Static resolution of outer variables in eval code.

src/parser.cc

 // Copyright 2011 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
@@ skipping 582 matching lines @@
       extension_(extension),
       pre_data_(pre_data),
       fni_(NULL),
       stack_overflow_(false),
       parenthesized_function_(false),
       harmony_scoping_(false) {
   AstNode::ResetIds();
 }
 
 
-FunctionLiteral* Parser::ParseProgram(Handle<String> source,
-                                      bool in_global_context,
-                                      StrictModeFlag strict_mode) {
+FunctionLiteral* Parser::ParseProgram(CompilationInfo* info) {
   ZoneScope zone_scope(isolate(), DONT_DELETE_ON_EXIT);
 
   HistogramTimerScope timer(isolate()->counters()->parse());
+  Handle<String> source(String::cast(script_->source()));
   isolate()->counters()->total_parse_size()->Increment(source->length());
   fni_ = new(zone()) FuncNameInferrer(isolate());
 
   // Initialize parser state.
   source->TryFlatten();
   if (source->IsExternalTwoByteString()) {
     // Notice that the stream is destroyed at the end of the branch block.
     // The last line of the blocks can't be moved outside, even though they're
     // identical calls.
     ExternalTwoByteStringUC16CharacterStream stream(
         Handle<ExternalTwoByteString>::cast(source), 0, source->length());
     scanner_.Initialize(&stream);
-    return DoParseProgram(source, in_global_context, strict_mode, &zone_scope);
+    return DoParseProgram(info, source, &zone_scope);
   } else {
     GenericStringUC16CharacterStream stream(source, 0, source->length());
     scanner_.Initialize(&stream);
-    return DoParseProgram(source, in_global_context, strict_mode, &zone_scope);
+    return DoParseProgram(info, source, &zone_scope);
   }
 }
 
 
-FunctionLiteral* Parser::DoParseProgram(Handle<String> source,
-                                        bool in_global_context,
-                                        StrictModeFlag strict_mode,
+FunctionLiteral* Parser::DoParseProgram(CompilationInfo* info,
+                                        Handle<String> source,
                                         ZoneScope* zone_scope) {
   ASSERT(top_scope_ == NULL);
   ASSERT(target_stack_ == NULL);
   if (pre_data_ != NULL) pre_data_->Initialize();
 
   // Compute the parsing mode.
   mode_ = FLAG_lazy ? PARSE_LAZILY : PARSE_EAGERLY;
   if (allow_natives_syntax_ || extension_ != NULL) mode_ = PARSE_EAGERLY;
 
-  ScopeType type = in_global_context ? GLOBAL_SCOPE : EVAL_SCOPE;
   Handle<String> no_name = isolate()->factory()->empty_symbol();
 
   FunctionLiteral* result = NULL;
-  { Scope* scope = NewScope(top_scope_, type);
+  { Scope* scope = NewScope(top_scope_, GLOBAL_SCOPE);;
+    info->SetGlobalScope(scope);
+    if (!info->is_global()) {
+      scope = Scope::DeserializeScopeChain(*info->calling_context(), scope);
+      scope = NewScope(scope, EVAL_SCOPE);
+    }
     scope->set_start_position(0);
     scope->set_end_position(source->length());
     FunctionState function_state(this, scope, isolate());
-    ASSERT(top_scope_->strict_mode_flag() == kNonStrictMode);
-    top_scope_->SetStrictModeFlag(strict_mode);
+    top_scope_->SetStrictModeFlag(info->strict_mode_flag());
     ZoneList<Statement*>* body = new(zone()) ZoneList<Statement*>(16);
     bool ok = true;
     int beg_loc = scanner().location().beg_pos;
     ParseSourceElements(body, Token::EOS, &ok);
     if (ok && top_scope_->is_strict_mode()) {
       CheckOctalLiteral(beg_loc, scanner().location().end_pos, &ok);
     }
 
     if (ok && harmony_scoping_) {
       CheckConflictingVarDeclarations(scope, &ok);
@@ skipping 65 matching lines @@
   fni_->PushEnclosingName(name);
 
   mode_ = PARSE_EAGERLY;
 
   // Place holder for the result.
   FunctionLiteral* result = NULL;
 
   {
     // Parse the function literal.
     Scope* scope = NewScope(top_scope_, GLOBAL_SCOPE);
+    info->SetGlobalScope(scope);
     if (!info->closure().is_null()) {
-      scope = Scope::DeserializeScopeChain(info, scope);
+      scope = Scope::DeserializeScopeChain(info->closure()->context(), scope);
     }
     FunctionState function_state(this, scope, isolate());
     ASSERT(scope->strict_mode_flag() == kNonStrictMode ||
            scope->strict_mode_flag() == info->strict_mode_flag());
     ASSERT(info->strict_mode_flag() == shared_info->strict_mode_flag());
     scope->SetStrictModeFlag(shared_info->strict_mode_flag());
     FunctionLiteral::Type type = shared_info->is_expression()
         ? (shared_info->is_anonymous()
               ? FunctionLiteral::ANONYMOUS_EXPRESSION
               : FunctionLiteral::NAMED_EXPRESSION)
@@ skipping 606 matching lines @@
                                bool resolve,
                                bool* ok) {
   Variable* var = NULL;
   // If we are inside a function, a declaration of a var/const variable is a
   // truly local variable, and the scope of the variable is always the function
   // scope.
   // Let/const variables in harmony mode are always added to the immediately
   // enclosing scope.
   Scope* declaration_scope = (mode == LET || mode == CONST_HARMONY)
       ? top_scope_ : top_scope_->DeclarationScope();
+  InitializationFlag init_flag = (fun != NULL || mode == VAR)
+      ? kCreatedInitialized : kNeedsInitialization;
 
   // If a function scope exists, then we can statically declare this
   // variable and also set its mode. In any case, a Declaration node
   // will be added to the scope so that the declaration can be added
   // to the corresponding activation frame at runtime if necessary.
   // For instance declarations inside an eval scope need to be added
   // to the calling function context.
   // Similarly, strict mode eval scope does not leak variable declarations to
   // the caller's scope so we declare all locals, too.
   // Also for block scoped let/const bindings the variable can be
   // statically declared.
   if (declaration_scope->is_function_scope() ||
       declaration_scope->is_strict_mode_eval_scope() ||
       declaration_scope->is_block_scope()) {
     // Declare the variable in the function scope.
     var = declaration_scope->LocalLookup(name);
     if (var == NULL) {
       // Declare the name.
-      InitializationFlag init_flag = (fun != NULL || mode == VAR)
-          ? kCreatedInitialized : kNeedsInitialization;
       var = declaration_scope->DeclareLocal(name, mode, init_flag);
     } else {
       // The name was declared in this scope before; check for conflicting
       // re-declarations. We have a conflict if either of the declarations is
       // not a var. There is similar code in runtime.cc in the Declare
       // functions. The function CheckNonConflictingScope checks for conflicting
       // var and let bindings from different scopes whereas this is a check for
       // conflicting declarations within the same scope. This check also covers
       //
       // function () { let x; { var x; } }
@@ skipping 42 matching lines @@
   // WARNING: This will lead to multiple declaration nodes for the
   // same variable if it is declared several times. This is not a
   // semantic issue as long as we keep the source order, but it may be
   // a performance issue since it may lead to repeated
   // Runtime::DeclareContextSlot() calls.
   VariableProxy* proxy = declaration_scope->NewUnresolved(
       name, scanner().location().beg_pos);
   declaration_scope->AddDeclaration(
       new(zone()) Declaration(proxy, mode, fun, top_scope_));
 
-  // For global const variables we bind the proxy to a variable.
   if ((mode == CONST || mode == CONST_HARMONY) &&
       declaration_scope->is_global_scope()) {
+    // For global const variables we bind the proxy to a variable.
     ASSERT(resolve);  // should be set by all callers
     Variable::Kind kind = Variable::NORMAL;
     var = new(zone()) Variable(declaration_scope,
                                name,
-                               CONST,
+                               mode,
                                true,
                                kind,
                                kNeedsInitialization);
+  } else if (declaration_scope->is_eval_scope() &&
+             !declaration_scope->is_strict_mode()) {
+    // For variable declarations in a non-strict eval scope the proxy is bound
+    // to a lookup variable to force a dynamic declaration using the
+    // DeclareContextSlot runtime function.
+    Variable::Kind kind = Variable::NORMAL;
+    var = new(zone()) Variable(declaration_scope,
+                               name,
+                               mode,
+                               true,
+                               kind,
+                               init_flag);
+    var->AllocateTo(Variable::LOOKUP, -1);
+    resolve = true;
   }
 
   // If requested and we have a local variable, bind the proxy to the variable
   // at parse-time. This is used for functions (and consts) declared inside
   // statements: the corresponding function (or const) variable must be in the
   // function scope and not a statement-local scope, e.g. as provided with a
   // 'with' statement:
   //
   //   with (obj) {
   //     function f() {}
@@ skipping 426 matching lines @@
         // the number of arguments (2 or 3).
         initialize =
             new(zone()) CallRuntime(
                 isolate(),
                 isolate()->factory()->InitializeVarGlobal_symbol(),
                 Runtime::FunctionForId(Runtime::kInitializeVarGlobal),
                 arguments);
       }
 
       block->AddStatement(new(zone()) ExpressionStatement(initialize));
+    } else if (needs_init) {
+      // Constant initializations always assign to the declared constant which
+      // is always at the function scope level. This is only relevant for
+      // dynamically looked-up variables and constants (the start context for
+      // constant lookups is always the function context, while it is the top
+      // context for var declared variables). Sigh...
+      // For 'let' and 'const' declared variables in harmony mode the
+      // initialization also always assigns to the declared variable.
+      ASSERT(proxy != NULL);
+      ASSERT(proxy->var() != NULL);
+      ASSERT(value != NULL);
+      Assignment* assignment =
+          new(zone()) Assignment(isolate(), init_op, proxy, value, position);
+      block->AddStatement(new(zone()) ExpressionStatement(assignment));
+      value = NULL;
     }
 
     // Add an assignment node to the initialization statement block if we still
-    // have a pending initialization value. We must distinguish between
-    // different kinds of declarations: 'var' initializations are simply
-    // assignments (with all the consequences if they are inside a 'with'
-    // statement - they may change a 'with' object property). Constant
-    // initializations always assign to the declared constant which is
-    // always at the function scope level. This is only relevant for
-    // dynamically looked-up variables and constants (the start context
-    // for constant lookups is always the function context, while it is
-    // the top context for var declared variables). Sigh...
-    // For 'let' and 'const' declared variables in harmony mode the
-    // initialization is in the same scope as the declaration. Thus dynamic
-    // lookups are unnecessary even if the block scope is inside a with.
+    // have a pending initialization value.
     if (value != NULL) {
+      ASSERT(mode == VAR);
+      // 'var' initializations are simply assignments (with all the consequences
+      // if they are inside a 'with' statement - they may change a 'with' object
+      // property).
       VariableProxy* proxy = initialization_scope->NewUnresolved(name);
       Assignment* assignment =
           new(zone()) Assignment(isolate(), init_op, proxy, value, position);
       block->AddStatement(new(zone()) ExpressionStatement(assignment));
     }
 
     if (fni_ != NULL) fni_->Leave();
   } while (peek() == Token::COMMA);
 
   // If there was a single non-const declaration, return it in the output
@@ skipping 3449 matching lines @@
   return !parser.failed();
 }
 
 
 bool ParserApi::Parse(CompilationInfo* info) {
   ASSERT(info->function() == NULL);
   FunctionLiteral* result = NULL;
   Handle<Script> script = info->script();
   bool harmony_scoping = !info->is_native() && FLAG_harmony_scoping;
   if (info->is_lazy()) {
+    ASSERT(!info->is_eval());
     bool allow_natives_syntax =
         FLAG_allow_natives_syntax ||
         info->is_native();
     Parser parser(script, allow_natives_syntax, NULL, NULL);
     parser.SetHarmonyScoping(harmony_scoping);
     result = parser.ParseLazy(info);
   } else {
     // Whether we allow %identifier(..) syntax.
     bool allow_natives_syntax =
         info->is_native() || FLAG_allow_natives_syntax;
     ScriptDataImpl* pre_data = info->pre_parse_data();
     Parser parser(script,
                   allow_natives_syntax,
                   info->extension(),
                   pre_data);
     parser.SetHarmonyScoping(harmony_scoping);
     if (pre_data != NULL && pre_data->has_error()) {
       Scanner::Location loc = pre_data->MessageLocation();
       const char* message = pre_data->BuildMessage();
       Vector<const char*> args = pre_data->BuildArgs();
       parser.ReportMessageAt(loc, message, args);
       DeleteArray(message);
       for (int i = 0; i < args.length(); i++) {
         DeleteArray(args[i]);
       }
       DeleteArray(args.start());
       ASSERT(info->isolate()->has_pending_exception());
     } else {
-      Handle<String> source = Handle<String>(String::cast(script->source()));
-      result = parser.ParseProgram(source,
-                                   info->is_global(),
-                                   info->strict_mode_flag());
+      result = parser.ParseProgram(info);
     }
   }
   info->SetFunction(result);
   return (result != NULL);
 }
 
 } }  // namespace v8::internal