[GR-54787] Fix documentation of unstructured locking in BytecodeParser.

PullRequest: graal/18069

Author: rmosaner

compiler/src/jdk.graal.compiler/src/jdk/graal/compiler/java/BytecodeParser.java

@@ -3037,8 +3037,12 @@ protected void genMonitorExit(ValueNode x, ValueNode escapedValue, int bci, bool
      */
     protected int minLockDepthAtMonitorExit(boolean inEpilogue) {
         /**
-         * Synchronized methods: Enforce that the method synchronized object is not unlocked outside
-         * the synchronized epilogue. Such a pattern could still be structured locking:
+         * Synchronized methods: Enforce that the method synchronized object is not unlocked before
+         * the synchronized epilogue.
+         *
+         * The
+         * {@code javasoft.sqe.tests.vm.instr.monitorexit.monitorexit009.monitorexit00901m1.monitorexit00901m1}
+         * test implies that unlocking the method synchronized object can be structured locking:
          *
          * <pre>
          * synchronized void foo() {

substratevm/src/com.oracle.svm.hosted/src/com/oracle/svm/hosted/phases/SharedGraphBuilderPhase.java

@@ -653,6 +653,23 @@ protected void genReturn(ValueNode returnVal, JavaKind returnKind) {
 
         @Override
         protected int minLockDepthAtMonitorExit(boolean inEpilogue) {
+            /**
+             * The
+             * {@code javasoft.sqe.tests.vm.instr.monitorexit.monitorexit009.monitorexit00901m1.monitorexit00901m1}
+             * test implies that unlocking the method synchronized object can be structured locking:
+             *
+             * <pre>
+             * synchronized void foo() {
+             *   monitorexit this // valid unlock of method synchronize object
+             *   // do something
+             *   monitorenter this
+             *   return
+             * }
+             * </pre>
+             *
+             * To be JCK compliant, it is only required to always have at least one locked object
+             * before performing a monitorexit.
+             */
             return 1;
         }