[builtins] Move non-i18n String case conversion functions to C++

src/runtime/runtime-strings.cc

Index: src/runtime/runtime-strings.cc
diff --git a/src/runtime/runtime-strings.cc b/src/runtime/runtime-strings.cc
index e9f11741e9cbeaa9ff0d8056442fd7bf778f5233..3a435913e35b15f2f8dfbd4eafe9800737f62f50 100644
--- a/src/runtime/runtime-strings.cc
+++ b/src/runtime/runtime-strings.cc
@@ -10,7 +10,6 @@
 #include "src/objects-inl.h"
 #include "src/regexp/jsregexp-inl.h"
 #include "src/string-builder.h"
-#include "src/string-case.h"
 #include "src/string-search.h"
 
 namespace v8 {
@@ -633,182 +632,6 @@ RUNTIME_FUNCTION(Runtime_StringToArray) {
 }
 
 
-static inline bool ToUpperOverflows(uc32 character) {
-  // y with umlauts and the micro sign are the only characters that stop
-  // fitting into one-byte when converting to uppercase.
-  static const uc32 yuml_code = 0xff;
-  static const uc32 micro_code = 0xb5;
-  return (character == yuml_code || character == micro_code);
-}
-
-
-template <class Converter>
-MUST_USE_RESULT static Object* ConvertCaseHelper(
-    Isolate* isolate, String* string, SeqString* result, int result_length,
-    unibrow::Mapping<Converter, 128>* mapping) {
-  DisallowHeapAllocation no_gc;
-  // We try this twice, once with the assumption that the result is no longer
-  // than the input and, if that assumption breaks, again with the exact
-  // length.  This may not be pretty, but it is nicer than what was here before
-  // and I hereby claim my vaffel-is.
-  //
-  // NOTE: This assumes that the upper/lower case of an ASCII
-  // character is also ASCII.  This is currently the case, but it
-  // might break in the future if we implement more context and locale
-  // dependent upper/lower conversions.
-  bool has_changed_character = false;
-
-  // Convert all characters to upper case, assuming that they will fit
-  // in the buffer
-  StringCharacterStream stream(string);
-  unibrow::uchar chars[Converter::kMaxWidth];
-  // We can assume that the string is not empty
-  uc32 current = stream.GetNext();
-  bool ignore_overflow = Converter::kIsToLower || result->IsSeqTwoByteString();
-  for (int i = 0; i < result_length;) {
-    bool has_next = stream.HasMore();
-    uc32 next = has_next ? stream.GetNext() : 0;
-    int char_length = mapping->get(current, next, chars);
-    if (char_length == 0) {
-      // The case conversion of this character is the character itself.
-      result->Set(i, current);
-      i++;
-    } else if (char_length == 1 &&
-               (ignore_overflow || !ToUpperOverflows(current))) {
-      // Common case: converting the letter resulted in one character.
-      DCHECK(static_cast<uc32>(chars[0]) != current);
-      result->Set(i, chars[0]);
-      has_changed_character = true;
-      i++;
-    } else if (result_length == string->length()) {
-      bool overflows = ToUpperOverflows(current);
-      // We've assumed that the result would be as long as the
-      // input but here is a character that converts to several
-      // characters.  No matter, we calculate the exact length
-      // of the result and try the whole thing again.
-      //
-      // Note that this leaves room for optimization.  We could just
-      // memcpy what we already have to the result string.  Also,
-      // the result string is the last object allocated we could
-      // "realloc" it and probably, in the vast majority of cases,
-      // extend the existing string to be able to hold the full
-      // result.
-      int next_length = 0;
-      if (has_next) {
-        next_length = mapping->get(next, 0, chars);
-        if (next_length == 0) next_length = 1;
-      }
-      int current_length = i + char_length + next_length;
-      while (stream.HasMore()) {
-        current = stream.GetNext();
-        overflows |= ToUpperOverflows(current);
-        // NOTE: we use 0 as the next character here because, while
-        // the next character may affect what a character converts to,
-        // it does not in any case affect the length of what it convert
-        // to.
-        int char_length = mapping->get(current, 0, chars);
-        if (char_length == 0) char_length = 1;
-        current_length += char_length;
-        if (current_length > String::kMaxLength) {
-          AllowHeapAllocation allocate_error_and_return;
-          THROW_NEW_ERROR_RETURN_FAILURE(isolate,
-                                         NewInvalidStringLengthError());
-        }
-      }
-      // Try again with the real length.  Return signed if we need
-      // to allocate a two-byte string for to uppercase.
-      return (overflows && !ignore_overflow) ? Smi::FromInt(-current_length)
-                                             : Smi::FromInt(current_length);
-    } else {
-      for (int j = 0; j < char_length; j++) {
-        result->Set(i, chars[j]);
-        i++;
-      }
-      has_changed_character = true;
-    }
-    current = next;
-  }
-  if (has_changed_character) {
-    return result;
-  } else {
-    // If we didn't actually change anything in doing the conversion
-    // we simple return the result and let the converted string
-    // become garbage; there is no reason to keep two identical strings
-    // alive.
-    return string;
-  }
-}
-
-template <class Converter>
-MUST_USE_RESULT static Object* ConvertCase(
-    Handle<String> s, Isolate* isolate,
-    unibrow::Mapping<Converter, 128>* mapping) {
-  s = String::Flatten(s);
-  int length = s->length();
-  // Assume that the string is not empty; we need this assumption later
-  if (length == 0) return *s;
-
-  // Simpler handling of ASCII strings.
-  //
-  // NOTE: This assumes that the upper/lower case of an ASCII
-  // character is also ASCII.  This is currently the case, but it
-  // might break in the future if we implement more context and locale
-  // dependent upper/lower conversions.
-  if (s->IsOneByteRepresentationUnderneath()) {
-    // Same length as input.
-    Handle<SeqOneByteString> result =
-        isolate->factory()->NewRawOneByteString(length).ToHandleChecked();
-    DisallowHeapAllocation no_gc;
-    String::FlatContent flat_content = s->GetFlatContent();
-    DCHECK(flat_content.IsFlat());
-    bool has_changed_character = false;
-    int index_to_first_unprocessed = FastAsciiConvert<Converter::kIsToLower>(
-        reinterpret_cast<char*>(result->GetChars()),
-        reinterpret_cast<const char*>(flat_content.ToOneByteVector().start()),
-        length, &has_changed_character);
-    // If not ASCII, we discard the result and take the 2 byte path.
-    if (index_to_first_unprocessed == length)
-      return has_changed_character ? *result : *s;
-  }
-
-  Handle<SeqString> result;  // Same length as input.
-  if (s->IsOneByteRepresentation()) {
-    result = isolate->factory()->NewRawOneByteString(length).ToHandleChecked();
-  } else {
-    result = isolate->factory()->NewRawTwoByteString(length).ToHandleChecked();
-  }
-
-  Object* answer = ConvertCaseHelper(isolate, *s, *result, length, mapping);
-  if (answer->IsException(isolate) || answer->IsString()) return answer;
-
-  DCHECK(answer->IsSmi());
-  length = Smi::cast(answer)->value();
-  if (s->IsOneByteRepresentation() && length > 0) {
-    ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
-        isolate, result, isolate->factory()->NewRawOneByteString(length));
-  } else {
-    if (length < 0) length = -length;
-    ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
-        isolate, result, isolate->factory()->NewRawTwoByteString(length));
-  }
-  return ConvertCaseHelper(isolate, *s, *result, length, mapping);
-}
-
-
-RUNTIME_FUNCTION(Runtime_StringToLowerCase) {
-  HandleScope scope(isolate);
-  DCHECK_EQ(args.length(), 1);
-  CONVERT_ARG_HANDLE_CHECKED(String, s, 0);
-  return ConvertCase(s, isolate, isolate->runtime_state()->to_lower_mapping());
-}
-
-RUNTIME_FUNCTION(Runtime_StringToUpperCase) {
-  HandleScope scope(isolate);
-  DCHECK_EQ(args.length(), 1);
-  CONVERT_ARG_HANDLE_CHECKED(String, s, 0);
-  return ConvertCase(s, isolate, isolate->runtime_state()->to_upper_mapping());
-}
-
 RUNTIME_FUNCTION(Runtime_StringLessThan) {
   HandleScope handle_scope(isolate);
   DCHECK_EQ(2, args.length());