[runtime] Don't compute the hash for linear search in descriptor array

src/objects-inl.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.
 //
 // Review notes:
 //
 // - The use of macros in these inline functions may seem superfluous
 // but it is absolutely needed to make sure gcc generates optimal
 // code. gcc is not happy when attempting to inline too deep.
 //
@@ skipping 2573 matching lines @@
   if (out_insertion_index != NULL) *out_insertion_index = limit + 1;
   return T::kNotFound;
 }
 
 
 // Perform a linear search in this fixed array. len is the number of entry
 // indices that are valid.
 template <SearchMode search_mode, typename T>
 int LinearSearch(T* array, Name* name, int len, int valid_entries,
                  int* out_insertion_index) {
-  uint32_t hash = name->Hash();
   if (search_mode == ALL_ENTRIES) {
+    uint32_t hash = name->Hash();
     for (int number = 0; number < len; number++) {
       int sorted_index = array->GetSortedKeyIndex(number);
       Name* entry = array->GetKey(sorted_index);
       uint32_t current_hash = entry->Hash();
       if (current_hash > hash) {
         if (out_insertion_index != NULL) *out_insertion_index = sorted_index;
         return T::kNotFound;
       }
       if (current_hash == hash && entry->Equals(name)) return sorted_index;
     }
     if (out_insertion_index != NULL) *out_insertion_index = len;
     return T::kNotFound;
   } else {
     DCHECK(len >= valid_entries);
     DCHECK_NULL(out_insertion_index);  // Not supported here.
     for (int number = 0; number < valid_entries; number++) {
-      Name* entry = array->GetKey(number);
-      uint32_t current_hash = entry->Hash();
-      if (current_hash == hash && entry->Equals(name)) return number;
+      if (array->GetKey(number)->Equals(name)) return number;
     }
     return T::kNotFound;
   }
 }
 
 
 template <SearchMode search_mode, typename T>
 int Search(T* array, Name* name, int valid_entries, int* out_insertion_index) {
   if (search_mode == VALID_ENTRIES) {
     SLOW_DCHECK(array->IsSortedNoDuplicates(valid_entries));
@@ skipping 5050 matching lines @@
 #undef WRITE_INT64_FIELD
 #undef READ_BYTE_FIELD
 #undef WRITE_BYTE_FIELD
 #undef NOBARRIER_READ_BYTE_FIELD
 #undef NOBARRIER_WRITE_BYTE_FIELD
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_OBJECTS_INL_H_