Merge

hotspot/src/share/vm/code/codeCache.cpp

@@ -124,7 +124,6 @@ int CodeCache::_number_of_nmethods = 0;
 int CodeCache::_number_of_nmethods_with_dependencies = 0;
 bool CodeCache::_needs_cache_clean = false;
 nmethod* CodeCache::_scavenge_root_nmethods = NULL;
-nmethod* CodeCache::_saved_nmethods = NULL;
 
 int CodeCache::_codemem_full_count = 0;
 
@@ -464,96 +463,11 @@ void CodeCache::verify_perm_nmethods(CodeBlobClosure* f_or_null) {
 }
 #endif //PRODUCT
 
-/**
- * Remove and return nmethod from the saved code list in order to reanimate it.
- */
-nmethod* CodeCache::reanimate_saved_code(Method* m) {
-  MutexLockerEx mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
-  nmethod* saved = _saved_nmethods;
-  nmethod* prev = NULL;
-  while (saved != NULL) {
-    if (saved->is_in_use() && saved->method() == m) {
-      if (prev != NULL) {
-        prev->set_saved_nmethod_link(saved->saved_nmethod_link());
-      } else {
-        _saved_nmethods = saved->saved_nmethod_link();
-      }
-      assert(saved->is_speculatively_disconnected(), "shouldn't call for other nmethods");
-      saved->set_speculatively_disconnected(false);
-      saved->set_saved_nmethod_link(NULL);
-      if (PrintMethodFlushing) {
-        saved->print_on(tty, " ### nmethod is reconnected");
-      }
-      if (LogCompilation && (xtty != NULL)) {
-        ttyLocker ttyl;
-        xtty->begin_elem("nmethod_reconnected compile_id='%3d'", saved->compile_id());
-        xtty->method(m);
-        xtty->stamp();
-        xtty->end_elem();
-      }
-      return saved;
-    }
-    prev = saved;
-    saved = saved->saved_nmethod_link();
-  }
-  return NULL;
-}
-
-/**
- * Remove nmethod from the saved code list in order to discard it permanently
- */
-void CodeCache::remove_saved_code(nmethod* nm) {
-  // For conc swpr this will be called with CodeCache_lock taken by caller
-  assert_locked_or_safepoint(CodeCache_lock);
-  assert(nm->is_speculatively_disconnected(), "shouldn't call for other nmethods");
-  nmethod* saved = _saved_nmethods;
-  nmethod* prev = NULL;
-  while (saved != NULL) {
-    if (saved == nm) {
-      if (prev != NULL) {
-        prev->set_saved_nmethod_link(saved->saved_nmethod_link());
-      } else {
-        _saved_nmethods = saved->saved_nmethod_link();
-      }
-      if (LogCompilation && (xtty != NULL)) {
-        ttyLocker ttyl;
-        xtty->begin_elem("nmethod_removed compile_id='%3d'", nm->compile_id());
-        xtty->stamp();
-        xtty->end_elem();
-      }
-      return;
-    }
-    prev = saved;
-    saved = saved->saved_nmethod_link();
-  }
-  ShouldNotReachHere();
-}
-
-void CodeCache::speculatively_disconnect(nmethod* nm) {
-  assert_locked_or_safepoint(CodeCache_lock);
-  assert(nm->is_in_use() && !nm->is_speculatively_disconnected(), "should only disconnect live nmethods");
-  nm->set_saved_nmethod_link(_saved_nmethods);
-  _saved_nmethods = nm;
-  if (PrintMethodFlushing) {
-    nm->print_on(tty, " ### nmethod is speculatively disconnected");
-  }
-  if (LogCompilation && (xtty != NULL)) {
-    ttyLocker ttyl;
-    xtty->begin_elem("nmethod_disconnected compile_id='%3d'", nm->compile_id());
-    xtty->method(nm->method());
-    xtty->stamp();
-    xtty->end_elem();
-  }
-  nm->method()->clear_code();
-  nm->set_speculatively_disconnected(true);
-}
-
 
 void CodeCache::gc_prologue() {
   assert(!nmethod::oops_do_marking_is_active(), "oops_do_marking_epilogue must be called");
 }
 
-
 void CodeCache::gc_epilogue() {
   assert_locked_or_safepoint(CodeCache_lock);
   FOR_ALL_ALIVE_BLOBS(cb) {

hotspot/src/share/vm/code/codeCache.hpp

@@ -57,7 +57,6 @@ class CodeCache : AllStatic {
   static int _number_of_nmethods_with_dependencies;
   static bool _needs_cache_clean;
   static nmethod* _scavenge_root_nmethods;  // linked via nm->scavenge_root_link()
-  static nmethod* _saved_nmethods;          // Linked list of speculatively disconnected nmethods.
 
   static void verify_if_often() PRODUCT_RETURN;
 
@@ -167,17 +166,12 @@ class CodeCache : AllStatic {
   static size_t  capacity()                      { return _heap->capacity(); }
   static size_t  max_capacity()                  { return _heap->max_capacity(); }
   static size_t  unallocated_capacity()          { return _heap->unallocated_capacity(); }
-  static bool    needs_flushing()                { return unallocated_capacity() < CodeCacheFlushingMinimumFreeSpace; }
   static double  reverse_free_ratio();
 
   static bool needs_cache_clean()                { return _needs_cache_clean; }
   static void set_needs_cache_clean(bool v)      { _needs_cache_clean = v;    }
   static void clear_inline_caches();             // clear all inline caches
 
-  static nmethod* reanimate_saved_code(Method* m);
-  static void remove_saved_code(nmethod* nm);
-  static void speculatively_disconnect(nmethod* nm);
-
   // Deoptimization
   static int  mark_for_deoptimization(DepChange& changes);
 #ifdef HOTSWAP

hotspot/src/share/vm/code/nmethod.cpp

@@ -462,7 +462,6 @@ void nmethod::init_defaults() {
   _state                      = alive;
   _marked_for_reclamation     = 0;
   _has_flushed_dependencies   = 0;
-  _speculatively_disconnected = 0;
   _has_unsafe_access          = 0;
   _has_method_handle_invokes  = 0;
   _lazy_critical_native       = 0;
@@ -481,7 +480,6 @@ void nmethod::init_defaults() {
   _osr_link                = NULL;
   _scavenge_root_link      = NULL;
   _scavenge_root_state     = 0;
-  _saved_nmethod_link      = NULL;
   _compiler                = NULL;
 
 #ifdef HAVE_DTRACE_H
@@ -686,6 +684,7 @@ nmethod::nmethod(
     _osr_entry_point         = NULL;
     _exception_cache         = NULL;
     _pc_desc_cache.reset_to(NULL);
+    _hotness_counter         = NMethodSweeper::hotness_counter_reset_val();
 
     code_buffer->copy_values_to(this);
     if (ScavengeRootsInCode && detect_scavenge_root_oops()) {
@@ -770,6 +769,7 @@ nmethod::nmethod(
     _osr_entry_point         = NULL;
     _exception_cache         = NULL;
     _pc_desc_cache.reset_to(NULL);
+    _hotness_counter         = NMethodSweeper::hotness_counter_reset_val();
 
     code_buffer->copy_values_to(this);
     debug_only(verify_scavenge_root_oops());
@@ -842,6 +842,7 @@ nmethod::nmethod(
     _comp_level              = comp_level;
     _compiler                = compiler;
     _orig_pc_offset          = orig_pc_offset;
+    _hotness_counter         = NMethodSweeper::hotness_counter_reset_val();
 
     // Section offsets
     _consts_offset           = content_offset()      + code_buffer->total_offset_of(code_buffer->consts());
@@ -1176,7 +1177,7 @@ void nmethod::cleanup_inline_caches() {
 
 // This is a private interface with the sweeper.
 void nmethod::mark_as_seen_on_stack() {
-  assert(is_not_entrant(), "must be a non-entrant method");
+  assert(is_alive(), "Must be an alive method");
   // Set the traversal mark to ensure that the sweeper does 2
   // cleaning passes before moving to zombie.
   set_stack_traversal_mark(NMethodSweeper::traversal_count());
@@ -1261,7 +1262,7 @@ void nmethod::make_unloaded(BoolObjectClosure* is_alive, oop cause) {
 
   set_osr_link(NULL);
   //set_scavenge_root_link(NULL); // done by prune_scavenge_root_nmethods
-  NMethodSweeper::notify(this);
+  NMethodSweeper::notify();
 }
 
 void nmethod::invalidate_osr_method() {
@@ -1351,6 +1352,15 @@ bool nmethod::make_not_entrant_or_zombie(unsigned int state) {
       nmethod_needs_unregister = true;
     }
 
+    // Must happen before state change. Otherwise we have a race condition in
+    // nmethod::can_not_entrant_be_converted(). I.e., a method can immediately
+    // transition its state from 'not_entrant' to 'zombie' without having to wait
+    // for stack scanning.
+    if (state == not_entrant) {
+      mark_as_seen_on_stack();
+      OrderAccess::storestore();
+    }
+
     // Change state
     _state = state;
 
@@ -1369,11 +1379,6 @@ bool nmethod::make_not_entrant_or_zombie(unsigned int state) {
       HandleMark hm;
       method()->clear_code();
     }
-
-    if (state == not_entrant) {
-      mark_as_seen_on_stack();
-    }
-
   } // leave critical region under Patching_lock
 
   // When the nmethod becomes zombie it is no longer alive so the
@@ -1416,7 +1421,7 @@ bool nmethod::make_not_entrant_or_zombie(unsigned int state) {
   }
 
   // Make sweeper aware that there is a zombie method that needs to be removed
-  NMethodSweeper::notify(this);
+  NMethodSweeper::notify();
 
   return true;
 }
@@ -1451,10 +1456,6 @@ void nmethod::flush() {
     CodeCache::drop_scavenge_root_nmethod(this);
   }
 
-  if (is_speculatively_disconnected()) {
-    CodeCache::remove_saved_code(this);
-  }
-
 #ifdef SHARK
   ((SharkCompiler *) compiler())->free_compiled_method(insts_begin());
 #endif // SHARK

hotspot/src/share/vm/code/nmethod.hpp

@@ -119,7 +119,6 @@ class nmethod : public CodeBlob {
   // To support simple linked-list chaining of nmethods:
   nmethod*  _osr_link;         // from InstanceKlass::osr_nmethods_head
   nmethod*  _scavenge_root_link; // from CodeCache::scavenge_root_nmethods
-  nmethod*  _saved_nmethod_link; // from CodeCache::speculatively_disconnect
 
   static nmethod* volatile _oops_do_mark_nmethods;
   nmethod*        volatile _oops_do_mark_link;
@@ -165,7 +164,6 @@ class nmethod : public CodeBlob {
 
   // protected by CodeCache_lock
   bool _has_flushed_dependencies;            // Used for maintenance of dependencies (CodeCache_lock)
-  bool _speculatively_disconnected;          // Marked for potential unload
 
   bool _marked_for_reclamation;              // Used by NMethodSweeper (set only by sweeper)
   bool _marked_for_deoptimization;           // Used for stack deoptimization
@@ -180,7 +178,7 @@ class nmethod : public CodeBlob {
   unsigned int _has_wide_vectors:1;          // Preserve wide vectors at safepoints
 
   // Protected by Patching_lock
-  unsigned char _state;                      // {alive, not_entrant, zombie, unloaded}
+  volatile unsigned char _state;             // {alive, not_entrant, zombie, unloaded}
 
 #ifdef ASSERT
   bool _oops_are_stale;  // indicates that it's no longer safe to access oops section
@@ -202,11 +200,18 @@ class nmethod : public CodeBlob {
 
   // not_entrant method removal. Each mark_sweep pass will update
   // this mark to current sweep invocation count if it is seen on the
-  // stack.  An not_entrant method can be removed when there is no
+  // stack.  An not_entrant method can be removed when there are no
   // more activations, i.e., when the _stack_traversal_mark is less than
   // current sweep traversal index.
   long _stack_traversal_mark;
 
+  // The _hotness_counter indicates the hotness of a method. The higher
+  // the value the hotter the method. The hotness counter of a nmethod is
+  // set to [(ReservedCodeCacheSize / (1024 * 1024)) * 2] each time the method
+  // is active while stack scanning (mark_active_nmethods()). The hotness
+  // counter is decreased (by 1) while sweeping.
+  int _hotness_counter;
+
   ExceptionCache *_exception_cache;
   PcDescCache     _pc_desc_cache;
 
@@ -382,6 +387,10 @@ class nmethod : public CodeBlob {
 
   int total_size        () const;
 
+  void dec_hotness_counter()        { _hotness_counter--; }
+  void set_hotness_counter(int val) { _hotness_counter = val; }
+  int  hotness_counter() const      { return _hotness_counter; }
+
   // Containment
   bool consts_contains       (address addr) const { return consts_begin       () <= addr && addr < consts_end       (); }
   bool insts_contains        (address addr) const { return insts_begin        () <= addr && addr < insts_end        (); }
@@ -408,8 +417,8 @@ class nmethod : public CodeBlob {
   // alive.  It is used when an uncommon trap happens.  Returns true
   // if this thread changed the state of the nmethod or false if
   // another thread performed the transition.
-  bool  make_not_entrant()                        { return make_not_entrant_or_zombie(not_entrant); }
-  bool  make_zombie()                             { return make_not_entrant_or_zombie(zombie); }
+  bool  make_not_entrant() { return make_not_entrant_or_zombie(not_entrant); }
+  bool  make_zombie()      { return make_not_entrant_or_zombie(zombie); }
 
   // used by jvmti to track if the unload event has been reported
   bool  unload_reported()                         { return _unload_reported; }
@@ -437,9 +446,6 @@ class nmethod : public CodeBlob {
   bool  has_method_handle_invokes() const         { return _has_method_handle_invokes; }
   void  set_has_method_handle_invokes(bool z)     { _has_method_handle_invokes = z; }
 
-  bool  is_speculatively_disconnected() const     { return _speculatively_disconnected; }
-  void  set_speculatively_disconnected(bool z)    { _speculatively_disconnected = z; }
-
   bool  is_lazy_critical_native() const           { return _lazy_critical_native; }
   void  set_lazy_critical_native(bool z)          { _lazy_critical_native = z; }
 
@@ -499,9 +505,6 @@ public:
   nmethod* scavenge_root_link() const                  { return _scavenge_root_link; }
   void     set_scavenge_root_link(nmethod *n)          { _scavenge_root_link = n; }
 
-  nmethod* saved_nmethod_link() const                  { return _saved_nmethod_link; }
-  void     set_saved_nmethod_link(nmethod *n)          { _saved_nmethod_link = n; }
-
  public:
 
   // Sweeper support