6896624: G1: hotspot:::gc and hotspot:::mem-pool-gc probes are not fired

Summary: Fire the gc-begin and gc-end probes for G1.
Reviewed-by: kamg, ysr, jcoomes

src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp

@@ -1192,6 +1192,7 @@ bool G1CollectedHeap::do_collection(bool explicit_gc,
     return false;
   }
 
+  DTraceGCProbeMarker gc_probe_marker(true /* full */);
   ResourceMark rm;
 
   if (PrintHeapAtGC) {
@@ -3213,13 +3214,14 @@ G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
     return false;
   }
 
+  DTraceGCProbeMarker gc_probe_marker(false /* full */);
+  ResourceMark rm;
+
   if (PrintHeapAtGC) {
     Universe::print_heap_before_gc();
   }
 
   {
-    ResourceMark rm;
-
     // This call will decide whether this pause is an initial-mark
     // pause. If it is, during_initial_mark_pause() will return true
     // for the duration of this pause.

src/share/vm/gc_implementation/shared/vmGCOperations.hpp

@@ -209,4 +209,15 @@ class VM_GenCollectForPermanentAllocation: public VM_GC_Operation {
   HeapWord* result() const       { return _res; }
 };
 
+class DTraceGCProbeMarker : public StackObj {
+public:
+  DTraceGCProbeMarker(bool full) {
+    VM_GC_Operation::notify_gc_begin(full);
+  }
+
+  ~DTraceGCProbeMarker() {
+    VM_GC_Operation::notify_gc_end();
+  }
+};
+
 #endif // SHARE_VM_GC_IMPLEMENTATION_SHARED_VMGCOPERATIONS_HPP