[cleanup] Drop FLAG_eliminate_prototype_chain_checks

src/ic/x64/handler-compiler-x64.cc

Index: src/ic/x64/handler-compiler-x64.cc
diff --git a/src/ic/x64/handler-compiler-x64.cc b/src/ic/x64/handler-compiler-x64.cc
index 21d96eaabcfb9ba3ff696f42a31f455461a285d0..348f79cb21df0b22cd80e3d41c39da6fe8b4df85 100644
--- a/src/ic/x64/handler-compiler-x64.cc
+++ b/src/ic/x64/handler-compiler-x64.cc
@@ -440,29 +440,26 @@ Register PropertyHandlerCompiler::CheckPrototypes(
   DCHECK(!scratch2.is(object_reg) && !scratch2.is(holder_reg) &&
          !scratch2.is(scratch1));
 
-  if (FLAG_eliminate_prototype_chain_checks) {
-    Handle<Cell> validity_cell =
-        Map::GetOrCreatePrototypeChainValidityCell(receiver_map, isolate());
-    if (!validity_cell.is_null()) {
-      DCHECK_EQ(Smi::FromInt(Map::kPrototypeChainValid),
-                validity_cell->value());
-      __ Move(scratch1, validity_cell, RelocInfo::CELL);
-      // Move(..., CELL) loads the payload's address!
-      __ SmiCompare(Operand(scratch1, 0),
-                    Smi::FromInt(Map::kPrototypeChainValid));
-      __ j(not_equal, miss);
-    }
+  Handle<Cell> validity_cell =
+      Map::GetOrCreatePrototypeChainValidityCell(receiver_map, isolate());
+  if (!validity_cell.is_null()) {
+    DCHECK_EQ(Smi::FromInt(Map::kPrototypeChainValid), validity_cell->value());
+    __ Move(scratch1, validity_cell, RelocInfo::CELL);
+    // Move(..., CELL) loads the payload's address!
+    __ SmiCompare(Operand(scratch1, 0),
+                  Smi::FromInt(Map::kPrototypeChainValid));
+    __ j(not_equal, miss);
+  }
 
-    // The prototype chain of primitives (and their JSValue wrappers) depends
-    // on the native context, which can't be guarded by validity cells.
-    // |object_reg| holds the native context specific prototype in this case;
-    // we need to check its map.
-    if (check == CHECK_ALL_MAPS) {
-      __ movp(scratch1, FieldOperand(object_reg, HeapObject::kMapOffset));
-      Handle<WeakCell> cell = Map::WeakCellForMap(receiver_map);
-      __ CmpWeakValue(scratch1, cell, scratch2);
-      __ j(not_equal, miss);
-    }
+  // The prototype chain of primitives (and their JSValue wrappers) depends
+  // on the native context, which can't be guarded by validity cells.
+  // |object_reg| holds the native context specific prototype in this case;
+  // we need to check its map.
+  if (check == CHECK_ALL_MAPS) {
+    __ movp(scratch1, FieldOperand(object_reg, HeapObject::kMapOffset));
+    Handle<WeakCell> cell = Map::WeakCellForMap(receiver_map);
+    __ CmpWeakValue(scratch1, cell, scratch2);
+    __ j(not_equal, miss);
   }
 
   // Keep track of the current object in register reg.  On the first
@@ -500,8 +497,10 @@ Register PropertyHandlerCompiler::CheckPrototypes(
            !current_map->is_access_check_needed());
 
     prototype = handle(JSObject::cast(current_map->prototype()));
-    if (current_map->is_dictionary_map() &&
-        !current_map->IsJSGlobalObjectMap()) {
+    if (current_map->IsJSGlobalObjectMap()) {
+      GenerateCheckPropertyCell(masm(), Handle<JSGlobalObject>::cast(current),
+                                name, scratch2, miss);
+    } else if (current_map->is_dictionary_map()) {
       DCHECK(!current_map->IsJSGlobalProxyMap());  // Proxy maps are fast.
       if (!name->IsUniqueName()) {
         DCHECK(name->IsString());
@@ -511,34 +510,12 @@ Register PropertyHandlerCompiler::CheckPrototypes(
              current->property_dictionary()->FindEntry(name) ==
                  NameDictionary::kNotFound);
 
-      if (FLAG_eliminate_prototype_chain_checks && depth > 1) {
+      if (depth > 1) {
         // TODO(jkummerow): Cache and re-use weak cell.
         __ LoadWeakValue(reg, isolate()->factory()->NewWeakCell(current), miss);
       }
       GenerateDictionaryNegativeLookup(masm(), miss, reg, name, scratch1,
                                        scratch2);
-
-      if (!FLAG_eliminate_prototype_chain_checks) {
-        __ movp(scratch1, FieldOperand(reg, HeapObject::kMapOffset));
-        __ movp(holder_reg, FieldOperand(scratch1, Map::kPrototypeOffset));
-      }
-    } else {
-      Register map_reg = scratch1;
-      if (!FLAG_eliminate_prototype_chain_checks) {
-        __ movp(map_reg, FieldOperand(reg, HeapObject::kMapOffset));
-      }
-      if (current_map->IsJSGlobalObjectMap()) {
-        GenerateCheckPropertyCell(masm(), Handle<JSGlobalObject>::cast(current),
-                                  name, scratch2, miss);
-      } else if (!FLAG_eliminate_prototype_chain_checks &&
-                 (depth != 1 || check == CHECK_ALL_MAPS)) {
-        Handle<WeakCell> cell = Map::WeakCellForMap(current_map);
-        __ CmpWeakValue(map_reg, cell, scratch2);
-        __ j(not_equal, miss);
-      }
-      if (!FLAG_eliminate_prototype_chain_checks) {
-        __ movp(holder_reg, FieldOperand(map_reg, Map::kPrototypeOffset));
-      }
     }
 
     reg = holder_reg;  // From now on the object will be in holder_reg.
@@ -552,17 +529,8 @@ Register PropertyHandlerCompiler::CheckPrototypes(
   // Log the check depth.
   LOG(isolate(), IntEvent("check-maps-depth", depth + 1));
 
-  if (!FLAG_eliminate_prototype_chain_checks &&
-      (depth != 0 || check == CHECK_ALL_MAPS)) {
-    // Check the holder map.
-    __ movp(scratch1, FieldOperand(reg, HeapObject::kMapOffset));
-    Handle<WeakCell> cell = Map::WeakCellForMap(current_map);
-    __ CmpWeakValue(scratch1, cell, scratch2);
-    __ j(not_equal, miss);
-  }
-
   bool return_holder = return_what == RETURN_HOLDER;
-  if (FLAG_eliminate_prototype_chain_checks && return_holder && depth != 0) {
+  if (return_holder && depth != 0) {
     __ LoadWeakValue(reg, isolate()->factory()->NewWeakCell(current), miss);
   }