8291736: find_method_handle_intrinsic leaks Method*

Reviewed-by: hseigel, iklam, dholmes

Author: coleenp

src/hotspot/share/classfile/systemDictionary.cpp

@@ -2036,47 +2036,46 @@ Method* SystemDictionary::find_method_handle_intrinsic(vmIntrinsicID iid,
                                                        Symbol* signature,
                                                        TRAPS) {
 
-  methodHandle empty;
   const int iid_as_int = vmIntrinsics::as_int(iid);
   assert(MethodHandles::is_signature_polymorphic(iid) &&
          MethodHandles::is_signature_polymorphic_intrinsic(iid) &&
          iid != vmIntrinsics::_invokeGeneric,
          "must be a known MH intrinsic iid=%d: %s", iid_as_int, vmIntrinsics::name_at(iid));
 
-  Method** met;
-  InvokeMethodKey key(signature, iid_as_int);
   {
     MutexLocker ml(THREAD, InvokeMethodTable_lock);
-    met = _invoke_method_intrinsic_table.get(key);
+    InvokeMethodKey key(signature, iid_as_int);
+    Method** met = _invoke_method_intrinsic_table.get(key);
     if (met != nullptr) {
       return *met;
     }
-  }
 
-  methodHandle m = Method::make_method_handle_intrinsic(iid, signature, CHECK_NULL);
-  if (!Arguments::is_interpreter_only() || iid == vmIntrinsics::_linkToNative) {
-      // Generate a compiled form of the MH intrinsic
-      // linkToNative doesn't have interpreter-specific implementation, so always has to go through compiled version.
-      AdapterHandlerLibrary::create_native_wrapper(m);
-      // Check if have the compiled code.
-      if (!m->has_compiled_code()) {
-        THROW_MSG_NULL(vmSymbols::java_lang_VirtualMachineError(),
-                       "Out of space in CodeCache for method handle intrinsic");
-      }
-  }
-  // Now grab the lock.  We might have to throw away the new method,
-  // if a racing thread has managed to install one at the same time.
-  {
-    MutexLocker ml(THREAD, InvokeMethodTable_lock);
-    signature->make_permanent(); // The signature is never unloaded.
-    bool created;
-    met = _invoke_method_intrinsic_table.put_if_absent(key, m(), &created);
-    Method* saved_method = *met;
-    assert(Arguments::is_interpreter_only() || (saved_method->has_compiled_code() &&
-         saved_method->code()->entry_point() == saved_method->from_compiled_entry()),
-         "MH intrinsic invariant");
-    return saved_method;
+    bool throw_error = false;
+    // This function could get an OOM but it is safe to call inside of a lock because
+    // throwing OutOfMemoryError doesn't call Java code.
+    methodHandle m = Method::make_method_handle_intrinsic(iid, signature, CHECK_NULL);
+    if (!Arguments::is_interpreter_only() || iid == vmIntrinsics::_linkToNative) {
+        // Generate a compiled form of the MH intrinsic
+        // linkToNative doesn't have interpreter-specific implementation, so always has to go through compiled version.
+        AdapterHandlerLibrary::create_native_wrapper(m);
+        // Check if have the compiled code.
+        throw_error = (!m->has_compiled_code());
+    }
+
+    if (!throw_error) {
+      signature->make_permanent(); // The signature is never unloaded.
+      bool created = _invoke_method_intrinsic_table.put(key, m());
+      assert(created, "must be since we still hold the lock");
+      assert(Arguments::is_interpreter_only() || (m->has_compiled_code() &&
+             m->code()->entry_point() == m->from_compiled_entry()),
+             "MH intrinsic invariant");
+      return m();
+    }
   }
+
+  // Throw error outside of the lock.
+  THROW_MSG_NULL(vmSymbols::java_lang_VirtualMachineError(),
+                 "Out of space in CodeCache for method handle intrinsic");
 }
 
 // Helper for unpacking the return value from linkMethod and linkCallSite.