src/hotspot/share/opto/library_call.cpp

@@ -3841,25 +3841,33 @@
    // The control of the load must be null. Otherwise, the load can move before
    // the null check after castPP removal.
    Node* no_ctrl = nullptr;
    Node* header = make_load(no_ctrl, header_addr, TypeX_X, TypeX_X->basic_type(), MemNode::unordered);
  
-   // Test the header to see if it is unlocked.
+   // Test the header to see if it is safe to read w.r.t. locking.
    Node *lock_mask      = _gvn.MakeConX(markWord::biased_lock_mask_in_place);
    Node *lmasked_header = _gvn.transform(new AndXNode(header, lock_mask));
-   Node *unlocked_val   = _gvn.MakeConX(markWord::unlocked_value);
-   Node *chk_unlocked   = _gvn.transform(new CmpXNode( lmasked_header, unlocked_val));
-   Node *test_unlocked  = _gvn.transform(new BoolNode( chk_unlocked, BoolTest::ne));
+   if (LockingMode == LM_LIGHTWEIGHT) {
+     Node *monitor_val   = _gvn.MakeConX(markWord::monitor_value);
+     Node *chk_monitor   = _gvn.transform(new CmpXNode(lmasked_header, monitor_val));
+     Node *test_monitor  = _gvn.transform(new BoolNode(chk_monitor, BoolTest::eq));
  
-   generate_slow_guard(test_unlocked, slow_region);
+     generate_slow_guard(test_monitor, slow_region);
+   } else {
+     Node *unlocked_val      = _gvn.MakeConX(markWord::unlocked_value);
+     Node *chk_unlocked      = _gvn.transform(new CmpXNode(lmasked_header, unlocked_val));
+     Node *test_not_unlocked = _gvn.transform(new BoolNode(chk_unlocked, BoolTest::ne));
+ 
+     generate_slow_guard(test_not_unlocked, slow_region);
+   }
  
    // Get the hash value and check to see that it has been properly assigned.
    // We depend on hash_mask being at most 32 bits and avoid the use of
    // hash_mask_in_place because it could be larger than 32 bits in a 64-bit
    // vm: see markWord.hpp.
-   Node *hash_mask      = _gvn.intcon(markWord::hash_mask);
-   Node *hash_shift     = _gvn.intcon(markWord::hash_shift);
+   Node *hash_mask      = _gvn.intcon(UseCompactObjectHeaders ? markWord::hash_mask_compact  : markWord::hash_mask);
+   Node *hash_shift     = _gvn.intcon(UseCompactObjectHeaders ? markWord::hash_shift_compact : markWord::hash_shift);
    Node *hshifted_header= _gvn.transform(new URShiftXNode(header, hash_shift));
    // This hack lets the hash bits live anywhere in the mark object now, as long
    // as the shift drops the relevant bits into the low 32 bits.  Note that
    // Java spec says that HashCode is an int so there's no point in capturing
    // an 'X'-sized hashcode (32 in 32-bit build or 64 in 64-bit build).