[modules] Fix bugs in assignments to exported variables.

src/interpreter/bytecode-generator.cc

 // Copyright 2015 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/interpreter/bytecode-generator.h"
 
 #include "src/ast/compile-time-value.h"
 #include "src/ast/scopes.h"
 #include "src/code-stubs.h"
 #include "src/compilation-info.h"
@@ skipping 2024 matching lines @@
       ModuleDescriptor* mod = scope()->GetModuleScope()->module();
       // There may be several export names for this local name, but it doesn't
       // matter which one we pick, as they all map to the same cell.
       auto it = mod->regular_exports().find(variable->raw_name());
       DCHECK(it != mod->regular_exports().end());
 
       RegisterList args = register_allocator()->NewRegisterList(2);
       builder()
           ->StoreAccumulatorInRegister(args[1])
           .LoadLiteral(it->second->export_name->string())
-          .StoreAccumulatorInRegister(args[0])
-          .CallRuntime(Runtime::kStoreModuleExport, args);
+          .StoreAccumulatorInRegister(args[0]);
+      if (needs_hole_check) {
+        builder()->CallRuntime(Runtime::kLoadModuleExport, args[0]);
+        BuildHoleCheckForVariableAssignment(variable, op);
+      }
+      builder()
+          ->CallRuntime(Runtime::kStoreModuleExport, args)
+          .LoadAccumulatorWithRegister(args[1]);
       break;
     }
   }
 }
 
 void BytecodeGenerator::VisitAssignment(Assignment* expr) {
   DCHECK(expr->target()->IsValidReferenceExpressionOrThis());
   Register object, key;
   RegisterList super_property_args;
   Handle<String> name;
@@ skipping 1126 matching lines @@
 }
 
 Runtime::FunctionId BytecodeGenerator::StoreKeyedToSuperRuntimeId() {
   return is_strict(language_mode()) ? Runtime::kStoreKeyedToSuper_Strict
                                     : Runtime::kStoreKeyedToSuper_Sloppy;
 }
 
 }  // namespace interpreter
 }  // namespace internal
 }  // namespace v8