Replace C++ bitfields with our own BitFields

Shave this yak from orbit, it's the only way to be sure.

BUG=chromium:427616
LOG=n
R=svenpanne@chromium.org

Review URL: https://codereview.chromium.org/700963002

Cr-Commit-Position: refs/heads/master@{#25148}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25148 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/ast.cc

@@ -61,9 +61,9 @@ bool Expression::IsUndefinedLiteral(Isolate* isolate) const {
 
 VariableProxy::VariableProxy(Zone* zone, Variable* var, int position)
     : Expression(zone, position),
-      is_this_(var->is_this()),
-      is_assigned_(false),
-      is_resolved_(false),
+      bit_field_(IsThisField::encode(var->is_this()) |
+                 IsAssignedField::encode(false) |
+                 IsResolvedField::encode(false)),
       variable_feedback_slot_(FeedbackVectorICSlot::Invalid()),
       raw_name_(var->raw_name()),
       interface_(var->interface()) {
@@ -74,9 +74,8 @@ VariableProxy::VariableProxy(Zone* zone, Variable* var, int position)
 VariableProxy::VariableProxy(Zone* zone, const AstRawString* name, bool is_this,
                              Interface* interface, int position)
     : Expression(zone, position),
-      is_this_(is_this),
-      is_assigned_(false),
-      is_resolved_(false),
+      bit_field_(IsThisField::encode(is_this) | IsAssignedField::encode(false) |
+                 IsResolvedField::encode(false)),
       variable_feedback_slot_(FeedbackVectorICSlot::Invalid()),
       raw_name_(name),
       interface_(interface) {}
@@ -99,17 +98,17 @@ void VariableProxy::BindTo(Variable* var) {
 Assignment::Assignment(Zone* zone, Token::Value op, Expression* target,
                        Expression* value, int pos)
     : Expression(zone, pos),
-      is_uninitialized_(false),
-      key_type_(ELEMENT),
-      store_mode_(STANDARD_STORE),
-      op_(op),
+      bit_field_(IsUninitializedField::encode(false) |
+                 KeyTypeField::encode(ELEMENT) |
+                 StoreModeField::encode(STANDARD_STORE) |
+                 TokenField::encode(op)),
       target_(target),
       value_(value),
       binary_operation_(NULL) {}
 
 
 Token::Value Assignment::binary_op() const {
-  switch (op_) {
+  switch (op()) {
     case Token::ASSIGN_BIT_OR: return Token::BIT_OR;
     case Token::ASSIGN_BIT_XOR: return Token::BIT_XOR;
     case Token::ASSIGN_BIT_AND: return Token::BIT_AND;

src/heap-snapshot-generator-inl.h

@@ -12,7 +12,7 @@ namespace internal {
 
 
 HeapEntry* HeapGraphEdge::from() const {
-  return &snapshot()->entries()[from_index_];
+  return &snapshot()->entries()[from_index()];
 }
 
 

src/heap-snapshot-generator.cc

@@ -18,8 +18,7 @@ namespace internal {
 
 
 HeapGraphEdge::HeapGraphEdge(Type type, const char* name, int from, int to)
-    : type_(type),
-      from_index_(from),
+    : bit_field_(TypeField::encode(type) | FromIndexField::encode(from)),
       to_index_(to),
       name_(name) {
   DCHECK(type == kContextVariable
@@ -31,8 +30,7 @@ HeapGraphEdge::HeapGraphEdge(Type type, const char* name, int from, int to)
 
 
 HeapGraphEdge::HeapGraphEdge(Type type, int index, int from, int to)
-    : type_(type),
-      from_index_(from),
+    : bit_field_(TypeField::encode(type) | FromIndexField::encode(from)),
       to_index_(to),
       index_(index) {
   DCHECK(type == kElement || type == kHidden);

src/heap-snapshot-generator.h

@@ -28,22 +28,18 @@ class HeapGraphEdge BASE_EMBEDDED {
     kWeak = v8::HeapGraphEdge::kWeak
   };
 
-  HeapGraphEdge() { }
   HeapGraphEdge(Type type, const char* name, int from, int to);
   HeapGraphEdge(Type type, int index, int from, int to);
   void ReplaceToIndexWithEntry(HeapSnapshot* snapshot);
 
-  Type type() const { return static_cast<Type>(type_); }
+  Type type() const { return TypeField::decode(bit_field_); }
   int index() const {
-    DCHECK(type_ == kElement || type_ == kHidden);
+    DCHECK(type() == kElement || type() == kHidden);
     return index_;
   }
   const char* name() const {
-    DCHECK(type_ == kContextVariable
-        || type_ == kProperty
-        || type_ == kInternal
-        || type_ == kShortcut
-        || type_ == kWeak);
+    DCHECK(type() == kContextVariable || type() == kProperty ||
+           type() == kInternal || type() == kShortcut || type() == kWeak);
     return name_;
   }
   INLINE(HeapEntry* from() const);
@@ -51,9 +47,11 @@ class HeapGraphEdge BASE_EMBEDDED {
 
  private:
   INLINE(HeapSnapshot* snapshot() const);
+  int from_index() const { return FromIndexField::decode(bit_field_); }
 
-  unsigned type_ : 3;
-  int from_index_ : 29;
+  class TypeField : public BitField<Type, 0, 3> {};
+  class FromIndexField : public BitField<int, 3, 29> {};
+  uint32_t bit_field_;
   union {
     // During entries population |to_index_| is used for storing the index,
     // afterwards it is replaced with a pointer to the entry.

src/profile-generator-inl.h

@@ -10,14 +10,11 @@
 namespace v8 {
 namespace internal {
 
-CodeEntry::CodeEntry(Logger::LogEventsAndTags tag,
-                     const char* name,
-                     const char* name_prefix,
-                     const char* resource_name,
-                     int line_number,
-                     int column_number)
-    : tag_(tag),
-      builtin_id_(Builtins::builtin_count),
+CodeEntry::CodeEntry(Logger::LogEventsAndTags tag, const char* name,
+                     const char* name_prefix, const char* resource_name,
+                     int line_number, int column_number)
+    : bit_field_(TagField::encode(tag) |
+                 BuiltinIdField::encode(Builtins::builtin_count)),
       name_prefix_(name_prefix),
       name_(name),
       resource_name_(resource_name),
@@ -26,7 +23,7 @@ CodeEntry::CodeEntry(Logger::LogEventsAndTags tag,
       shared_id_(0),
       script_id_(v8::UnboundScript::kNoScriptId),
       no_frame_ranges_(NULL),
-      bailout_reason_(kEmptyBailoutReason) { }
+      bailout_reason_(kEmptyBailoutReason) {}
 
 
 bool CodeEntry::is_js_function_tag(Logger::LogEventsAndTags tag) {

src/profile-generator.cc

@@ -143,7 +143,7 @@ CodeEntry::~CodeEntry() {
 
 
 uint32_t CodeEntry::GetCallUid() const {
-  uint32_t hash = ComputeIntegerHash(tag_, v8::internal::kZeroHashSeed);
+  uint32_t hash = ComputeIntegerHash(tag(), v8::internal::kZeroHashSeed);
   if (shared_id_ != 0) {
     hash ^= ComputeIntegerHash(static_cast<uint32_t>(shared_id_),
                                v8::internal::kZeroHashSeed);
@@ -164,20 +164,18 @@ uint32_t CodeEntry::GetCallUid() const {
 
 
 bool CodeEntry::IsSameAs(CodeEntry* entry) const {
-  return this == entry
-      || (tag_ == entry->tag_
-          && shared_id_ == entry->shared_id_
-          && (shared_id_ != 0
-              || (name_prefix_ == entry->name_prefix_
-                  && name_ == entry->name_
-                  && resource_name_ == entry->resource_name_
-                  && line_number_ == entry->line_number_)));
+  return this == entry ||
+         (tag() == entry->tag() && shared_id_ == entry->shared_id_ &&
+          (shared_id_ != 0 ||
+           (name_prefix_ == entry->name_prefix_ && name_ == entry->name_ &&
+            resource_name_ == entry->resource_name_ &&
+            line_number_ == entry->line_number_)));
 }
 
 
 void CodeEntry::SetBuiltinId(Builtins::Name id) {
-  tag_ = Logger::BUILTIN_TAG;
-  builtin_id_ = id;
+  bit_field_ = TagField::update(bit_field_, Logger::BUILTIN_TAG);
+  bit_field_ = BuiltinIdField::update(bit_field_, id);
 }
 
 

src/profile-generator.h

@@ -55,7 +55,7 @@ class CodeEntry {
                    int column_number = v8::CpuProfileNode::kNoColumnNumberInfo);
   ~CodeEntry();
 
-  bool is_js_function() const { return is_js_function_tag(tag_); }
+  bool is_js_function() const { return is_js_function_tag(tag()); }
   const char* name_prefix() const { return name_prefix_; }
   bool has_name_prefix() const { return name_prefix_[0] != '\0'; }
   const char* name() const { return name_; }
@@ -78,7 +78,9 @@ class CodeEntry {
   }
 
   void SetBuiltinId(Builtins::Name id);
-  Builtins::Name builtin_id() const { return builtin_id_; }
+  Builtins::Name builtin_id() const {
+    return BuiltinIdField::decode(bit_field_);
+  }
 
   uint32_t GetCallUid() const;
   bool IsSameAs(CodeEntry* entry) const;
@@ -88,8 +90,11 @@ class CodeEntry {
   static const char* const kEmptyBailoutReason;
 
  private:
-  Logger::LogEventsAndTags tag_ : 8;
-  Builtins::Name builtin_id_ : 8;
+  class TagField : public BitField<Logger::LogEventsAndTags, 0, 8> {};
+  class BuiltinIdField : public BitField<Builtins::Name, 8, 8> {};
+  Logger::LogEventsAndTags tag() const { return TagField::decode(bit_field_); }
+
+  uint32_t bit_field_;
   const char* name_prefix_;
   const char* name_;
   const char* resource_name_;

src/runtime/runtime-array.cc

@@ -104,19 +104,19 @@ class ArrayConcatVisitor {
         storage_(Handle<FixedArray>::cast(
             isolate->global_handles()->Create(*storage))),
         index_offset_(0u),
-        fast_elements_(fast_elements),
-        exceeds_array_limit_(false) {}
+        bit_field_(FastElementsField::encode(fast_elements) |
+                   ExceedsLimitField::encode(false)) {}
 
   ~ArrayConcatVisitor() { clear_storage(); }
 
   void visit(uint32_t i, Handle<Object> elm) {
     if (i > JSObject::kMaxElementCount - index_offset_) {
-      exceeds_array_limit_ = true;
+      set_exceeds_array_limit(true);
       return;
     }
     uint32_t index = index_offset_ + i;
 
-    if (fast_elements_) {
+    if (fast_elements()) {
       if (index < static_cast<uint32_t>(storage_->length())) {
         storage_->set(index, *elm);
         return;
@@ -128,7 +128,7 @@ class ArrayConcatVisitor {
       SetDictionaryMode();
       // Fall-through to dictionary mode.
     }
-    DCHECK(!fast_elements_);
+    DCHECK(!fast_elements());
     Handle<SeededNumberDictionary> dict(
         SeededNumberDictionary::cast(*storage_));
     Handle<SeededNumberDictionary> result =
@@ -149,21 +149,23 @@ class ArrayConcatVisitor {
     // If the initial length estimate was off (see special case in visit()),
     // but the array blowing the limit didn't contain elements beyond the
     // provided-for index range, go to dictionary mode now.
-    if (fast_elements_ &&
+    if (fast_elements() &&
         index_offset_ >
             static_cast<uint32_t>(FixedArrayBase::cast(*storage_)->length())) {
       SetDictionaryMode();
     }
   }
 
-  bool exceeds_array_limit() { return exceeds_array_limit_; }
+  bool exceeds_array_limit() const {
+    return ExceedsLimitField::decode(bit_field_);
+  }
 
   Handle<JSArray> ToArray() {
     Handle<JSArray> array = isolate_->factory()->NewJSArray(0);
     Handle<Object> length =
         isolate_->factory()->NewNumber(static_cast<double>(index_offset_));
     Handle<Map> map = JSObject::GetElementsTransitionMap(
-        array, fast_elements_ ? FAST_HOLEY_ELEMENTS : DICTIONARY_ELEMENTS);
+        array, fast_elements() ? FAST_HOLEY_ELEMENTS : DICTIONARY_ELEMENTS);
     array->set_map(*map);
     array->set_length(*length);
     array->set_elements(*storage_);
@@ -173,7 +175,7 @@ class ArrayConcatVisitor {
  private:
   // Convert storage to dictionary mode.
   void SetDictionaryMode() {
-    DCHECK(fast_elements_);
+    DCHECK(fast_elements());
     Handle<FixedArray> current_storage(*storage_);
     Handle<SeededNumberDictionary> slow_storage(
         SeededNumberDictionary::New(isolate_, current_storage->length()));
@@ -191,7 +193,7 @@ class ArrayConcatVisitor {
     }
     clear_storage();
     set_storage(*slow_storage);
-    fast_elements_ = false;
+    set_fast_elements(false);
   }
 
   inline void clear_storage() {
@@ -203,13 +205,23 @@ class ArrayConcatVisitor {
         Handle<FixedArray>::cast(isolate_->global_handles()->Create(storage));
   }
 
+  class FastElementsField : public BitField<bool, 0, 1> {};
+  class ExceedsLimitField : public BitField<bool, 1, 1> {};
+
+  bool fast_elements() const { return FastElementsField::decode(bit_field_); }
+  void set_fast_elements(bool fast) {
+    bit_field_ = FastElementsField::update(bit_field_, fast);
+  }
+  void set_exceeds_array_limit(bool exceeds) {
+    bit_field_ = ExceedsLimitField::update(bit_field_, exceeds);
+  }
+
   Isolate* isolate_;
   Handle<FixedArray> storage_;  // Always a global handle.
   // Index after last seen index. Always less than or equal to
   // JSObject::kMaxElementCount.
   uint32_t index_offset_;
-  bool fast_elements_ : 1;
-  bool exceeds_array_limit_ : 1;
+  uint32_t bit_field_;
 };
 
 

src/scanner.cc

@@ -245,6 +245,8 @@ bool Scanner::SkipWhiteSpace() {
 
   while (true) {
     while (true) {
+      // The unicode cache accepts unsigned inputs.
+      if (c0_ < 0) break;
       // Advance as long as character is a WhiteSpace or LineTerminator.
       // Remember if the latter is the case.
       if (unicode_cache_->IsLineTerminator(c0_)) {
@@ -365,7 +367,7 @@ Token::Value Scanner::SkipMultiLineComment() {
   while (c0_ >= 0) {
     uc32 ch = c0_;
     Advance();
-    if (unicode_cache_->IsLineTerminator(ch)) {
+    if (c0_ >= 0 && unicode_cache_->IsLineTerminator(ch)) {
       // Following ECMA-262, section 7.4, a comment containing
       // a newline will make the comment count as a line-terminator.
       has_multiline_comment_before_next_ = true;
@@ -625,14 +627,14 @@ void Scanner::Scan() {
         break;
 
       default:
-        if (unicode_cache_->IsIdentifierStart(c0_)) {
+        if (c0_ < 0) {
+          token = Token::EOS;
+        } else if (unicode_cache_->IsIdentifierStart(c0_)) {
           token = ScanIdentifierOrKeyword();
         } else if (IsDecimalDigit(c0_)) {
           token = ScanNumber(false);
         } else if (SkipWhiteSpace()) {
           token = Token::WHITESPACE;
-        } else if (c0_ < 0) {
-          token = Token::EOS;
         } else {
           token = Select(Token::ILLEGAL);
         }
@@ -674,7 +676,7 @@ bool Scanner::ScanEscape() {
   Advance();
 
   // Skip escaped newlines.
-  if (unicode_cache_->IsLineTerminator(c)) {
+  if (c0_ >= 0 && unicode_cache_->IsLineTerminator(c)) {
     // Allow CR+LF newlines in multiline string literals.
     if (IsCarriageReturn(c) && IsLineFeed(c0_)) Advance();
     // Allow LF+CR newlines in multiline string literals.
@@ -871,7 +873,8 @@ Token::Value Scanner::ScanNumber(bool seen_period) {
   // not be an identifier start or a decimal digit; see ECMA-262
   // section 7.8.3, page 17 (note that we read only one decimal digit
   // if the value is 0).
-  if (IsDecimalDigit(c0_) || unicode_cache_->IsIdentifierStart(c0_))
+  if (IsDecimalDigit(c0_) ||
+      (c0_ >= 0 && unicode_cache_->IsIdentifierStart(c0_)))
     return Token::ILLEGAL;
 
   literal.Complete();
@@ -1039,7 +1042,7 @@ Token::Value Scanner::ScanIdentifierOrKeyword() {
   AddLiteralChar(first_char);
 
   // Scan the rest of the identifier characters.
-  while (unicode_cache_->IsIdentifierPart(c0_)) {
+  while (c0_ >= 0 && unicode_cache_->IsIdentifierPart(c0_)) {
     if (c0_ != '\\') {
       uc32 next_char = c0_;
       Advance();
@@ -1067,7 +1070,7 @@ Token::Value Scanner::ScanIdentifierOrKeyword() {
 
 Token::Value Scanner::ScanIdentifierSuffix(LiteralScope* literal) {
   // Scan the rest of the identifier characters.
-  while (unicode_cache_->IsIdentifierPart(c0_)) {
+  while (c0_ >= 0 && unicode_cache_->IsIdentifierPart(c0_)) {
     if (c0_ == '\\') {
       uc32 c = ScanIdentifierUnicodeEscape();
       // Only allow legal identifier part characters.
@@ -1106,10 +1109,10 @@ bool Scanner::ScanRegExpPattern(bool seen_equal) {
   }
 
   while (c0_ != '/' || in_character_class) {
-    if (unicode_cache_->IsLineTerminator(c0_) || c0_ < 0) return false;
+    if (c0_ < 0 || unicode_cache_->IsLineTerminator(c0_)) return false;
     if (c0_ == '\\') {  // Escape sequence.
       AddLiteralCharAdvance();
-      if (unicode_cache_->IsLineTerminator(c0_) || c0_ < 0) return false;
+      if (c0_ < 0 || unicode_cache_->IsLineTerminator(c0_)) return false;
       AddLiteralCharAdvance();
       // If the escape allows more characters, i.e., \x??, \u????, or \c?,
       // only "safe" characters are allowed (letters, digits, underscore),
@@ -1156,7 +1159,7 @@ bool Scanner::ScanLiteralUnicodeEscape() {
 bool Scanner::ScanRegExpFlags() {
   // Scan regular expression flags.
   LiteralScope literal(this);
-  while (unicode_cache_->IsIdentifierPart(c0_)) {
+  while (c0_ >= 0 && unicode_cache_->IsIdentifierPart(c0_)) {
     if (c0_ != '\\') {
       AddLiteralCharAdvance();
     } else {

src/unicode-inl.h

@@ -13,7 +13,7 @@ namespace unibrow {
 
 template <class T, int s> bool Predicate<T, s>::get(uchar code_point) {
   CacheEntry entry = entries_[code_point & kMask];
-  if (entry.code_point_ == code_point) return entry.value_;
+  if (entry.code_point() == code_point) return entry.value();
   return CalculateValue(code_point);
 }
 

src/unicode.h

@@ -7,6 +7,7 @@
 
 #include <sys/types.h>
 #include "src/globals.h"
+#include "src/utils.h"
 /**
  * \file
  * Definitions and convenience functions for working with unicode.
@@ -28,16 +29,26 @@ class Predicate {
  public:
   inline Predicate() { }
   inline bool get(uchar c);
+
  private:
   friend class Test;
   bool CalculateValue(uchar c);
-  struct CacheEntry {
-    inline CacheEntry() : code_point_(0), value_(0) { }
+  class CacheEntry {
+   public:
+    inline CacheEntry()
+        : bit_field_(CodePointField::encode(0) | ValueField::encode(0)) {}
     inline CacheEntry(uchar code_point, bool value)
-      : code_point_(code_point),
-        value_(value) { }
-    uchar code_point_ : 21;
-    bool value_ : 1;
+        : bit_field_(CodePointField::encode(code_point) |
+                     ValueField::encode(value)) {}
+
+    uchar code_point() const { return CodePointField::decode(bit_field_); }
+    bool value() const { return ValueField::decode(bit_field_); }
+
+   private:
+    class CodePointField : public v8::internal::BitField<uchar, 0, 21> {};
+    class ValueField : public v8::internal::BitField<bool, 21, 1> {};
+
+    uint32_t bit_field_;
   };
   static const int kSize = size;
   static const int kMask = kSize - 1;

src/utils.h

@@ -230,6 +230,14 @@ class BitFieldBase {
 };
 
 
+template <class T, int shift, int size>
+class BitField8 : public BitFieldBase<T, shift, size, uint8_t> {};
+
+
+template <class T, int shift, int size>
+class BitField16 : public BitFieldBase<T, shift, size, uint16_t> {};
+
+
 template<class T, int shift, int size>
 class BitField : public BitFieldBase<T, shift, size, uint32_t> { };