Derive string size constants

* The maximum length of short and medium sized strings is now derived from other constants.
* Remove the redundant String part of their names.
Review URL: http://codereview.chromium.org/347002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@3162 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/heap.cc

@@ -1810,10 +1810,10 @@ Object* Heap::AllocateConsString(String* first, String* second) {
   }
 
   Map* map;
-  if (length <= String::kMaxShortStringSize) {
+  if (length <= String::kMaxShortSize) {
     map = is_ascii ? short_cons_ascii_string_map()
       : short_cons_string_map();
-  } else if (length <= String::kMaxMediumStringSize) {
+  } else if (length <= String::kMaxMediumSize) {
     map = is_ascii ? medium_cons_ascii_string_map()
       : medium_cons_string_map();
   } else {
@@ -1843,11 +1843,11 @@ Object* Heap::AllocateSlicedString(String* buffer,
   }
 
   Map* map;
-  if (length <= String::kMaxShortStringSize) {
+  if (length <= String::kMaxShortSize) {
     map = buffer->IsAsciiRepresentation() ?
       short_sliced_ascii_string_map() :
       short_sliced_string_map();
-  } else if (length <= String::kMaxMediumStringSize) {
+  } else if (length <= String::kMaxMediumSize) {
     map = buffer->IsAsciiRepresentation() ?
       medium_sliced_ascii_string_map() :
       medium_sliced_string_map();
@@ -1912,9 +1912,9 @@ Object* Heap::AllocateExternalStringFromAscii(
     ExternalAsciiString::Resource* resource) {
   Map* map;
   int length = resource->length();
-  if (length <= String::kMaxShortStringSize) {
+  if (length <= String::kMaxShortSize) {
     map = short_external_ascii_string_map();
-  } else if (length <= String::kMaxMediumStringSize) {
+  } else if (length <= String::kMaxMediumSize) {
     map = medium_external_ascii_string_map();
   } else {
     map = long_external_ascii_string_map();
@@ -2659,18 +2659,18 @@ Object* Heap::AllocateInternalSymbol(unibrow::CharacterStream* buffer,
   Map* map;
 
   if (is_ascii) {
-    if (chars <= String::kMaxShortStringSize) {
+    if (chars <= String::kMaxShortSize) {
       map = short_ascii_symbol_map();
-    } else if (chars <= String::kMaxMediumStringSize) {
+    } else if (chars <= String::kMaxMediumSize) {
       map = medium_ascii_symbol_map();
     } else {
       map = long_ascii_symbol_map();
     }
     size = SeqAsciiString::SizeFor(chars);
   } else {
-    if (chars <= String::kMaxShortStringSize) {
+    if (chars <= String::kMaxShortSize) {
       map = short_symbol_map();
-    } else if (chars <= String::kMaxMediumStringSize) {
+    } else if (chars <= String::kMaxMediumSize) {
       map = medium_symbol_map();
     } else {
       map = long_symbol_map();
@@ -2720,9 +2720,9 @@ Object* Heap::AllocateRawAsciiString(int length, PretenureFlag pretenure) {
 
   // Determine the map based on the string's length.
   Map* map;
-  if (length <= String::kMaxShortStringSize) {
+  if (length <= String::kMaxShortSize) {
     map = short_ascii_string_map();
-  } else if (length <= String::kMaxMediumStringSize) {
+  } else if (length <= String::kMaxMediumSize) {
     map = medium_ascii_string_map();
   } else {
     map = long_ascii_string_map();
@@ -2757,9 +2757,9 @@ Object* Heap::AllocateRawTwoByteString(int length, PretenureFlag pretenure) {
 
   // Determine the map based on the string's length.
   Map* map;
-  if (length <= String::kMaxShortStringSize) {
+  if (length <= String::kMaxShortSize) {
     map = short_string_map();
-  } else if (length <= String::kMaxMediumStringSize) {
+  } else if (length <= String::kMaxMediumSize) {
     map = medium_string_map();
   } else {
     map = long_string_map();

src/objects-inl.h

@@ -1907,9 +1907,9 @@ void ExternalAsciiString::set_resource(
 Map* ExternalAsciiString::StringMap(int length) {
   Map* map;
   // Number of characters: determines the map.
-  if (length <= String::kMaxShortStringSize) {
+  if (length <= String::kMaxShortSize) {
     map = Heap::short_external_ascii_string_map();
-  } else if (length <= String::kMaxMediumStringSize) {
+  } else if (length <= String::kMaxMediumSize) {
     map = Heap::medium_external_ascii_string_map();
   } else {
     map = Heap::long_external_ascii_string_map();
@@ -1921,9 +1921,9 @@ Map* ExternalAsciiString::StringMap(int length) {
 Map* ExternalAsciiString::SymbolMap(int length) {
   Map* map;
   // Number of characters: determines the map.
-  if (length <= String::kMaxShortStringSize) {
+  if (length <= String::kMaxShortSize) {
     map = Heap::short_external_ascii_symbol_map();
-  } else if (length <= String::kMaxMediumStringSize) {
+  } else if (length <= String::kMaxMediumSize) {
     map = Heap::medium_external_ascii_symbol_map();
   } else {
     map = Heap::long_external_ascii_symbol_map();
@@ -1946,9 +1946,9 @@ void ExternalTwoByteString::set_resource(
 Map* ExternalTwoByteString::StringMap(int length) {
   Map* map;
   // Number of characters: determines the map.
-  if (length <= String::kMaxShortStringSize) {
+  if (length <= String::kMaxShortSize) {
     map = Heap::short_external_string_map();
-  } else if (length <= String::kMaxMediumStringSize) {
+  } else if (length <= String::kMaxMediumSize) {
     map = Heap::medium_external_string_map();
   } else {
     map = Heap::long_external_string_map();
@@ -1960,9 +1960,9 @@ Map* ExternalTwoByteString::StringMap(int length) {
 Map* ExternalTwoByteString::SymbolMap(int length) {
   Map* map;
   // Number of characters: determines the map.
-  if (length <= String::kMaxShortStringSize) {
+  if (length <= String::kMaxShortSize) {
     map = Heap::short_external_symbol_map();
-  } else if (length <= String::kMaxMediumStringSize) {
+  } else if (length <= String::kMaxMediumSize) {
     map = Heap::medium_external_symbol_map();
   } else {
     map = Heap::long_external_symbol_map();
@@ -2976,7 +2976,7 @@ StringHasher::StringHasher(int length)
 
 
 bool StringHasher::has_trivial_hash() {
-  return length_ > String::kMaxMediumStringSize;
+  return length_ > String::kMaxMediumSize;
 }
 
 

src/objects.cc

@@ -839,7 +839,7 @@ bool String::MakeExternal(v8::String::ExternalAsciiStringResource* resource) {
 
 void String::StringShortPrint(StringStream* accumulator) {
   int len = length();
-  if (len > kMaxMediumStringSize) {
+  if (len > kMaxMediumSize) {
     accumulator->Add("<Very long string[%u]>", len);
     return;
   }
@@ -4660,7 +4660,7 @@ static inline uint32_t HashField(uint32_t hash, bool is_array_index) {
 
 uint32_t StringHasher::GetHashField() {
   ASSERT(is_valid());
-  if (length_ <= String::kMaxShortStringSize) {
+  if (length_ <= String::kMaxShortSize) {
     uint32_t payload;
     if (is_array_index()) {
       payload = v8::internal::HashField(array_index(), true);
@@ -4669,7 +4669,7 @@ uint32_t StringHasher::GetHashField() {
     }
     return (payload & ((1 << String::kShortLengthShift) - 1)) |
            (length_ << String::kShortLengthShift);
-  } else if (length_ <= String::kMaxMediumStringSize) {
+  } else if (length_ <= String::kMaxMediumSize) {
     uint32_t payload = v8::internal::HashField(GetHash(), false);
     return (payload & ((1 << String::kMediumLengthShift) - 1)) |
            (length_ << String::kMediumLengthShift);

src/objects.h

@@ -4070,10 +4070,8 @@ class String: public HeapObject {
   static const int kSize = kLengthOffset + kIntSize;
   // Notice: kSize is not pointer-size aligned if pointers are 64-bit.
 
-  // Limits on sizes of different types of strings.
-  static const int kMaxShortStringSize = 63;
-  static const int kMaxMediumStringSize = 16383;
-
+  // Maximum number of characters to consider when trying to convert a string
+  // value into an array index.
   static const int kMaxArrayIndexSize = 10;
 
   // Max ascii char code.
@@ -4097,13 +4095,17 @@ class String: public HeapObject {
   // field.
   static const int kMaxCachedArrayIndexLength = 7;
 
-  // Shift constants for retriving length and hash code from
+  // Shift constants for retrieving length and hash code from
   // length/hash field.
   static const int kHashShift = kNofLengthBitFields;
   static const int kShortLengthShift = kHashShift + kShortStringTag;
   static const int kMediumLengthShift = kHashShift + kMediumStringTag;
   static const int kLongLengthShift = kHashShift + kLongStringTag;
-  // Maximal string length that can be stored in the hash/length field.
+
+  // Maximal string length that can be stored in the hash/length field for
+  // different types of strings.
+  static const int kMaxShortSize = (1 << (32 - kShortLengthShift)) - 1;
+  static const int kMaxMediumSize = (1 << (32 - kMediumLengthShift)) - 1;
   static const int kMaxLength = (1 << (32 - kLongLengthShift)) - 1;
 
   // Limit for truncation in short printing.

src/string-stream.cc

@@ -188,7 +188,7 @@ void StringStream::Add(Vector<const char> format, Vector<FmtElm> elms) {
 void StringStream::PrintObject(Object* o) {
   o->ShortPrint(this);
   if (o->IsString()) {
-    if (String::cast(o)->length() <= String::kMaxMediumStringSize) {
+    if (String::cast(o)->length() <= String::kMaxMediumSize) {
       return;
     }
   } else if (o->IsNumber() || o->IsOddball()) {

test/cctest/test-api.cc

@@ -6958,7 +6958,7 @@ static void MorphAString(i::String* string,
     CHECK(string->map() == i::Heap::short_external_ascii_string_map() ||
           string->map() == i::Heap::medium_external_ascii_string_map());
     // Morph external string to be TwoByte string.
-    if (string->length() <= i::String::kMaxShortStringSize) {
+    if (string->length() <= i::String::kMaxShortSize) {
       string->set_map(i::Heap::short_external_string_map());
     } else {
       string->set_map(i::Heap::medium_external_string_map());
@@ -6971,7 +6971,7 @@ static void MorphAString(i::String* string,
     CHECK(string->map() == i::Heap::short_external_string_map() ||
           string->map() == i::Heap::medium_external_string_map());
     // Morph external string to be ASCII string.
-    if (string->length() <= i::String::kMaxShortStringSize) {
+    if (string->length() <= i::String::kMaxShortSize) {
       string->set_map(i::Heap::short_external_ascii_string_map());
     } else {
       string->set_map(i::Heap::medium_external_ascii_string_map());