src/share/vm/ci/ciMethodData.cpp

rev 9358 : 8057038: Speculative traps not robust when compilation and class unloading are concurrent
Summary: speculative traps can be removed from MDO while being copied by compiler
Reviewed-by: kvn, iveresov

*** 79,101 ****
  }
  
  void ciMethodData::load_extra_data() {
    MethodData* mdo = get_MethodData();
  
    // speculative trap entries also hold a pointer to a Method so need to be translated
    DataLayout* dp_src  = mdo->extra_data_base();
!   DataLayout* end_src = mdo->extra_data_limit();
    DataLayout* dp_dst  = extra_data_base();
    for (;; dp_src = MethodData::next_extra(dp_src), dp_dst = MethodData::next_extra(dp_dst)) {
      assert(dp_src < end_src, "moved past end of extra data");
!     // New traps in the MDO can be added as we translate the copy so
!     // look at the entries in the copy.
!     switch(dp_dst->tag()) {
      case DataLayout::speculative_trap_data_tag: {
        ciSpeculativeTrapData* data_dst = new ciSpeculativeTrapData(dp_dst);
        SpeculativeTrapData* data_src = new SpeculativeTrapData(dp_src);
        data_dst->translate_from(data_src);
        break;
      }
      case DataLayout::bit_data_tag:
        break;
      case DataLayout::no_tag:
--- 79,119 ----
  }
  
  void ciMethodData::load_extra_data() {
    MethodData* mdo = get_MethodData();
  
+   MutexLocker(mdo->extra_data_lock());
+ 
    // speculative trap entries also hold a pointer to a Method so need to be translated
    DataLayout* dp_src  = mdo->extra_data_base();
!   DataLayout* end_src = mdo->args_data_limit();
    DataLayout* dp_dst  = extra_data_base();
    for (;; dp_src = MethodData::next_extra(dp_src), dp_dst = MethodData::next_extra(dp_dst)) {
      assert(dp_src < end_src, "moved past end of extra data");
!     assert(((intptr_t)dp_dst) - ((intptr_t)extra_data_base()) == ((intptr_t)dp_src) - ((intptr_t)mdo->extra_data_base()), "source and destination don't match");
!     // New traps in the MDO may have been added since we copied the
!     // data (concurrent deoptimizations before we acquired
!     // extra_data_lock above) or can be removed (a safepoint may occur
!     // in the translate_from call below) as we translate the copy:
!     // update the copy as we go.
!     int tag = dp_src->tag();
!     if (tag != DataLayout::arg_info_data_tag) {
!       memcpy(dp_dst, dp_src, ((intptr_t)MethodData::next_extra(dp_src)) - ((intptr_t)dp_src));
!     }
! 
!     switch(tag) {
      case DataLayout::speculative_trap_data_tag: {
        ciSpeculativeTrapData* data_dst = new ciSpeculativeTrapData(dp_dst);
        SpeculativeTrapData* data_src = new SpeculativeTrapData(dp_src);
+ 
        data_dst->translate_from(data_src);
+ 
+ #ifdef ASSERT
+       SpeculativeTrapData* data_src2 = new SpeculativeTrapData(dp_src);
+       assert(data_src2->method() == data_src->method() && data_src2->bci() == data_src->bci(), "entries changed while translating");
+ #endif
+ 
        break;
      }
      case DataLayout::bit_data_tag:
        break;
      case DataLayout::no_tag:
*** 242,254 ****
    ciProfileData* next = data_at(next_index);
    return next;
  }
  
  ciProfileData* ciMethodData::bci_to_extra_data(int bci, ciMethod* m, bool& two_free_slots) {
!   // bci_to_extra_data(bci) ...
!   DataLayout* dp  = data_layout_at(data_size());
!   DataLayout* end = data_layout_at(data_size() + extra_data_size());
    two_free_slots = false;
    for (;dp < end; dp = MethodData::next_extra(dp)) {
      switch(dp->tag()) {
      case DataLayout::no_tag:
        _saw_free_extra_data = true;  // observed an empty slot (common case)
--- 260,271 ----
    ciProfileData* next = data_at(next_index);
    return next;
  }
  
  ciProfileData* ciMethodData::bci_to_extra_data(int bci, ciMethod* m, bool& two_free_slots) {
!   DataLayout* dp  = extra_data_base();
!   DataLayout* end = args_data_limit();
    two_free_slots = false;
    for (;dp < end; dp = MethodData::next_extra(dp)) {
      switch(dp->tag()) {
      case DataLayout::no_tag:
        _saw_free_extra_data = true;  // observed an empty slot (common case)
*** 495,506 ****
    return in_ByteSize(offset);
  }
  
  ciArgInfoData *ciMethodData::arg_info() const {
    // Should be last, have to skip all traps.
!   DataLayout* dp  = data_layout_at(data_size());
!   DataLayout* end = data_layout_at(data_size() + extra_data_size());
    for (; dp < end; dp = MethodData::next_extra(dp)) {
      if (dp->tag() == DataLayout::arg_info_data_tag)
        return new ciArgInfoData(dp);
    }
    return NULL;
--- 512,523 ----
    return in_ByteSize(offset);
  }
  
  ciArgInfoData *ciMethodData::arg_info() const {
    // Should be last, have to skip all traps.
!   DataLayout* dp  = extra_data_base();
!   DataLayout* end = args_data_limit();
    for (; dp < end; dp = MethodData::next_extra(dp)) {
      if (dp->tag() == DataLayout::arg_info_data_tag)
        return new ciArgInfoData(dp);
    }
    return NULL;
*** 597,608 ****
      st->print("%d", dp_to_di(data->dp()));
      st->fill_to(6);
      data->print_data_on(st);
    }
    st->print_cr("--- Extra data:");
!   DataLayout* dp  = data_layout_at(data_size());
!   DataLayout* end = data_layout_at(data_size() + extra_data_size());
    for (;; dp = MethodData::next_extra(dp)) {
      assert(dp < end, "moved past end of extra data");
      switch (dp->tag()) {
      case DataLayout::no_tag:
        continue;
--- 614,625 ----
      st->print("%d", dp_to_di(data->dp()));
      st->fill_to(6);
      data->print_data_on(st);
    }
    st->print_cr("--- Extra data:");
!   DataLayout* dp  = extra_data_base();
!   DataLayout* end = args_data_limit();
    for (;; dp = MethodData::next_extra(dp)) {
      assert(dp < end, "moved past end of extra data");
      switch (dp->tag()) {
      case DataLayout::no_tag:
        continue;