Make TemplateLiteral hashing algorithm more memory efficient

src/objects-inl.h

Index: src/objects-inl.h
diff --git a/src/objects-inl.h b/src/objects-inl.h
index 03aea64736d818f456c748f76a31d583593dc664..fa6d3beb254c2ba15b5d94ba6709ff71970c27a7 100644
--- a/src/objects-inl.h
+++ b/src/objects-inl.h
@@ -6722,6 +6722,28 @@ uint32_t StringHasher::GetHashCore(uint32_t 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.