Mercurial > jdk8-mips64-public > hotspot / file revision

 /*

  * Copyright (c) 2000, 2011, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

  * or visit www.oracle.com if you need additional information or have any

  * questions.

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  */

 #include "precompiled.hpp"

 #include "classfile/systemDictionary.hpp"

 #include "gc_implementation/shared/markSweep.inline.hpp"

 #include "interpreter/bytecode.hpp"

 #include "interpreter/bytecodeStream.hpp"

 #include "interpreter/linkResolver.hpp"

 #include "oops/methodDataOop.hpp"

 #include "oops/oop.inline.hpp"

 #include "runtime/compilationPolicy.hpp"

 #include "runtime/deoptimization.hpp"

 #include "runtime/handles.inline.hpp"

 // ==================================================================

 // 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) || (tag == arg_info_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.

   }

 }

 void DataLayout::follow_weak_refs(BoolObjectClosure* cl) {

   ResourceMark m;

   data_in()->follow_weak_refs(cl);

 }

 // ==================================================================

 // 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() {

   // This is a set of weak references that need

   // to be followed at the end of the strong marking

   // phase. Memoize this object so it can be visited

   // in the weak roots processing phase.

   MarkSweep::revisit_mdo(data());

 }

 #ifndef SERIALGC

 void ReceiverTypeData::follow_contents(ParCompactionManager* cm) {

   // This is a set of weak references that need

   // to be followed at the end of the strong marking

   // phase. Memoize this object so it can be visited

   // in the weak roots processing phase.

   PSParallelCompact::revisit_mdo(cm, data());

 }

 #endif // SERIALGC

 void ReceiverTypeData::oop_iterate(OopClosure* blk) {

   if (blk->should_remember_mdo()) {

     // This is a set of weak references that need

     // to be followed at the end of the strong marking

     // phase. Memoize this object so it can be visited

     // in the weak roots processing phase.

     blk->remember_mdo(data());

   } else { // normal scan

     for (uint row = 0; row < row_limit(); row++) {

       if (receiver(row) != NULL) {

         oop* adr = adr_receiver(row);

         blk->do_oop(adr);

       }

     }

   }

 }

 void ReceiverTypeData::oop_iterate_m(OopClosure* blk, MemRegion mr) {

   // Currently, this interface is called only during card-scanning for

   // a young gen gc, in which case this object cannot contribute anything,

   // since it does not contain any references that cross out of

   // the perm gen. However, for future more general use we allow

   // the possibility of calling for instance from more general

   // iterators (for example, a future regionalized perm gen for G1,

   // or the possibility of moving some references out of perm in

   // the case of other collectors). In that case, you will need

   // to relax or remove some of the assertions below.

 #ifdef ASSERT

   // Verify that none of the embedded oop references cross out of

   // this generation.

   for (uint row = 0; row < row_limit(); row++) {

     if (receiver(row) != NULL) {

       oop* adr = adr_receiver(row);

       CollectedHeap* h = Universe::heap();

       assert(h->is_permanent(adr) && h->is_permanent_or_null(*adr), "Not intra-perm");

     }

   }

 #endif // ASSERT

   assert(!blk->should_remember_mdo(), "Not expected to remember MDO");

   return;   // Nothing to do, see comment above

 #if 0

   if (blk->should_remember_mdo()) {

     // This is a set of weak references that need

     // to be followed at the end of the strong marking

     // phase. Memoize this object so it can be visited

     // in the weak roots processing phase.

     blk->remember_mdo(data());

   } else { // normal scan

     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);

         } else if ((HeapWord*)adr >= mr.end()) {

           // Test that the current cursor and the two ends of the range

           // that we may have skipped iterating over are monotonically ordered;

           // this is just a paranoid assertion, just in case represetations

           // should change in the future rendering the short-circuit return

           // here invalid.

           assert((row+1 >= row_limit() || adr_receiver(row+1) > adr) &&

                  (row+2 >= row_limit() || adr_receiver(row_limit()-1) > adr_receiver(row+1)), "Reducing?");

           break; // remaining should be outside this mr too

         }

       }

     }

   }

 #endif

 }

 void ReceiverTypeData::adjust_pointers() {

   for (uint row = 0; row < row_limit(); row++) {

     if (receiver(row) != NULL) {

       MarkSweep::adjust_pointer(adr_receiver(row));

     }

   }

 }

 void ReceiverTypeData::follow_weak_refs(BoolObjectClosure* is_alive_cl) {

   for (uint row = 0; row < row_limit(); row++) {

     klassOop p = receiver(row);

     if (p != NULL && !is_alive_cl->do_object_b(p)) {

       clear_row(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));

     }

   }

 }

 #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);

   int total = count();

   for (row = 0; row < row_limit(); row++) {

     if (receiver(row) != NULL) {

       total += receiver_count(row);

     }

   }

   for (row = 0; row < row_limit(); row++) {

     if (receiver(row) != NULL) {

       tab(st);

       receiver(row)->print_value_on(st);

       st->print_cr("(%u %4.2f)", receiver_count(row), (float) receiver_count(row) / (float) total);

     }

   }

 }

 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(stream->method()(), stream->bcp());

     cell_count = 1 + per_case_cell_count * (1 + sw.length()); // 1 for default

   } else {

     Bytecode_lookupswitch sw(stream->method()(), 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(stream->method()(), 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(stream->method()(), 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

 #ifndef PRODUCT

 void ArgInfoData::print_data_on(outputStream* st) {

   print_shared(st, "ArgInfoData");

   int nargs = number_of_args();

   for (int i = 0; i < nargs; i++) {

     st->print("  0x%x", arg_modified(i));

   }

   st->cr();

 }

 #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::_invokedynamic:

     return CounterData::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);

   // Add a cell to record information about modified arguments.

   int arg_size = method->size_of_parameters();

   object_size += DataLayout::compute_size_in_bytes(arg_size+1);

   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::_invokedynamic:

     // %%% should make a type profile for any invokedynamic that takes a ref argument

     cell_count = CounterData::static_cell_count();

     tag = DataLayout::counter_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);

   return data_layout->data_in();

 }

 ProfileData* DataLayout::data_in() {

   switch (tag()) {

   case DataLayout::no_tag:

   default:

     ShouldNotReachHere();

     return NULL;

   case DataLayout::bit_data_tag:

     return new BitData(this);

   case DataLayout::counter_data_tag:

     return new CounterData(this);

   case DataLayout::jump_data_tag:

     return new JumpData(this);

   case DataLayout::receiver_type_data_tag:

     return new ReceiverTypeData(this);

   case DataLayout::virtual_call_data_tag:

     return new VirtualCallData(this);

   case DataLayout::ret_data_tag:

     return new RetData(this);

   case DataLayout::branch_data_tag:

     return new BranchData(this);

   case DataLayout::multi_branch_data_tag:

     return new MultiBranchData(this);

   case DataLayout::arg_info_data_tag:

     return new ArgInfoData(this);

   };

 }

 // 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();

   if (TieredCompilation) {

     _invocation_counter.init();

     _backedge_counter.init();

     _invocation_counter_start = 0;

     _backedge_counter_start = 0;

     _num_loops = 0;

     _num_blocks = 0;

     _highest_comp_level = 0;

     _highest_osr_comp_level = 0;

     _would_profile = true;

   }

   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);

   int extra_size = extra_data_count * DataLayout::compute_size_in_bytes(0);

   // Add a cell to record information about modified arguments.

   // Set up _args_modified array after traps cells so that

   // the code for traps cells works.

   DataLayout *dp = data_layout_at(data_size + extra_size);

   int arg_size = method->size_of_parameters();

   dp->initialize(DataLayout::arg_info_data_tag, 0, arg_size+1);

   object_size += extra_size + DataLayout::compute_size_in_bytes(arg_size+1);

   // 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;

   if (TieredCompilation) {

     mileage = MAX2(method->invocation_count(), method->backedge_count());

   } else {

     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 {

   return CompilationPolicy::policy()->is_mature(_method);

 }

 // 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->tag() == DataLayout::arg_info_data_tag) {

       dp = end; // ArgInfoData is at the end of extra data section.

       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;

 }

 ArgInfoData *methodDataOopDesc::arg_info() {

   DataLayout* dp    = extra_data_base();

   DataLayout* end   = extra_data_limit();

   for (; dp < end; dp = next_extra(dp)) {

     if (dp->tag() == DataLayout::arg_info_data_tag)

       return new ArgInfoData(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);

   }

   st->print_cr("--- Extra data:");

   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)  continue;

     if (dp->tag() == DataLayout::bit_data_tag) {

       data = new BitData(dp);

     } else {

       assert(dp->tag() == DataLayout::arg_info_data_tag, "must be BitData or ArgInfo");

       data = new ArgInfoData(dp);

       dp = end; // ArgInfoData is at the end of extra data section.

     }

     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.

 }