Remove unused Module-related AST nodes and associated codegen

src/full-codegen.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #include "src/ast.h"
 #include "src/ast-numbering.h"
 #include "src/code-factory.h"
 #include "src/codegen.h"
@@ skipping 23 matching lines @@
 void BreakableStatementChecker::VisitVariableDeclaration(
     VariableDeclaration* decl) {
 }
 
 
 void BreakableStatementChecker::VisitFunctionDeclaration(
     FunctionDeclaration* decl) {
 }
 
 
-void BreakableStatementChecker::VisitModuleDeclaration(
-    ModuleDeclaration* decl) {
-}
-
-
 void BreakableStatementChecker::VisitImportDeclaration(
     ImportDeclaration* decl) {
 }
 
 
 void BreakableStatementChecker::VisitExportDeclaration(
     ExportDeclaration* decl) {
 }
 
 
-void BreakableStatementChecker::VisitModuleLiteral(ModuleLiteral* module) {
-}
-
-
-void BreakableStatementChecker::VisitModulePath(ModulePath* module) {
-}
-
-
-void BreakableStatementChecker::VisitModuleUrl(ModuleUrl* module) {
-}
-
-
-void BreakableStatementChecker::VisitModuleStatement(ModuleStatement* stmt) {
-}
-
-
 void BreakableStatementChecker::VisitBlock(Block* stmt) {
 }
 
 
 void BreakableStatementChecker::VisitExpressionStatement(
     ExpressionStatement* stmt) {
   // Check if expression is breakable.
   Visit(stmt->expression());
 }
 
@@ skipping 542 matching lines @@
 
 
 void FullCodeGenerator::DoTest(const TestContext* context) {
   DoTest(context->condition(),
          context->true_label(),
          context->false_label(),
          context->fall_through());
 }
 
 
-void FullCodeGenerator::AllocateModules(ZoneList<Declaration*>* declarations) {
-  DCHECK(scope_->is_script_scope());
-
-  for (int i = 0; i < declarations->length(); i++) {
-    ModuleDeclaration* declaration = declarations->at(i)->AsModuleDeclaration();
-    if (declaration != NULL) {
-      ModuleLiteral* module = declaration->module()->AsModuleLiteral();
-      if (module != NULL) {
-        Comment cmnt(masm_, "[ Link nested modules");
-        Scope* scope = module->body()->scope();
-        DCHECK(scope->module()->IsFrozen());
-
-        scope->module()->Allocate(scope->module_var()->index());
-
-        // Set up module context.
-        DCHECK(scope->module()->Index() >= 0);
-        __ Push(Smi::FromInt(scope->module()->Index()));
-        __ Push(scope->GetScopeInfo(isolate()));
-        __ CallRuntime(Runtime::kPushModuleContext, 2);
-        StoreToFrameField(StandardFrameConstants::kContextOffset,
-                          context_register());
-
-        AllocateModules(scope->declarations());
-
-        // Pop module context.
-        LoadContextField(context_register(), Context::PREVIOUS_INDEX);
-        // Update local stack frame context field.
-        StoreToFrameField(StandardFrameConstants::kContextOffset,
-                          context_register());
-      }
-    }
-  }
-}
-
-
-// Modules have their own local scope, represented by their own context.
-// Module instance objects have an accessor for every export that forwards
-// access to the respective slot from the module's context. (Exports that are
-// modules themselves, however, are simple data properties.)
-//
-// All modules have a _hosting_ scope/context, which (currently) is the
-// enclosing script scope. To deal with recursion, nested modules are hosted
-// by the same scope as global ones.
-//
-// For every (global or nested) module literal, the hosting context has an
-// internal slot that points directly to the respective module context. This
-// enables quick access to (statically resolved) module members by 2-dimensional
-// access through the hosting context. For example,
-//
-//   module A {
-//     let x;
-//     module B { let y; }
-//   }
-//   module C { let z; }
-//
-// allocates contexts as follows:
-//
-// [header| .A | .B | .C | A | C ]  (global)
-//           |    |    |
-//           |    |    +-- [header| z ]  (module)
-//           |    |
-//           |    +------- [header| y ]  (module)
-//           |
-//           +------------ [header| x | B ]  (module)
-//
-// Here, .A, .B, .C are the internal slots pointing to the hosted module
-// contexts, whereas A, B, C hold the actual instance objects (note that every
-// module context also points to the respective instance object through its
-// extension slot in the header).
-//
-// To deal with arbitrary recursion and aliases between modules,
-// they are created and initialized in several stages. Each stage applies to
-// all modules in the hosting script scope, including nested ones.
-//
-// 1. Allocate: for each module _literal_, allocate the module contexts and
-//    respective instance object and wire them up. This happens in the
-//    PushModuleContext runtime function, as generated by AllocateModules
-//    (invoked by VisitDeclarations in the hosting scope).
-//
-// 2. Bind: for each module _declaration_ (i.e. literals as well as aliases),
-//    assign the respective instance object to respective local variables. This
-//    happens in VisitModuleDeclaration, and uses the instance objects created
-//    in the previous stage.
-//    For each module _literal_, this phase also constructs a module descriptor
-//    for the next stage. This happens in VisitModuleLiteral.
-//
-// 3. Populate: invoke the DeclareModules runtime function to populate each
-//    _instance_ object with accessors for it exports. This is generated by
-//    DeclareModules (invoked by VisitDeclarations in the hosting scope again),
-//    and uses the descriptors generated in the previous stage.
-//
-// 4. Initialize: execute the module bodies (and other code) in sequence. This
-//    happens by the separate statements generated for module bodies. To reenter
-//    the module scopes properly, the parser inserted ModuleStatements.
-
 void FullCodeGenerator::VisitDeclarations(
     ZoneList<Declaration*>* declarations) {
-  Handle<FixedArray> saved_modules = modules_;
-  int saved_module_index = module_index_;
   ZoneList<Handle<Object> >* saved_globals = globals_;
   ZoneList<Handle<Object> > inner_globals(10, zone());
   globals_ = &inner_globals;
 
-  if (scope_->num_modules() != 0) {
-    // This is a scope hosting modules. Allocate a descriptor array to pass
-    // to the runtime for initialization.
-    Comment cmnt(masm_, "[ Allocate modules");
-    DCHECK(scope_->is_script_scope());
-    modules_ =
-        isolate()->factory()->NewFixedArray(scope_->num_modules(), TENURED);
-    module_index_ = 0;
-
-    // Generate code for allocating all modules, including nested ones.
-    // The allocated contexts are stored in internal variables in this scope.
-    AllocateModules(declarations);
-  }
-
   AstVisitor::VisitDeclarations(declarations);
 
-  if (scope_->num_modules() != 0) {
-    // TODO(ES6): This step, which creates module instance objects,
-    // can probably be delayed until an "import *" declaration
-    // reifies a module instance. Until imports are implemented,
-    // we skip it altogether.
-    //
-    // Initialize modules from descriptor array.
-    //  DCHECK(module_index_ == modules_->length());
-    //  DeclareModules(modules_);
-    modules_ = saved_modules;
-    module_index_ = saved_module_index;
-  }
-
   if (!globals_->is_empty()) {
     // Invoke the platform-dependent code generator to do the actual
     // declaration of the global functions and variables.
     Handle<FixedArray> array =
        isolate()->factory()->NewFixedArray(globals_->length(), TENURED);
     for (int i = 0; i < globals_->length(); ++i)
       array->set(i, *globals_->at(i));
     DeclareGlobals(array);
   }
 
   globals_ = saved_globals;
 }
 
 
-void FullCodeGenerator::VisitModuleLiteral(ModuleLiteral* module) {
-  Block* block = module->body();
-  Scope* saved_scope = scope();
-  scope_ = block->scope();
-  ModuleDescriptor* descriptor = scope_->module();
-
-  Comment cmnt(masm_, "[ ModuleLiteral");
-  SetStatementPosition(block);
-
-  DCHECK(!modules_.is_null());
-  DCHECK(module_index_ < modules_->length());
-  int index = module_index_++;
-
-  // Set up module context.
-  DCHECK(descriptor->Index() >= 0);
-  __ Push(Smi::FromInt(descriptor->Index()));
-  __ Push(Smi::FromInt(0));
-  __ CallRuntime(Runtime::kPushModuleContext, 2);
-  StoreToFrameField(StandardFrameConstants::kContextOffset, context_register());
-
-  {
-    Comment cmnt(masm_, "[ Declarations");
-    VisitDeclarations(scope_->declarations());
-  }
-
-  // Populate the module description.
-  Handle<ModuleInfo> description =
-      ModuleInfo::Create(isolate(), descriptor, scope_);
-  modules_->set(index, *description);
-
-  scope_ = saved_scope;
-  // Pop module context.
-  LoadContextField(context_register(), Context::PREVIOUS_INDEX);
-  // Update local stack frame context field.
-  StoreToFrameField(StandardFrameConstants::kContextOffset, context_register());
-}
-
-
-// TODO(adamk): Delete ModulePath.
-void FullCodeGenerator::VisitModulePath(ModulePath* module) {
-}
-
-
-// TODO(adamk): Delete ModuleUrl.
-void FullCodeGenerator::VisitModuleUrl(ModuleUrl* module) {
-}
-
-
 int FullCodeGenerator::DeclareGlobalsFlags() {
   DCHECK(DeclareGlobalsLanguageMode::is_valid(language_mode()));
   return DeclareGlobalsEvalFlag::encode(is_eval()) |
          DeclareGlobalsNativeFlag::encode(is_native()) |
          DeclareGlobalsLanguageMode::encode(language_mode());
 }
 
 
 void FullCodeGenerator::SetFunctionPosition(FunctionLiteral* fun) {
   CodeGenerator::RecordPositions(masm_, fun->start_position());
@@ skipping 213 matching lines @@
 
   {
     EnterBlockScopeIfNeeded block_scope_state(
         this, stmt->scope(), stmt->EntryId(), stmt->DeclsId(), stmt->ExitId());
     VisitStatements(stmt->statements());
     __ bind(nested_block.break_label());
   }
 }
 
 
-void FullCodeGenerator::VisitModuleStatement(ModuleStatement* stmt) {
-  Comment cmnt(masm_, "[ Module context");
-
-  DCHECK(stmt->body()->scope()->is_module_scope());
-
-  __ Push(Smi::FromInt(stmt->body()->scope()->module()->Index()));
-  __ Push(Smi::FromInt(0));
-  __ CallRuntime(Runtime::kPushModuleContext, 2);
-  StoreToFrameField(
-      StandardFrameConstants::kContextOffset, context_register());
-
-  Scope* saved_scope = scope_;
-  scope_ = stmt->body()->scope();
-  VisitStatements(stmt->body()->statements());
-  scope_ = saved_scope;
-  LoadContextField(context_register(), Context::PREVIOUS_INDEX);
-  // Update local stack frame context field.
-  StoreToFrameField(StandardFrameConstants::kContextOffset,
-                    context_register());
-}
-
-
 void FullCodeGenerator::VisitExpressionStatement(ExpressionStatement* stmt) {
   Comment cmnt(masm_, "[ ExpressionStatement");
   SetStatementPosition(stmt);
   VisitForEffect(stmt->expression());
 }
 
 
 void FullCodeGenerator::VisitEmptyStatement(EmptyStatement* stmt) {
   Comment cmnt(masm_, "[ EmptyStatement");
   SetStatementPosition(stmt);
@@ skipping 761 matching lines @@
   }
   codegen_->PrepareForBailoutForId(exit_id_, NO_REGISTERS);
   codegen_->scope_ = saved_scope_;
 }
 
 
 #undef __
 
 
 } }  // namespace v8::internal