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hotspot/src/share/vm/oops/methodDataOop.cpp

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+/*
+ * Copyright 2000-2007 Sun Microsystems, Inc.  All Rights Reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ *
+ */
+
+# include "incls/_precompiled.incl"
+# include "incls/_methodDataOop.cpp.incl"
+
+// ==================================================================
+// DataLayout
+//
+// Overlay for generic profiling data.
+
+// Some types of data layouts need a length field.
+bool DataLayout::needs_array_len(u1 tag) {
+  return (tag == multi_branch_data_tag);
+}
+
+// Perform generic initialization of the data.  More specific
+// initialization occurs in overrides of ProfileData::post_initialize.
+void DataLayout::initialize(u1 tag, u2 bci, int cell_count) {
+  _header._bits = (intptr_t)0;
+  _header._struct._tag = tag;
+  _header._struct._bci = bci;
+  for (int i = 0; i < cell_count; i++) {
+    set_cell_at(i, (intptr_t)0);
+  }
+  if (needs_array_len(tag)) {
+    set_cell_at(ArrayData::array_len_off_set, cell_count - 1); // -1 for header.
+  }
+}
+
+// ==================================================================
+// ProfileData
+//
+// A ProfileData object is created to refer to a section of profiling
+// data in a structured way.
+
+// Constructor for invalid ProfileData.
+ProfileData::ProfileData() {
+  _data = NULL;
+}
+
+#ifndef PRODUCT
+void ProfileData::print_shared(outputStream* st, const char* name) {
+  st->print("bci: %d", bci());
+  st->fill_to(tab_width_one);
+  st->print("%s", name);
+  tab(st);
+  int trap = trap_state();
+  if (trap != 0) {
+    char buf[100];
+    st->print("trap(%s) ", Deoptimization::format_trap_state(buf, sizeof(buf), trap));
+  }
+  int flags = data()->flags();
+  if (flags != 0)
+    st->print("flags(%d) ", flags);
+}
+
+void ProfileData::tab(outputStream* st) {
+  st->fill_to(tab_width_two);
+}
+#endif // !PRODUCT
+
+// ==================================================================
+// BitData
+//
+// A BitData corresponds to a one-bit flag.  This is used to indicate
+// whether a checkcast bytecode has seen a null value.
+
+
+#ifndef PRODUCT
+void BitData::print_data_on(outputStream* st) {
+  print_shared(st, "BitData");
+}
+#endif // !PRODUCT
+
+// ==================================================================
+// CounterData
+//
+// A CounterData corresponds to a simple counter.
+
+#ifndef PRODUCT
+void CounterData::print_data_on(outputStream* st) {
+  print_shared(st, "CounterData");
+  st->print_cr("count(%u)", count());
+}
+#endif // !PRODUCT
+
+// ==================================================================
+// JumpData
+//
+// A JumpData is used to access profiling information for a direct
+// branch.  It is a counter, used for counting the number of branches,
+// plus a data displacement, used for realigning the data pointer to
+// the corresponding target bci.
+
+void JumpData::post_initialize(BytecodeStream* stream, methodDataOop mdo) {
+  assert(stream->bci() == bci(), "wrong pos");
+  int target;
+  Bytecodes::Code c = stream->code();
+  if (c == Bytecodes::_goto_w || c == Bytecodes::_jsr_w) {
+    target = stream->dest_w();
+  } else {
+    target = stream->dest();
+  }
+  int my_di = mdo->dp_to_di(dp());
+  int target_di = mdo->bci_to_di(target);
+  int offset = target_di - my_di;
+  set_displacement(offset);
+}
+
+#ifndef PRODUCT
+void JumpData::print_data_on(outputStream* st) {
+  print_shared(st, "JumpData");
+  st->print_cr("taken(%u) displacement(%d)", taken(), displacement());
+}
+#endif // !PRODUCT
+
+// ==================================================================
+// ReceiverTypeData
+//
+// A ReceiverTypeData is used to access profiling information about a
+// dynamic type check.  It consists of a counter which counts the total times
+// that the check is reached, and a series of (klassOop, count) pairs
+// which are used to store a type profile for the receiver of the check.
+
+void ReceiverTypeData::follow_contents() {
+  for (uint row = 0; row < row_limit(); row++) {
+    if (receiver(row) != NULL) {
+      MarkSweep::mark_and_push(adr_receiver(row));
+    }
+  }
+}
+
+#ifndef SERIALGC
+void ReceiverTypeData::follow_contents(ParCompactionManager* cm) {
+  for (uint row = 0; row < row_limit(); row++) {
+    if (receiver(row) != NULL) {
+      PSParallelCompact::mark_and_push(cm, adr_receiver(row));
+    }
+  }
+}
+#endif // SERIALGC
+
+void ReceiverTypeData::oop_iterate(OopClosure* blk) {
+  for (uint row = 0; row < row_limit(); row++) {
+    if (receiver(row) != NULL) {
+      blk->do_oop(adr_receiver(row));
+    }
+  }
+}
+
+void ReceiverTypeData::oop_iterate_m(OopClosure* blk, MemRegion mr) {
+  for (uint row = 0; row < row_limit(); row++) {
+    if (receiver(row) != NULL) {
+      oop* adr = adr_receiver(row);
+      if (mr.contains(adr)) {
+        blk->do_oop(adr);
+      }
+    }
+  }
+}
+
+void ReceiverTypeData::adjust_pointers() {
+  for (uint row = 0; row < row_limit(); row++) {
+    if (receiver(row) != NULL) {
+      MarkSweep::adjust_pointer(adr_receiver(row));
+    }
+  }
+}
+
+#ifndef SERIALGC
+void ReceiverTypeData::update_pointers() {
+  for (uint row = 0; row < row_limit(); row++) {
+    if (receiver_unchecked(row) != NULL) {
+      PSParallelCompact::adjust_pointer(adr_receiver(row));
+    }
+  }
+}
+
+void ReceiverTypeData::update_pointers(HeapWord* beg_addr, HeapWord* end_addr) {
+  // The loop bounds could be computed based on beg_addr/end_addr and the
+  // boundary test hoisted outside the loop (see klassVTable for an example);
+  // however, row_limit() is small enough (2) to make that less efficient.
+  for (uint row = 0; row < row_limit(); row++) {
+    if (receiver_unchecked(row) != NULL) {
+      PSParallelCompact::adjust_pointer(adr_receiver(row), beg_addr, end_addr);
+    }
+  }
+}
+#endif // SERIALGC
+
+#ifndef PRODUCT
+void ReceiverTypeData::print_receiver_data_on(outputStream* st) {
+  uint row;
+  int entries = 0;
+  for (row = 0; row < row_limit(); row++) {
+    if (receiver(row) != NULL)  entries++;
+  }
+  st->print_cr("count(%u) entries(%u)", count(), entries);
+  for (row = 0; row < row_limit(); row++) {
+    if (receiver(row) != NULL) {
+      tab(st);
+      receiver(row)->print_value_on(st);
+      st->print_cr("(%u)", receiver_count(row));
+    }
+  }
+}
+void ReceiverTypeData::print_data_on(outputStream* st) {
+  print_shared(st, "ReceiverTypeData");
+  print_receiver_data_on(st);
+}
+void VirtualCallData::print_data_on(outputStream* st) {
+  print_shared(st, "VirtualCallData");
+  print_receiver_data_on(st);
+}
+#endif // !PRODUCT
+
+// ==================================================================
+// RetData
+//
+// A RetData is used to access profiling information for a ret bytecode.
+// It is composed of a count of the number of times that the ret has
+// been executed, followed by a series of triples of the form
+// (bci, count, di) which count the number of times that some bci was the
+// target of the ret and cache a corresponding displacement.
+
+void RetData::post_initialize(BytecodeStream* stream, methodDataOop mdo) {
+  for (uint row = 0; row < row_limit(); row++) {
+    set_bci_displacement(row, -1);
+    set_bci(row, no_bci);
+  }
+  // release so other threads see a consistent state.  bci is used as
+  // a valid flag for bci_displacement.
+  OrderAccess::release();
+}
+
+// This routine needs to atomically update the RetData structure, so the
+// caller needs to hold the RetData_lock before it gets here.  Since taking
+// the lock can block (and allow GC) and since RetData is a ProfileData is a
+// wrapper around a derived oop, taking the lock in _this_ method will
+// basically cause the 'this' pointer's _data field to contain junk after the
+// lock.  We require the caller to take the lock before making the ProfileData
+// structure.  Currently the only caller is InterpreterRuntime::update_mdp_for_ret
+address RetData::fixup_ret(int return_bci, methodDataHandle h_mdo) {
+  // First find the mdp which corresponds to the return bci.
+  address mdp = h_mdo->bci_to_dp(return_bci);
+
+  // Now check to see if any of the cache slots are open.
+  for (uint row = 0; row < row_limit(); row++) {
+    if (bci(row) == no_bci) {
+      set_bci_displacement(row, mdp - dp());
+      set_bci_count(row, DataLayout::counter_increment);
+      // Barrier to ensure displacement is written before the bci; allows
+      // the interpreter to read displacement without fear of race condition.
+      release_set_bci(row, return_bci);
+      break;
+    }
+  }
+  return mdp;
+}
+
+
+#ifndef PRODUCT
+void RetData::print_data_on(outputStream* st) {
+  print_shared(st, "RetData");
+  uint row;
+  int entries = 0;
+  for (row = 0; row < row_limit(); row++) {
+    if (bci(row) != no_bci)  entries++;
+  }
+  st->print_cr("count(%u) entries(%u)", count(), entries);
+  for (row = 0; row < row_limit(); row++) {
+    if (bci(row) != no_bci) {
+      tab(st);
+      st->print_cr("bci(%d: count(%u) displacement(%d))",
+                   bci(row), bci_count(row), bci_displacement(row));
+    }
+  }
+}
+#endif // !PRODUCT
+
+// ==================================================================
+// BranchData
+//
+// A BranchData is used to access profiling data for a two-way branch.
+// It consists of taken and not_taken counts as well as a data displacement
+// for the taken case.
+
+void BranchData::post_initialize(BytecodeStream* stream, methodDataOop mdo) {
+  assert(stream->bci() == bci(), "wrong pos");
+  int target = stream->dest();
+  int my_di = mdo->dp_to_di(dp());
+  int target_di = mdo->bci_to_di(target);
+  int offset = target_di - my_di;
+  set_displacement(offset);
+}
+
+#ifndef PRODUCT
+void BranchData::print_data_on(outputStream* st) {
+  print_shared(st, "BranchData");
+  st->print_cr("taken(%u) displacement(%d)",
+               taken(), displacement());
+  tab(st);
+  st->print_cr("not taken(%u)", not_taken());
+}
+#endif
+
+// ==================================================================
+// MultiBranchData
+//
+// A MultiBranchData is used to access profiling information for
+// a multi-way branch (*switch bytecodes).  It consists of a series
+// of (count, displacement) pairs, which count the number of times each
+// case was taken and specify the data displacment for each branch target.
+
+int MultiBranchData::compute_cell_count(BytecodeStream* stream) {
+  int cell_count = 0;
+  if (stream->code() == Bytecodes::_tableswitch) {
+    Bytecode_tableswitch* sw = Bytecode_tableswitch_at(stream->bcp());
+    cell_count = 1 + per_case_cell_count * (1 + sw->length()); // 1 for default
+  } else {
+    Bytecode_lookupswitch* sw = Bytecode_lookupswitch_at(stream->bcp());
+    cell_count = 1 + per_case_cell_count * (sw->number_of_pairs() + 1); // 1 for default
+  }
+  return cell_count;
+}
+
+void MultiBranchData::post_initialize(BytecodeStream* stream,
+                                      methodDataOop mdo) {
+  assert(stream->bci() == bci(), "wrong pos");
+  int target;
+  int my_di;
+  int target_di;
+  int offset;
+  if (stream->code() == Bytecodes::_tableswitch) {
+    Bytecode_tableswitch* sw = Bytecode_tableswitch_at(stream->bcp());
+    int len = sw->length();
+    assert(array_len() == per_case_cell_count * (len + 1), "wrong len");
+    for (int count = 0; count < len; count++) {
+      target = sw->dest_offset_at(count) + bci();
+      my_di = mdo->dp_to_di(dp());
+      target_di = mdo->bci_to_di(target);
+      offset = target_di - my_di;
+      set_displacement_at(count, offset);
+    }
+    target = sw->default_offset() + bci();
+    my_di = mdo->dp_to_di(dp());
+    target_di = mdo->bci_to_di(target);
+    offset = target_di - my_di;
+    set_default_displacement(offset);
+
+  } else {
+    Bytecode_lookupswitch* sw = Bytecode_lookupswitch_at(stream->bcp());
+    int npairs = sw->number_of_pairs();
+    assert(array_len() == per_case_cell_count * (npairs + 1), "wrong len");
+    for (int count = 0; count < npairs; count++) {
+      LookupswitchPair *pair = sw->pair_at(count);
+      target = pair->offset() + bci();
+      my_di = mdo->dp_to_di(dp());
+      target_di = mdo->bci_to_di(target);
+      offset = target_di - my_di;
+      set_displacement_at(count, offset);
+    }
+    target = sw->default_offset() + bci();
+    my_di = mdo->dp_to_di(dp());
+    target_di = mdo->bci_to_di(target);
+    offset = target_di - my_di;
+    set_default_displacement(offset);
+  }
+}
+
+#ifndef PRODUCT
+void MultiBranchData::print_data_on(outputStream* st) {
+  print_shared(st, "MultiBranchData");
+  st->print_cr("default_count(%u) displacement(%d)",
+               default_count(), default_displacement());
+  int cases = number_of_cases();
+  for (int i = 0; i < cases; i++) {
+    tab(st);
+    st->print_cr("count(%u) displacement(%d)",
+                 count_at(i), displacement_at(i));
+  }
+}
+#endif
+
+// ==================================================================
+// methodDataOop
+//
+// A methodDataOop holds information which has been collected about
+// a method.
+
+int methodDataOopDesc::bytecode_cell_count(Bytecodes::Code code) {
+  switch (code) {
+  case Bytecodes::_checkcast:
+  case Bytecodes::_instanceof:
+  case Bytecodes::_aastore:
+    if (TypeProfileCasts) {
+      return ReceiverTypeData::static_cell_count();
+    } else {
+      return BitData::static_cell_count();
+    }
+  case Bytecodes::_invokespecial:
+  case Bytecodes::_invokestatic:
+    return CounterData::static_cell_count();
+  case Bytecodes::_goto:
+  case Bytecodes::_goto_w:
+  case Bytecodes::_jsr:
+  case Bytecodes::_jsr_w:
+    return JumpData::static_cell_count();
+  case Bytecodes::_invokevirtual:
+  case Bytecodes::_invokeinterface:
+    return VirtualCallData::static_cell_count();
+  case Bytecodes::_ret:
+    return RetData::static_cell_count();
+  case Bytecodes::_ifeq:
+  case Bytecodes::_ifne:
+  case Bytecodes::_iflt:
+  case Bytecodes::_ifge:
+  case Bytecodes::_ifgt:
+  case Bytecodes::_ifle:
+  case Bytecodes::_if_icmpeq:
+  case Bytecodes::_if_icmpne:
+  case Bytecodes::_if_icmplt:
+  case Bytecodes::_if_icmpge:
+  case Bytecodes::_if_icmpgt:
+  case Bytecodes::_if_icmple:
+  case Bytecodes::_if_acmpeq:
+  case Bytecodes::_if_acmpne:
+  case Bytecodes::_ifnull:
+  case Bytecodes::_ifnonnull:
+    return BranchData::static_cell_count();
+  case Bytecodes::_lookupswitch:
+  case Bytecodes::_tableswitch:
+    return variable_cell_count;
+  }
+  return no_profile_data;
+}
+
+// Compute the size of the profiling information corresponding to
+// the current bytecode.
+int methodDataOopDesc::compute_data_size(BytecodeStream* stream) {
+  int cell_count = bytecode_cell_count(stream->code());
+  if (cell_count == no_profile_data) {
+    return 0;
+  }
+  if (cell_count == variable_cell_count) {
+    cell_count = MultiBranchData::compute_cell_count(stream);
+  }
+  // Note:  cell_count might be zero, meaning that there is just
+  //        a DataLayout header, with no extra cells.
+  assert(cell_count >= 0, "sanity");
+  return DataLayout::compute_size_in_bytes(cell_count);
+}
+
+int methodDataOopDesc::compute_extra_data_count(int data_size, int empty_bc_count) {
+  if (ProfileTraps) {
+    // Assume that up to 3% of BCIs with no MDP will need to allocate one.
+    int extra_data_count = (uint)(empty_bc_count * 3) / 128 + 1;
+    // If the method is large, let the extra BCIs grow numerous (to ~1%).
+    int one_percent_of_data
+      = (uint)data_size / (DataLayout::header_size_in_bytes()*128);
+    if (extra_data_count < one_percent_of_data)
+      extra_data_count = one_percent_of_data;
+    if (extra_data_count > empty_bc_count)
+      extra_data_count = empty_bc_count;  // no need for more
+    return extra_data_count;
+  } else {
+    return 0;
+  }
+}
+
+// Compute the size of the methodDataOop necessary to store
+// profiling information about a given method.  Size is in bytes.
+int methodDataOopDesc::compute_allocation_size_in_bytes(methodHandle method) {
+  int data_size = 0;
+  BytecodeStream stream(method);
+  Bytecodes::Code c;
+  int empty_bc_count = 0;  // number of bytecodes lacking data
+  while ((c = stream.next()) >= 0) {
+    int size_in_bytes = compute_data_size(&stream);
+    data_size += size_in_bytes;
+    if (size_in_bytes == 0)  empty_bc_count += 1;
+  }
+  int object_size = in_bytes(data_offset()) + data_size;
+
+  // Add some extra DataLayout cells (at least one) to track stray traps.
+  int extra_data_count = compute_extra_data_count(data_size, empty_bc_count);
+  object_size += extra_data_count * DataLayout::compute_size_in_bytes(0);
+
+  return object_size;
+}
+
+// Compute the size of the methodDataOop necessary to store
+// profiling information about a given method.  Size is in words
+int methodDataOopDesc::compute_allocation_size_in_words(methodHandle method) {
+  int byte_size = compute_allocation_size_in_bytes(method);
+  int word_size = align_size_up(byte_size, BytesPerWord) / BytesPerWord;
+  return align_object_size(word_size);
+}
+
+// Initialize an individual data segment.  Returns the size of
+// the segment in bytes.
+int methodDataOopDesc::initialize_data(BytecodeStream* stream,
+                                       int data_index) {
+  int cell_count = -1;
+  int tag = DataLayout::no_tag;
+  DataLayout* data_layout = data_layout_at(data_index);
+  Bytecodes::Code c = stream->code();
+  switch (c) {
+  case Bytecodes::_checkcast:
+  case Bytecodes::_instanceof:
+  case Bytecodes::_aastore:
+    if (TypeProfileCasts) {
+      cell_count = ReceiverTypeData::static_cell_count();
+      tag = DataLayout::receiver_type_data_tag;
+    } else {
+      cell_count = BitData::static_cell_count();
+      tag = DataLayout::bit_data_tag;
+    }
+    break;
+  case Bytecodes::_invokespecial:
+  case Bytecodes::_invokestatic:
+    cell_count = CounterData::static_cell_count();
+    tag = DataLayout::counter_data_tag;
+    break;
+  case Bytecodes::_goto:
+  case Bytecodes::_goto_w:
+  case Bytecodes::_jsr:
+  case Bytecodes::_jsr_w:
+    cell_count = JumpData::static_cell_count();
+    tag = DataLayout::jump_data_tag;
+    break;
+  case Bytecodes::_invokevirtual:
+  case Bytecodes::_invokeinterface:
+    cell_count = VirtualCallData::static_cell_count();
+    tag = DataLayout::virtual_call_data_tag;
+    break;
+  case Bytecodes::_ret:
+    cell_count = RetData::static_cell_count();
+    tag = DataLayout::ret_data_tag;
+    break;
+  case Bytecodes::_ifeq:
+  case Bytecodes::_ifne:
+  case Bytecodes::_iflt:
+  case Bytecodes::_ifge:
+  case Bytecodes::_ifgt:
+  case Bytecodes::_ifle:
+  case Bytecodes::_if_icmpeq:
+  case Bytecodes::_if_icmpne:
+  case Bytecodes::_if_icmplt:
+  case Bytecodes::_if_icmpge:
+  case Bytecodes::_if_icmpgt:
+  case Bytecodes::_if_icmple:
+  case Bytecodes::_if_acmpeq:
+  case Bytecodes::_if_acmpne:
+  case Bytecodes::_ifnull:
+  case Bytecodes::_ifnonnull:
+    cell_count = BranchData::static_cell_count();
+    tag = DataLayout::branch_data_tag;
+    break;
+  case Bytecodes::_lookupswitch:
+  case Bytecodes::_tableswitch:
+    cell_count = MultiBranchData::compute_cell_count(stream);
+    tag = DataLayout::multi_branch_data_tag;
+    break;
+  }
+  assert(tag == DataLayout::multi_branch_data_tag ||
+         cell_count == bytecode_cell_count(c), "cell counts must agree");
+  if (cell_count >= 0) {
+    assert(tag != DataLayout::no_tag, "bad tag");
+    assert(bytecode_has_profile(c), "agree w/ BHP");
+    data_layout->initialize(tag, stream->bci(), cell_count);
+    return DataLayout::compute_size_in_bytes(cell_count);
+  } else {
+    assert(!bytecode_has_profile(c), "agree w/ !BHP");
+    return 0;
+  }
+}
+
+// Get the data at an arbitrary (sort of) data index.
+ProfileData* methodDataOopDesc::data_at(int data_index) {
+  if (out_of_bounds(data_index)) {
+    return NULL;
+  }
+  DataLayout* data_layout = data_layout_at(data_index);
+
+  switch (data_layout->tag()) {
+  case DataLayout::no_tag:
+  default:
+    ShouldNotReachHere();
+    return NULL;
+  case DataLayout::bit_data_tag:
+    return new BitData(data_layout);
+  case DataLayout::counter_data_tag:
+    return new CounterData(data_layout);
+  case DataLayout::jump_data_tag:
+    return new JumpData(data_layout);
+  case DataLayout::receiver_type_data_tag:
+    return new ReceiverTypeData(data_layout);
+  case DataLayout::virtual_call_data_tag:
+    return new VirtualCallData(data_layout);
+  case DataLayout::ret_data_tag:
+    return new RetData(data_layout);
+  case DataLayout::branch_data_tag:
+    return new BranchData(data_layout);
+  case DataLayout::multi_branch_data_tag:
+    return new MultiBranchData(data_layout);
+  };
+}
+
+// Iteration over data.
+ProfileData* methodDataOopDesc::next_data(ProfileData* current) {
+  int current_index = dp_to_di(current->dp());
+  int next_index = current_index + current->size_in_bytes();
+  ProfileData* next = data_at(next_index);
+  return next;
+}
+
+// Give each of the data entries a chance to perform specific
+// data initialization.
+void methodDataOopDesc::post_initialize(BytecodeStream* stream) {
+  ResourceMark rm;
+  ProfileData* data;
+  for (data = first_data(); is_valid(data); data = next_data(data)) {
+    stream->set_start(data->bci());
+    stream->next();
+    data->post_initialize(stream, this);
+  }
+}
+
+// Initialize the methodDataOop corresponding to a given method.
+void methodDataOopDesc::initialize(methodHandle method) {
+  ResourceMark rm;
+
+  // Set the method back-pointer.
+  _method = method();
+  set_creation_mileage(mileage_of(method()));
+
+  // Initialize flags and trap history.
+  _nof_decompiles = 0;
+  _nof_overflow_recompiles = 0;
+  _nof_overflow_traps = 0;
+  assert(sizeof(_trap_hist) % sizeof(HeapWord) == 0, "align");
+  Copy::zero_to_words((HeapWord*) &_trap_hist,
+                      sizeof(_trap_hist) / sizeof(HeapWord));
+
+  // Go through the bytecodes and allocate and initialize the
+  // corresponding data cells.
+  int data_size = 0;
+  int empty_bc_count = 0;  // number of bytecodes lacking data
+  BytecodeStream stream(method);
+  Bytecodes::Code c;
+  while ((c = stream.next()) >= 0) {
+    int size_in_bytes = initialize_data(&stream, data_size);
+    data_size += size_in_bytes;
+    if (size_in_bytes == 0)  empty_bc_count += 1;
+  }
+  _data_size = data_size;
+  int object_size = in_bytes(data_offset()) + data_size;
+
+  // Add some extra DataLayout cells (at least one) to track stray traps.
+  int extra_data_count = compute_extra_data_count(data_size, empty_bc_count);
+  object_size += extra_data_count * DataLayout::compute_size_in_bytes(0);
+
+  // Set an initial hint. Don't use set_hint_di() because
+  // first_di() may be out of bounds if data_size is 0.
+  // In that situation, _hint_di is never used, but at
+  // least well-defined.
+  _hint_di = first_di();
+
+  post_initialize(&stream);
+
+  set_object_is_parsable(object_size);
+}
+
+// Get a measure of how much mileage the method has on it.
+int methodDataOopDesc::mileage_of(methodOop method) {
+  int mileage = 0;
+  int iic = method->interpreter_invocation_count();
+  if (mileage < iic)  mileage = iic;
+
+  InvocationCounter* ic = method->invocation_counter();
+  InvocationCounter* bc = method->backedge_counter();
+
+  int icval = ic->count();
+  if (ic->carry()) icval += CompileThreshold;
+  if (mileage < icval)  mileage = icval;
+  int bcval = bc->count();
+  if (bc->carry()) bcval += CompileThreshold;
+  if (mileage < bcval)  mileage = bcval;
+  return mileage;
+}
+
+bool methodDataOopDesc::is_mature() const {
+  uint current = mileage_of(_method);
+  uint initial = creation_mileage();
+  if (current < initial)
+    return true;  // some sort of overflow
+  uint target;
+  if (ProfileMaturityPercentage <= 0)
+    target = (uint) -ProfileMaturityPercentage;  // absolute value
+  else
+    target = (uint)( (ProfileMaturityPercentage * CompileThreshold) / 100 );
+  return (current >= initial + target);
+}
+
+// Translate a bci to its corresponding data index (di).
+address methodDataOopDesc::bci_to_dp(int bci) {
+  ResourceMark rm;
+  ProfileData* data = data_before(bci);
+  ProfileData* prev = NULL;
+  for ( ; is_valid(data); data = next_data(data)) {
+    if (data->bci() >= bci) {
+      if (data->bci() == bci)  set_hint_di(dp_to_di(data->dp()));
+      else if (prev != NULL)   set_hint_di(dp_to_di(prev->dp()));
+      return data->dp();
+    }
+    prev = data;
+  }
+  return (address)limit_data_position();
+}
+
+// Translate a bci to its corresponding data, or NULL.
+ProfileData* methodDataOopDesc::bci_to_data(int bci) {
+  ProfileData* data = data_before(bci);
+  for ( ; is_valid(data); data = next_data(data)) {
+    if (data->bci() == bci) {
+      set_hint_di(dp_to_di(data->dp()));
+      return data;
+    } else if (data->bci() > bci) {
+      break;
+    }
+  }
+  return bci_to_extra_data(bci, false);
+}
+
+// Translate a bci to its corresponding extra data, or NULL.
+ProfileData* methodDataOopDesc::bci_to_extra_data(int bci, bool create_if_missing) {
+  DataLayout* dp    = extra_data_base();
+  DataLayout* end   = extra_data_limit();
+  DataLayout* avail = NULL;
+  for (; dp < end; dp = next_extra(dp)) {
+    // No need for "OrderAccess::load_acquire" ops,
+    // since the data structure is monotonic.
+    if (dp->tag() == DataLayout::no_tag)  break;
+    if (dp->bci() == bci) {
+      assert(dp->tag() == DataLayout::bit_data_tag, "sane");
+      return new BitData(dp);
+    }
+  }
+  if (create_if_missing && dp < end) {
+    // Allocate this one.  There is no mutual exclusion,
+    // so two threads could allocate different BCIs to the
+    // same data layout.  This means these extra data
+    // records, like most other MDO contents, must not be
+    // trusted too much.
+    DataLayout temp;
+    temp.initialize(DataLayout::bit_data_tag, bci, 0);
+    dp->release_set_header(temp.header());
+    assert(dp->tag() == DataLayout::bit_data_tag, "sane");
+    //NO: assert(dp->bci() == bci, "no concurrent allocation");
+    return new BitData(dp);
+  }
+  return NULL;
+}
+
+#ifndef PRODUCT
+void methodDataOopDesc::print_data_on(outputStream* st) {
+  ResourceMark rm;
+  ProfileData* data = first_data();
+  for ( ; is_valid(data); data = next_data(data)) {
+    st->print("%d", dp_to_di(data->dp()));
+    st->fill_to(6);
+    data->print_data_on(st);
+  }
+  DataLayout* dp    = extra_data_base();
+  DataLayout* end   = extra_data_limit();
+  for (; dp < end; dp = next_extra(dp)) {
+    // No need for "OrderAccess::load_acquire" ops,
+    // since the data structure is monotonic.
+    if (dp->tag() == DataLayout::no_tag)  break;
+    if (dp == extra_data_base())
+      st->print_cr("--- Extra data:");
+    data = new BitData(dp);
+    st->print("%d", dp_to_di(data->dp()));
+    st->fill_to(6);
+    data->print_data_on(st);
+  }
+}
+#endif
+
+void methodDataOopDesc::verify_data_on(outputStream* st) {
+  NEEDS_CLEANUP;
+  // not yet implemented.
+}