Make TemplateLiteral hashing algorithm more memory efficient

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 6704 matching lines @@
   running_hash += (running_hash << 3);
   running_hash ^= (running_hash >> 11);
   running_hash += (running_hash << 15);
   if ((running_hash & String::kHashBitMask) == 0) {
     return kZeroHash;
   }
   return running_hash;
 }
 
 
+uint32_t StringHasher::ComputeRunningHash(uint32_t running_hash,
+                                          const uc16* chars, int length) {
+  DCHECK(chars && length > 0);

[Dmitry Lomov (no reviews), 2014/11/27 07:23:05]

Style nit: chars != nullptr.

Why 'length > 0', not 'length >= 0'?

[caitp (gmail), 2014/11/27 14:44:49]

Well there's no harm in it being an empty loop, but that path wouldn't be taken
as WriteUtf16() asserts that length > 0, I thought it would be good to keep the
assertions similar.

Done

+  for (int i = 0; i < length; ++i) {
+    running_hash = AddCharacterCore(running_hash, *chars++);
+  }
+  return running_hash;
+}
+
+
+uint32_t StringHasher::ComputeRunningHashOneByte(uint32_t running_hash,
+                                                 const char* chars,
+                                                 int length) {
+  DCHECK(chars && length > 0);

[Dmitry Lomov (no reviews), 2014/11/27 07:23:05]

Ditto

+  for (int i = 0; i < length; ++i) {
+    uint16_t c = static_cast<uint16_t>(*chars++);
+    running_hash = AddCharacterCore(running_hash, c);
+  }
+  return running_hash;
+}
+
+
 void StringHasher::AddCharacter(uint16_t c) {
   // Use the Jenkins one-at-a-time hash function to update the hash
   // for the given character.
   raw_running_hash_ = AddCharacterCore(raw_running_hash_, c);
 }
 
 
 bool StringHasher::UpdateIndex(uint16_t c) {
   DCHECK(is_array_index_);
   if (c < '0' || c > '9') {
@@ skipping 739 matching lines @@
 #undef READ_SHORT_FIELD
 #undef WRITE_SHORT_FIELD
 #undef READ_BYTE_FIELD
 #undef WRITE_BYTE_FIELD
 #undef NOBARRIER_READ_BYTE_FIELD
 #undef NOBARRIER_WRITE_BYTE_FIELD
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_INL_H_