Add pointer cache field to external string for access in generated code.

src/objects.cc

 // Copyright 2011 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 936 matching lines @@
     String::WriteToFlat(this, smart_chars.start(), 0, this->length());
     ASSERT(memcmp(smart_chars.start(),
                   resource->data(),
                   resource->length() * sizeof(smart_chars[0])) == 0);
   }
 #endif  // DEBUG
   Heap* heap = GetHeap();
   int size = this->Size();  // Byte size of the original string.
   if (size < ExternalString::kSize) {
     // The string is too small to fit an external String in its place. This can
-    // only happen for zero length strings.
+    // only happen for strings with less than 3 characters.
     return false;
   }
   ASSERT(size >= ExternalString::kSize);
   bool is_ascii = this->IsAsciiRepresentation();
   bool is_symbol = this->IsSymbol();
   int length = this->length();
   int hash_field = this->hash_field();
 
   // Morph the object to an external string by adjusting the map and
   // reinitializing the fields.
@@ skipping 33 matching lines @@
     String::WriteToFlat(this, smart_chars.start(), 0, this->length());
     ASSERT(memcmp(smart_chars.start(),
                   resource->data(),
                   resource->length() * sizeof(smart_chars[0])) == 0);
   }
 #endif  // DEBUG
   Heap* heap = GetHeap();
   int size = this->Size();  // Byte size of the original string.
   if (size < ExternalString::kSize) {
     // The string is too small to fit an external String in its place. This can
-    // only happen for zero length strings.
+    // only happen for strings with less than 5 characters.
     return false;
   }
   ASSERT(size >= ExternalString::kSize);
   bool is_symbol = this->IsSymbol();
   int length = this->length();
   int hash_field = this->hash_field();
 
   // Morph the object to an external string by adjusting the map and
   // reinitializing the fields.
   this->set_map(heap->external_ascii_string_map());
@@ skipping 4761 matching lines @@
     string = slice->parent();
     shape = StringShape(string);
     ASSERT(shape.representation_tag() != kConsStringTag &&
            shape.representation_tag() != kSlicedStringTag);
   }
   if (shape.encoding_tag() == kAsciiStringTag) {
     const char* start;
     if (shape.representation_tag() == kSeqStringTag) {
       start = SeqAsciiString::cast(string)->GetChars();
     } else {
-      start = ExternalAsciiString::cast(string)->resource()->data();
+      start = ExternalAsciiString::cast(string)->GetChars();
     }
     return FlatContent(Vector<const char>(start + offset, length));
   } else {
     ASSERT(shape.encoding_tag() == kTwoByteStringTag);
     const uc16* start;
     if (shape.representation_tag() == kSeqStringTag) {
       start = SeqTwoByteString::cast(string)->GetChars();
     } else {
-      start = ExternalTwoByteString::cast(string)->resource()->data();
+      start = ExternalTwoByteString::cast(string)->GetChars();
     }
     return FlatContent(Vector<const uc16>(start + offset, length));
   }
 }
 
 
 SmartArrayPointer<char> String::ToCString(AllowNullsFlag allow_nulls,
                                           RobustnessFlag robust_flag,
                                           int offset,
                                           int length,
@@ skipping 214 matching lines @@
           max_chars > rbb->capacity ? rbb->capacity : max_chars);
       *offset_ptr = offset + offset_correction;
       return rbb->util_buffer;
     }
   }
 }
 
 
 uint16_t ExternalAsciiString::ExternalAsciiStringGet(int index) {
   ASSERT(index >= 0 && index < length());
-  return resource()->data()[index];
+  return GetChars()[index];
 }
 
 
 const unibrow::byte* ExternalAsciiString::ExternalAsciiStringReadBlock(
       unsigned* remaining,
       unsigned* offset_ptr,
       unsigned max_chars) {
   // Cast const char* to unibrow::byte* (signedness difference).
   const unibrow::byte* b =
-      reinterpret_cast<const unibrow::byte*>(resource()->data()) + *offset_ptr;
+      reinterpret_cast<const unibrow::byte*>(GetChars()) + *offset_ptr;
   *remaining = max_chars;
   *offset_ptr += max_chars;
   return b;
 }
 
 
 const uc16* ExternalTwoByteString::ExternalTwoByteStringGetData(
       unsigned start) {
-  return resource()->data() + start;
+  return GetChars() + start;

[Lasse Reichstein, 2011/11/17 13:40:18]

Functions like this are so small, it would be great if they could be inlined,
i.e., if they were in objects-inl.h instead.

 }
 
 
 uint16_t ExternalTwoByteString::ExternalTwoByteStringGet(int index) {
   ASSERT(index >= 0 && index < length());
-  return resource()->data()[index];
+  return GetChars()[index];
 }
 
 
 void ExternalTwoByteString::ExternalTwoByteStringReadBlockIntoBuffer(
       ReadBlockBuffer* rbb,
       unsigned* offset_ptr,
       unsigned max_chars) {
   unsigned chars_read = 0;
   unsigned offset = *offset_ptr;
-  const uint16_t* data = resource()->data();
+  const uint16_t* data = GetChars();
   while (chars_read < max_chars) {
     uint16_t c = data[offset];
     if (c <= kMaxAsciiCharCode) {
       // Fast case for ASCII characters. Cursor is an input output argument.
       if (!unibrow::CharacterStream::EncodeAsciiCharacter(c,
                                                           rbb->util_buffer,
                                                           rbb->capacity,
                                                           rbb->cursor))
         break;
     } else {
@@ skipping 25 matching lines @@
   rbb->cursor += max_chars;
 }
 
 
 void ExternalAsciiString::ExternalAsciiStringReadBlockIntoBuffer(
       ReadBlockBuffer* rbb,
       unsigned* offset_ptr,
       unsigned max_chars) {
   unsigned capacity = rbb->capacity - rbb->cursor;
   if (max_chars > capacity) max_chars = capacity;
-  memcpy(rbb->util_buffer + rbb->cursor,
-         resource()->data() + *offset_ptr,
-         max_chars);
+  memcpy(rbb->util_buffer + rbb->cursor, GetChars() + *offset_ptr, max_chars);
   rbb->remaining += max_chars;
   *offset_ptr += max_chars;
   rbb->cursor += max_chars;
 }
 
 
 // This method determines the type of string involved and then copies
 // a whole chunk of characters into a buffer, or returns a pointer to a buffer
 // where they can be found.  The pointer is not necessarily valid across a GC
 // (see AsciiStringReadBlock).
@@ skipping 421 matching lines @@
                          int f,
                          int t) {
   String* source = src;
   int from = f;
   int to = t;
   while (true) {
     ASSERT(0 <= from && from <= to && to <= source->length());
     switch (StringShape(source).full_representation_tag()) {
       case kAsciiStringTag | kExternalStringTag: {
         CopyChars(sink,
-                  ExternalAsciiString::cast(source)->resource()->data() + from,
+                  ExternalAsciiString::cast(source)->GetChars() + from,
                   to - from);
         return;
       }
       case kTwoByteStringTag | kExternalStringTag: {
         const uc16* data =
-            ExternalTwoByteString::cast(source)->resource()->data();
+            ExternalTwoByteString::cast(source)->GetChars();
         CopyChars(sink,
                   data + from,
                   to - from);
         return;
       }
       case kAsciiStringTag | kSeqStringTag: {
         CopyChars(sink,
                   SeqAsciiString::cast(source)->GetChars() + from,
                   to - from);
         return;
@@ skipping 5960 matching lines @@
   if (break_point_objects()->IsUndefined()) return 0;
   // Single break point.
   if (!break_point_objects()->IsFixedArray()) return 1;
   // Multiple break points.
   return FixedArray::cast(break_point_objects())->length();
 }
 #endif  // ENABLE_DEBUGGER_SUPPORT
 
 
 } }  // namespace v8::internal