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

@@ -59,10 +59,11 @@
  
  ShenandoahStackWatermark::ShenandoahStackWatermark(JavaThread* jt) :
    StackWatermark(jt, StackWatermarkKind::gc, _epoch_id),
    _heap(ShenandoahHeap::heap()),
    _stats(),
+   _no_op_cl(),
    _keep_alive_cl(),
    _evac_update_oop_cl(),
    _nm_cl() {}
  
  OopClosure* ShenandoahStackWatermark::closure_from_context(void* context) {

@@ -71,48 +72,48 @@
             _heap->is_concurrent_mark_in_progress(),
             "Only these two phases");
      assert(Thread::current()->is_Worker_thread(), "Unexpected thread passing in context: " PTR_FORMAT, p2i(context));
      return reinterpret_cast<OopClosure*>(context);
    } else {
-     if (_heap->is_concurrent_weak_root_in_progress()) {
-       assert(_heap->is_evacuation_in_progress(), "Nothing to evacuate");
+     if (_heap->is_concurrent_weak_root_in_progress() && _heap->is_evacuation_in_progress()) {
        return &_evac_update_oop_cl;
      } else if (_heap->is_concurrent_mark_in_progress()) {
        return &_keep_alive_cl;
+     } else if (ShenandoahGCStateCheckHotpatch) {
+       return &_no_op_cl;
      } else {
        ShouldNotReachHere();
        return nullptr;
      }
    }
  }
  
  void ShenandoahStackWatermark::start_processing_impl(void* context) {
    NoSafepointVerifier nsv;
-   ShenandoahHeap* const heap = ShenandoahHeap::heap();
  
-   // Process the non-frame part of the thread
-   if (heap->is_concurrent_weak_root_in_progress()) {
-     assert(heap->is_evacuation_in_progress(), "Should not be armed");
+   ShenandoahHeap* const heap = ShenandoahHeap::heap();
+   if (_heap->is_concurrent_weak_root_in_progress() && heap->is_evacuation_in_progress()) {
      // Retire the TLABs, which will force threads to reacquire their TLABs.
      // This is needed for two reasons. Strong one: new allocations would be with new freeset,
      // which would be outside the collection set, so no cset writes would happen there.
      // Weaker one: new allocations would happen past update watermark, and so less work would
      // be needed for reference updates (would update the large filler instead).
      retire_tlab();
- 
-     _jt->oops_do_no_frames(closure_from_context(context), &_nm_cl);
    } else if (heap->is_concurrent_mark_in_progress()) {
      // We need to reset all TLABs because they might be below the TAMS, and we need to mark
      // the objects in them. Do not let mutators allocate any new objects in their current TLABs.
      // It is also a good place to resize the TLAB sizes for future allocations.
      retire_tlab();
- 
-     _jt->oops_do_no_frames(closure_from_context(context), &_nm_cl);
+   } else if (ShenandoahGCStateCheckHotpatch) {
+     // Can be here for updating barriers. No TLAB retirement is needed.
    } else {
      ShouldNotReachHere();
    }
  
+   // Process the non-frame part of the thread
+   _jt->oops_do_no_frames(closure_from_context(context), &_nm_cl);
+ 
    // Publishes the processing start to concurrent threads
    StackWatermark::start_processing_impl(context);
  }
  
  void ShenandoahStackWatermark::retire_tlab() {

@@ -129,9 +130,9 @@
  void ShenandoahStackWatermark::process(const frame& fr, RegisterMap& register_map, void* context) {
    OopClosure* oops = closure_from_context(context);
    assert(oops != nullptr, "Should not get to here");
    ShenandoahHeap* const heap = ShenandoahHeap::heap();
    assert((heap->is_concurrent_weak_root_in_progress() && heap->is_evacuation_in_progress()) ||
-          heap->is_concurrent_mark_in_progress(),
-          "Only these two phases");
+          heap->is_concurrent_mark_in_progress() || ShenandoahGCStateCheckHotpatch,
+          "Only these phases");
    fr.oops_do(oops, &_nm_cl, &register_map, DerivedPointerIterationMode::_directly);
  }