8302462: [REDO] 8297487: G1 Remark: no need to keep alive oop constants of nmethods on stack

src/hotspot/share/gc/shared/barrierSet.cpp

@@ -57,11 +57,8 @@ static BarrierSetNMethod* select_barrier_set_nmethod(BarrierSetNMethod* barrier_
     // The GC needs nmethod entry barriers to do concurrent GC
     return barrier_set_nmethod;
   } else {
-    // The GC needs nmethod entry barriers for code cache unloading.
-    // Concurrent GC needs them also for preserving the weakly referenced objects in
-    // the constant pool of nmethods as part of the SATB snapshot, and to deal with
-    // compiled frames contained in continuation stack chunks allocated after
-    // concurent mark start.
+    // The GC needs nmethod entry barriers to deal with continuations
+    // and code cache unloading
     return new BarrierSetNMethod();
   }
 }

src/hotspot/share/gc/shared/barrierSetNMethod.cpp

@@ -99,6 +99,8 @@ bool BarrierSetNMethod::nmethod_entry_barrier(nmethod* nm) {
 
   // If the nmethod is the only thing pointing to the oops, and we are using a
   // SATB GC, then it is important that this code marks them live.
+  // Also, with concurrent GC, it is possible that frames in continuation stack
+  // chunks are not visited if they are allocated after concurrent GC started.
   OopKeepAliveClosure cl;
   nm->oops_do(&cl);