Replace C++ bitfields with our own BitFields

src/runtime/runtime-array.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #include "src/arguments.h"
 #include "src/runtime/runtime-utils.h"
 
 namespace v8 {
@@ skipping 86 matching lines @@
  * length overflows 32-bit non-negative integer.
  */
 class ArrayConcatVisitor {
  public:
   ArrayConcatVisitor(Isolate* isolate, Handle<FixedArray> storage,
                      bool fast_elements)
       : isolate_(isolate),
         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;
       }
       // Our initial estimate of length was foiled, possibly by
       // getters on the arrays increasing the length of later arrays
       // during iteration.
       // This shouldn't happen in anything but pathological cases.
       SetDictionaryMode();
       // Fall-through to dictionary mode.
     }
-    DCHECK(!fast_elements_);
+    DCHECK(!fast_elements());
     Handle<SeededNumberDictionary> dict(
         SeededNumberDictionary::cast(*storage_));
     Handle<SeededNumberDictionary> result =
         SeededNumberDictionary::AtNumberPut(dict, index, elm);
     if (!result.is_identical_to(dict)) {
       // Dictionary needed to grow.
       clear_storage();
       set_storage(*result);
     }
   }
 
   void increase_index_offset(uint32_t delta) {
     if (JSObject::kMaxElementCount - index_offset_ < delta) {
       index_offset_ = JSObject::kMaxElementCount;
     } else {
       index_offset_ += delta;
     }
     // 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_);
     return array;
   }
 
  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()));
     uint32_t current_length = static_cast<uint32_t>(current_storage->length());
     for (uint32_t i = 0; i < current_length; i++) {
       HandleScope loop_scope(isolate_);
       Handle<Object> element(current_storage->get(i), isolate_);
       if (!element->IsTheHole()) {
         Handle<SeededNumberDictionary> new_storage =
             SeededNumberDictionary::AtNumberPut(slow_storage, i, element);
         if (!new_storage.is_identical_to(slow_storage)) {
           slow_storage = loop_scope.CloseAndEscape(new_storage);
         }
       }
     }
     clear_storage();
     set_storage(*slow_storage);
-    fast_elements_ = false;
+    set_fast_elements(false);
   }
 
   inline void clear_storage() {
     GlobalHandles::Destroy(Handle<Object>::cast(storage_).location());
   }
 
   inline void set_storage(FixedArray* storage) {
     storage_ =
         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_;
 };
 
 
 static uint32_t EstimateElementCount(Handle<JSArray> array) {
   uint32_t length = static_cast<uint32_t>(array->length()->Number());
   int element_count = 0;
   switch (array->GetElementsKind()) {
     case FAST_SMI_ELEMENTS:
     case FAST_HOLEY_SMI_ELEMENTS:
     case FAST_ELEMENTS:
@@ skipping 952 matching lines @@
 }
 
 
 RUNTIME_FUNCTION(RuntimeReference_FastOneByteArrayJoin) {
   SealHandleScope shs(isolate);
   DCHECK(args.length() == 2);
   return isolate->heap()->undefined_value();
 }
 }
 }  // namespace v8::internal