Implement TDZ in StoreIC for top-level lexicals.

src/hydrogen.cc

 // Copyright 2013 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/hydrogen.h"
 
 #include <sstream>
 
 #include "src/v8.h"
 
@@ skipping 5309 matching lines @@
 
       if (FLAG_harmony_scoping) {
         Handle<ScriptContextTable> script_contexts(
             global->native_context()->script_context_table());
         ScriptContextTable::LookupResult lookup;
         if (ScriptContextTable::Lookup(script_contexts, variable->name(),
                                        &lookup)) {
           Handle<Context> script_context = ScriptContextTable::GetContext(
               script_contexts, lookup.context_index);
           Handle<Object> current_value =
-              FixedArray::get(script_context, lookup.context_index);
+              FixedArray::get(script_context, lookup.slot_index);
 
           // If the values is not the hole, it will stay initialized,
           // so no need to generate a check.
           if (*current_value == *isolate()->factory()->the_hole_value()) {
             return Bailout(kReferenceToUninitializedVariable);
           }
           HInstruction* result = New<HLoadNamedField>(
               Add<HConstant>(script_context), nullptr,
               HObjectAccess::ForContextSlot(lookup.slot_index));
           return ast_context()->ReturnInstruction(result, expr->id());
@@ skipping 1140 matching lines @@
   if (FLAG_harmony_scoping) {
     Handle<ScriptContextTable> script_contexts(
         global->native_context()->script_context_table());
     ScriptContextTable::LookupResult lookup;
     if (ScriptContextTable::Lookup(script_contexts, var->name(), &lookup)) {
       if (lookup.mode == CONST) {
         return Bailout(kNonInitializerAssignmentToConst);
       }
       Handle<Context> script_context =
           ScriptContextTable::GetContext(script_contexts, lookup.context_index);
+
+      Handle<Object> current_value =
+          FixedArray::get(script_context, lookup.slot_index);
+
+      // If the values is not the hole, it will stay initialized,
+      // so no need to generate a check.
+      if (*current_value == *isolate()->factory()->the_hole_value()) {
+        return Bailout(kReferenceToUninitializedVariable);
+      }
+
       HStoreNamedField* instr = Add<HStoreNamedField>(
           Add<HConstant>(script_context),
           HObjectAccess::ForContextSlot(lookup.slot_index), value);
       USE(instr);
       DCHECK(instr->HasObservableSideEffects());
       Add<HSimulate>(ast_id, REMOVABLE_SIMULATE);
       return;
     }
   }
 
@@ skipping 6877 matching lines @@
   if (ShouldProduceTraceOutput()) {
     isolate()->GetHTracer()->TraceHydrogen(name(), graph_);
   }
 
 #ifdef DEBUG
   graph_->Verify(false);  // No full verify.
 #endif
 }
 
 } }  // namespace v8::internal