Improve String handling in Dart for native platforms

[eugenechyrski]

Current implementation of string handling in dart is sub optimal: StringBaseSubstringMatches can be improved to utilize simd instructions. I created simple test utilizing stringzilla library for OneByteStrings and got results showing that performance of indexOf operation can be improved up to 10 times.

dart version 3.5.0-edge.a479f91e80875dd6661b12108c9b81bdaeb2af65

What has been done:

I added another method into String class .String indexOfStrinzilla(String other);

3.string_path.dart has been modified as well

  u/pragma("vm:external-name", "String_indexOfStrinzilla")
  external String indexOfStrinzilla(String other);

4. In c part : string.cc

DEFINE_NATIVE_ENTRY(String_indexOfStrinzilla, 0, 2) {
  const String& receiver =
      String::CheckedHandle(zone, arguments->NativeArgAt(0));
  ASSERT(!receiver.IsNull());
  GET_NON_NULL_NATIVE_ARGUMENT(String, b, arguments->NativeArgAt(1));
  return String::StringZillaTest(receiver,b);
}

5. In bootstrap_natives.h

V(String_indexOfStrinzilla, 2)

6. In object.cc

   
   StringPtr String::StringZillaTest(const String& str,const String& str2, Heap::Space space) {
   
   if (str.IsOneByteString()) {
   
   sz::string_view source = sz::string_view(reinterpret_cast<const char*>(OneByteString::CharAddr(str, 0)));
   sz::string_view target = sz::string_view(reinterpret_cast<const char*>(OneByteString::CharAddr(str2, 0)));
   source.find_last_of(target) ;
   
   }else{
    std::cout << "called to StringZillaTest two byte string" << std::endl;
   }

 return  str.ptr();
}
7. Test dart script:

void main(List

[kyrill007]

These are impressive performance gains that could be achieved with such a small change. It would be good to add this fix and not ignore it.