jvm: Fix Method internals detection on JVM 17

Author: oleavr

lib/jvm.js

@@ -806,23 +806,37 @@ function revertJvmMethod (method) {
 
 function _getJvmMethodSpec () {
   const api = getApi();
+  const { version } = api;
 
-  const adapterInConstMethod = (api.version > 8) ? 1 : 0;
+  let adapterHandlerLocation;
+  if (version >= 17) {
+    adapterHandlerLocation = 'method:early';
+  } else if (version >= 9 && version <= 16) {
+    adapterHandlerLocation = 'const-method';
+  } else {
+    adapterHandlerLocation = 'method:late';
+  }
 
   const isNative = 1;
   const methodSize = api['Method::size'](isNative) * pointerSize;
   const constMethodOffset = pointerSize;
   const methodDataOffset = 2 * pointerSize;
   const methodCountersOffset = 3 * pointerSize;
-  const accessFlagsOffset = 4 * pointerSize;
+  const adapterInMethodEarlyOffset = 4 * pointerSize;
+  const adapterInMethodEarlySize = (adapterHandlerLocation === 'method:early') ? pointerSize : 0;
+  const accessFlagsOffset = adapterInMethodEarlyOffset + adapterInMethodEarlySize;
   const vtableIndexOffset = accessFlagsOffset + 4;
-  const i2iEntryOffset = vtableIndexOffset + 4 + pointerSize;
+  const i2iEntryOffset = vtableIndexOffset + 4 + 8;
+  const adapterInMethodLateOffset = i2iEntryOffset + pointerSize;
+  const adapterInMethodOffset = (adapterInMethodEarlySize !== 0) ? adapterInMethodEarlyOffset : adapterInMethodLateOffset;
   const nativeFunctionOffset = methodSize - 2 * pointerSize;
   const signatureHandlerOffset = methodSize - pointerSize;
 
-  const constantPoolOffset = pointerSize;
-  const stackmapDataOffset = 2 * pointerSize;
-  const constMethodSizeOffset = (3 + adapterInConstMethod) * pointerSize;
+  const constantPoolOffset = 8;
+  const stackmapDataOffset = constantPoolOffset + pointerSize;
+  const adapterInConstMethodOffset = stackmapDataOffset + pointerSize;
+  const adapterInConstMethodSize = (adapterHandlerLocation === 'const-method') ? pointerSize : 0;
+  const constMethodSizeOffset = adapterInConstMethodOffset + adapterInConstMethodSize;
   const methodIdnumOffset = constMethodSizeOffset + 0xe;
 
   const cacheOffset = 2 * pointerSize;
@@ -833,12 +847,12 @@ function _getJvmMethodSpec () {
     klassSpec = getJvmKlassSpec(vtableOffset);
   }
 
-  const getAdapterPointer = adapterInConstMethod
+  const getAdapterPointer = (adapterInConstMethodSize !== 0)
     ? function (method, constMethod) {
-      return constMethod.add(constantPoolOffset + 2 * pointerSize);
+      return constMethod.add(adapterInConstMethodOffset);
     }
     : function (method, constMethod) {
-      return method.add(i2iEntryOffset + pointerSize);
+      return method.add(adapterInMethodOffset);
     };
 
   return {