src/hotspot/cpu/aarch64/c2_MacroAssembler_aarch64.cpp

@@ -240,36 +240,42 @@
          cmp(obj, t2);
          br(Assembler::EQ, monitor_found);
          cache_offset = cache_offset + OMCache::oop_to_oop_difference();
        }
  
-       // Look for the monitor in the table.
- 
-       // Get the hash code.
-       ubfx(t1_hash, t3, markWord::hash_shift, markWord::hash_bits);
- 
-       // Get the table and calculate the bucket's address
-       lea(t3, ExternalAddress(ObjectMonitorTable::current_table_address()));
-       ldr(t3, Address(t3));
-       ldr(t2, Address(t3, ObjectMonitorTable::table_capacity_mask_offset()));
-       ands(t1_hash, t1_hash, t2);
-       ldr(t3, Address(t3, ObjectMonitorTable::table_buckets_offset()));
- 
-       // Read the monitor from the bucket.
-       ldr(t1_monitor, Address(t3, t1_hash, Address::lsl(LogBytesPerWord)));
- 
-       // Check if the monitor in the bucket is special (empty, tombstone or removed).
-       cmp(t1_monitor, (unsigned char)ObjectMonitorTable::SpecialPointerValues::below_is_special);
-       br(Assembler::LO, slow_path);
- 
-       // Check if object matches.
-       ldr(t3, Address(t1_monitor, ObjectMonitor::object_offset()));
-       BarrierSetAssembler* bs_asm = BarrierSet::barrier_set()->barrier_set_assembler();
-       bs_asm->try_resolve_weak_handle_in_c2(this, t3, t2, slow_path);
-       cmp(t3, obj);
-       br(Assembler::NE, slow_path);
- 
+       if (UseCompactObjectHeaders) {
+         // TODO: The fast-path table lookup currently doesn't work with Lilliput's
+         // compact identity-hashcode implementation.
+         // See: https://bugs.openjdk.org/browse/JDK-8380981
+         b(slow_path);
+       } else {
+         // Look for the monitor in the table.
+ 
+         // Get the hash code.
+         ubfx(t1_hash, t3, markWord::hash_shift, markWord::hash_bits);
+ 
+         // Get the table and calculate the bucket's address
+         lea(t3, ExternalAddress(ObjectMonitorTable::current_table_address()));
+         ldr(t3, Address(t3));
+         ldr(t2, Address(t3, ObjectMonitorTable::table_capacity_mask_offset()));
+         ands(t1_hash, t1_hash, t2);
+         ldr(t3, Address(t3, ObjectMonitorTable::table_buckets_offset()));
+ 
+         // Read the monitor from the bucket.
+         ldr(t1_monitor, Address(t3, t1_hash, Address::lsl(LogBytesPerWord)));
+ 
+         // Check if the monitor in the bucket is special (empty, tombstone or removed).
+         cmp(t1_monitor, (unsigned char)ObjectMonitorTable::SpecialPointerValues::below_is_special);
+         br(Assembler::LO, slow_path);
+ 
+         // Check if object matches.
+         ldr(t3, Address(t1_monitor, ObjectMonitor::object_offset()));
+         BarrierSetAssembler* bs_asm = BarrierSet::barrier_set()->barrier_set_assembler();
+         bs_asm->try_resolve_weak_handle_in_c2(this, t3, t2, slow_path);
+         cmp(t3, obj);
+         br(Assembler::NE, slow_path);
+       }
        bind(monitor_found);
      }
  
      const Register t2_owner_addr = t2;
      const Register t3_owner = t3;