Move string-related runtime functions into separate files.

src/runtime/runtime-regexp.cc

Index: src/runtime/runtime-regexp.cc
diff --git a/src/runtime/runtime-regexp.cc b/src/runtime/runtime-regexp.cc
new file mode 100644
index 0000000000000000000000000000000000000000..e96d50195a80aaa8233ed3da9b89282bfd0aa469
--- /dev/null
+++ b/src/runtime/runtime-regexp.cc
@@ -0,0 +1,1131 @@
+// Copyright 2014 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "src/v8.h"
+
+#include "src/arguments.h"
+#include "src/jsregexp-inl.h"
+#include "src/jsregexp.h"
+#include "src/runtime/runtime.h"
+#include "src/runtime/runtime-utils.h"
+#include "src/runtime/string-builder.h"
+#include "src/string-search.h"
+
+namespace v8 {
+namespace internal {
+
+class CompiledReplacement {
+ public:
+  explicit CompiledReplacement(Zone* zone)
+      : parts_(1, zone), replacement_substrings_(0, zone), zone_(zone) {}
+
+  // Return whether the replacement is simple.
+  bool Compile(Handle<String> replacement, int capture_count,
+               int subject_length);
+
+  // Use Apply only if Compile returned false.
+  void Apply(ReplacementStringBuilder* builder, int match_from, int match_to,
+             int32_t* match);
+
+  // Number of distinct parts of the replacement pattern.
+  int parts() { return parts_.length(); }
+
+  Zone* zone() const { return zone_; }
+
+ private:
+  enum PartType {
+    SUBJECT_PREFIX = 1,
+    SUBJECT_SUFFIX,
+    SUBJECT_CAPTURE,
+    REPLACEMENT_SUBSTRING,
+    REPLACEMENT_STRING,
+    NUMBER_OF_PART_TYPES
+  };
+
+  struct ReplacementPart {
+    static inline ReplacementPart SubjectMatch() {
+      return ReplacementPart(SUBJECT_CAPTURE, 0);
+    }
+    static inline ReplacementPart SubjectCapture(int capture_index) {
+      return ReplacementPart(SUBJECT_CAPTURE, capture_index);
+    }
+    static inline ReplacementPart SubjectPrefix() {
+      return ReplacementPart(SUBJECT_PREFIX, 0);
+    }
+    static inline ReplacementPart SubjectSuffix(int subject_length) {
+      return ReplacementPart(SUBJECT_SUFFIX, subject_length);
+    }
+    static inline ReplacementPart ReplacementString() {
+      return ReplacementPart(REPLACEMENT_STRING, 0);
+    }
+    static inline ReplacementPart ReplacementSubString(int from, int to) {
+      DCHECK(from >= 0);
+      DCHECK(to > from);
+      return ReplacementPart(-from, to);
+    }
+
+    // If tag <= 0 then it is the negation of a start index of a substring of
+    // the replacement pattern, otherwise it's a value from PartType.
+    ReplacementPart(int tag, int data) : tag(tag), data(data) {
+      // Must be non-positive or a PartType value.
+      DCHECK(tag < NUMBER_OF_PART_TYPES);
+    }
+    // Either a value of PartType or a non-positive number that is
+    // the negation of an index into the replacement string.
+    int tag;
+    // The data value's interpretation depends on the value of tag:
+    // tag == SUBJECT_PREFIX ||
+    // tag == SUBJECT_SUFFIX:  data is unused.
+    // tag == SUBJECT_CAPTURE: data is the number of the capture.
+    // tag == REPLACEMENT_SUBSTRING ||
+    // tag == REPLACEMENT_STRING:    data is index into array of substrings
+    //                               of the replacement string.
+    // tag <= 0: Temporary representation of the substring of the replacement
+    //           string ranging over -tag .. data.
+    //           Is replaced by REPLACEMENT_{SUB,}STRING when we create the
+    //           substring objects.
+    int data;
+  };
+
+  template <typename Char>
+  bool ParseReplacementPattern(ZoneList<ReplacementPart>* parts,
+                               Vector<Char> characters, int capture_count,
+                               int subject_length, Zone* zone) {
+    int length = characters.length();
+    int last = 0;
+    for (int i = 0; i < length; i++) {
+      Char c = characters[i];
+      if (c == '$') {
+        int next_index = i + 1;
+        if (next_index == length) {  // No next character!
+          break;
+        }
+        Char c2 = characters[next_index];
+        switch (c2) {
+          case '$':
+            if (i > last) {
+              // There is a substring before. Include the first "$".
+              parts->Add(
+                  ReplacementPart::ReplacementSubString(last, next_index),
+                  zone);
+              last = next_index + 1;  // Continue after the second "$".
+            } else {
+              // Let the next substring start with the second "$".
+              last = next_index;
+            }
+            i = next_index;
+            break;
+          case '`':
+            if (i > last) {
+              parts->Add(ReplacementPart::ReplacementSubString(last, i), zone);
+            }
+            parts->Add(ReplacementPart::SubjectPrefix(), zone);
+            i = next_index;
+            last = i + 1;
+            break;
+          case '\'':
+            if (i > last) {
+              parts->Add(ReplacementPart::ReplacementSubString(last, i), zone);
+            }
+            parts->Add(ReplacementPart::SubjectSuffix(subject_length), zone);
+            i = next_index;
+            last = i + 1;
+            break;
+          case '&':
+            if (i > last) {
+              parts->Add(ReplacementPart::ReplacementSubString(last, i), zone);
+            }
+            parts->Add(ReplacementPart::SubjectMatch(), zone);
+            i = next_index;
+            last = i + 1;
+            break;
+          case '0':
+          case '1':
+          case '2':
+          case '3':
+          case '4':
+          case '5':
+          case '6':
+          case '7':
+          case '8':
+          case '9': {
+            int capture_ref = c2 - '0';
+            if (capture_ref > capture_count) {
+              i = next_index;
+              continue;
+            }
+            int second_digit_index = next_index + 1;
+            if (second_digit_index < length) {
+              // Peek ahead to see if we have two digits.
+              Char c3 = characters[second_digit_index];
+              if ('0' <= c3 && c3 <= '9') {  // Double digits.
+                int double_digit_ref = capture_ref * 10 + c3 - '0';
+                if (double_digit_ref <= capture_count) {
+                  next_index = second_digit_index;
+                  capture_ref = double_digit_ref;
+                }
+              }
+            }
+            if (capture_ref > 0) {
+              if (i > last) {
+                parts->Add(ReplacementPart::ReplacementSubString(last, i),
+                           zone);
+              }
+              DCHECK(capture_ref <= capture_count);
+              parts->Add(ReplacementPart::SubjectCapture(capture_ref), zone);
+              last = next_index + 1;
+            }
+            i = next_index;
+            break;
+          }
+          default:
+            i = next_index;
+            break;
+        }
+      }
+    }
+    if (length > last) {
+      if (last == 0) {
+        // Replacement is simple.  Do not use Apply to do the replacement.
+        return true;
+      } else {
+        parts->Add(ReplacementPart::ReplacementSubString(last, length), zone);
+      }
+    }
+    return false;
+  }
+
+  ZoneList<ReplacementPart> parts_;
+  ZoneList<Handle<String> > replacement_substrings_;
+  Zone* zone_;
+};
+
+
+bool CompiledReplacement::Compile(Handle<String> replacement, int capture_count,
+                                  int subject_length) {
+  {
+    DisallowHeapAllocation no_gc;
+    String::FlatContent content = replacement->GetFlatContent();
+    DCHECK(content.IsFlat());
+    bool simple = false;
+    if (content.IsOneByte()) {
+      simple = ParseReplacementPattern(&parts_, content.ToOneByteVector(),
+                                       capture_count, subject_length, zone());
+    } else {
+      DCHECK(content.IsTwoByte());
+      simple = ParseReplacementPattern(&parts_, content.ToUC16Vector(),
+                                       capture_count, subject_length, zone());
+    }
+    if (simple) return true;
+  }
+
+  Isolate* isolate = replacement->GetIsolate();
+  // Find substrings of replacement string and create them as String objects.
+  int substring_index = 0;
+  for (int i = 0, n = parts_.length(); i < n; i++) {
+    int tag = parts_[i].tag;
+    if (tag <= 0) {  // A replacement string slice.
+      int from = -tag;
+      int to = parts_[i].data;
+      replacement_substrings_.Add(
+          isolate->factory()->NewSubString(replacement, from, to), zone());
+      parts_[i].tag = REPLACEMENT_SUBSTRING;
+      parts_[i].data = substring_index;
+      substring_index++;
+    } else if (tag == REPLACEMENT_STRING) {
+      replacement_substrings_.Add(replacement, zone());
+      parts_[i].data = substring_index;
+      substring_index++;
+    }
+  }
+  return false;
+}
+
+
+void CompiledReplacement::Apply(ReplacementStringBuilder* builder,
+                                int match_from, int match_to, int32_t* match) {
+  DCHECK_LT(0, parts_.length());
+  for (int i = 0, n = parts_.length(); i < n; i++) {
+    ReplacementPart part = parts_[i];
+    switch (part.tag) {
+      case SUBJECT_PREFIX:
+        if (match_from > 0) builder->AddSubjectSlice(0, match_from);
+        break;
+      case SUBJECT_SUFFIX: {
+        int subject_length = part.data;
+        if (match_to < subject_length) {
+          builder->AddSubjectSlice(match_to, subject_length);
+        }
+        break;
+      }
+      case SUBJECT_CAPTURE: {
+        int capture = part.data;
+        int from = match[capture * 2];
+        int to = match[capture * 2 + 1];
+        if (from >= 0 && to > from) {
+          builder->AddSubjectSlice(from, to);
+        }
+        break;
+      }
+      case REPLACEMENT_SUBSTRING:
+      case REPLACEMENT_STRING:
+        builder->AddString(replacement_substrings_[part.data]);
+        break;
+      default:
+        UNREACHABLE();
+    }
+  }
+}
+
+
+void FindOneByteStringIndices(Vector<const uint8_t> subject, char pattern,
+                              ZoneList<int>* indices, unsigned int limit,
+                              Zone* zone) {
+  DCHECK(limit > 0);
+  // Collect indices of pattern in subject using memchr.
+  // Stop after finding at most limit values.
+  const uint8_t* subject_start = subject.start();
+  const uint8_t* subject_end = subject_start + subject.length();
+  const uint8_t* pos = subject_start;
+  while (limit > 0) {
+    pos = reinterpret_cast<const uint8_t*>(
+        memchr(pos, pattern, subject_end - pos));
+    if (pos == NULL) return;
+    indices->Add(static_cast<int>(pos - subject_start), zone);
+    pos++;
+    limit--;
+  }
+}
+
+
+void FindTwoByteStringIndices(const Vector<const uc16> subject, uc16 pattern,
+                              ZoneList<int>* indices, unsigned int limit,
+                              Zone* zone) {
+  DCHECK(limit > 0);
+  const uc16* subject_start = subject.start();
+  const uc16* subject_end = subject_start + subject.length();
+  for (const uc16* pos = subject_start; pos < subject_end && limit > 0; pos++) {
+    if (*pos == pattern) {
+      indices->Add(static_cast<int>(pos - subject_start), zone);
+      limit--;
+    }
+  }
+}
+
+
+template <typename SubjectChar, typename PatternChar>
+void FindStringIndices(Isolate* isolate, Vector<const SubjectChar> subject,
+                       Vector<const PatternChar> pattern,
+                       ZoneList<int>* indices, unsigned int limit, Zone* zone) {
+  DCHECK(limit > 0);
+  // Collect indices of pattern in subject.
+  // Stop after finding at most limit values.
+  int pattern_length = pattern.length();
+  int index = 0;
+  StringSearch<PatternChar, SubjectChar> search(isolate, pattern);
+  while (limit > 0) {
+    index = search.Search(subject, index);
+    if (index < 0) return;
+    indices->Add(index, zone);
+    index += pattern_length;
+    limit--;
+  }
+}
+
+
+void FindStringIndicesDispatch(Isolate* isolate, String* subject,
+                               String* pattern, ZoneList<int>* indices,
+                               unsigned int limit, Zone* zone) {
+  {
+    DisallowHeapAllocation no_gc;
+    String::FlatContent subject_content = subject->GetFlatContent();
+    String::FlatContent pattern_content = pattern->GetFlatContent();
+    DCHECK(subject_content.IsFlat());
+    DCHECK(pattern_content.IsFlat());
+    if (subject_content.IsOneByte()) {
+      Vector<const uint8_t> subject_vector = subject_content.ToOneByteVector();
+      if (pattern_content.IsOneByte()) {
+        Vector<const uint8_t> pattern_vector =
+            pattern_content.ToOneByteVector();
+        if (pattern_vector.length() == 1) {
+          FindOneByteStringIndices(subject_vector, pattern_vector[0], indices,
+                                   limit, zone);
+        } else {
+          FindStringIndices(isolate, subject_vector, pattern_vector, indices,
+                            limit, zone);
+        }
+      } else {
+        FindStringIndices(isolate, subject_vector,
+                          pattern_content.ToUC16Vector(), indices, limit, zone);
+      }
+    } else {
+      Vector<const uc16> subject_vector = subject_content.ToUC16Vector();
+      if (pattern_content.IsOneByte()) {
+        Vector<const uint8_t> pattern_vector =
+            pattern_content.ToOneByteVector();
+        if (pattern_vector.length() == 1) {
+          FindTwoByteStringIndices(subject_vector, pattern_vector[0], indices,
+                                   limit, zone);
+        } else {
+          FindStringIndices(isolate, subject_vector, pattern_vector, indices,
+                            limit, zone);
+        }
+      } else {
+        Vector<const uc16> pattern_vector = pattern_content.ToUC16Vector();
+        if (pattern_vector.length() == 1) {
+          FindTwoByteStringIndices(subject_vector, pattern_vector[0], indices,
+                                   limit, zone);
+        } else {
+          FindStringIndices(isolate, subject_vector, pattern_vector, indices,
+                            limit, zone);
+        }
+      }
+    }
+  }
+}
+
+
+template <typename ResultSeqString>
+MUST_USE_RESULT static Object* StringReplaceGlobalAtomRegExpWithString(
+    Isolate* isolate, Handle<String> subject, Handle<JSRegExp> pattern_regexp,
+    Handle<String> replacement, Handle<JSArray> last_match_info) {
+  DCHECK(subject->IsFlat());
+  DCHECK(replacement->IsFlat());
+
+  ZoneScope zone_scope(isolate->runtime_zone());
+  ZoneList<int> indices(8, zone_scope.zone());
+  DCHECK_EQ(JSRegExp::ATOM, pattern_regexp->TypeTag());
+  String* pattern =
+      String::cast(pattern_regexp->DataAt(JSRegExp::kAtomPatternIndex));
+  int subject_len = subject->length();
+  int pattern_len = pattern->length();
+  int replacement_len = replacement->length();
+
+  FindStringIndicesDispatch(isolate, *subject, pattern, &indices, 0xffffffff,
+                            zone_scope.zone());
+
+  int matches = indices.length();
+  if (matches == 0) return *subject;
+
+  // Detect integer overflow.
+  int64_t result_len_64 = (static_cast<int64_t>(replacement_len) -
+                           static_cast<int64_t>(pattern_len)) *
+                              static_cast<int64_t>(matches) +
+                          static_cast<int64_t>(subject_len);
+  int result_len;
+  if (result_len_64 > static_cast<int64_t>(String::kMaxLength)) {
+    STATIC_ASSERT(String::kMaxLength < kMaxInt);
+    result_len = kMaxInt;  // Provoke exception.
+  } else {
+    result_len = static_cast<int>(result_len_64);
+  }
+
+  int subject_pos = 0;
+  int result_pos = 0;
+
+  MaybeHandle<SeqString> maybe_res;
+  if (ResultSeqString::kHasOneByteEncoding) {
+    maybe_res = isolate->factory()->NewRawOneByteString(result_len);
+  } else {
+    maybe_res = isolate->factory()->NewRawTwoByteString(result_len);
+  }
+  Handle<SeqString> untyped_res;
+  ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, untyped_res, maybe_res);
+  Handle<ResultSeqString> result = Handle<ResultSeqString>::cast(untyped_res);
+
+  for (int i = 0; i < matches; i++) {
+    // Copy non-matched subject content.
+    if (subject_pos < indices.at(i)) {
+      String::WriteToFlat(*subject, result->GetChars() + result_pos,
+                          subject_pos, indices.at(i));
+      result_pos += indices.at(i) - subject_pos;
+    }
+
+    // Replace match.
+    if (replacement_len > 0) {
+      String::WriteToFlat(*replacement, result->GetChars() + result_pos, 0,
+                          replacement_len);
+      result_pos += replacement_len;
+    }
+
+    subject_pos = indices.at(i) + pattern_len;
+  }
+  // Add remaining subject content at the end.
+  if (subject_pos < subject_len) {
+    String::WriteToFlat(*subject, result->GetChars() + result_pos, subject_pos,
+                        subject_len);
+  }
+
+  int32_t match_indices[] = {indices.at(matches - 1),
+                             indices.at(matches - 1) + pattern_len};
+  RegExpImpl::SetLastMatchInfo(last_match_info, subject, 0, match_indices);
+
+  return *result;
+}
+
+
+MUST_USE_RESULT static Object* StringReplaceGlobalRegExpWithString(
+    Isolate* isolate, Handle<String> subject, Handle<JSRegExp> regexp,
+    Handle<String> replacement, Handle<JSArray> last_match_info) {
+  DCHECK(subject->IsFlat());
+  DCHECK(replacement->IsFlat());
+
+  int capture_count = regexp->CaptureCount();
+  int subject_length = subject->length();
+
+  // CompiledReplacement uses zone allocation.
+  ZoneScope zone_scope(isolate->runtime_zone());
+  CompiledReplacement compiled_replacement(zone_scope.zone());
+  bool simple_replace =
+      compiled_replacement.Compile(replacement, capture_count, subject_length);
+
+  // Shortcut for simple non-regexp global replacements
+  if (regexp->TypeTag() == JSRegExp::ATOM && simple_replace) {
+    if (subject->HasOnlyOneByteChars() && replacement->HasOnlyOneByteChars()) {
+      return StringReplaceGlobalAtomRegExpWithString<SeqOneByteString>(
+          isolate, subject, regexp, replacement, last_match_info);
+    } else {
+      return StringReplaceGlobalAtomRegExpWithString<SeqTwoByteString>(
+          isolate, subject, regexp, replacement, last_match_info);
+    }
+  }
+
+  RegExpImpl::GlobalCache global_cache(regexp, subject, true, isolate);
+  if (global_cache.HasException()) return isolate->heap()->exception();
+
+  int32_t* current_match = global_cache.FetchNext();
+  if (current_match == NULL) {
+    if (global_cache.HasException()) return isolate->heap()->exception();
+    return *subject;
+  }
+
+  // Guessing the number of parts that the final result string is built
+  // from. Global regexps can match any number of times, so we guess
+  // conservatively.
+  int expected_parts = (compiled_replacement.parts() + 1) * 4 + 1;
+  ReplacementStringBuilder builder(isolate->heap(), subject, expected_parts);
+
+  // Number of parts added by compiled replacement plus preceeding
+  // string and possibly suffix after last match.  It is possible for
+  // all components to use two elements when encoded as two smis.
+  const int parts_added_per_loop = 2 * (compiled_replacement.parts() + 2);
+
+  int prev = 0;
+
+  do {
+    builder.EnsureCapacity(parts_added_per_loop);
+
+    int start = current_match[0];
+    int end = current_match[1];
+
+    if (prev < start) {
+      builder.AddSubjectSlice(prev, start);
+    }
+
+    if (simple_replace) {
+      builder.AddString(replacement);
+    } else {
+      compiled_replacement.Apply(&builder, start, end, current_match);
+    }
+    prev = end;
+
+    current_match = global_cache.FetchNext();
+  } while (current_match != NULL);
+
+  if (global_cache.HasException()) return isolate->heap()->exception();
+
+  if (prev < subject_length) {
+    builder.EnsureCapacity(2);
+    builder.AddSubjectSlice(prev, subject_length);
+  }
+
+  RegExpImpl::SetLastMatchInfo(last_match_info, subject, capture_count,
+                               global_cache.LastSuccessfulMatch());
+
+  Handle<String> result;
+  ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, result, builder.ToString());
+  return *result;
+}
+
+
+template <typename ResultSeqString>
+MUST_USE_RESULT static Object* StringReplaceGlobalRegExpWithEmptyString(
+    Isolate* isolate, Handle<String> subject, Handle<JSRegExp> regexp,
+    Handle<JSArray> last_match_info) {
+  DCHECK(subject->IsFlat());
+
+  // Shortcut for simple non-regexp global replacements
+  if (regexp->TypeTag() == JSRegExp::ATOM) {
+    Handle<String> empty_string = isolate->factory()->empty_string();
+    if (subject->IsOneByteRepresentation()) {
+      return StringReplaceGlobalAtomRegExpWithString<SeqOneByteString>(
+          isolate, subject, regexp, empty_string, last_match_info);
+    } else {
+      return StringReplaceGlobalAtomRegExpWithString<SeqTwoByteString>(
+          isolate, subject, regexp, empty_string, last_match_info);
+    }
+  }
+
+  RegExpImpl::GlobalCache global_cache(regexp, subject, true, isolate);
+  if (global_cache.HasException()) return isolate->heap()->exception();
+
+  int32_t* current_match = global_cache.FetchNext();
+  if (current_match == NULL) {
+    if (global_cache.HasException()) return isolate->heap()->exception();
+    return *subject;
+  }
+
+  int start = current_match[0];
+  int end = current_match[1];
+  int capture_count = regexp->CaptureCount();
+  int subject_length = subject->length();
+
+  int new_length = subject_length - (end - start);
+  if (new_length == 0) return isolate->heap()->empty_string();
+
+  Handle<ResultSeqString> answer;
+  if (ResultSeqString::kHasOneByteEncoding) {
+    answer = Handle<ResultSeqString>::cast(
+        isolate->factory()->NewRawOneByteString(new_length).ToHandleChecked());
+  } else {
+    answer = Handle<ResultSeqString>::cast(
+        isolate->factory()->NewRawTwoByteString(new_length).ToHandleChecked());
+  }
+
+  int prev = 0;
+  int position = 0;
+
+  do {
+    start = current_match[0];
+    end = current_match[1];
+    if (prev < start) {
+      // Add substring subject[prev;start] to answer string.
+      String::WriteToFlat(*subject, answer->GetChars() + position, prev, start);
+      position += start - prev;
+    }
+    prev = end;
+
+    current_match = global_cache.FetchNext();
+  } while (current_match != NULL);
+
+  if (global_cache.HasException()) return isolate->heap()->exception();
+
+  RegExpImpl::SetLastMatchInfo(last_match_info, subject, capture_count,
+                               global_cache.LastSuccessfulMatch());
+
+  if (prev < subject_length) {
+    // Add substring subject[prev;length] to answer string.
+    String::WriteToFlat(*subject, answer->GetChars() + position, prev,
+                        subject_length);
+    position += subject_length - prev;
+  }
+
+  if (position == 0) return isolate->heap()->empty_string();
+
+  // Shorten string and fill
+  int string_size = ResultSeqString::SizeFor(position);
+  int allocated_string_size = ResultSeqString::SizeFor(new_length);
+  int delta = allocated_string_size - string_size;
+
+  answer->set_length(position);
+  if (delta == 0) return *answer;
+
+  Address end_of_string = answer->address() + string_size;
+  Heap* heap = isolate->heap();
+
+  // The trimming is performed on a newly allocated object, which is on a
+  // fresly allocated page or on an already swept page. Hence, the sweeper
+  // thread can not get confused with the filler creation. No synchronization
+  // needed.
+  heap->CreateFillerObjectAt(end_of_string, delta);
+  heap->AdjustLiveBytes(answer->address(), -delta, Heap::FROM_MUTATOR);
+  return *answer;
+}
+
+
+RUNTIME_FUNCTION(Runtime_StringReplaceGlobalRegExpWithString) {
+  HandleScope scope(isolate);
+  DCHECK(args.length() == 4);
+
+  CONVERT_ARG_HANDLE_CHECKED(String, subject, 0);
+  CONVERT_ARG_HANDLE_CHECKED(String, replacement, 2);
+  CONVERT_ARG_HANDLE_CHECKED(JSRegExp, regexp, 1);
+  CONVERT_ARG_HANDLE_CHECKED(JSArray, last_match_info, 3);
+
+  RUNTIME_ASSERT(regexp->GetFlags().is_global());
+  RUNTIME_ASSERT(last_match_info->HasFastObjectElements());
+
+  subject = String::Flatten(subject);
+
+  if (replacement->length() == 0) {
+    if (subject->HasOnlyOneByteChars()) {
+      return StringReplaceGlobalRegExpWithEmptyString<SeqOneByteString>(
+          isolate, subject, regexp, last_match_info);
+    } else {
+      return StringReplaceGlobalRegExpWithEmptyString<SeqTwoByteString>(
+          isolate, subject, regexp, last_match_info);
+    }
+  }
+
+  replacement = String::Flatten(replacement);
+
+  return StringReplaceGlobalRegExpWithString(isolate, subject, regexp,
+                                             replacement, last_match_info);
+}
+
+
+RUNTIME_FUNCTION(Runtime_StringSplit) {
+  HandleScope handle_scope(isolate);
+  DCHECK(args.length() == 3);
+  CONVERT_ARG_HANDLE_CHECKED(String, subject, 0);
+  CONVERT_ARG_HANDLE_CHECKED(String, pattern, 1);
+  CONVERT_NUMBER_CHECKED(uint32_t, limit, Uint32, args[2]);
+  RUNTIME_ASSERT(limit > 0);
+
+  int subject_length = subject->length();
+  int pattern_length = pattern->length();
+  RUNTIME_ASSERT(pattern_length > 0);
+
+  if (limit == 0xffffffffu) {
+    Handle<Object> cached_answer(
+        RegExpResultsCache::Lookup(isolate->heap(), *subject, *pattern,
+                                   RegExpResultsCache::STRING_SPLIT_SUBSTRINGS),
+        isolate);
+    if (*cached_answer != Smi::FromInt(0)) {
+      // The cache FixedArray is a COW-array and can therefore be reused.
+      Handle<JSArray> result = isolate->factory()->NewJSArrayWithElements(
+          Handle<FixedArray>::cast(cached_answer));
+      return *result;
+    }
+  }
+
+  // The limit can be very large (0xffffffffu), but since the pattern
+  // isn't empty, we can never create more parts than ~half the length
+  // of the subject.
+
+  subject = String::Flatten(subject);
+  pattern = String::Flatten(pattern);
+
+  static const int kMaxInitialListCapacity = 16;
+
+  ZoneScope zone_scope(isolate->runtime_zone());
+
+  // Find (up to limit) indices of separator and end-of-string in subject
+  int initial_capacity = Min<uint32_t>(kMaxInitialListCapacity, limit);
+  ZoneList<int> indices(initial_capacity, zone_scope.zone());
+
+  FindStringIndicesDispatch(isolate, *subject, *pattern, &indices, limit,
+                            zone_scope.zone());
+
+  if (static_cast<uint32_t>(indices.length()) < limit) {
+    indices.Add(subject_length, zone_scope.zone());
+  }
+
+  // The list indices now contains the end of each part to create.
+
+  // Create JSArray of substrings separated by separator.
+  int part_count = indices.length();
+
+  Handle<JSArray> result = isolate->factory()->NewJSArray(part_count);
+  JSObject::EnsureCanContainHeapObjectElements(result);
+  result->set_length(Smi::FromInt(part_count));
+
+  DCHECK(result->HasFastObjectElements());
+
+  if (part_count == 1 && indices.at(0) == subject_length) {
+    FixedArray::cast(result->elements())->set(0, *subject);
+    return *result;
+  }
+
+  Handle<FixedArray> elements(FixedArray::cast(result->elements()));
+  int part_start = 0;
+  for (int i = 0; i < part_count; i++) {
+    HandleScope local_loop_handle(isolate);
+    int part_end = indices.at(i);
+    Handle<String> substring =
+        isolate->factory()->NewProperSubString(subject, part_start, part_end);
+    elements->set(i, *substring);
+    part_start = part_end + pattern_length;
+  }
+
+  if (limit == 0xffffffffu) {
+    if (result->HasFastObjectElements()) {
+      RegExpResultsCache::Enter(isolate, subject, pattern, elements,
+                                RegExpResultsCache::STRING_SPLIT_SUBSTRINGS);
+    }
+  }
+
+  return *result;
+}
+
+
+RUNTIME_FUNCTION(Runtime_RegExpCompile) {
+  HandleScope scope(isolate);
+  DCHECK(args.length() == 3);
+  CONVERT_ARG_HANDLE_CHECKED(JSRegExp, re, 0);
+  CONVERT_ARG_HANDLE_CHECKED(String, pattern, 1);
+  CONVERT_ARG_HANDLE_CHECKED(String, flags, 2);
+  Handle<Object> result;
+  ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, result,
+                                     RegExpImpl::Compile(re, pattern, flags));
+  return *result;
+}
+
+
+RUNTIME_FUNCTION(Runtime_RegExpExecRT) {
+  HandleScope scope(isolate);
+  DCHECK(args.length() == 4);
+  CONVERT_ARG_HANDLE_CHECKED(JSRegExp, regexp, 0);
+  CONVERT_ARG_HANDLE_CHECKED(String, subject, 1);
+  CONVERT_INT32_ARG_CHECKED(index, 2);
+  CONVERT_ARG_HANDLE_CHECKED(JSArray, last_match_info, 3);
+  // Due to the way the JS calls are constructed this must be less than the
+  // length of a string, i.e. it is always a Smi.  We check anyway for security.
+  RUNTIME_ASSERT(index >= 0);
+  RUNTIME_ASSERT(index <= subject->length());
+  isolate->counters()->regexp_entry_runtime()->Increment();
+  Handle<Object> result;
+  ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
+      isolate, result,
+      RegExpImpl::Exec(regexp, subject, index, last_match_info));
+  return *result;
+}
+
+
+RUNTIME_FUNCTION(Runtime_RegExpConstructResult) {
+  HandleScope handle_scope(isolate);
+  DCHECK(args.length() == 3);
+  CONVERT_SMI_ARG_CHECKED(size, 0);
+  RUNTIME_ASSERT(size >= 0 && size <= FixedArray::kMaxLength);
+  CONVERT_ARG_HANDLE_CHECKED(Object, index, 1);
+  CONVERT_ARG_HANDLE_CHECKED(Object, input, 2);
+  Handle<FixedArray> elements = isolate->factory()->NewFixedArray(size);
+  Handle<Map> regexp_map(isolate->native_context()->regexp_result_map());
+  Handle<JSObject> object =
+      isolate->factory()->NewJSObjectFromMap(regexp_map, NOT_TENURED, false);
+  Handle<JSArray> array = Handle<JSArray>::cast(object);
+  array->set_elements(*elements);
+  array->set_length(Smi::FromInt(size));
+  // Write in-object properties after the length of the array.
+  array->InObjectPropertyAtPut(JSRegExpResult::kIndexIndex, *index);
+  array->InObjectPropertyAtPut(JSRegExpResult::kInputIndex, *input);
+  return *array;
+}
+
+
+RUNTIME_FUNCTION(Runtime_RegExpInitializeObject) {
+  HandleScope scope(isolate);
+  DCHECK(args.length() == 6);
+  CONVERT_ARG_HANDLE_CHECKED(JSRegExp, regexp, 0);
+  CONVERT_ARG_HANDLE_CHECKED(String, source, 1);
+  // If source is the empty string we set it to "(?:)" instead as
+  // suggested by ECMA-262, 5th, section 15.10.4.1.
+  if (source->length() == 0) source = isolate->factory()->query_colon_string();
+
+  CONVERT_ARG_HANDLE_CHECKED(Object, global, 2);
+  if (!global->IsTrue()) global = isolate->factory()->false_value();
+
+  CONVERT_ARG_HANDLE_CHECKED(Object, ignoreCase, 3);
+  if (!ignoreCase->IsTrue()) ignoreCase = isolate->factory()->false_value();
+
+  CONVERT_ARG_HANDLE_CHECKED(Object, multiline, 4);
+  if (!multiline->IsTrue()) multiline = isolate->factory()->false_value();
+
+  CONVERT_ARG_HANDLE_CHECKED(Object, sticky, 5);
+  if (!sticky->IsTrue()) sticky = isolate->factory()->false_value();
+
+  Map* map = regexp->map();
+  Object* constructor = map->constructor();
+  if (!FLAG_harmony_regexps && constructor->IsJSFunction() &&
+      JSFunction::cast(constructor)->initial_map() == map) {
+    // If we still have the original map, set in-object properties directly.
+    regexp->InObjectPropertyAtPut(JSRegExp::kSourceFieldIndex, *source);
+    // Both true and false are immovable immortal objects so no need for write
+    // barrier.
+    regexp->InObjectPropertyAtPut(JSRegExp::kGlobalFieldIndex, *global,
+                                  SKIP_WRITE_BARRIER);
+    regexp->InObjectPropertyAtPut(JSRegExp::kIgnoreCaseFieldIndex, *ignoreCase,
+                                  SKIP_WRITE_BARRIER);
+    regexp->InObjectPropertyAtPut(JSRegExp::kMultilineFieldIndex, *multiline,
+                                  SKIP_WRITE_BARRIER);
+    regexp->InObjectPropertyAtPut(JSRegExp::kLastIndexFieldIndex,
+                                  Smi::FromInt(0), SKIP_WRITE_BARRIER);
+    return *regexp;
+  }
+
+  // Map has changed, so use generic, but slower, method.  We also end here if
+  // the --harmony-regexp flag is set, because the initial map does not have
+  // space for the 'sticky' flag, since it is from the snapshot, but must work
+  // both with and without --harmony-regexp.  When sticky comes out from under
+  // the flag, we will be able to use the fast initial map.
+  PropertyAttributes final =
+      static_cast<PropertyAttributes>(READ_ONLY | DONT_ENUM | DONT_DELETE);
+  PropertyAttributes writable =
+      static_cast<PropertyAttributes>(DONT_ENUM | DONT_DELETE);
+  Handle<Object> zero(Smi::FromInt(0), isolate);
+  Factory* factory = isolate->factory();
+  JSObject::SetOwnPropertyIgnoreAttributes(regexp, factory->source_string(),
+                                           source, final).Check();
+  JSObject::SetOwnPropertyIgnoreAttributes(regexp, factory->global_string(),
+                                           global, final).Check();
+  JSObject::SetOwnPropertyIgnoreAttributes(
+      regexp, factory->ignore_case_string(), ignoreCase, final).Check();
+  JSObject::SetOwnPropertyIgnoreAttributes(regexp, factory->multiline_string(),
+                                           multiline, final).Check();
+  if (FLAG_harmony_regexps) {
+    JSObject::SetOwnPropertyIgnoreAttributes(regexp, factory->sticky_string(),
+                                             sticky, final).Check();
+  }
+  JSObject::SetOwnPropertyIgnoreAttributes(regexp, factory->last_index_string(),
+                                           zero, writable).Check();
+  return *regexp;
+}
+
+
+RUNTIME_FUNCTION(Runtime_MaterializeRegExpLiteral) {
+  HandleScope scope(isolate);
+  DCHECK(args.length() == 4);
+  CONVERT_ARG_HANDLE_CHECKED(FixedArray, literals, 0);
+  CONVERT_SMI_ARG_CHECKED(index, 1);
+  CONVERT_ARG_HANDLE_CHECKED(String, pattern, 2);
+  CONVERT_ARG_HANDLE_CHECKED(String, flags, 3);
+
+  // Get the RegExp function from the context in the literals array.
+  // This is the RegExp function from the context in which the
+  // function was created.  We do not use the RegExp function from the
+  // current native context because this might be the RegExp function
+  // from another context which we should not have access to.
+  Handle<JSFunction> constructor = Handle<JSFunction>(
+      JSFunction::NativeContextFromLiterals(*literals)->regexp_function());
+  // Compute the regular expression literal.
+  Handle<Object> regexp;
+  ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
+      isolate, regexp,
+      RegExpImpl::CreateRegExpLiteral(constructor, pattern, flags));
+  literals->set(index, *regexp);
+  return *regexp;
+}
+
+
+// Only called from Runtime_RegExpExecMultiple so it doesn't need to maintain
+// separate last match info.  See comment on that function.
+template <bool has_capture>
+static Object* SearchRegExpMultiple(Isolate* isolate, Handle<String> subject,
+                                    Handle<JSRegExp> regexp,
+                                    Handle<JSArray> last_match_array,
+                                    Handle<JSArray> result_array) {
+  DCHECK(subject->IsFlat());
+  DCHECK_NE(has_capture, regexp->CaptureCount() == 0);
+
+  int capture_count = regexp->CaptureCount();
+  int subject_length = subject->length();
+
+  static const int kMinLengthToCache = 0x1000;
+
+  if (subject_length > kMinLengthToCache) {
+    Handle<Object> cached_answer(
+        RegExpResultsCache::Lookup(isolate->heap(), *subject, regexp->data(),
+                                   RegExpResultsCache::REGEXP_MULTIPLE_INDICES),
+        isolate);
+    if (*cached_answer != Smi::FromInt(0)) {
+      Handle<FixedArray> cached_fixed_array =
+          Handle<FixedArray>(FixedArray::cast(*cached_answer));
+      // The cache FixedArray is a COW-array and can therefore be reused.
+      JSArray::SetContent(result_array, cached_fixed_array);
+      // The actual length of the result array is stored in the last element of
+      // the backing store (the backing FixedArray may have a larger capacity).
+      Object* cached_fixed_array_last_element =
+          cached_fixed_array->get(cached_fixed_array->length() - 1);
+      Smi* js_array_length = Smi::cast(cached_fixed_array_last_element);
+      result_array->set_length(js_array_length);
+      RegExpImpl::SetLastMatchInfo(last_match_array, subject, capture_count,
+                                   NULL);
+      return *result_array;
+    }
+  }
+
+  RegExpImpl::GlobalCache global_cache(regexp, subject, true, isolate);
+  if (global_cache.HasException()) return isolate->heap()->exception();
+
+  // Ensured in Runtime_RegExpExecMultiple.
+  DCHECK(result_array->HasFastObjectElements());
+  Handle<FixedArray> result_elements(
+      FixedArray::cast(result_array->elements()));
+  if (result_elements->length() < 16) {
+    result_elements = isolate->factory()->NewFixedArrayWithHoles(16);
+  }
+
+  FixedArrayBuilder builder(result_elements);
+
+  // Position to search from.
+  int match_start = -1;
+  int match_end = 0;
+  bool first = true;
+
+  // Two smis before and after the match, for very long strings.
+  static const int kMaxBuilderEntriesPerRegExpMatch = 5;
+
+  while (true) {
+    int32_t* current_match = global_cache.FetchNext();
+    if (current_match == NULL) break;
+    match_start = current_match[0];
+    builder.EnsureCapacity(kMaxBuilderEntriesPerRegExpMatch);
+    if (match_end < match_start) {
+      ReplacementStringBuilder::AddSubjectSlice(&builder, match_end,
+                                                match_start);
+    }
+    match_end = current_match[1];
+    {
+      // Avoid accumulating new handles inside loop.
+      HandleScope temp_scope(isolate);
+      Handle<String> match;
+      if (!first) {
+        match = isolate->factory()->NewProperSubString(subject, match_start,
+                                                       match_end);
+      } else {
+        match =
+            isolate->factory()->NewSubString(subject, match_start, match_end);
+        first = false;
+      }
+
+      if (has_capture) {
+        // Arguments array to replace function is match, captures, index and
+        // subject, i.e., 3 + capture count in total.
+        Handle<FixedArray> elements =
+            isolate->factory()->NewFixedArray(3 + capture_count);
+
+        elements->set(0, *match);
+        for (int i = 1; i <= capture_count; i++) {
+          int start = current_match[i * 2];
+          if (start >= 0) {
+            int end = current_match[i * 2 + 1];
+            DCHECK(start <= end);
+            Handle<String> substring =
+                isolate->factory()->NewSubString(subject, start, end);
+            elements->set(i, *substring);
+          } else {
+            DCHECK(current_match[i * 2 + 1] < 0);
+            elements->set(i, isolate->heap()->undefined_value());
+          }
+        }
+        elements->set(capture_count + 1, Smi::FromInt(match_start));
+        elements->set(capture_count + 2, *subject);
+        builder.Add(*isolate->factory()->NewJSArrayWithElements(elements));
+      } else {
+        builder.Add(*match);
+      }
+    }
+  }
+
+  if (global_cache.HasException()) return isolate->heap()->exception();
+
+  if (match_start >= 0) {
+    // Finished matching, with at least one match.
+    if (match_end < subject_length) {
+      ReplacementStringBuilder::AddSubjectSlice(&builder, match_end,
+                                                subject_length);
+    }
+
+    RegExpImpl::SetLastMatchInfo(last_match_array, subject, capture_count,
+                                 NULL);
+
+    if (subject_length > kMinLengthToCache) {
+      // Store the length of the result array into the last element of the
+      // backing FixedArray.
+      builder.EnsureCapacity(1);
+      Handle<FixedArray> fixed_array = builder.array();
+      fixed_array->set(fixed_array->length() - 1,
+                       Smi::FromInt(builder.length()));
+      // Cache the result and turn the FixedArray into a COW array.
+      RegExpResultsCache::Enter(isolate, subject,
+                                handle(regexp->data(), isolate), fixed_array,
+                                RegExpResultsCache::REGEXP_MULTIPLE_INDICES);
+    }
+    return *builder.ToJSArray(result_array);
+  } else {
+    return isolate->heap()->null_value();  // No matches at all.
+  }
+}
+
+
+// This is only called for StringReplaceGlobalRegExpWithFunction.  This sets
+// lastMatchInfoOverride to maintain the last match info, so we don't need to
+// set any other last match array info.
+RUNTIME_FUNCTION(Runtime_RegExpExecMultiple) {
+  HandleScope handles(isolate);
+  DCHECK(args.length() == 4);
+
+  CONVERT_ARG_HANDLE_CHECKED(String, subject, 1);
+  CONVERT_ARG_HANDLE_CHECKED(JSRegExp, regexp, 0);
+  CONVERT_ARG_HANDLE_CHECKED(JSArray, last_match_info, 2);
+  CONVERT_ARG_HANDLE_CHECKED(JSArray, result_array, 3);
+  RUNTIME_ASSERT(last_match_info->HasFastObjectElements());
+  RUNTIME_ASSERT(result_array->HasFastObjectElements());
+
+  subject = String::Flatten(subject);
+  RUNTIME_ASSERT(regexp->GetFlags().is_global());
+
+  if (regexp->CaptureCount() == 0) {
+    return SearchRegExpMultiple<false>(isolate, subject, regexp,
+                                       last_match_info, result_array);
+  } else {
+    return SearchRegExpMultiple<true>(isolate, subject, regexp, last_match_info,
+                                      result_array);
+  }
+}
+
+
+RUNTIME_FUNCTION(RuntimeReference_RegExpConstructResult) {
+  SealHandleScope shs(isolate);
+  return __RT_impl_Runtime_RegExpConstructResult(args, isolate);
+}
+
+
+RUNTIME_FUNCTION(RuntimeReference_RegExpExec) {
+  SealHandleScope shs(isolate);
+  return __RT_impl_Runtime_RegExpExecRT(args, isolate);
+}
+
+
+// Perform string match of pattern on subject, starting at start index.
+// Caller must ensure that 0 <= start_index <= sub->length(),
+// and should check that pat->length() + start_index <= sub->length().
+int Runtime::StringMatch(Isolate* isolate, Handle<String> sub,
+                         Handle<String> pat, int start_index) {
+  DCHECK(0 <= start_index);
+  DCHECK(start_index <= sub->length());
+
+  int pattern_length = pat->length();
+  if (pattern_length == 0) return start_index;
+
+  int subject_length = sub->length();
+  if (start_index + pattern_length > subject_length) return -1;
+
+  sub = String::Flatten(sub);
+  pat = String::Flatten(pat);
+
+  DisallowHeapAllocation no_gc;  // ensure vectors stay valid
+  // Extract flattened substrings of cons strings before getting encoding.
+  String::FlatContent seq_sub = sub->GetFlatContent();
+  String::FlatContent seq_pat = pat->GetFlatContent();
+
+  // dispatch on type of strings
+  if (seq_pat.IsOneByte()) {
+    Vector<const uint8_t> pat_vector = seq_pat.ToOneByteVector();
+    if (seq_sub.IsOneByte()) {
+      return SearchString(isolate, seq_sub.ToOneByteVector(), pat_vector,
+                          start_index);
+    }
+    return SearchString(isolate, seq_sub.ToUC16Vector(), pat_vector,
+                        start_index);
+  }
+  Vector<const uc16> pat_vector = seq_pat.ToUC16Vector();
+  if (seq_sub.IsOneByte()) {
+    return SearchString(isolate, seq_sub.ToOneByteVector(), pat_vector,
+                        start_index);
+  }
+  return SearchString(isolate, seq_sub.ToUC16Vector(), pat_vector, start_index);
+}
+}
+}  // namespace v8::internal