src/hotspot/share/gc/shenandoah/c2/shenandoahBarrierSetC2.cpp

@@ -223,12 +223,20 @@
            worklist.push(out);
            break;
          }
  
          case Op_LoadRange: {
-           // Array length is the same in all copies.
-           break;
+           // Array length is normally the same in all copies, so it can be read
+           // from a from-space copy without a barrier. With +UCOH, however, the
+           // array length lives in the mark word, which is overwritten by the
+           // forwarding pointer during evacuation, so reading it from a from-space
+           // copy would yield garbage. Keep the barrier in that case.
+           // Mirrors Op_LoadNKlass below.
+           if (!UseCompactObjectHeaders) {
+             break;
+           }
+           return false;
          }
  
          case Op_LoadKlass: {
            // Klass is the same in all copies.
            // We would have liked to assert -UCOH, but there are legitimate klass