Do not look for the slot in the ScopeInfo's global range when it's not necessary.

src/scopeinfo.cc

Index: src/scopeinfo.cc
diff --git a/src/scopeinfo.cc b/src/scopeinfo.cc
index 5492922c455843acc2b3b2097bbe76526a2b6c01..75938c355987087b69179a3875014fc62fcc7797 100644
--- a/src/scopeinfo.cc
+++ b/src/scopeinfo.cc
@@ -524,57 +524,73 @@ int ScopeInfo::StackSlotIndex(String* name) {
 
 int ScopeInfo::ContextSlotIndex(Handle<ScopeInfo> scope_info,
                                 Handle<String> name, VariableMode* mode,
-                                VariableLocation* location,
                                 InitializationFlag* init_flag,
                                 MaybeAssignedFlag* maybe_assigned_flag) {
   DCHECK(name->IsInternalizedString());
   DCHECK(mode != NULL);
-  DCHECK(location != NULL);
   DCHECK(init_flag != NULL);
   if (scope_info->length() > 0) {
     ContextSlotCache* context_slot_cache =
         scope_info->GetIsolate()->context_slot_cache();
-    int result = context_slot_cache->Lookup(*scope_info, *name, mode, location,
-                                            init_flag, maybe_assigned_flag);
+    int result = context_slot_cache->Lookup(*scope_info, *name, mode, init_flag,
+                                            maybe_assigned_flag);
     if (result != ContextSlotCache::kNotFound) {
       DCHECK(result < scope_info->ContextLength());
       return result;
     }
 
+    int start = scope_info->ContextLocalNameEntriesIndex();
+    int end = scope_info->ContextLocalNameEntriesIndex() +
+              scope_info->ContextLocalCount();
+    for (int i = start; i < end; ++i) {
+      if (*name == scope_info->get(i)) {
+        int var = i - start;
+        *mode = scope_info->ContextLocalMode(var);
+        *init_flag = scope_info->ContextLocalInitFlag(var);
+        *maybe_assigned_flag = scope_info->ContextLocalMaybeAssignedFlag(var);
+        result = Context::MIN_CONTEXT_SLOTS + var;
+
+        context_slot_cache->Update(scope_info, name, *mode, *init_flag,
+                                   *maybe_assigned_flag, result);
+        DCHECK(result < scope_info->ContextLength());
+        return result;
+      }
+    }
+    // Cache as not found. Mode, init flag and maybe assigned flag don't matter.
+    context_slot_cache->Update(scope_info, name, TEMPORARY,
+                               kNeedsInitialization, kNotAssigned, -1);
+  }
+  return -1;
+}
+
+
+int ScopeInfo::ContextGlobalSlotIndex(Handle<ScopeInfo> scope_info,
+                                      Handle<String> name, VariableMode* mode,
+                                      InitializationFlag* init_flag,
+                                      MaybeAssignedFlag* maybe_assigned_flag) {
+  DCHECK(name->IsInternalizedString());
+  DCHECK(mode != NULL);
+  DCHECK(init_flag != NULL);
+  if (scope_info->length() > 0) {
+    // This is to ensure that ContextLocalMode() and co. queries would work.
     DCHECK_EQ(scope_info->ContextGlobalNameEntriesIndex(),
               scope_info->ContextLocalNameEntriesIndex() +
                   scope_info->ContextLocalCount());
-    int start = scope_info->ContextLocalNameEntriesIndex();
+    int base = scope_info->ContextLocalNameEntriesIndex();
+    int start = scope_info->ContextGlobalNameEntriesIndex();
     int end = scope_info->ContextGlobalNameEntriesIndex() +
               scope_info->ContextGlobalCount();
     for (int i = start; i < end; ++i) {
       if (*name == scope_info->get(i)) {
-        int var = i - start;
+        int var = i - base;
         *mode = scope_info->ContextLocalMode(var);
         *init_flag = scope_info->ContextLocalInitFlag(var);
         *maybe_assigned_flag = scope_info->ContextLocalMaybeAssignedFlag(var);
-
-        if (var < scope_info->ContextLocalCount()) {
-          *location = VariableLocation::CONTEXT;
-          result = Context::MIN_CONTEXT_SLOTS + var;
-        } else {
-          var -= scope_info->ContextLocalCount();
-          *location = VariableLocation::GLOBAL;
-          result = Context::MIN_CONTEXT_SLOTS +
-                   scope_info->ContextLocalCount() + var;
-        }
-
-        context_slot_cache->Update(scope_info, name, *mode, *location,
-                                   *init_flag, *maybe_assigned_flag, result);
+        int result = Context::MIN_CONTEXT_SLOTS + var;
         DCHECK(result < scope_info->ContextLength());
         return result;
       }
     }
-    // Cache as not found. Mode, location, init flag and maybe assigned flag
-    // don't matter.
-    context_slot_cache->Update(scope_info, name, TEMPORARY,
-                               VariableLocation::CONTEXT, kNeedsInitialization,
-                               kNotAssigned, -1);
   }
   return -1;
 }
@@ -701,7 +717,6 @@ int ContextSlotCache::Hash(Object* data, String* name) {
 
 
 int ContextSlotCache::Lookup(Object* data, String* name, VariableMode* mode,
-                             VariableLocation* location,
                              InitializationFlag* init_flag,
                              MaybeAssignedFlag* maybe_assigned_flag) {
   int index = Hash(data, name);
@@ -709,7 +724,6 @@ int ContextSlotCache::Lookup(Object* data, String* name, VariableMode* mode,
   if ((key.data == data) && key.name->Equals(name)) {
     Value result(values_[index]);
     if (mode != NULL) *mode = result.mode();
-    if (location != NULL) *location = result.location();
     if (init_flag != NULL) *init_flag = result.initialization_flag();
     if (maybe_assigned_flag != NULL)
       *maybe_assigned_flag = result.maybe_assigned_flag();
@@ -720,8 +734,7 @@ int ContextSlotCache::Lookup(Object* data, String* name, VariableMode* mode,
 
 
 void ContextSlotCache::Update(Handle<Object> data, Handle<String> name,
-                              VariableMode mode, VariableLocation location,
-                              InitializationFlag init_flag,
+                              VariableMode mode, InitializationFlag init_flag,
                               MaybeAssignedFlag maybe_assigned_flag,
                               int slot_index) {
   DisallowHeapAllocation no_gc;
@@ -734,11 +747,10 @@ void ContextSlotCache::Update(Handle<Object> data, Handle<String> name,
     key.data = *data;
     key.name = *internalized_name;
     // Please note value only takes a uint as index.
-    values_[index] = Value(mode, location, init_flag, maybe_assigned_flag,
+    values_[index] = Value(mode, init_flag, maybe_assigned_flag,
                            slot_index - kNotFound).raw();
 #ifdef DEBUG
-    ValidateEntry(data, name, mode, location, init_flag, maybe_assigned_flag,
-                  slot_index);
+    ValidateEntry(data, name, mode, init_flag, maybe_assigned_flag, slot_index);
 #endif
   }
 }
@@ -753,7 +765,6 @@ void ContextSlotCache::Clear() {
 
 void ContextSlotCache::ValidateEntry(Handle<Object> data, Handle<String> name,
                                      VariableMode mode,
-                                     VariableLocation location,
                                      InitializationFlag init_flag,
                                      MaybeAssignedFlag maybe_assigned_flag,
                                      int slot_index) {
@@ -767,7 +778,6 @@ void ContextSlotCache::ValidateEntry(Handle<Object> data, Handle<String> name,
     DCHECK(key.name->Equals(*name));
     Value result(values_[index]);
     DCHECK(result.mode() == mode);
-    DCHECK(result.location() == location);
     DCHECK(result.initialization_flag() == init_flag);
     DCHECK(result.maybe_assigned_flag() == maybe_assigned_flag);
     DCHECK(result.index() + kNotFound == slot_index);