Introduce FieldIndex to unify and abstract property/field offset

src/arm64/stub-cache-arm64.cc

Index: src/arm64/stub-cache-arm64.cc
diff --git a/src/arm64/stub-cache-arm64.cc b/src/arm64/stub-cache-arm64.cc
index ae597b2a0198584d6f2d953499fcad29520daff1..b933f65f44a8d5deaefea0002032a95c8245268d 100644
--- a/src/arm64/stub-cache-arm64.cc
+++ b/src/arm64/stub-cache-arm64.cc
@@ -522,12 +522,7 @@ void StoreStubCompiler::GenerateStoreField(MacroAssembler* masm,
   // checks.
   ASSERT(object->IsJSGlobalProxy() || !object->IsAccessCheckNeeded());
 
-  int index = lookup->GetFieldIndex().field_index();
-
-  // Adjust for the number of properties stored in the object. Even in the
-  // face of a transition we can use the old map here because the size of the
-  // object and the number of in-object properties is not going to change.
-  index -= object->map()->inobject_properties();
+  FieldIndex index = lookup->GetFieldIndex();
 
   Representation representation = lookup->representation();
   ASSERT(!representation.IsNone());
@@ -558,14 +553,12 @@ void StoreStubCompiler::GenerateStoreField(MacroAssembler* masm,
     __ SmiUntagToDouble(temp_double, value_reg, kSpeculativeUntag);
 
     // Load the double storage.
-    if (index < 0) {
-      int offset = (index * kPointerSize) + object->map()->instance_size();
-      __ Ldr(scratch1, FieldMemOperand(receiver_reg, offset));
+    if (index.is_inobject()) {
+      __ Ldr(scratch1, FieldMemOperand(receiver_reg, index.offset()));
     } else {
-      int offset = (index * kPointerSize) + FixedArray::kHeaderSize;
       __ Ldr(scratch1,
              FieldMemOperand(receiver_reg, JSObject::kPropertiesOffset));
-      __ Ldr(scratch1, FieldMemOperand(scratch1, offset));
+      __ Ldr(scratch1, FieldMemOperand(scratch1, index.offset()));
     }
 
     // Store the value into the storage.
@@ -589,10 +582,9 @@ void StoreStubCompiler::GenerateStoreField(MacroAssembler* masm,
   // TODO(verwaest): Share this code as a code stub.
   SmiCheck smi_check = representation.IsTagged()
       ? INLINE_SMI_CHECK : OMIT_SMI_CHECK;
-  if (index < 0) {
+  if (index.is_inobject()) {
     // Set the property straight into the object.
-    int offset = object->map()->instance_size() + (index * kPointerSize);
-    __ Str(value_reg, FieldMemOperand(receiver_reg, offset));
+    __ Str(value_reg, FieldMemOperand(receiver_reg, index.offset()));
 
     if (!representation.IsSmi()) {
       // Skip updating write barrier if storing a smi.
@@ -602,7 +594,7 @@ void StoreStubCompiler::GenerateStoreField(MacroAssembler* masm,
       // Pass the now unused name_reg as a scratch register.
       __ Mov(name_reg, value_reg);
       __ RecordWriteField(receiver_reg,
-                          offset,
+                          index.offset(),
                           name_reg,
                           scratch1,
                           kLRHasNotBeenSaved,
@@ -612,11 +604,10 @@ void StoreStubCompiler::GenerateStoreField(MacroAssembler* masm,
     }
   } else {
     // Write to the properties array.
-    int offset = index * kPointerSize + FixedArray::kHeaderSize;
     // Get the properties array
     __ Ldr(scratch1,
            FieldMemOperand(receiver_reg, JSObject::kPropertiesOffset));
-    __ Str(value_reg, FieldMemOperand(scratch1, offset));
+    __ Str(value_reg, FieldMemOperand(scratch1, index.offset()));
 
     if (!representation.IsSmi()) {
       // Skip updating write barrier if storing a smi.
@@ -626,7 +617,7 @@ void StoreStubCompiler::GenerateStoreField(MacroAssembler* masm,
       // Ok to clobber receiver_reg and name_reg, since we return.
       __ Mov(name_reg, value_reg);
       __ RecordWriteField(scratch1,
-                          offset,
+                          index.offset(),
                           name_reg,
                           receiver_reg,
                           kLRHasNotBeenSaved,
@@ -967,20 +958,14 @@ Register LoadStubCompiler::CallbackHandlerFrontend(Handle<HeapType> type,
 
 void LoadStubCompiler::GenerateLoadField(Register reg,
                                          Handle<JSObject> holder,
-                                         PropertyIndex field,
+                                         FieldIndex field,
                                          Representation representation) {
   __ Mov(receiver(), reg);
   if (kind() == Code::LOAD_IC) {
-    LoadFieldStub stub(isolate(),
-                       field.is_inobject(holder),
-                       field.translate(holder),
-                       representation);
+    LoadFieldStub stub(isolate(), field);
     GenerateTailCall(masm(), stub.GetCode());
   } else {
-    KeyedLoadFieldStub stub(isolate(),
-                            field.is_inobject(holder),
-                            field.translate(holder),
-                            representation);
+    KeyedLoadFieldStub stub(isolate(), field);
     GenerateTailCall(masm(), stub.GetCode());
   }
 }