src/hotspot/cpu/x86/c2_MacroAssembler_x86.cpp

@@ -20,10 +20,11 @@
   * or visit www.oracle.com if you need additional information or have any
   * questions.
   *
   */
  
+ #include "../../share/runtime/globals.hpp"
  #include "asm/assembler.hpp"
  #include "asm/assembler.inline.hpp"
  #include "gc/shared/barrierSet.hpp"
  #include "gc/shared/barrierSetAssembler.hpp"
  #include "oops/methodData.hpp"

@@ -311,37 +312,43 @@
          cmpptr(obj, Address(thread, cache_offset));
          jccb(Assembler::equal, monitor_found);
          cache_offset = cache_offset + OMCache::oop_to_oop_difference();
        }
  
-       // Look for the monitor in the table.
- 
-       // Get the hash code.
-       movptr(hash, Address(obj, oopDesc::mark_offset_in_bytes()));
-       shrq(hash, markWord::hash_shift);
-       andq(hash, markWord::hash_mask);
- 
-       // Get the table and calculate the bucket's address.
-       lea(rax_reg, ExternalAddress(ObjectMonitorTable::current_table_address()));
-       movptr(rax_reg, Address(rax_reg));
-       andq(hash, Address(rax_reg, ObjectMonitorTable::table_capacity_mask_offset()));
-       movptr(rax_reg, Address(rax_reg, ObjectMonitorTable::table_buckets_offset()));
- 
-       // Read the monitor from the bucket.
-       movptr(monitor, Address(rax_reg, hash, Address::times_ptr));
- 
-       // Check if the monitor in the bucket is special (empty, tombstone or removed)
-       cmpptr(monitor, ObjectMonitorTable::SpecialPointerValues::below_is_special);
-       jcc(Assembler::below, slow_path);
- 
-       // Check if object matches.
-       movptr(rax_reg, Address(monitor, ObjectMonitor::object_offset()));
-       BarrierSetAssembler* bs_asm = BarrierSet::barrier_set()->barrier_set_assembler();
-       bs_asm->try_resolve_weak_handle_in_c2(this, rax_reg, slow_path);
-       cmpptr(rax_reg, obj);
-       jcc(Assembler::notEqual, 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
+         jmp(slow_path);
+       } else {
+         // Look for the monitor in the table.
+ 
+         // Get the hash code.
+         movptr(hash, Address(obj, oopDesc::mark_offset_in_bytes()));
+         shrq(hash, markWord::hash_shift);
+         andq(hash, markWord::hash_mask);
+ 
+         // Get the table and calculate the bucket's address.
+         lea(rax_reg, ExternalAddress(ObjectMonitorTable::current_table_address()));
+         movptr(rax_reg, Address(rax_reg));
+         andq(hash, Address(rax_reg, ObjectMonitorTable::table_capacity_mask_offset()));
+         movptr(rax_reg, Address(rax_reg, ObjectMonitorTable::table_buckets_offset()));
+ 
+         // Read the monitor from the bucket.
+         movptr(monitor, Address(rax_reg, hash, Address::times_ptr));
+ 
+         // Check if the monitor in the bucket is special (empty, tombstone or removed)
+         cmpptr(monitor, ObjectMonitorTable::SpecialPointerValues::below_is_special);
+         jcc(Assembler::below, slow_path);
+ 
+         // Check if object matches.
+         movptr(rax_reg, Address(monitor, ObjectMonitor::object_offset()));
+         BarrierSetAssembler* bs_asm = BarrierSet::barrier_set()->barrier_set_assembler();
+         bs_asm->try_resolve_weak_handle_in_c2(this, rax_reg, slow_path);
+         cmpptr(rax_reg, obj);
+         jcc(Assembler::notEqual, slow_path);
+       }
        bind(monitor_found);
      }
      const ByteSize monitor_tag = in_ByteSize(UseObjectMonitorTable ? 0 : checked_cast<int>(markWord::monitor_value));
      const Address recursions_address(monitor, ObjectMonitor::recursions_offset() - monitor_tag);
      const Address owner_address(monitor, ObjectMonitor::owner_offset() - monitor_tag);