Revert r14023 (Unify code for fast and slow path of JSON.stringify) from trunk.

src/runtime.cc

Index: src/runtime.cc
diff --git a/src/runtime.cc b/src/runtime.cc
index 38f77d07137eb06acec574d67d409cdfca073cd1..58f2a5153071eea0bd76ad383b77eae481e41778 100644
--- a/src/runtime.cc
+++ b/src/runtime.cc
@@ -5171,11 +5171,365 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_URIUnescape) {
 }
 
 
+static const unsigned int kQuoteTableLength = 128u;
+
+static const int kJsonQuotesCharactersPerEntry = 8;
+static const char* const JsonQuotes =
+    "\\u0000  \\u0001  \\u0002  \\u0003  "
+    "\\u0004  \\u0005  \\u0006  \\u0007  "
+    "\\b      \\t      \\n      \\u000b  "
+    "\\f      \\r      \\u000e  \\u000f  "
+    "\\u0010  \\u0011  \\u0012  \\u0013  "
+    "\\u0014  \\u0015  \\u0016  \\u0017  "
+    "\\u0018  \\u0019  \\u001a  \\u001b  "
+    "\\u001c  \\u001d  \\u001e  \\u001f  "
+    "        !       \\\"      #       "
+    "$       %       &       '       "
+    "(       )       *       +       "
+    ",       -       .       /       "
+    "0       1       2       3       "
+    "4       5       6       7       "
+    "8       9       :       ;       "
+    "<       =       >       ?       "
+    "@       A       B       C       "
+    "D       E       F       G       "
+    "H       I       J       K       "
+    "L       M       N       O       "
+    "P       Q       R       S       "
+    "T       U       V       W       "
+    "X       Y       Z       [       "
+    "\\\\      ]       ^       _       "
+    "`       a       b       c       "
+    "d       e       f       g       "
+    "h       i       j       k       "
+    "l       m       n       o       "
+    "p       q       r       s       "
+    "t       u       v       w       "
+    "x       y       z       {       "
+    "|       }       ~       \177       ";
+
+
+// For a string that is less than 32k characters it should always be
+// possible to allocate it in new space.
+static const int kMaxGuaranteedNewSpaceString = 32 * 1024;
+
+
+// Doing JSON quoting cannot make the string more than this many times larger.
+static const int kJsonQuoteWorstCaseBlowup = 6;
+
+static const int kSpaceForQuotesAndComma = 3;
+static const int kSpaceForBrackets = 2;
+
+// Covers the entire ASCII range (all other characters are unchanged by JSON
+// quoting).
+static const byte JsonQuoteLengths[kQuoteTableLength] = {
+    6, 6, 6, 6, 6, 6, 6, 6,
+    2, 2, 2, 6, 2, 2, 6, 6,
+    6, 6, 6, 6, 6, 6, 6, 6,
+    6, 6, 6, 6, 6, 6, 6, 6,
+    1, 1, 2, 1, 1, 1, 1, 1,
+    1, 1, 1, 1, 1, 1, 1, 1,
+    1, 1, 1, 1, 1, 1, 1, 1,
+    1, 1, 1, 1, 1, 1, 1, 1,
+    1, 1, 1, 1, 1, 1, 1, 1,
+    1, 1, 1, 1, 1, 1, 1, 1,
+    1, 1, 1, 1, 1, 1, 1, 1,
+    1, 1, 1, 1, 2, 1, 1, 1,
+    1, 1, 1, 1, 1, 1, 1, 1,
+    1, 1, 1, 1, 1, 1, 1, 1,
+    1, 1, 1, 1, 1, 1, 1, 1,
+    1, 1, 1, 1, 1, 1, 1, 1,
+};
+
+
+template <typename StringType>
+MaybeObject* AllocateRawString(Isolate* isolate, int length);
+
+
+template <>
+MaybeObject* AllocateRawString<SeqTwoByteString>(Isolate* isolate, int length) {
+  return isolate->heap()->AllocateRawTwoByteString(length);
+}
+
+
+template <>
+MaybeObject* AllocateRawString<SeqOneByteString>(Isolate* isolate, int length) {
+  return isolate->heap()->AllocateRawOneByteString(length);
+}
+
+
+template <typename Char, typename StringType, bool comma>
+static MaybeObject* SlowQuoteJsonString(Isolate* isolate,
+                                        Vector<const Char> characters) {
+  int length = characters.length();
+  const Char* read_cursor = characters.start();
+  const Char* end = read_cursor + length;
+  const int kSpaceForQuotes = 2 + (comma ? 1 :0);
+  int quoted_length = kSpaceForQuotes;
+  while (read_cursor < end) {
+    Char c = *(read_cursor++);
+    if (static_cast<unsigned>(c) >= kQuoteTableLength) {
+      quoted_length++;
+    } else {
+      quoted_length += JsonQuoteLengths[static_cast<unsigned>(c)];
+    }
+  }
+  MaybeObject* new_alloc = AllocateRawString<StringType>(isolate,
+                                                         quoted_length);
+  Object* new_object;
+  if (!new_alloc->ToObject(&new_object)) {
+    return new_alloc;
+  }
+  StringType* new_string = StringType::cast(new_object);
+
+  Char* write_cursor = reinterpret_cast<Char*>(
+      new_string->address() + SeqString::kHeaderSize);
+  if (comma) *(write_cursor++) = ',';
+  *(write_cursor++) = '"';
+
+  read_cursor = characters.start();
+  while (read_cursor < end) {
+    Char c = *(read_cursor++);
+    if (static_cast<unsigned>(c) >= kQuoteTableLength) {
+      *(write_cursor++) = c;
+    } else {
+      int len = JsonQuoteLengths[static_cast<unsigned>(c)];
+      const char* replacement = JsonQuotes +
+          static_cast<unsigned>(c) * kJsonQuotesCharactersPerEntry;
+      for (int i = 0; i < len; i++) {
+        *write_cursor++ = *replacement++;
+      }
+    }
+  }
+  *(write_cursor++) = '"';
+  return new_string;
+}
+
+
+template <typename SinkChar, typename SourceChar>
+static inline SinkChar* WriteQuoteJsonString(
+    Isolate* isolate,
+    SinkChar* write_cursor,
+    Vector<const SourceChar> characters) {
+  // SinkChar is only char if SourceChar is guaranteed to be char.
+  ASSERT(sizeof(SinkChar) >= sizeof(SourceChar));
+  const SourceChar* read_cursor = characters.start();
+  const SourceChar* end = read_cursor + characters.length();
+  *(write_cursor++) = '"';
+  while (read_cursor < end) {
+    SourceChar c = *(read_cursor++);
+    if (static_cast<unsigned>(c) >= kQuoteTableLength) {
+      *(write_cursor++) = static_cast<SinkChar>(c);
+    } else {
+      int len = JsonQuoteLengths[static_cast<unsigned>(c)];
+      const char* replacement = JsonQuotes +
+          static_cast<unsigned>(c) * kJsonQuotesCharactersPerEntry;
+      write_cursor[0] = replacement[0];
+      if (len > 1) {
+        write_cursor[1] = replacement[1];
+        if (len > 2) {
+          ASSERT(len == 6);
+          write_cursor[2] = replacement[2];
+          write_cursor[3] = replacement[3];
+          write_cursor[4] = replacement[4];
+          write_cursor[5] = replacement[5];
+        }
+      }
+      write_cursor += len;
+    }
+  }
+  *(write_cursor++) = '"';
+  return write_cursor;
+}
+
+
+template <typename Char, typename StringType, bool comma>
+static MaybeObject* QuoteJsonString(Isolate* isolate,
+                                    Vector<const Char> characters) {
+  int length = characters.length();
+  isolate->counters()->quote_json_char_count()->Increment(length);
+  int worst_case_length =
+        length * kJsonQuoteWorstCaseBlowup + kSpaceForQuotesAndComma;
+  if (worst_case_length > kMaxGuaranteedNewSpaceString) {
+    return SlowQuoteJsonString<Char, StringType, comma>(isolate, characters);
+  }
+
+  MaybeObject* new_alloc = AllocateRawString<StringType>(isolate,
+                                                         worst_case_length);
+  Object* new_object;
+  if (!new_alloc->ToObject(&new_object)) {
+    return new_alloc;
+  }
+  if (!isolate->heap()->new_space()->Contains(new_object)) {
+    // Even if our string is small enough to fit in new space we still have to
+    // handle it being allocated in old space as may happen in the third
+    // attempt.  See CALL_AND_RETRY in heap-inl.h and similar code in
+    // CEntryStub::GenerateCore.
+    return SlowQuoteJsonString<Char, StringType, comma>(isolate, characters);
+  }
+  StringType* new_string = StringType::cast(new_object);
+  ASSERT(isolate->heap()->new_space()->Contains(new_string));
+
+  Char* write_cursor = reinterpret_cast<Char*>(
+      new_string->address() + SeqString::kHeaderSize);
+  if (comma) *(write_cursor++) = ',';
+  write_cursor = WriteQuoteJsonString<Char, Char>(isolate,
+                                                  write_cursor,
+                                                  characters);
+  int final_length = static_cast<int>(
+      write_cursor - reinterpret_cast<Char*>(
+          new_string->address() + SeqString::kHeaderSize));
+  isolate->heap()->new_space()->
+      template ShrinkStringAtAllocationBoundary<StringType>(
+          new_string, final_length);
+  return new_string;
+}
+
+
 RUNTIME_FUNCTION(MaybeObject*, Runtime_QuoteJSONString) {
-  HandleScope scope(isolate);
-  CONVERT_ARG_HANDLE_CHECKED(String, string, 0);
+  NoHandleAllocation ha(isolate);
+  CONVERT_ARG_CHECKED(String, str, 0);
+  if (!str->IsFlat()) {
+    MaybeObject* try_flatten = str->TryFlatten();
+    Object* flat;
+    if (!try_flatten->ToObject(&flat)) {
+      return try_flatten;
+    }
+    str = String::cast(flat);
+    ASSERT(str->IsFlat());
+  }
+  String::FlatContent flat = str->GetFlatContent();
+  ASSERT(flat.IsFlat());
+  if (flat.IsTwoByte()) {
+    return QuoteJsonString<uc16, SeqTwoByteString, false>(isolate,
+                                                          flat.ToUC16Vector());
+  } else {
+    return QuoteJsonString<uint8_t, SeqOneByteString, false>(
+        isolate,
+        flat.ToOneByteVector());
+  }
+}
+
+
+RUNTIME_FUNCTION(MaybeObject*, Runtime_QuoteJSONStringComma) {
+  NoHandleAllocation ha(isolate);
+  CONVERT_ARG_CHECKED(String, str, 0);
+  if (!str->IsFlat()) {
+    MaybeObject* try_flatten = str->TryFlatten();
+    Object* flat;
+    if (!try_flatten->ToObject(&flat)) {
+      return try_flatten;
+    }
+    str = String::cast(flat);
+    ASSERT(str->IsFlat());
+  }
+  String::FlatContent flat = str->GetFlatContent();
+  if (flat.IsTwoByte()) {
+    return QuoteJsonString<uc16, SeqTwoByteString, true>(isolate,
+                                                         flat.ToUC16Vector());
+  } else {
+    return QuoteJsonString<uint8_t, SeqOneByteString, true>(
+        isolate,
+        flat.ToOneByteVector());
+  }
+}
+
+
+template <typename Char, typename StringType>
+static MaybeObject* QuoteJsonStringArray(Isolate* isolate,
+                                         FixedArray* array,
+                                         int worst_case_length) {
+  int length = array->length();
+
+  MaybeObject* new_alloc = AllocateRawString<StringType>(isolate,
+                                                         worst_case_length);
+  Object* new_object;
+  if (!new_alloc->ToObject(&new_object)) {
+    return new_alloc;
+  }
+  if (!isolate->heap()->new_space()->Contains(new_object)) {
+    // Even if our string is small enough to fit in new space we still have to
+    // handle it being allocated in old space as may happen in the third
+    // attempt.  See CALL_AND_RETRY in heap-inl.h and similar code in
+    // CEntryStub::GenerateCore.
+    return isolate->heap()->undefined_value();
+  }
+  AssertNoAllocation no_gc;
+  StringType* new_string = StringType::cast(new_object);
+  ASSERT(isolate->heap()->new_space()->Contains(new_string));
+
+  Char* write_cursor = reinterpret_cast<Char*>(
+      new_string->address() + SeqString::kHeaderSize);
+  *(write_cursor++) = '[';
+  for (int i = 0; i < length; i++) {
+    if (i != 0) *(write_cursor++) = ',';
+    String* str = String::cast(array->get(i));
+    String::FlatContent content = str->GetFlatContent();
+    ASSERT(content.IsFlat());
+    if (content.IsTwoByte()) {
+      write_cursor = WriteQuoteJsonString<Char, uc16>(isolate,
+                                                      write_cursor,
+                                                      content.ToUC16Vector());
+    } else {
+      write_cursor =
+          WriteQuoteJsonString<Char, uint8_t>(isolate,
+                                              write_cursor,
+                                              content.ToOneByteVector());
+    }
+  }
+  *(write_cursor++) = ']';
+
+  int final_length = static_cast<int>(
+      write_cursor - reinterpret_cast<Char*>(
+          new_string->address() + SeqString::kHeaderSize));
+  isolate->heap()->new_space()->
+      template ShrinkStringAtAllocationBoundary<StringType>(
+          new_string, final_length);
+  return new_string;
+}
+
+
+RUNTIME_FUNCTION(MaybeObject*, Runtime_QuoteJSONStringArray) {
+  NoHandleAllocation ha(isolate);
   ASSERT(args.length() == 1);
-  return BasicJsonStringifier::StringifyString(isolate, string);
+  CONVERT_ARG_CHECKED(JSArray, array, 0);
+
+  if (!array->HasFastObjectElements()) {
+    return isolate->heap()->undefined_value();
+  }
+  FixedArray* elements = FixedArray::cast(array->elements());
+  int n = elements->length();
+  bool ascii = true;
+  int total_length = 0;
+
+  for (int i = 0; i < n; i++) {
+    Object* elt = elements->get(i);
+    if (!elt->IsString()) return isolate->heap()->undefined_value();
+    String* element = String::cast(elt);
+    if (!element->IsFlat()) return isolate->heap()->undefined_value();
+    total_length += element->length();
+    if (ascii && element->IsTwoByteRepresentation()) {
+      ascii = false;
+    }
+  }
+
+  int worst_case_length =
+      kSpaceForBrackets + n * kSpaceForQuotesAndComma
+      + total_length * kJsonQuoteWorstCaseBlowup;
+
+  if (worst_case_length > kMaxGuaranteedNewSpaceString) {
+    return isolate->heap()->undefined_value();
+  }
+
+  if (ascii) {
+    return QuoteJsonStringArray<char, SeqOneByteString>(isolate,
+                                                      elements,
+                                                      worst_case_length);
+  } else {
+    return QuoteJsonStringArray<uc16, SeqTwoByteString>(isolate,
+                                                        elements,
+                                                        worst_case_length);
+  }
 }