Skip methods with JvmtiMountTransition annotation in findDecompileInfo

Java methods tagged with the JvmtiMountTransition annotation are
involved in transitioning between carrier to virtual threads, and
vice-versa. These methods are not part of the thread's scope. So,
they are skipped during introspection by the following JVMTI
functions:
- ForceEarlyReturn
- NotifyFramePop
- Local Variable (GetOrSetLocal)

This PR allows us to match the RI in jvmti/vthread/MethodExitTest.

Related #17490

Closes #17758

Co-authored-by: Gengchen Tuo <gengchen.tuo@ibm.com>
Signed-off-by: Babneet Singh <sbabneet@ca.ibm.com>

jcl/src/java.base/share/classes/jdk/internal/vm/Continuation.java

@@ -28,6 +28,7 @@
 import jdk.internal.access.JavaLangAccess;
 import jdk.internal.access.SharedSecrets;
 import jdk.internal.misc.Unsafe;
+import jdk.internal.vm.annotation.JvmtiMountTransition;
 
 /**
  * Continuation class performing the mount/unmount operation for VirtualThread
@@ -277,7 +278,9 @@ public PreemptStatus tryPreempt(Thread t) {
 	}
 
 	/* Continuation Native APIs */
+	@JvmtiMountTransition
 	private native boolean enterImpl();
-	private static native boolean yieldImpl(boolean isFinished);
 
+	@JvmtiMountTransition
+	private static native boolean yieldImpl(boolean isFinished);
 }

runtime/jvmti/jvmtiHelpers.c

@@ -1791,21 +1791,43 @@ static UDATA
 findDecompileInfoFrameIterator(J9VMThread *currentThread, J9StackWalkState *walkState)
 {
 	UDATA rc = J9_STACKWALK_KEEP_ITERATING;
+	J9Method *method = walkState->method;
+
+#if JAVA_SPEC_VERSION >= 20
+	J9ROMMethod *romMethod = NULL;
+	U_32 extendedModifiers = 0;
+
+	/* walkState->method can never be NULL since the J9_STACKWALK_VISIBLE_ONLY flag is set. */
+	Assert_JVMTI_true(NULL != method);
+
+	romMethod = J9_ROM_METHOD_FROM_RAM_METHOD(method);
+	extendedModifiers = getExtendedModifiersDataFromROMMethod(romMethod);
+
+	if (J9_ARE_ANY_BITS_SET(extendedModifiers, CFR_METHOD_EXT_JVMTIMOUNTTRANSITION_ANNOTATION)) {
+		goto skip;
+	}
+#endif /* JAVA_SPEC_VERSION >= 20 */
+
 	if (JVMTI_ERROR_NONE != (UDATA)walkState->userData1) {
 		/* The current frame is the requested frame.  Record the inline depth for the decompiler
 		 * and the method and bytecodePCOffset for the slot validator.
 		 */
 		walkState->userData1 = (void*)JVMTI_ERROR_NONE;
 		walkState->userData2 = (void*)walkState->inlineDepth;
-		walkState->userData3 = walkState->method;
+		walkState->userData3 = method;
 		walkState->userData4 = (void*)(UDATA)walkState->bytecodePCOffset;
 	}
+
 	/* Keep walking until the outer method is reached (the inline decompiler requires that
 	 * the walkState be at this point).
 	 */
 	if (0 == walkState->inlineDepth) {
 		rc = J9_STACKWALK_STOP_ITERATING;
 	}
+
+#if JAVA_SPEC_VERSION >= 20
+skip:
+#endif /* JAVA_SPEC_VERSION >= 20 */
 	return rc;
 }