Tentative implementation of string slices (hidden under the flag --string-slices).

src/regexp-macro-assembler.cc

 // Copyright 2008 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 56 matching lines @@
 #ifdef V8_TARGET_CAN_READ_UNALIGNED
   return !slow_safe();
 #else
   return false;
 #endif
 }
 
 const byte* NativeRegExpMacroAssembler::StringCharacterPosition(
     String* subject,
     int start_index) {
+  // Unpack sliced string.
+  if (subject->IsSlicedString()) {
+     SlicedString* slice = SlicedString::cast(subject);
+     subject = slice->parent();
+     start_index += slice->offset();
+  }
   // Not just flat, but ultra flat.
   ASSERT(subject->IsExternalString() || subject->IsSeqString());
   ASSERT(start_index >= 0);
   ASSERT(start_index <= subject->length());
   if (subject->IsAsciiRepresentation()) {
     const byte* address;
     if (StringShape(subject).IsExternal()) {
       const char* data = ExternalAsciiString::cast(subject)->resource()->data();
       address = reinterpret_cast<const byte*>(data);
     } else {
@@ skipping 36 matching lines @@
   int end_offset = subject_ptr->length();
 
   // The string has been flattened, so it it is a cons string it contains the
   // full string in the first part.
   if (StringShape(subject_ptr).IsCons()) {
     ASSERT_EQ(0, ConsString::cast(subject_ptr)->second()->length());
     subject_ptr = ConsString::cast(subject_ptr)->first();
   }
   // Ensure that an underlying string has the same ascii-ness.
   bool is_ascii = subject_ptr->IsAsciiRepresentation();
-  ASSERT(subject_ptr->IsExternalString() || subject_ptr->IsSeqString());
+  ASSERT(subject_ptr->IsExternalString() ||
+         subject_ptr->IsSeqString() ||
+         subject_ptr->IsSlicedString());
   // String is now either Sequential or External
   int char_size_shift = is_ascii ? 0 : 1;
   int char_length = end_offset - start_offset;
 
   const byte* input_start =
       StringCharacterPosition(subject_ptr, start_offset);
   int byte_length = char_length << char_size_shift;
   const byte* input_end = input_start + byte_length;
   Result res = Execute(*regexp_code,
                        subject_ptr,
@@ skipping 114 matching lines @@
     return NULL;
   }
   *stack_base = new_stack_base;
   intptr_t stack_content_size = old_stack_base - stack_pointer;
   return new_stack_base - stack_content_size;
 }
 
 #endif  // V8_INTERPRETED_REGEXP
 
 } }  // namespace v8::internal