8253434: Shenandoah: Cleanup ShenandoahRootScanner

Reviewed-by: rkennke

Author: zhengyu123

src/hotspot/share/gc/shenandoah/shenandoahConcurrentMark.cpp

@@ -107,20 +107,7 @@ class ShenandoahInitMarkRootsTask : public AbstractGangTask {
 
 private:
   void do_work(ShenandoahHeap* heap, OopClosure* oops, uint worker_id) {
-    // The rationale for selecting the roots to scan is as follows:
-    //   a. With unload_classes = true, we only want to scan the actual strong roots from the
-    //      code cache. This will allow us to identify the dead classes, unload them, *and*
-    //      invalidate the relevant code cache blobs. This could be only done together with
-    //      class unloading.
-    //   b. With unload_classes = false, we have to nominally retain all the references from code
-    //      cache, because there could be the case of embedded class/oop in the generated code,
-    //      which we will never visit during mark. Without code cache invalidation, as in (a),
-    //      we risk executing that code cache blob, and crashing.
-    if (heap->unload_classes()) {
-      _rp->strong_roots_do(worker_id, oops);
-    } else {
-      _rp->roots_do(worker_id, oops);
-    }
+    _rp->roots_do(worker_id, oops);
   }
 };
 

src/hotspot/share/gc/shenandoah/shenandoahRootProcessor.cpp

@@ -168,30 +168,13 @@ ShenandoahRootScanner::~ShenandoahRootScanner() {
 }
 
 void ShenandoahRootScanner::roots_do(uint worker_id, OopClosure* oops) {
-  CLDToOopClosure clds_cl(oops, ClassLoaderData::_claim_strong);
   MarkingCodeBlobClosure blobs_cl(oops, !CodeBlobToOopClosure::FixRelocations);
-  roots_do(worker_id, oops, &clds_cl, &blobs_cl);
+  roots_do(worker_id, oops, &blobs_cl);
 }
 
-void ShenandoahRootScanner::strong_roots_do(uint worker_id, OopClosure* oops) {
-  CLDToOopClosure clds_cl(oops, ClassLoaderData::_claim_strong);
-  MarkingCodeBlobClosure blobs_cl(oops, !CodeBlobToOopClosure::FixRelocations);
-  strong_roots_do(worker_id, oops, &clds_cl, &blobs_cl);
-}
-
-void ShenandoahRootScanner::roots_do(uint worker_id, OopClosure* oops, CLDClosure* clds, CodeBlobClosure* code, ThreadClosure *tc) {
-  assert(!ShenandoahSafepoint::is_at_shenandoah_safepoint() ||
-         !ShenandoahHeap::heap()->unload_classes(),
-          "Expect class unloading when Shenandoah cycle is running");
-  assert(clds != NULL, "Only possible with CLD closure");
-
-  ShenandoahParallelOopsDoThreadClosure tc_cl(oops, code, tc);
-  ResourceMark rm;
-  _thread_roots.threads_do(&tc_cl, worker_id);
-}
+void ShenandoahRootScanner::roots_do(uint worker_id, OopClosure* oops, CodeBlobClosure* code, ThreadClosure *tc) {
+  assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Must be at a safepoint");
 
-void ShenandoahRootScanner::strong_roots_do(uint worker_id, OopClosure* oops, CLDClosure* clds, CodeBlobClosure* code, ThreadClosure* tc) {
-  assert(ShenandoahHeap::heap()->unload_classes(), "Should be used during class unloading");
   ShenandoahParallelOopsDoThreadClosure tc_cl(oops, code, tc);
   ResourceMark rm;
   _thread_roots.threads_do(&tc_cl, worker_id);

src/hotspot/share/gc/shenandoah/shenandoahRootProcessor.hpp

@@ -197,15 +197,10 @@ class ShenandoahRootScanner : public ShenandoahRootProcessor {
   ShenandoahRootScanner(uint n_workers, ShenandoahPhaseTimings::Phase phase);
   ~ShenandoahRootScanner();
 
-  // Apply oops, clds and blobs to all strongly reachable roots in the system,
-  // during class unloading cycle
-  void strong_roots_do(uint worker_id, OopClosure* cl);
-  void strong_roots_do(uint worker_id, OopClosure* oops, CLDClosure* clds, CodeBlobClosure* code, ThreadClosure* tc = NULL);
-
-  // Apply oops, clds and blobs to all strongly reachable roots and weakly reachable
-  // roots when class unloading is disabled during this cycle
   void roots_do(uint worker_id, OopClosure* cl);
-  void roots_do(uint worker_id, OopClosure* oops, CLDClosure* clds, CodeBlobClosure* code, ThreadClosure* tc = NULL);
+
+private:
+  void roots_do(uint worker_id, OopClosure* oops, CodeBlobClosure* code, ThreadClosure* tc = NULL);
 };
 
 template <bool CONCURRENT>