Short-circuit derived pointer processing

Author: pron

src/hotspot/share/compiler/oopMap.cpp

@@ -91,6 +91,7 @@ OopMap::OopMap(int frame_size, int arg_count) {
   set_write_stream(new CompressedWriteStream(32));
   set_omv_count(0);
   _num_oops = 0;
+  _has_derived_oops = false;
   _index = -1;
 
 #ifdef ASSERT
@@ -108,6 +109,7 @@ OopMap::OopMap(OopMap::DeepCopyToken, OopMap* source) {
   set_omv_count(0);
   set_offset(source->offset());
   _num_oops = source->num_oops();
+  _has_derived_oops = source->has_derived_oops();
   _index = -1;
 
 #ifdef ASSERT
@@ -315,8 +317,11 @@ void OopMap::set_xxx(VMReg reg, OopMapValue::oop_types x, VMReg optional) {
   OopMapValue o(reg, x, optional);
   o.write_on(write_stream());
   increment_count();
-  if (x == OopMapValue::oop_value || x == OopMapValue::narrowoop_value)
+  if (x == OopMapValue::oop_value || x == OopMapValue::narrowoop_value) {
     increment_num_oops();
+  } else if (x == OopMapValue::derived_oop_value) {
+    set_has_derived_oops(true);
+  }
 }
 
 
@@ -756,6 +761,7 @@ ImmutableOopMap::ImmutableOopMap(const OopMap* oopmap)
     _thaw_stub(NULL /*Continuations::default_thaw_oops_stub()*/), 
     _count(oopmap->count()), _num_oops(oopmap->num_oops()) {
   _num_oops = oopmap->num_oops();
+  _has_derived_oops = oopmap->has_derived_oops();
   address addr = data_addr();
   //oopmap->copy_data_to(addr);
   oopmap->copy_and_sort_data_to(addr);

src/hotspot/share/compiler/oopMap.hpp

@@ -157,6 +157,7 @@ class OopMap: public ResourceObj {
   int  _omv_count; // number of OopMapValues in the stream
   int  _num_oops;  // number of oops
   int  _index;     // index in OopMapSet
+  bool _has_derived_oops;
   CompressedWriteStream* _write_stream;
 
   debug_only( OopMapValue::oop_types* _locs_used; int _locs_length;)
@@ -166,6 +167,7 @@ class OopMap: public ResourceObj {
   void set_omv_count(int value)               { _omv_count = value; }
   void increment_count()                      { _omv_count++; }
   void increment_num_oops()                   { _num_oops++; }
+  void set_has_derived_oops(bool value)       { _has_derived_oops = value; }
   CompressedWriteStream* write_stream() const { return _write_stream; }
   void set_write_stream(CompressedWriteStream* value) { _write_stream = value; }
 
@@ -185,6 +187,7 @@ class OopMap: public ResourceObj {
   int data_size() const  { return write_stream()->position(); }
   address data() const { return write_stream()->buffer(); }
   int num_oops() const { return _num_oops; }
+  bool has_derived_oops() const { return _has_derived_oops; }
   int index() const { return _index; }
 
   // Construction
@@ -283,13 +286,15 @@ class ImmutableOopMap {
   mutable address _thaw_stub;
   int _count; // contains the number of entries in this OopMap
   int _num_oops;
+  bool _has_derived_oops;
 
   address data_addr() const { return (address) this + sizeof(ImmutableOopMap); }
 public:
   ImmutableOopMap(const OopMap* oopmap);
 
   int count() const { return _count; }
   int num_oops() const { return _num_oops; }
+  bool has_derived_oops() const { return _has_derived_oops; }
   bool has_any(OopMapValue::oop_types type) const;
 
 #ifdef ASSERT

src/hotspot/share/oops/instanceStackChunkKlass.cpp

@@ -320,17 +320,23 @@ void InstanceStackChunkKlass::fix_frame(const StackChunkFrameStream<mixed>& f, c
 
   run_nmethod_entry_barrier_if_needed<mixed>(f);
 
-  if (UseZGC || UseShenandoahGC) {
-    RelativizeDerivedPointers<true> derived_closure;
-    f.iterate_derived_pointers(&derived_closure, map);
+  assert (!f.is_compiled() || f.oopmap()->has_derived_oops() == f.oopmap()->has_any(OopMapValue::derived_oop_value), "");
+  bool has_derived = f.is_compiled() && f.oopmap()->has_derived_oops();
+  if (has_derived) {
+    if (UseZGC || UseShenandoahGC) {
+      RelativizeDerivedPointers<true> derived_closure;
+      f.iterate_derived_pointers(&derived_closure, map);
+    }
   }
 
   BarrierClosure<store> oops_closure(f.sp());
   f.iterate_oops(&oops_closure, map);
   OrderAccess::loadload(); // observing the barriers will prevent derived pointers from being derelativized concurrently
 
-  DerelativizeDerivedPointers derived_closure;
-  f.iterate_derived_pointers(&derived_closure, map);
+  if (has_derived) {
+    DerelativizeDerivedPointers derived_closure;
+    f.iterate_derived_pointers(&derived_closure, map);
+  }
 }
 
 template void InstanceStackChunkKlass::fix_frame<true,  false>(const StackChunkFrameStream<true >& f, const RegisterMap* map);

src/hotspot/share/oops/instanceStackChunkKlass.inline.hpp

@@ -934,12 +934,15 @@ class OopOopIterateStackClosure {
     }
 
     if (_do_destructive_processing) { // evacuation always takes place at a safepoint; for concurrent iterations, we skip derived pointers, which is ok b/c coarse card marking is used for chunks
-      if (concurrent_gc) {
-        _chunk->set_gc_mode(true);
-        OrderAccess::storestore(); // if you see any following writes, you'll see this
+      assert (!f.is_compiled() || f.oopmap()->has_derived_oops() == f.oopmap()->has_any(OopMapValue::derived_oop_value), "");
+      if (f.is_compiled() && f.oopmap()->has_derived_oops()) {
+        if (concurrent_gc) {
+          _chunk->set_gc_mode(true);
+          OrderAccess::storestore(); // if you see any following writes, you'll see this
+        }
+        RelativizeDerivedPointers<concurrent_gc> derived_closure;
+        f.iterate_derived_pointers(&derived_closure, map);
       }
-      RelativizeDerivedPointers<concurrent_gc> derived_closure;
-      f.iterate_derived_pointers(&derived_closure, map);
     }
 
     CheckMutationWrapper<OopClosureType> cl(_closure, _chunk);

src/hotspot/share/opto/buildOopMap.cpp

@@ -378,11 +378,13 @@ OopMap *OopFlow::build_oop_map( Node *n, int max_reg, PhaseRegAlloc *regalloc, i
 #endif
 
 #ifdef ASSERT
+  bool has_derived_oops = false;
   for( OopMapStream oms1(omap); !oms1.is_done(); oms1.next()) {
     OopMapValue omv1 = oms1.current();
     if (omv1.type() != OopMapValue::derived_oop_value) {
       continue;
     }
+    has_derived_oops = true;
     bool found = false;
     for( OopMapStream oms2(omap); !oms2.is_done(); oms2.next()) {
       OopMapValue omv2 = oms2.current();
@@ -394,6 +396,7 @@ OopMap *OopFlow::build_oop_map( Node *n, int max_reg, PhaseRegAlloc *regalloc, i
         break;
       }
     }
+    assert(has_derived_oops == omap->has_derived_oops(), "");
     assert( found, "derived with no base in oopmap" );
   }