[runtime] Inline SeqOneByteSubStringKey IsMatch and AsHandle

The performance actually matters to JSON parsing and this improves it by a % or
2.

In the longer run we should probably share the IsMatch implementation in
StringTableKey directly and call a virtual GetBytes on the key implementation.

Change-Id: I838a106f9c8c52f0385057a52a8c0b9141ae025b
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1589977
Commit-Queue: Toon Verwaest <verwaest@chromium.org>
Auto-Submit: Toon Verwaest <verwaest@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61183}

src/objects.cc

@@ -6477,23 +6477,6 @@ class RegExpKey : public HashTableKey {
   Smi flags_;
 };
 
-Handle<String> SeqOneByteSubStringKey::AsHandle(Isolate* isolate) {
-  return isolate->factory()->NewOneByteInternalizedSubString(
-      string_, from_, length_, HashField());
-}
-
-bool SeqOneByteSubStringKey::IsMatch(Object object) {
-  DisallowHeapAllocation no_gc;
-  String string = String::cast(object);
-  if (string.length() != length_) return false;
-  if (string.IsOneByteRepresentation()) {
-    const uint8_t* data = string.GetChars<uint8_t>(no_gc);
-    return CompareChars(string_->GetChars(no_gc) + from_, data, length_) == 0;
-  }
-  const uint16_t* data = string.GetChars<uint16_t>(no_gc);
-  return CompareChars(string_->GetChars(no_gc) + from_, data, length_) == 0;
-}
-
 // InternalizedStringKey carries a string/internalized-string object as key.
 class InternalizedStringKey : public StringTableKey {
  public:

src/objects/string-inl.h

@@ -260,8 +260,22 @@ class SeqOneByteSubStringKey final : public StringTableKey {
 #pragma warning(pop)
 #endif
 
-  bool IsMatch(Object string) override;
-  Handle<String> AsHandle(Isolate* isolate) override;
+  bool IsMatch(Object object) override {
+    DisallowHeapAllocation no_gc;
+    String string = String::cast(object);
+    if (string.length() != length_) return false;
+    if (string.IsOneByteRepresentation()) {
+      const uint8_t* data = string.GetChars<uint8_t>(no_gc);
+      return CompareChars(string_->GetChars(no_gc) + from_, data, length_) == 0;
+    }
+    const uint16_t* data = string.GetChars<uint16_t>(no_gc);
+    return CompareChars(string_->GetChars(no_gc) + from_, data, length_) == 0;
+  }
+
+  Handle<String> AsHandle(Isolate* isolate) override {
+    return isolate->factory()->NewOneByteInternalizedSubString(
+        string_, from_, length_, HashField());
+  }
 
  private:
   Handle<SeqOneByteString> string_;