Remove HType::HeapNumber from mutable heap numbers.

src/hydrogen.cc

 // Copyright 2013 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 "hydrogen.h"
 
 #include <algorithm>
 
 #include "v8.h"
 #include "allocation-site-scopes.h"
@@ skipping 5428 matching lines @@
       }
     }
   }
 
   HObjectAccess access = info->access();
   if (access.representation().IsDouble()) {
     // Load the heap number.
     checked_object = Add<HLoadNamedField>(
         checked_object, static_cast<HValue*>(NULL),
         access.WithRepresentation(Representation::Tagged()));
-    checked_object->set_type(HType::HeapNumber());
     // Load the double value from it.
     access = HObjectAccess::ForHeapNumberValue();
   }
 
   SmallMapList* map_list = info->field_maps();
   if (map_list->length() == 0) {
     return New<HLoadNamedField>(checked_object, checked_object, access);
   }
 
   UniqueSet<Map>* maps = new(zone()) UniqueSet<Map>(map_list->length(), zone());
@@ skipping 18 matching lines @@
     HObjectAccess heap_number_access =
         field_access.WithRepresentation(Representation::Tagged());
     if (transition_to_field) {
       // The store requires a mutable HeapNumber to be allocated.
       NoObservableSideEffectsScope no_side_effects(this);
       HInstruction* heap_number_size = Add<HConstant>(HeapNumber::kSize);
 
       PretenureFlag pretenure_flag = !FLAG_allocation_site_pretenuring ?
           isolate()->heap()->GetPretenureMode() : NOT_TENURED;
 
+      // Mark mutable heap numbers as Tagged rather than HeapNumber, since
+      // unlike immutable heap numbers, the identity of mutable heap numbers
+      // matters.
       HInstruction* heap_number = Add<HAllocate>(heap_number_size,
-          HType::HeapNumber(),
+          HType::Tagged(),
           pretenure_flag,
           HEAP_NUMBER_TYPE);
       AddStoreMapConstant(heap_number, isolate()->factory()->heap_number_map());
       Add<HStoreNamedField>(heap_number, HObjectAccess::ForHeapNumberValue(),
                             value);
       instr = New<HStoreNamedField>(checked_object->ActualValue(),
                                     heap_number_access,
                                     heap_number);
     } else {
       // Already holds a HeapNumber; load the box and write its value field.
       HInstruction* heap_number = Add<HLoadNamedField>(
           checked_object, static_cast<HValue*>(NULL), heap_number_access);
-      heap_number->set_type(HType::HeapNumber());
       instr = New<HStoreNamedField>(heap_number,
                                     HObjectAccess::ForHeapNumberValue(),
                                     value, STORE_TO_INITIALIZED_ENTRY);
     }
   } else {
     if (!info->field_maps()->is_empty()) {
       ASSERT(field_access.representation().IsHeapObject());
       BuildCheckHeapObject(value);
       value = Add<HCheckMaps>(value, info->field_maps());
 
@@ skipping 6300 matching lines @@
   if (ShouldProduceTraceOutput()) {
     isolate()->GetHTracer()->TraceHydrogen(name(), graph_);
   }
 
 #ifdef DEBUG
   graph_->Verify(false);  // No full verify.
 #endif
 }
 
 } }  // namespace v8::internal