src/hotspot/cpu/aarch64/c1_LIRAssembler_aarch64.cpp

@@ -1341,16 +1341,15 @@
       // Object is null; update MDO and exit
       Register mdo  = klass_RInfo;
       __ mov_metadata(mdo, md->constant_encoding());
       Address data_addr
         = __ form_address(rscratch2, mdo,
-                          md->byte_offset_of_slot(data, DataLayout::DataLayout::header_offset()),
-                          LogBytesPerWord);
-      int header_bits = DataLayout::flag_mask_to_header_mask(BitData::null_seen_byte_constant());
-      __ ldr(rscratch1, data_addr);
-      __ orr(rscratch1, rscratch1, header_bits);
-      __ str(rscratch1, data_addr);
+                          md->byte_offset_of_slot(data, DataLayout::flags_offset()),
+                          0);
+      __ ldrb(rscratch1, data_addr);
+      __ orr(rscratch1, rscratch1, BitData::null_seen_byte_constant());
+      __ strb(rscratch1, data_addr);
       __ b(*obj_is_null);
       __ bind(not_null);
     } else {
       __ cbz(obj, *obj_is_null);
     }

@@ -1419,11 +1418,11 @@
     __ bind(profile_cast_failure);
     __ mov_metadata(mdo, md->constant_encoding());
     Address counter_addr
       = __ form_address(rscratch2, mdo,
                         md->byte_offset_of_slot(data, CounterData::count_offset()),
-                        LogBytesPerWord);
+                        0);
     __ ldr(rscratch1, counter_addr);
     __ sub(rscratch1, rscratch1, DataLayout::counter_increment);
     __ str(rscratch1, counter_addr);
     __ b(*failure);
   }

@@ -1468,16 +1467,15 @@
       // Object is null; update MDO and exit
       Register mdo  = klass_RInfo;
       __ mov_metadata(mdo, md->constant_encoding());
       Address data_addr
         = __ form_address(rscratch2, mdo,
-                          md->byte_offset_of_slot(data, DataLayout::header_offset()),
+                          md->byte_offset_of_slot(data, DataLayout::flags_offset()),
                           LogBytesPerInt);
-      int header_bits = DataLayout::flag_mask_to_header_mask(BitData::null_seen_byte_constant());
-      __ ldrw(rscratch1, data_addr);
-      __ orrw(rscratch1, rscratch1, header_bits);
-      __ strw(rscratch1, data_addr);
+      __ ldrb(rscratch1, data_addr);
+      __ orr(rscratch1, rscratch1, BitData::null_seen_byte_constant());
+      __ strb(rscratch1, data_addr);
       __ b(done);
       __ bind(not_null);
     } else {
       __ cbz(value, done);
     }