src/cpu/x86/vm/templateTable_x86.cpp

rev 12163 : Replace read-barrier in monitor-search-loop with store checks.

@@ -4273,13 +4273,10 @@
   transition(atos, vtos);
 
   // check for NULL object
   __ null_check(rax);
 
-  // We need to preemptively evacuate the object, because we later compare
-  // it to objects in the BasicObjectLock list, and we might get false negatives
-  // if another thread evacuates the object in the meantime. See acmp.
   oopDesc::bs()->interpreter_write_barrier(_masm, rax);
 
   const Address monitor_block_top(
         rbp, frame::interpreter_frame_monitor_block_top_offset * wordSize);
   const Address monitor_block_bot(

@@ -4308,14 +4305,12 @@
     // check if current entry is used
     __ cmpptr(Address(rtop, BasicObjectLock::obj_offset_in_bytes()), (int32_t) NULL_WORD);
     // if not used then remember entry in rmon
     __ cmovptr(Assembler::equal, rmon, rtop);   // cmov => cmovptr
     // check if current entry is for same object
-    __ movptr(rscratch1, Address(rtop, BasicObjectLock::obj_offset_in_bytes()));
-    __ shenandoah_store_addr_check(rscratch1); // Invariant
-    oopDesc::bs()->interpreter_read_barrier(_masm, rscratch1);
-    __ cmpptr(rax, rscratch1);
+    __ shenandoah_lock_check(rtop); // Invariant
+    __ cmpptr(rax, Address(rtop, BasicObjectLock::obj_offset_in_bytes()));
     // if same object then stop searching
     __ jccb(Assembler::equal, exit);
     // otherwise advance to next entry
     __ addptr(rtop, entry_size);
     __ bind(entry);

@@ -4379,13 +4374,10 @@
   transition(atos, vtos);
 
   // check for NULL object
   __ null_check(rax);
 
-  // We need to preemptively evacuate the object, because we later compare
-  // it to objects in the BasicObjectLock list, and we might get false negatives
-  // if another thread evacuates the object in the meantime. See acmp.
   oopDesc::bs()->interpreter_write_barrier(_masm, rax);
 
   const Address monitor_block_top(
         rbp, frame::interpreter_frame_monitor_block_top_offset * wordSize);
   const Address monitor_block_bot(

@@ -4406,14 +4398,12 @@
                                         // of monitor block
     __ jmpb_if_possible(entry);
 
     __ bind(loop);
     // check if current entry is for same object
-    __ movptr(rscratch1, Address(rtop, BasicObjectLock::obj_offset_in_bytes()));
-    __ shenandoah_store_addr_check(rscratch1); // Invariant
-    oopDesc::bs()->interpreter_read_barrier(_masm, rscratch1);
-    __ cmpptr(rax, rscratch1);
+    __ shenandoah_lock_check(rtop); // Invariant
+    __ cmpptr(rax, Address(rtop, BasicObjectLock::obj_offset_in_bytes()));
     // if same object then stop searching
     __ jcc(Assembler::equal, found);
     // otherwise advance to next entry
     __ addptr(rtop, entry_size);
     __ bind(entry);