8333300: [JVMCI] add support for generational ZGC

src/hotspot/share/jvmci/jvmciRuntime.cpp

@@ -874,7 +874,7 @@ int JVMCIRuntime::release_and_clear_oop_handles() {
     for (int i = 0; i < _oop_handles.length(); i++) {
       oop* oop_ptr = _oop_handles.at(i);
       guarantee(oop_ptr != nullptr, "release_cleared_oop_handles left null entry in _oop_handles");
-      guarantee(*oop_ptr != nullptr, "unexpected cleared handle");
+      guarantee(NativeAccess<>::oop_load(oop_ptr) != nullptr, "unexpected cleared handle");
       // Satisfy OopHandles::release precondition that all
       // handles being released are null.
       NativeAccess<>::oop_store(oop_ptr, (oop) nullptr);
@@ -889,7 +889,7 @@ int JVMCIRuntime::release_and_clear_oop_handles() {
 }
 
 static bool is_referent_non_null(oop* handle) {
-  return handle != nullptr && *handle != nullptr;
+  return handle != nullptr && NativeAccess<>::oop_load(handle) != nullptr;
 }
 
 // Swaps the elements in `array` at index `a` and index `b`

src/hotspot/share/jvmci/jvmci_globals.cpp

@@ -223,7 +223,7 @@ bool JVMCIGlobals::enable_jvmci_product_mode(JVMFlagOrigin origin, bool use_graa
 }
 
 bool JVMCIGlobals::gc_supports_jvmci() {
-  return UseSerialGC || UseParallelGC || UseG1GC || UseZGC;
+  return UseSerialGC || UseParallelGC || UseG1GC || UseZGC || UseEpsilonGC;
 }
 
 void JVMCIGlobals::check_jvmci_supported_gc() {