Revert "Handlify concat string and substring."

src/factory.cc

Index: src/factory.cc
diff --git a/src/factory.cc b/src/factory.cc
index f131e508abdd850f5996e7608237a50c9ac603f9..cccc3e76297b20a2ade4272efcd978e7d0c2f06b 100644
--- a/src/factory.cc
+++ b/src/factory.cc
@@ -287,43 +287,11 @@ Handle<SeqTwoByteString> Factory::NewRawTwoByteString(int length,
 }
 
 
-// Returns true for a character in a range.  Both limits are inclusive.
-static inline bool Between(uint32_t character, uint32_t from, uint32_t to) {
-  // This makes uses of the the unsigned wraparound.
-  return character - from <= to - from;
-}
-
-
-static inline Handle<String> MakeOrFindTwoCharacterString(Isolate* isolate,
-                                                          uint16_t c1,
-                                                          uint16_t c2) {
-  // Numeric strings have a different hash algorithm not known by
-  // LookupTwoCharsStringIfExists, so we skip this step for such strings.
-  if (!Between(c1, '0', '9') || !Between(c2, '0', '9')) {
-    String* result;
-    StringTable* table = isolate->heap()->string_table();
-    if (table->LookupTwoCharsStringIfExists(c1, c2, &result)) {
-      return handle(result);
-    }
-  }
-
-  // Now we know the length is 2, we might as well make use of that fact
-  // when building the new string.
-  if (static_cast<unsigned>(c1 | c2) <= String::kMaxOneByteCharCodeU) {
-    // We can do this.
-    ASSERT(IsPowerOf2(String::kMaxOneByteCharCodeU + 1));  // because of this.
-    Handle<SeqOneByteString> str = isolate->factory()->NewRawOneByteString(2);
-    uint8_t* dest = str->GetChars();
-    dest[0] = static_cast<uint8_t>(c1);
-    dest[1] = static_cast<uint8_t>(c2);
-    return str;
-  } else {
-    Handle<SeqTwoByteString> str = isolate->factory()->NewRawTwoByteString(2);
-    uc16* dest = str->GetChars();
-    dest[0] = c1;
-    dest[1] = c2;
-    return str;
-  }
+Handle<String> Factory::NewConsString(Handle<String> first,
+                                      Handle<String> second) {
+  CALL_HEAP_FUNCTION(isolate(),
+                     isolate()->heap()->AllocateConsString(*first, *second),
+                     String);
 }
 
 
@@ -339,99 +307,6 @@ Handle<String> ConcatStringContent(Handle<StringType> result,
 }
 
 
-Handle<ConsString> Factory::NewRawConsString(String::Encoding encoding) {
-  Handle<Map> map = (encoding == String::ONE_BYTE_ENCODING)
-      ? cons_ascii_string_map() : cons_string_map();
-  CALL_HEAP_FUNCTION(isolate(),
-                     isolate()->heap()->Allocate(*map, NEW_SPACE),
-                     ConsString);
-}
-
-
-Handle<String> Factory::NewConsString(Handle<String> left,
-                                      Handle<String> right) {
-  int left_length = left->length();
-  if (left_length == 0) return right;
-  int right_length = right->length();
-  if (right_length == 0) return left;
-
-  int length = left_length + right_length;
-
-  if (length == 2) {
-    uint16_t c1 = left->Get(0);
-    uint16_t c2 = right->Get(0);
-    return MakeOrFindTwoCharacterString(isolate(), c1, c2);
-  }
-
-  // Make sure that an out of memory exception is thrown if the length
-  // of the new cons string is too large.
-  if (length > String::kMaxLength || length < 0) {
-    isolate()->context()->mark_out_of_memory();
-    V8::FatalProcessOutOfMemory("String concatenation result too large.");
-    UNREACHABLE();
-    return Handle<String>::null();
-  }
-
-  bool left_is_one_byte = left->IsOneByteRepresentation();
-  bool right_is_one_byte = right->IsOneByteRepresentation();
-  bool is_one_byte = left_is_one_byte && right_is_one_byte;
-  bool is_one_byte_data_in_two_byte_string = false;
-  if (!is_one_byte) {
-    // At least one of the strings uses two-byte representation so we
-    // can't use the fast case code for short ASCII strings below, but
-    // we can try to save memory if all chars actually fit in ASCII.
-    is_one_byte_data_in_two_byte_string =
-        left->HasOnlyOneByteChars() && right->HasOnlyOneByteChars();
-    if (is_one_byte_data_in_two_byte_string) {
-      isolate()->counters()->string_add_runtime_ext_to_ascii()->Increment();
-    }
-  }
-
-  // If the resulting string is small make a flat string.
-  if (length < ConsString::kMinLength) {
-    // Note that neither of the two inputs can be a slice because:
-    STATIC_ASSERT(ConsString::kMinLength <= SlicedString::kMinLength);
-    ASSERT(left->IsFlat());
-    ASSERT(right->IsFlat());
-
-    if (is_one_byte) {
-      Handle<SeqOneByteString> result = NewRawOneByteString(length);
-      DisallowHeapAllocation no_gc;
-      uint8_t* dest = result->GetChars();
-      // Copy left part.
-      const uint8_t* src = left->IsExternalString()
-          ? Handle<ExternalAsciiString>::cast(left)->GetChars()
-          : Handle<SeqOneByteString>::cast(left)->GetChars();
-      for (int i = 0; i < left_length; i++) *dest++ = src[i];
-      // Copy right part.
-      src = right->IsExternalString()
-          ? Handle<ExternalAsciiString>::cast(right)->GetChars()
-          : Handle<SeqOneByteString>::cast(right)->GetChars();
-      for (int i = 0; i < right_length; i++) *dest++ = src[i];
-      return result;
-    }
-
-    return (is_one_byte_data_in_two_byte_string)
-        ? ConcatStringContent<uint8_t>(NewRawOneByteString(length), left, right)
-        : ConcatStringContent<uc16>(NewRawTwoByteString(length), left, right);
-  }
-
-  Handle<ConsString> result = NewRawConsString(
-      (is_one_byte || is_one_byte_data_in_two_byte_string)
-          ? String::ONE_BYTE_ENCODING
-          : String::TWO_BYTE_ENCODING);
-
-  DisallowHeapAllocation no_gc;
-  WriteBarrierMode mode = result->GetWriteBarrierMode(no_gc);
-
-  result->set_hash_field(String::kEmptyHashField);
-  result->set_length(length);
-  result->set_first(*left, mode);
-  result->set_second(*right, mode);
-  return result;
-}
-
-
 Handle<String> Factory::NewFlatConcatString(Handle<String> first,
                                             Handle<String> second) {
   int total_length = first->length() + second->length();
@@ -446,89 +321,22 @@ Handle<String> Factory::NewFlatConcatString(Handle<String> first,
 }
 
 
-Handle<SlicedString> Factory::NewRawSlicedString(String::Encoding encoding) {
-  Handle<Map> map = (encoding == String::ONE_BYTE_ENCODING)
-      ? sliced_ascii_string_map() : sliced_string_map();
+Handle<String> Factory::NewSubString(Handle<String> str,
+                                     int begin,
+                                     int end) {
   CALL_HEAP_FUNCTION(isolate(),
-                     isolate()->heap()->Allocate(*map, NEW_SPACE),
-                     SlicedString);
+                     str->SubString(begin, end),
+                     String);
 }
 
 
 Handle<String> Factory::NewProperSubString(Handle<String> str,
                                            int begin,
                                            int end) {
-#if VERIFY_HEAP
-  if (FLAG_verify_heap) str->StringVerify();
-#endif
   ASSERT(begin > 0 || end < str->length());
-
-  int length = end - begin;
-  if (length <= 0) return empty_string();
-  if (length == 1) {
-    return LookupSingleCharacterStringFromCode(isolate(), str->Get(begin));
-  }
-  if (length == 2) {
-    // Optimization for 2-byte strings often used as keys in a decompression
-    // dictionary.  Check whether we already have the string in the string
-    // table to prevent creation of many unnecessary strings.
-    uint16_t c1 = str->Get(begin);
-    uint16_t c2 = str->Get(begin + 1);
-    return MakeOrFindTwoCharacterString(isolate(), c1, c2);
-  }
-
-  if (!FLAG_string_slices || length < SlicedString::kMinLength) {
-    if (str->IsOneByteRepresentation()) {
-      Handle<SeqOneByteString> result = NewRawOneByteString(length);
-      uint8_t* dest = result->GetChars();
-      DisallowHeapAllocation no_gc;
-      String::WriteToFlat(*str, dest, begin, end);
-      return result;
-    } else {
-      Handle<SeqTwoByteString> result = NewRawTwoByteString(length);
-      uc16* dest = result->GetChars();
-      DisallowHeapAllocation no_gc;
-      String::WriteToFlat(*str, dest, begin, end);
-      return result;
-    }
-  }
-
-  int offset = begin;
-
-  while (str->IsConsString()) {
-    Handle<ConsString> cons = Handle<ConsString>::cast(str);
-    int split = cons->first()->length();
-    if (split <= offset) {
-      // Slice is fully contained in the second part.
-      str = Handle<String>(cons->second(), isolate());
-      offset -= split;  // Adjust for offset.
-      continue;
-    } else if (offset + length <= split) {
-      // Slice is fully contained in the first part.
-      str = Handle<String>(cons->first(), isolate());
-      continue;
-    }
-    break;
-  }
-
-  if (str->IsSlicedString()) {
-    Handle<SlicedString> slice = Handle<SlicedString>::cast(str);
-    str = Handle<String>(slice->parent(), isolate());
-    offset += slice->offset();
-  } else {
-    str = FlattenGetString(str);
-  }
-
-  ASSERT(str->IsSeqString() || str->IsExternalString());
-  Handle<SlicedString> slice = NewRawSlicedString(
-      str->IsOneByteRepresentation() ? String::ONE_BYTE_ENCODING
-                                     : String::TWO_BYTE_ENCODING);
-
-  slice->set_hash_field(String::kEmptyHashField);
-  slice->set_length(length);
-  slice->set_parent(*str);
-  slice->set_offset(offset);
-  return slice;
+  CALL_HEAP_FUNCTION(isolate(),
+                     isolate()->heap()->AllocateSubString(*str, begin, end),
+                     String);
 }