When strings can change from an ASCII representation to a...

src/objects-inl.h

 // Copyright 2006-2008 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 126 matching lines @@
 
 bool Object::IsSeqString() {
   if (!IsString()) return false;
   return StringShape(String::cast(this)).IsSequential();
 }
 
 
 bool Object::IsSeqAsciiString() {
   if (!IsString()) return false;
   return StringShape(String::cast(this)).IsSequential() &&
-         StringShape(String::cast(this)).IsAsciiRepresentation();
+         String::cast(this)->IsAsciiRepresentation();
 }
 
 
 bool Object::IsSeqTwoByteString() {
   if (!IsString()) return false;
   return StringShape(String::cast(this)).IsSequential() &&
-         StringShape(String::cast(this)).IsTwoByteRepresentation();
+         String::cast(this)->IsTwoByteRepresentation();
 }
 
 
 bool Object::IsExternalString() {
   if (!IsString()) return false;
   return StringShape(String::cast(this)).IsExternal();
 }
 
 
 bool Object::IsExternalAsciiString() {
   if (!IsString()) return false;
   return StringShape(String::cast(this)).IsExternal() &&
-         StringShape(String::cast(this)).IsAsciiRepresentation();
+         String::cast(this)->IsAsciiRepresentation();
 }
 
 
 bool Object::IsExternalTwoByteString() {
   if (!IsString()) return false;
   return StringShape(String::cast(this)).IsExternal() &&
-         StringShape(String::cast(this)).IsTwoByteRepresentation();
+         String::cast(this)->IsTwoByteRepresentation();
 }
 
 
 bool Object::IsSlicedString() {
   if (!IsString()) return false;
   return StringShape(String::cast(this)).IsSliced();
 }
 
 
 #endif  // DEBUG
@@ skipping 19 matching lines @@
   ASSERT((type_ & kIsNotStringMask) == kStringTag);
 }
 
 
 bool StringShape::IsSymbol() {
   ASSERT(valid());
   return (type_ & kIsSymbolMask) == kSymbolTag;
 }
 
 
-bool StringShape::IsAsciiRepresentation() {
-  return (type_ & kStringEncodingMask) == kAsciiStringTag;
+bool String::IsAsciiRepresentation() {
+  uint32_t type = map()->instance_type();
+  if ((type & kStringRepresentationMask) == kSlicedStringTag) {
+    return SlicedString::cast(this)->buffer()->IsAsciiRepresentation();
+  } else if ((type & kStringRepresentationMask) == kConsStringTag &&

[Lasse Reichstein, 2009/05/01 09:47:01]

You can omit the "else" here, since the former condition always returns.

+             ConsString::cast(this)->second()->length() == 0) {
+    return ConsString::cast(this)->first()->IsAsciiRepresentation();
+  }
+  return (type & kStringEncodingMask) == kAsciiStringTag;
 }
 
 
-bool StringShape::IsTwoByteRepresentation() {
-  return (type_ & kStringEncodingMask) == kTwoByteStringTag;
+bool String::IsTwoByteRepresentation() {
+  uint32_t type = map()->instance_type();
+  if ((type & kStringRepresentationMask) == kSlicedStringTag) {
+    return SlicedString::cast(this)->buffer()->IsTwoByteRepresentation();
+  } else if ((type & kStringRepresentationMask) == kConsStringTag &&
+             ConsString::cast(this)->second()->length() == 0) {
+    return ConsString::cast(this)->first()->IsTwoByteRepresentation();
+  }
+  return (type & kStringEncodingMask) == kTwoByteStringTag;
 }
 
 
 bool StringShape::IsCons() {
   return (type_ & kStringRepresentationMask) == kConsStringTag;
 }
 
 
 bool StringShape::IsSliced() {
   return (type_ & kStringRepresentationMask) == kSlicedStringTag;
@@ skipping 1238 matching lines @@
 
   UNREACHABLE();
   return 0;
 }
 
 
 void String::Set(int index, uint16_t value) {
   ASSERT(index >= 0 && index < length());
   ASSERT(StringShape(this).IsSequential());
 
-  return StringShape(this).IsAsciiRepresentation()
+  return this->IsAsciiRepresentation()
       ? SeqAsciiString::cast(this)->SeqAsciiStringSet(index, value)
       : SeqTwoByteString::cast(this)->SeqTwoByteStringSet(index, value);
 }
 
 
 bool String::IsFlat() {
   switch (StringShape(this).representation_tag()) {
     case kConsStringTag: {
       String* second = ConsString::cast(this)->second();
       // Only flattened strings have second part empty.
@@ skipping 79 matching lines @@
 
   // Use the map (and not 'this') to compute the size tag, since
   // AsciiStringSize is called during GC when maps are encoded.
   length >>= StringShape(instance_type).size_tag() + kLongLengthShift;
 
   return SizeFor(length);
 }
 
 
 String* ConsString::first() {
-  ASSERT(String::cast(READ_FIELD(this, kSecondOffset))->length() != 0 ||
-      StringShape(
-          String::cast(
-              READ_FIELD(this, kFirstOffset))).IsAsciiRepresentation()
-          == StringShape(this).IsAsciiRepresentation());
   return String::cast(READ_FIELD(this, kFirstOffset));
 }
 
 
 Object* ConsString::unchecked_first() {
   return READ_FIELD(this, kFirstOffset);
 }
 
 
 void ConsString::set_first(String* value, WriteBarrierMode mode) {
@@ skipping 12 matching lines @@
 }
 
 
 void ConsString::set_second(String* value, WriteBarrierMode mode) {
   WRITE_FIELD(this, kSecondOffset, value);
   CONDITIONAL_WRITE_BARRIER(this, kSecondOffset, mode);
 }
 
 
 String* SlicedString::buffer() {
-  ASSERT(
-      StringShape(
-          String::cast(READ_FIELD(this, kBufferOffset))).IsAsciiRepresentation()
-      == StringShape(this).IsAsciiRepresentation());
   return String::cast(READ_FIELD(this, kBufferOffset));
 }
 
 
 void SlicedString::set_buffer(String* buffer) {
   WRITE_FIELD(this, kBufferOffset, buffer);
   WRITE_BARRIER(this, kBufferOffset);
 }
 
 
@@ skipping 970 matching lines @@
 #undef WRITE_INT_FIELD
 #undef READ_SHORT_FIELD
 #undef WRITE_SHORT_FIELD
 #undef READ_BYTE_FIELD
 #undef WRITE_BYTE_FIELD
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_INL_H_