accessed, in which case it won't
    // be allocated during variable allocation.
    Declare(Factory::arguments_symbol(), Variable::VAR);
  }
}



Variable* Scope::Lookup(Handle<String> name) {
  return locals_.Lookup(name);
}


Variable* Scope::DeclareFunctionVar(Handle<String> name) {
  ASSERT(is_function_scope() && function_ == NULL);
  function_ = new Variable(this, name, Variable::CONST, true, false);
  return function_;
}


Variable* Scope::Declare(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 locals_.Declare(this, name, mode, true, false);
}


void Scope::AddParameter(Variable* var) {
  ASSERT(is_function_scope());
  ASSERT(Lookup(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, false);
  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(Visitor* 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 (LocalsMap::Entry* p = locals_.Start(); p != NULL; p = locals_.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);


void Scope::AllocateVariables() {
  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