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

 /*

  * Copyright 2000-2009 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.

  *

  */

 class BytecodeStream;

 // The MethodData object collects counts and other profile information

 // during zeroth-tier (interpretive) and first-tier execution.

 // The profile is used later by compilation heuristics.  Some heuristics

 // enable use of aggressive (or "heroic") optimizations.  An aggressive

 // optimization often has a down-side, a corner case that it handles

 // poorly, but which is thought to be rare.  The profile provides

 // evidence of this rarity for a given method or even BCI.  It allows

 // the compiler to back out of the optimization at places where it

 // has historically been a poor choice.  Other heuristics try to use

 // specific information gathered about types observed at a given site.

 //

 // All data in the profile is approximate.  It is expected to be accurate

 // on the whole, but the system expects occasional inaccuraces, due to

 // counter overflow, multiprocessor races during data collection, space

 // limitations, missing MDO blocks, etc.  Bad or missing data will degrade

 // optimization quality but will not affect correctness.  Also, each MDO

 // is marked with its birth-date ("creation_mileage") which can be used

 // to assess the quality ("maturity") of its data.

 //

 // Short (<32-bit) counters are designed to overflow to a known "saturated"

 // state.  Also, certain recorded per-BCI events are given one-bit counters

 // which overflow to a saturated state which applied to all counters at

 // that BCI.  In other words, there is a small lattice which approximates

 // the ideal of an infinite-precision counter for each event at each BCI,

 // and the lattice quickly "bottoms out" in a state where all counters

 // are taken to be indefinitely large.

 //

 // The reader will find many data races in profile gathering code, starting

 // with invocation counter incrementation.  None of these races harm correct

 // execution of the compiled code.

 // forward decl

 class ProfileData;

 // DataLayout

 //

 // Overlay for generic profiling data.

 class DataLayout VALUE_OBJ_CLASS_SPEC {

 private:

   // Every data layout begins with a header.  This header

   // contains a tag, which is used to indicate the size/layout

   // of the data, 4 bits of flags, which can be used in any way,

   // 4 bits of trap history (none/one reason/many reasons),

   // and a bci, which is used to tie this piece of data to a

   // specific bci in the bytecodes.

   union {

     intptr_t _bits;

     struct {

       u1 _tag;

       u1 _flags;

       u2 _bci;

     } _struct;

   } _header;

   // The data layout has an arbitrary number of cells, each sized

   // to accomodate a pointer or an integer.

   intptr_t _cells[1];

   // Some types of data layouts need a length field.

   static bool needs_array_len(u1 tag);

 public:

   enum {

     counter_increment = 1

   };

   enum {

     cell_size = sizeof(intptr_t)

   };

   // Tag values

   enum {

     no_tag,

     bit_data_tag,

     counter_data_tag,

     jump_data_tag,

     receiver_type_data_tag,

     virtual_call_data_tag,

     ret_data_tag,

     branch_data_tag,

     multi_branch_data_tag,

     arg_info_data_tag

   };

   enum {

     // The _struct._flags word is formatted as [trap_state:4 | flags:4].

     // The trap state breaks down further as [recompile:1 | reason:3].

     // This further breakdown is defined in deoptimization.cpp.

     // See Deoptimization::trap_state_reason for an assert that

     // trap_bits is big enough to hold reasons < Reason_RECORDED_LIMIT.

     //

     // The trap_state is collected only if ProfileTraps is true.

     trap_bits = 1+3,  // 3: enough to distinguish [0..Reason_RECORDED_LIMIT].

     trap_shift = BitsPerByte - trap_bits,

     trap_mask = right_n_bits(trap_bits),

     trap_mask_in_place = (trap_mask << trap_shift),

     flag_limit = trap_shift,

     flag_mask = right_n_bits(flag_limit),

     first_flag = 0

   };

   // Size computation

   static int header_size_in_bytes() {

     return cell_size;

   }

   static int header_size_in_cells() {

     return 1;

   }

   static int compute_size_in_bytes(int cell_count) {

     return header_size_in_bytes() + cell_count * cell_size;

   }

   // Initialization

   void initialize(u1 tag, u2 bci, int cell_count);

   // Accessors

   u1 tag() {

     return _header._struct._tag;

   }

   // Return a few bits of trap state.  Range is [0..trap_mask].

   // The state tells if traps with zero, one, or many reasons have occurred.

   // It also tells whether zero or many recompilations have occurred.

   // The associated trap histogram in the MDO itself tells whether

   // traps are common or not.  If a BCI shows that a trap X has

   // occurred, and the MDO shows N occurrences of X, we make the

   // simplifying assumption that all N occurrences can be blamed

   // on that BCI.

   int trap_state() {

     return ((_header._struct._flags >> trap_shift) & trap_mask);

   }

   void set_trap_state(int new_state) {

     assert(ProfileTraps, "used only under +ProfileTraps");

     uint old_flags = (_header._struct._flags & flag_mask);

     _header._struct._flags = (new_state << trap_shift) | old_flags;

   }

   u1 flags() {

     return _header._struct._flags;

   }

   u2 bci() {

     return _header._struct._bci;

   }

   void set_header(intptr_t value) {

     _header._bits = value;

   }

   void release_set_header(intptr_t value) {

     OrderAccess::release_store_ptr(&_header._bits, value);

   }

   intptr_t header() {

     return _header._bits;

   }

   void set_cell_at(int index, intptr_t value) {

     _cells[index] = value;

   }

   void release_set_cell_at(int index, intptr_t value) {

     OrderAccess::release_store_ptr(&_cells[index], value);

   }

   intptr_t cell_at(int index) {

     return _cells[index];

   }

   intptr_t* adr_cell_at(int index) {

     return &_cells[index];

   }

   oop* adr_oop_at(int index) {

     return (oop*)&(_cells[index]);

   }

   void set_flag_at(int flag_number) {

     assert(flag_number < flag_limit, "oob");

     _header._struct._flags |= (0x1 << flag_number);

   }

   bool flag_at(int flag_number) {

     assert(flag_number < flag_limit, "oob");

     return (_header._struct._flags & (0x1 << flag_number)) != 0;

   }

   // Low-level support for code generation.

   static ByteSize header_offset() {

     return byte_offset_of(DataLayout, _header);

   }

   static ByteSize tag_offset() {

     return byte_offset_of(DataLayout, _header._struct._tag);

   }

   static ByteSize flags_offset() {

     return byte_offset_of(DataLayout, _header._struct._flags);

   }

   static ByteSize bci_offset() {

     return byte_offset_of(DataLayout, _header._struct._bci);

   }

   static ByteSize cell_offset(int index) {

     return byte_offset_of(DataLayout, _cells[index]);

   }

   // Return a value which, when or-ed as a byte into _flags, sets the flag.

   static int flag_number_to_byte_constant(int flag_number) {

     assert(0 <= flag_number && flag_number < flag_limit, "oob");

     DataLayout temp; temp.set_header(0);

     temp.set_flag_at(flag_number);

     return temp._header._struct._flags;

   }

   // Return a value which, when or-ed as a word into _header, sets the flag.

   static intptr_t flag_mask_to_header_mask(int byte_constant) {

     DataLayout temp; temp.set_header(0);

     temp._header._struct._flags = byte_constant;

     return temp._header._bits;

   }

   // GC support

   ProfileData* data_in();

   void follow_weak_refs(BoolObjectClosure* cl);

 };

 // ProfileData class hierarchy

 class ProfileData;

 class   BitData;

 class     CounterData;

 class       ReceiverTypeData;

 class         VirtualCallData;

 class       RetData;

 class   JumpData;

 class     BranchData;

 class   ArrayData;

 class     MultiBranchData;

 class     ArgInfoData;

 // ProfileData

 //

 // A ProfileData object is created to refer to a section of profiling

 // data in a structured way.

 class ProfileData : public ResourceObj {

 private:

 #ifndef PRODUCT

   enum {

     tab_width_one = 16,

     tab_width_two = 36

   };

 #endif // !PRODUCT

   // This is a pointer to a section of profiling data.

   DataLayout* _data;

 protected:

   DataLayout* data() { return _data; }

   enum {

     cell_size = DataLayout::cell_size

   };

 public:

   // How many cells are in this?

   virtual int cell_count() {

     ShouldNotReachHere();

     return -1;

   }

   // Return the size of this data.

   int size_in_bytes() {

     return DataLayout::compute_size_in_bytes(cell_count());

   }

 protected:

   // Low-level accessors for underlying data

   void set_intptr_at(int index, intptr_t value) {

     assert(0 <= index && index < cell_count(), "oob");

     data()->set_cell_at(index, value);

   }

   void release_set_intptr_at(int index, intptr_t value) {

     assert(0 <= index && index < cell_count(), "oob");

     data()->release_set_cell_at(index, value);

   }

   intptr_t intptr_at(int index) {

     assert(0 <= index && index < cell_count(), "oob");

     return data()->cell_at(index);

   }

   void set_uint_at(int index, uint value) {

     set_intptr_at(index, (intptr_t) value);

   }

   void release_set_uint_at(int index, uint value) {

     release_set_intptr_at(index, (intptr_t) value);

   }

   uint uint_at(int index) {

     return (uint)intptr_at(index);

   }

   void set_int_at(int index, int value) {

     set_intptr_at(index, (intptr_t) value);

   }

   void release_set_int_at(int index, int value) {

     release_set_intptr_at(index, (intptr_t) value);

   }

   int int_at(int index) {

     return (int)intptr_at(index);

   }

   int int_at_unchecked(int index) {

     return (int)data()->cell_at(index);

   }

   void set_oop_at(int index, oop value) {

     set_intptr_at(index, (intptr_t) value);

   }

   oop oop_at(int index) {

     return (oop)intptr_at(index);

   }

   oop* adr_oop_at(int index) {

     assert(0 <= index && index < cell_count(), "oob");

     return data()->adr_oop_at(index);

   }

   void set_flag_at(int flag_number) {

     data()->set_flag_at(flag_number);

   }

   bool flag_at(int flag_number) {

     return data()->flag_at(flag_number);

   }

   // two convenient imports for use by subclasses:

   static ByteSize cell_offset(int index) {

     return DataLayout::cell_offset(index);

   }

   static int flag_number_to_byte_constant(int flag_number) {

     return DataLayout::flag_number_to_byte_constant(flag_number);

   }

   ProfileData(DataLayout* data) {

     _data = data;

   }

 public:

   // Constructor for invalid ProfileData.

   ProfileData();

   u2 bci() {

     return data()->bci();

   }

   address dp() {

     return (address)_data;

   }

   int trap_state() {

     return data()->trap_state();

   }

   void set_trap_state(int new_state) {

     data()->set_trap_state(new_state);

   }

   // Type checking

   virtual bool is_BitData()         { return false; }

   virtual bool is_CounterData()     { return false; }

   virtual bool is_JumpData()        { return false; }

   virtual bool is_ReceiverTypeData(){ return false; }

   virtual bool is_VirtualCallData() { return false; }

   virtual bool is_RetData()         { return false; }

   virtual bool is_BranchData()      { return false; }

   virtual bool is_ArrayData()       { return false; }

   virtual bool is_MultiBranchData() { return false; }

   virtual bool is_ArgInfoData()     { return false; }

   BitData* as_BitData() {

     assert(is_BitData(), "wrong type");

     return is_BitData()         ? (BitData*)        this : NULL;

   }

   CounterData* as_CounterData() {

     assert(is_CounterData(), "wrong type");

     return is_CounterData()     ? (CounterData*)    this : NULL;

   }

   JumpData* as_JumpData() {

     assert(is_JumpData(), "wrong type");

     return is_JumpData()        ? (JumpData*)       this : NULL;

   }

   ReceiverTypeData* as_ReceiverTypeData() {

     assert(is_ReceiverTypeData(), "wrong type");

     return is_ReceiverTypeData() ? (ReceiverTypeData*)this : NULL;

   }

   VirtualCallData* as_VirtualCallData() {

     assert(is_VirtualCallData(), "wrong type");

     return is_VirtualCallData() ? (VirtualCallData*)this : NULL;

   }

   RetData* as_RetData() {

     assert(is_RetData(), "wrong type");

     return is_RetData()         ? (RetData*)        this : NULL;

   }

   BranchData* as_BranchData() {

     assert(is_BranchData(), "wrong type");

     return is_BranchData()      ? (BranchData*)     this : NULL;

   }

   ArrayData* as_ArrayData() {

     assert(is_ArrayData(), "wrong type");

     return is_ArrayData()       ? (ArrayData*)      this : NULL;

   }

   MultiBranchData* as_MultiBranchData() {

     assert(is_MultiBranchData(), "wrong type");

     return is_MultiBranchData() ? (MultiBranchData*)this : NULL;

   }

   ArgInfoData* as_ArgInfoData() {

     assert(is_ArgInfoData(), "wrong type");

     return is_ArgInfoData() ? (ArgInfoData*)this : NULL;

   }

   // Subclass specific initialization

   virtual void post_initialize(BytecodeStream* stream, methodDataOop mdo) {}

   // GC support

   virtual void follow_contents() {}

   virtual void oop_iterate(OopClosure* blk) {}

   virtual void oop_iterate_m(OopClosure* blk, MemRegion mr) {}

   virtual void adjust_pointers() {}

   virtual void follow_weak_refs(BoolObjectClosure* is_alive_closure) {}

 #ifndef SERIALGC

   // Parallel old support

   virtual void follow_contents(ParCompactionManager* cm) {}

   virtual void update_pointers() {}

   virtual void update_pointers(HeapWord* beg_addr, HeapWord* end_addr) {}

 #endif // SERIALGC

   // CI translation: ProfileData can represent both MethodDataOop data

   // as well as CIMethodData data. This function is provided for translating

   // an oop in a ProfileData to the ci equivalent. Generally speaking,

   // most ProfileData don't require any translation, so we provide the null

   // translation here, and the required translators are in the ci subclasses.

   virtual void translate_from(ProfileData* data) {}

   virtual void print_data_on(outputStream* st) {

     ShouldNotReachHere();

   }

 #ifndef PRODUCT

   void print_shared(outputStream* st, const char* name);

   void tab(outputStream* st);

 #endif

 };

 // BitData

 //

 // A BitData holds a flag or two in its header.

 class BitData : public ProfileData {

 protected:

   enum {

     // null_seen:

     //  saw a null operand (cast/aastore/instanceof)

     null_seen_flag              = DataLayout::first_flag + 0

   };

   enum { bit_cell_count = 0 };  // no additional data fields needed.

 public:

   BitData(DataLayout* layout) : ProfileData(layout) {

   }

   virtual bool is_BitData() { return true; }

   static int static_cell_count() {

     return bit_cell_count;

   }

   virtual int cell_count() {

     return static_cell_count();

   }

   // Accessor

   // The null_seen flag bit is specially known to the interpreter.

   // Consulting it allows the compiler to avoid setting up null_check traps.

   bool null_seen()     { return flag_at(null_seen_flag); }

   void set_null_seen()    { set_flag_at(null_seen_flag); }

   // Code generation support

   static int null_seen_byte_constant() {

     return flag_number_to_byte_constant(null_seen_flag);

   }

   static ByteSize bit_data_size() {

     return cell_offset(bit_cell_count);

   }

 #ifndef PRODUCT

   void print_data_on(outputStream* st);

 #endif

 };

 // CounterData

 //

 // A CounterData corresponds to a simple counter.

 class CounterData : public BitData {

 protected:

   enum {

     count_off,

     counter_cell_count

   };

 public:

   CounterData(DataLayout* layout) : BitData(layout) {}

   virtual bool is_CounterData() { return true; }

   static int static_cell_count() {

     return counter_cell_count;

   }

   virtual int cell_count() {

     return static_cell_count();

   }

   // Direct accessor

   uint count() {

     return uint_at(count_off);

   }

   // Code generation support

   static ByteSize count_offset() {

     return cell_offset(count_off);

   }

   static ByteSize counter_data_size() {

     return cell_offset(counter_cell_count);

   }

 #ifndef PRODUCT

   void print_data_on(outputStream* st);

 #endif

 };

 // 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.

 class JumpData : public ProfileData {

 protected:

   enum {

     taken_off_set,

     displacement_off_set,

     jump_cell_count

   };

   void set_displacement(int displacement) {

     set_int_at(displacement_off_set, displacement);

   }

 public:

   JumpData(DataLayout* layout) : ProfileData(layout) {

     assert(layout->tag() == DataLayout::jump_data_tag ||

       layout->tag() == DataLayout::branch_data_tag, "wrong type");

   }

   virtual bool is_JumpData() { return true; }

   static int static_cell_count() {

     return jump_cell_count;

   }

   virtual int cell_count() {

     return static_cell_count();

   }

   // Direct accessor

   uint taken() {

     return uint_at(taken_off_set);

   }

   // Saturating counter

   uint inc_taken() {

     uint cnt = taken() + 1;

     // Did we wrap? Will compiler screw us??

     if (cnt == 0) cnt--;

     set_uint_at(taken_off_set, cnt);

     return cnt;

   }

   int displacement() {

     return int_at(displacement_off_set);

   }

   // Code generation support

   static ByteSize taken_offset() {

     return cell_offset(taken_off_set);

   }

   static ByteSize displacement_offset() {

     return cell_offset(displacement_off_set);

   }

   // Specific initialization.

   void post_initialize(BytecodeStream* stream, methodDataOop mdo);

 #ifndef PRODUCT

   void print_data_on(outputStream* st);

 #endif

 };

 // 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.

 class ReceiverTypeData : public CounterData {

 protected:

   enum {

     receiver0_offset = counter_cell_count,

     count0_offset,

     receiver_type_row_cell_count = (count0_offset + 1) - receiver0_offset

   };

 public:

   ReceiverTypeData(DataLayout* layout) : CounterData(layout) {

     assert(layout->tag() == DataLayout::receiver_type_data_tag ||

            layout->tag() == DataLayout::virtual_call_data_tag, "wrong type");

   }

   virtual bool is_ReceiverTypeData() { return true; }

   static int static_cell_count() {

     return counter_cell_count + (uint) TypeProfileWidth * receiver_type_row_cell_count;

   }

   virtual int cell_count() {

     return static_cell_count();

   }

   // Direct accessors

   static uint row_limit() {

     return TypeProfileWidth;

   }

   static int receiver_cell_index(uint row) {

     return receiver0_offset + row * receiver_type_row_cell_count;

   }

   static int receiver_count_cell_index(uint row) {

     return count0_offset + row * receiver_type_row_cell_count;

   }

   // Get the receiver at row.  The 'unchecked' version is needed by parallel old

   // gc; it does not assert the receiver is a klass.  During compaction of the

   // perm gen, the klass may already have moved, so the is_klass() predicate

   // would fail.  The 'normal' version should be used whenever possible.

   klassOop receiver_unchecked(uint row) {

     assert(row < row_limit(), "oob");

     oop recv = oop_at(receiver_cell_index(row));

     return (klassOop)recv;

   }

   klassOop receiver(uint row) {

     klassOop recv = receiver_unchecked(row);

     assert(recv == NULL || ((oop)recv)->is_klass(), "wrong type");

     return recv;

   }

   void set_receiver(uint row, oop p) {

     assert((uint)row < row_limit(), "oob");

     set_oop_at(receiver_cell_index(row), p);

   }

   uint receiver_count(uint row) {

     assert(row < row_limit(), "oob");

     return uint_at(receiver_count_cell_index(row));

   }

   void set_receiver_count(uint row, uint count) {

     assert(row < row_limit(), "oob");

     set_uint_at(receiver_count_cell_index(row), count);

   }

   void clear_row(uint row) {

     assert(row < row_limit(), "oob");

     set_receiver(row, NULL);

     set_receiver_count(row, 0);

   }

   // Code generation support

   static ByteSize receiver_offset(uint row) {

     return cell_offset(receiver_cell_index(row));

   }

   static ByteSize receiver_count_offset(uint row) {

     return cell_offset(receiver_count_cell_index(row));

   }

   static ByteSize receiver_type_data_size() {

     return cell_offset(static_cell_count());

   }

   // GC support

   virtual void follow_contents();

   virtual void oop_iterate(OopClosure* blk);

   virtual void oop_iterate_m(OopClosure* blk, MemRegion mr);

   virtual void adjust_pointers();

   virtual void follow_weak_refs(BoolObjectClosure* is_alive_closure);

 #ifndef SERIALGC

   // Parallel old support

   virtual void follow_contents(ParCompactionManager* cm);

   virtual void update_pointers();

   virtual void update_pointers(HeapWord* beg_addr, HeapWord* end_addr);

 #endif // SERIALGC

   oop* adr_receiver(uint row) {

     return adr_oop_at(receiver_cell_index(row));

   }

 #ifndef PRODUCT

   void print_receiver_data_on(outputStream* st);

   void print_data_on(outputStream* st);

 #endif

 };

 // VirtualCallData

 //

 // A VirtualCallData is used to access profiling information about a

 // virtual call.  For now, it has nothing more than a ReceiverTypeData.

 class VirtualCallData : public ReceiverTypeData {

 public:

   VirtualCallData(DataLayout* layout) : ReceiverTypeData(layout) {

     assert(layout->tag() == DataLayout::virtual_call_data_tag, "wrong type");

   }

   virtual bool is_VirtualCallData() { return true; }

   static int static_cell_count() {

     // At this point we could add more profile state, e.g., for arguments.

     // But for now it's the same size as the base record type.

     return ReceiverTypeData::static_cell_count();

   }

   virtual int cell_count() {

     return static_cell_count();

   }

   // Direct accessors

   static ByteSize virtual_call_data_size() {

     return cell_offset(static_cell_count());

   }

 #ifndef PRODUCT

   void print_data_on(outputStream* st);

 #endif

 };

 // 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 data displacement.

 class RetData : public CounterData {

 protected:

   enum {

     bci0_offset = counter_cell_count,

     count0_offset,

     displacement0_offset,

     ret_row_cell_count = (displacement0_offset + 1) - bci0_offset

   };

   void set_bci(uint row, int bci) {

     assert((uint)row < row_limit(), "oob");

     set_int_at(bci0_offset + row * ret_row_cell_count, bci);

   }

   void release_set_bci(uint row, int bci) {

     assert((uint)row < row_limit(), "oob");

     // 'release' when setting the bci acts as a valid flag for other

     // threads wrt bci_count and bci_displacement.

     release_set_int_at(bci0_offset + row * ret_row_cell_count, bci);

   }

   void set_bci_count(uint row, uint count) {

     assert((uint)row < row_limit(), "oob");

     set_uint_at(count0_offset + row * ret_row_cell_count, count);

   }

   void set_bci_displacement(uint row, int disp) {

     set_int_at(displacement0_offset + row * ret_row_cell_count, disp);

   }

 public:

   RetData(DataLayout* layout) : CounterData(layout) {

     assert(layout->tag() == DataLayout::ret_data_tag, "wrong type");

   }

   virtual bool is_RetData() { return true; }

   enum {

     no_bci = -1 // value of bci when bci1/2 are not in use.

   };

   static int static_cell_count() {

     return counter_cell_count + (uint) BciProfileWidth * ret_row_cell_count;

   }

   virtual int cell_count() {

     return static_cell_count();

   }

   static uint row_limit() {

     return BciProfileWidth;

   }

   static int bci_cell_index(uint row) {

     return bci0_offset + row * ret_row_cell_count;

   }

   static int bci_count_cell_index(uint row) {

     return count0_offset + row * ret_row_cell_count;

   }

   static int bci_displacement_cell_index(uint row) {

     return displacement0_offset + row * ret_row_cell_count;

   }

   // Direct accessors

   int bci(uint row) {

     return int_at(bci_cell_index(row));

   }

   uint bci_count(uint row) {

     return uint_at(bci_count_cell_index(row));

   }

   int bci_displacement(uint row) {

     return int_at(bci_displacement_cell_index(row));

   }

   // Interpreter Runtime support

   address fixup_ret(int return_bci, methodDataHandle mdo);

   // Code generation support

   static ByteSize bci_offset(uint row) {

     return cell_offset(bci_cell_index(row));

   }

   static ByteSize bci_count_offset(uint row) {

     return cell_offset(bci_count_cell_index(row));

   }

   static ByteSize bci_displacement_offset(uint row) {

     return cell_offset(bci_displacement_cell_index(row));

   }

   // Specific initialization.

   void post_initialize(BytecodeStream* stream, methodDataOop mdo);

 #ifndef PRODUCT

   void print_data_on(outputStream* st);

 #endif

 };

 // 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.

 class BranchData : public JumpData {

 protected:

   enum {

     not_taken_off_set = jump_cell_count,

     branch_cell_count

   };

   void set_displacement(int displacement) {

     set_int_at(displacement_off_set, displacement);

   }

 public:

   BranchData(DataLayout* layout) : JumpData(layout) {

     assert(layout->tag() == DataLayout::branch_data_tag, "wrong type");

   }

   virtual bool is_BranchData() { return true; }

   static int static_cell_count() {

     return branch_cell_count;

   }

   virtual int cell_count() {

     return static_cell_count();

   }

   // Direct accessor

   uint not_taken() {

     return uint_at(not_taken_off_set);

   }

   uint inc_not_taken() {

     uint cnt = not_taken() + 1;

     // Did we wrap? Will compiler screw us??

     if (cnt == 0) cnt--;

     set_uint_at(not_taken_off_set, cnt);

     return cnt;

   }

   // Code generation support

   static ByteSize not_taken_offset() {

     return cell_offset(not_taken_off_set);

   }

   static ByteSize branch_data_size() {

     return cell_offset(branch_cell_count);

   }

   // Specific initialization.

   void post_initialize(BytecodeStream* stream, methodDataOop mdo);

 #ifndef PRODUCT

   void print_data_on(outputStream* st);

 #endif

 };

 // ArrayData

 //

 // A ArrayData is a base class for accessing profiling data which does

 // not have a statically known size.  It consists of an array length

 // and an array start.

 class ArrayData : public ProfileData {

 protected:

   friend class DataLayout;

   enum {

     array_len_off_set,

     array_start_off_set

   };

   uint array_uint_at(int index) {

     int aindex = index + array_start_off_set;

     return uint_at(aindex);

   }

   int array_int_at(int index) {

     int aindex = index + array_start_off_set;

     return int_at(aindex);

   }

   oop array_oop_at(int index) {

     int aindex = index + array_start_off_set;

     return oop_at(aindex);

   }

   void array_set_int_at(int index, int value) {

     int aindex = index + array_start_off_set;

     set_int_at(aindex, value);

   }

   // Code generation support for subclasses.

   static ByteSize array_element_offset(int index) {

     return cell_offset(array_start_off_set + index);

   }

 public:

   ArrayData(DataLayout* layout) : ProfileData(layout) {}

   virtual bool is_ArrayData() { return true; }

   static int static_cell_count() {

     return -1;

   }

   int array_len() {

     return int_at_unchecked(array_len_off_set);

   }

   virtual int cell_count() {

     return array_len() + 1;

   }

   // Code generation support

   static ByteSize array_len_offset() {

     return cell_offset(array_len_off_set);

   }

   static ByteSize array_start_offset() {

     return cell_offset(array_start_off_set);

   }

 };

 // 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.

 class MultiBranchData : public ArrayData {

 protected:

   enum {

     default_count_off_set,

     default_disaplacement_off_set,

     case_array_start

   };

   enum {

     relative_count_off_set,

     relative_displacement_off_set,

     per_case_cell_count

   };

   void set_default_displacement(int displacement) {

     array_set_int_at(default_disaplacement_off_set, displacement);

   }

   void set_displacement_at(int index, int displacement) {

     array_set_int_at(case_array_start +

                      index * per_case_cell_count +

                      relative_displacement_off_set,

                      displacement);

   }

 public:

   MultiBranchData(DataLayout* layout) : ArrayData(layout) {

     assert(layout->tag() == DataLayout::multi_branch_data_tag, "wrong type");

   }

   virtual bool is_MultiBranchData() { return true; }

   static int compute_cell_count(BytecodeStream* stream);

   int number_of_cases() {

     int alen = array_len() - 2; // get rid of default case here.

     assert(alen % per_case_cell_count == 0, "must be even");

     return (alen / per_case_cell_count);

   }

   uint default_count() {

     return array_uint_at(default_count_off_set);

   }

   int default_displacement() {

     return array_int_at(default_disaplacement_off_set);

   }

   uint count_at(int index) {

     return array_uint_at(case_array_start +

                          index * per_case_cell_count +

                          relative_count_off_set);

   }

   int displacement_at(int index) {

     return array_int_at(case_array_start +

                         index * per_case_cell_count +

                         relative_displacement_off_set);

   }

   // Code generation support

   static ByteSize default_count_offset() {

     return array_element_offset(default_count_off_set);

   }

   static ByteSize default_displacement_offset() {

     return array_element_offset(default_disaplacement_off_set);

   }

   static ByteSize case_count_offset(int index) {

     return case_array_offset() +

            (per_case_size() * index) +

            relative_count_offset();

   }

   static ByteSize case_array_offset() {

     return array_element_offset(case_array_start);

   }

   static ByteSize per_case_size() {

     return in_ByteSize(per_case_cell_count) * cell_size;

   }

   static ByteSize relative_count_offset() {

     return in_ByteSize(relative_count_off_set) * cell_size;

   }

   static ByteSize relative_displacement_offset() {

     return in_ByteSize(relative_displacement_off_set) * cell_size;

   }

   // Specific initialization.

   void post_initialize(BytecodeStream* stream, methodDataOop mdo);

 #ifndef PRODUCT

   void print_data_on(outputStream* st);

 #endif

 };

 class ArgInfoData : public ArrayData {

 public:

   ArgInfoData(DataLayout* layout) : ArrayData(layout) {

     assert(layout->tag() == DataLayout::arg_info_data_tag, "wrong type");

   }

   virtual bool is_ArgInfoData() { return true; }

   int number_of_args() {

     return array_len();

   }

   uint arg_modified(int arg) {

     return array_uint_at(arg);

   }

   void set_arg_modified(int arg, uint val) {

     array_set_int_at(arg, val);

   }

 #ifndef PRODUCT

   void print_data_on(outputStream* st);

 #endif

 };

 // methodDataOop

 //

 // A methodDataOop holds information which has been collected about

 // a method.  Its layout looks like this:

 //

 // -----------------------------

 // | header                    |

 // | klass                     |

 // -----------------------------

 // | method                    |

 // | size of the methodDataOop |

 // -----------------------------

 // | Data entries...           |

 // |   (variable size)         |

 // |                           |

 // .                           .

 // .                           .

 // .                           .

 // |                           |

 // -----------------------------

 //

 // The data entry area is a heterogeneous array of DataLayouts. Each

 // DataLayout in the array corresponds to a specific bytecode in the

 // method.  The entries in the array are sorted by the corresponding

 // bytecode.  Access to the data is via resource-allocated ProfileData,

 // which point to the underlying blocks of DataLayout structures.

 //

 // During interpretation, if profiling in enabled, the interpreter

 // maintains a method data pointer (mdp), which points at the entry

 // in the array corresponding to the current bci.  In the course of

 // intepretation, when a bytecode is encountered that has profile data

 // associated with it, the entry pointed to by mdp is updated, then the

 // mdp is adjusted to point to the next appropriate DataLayout.  If mdp

 // is NULL to begin with, the interpreter assumes that the current method

 // is not (yet) being profiled.

 //

 // In methodDataOop parlance, "dp" is a "data pointer", the actual address

 // of a DataLayout element.  A "di" is a "data index", the offset in bytes

 // from the base of the data entry array.  A "displacement" is the byte offset

 // in certain ProfileData objects that indicate the amount the mdp must be

 // adjusted in the event of a change in control flow.

 //

 class methodDataOopDesc : public oopDesc {

   friend class VMStructs;

 private:

   friend class ProfileData;

   // Back pointer to the methodOop

   methodOop _method;

   // Size of this oop in bytes

   int _size;

   // Cached hint for bci_to_dp and bci_to_data

   int _hint_di;

   // Whole-method sticky bits and flags

 public:

   enum {

     _trap_hist_limit    = 16,   // decoupled from Deoptimization::Reason_LIMIT

     _trap_hist_mask     = max_jubyte,

     _extra_data_count   = 4     // extra DataLayout headers, for trap history

   }; // Public flag values

 private:

   uint _nof_decompiles;             // count of all nmethod removals

   uint _nof_overflow_recompiles;    // recompile count, excluding recomp. bits

   uint _nof_overflow_traps;         // trap count, excluding _trap_hist

   union {

     intptr_t _align;

     u1 _array[_trap_hist_limit];

   } _trap_hist;

   // Support for interprocedural escape analysis, from Thomas Kotzmann.

   intx              _eflags;          // flags on escape information

   intx              _arg_local;       // bit set of non-escaping arguments

   intx              _arg_stack;       // bit set of stack-allocatable arguments

   intx              _arg_returned;    // bit set of returned arguments

   int _creation_mileage;            // method mileage at MDO creation

   // Size of _data array in bytes.  (Excludes header and extra_data fields.)

   int _data_size;

   // Beginning of the data entries

   intptr_t _data[1];

   // Helper for size computation

   static int compute_data_size(BytecodeStream* stream);

   static int bytecode_cell_count(Bytecodes::Code code);

   enum { no_profile_data = -1, variable_cell_count = -2 };

   // Helper for initialization

   DataLayout* data_layout_at(int data_index) {

     assert(data_index % sizeof(intptr_t) == 0, "unaligned");

     return (DataLayout*) (((address)_data) + data_index);

   }

   // Initialize an individual data segment.  Returns the size of

   // the segment in bytes.

   int initialize_data(BytecodeStream* stream, int data_index);

   // Helper for data_at

   DataLayout* limit_data_position() {

     return (DataLayout*)((address)data_base() + _data_size);

   }

   bool out_of_bounds(int data_index) {

     return data_index >= data_size();

   }

   // Give each of the data entries a chance to perform specific

   // data initialization.

   void post_initialize(BytecodeStream* stream);

   // hint accessors

   int      hint_di() const  { return _hint_di; }

   void set_hint_di(int di)  {

     assert(!out_of_bounds(di), "hint_di out of bounds");

     _hint_di = di;

   }

   ProfileData* data_before(int bci) {

     // avoid SEGV on this edge case

     if (data_size() == 0)

       return NULL;

     int hint = hint_di();

     if (data_layout_at(hint)->bci() <= bci)

       return data_at(hint);

     return first_data();

   }

   // What is the index of the first data entry?

   int first_di() { return 0; }

   // Find or create an extra ProfileData:

   ProfileData* bci_to_extra_data(int bci, bool create_if_missing);

   // return the argument info cell

   ArgInfoData *arg_info();

 public:

   static int header_size() {

     return sizeof(methodDataOopDesc)/wordSize;

   }

   // Compute the size of a methodDataOop before it is created.

   static int compute_allocation_size_in_bytes(methodHandle method);

   static int compute_allocation_size_in_words(methodHandle method);

   static int compute_extra_data_count(int data_size, int empty_bc_count);

   // Determine if a given bytecode can have profile information.

   static bool bytecode_has_profile(Bytecodes::Code code) {

     return bytecode_cell_count(code) != no_profile_data;

   }

   // Perform initialization of a new methodDataOop

   void initialize(methodHandle method);

   // My size

   int object_size_in_bytes() { return _size; }

   int object_size() {

     return align_object_size(align_size_up(_size, BytesPerWord)/BytesPerWord);

   }

   int      creation_mileage() const  { return _creation_mileage; }

   void set_creation_mileage(int x)   { _creation_mileage = x; }

   bool is_mature() const;  // consult mileage and ProfileMaturityPercentage

   static int mileage_of(methodOop m);

   // Support for interprocedural escape analysis, from Thomas Kotzmann.

   enum EscapeFlag {

     estimated    = 1 << 0,

     return_local = 1 << 1,

     return_allocated = 1 << 2,

     allocated_escapes = 1 << 3,

     unknown_modified = 1 << 4

   };

   intx eflags()                                  { return _eflags; }

   intx arg_local()                               { return _arg_local; }

   intx arg_stack()                               { return _arg_stack; }

   intx arg_returned()                            { return _arg_returned; }

   uint arg_modified(int a)                       { ArgInfoData *aid = arg_info();

                                                    assert(a >= 0 && a < aid->number_of_args(), "valid argument number");

                                                    return aid->arg_modified(a); }

   void set_eflags(intx v)                        { _eflags = v; }

   void set_arg_local(intx v)                     { _arg_local = v; }

   void set_arg_stack(intx v)                     { _arg_stack = v; }

   void set_arg_returned(intx v)                  { _arg_returned = v; }

   void set_arg_modified(int a, uint v)           { ArgInfoData *aid = arg_info();

                                                    assert(a >= 0 && a < aid->number_of_args(), "valid argument number");

                                                    aid->set_arg_modified(a, v); }

   void clear_escape_info()                       { _eflags = _arg_local = _arg_stack = _arg_returned = 0; }

   // Location and size of data area

   address data_base() const {

     return (address) _data;

   }

   int data_size() {

     return _data_size;

   }

   // Accessors

   methodOop method() { return _method; }

   // Get the data at an arbitrary (sort of) data index.

   ProfileData* data_at(int data_index);

   // Walk through the data in order.

   ProfileData* first_data() { return data_at(first_di()); }

   ProfileData* next_data(ProfileData* current);

   bool is_valid(ProfileData* current) { return current != NULL; }

   // Convert a dp (data pointer) to a di (data index).

   int dp_to_di(address dp) {

     return dp - ((address)_data);

   }

   address di_to_dp(int di) {

     return (address)data_layout_at(di);

   }

   // bci to di/dp conversion.

   address bci_to_dp(int bci);

   int bci_to_di(int bci) {

     return dp_to_di(bci_to_dp(bci));

   }

   // Get the data at an arbitrary bci, or NULL if there is none.

   ProfileData* bci_to_data(int bci);

   // Same, but try to create an extra_data record if one is needed:

   ProfileData* allocate_bci_to_data(int bci) {

     ProfileData* data = bci_to_data(bci);

     return (data != NULL) ? data : bci_to_extra_data(bci, true);

   }

   // Add a handful of extra data records, for trap tracking.

   DataLayout* extra_data_base() { return limit_data_position(); }

   DataLayout* extra_data_limit() { return (DataLayout*)((address)this + object_size_in_bytes()); }

   int extra_data_size() { return (address)extra_data_limit()

                                - (address)extra_data_base(); }

   static DataLayout* next_extra(DataLayout* dp) { return (DataLayout*)((address)dp + in_bytes(DataLayout::cell_offset(0))); }

   // Return (uint)-1 for overflow.

   uint trap_count(int reason) const {

     assert((uint)reason < _trap_hist_limit, "oob");

     return (int)((_trap_hist._array[reason]+1) & _trap_hist_mask) - 1;

   }

   // For loops:

   static uint trap_reason_limit() { return _trap_hist_limit; }

   static uint trap_count_limit()  { return _trap_hist_mask; }

   uint inc_trap_count(int reason) {

     // Count another trap, anywhere in this method.

     assert(reason >= 0, "must be single trap");

     if ((uint)reason < _trap_hist_limit) {

       uint cnt1 = 1 + _trap_hist._array[reason];

       if ((cnt1 & _trap_hist_mask) != 0) {  // if no counter overflow...

         _trap_hist._array[reason] = cnt1;

         return cnt1;

       } else {

         return _trap_hist_mask + (++_nof_overflow_traps);

       }

     } else {

       // Could not represent the count in the histogram.

       return (++_nof_overflow_traps);

     }

   }

   uint overflow_trap_count() const {

     return _nof_overflow_traps;

   }

   uint overflow_recompile_count() const {

     return _nof_overflow_recompiles;

   }

   void inc_overflow_recompile_count() {

     _nof_overflow_recompiles += 1;

   }

   uint decompile_count() const {

     return _nof_decompiles;

   }

   void inc_decompile_count() {

     _nof_decompiles += 1;

   }

   // Support for code generation

   static ByteSize data_offset() {

     return byte_offset_of(methodDataOopDesc, _data[0]);

   }

   // GC support

   oop* adr_method() const { return (oop*)&_method; }

   bool object_is_parsable() const { return _size != 0; }

   void set_object_is_parsable(int object_size_in_bytes) { _size = object_size_in_bytes; }

 #ifndef PRODUCT

   // printing support for method data

   void print_data_on(outputStream* st);

 #endif

   // verification

   void verify_data_on(outputStream* st);

 };