[modules] Assign cell indices at validation time.

src/ast/modules.h

 // 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.
 
 #ifndef V8_AST_MODULES_H_
 #define V8_AST_MODULES_H_
 
 #include "src/parsing/scanner.h"  // Only for Scanner::Location.
 #include "src/pending-compilation-error-handler.h"
 #include "src/zone/zone-containers.h"
@@ skipping 59 matching lines @@
   // Check if module is well-formed and report error if not.
   // Also canonicalize indirect exports.
   bool Validate(ModuleScope* module_scope,
                 PendingCompilationErrorHandler* error_handler, Zone* zone);
 
   struct Entry : public ZoneObject {
     Scanner::Location location;
     const AstRawString* export_name;
     const AstRawString* local_name;
     const AstRawString* import_name;
+
     // The module_request value records the order in which modules are
     // requested. It also functions as an index into the ModuleInfo's array of
     // module specifiers and into the Module's array of requested modules.  A
     // negative value means no module request.
     int module_request;
 
+    // Import/export entries that are associated with a MODULE-allocated
+    // variable use the cell_index value to encode the location of their cell.
+    // Negative values are used for imports and positive values for exports.
+    // For entries that are not associated with a MODULE-allocated variable,
+    // cell_index is 0.
+    int cell_index;
+
     // TODO(neis): Remove local_name component?
     explicit Entry(Scanner::Location loc)
         : location(loc),
           export_name(nullptr),
           local_name(nullptr),
           import_name(nullptr),
-          module_request(-1) {}
+          module_request(-1),
+          cell_index(0) {}
 
     // (De-)serialization support.
     // Note that the location value is not preserved as it's only needed by the
     // parser.  (A Deserialize'd entry has an invalid location.)
     Handle<ModuleInfoEntry> Serialize(Isolate* isolate) const;
     static Entry* Deserialize(Isolate* isolate, AstValueFactory* avfactory,
                               Handle<ModuleInfoEntry> entry);
   };
 
   // Module requests.
   const ZoneMap<const AstRawString*, int>& module_requests() const {
     return module_requests_;
   }
 
   // Namespace imports.
   const ZoneList<const Entry*>& namespace_imports() const {
     return namespace_imports_;
   }
 
   // All the remaining imports, indexed by local name.
-  const ZoneMap<const AstRawString*, const Entry*>& regular_imports() const {
+  const ZoneMap<const AstRawString*, Entry*>& regular_imports() const {
     return regular_imports_;
   }
 
   // Star exports and explicitly indirect exports.
   const ZoneList<const Entry*>& special_exports() const {
     return special_exports_;
   }
 
   // All the remaining exports, indexed by local name.
   // After canonicalization (see Validate), these are exactly the local exports.
   const ZoneMultimap<const AstRawString*, Entry*>& regular_exports() const {
     return regular_exports_;
   }
 
   void AddRegularExport(Entry* entry) {
     DCHECK_NOT_NULL(entry->export_name);
     DCHECK_NOT_NULL(entry->local_name);
     DCHECK_NULL(entry->import_name);
     DCHECK_LT(entry->module_request, 0);
     regular_exports_.insert(std::make_pair(entry->local_name, entry));
   }
 
   void AddSpecialExport(const Entry* entry, Zone* zone) {
     DCHECK_NULL(entry->local_name);
     DCHECK_LE(0, entry->module_request);
     special_exports_.Add(entry, zone);
   }
 
-  void AddRegularImport(const Entry* entry) {
+  void AddRegularImport(Entry* entry) {
     DCHECK_NOT_NULL(entry->import_name);
     DCHECK_NOT_NULL(entry->local_name);
     DCHECK_NULL(entry->export_name);
     DCHECK_LE(0, entry->module_request);
     regular_imports_.insert(std::make_pair(entry->local_name, entry));
     // We don't care if there's already an entry for this local name, as in that
     // case we will report an error when declaring the variable.
   }
 
   void AddNamespaceImport(const Entry* entry, Zone* zone) {
     DCHECK_NULL(entry->import_name);
     DCHECK_NULL(entry->export_name);
     DCHECK_NOT_NULL(entry->local_name);
     DCHECK_LE(0, entry->module_request);
     namespace_imports_.Add(entry, zone);
   }
 
   Handle<FixedArray> SerializeRegularExports(Isolate* isolate,
                                              Zone* zone) const;
   void DeserializeRegularExports(Isolate* isolate, AstValueFactory* avfactory,
                                  Handle<FixedArray> data);
 
  private:
   // TODO(neis): Use STL datastructure instead of ZoneList?
   ZoneMap<const AstRawString*, int> module_requests_;
   ZoneList<const Entry*> special_exports_;
   ZoneList<const Entry*> namespace_imports_;
   ZoneMultimap<const AstRawString*, Entry*> regular_exports_;
-  ZoneMap<const AstRawString*, const Entry*> regular_imports_;
+  ZoneMap<const AstRawString*, Entry*> regular_imports_;
 
   // If there are multiple export entries with the same export name, return the
   // last of them (in source order).  Otherwise return nullptr.
   const Entry* FindDuplicateExport(Zone* zone) const;
 
   // Find any implicitly indirect exports and make them explicit.
   //
   // An explicitly indirect export is an export entry arising from an export
   // statement of the following form:
   //   export {a as c} from "X";
   // An implicitly indirect export corresponds to
   //   export {b as c};
   // in the presence of an import statement of the form
   //   import {a as b} from "X";
   // This function finds such implicitly indirect export entries and rewrites
   // them by filling in the import name and module request, as well as nulling
   // out the local name.  Effectively, it turns
   //   import {a as b} from "X"; export {b as c};
   // into:
   //   import {a as b} from "X"; export {a as c} from "X";
   // (The import entry is never deleted.)
   void MakeIndirectExportsExplicit(Zone* zone);
 
+  // Assign a cell_index of -1,-2,... to regular imports.
+  // Assign a cell_index of +1,+2,... to regular (local) exports.
+  // Assign a cell_index of 0 to anything else.
+  void AssignCellIndices();
+
   int AddModuleRequest(const AstRawString* specifier) {
     DCHECK_NOT_NULL(specifier);
     auto it = module_requests_
                   .insert(std::make_pair(specifier, module_requests_.size()))
                   .first;
     return it->second;
   }
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_AST_MODULES_H_