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 /*

  * Copyright (c) 1998, 2014, 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.

  *

  */

 #include "precompiled.hpp"

 #include "ci/ciMethod.hpp"

 #include "ci/ciMethodBlocks.hpp"

 #include "ci/ciStreams.hpp"

 #include "compiler/methodLiveness.hpp"

 #include "interpreter/bytecode.hpp"

 #include "interpreter/bytecodes.hpp"

 #include "memory/allocation.inline.hpp"

 #include "utilities/bitMap.inline.hpp"

 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC

 // The MethodLiveness class performs a simple liveness analysis on a method

 // in order to decide which locals are live (that is, will be used again) at

 // a particular bytecode index (bci).

 //

 // The algorithm goes:

 //

 // 1. Break the method into a set of basic blocks.  For each basic block we

 //    also keep track of its set of predecessors through normal control flow

 //    and predecessors through exceptional control flow.

 //

 // 2. For each basic block, compute two sets, gen (the set of values used before

 //    they are defined) and kill (the set of values defined before they are used)

 //    in the basic block.  A basic block "needs" the locals in its gen set to

 //    perform its computation.  A basic block "provides" values for the locals in

 //    its kill set, allowing a need from a successor to be ignored.

 //

 // 3. Liveness information (the set of locals which are needed) is pushed backwards through

 //    the program, from blocks to their predecessors.  We compute and store liveness

 //    information for the normal/exceptional exit paths for each basic block.  When

 //    this process reaches a fixed point, we are done.

 //

 // 4. When we are asked about the liveness at a particular bci with a basic block, we

 //    compute gen/kill sets which represent execution from that bci to the exit of

 //    its blocks.  We then compose this range gen/kill information with the normal

 //    and exceptional exit information for the block to produce liveness information

 //    at that bci.

 //

 // The algorithm is approximate in many respects.  Notably:

 //

 // 1. We do not do the analysis necessary to match jsr's with the appropriate ret.

 //    Instead we make the conservative assumption that any ret can return to any

 //    jsr return site.

 // 2. Instead of computing the effects of exceptions at every instruction, we

 //    summarize the effects of all exceptional continuations from the block as

 //    a single set (_exception_exit), losing some information but simplifying the

 //    analysis.

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

 // The BitCounter class is used for counting the number of bits set in

 // some BitMap.  It is only used when collecting liveness statistics.

 #ifndef PRODUCT

 class BitCounter: public BitMapClosure {

  private:

   int _count;

  public:

   BitCounter() : _count(0) {}

   // Callback when bit in map is set

   virtual bool do_bit(size_t offset) {

     _count++;

     return true;

   }

   int count() {

     return _count;

   }

 };

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

 // Counts

 long MethodLiveness::_total_bytes = 0;

 int  MethodLiveness::_total_methods = 0;

 long MethodLiveness::_total_blocks = 0;

 int  MethodLiveness::_max_method_blocks = 0;

 long MethodLiveness::_total_edges = 0;

 int  MethodLiveness::_max_block_edges = 0;

 long MethodLiveness::_total_exc_edges = 0;

 int  MethodLiveness::_max_block_exc_edges = 0;

 long MethodLiveness::_total_method_locals = 0;

 int  MethodLiveness::_max_method_locals = 0;

 long MethodLiveness::_total_locals_queried = 0;

 long MethodLiveness::_total_live_locals_queried = 0;

 long MethodLiveness::_total_visits = 0;

 #endif

 // Timers

 elapsedTimer MethodLiveness::_time_build_graph;

 elapsedTimer MethodLiveness::_time_gen_kill;

 elapsedTimer MethodLiveness::_time_flow;

 elapsedTimer MethodLiveness::_time_query;

 elapsedTimer MethodLiveness::_time_total;

 MethodLiveness::MethodLiveness(Arena* arena, ciMethod* method)

 #ifdef COMPILER1

   : _bci_block_start((uintptr_t*)arena->Amalloc((method->code_size() >> LogBitsPerByte) + 1), method->code_size())

 #endif

 {

   _arena = arena;

   _method = method;

   _bit_map_size_bits = method->max_locals();

   _bit_map_size_words = (_bit_map_size_bits / sizeof(unsigned int)) + 1;

 #ifdef COMPILER1

   _bci_block_start.clear();

 #endif

 }

 void MethodLiveness::compute_liveness() {

 #ifndef PRODUCT

   if (TraceLivenessGen) {

     tty->print_cr("################################################################");

     tty->print("# Computing liveness information for ");

     method()->print_short_name();

   }

   if (TimeLivenessAnalysis) _time_total.start();

 #endif

   {

     TraceTime buildGraph(NULL, &_time_build_graph, TimeLivenessAnalysis);

     init_basic_blocks();

   }

   {

     TraceTime genKill(NULL, &_time_gen_kill, TimeLivenessAnalysis);

     init_gen_kill();

   }

   {

     TraceTime flow(NULL, &_time_flow, TimeLivenessAnalysis);

     propagate_liveness();

   }

 #ifndef PRODUCT

   if (TimeLivenessAnalysis) _time_total.stop();

   if (TimeLivenessAnalysis) {

     // Collect statistics

     _total_bytes += method()->code_size();

     _total_methods++;

     int num_blocks = _block_count;

     _total_blocks += num_blocks;

     _max_method_blocks = MAX2(num_blocks,_max_method_blocks);

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

       BasicBlock *block = _block_list[i];

       int numEdges = block->_normal_predecessors->length();

       int numExcEdges = block->_exception_predecessors->length();

       _total_edges += numEdges;

       _total_exc_edges += numExcEdges;

       _max_block_edges = MAX2(numEdges,_max_block_edges);

       _max_block_exc_edges = MAX2(numExcEdges,_max_block_exc_edges);

     }

     int numLocals = _bit_map_size_bits;

     _total_method_locals += numLocals;

     _max_method_locals = MAX2(numLocals,_max_method_locals);

   }

 #endif

 }

 void MethodLiveness::init_basic_blocks() {

   bool bailout = false;

   int method_len = method()->code_size();

   ciMethodBlocks *mblocks = method()->get_method_blocks();

   // Create an array to store the bci->BasicBlock mapping.

   _block_map = new (arena()) GrowableArray<BasicBlock*>(arena(), method_len, method_len, NULL);

   _block_count = mblocks->num_blocks();

   _block_list = (BasicBlock **) arena()->Amalloc(sizeof(BasicBlock *) * _block_count);

   // Used for patching up jsr/ret control flow.

   GrowableArray<BasicBlock*>* jsr_exit_list = new GrowableArray<BasicBlock*>(5);

   GrowableArray<BasicBlock*>* ret_list = new GrowableArray<BasicBlock*>(5);

   // generate our block list from ciMethodBlocks

   for (int blk = 0; blk < _block_count; blk++) {

     ciBlock *cib = mblocks->block(blk);

      int start_bci = cib->start_bci();

     _block_list[blk] = new (arena()) BasicBlock(this, start_bci, cib->limit_bci());

     _block_map->at_put(start_bci, _block_list[blk]);

 #ifdef COMPILER1

     // mark all bcis where a new basic block starts

     _bci_block_start.set_bit(start_bci);

 #endif // COMPILER1

   }

   // fill in the predecessors of blocks

   ciBytecodeStream bytes(method());

   for (int blk = 0; blk < _block_count; blk++) {

     BasicBlock *current_block = _block_list[blk];

     int bci =  mblocks->block(blk)->control_bci();

     if (bci == ciBlock::fall_through_bci) {

       int limit = current_block->limit_bci();

       if (limit < method_len) {

         BasicBlock *next = _block_map->at(limit);

         assert( next != NULL, "must be a block immediately following this one.");

         next->add_normal_predecessor(current_block);

       }

       continue;

     }

     bytes.reset_to_bci(bci);

     Bytecodes::Code code = bytes.next();

     BasicBlock *dest;

     // Now we need to interpret the instruction's effect

     // on control flow.

     assert (current_block != NULL, "we must have a current block");

     switch (code) {

       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:

         // Two way branch.  Set predecessors at each destination.

         dest = _block_map->at(bytes.next_bci());

         assert(dest != NULL, "must be a block immediately following this one.");

         dest->add_normal_predecessor(current_block);

         dest = _block_map->at(bytes.get_dest());

         assert(dest != NULL, "branch desination must start a block.");

         dest->add_normal_predecessor(current_block);

         break;

       case Bytecodes::_goto:

         dest = _block_map->at(bytes.get_dest());

         assert(dest != NULL, "branch desination must start a block.");

         dest->add_normal_predecessor(current_block);

         break;

       case Bytecodes::_goto_w:

         dest = _block_map->at(bytes.get_far_dest());

         assert(dest != NULL, "branch desination must start a block.");

         dest->add_normal_predecessor(current_block);

         break;

       case Bytecodes::_tableswitch:

         {

           Bytecode_tableswitch tableswitch(&bytes);

           int len = tableswitch.length();

           dest = _block_map->at(bci + tableswitch.default_offset());

           assert(dest != NULL, "branch desination must start a block.");

           dest->add_normal_predecessor(current_block);

           while (--len >= 0) {

             dest = _block_map->at(bci + tableswitch.dest_offset_at(len));

             assert(dest != NULL, "branch desination must start a block.");

             dest->add_normal_predecessor(current_block);

           }

           break;

         }

       case Bytecodes::_lookupswitch:

         {

           Bytecode_lookupswitch lookupswitch(&bytes);

           int npairs = lookupswitch.number_of_pairs();

           dest = _block_map->at(bci + lookupswitch.default_offset());

           assert(dest != NULL, "branch desination must start a block.");

           dest->add_normal_predecessor(current_block);

           while(--npairs >= 0) {

             LookupswitchPair pair = lookupswitch.pair_at(npairs);

             dest = _block_map->at( bci + pair.offset());

             assert(dest != NULL, "branch desination must start a block.");

             dest->add_normal_predecessor(current_block);

           }

           break;

         }

       case Bytecodes::_jsr:

         {

           assert(bytes.is_wide()==false, "sanity check");

           dest = _block_map->at(bytes.get_dest());

           assert(dest != NULL, "branch desination must start a block.");

           dest->add_normal_predecessor(current_block);

           BasicBlock *jsrExit = _block_map->at(current_block->limit_bci());

           assert(jsrExit != NULL, "jsr return bci must start a block.");

           jsr_exit_list->append(jsrExit);

           break;

         }

       case Bytecodes::_jsr_w:

         {

           dest = _block_map->at(bytes.get_far_dest());

           assert(dest != NULL, "branch desination must start a block.");

           dest->add_normal_predecessor(current_block);

           BasicBlock *jsrExit = _block_map->at(current_block->limit_bci());

           assert(jsrExit != NULL, "jsr return bci must start a block.");

           jsr_exit_list->append(jsrExit);

           break;

         }

       case Bytecodes::_wide:

         assert(false, "wide opcodes should not be seen here");

         break;

       case Bytecodes::_athrow:

       case Bytecodes::_ireturn:

       case Bytecodes::_lreturn:

       case Bytecodes::_freturn:

       case Bytecodes::_dreturn:

       case Bytecodes::_areturn:

       case Bytecodes::_return:

         // These opcodes are  not the normal predecessors of any other opcodes.

         break;

       case Bytecodes::_ret:

         // We will patch up jsr/rets in a subsequent pass.

         ret_list->append(current_block);

         break;

       case Bytecodes::_breakpoint:

         // Bail out of there are breakpoints in here.

         bailout = true;

         break;

       default:

         // Do nothing.

         break;

     }

   }

   // Patch up the jsr/ret's.  We conservatively assume that any ret

   // can return to any jsr site.

   int ret_list_len = ret_list->length();

   int jsr_exit_list_len = jsr_exit_list->length();

   if (ret_list_len > 0 && jsr_exit_list_len > 0) {

     for (int i = jsr_exit_list_len - 1; i >= 0; i--) {

       BasicBlock *jsrExit = jsr_exit_list->at(i);

       for (int i = ret_list_len - 1; i >= 0; i--) {

         jsrExit->add_normal_predecessor(ret_list->at(i));

       }

     }

   }

   // Compute exception edges.

   for (int b=_block_count-1; b >= 0; b--) {

     BasicBlock *block = _block_list[b];

     int block_start = block->start_bci();

     int block_limit = block->limit_bci();

     ciExceptionHandlerStream handlers(method());

     for (; !handlers.is_done(); handlers.next()) {

       ciExceptionHandler* handler = handlers.handler();

       int start       = handler->start();

       int limit       = handler->limit();

       int handler_bci = handler->handler_bci();

       int intersect_start = MAX2(block_start, start);

       int intersect_limit = MIN2(block_limit, limit);

       if (intersect_start < intersect_limit) {

         // The catch range has a nonempty intersection with this

         // basic block.  That means this basic block can be an

         // exceptional predecessor.

         _block_map->at(handler_bci)->add_exception_predecessor(block);

         if (handler->is_catch_all()) {

           // This is a catch-all block.

           if (intersect_start == block_start && intersect_limit == block_limit) {

             // The basic block is entirely contained in this catch-all block.

             // Skip the rest of the exception handlers -- they can never be

             // reached in execution.

             break;

           }

         }

       }

     }

   }

 }

 void MethodLiveness::init_gen_kill() {

   for (int i=_block_count-1; i >= 0; i--) {

     _block_list[i]->compute_gen_kill(method());

   }

 }

 void MethodLiveness::propagate_liveness() {

   int num_blocks = _block_count;

   BasicBlock *block;

   // We start our work list off with all blocks in it.

   // Alternately, we could start off the work list with the list of all

   // blocks which could exit the method directly, along with one block

   // from any infinite loop.  If this matters, it can be changed.  It

   // may not be clear from looking at the code, but the order of the

   // workList will be the opposite of the creation order of the basic

   // blocks, which should be decent for quick convergence (with the

   // possible exception of exception handlers, which are all created

   // early).

   _work_list = NULL;

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

     block = _block_list[i];

     block->set_next(_work_list);

     block->set_on_work_list(true);

     _work_list = block;

   }

   while ((block = work_list_get()) != NULL) {

     block->propagate(this);

     NOT_PRODUCT(_total_visits++;)

   }

 }

 void MethodLiveness::work_list_add(BasicBlock *block) {

   if (!block->on_work_list()) {

     block->set_next(_work_list);

     block->set_on_work_list(true);

     _work_list = block;

   }

 }

 MethodLiveness::BasicBlock *MethodLiveness::work_list_get() {

   BasicBlock *block = _work_list;

   if (block != NULL) {

     block->set_on_work_list(false);

     _work_list = block->next();

   }

   return block;

 }

 MethodLivenessResult MethodLiveness::get_liveness_at(int entry_bci) {

   int bci = entry_bci;

   bool is_entry = false;

   if (entry_bci == InvocationEntryBci) {

     is_entry = true;

     bci = 0;

   }

   MethodLivenessResult answer((uintptr_t*)NULL,0);

   if (_block_count > 0) {

     if (TimeLivenessAnalysis) _time_total.start();

     if (TimeLivenessAnalysis) _time_query.start();

     assert( 0 <= bci && bci < method()->code_size(), "bci out of range" );

     BasicBlock *block = _block_map->at(bci);

     // We may not be at the block start, so search backwards to find the block

     // containing bci.

     int t = bci;

     while (block == NULL && t > 0) {

      block = _block_map->at(--t);

     }

     assert( block != NULL, "invalid bytecode index; must be instruction index" );

     assert(bci >= block->start_bci() && bci < block->limit_bci(), "block must contain bci.");

     answer = block->get_liveness_at(method(), bci);

     if (is_entry && method()->is_synchronized() && !method()->is_static()) {

       // Synchronized methods use the receiver once on entry.

       answer.at_put(0, true);

     }

 #ifndef PRODUCT

     if (TraceLivenessQuery) {

       tty->print("Liveness query of ");

       method()->print_short_name();

       tty->print(" @ %d : result is ", bci);

       answer.print_on(tty);

     }

     if (TimeLivenessAnalysis) _time_query.stop();

     if (TimeLivenessAnalysis) _time_total.stop();

 #endif

   }

 #ifndef PRODUCT

   if (TimeLivenessAnalysis) {

     // Collect statistics.

     _total_locals_queried += _bit_map_size_bits;

     BitCounter counter;

     answer.iterate(&counter);

     _total_live_locals_queried += counter.count();

   }

 #endif

   return answer;

 }

 #ifndef PRODUCT

 void MethodLiveness::print_times() {

   tty->print_cr ("Accumulated liveness analysis times/statistics:");

   tty->print_cr ("-----------------------------------------------");

   tty->print_cr ("  Total         : %3.3f sec.", _time_total.seconds());

   tty->print_cr ("    Build graph : %3.3f sec. (%2.2f%%)", _time_build_graph.seconds(),

                  _time_build_graph.seconds() * 100 / _time_total.seconds());

   tty->print_cr ("    Gen / Kill  : %3.3f sec. (%2.2f%%)", _time_gen_kill.seconds(),

                  _time_gen_kill.seconds() * 100 / _time_total.seconds());

   tty->print_cr ("    Dataflow    : %3.3f sec. (%2.2f%%)", _time_flow.seconds(),

                  _time_flow.seconds() * 100 / _time_total.seconds());

   tty->print_cr ("    Query       : %3.3f sec. (%2.2f%%)", _time_query.seconds(),

                  _time_query.seconds() * 100 / _time_total.seconds());

   tty->print_cr ("  #bytes   : %8d (%3.0f bytes per sec)",

                  _total_bytes,

                  _total_bytes / _time_total.seconds());

   tty->print_cr ("  #methods : %8d (%3.0f methods per sec)",

                  _total_methods,

                  _total_methods / _time_total.seconds());

   tty->print_cr ("    avg locals : %3.3f    max locals : %3d",

                  (float)_total_method_locals / _total_methods,

                  _max_method_locals);

   tty->print_cr ("    avg blocks : %3.3f    max blocks : %3d",

                  (float)_total_blocks / _total_methods,

                  _max_method_blocks);

   tty->print_cr ("    avg bytes  : %3.3f",

                  (float)_total_bytes / _total_methods);

   tty->print_cr ("  #blocks  : %8d",

                  _total_blocks);

   tty->print_cr ("    avg normal predecessors    : %3.3f  max normal predecessors    : %3d",

                  (float)_total_edges / _total_blocks,

                  _max_block_edges);

   tty->print_cr ("    avg exception predecessors : %3.3f  max exception predecessors : %3d",

                  (float)_total_exc_edges / _total_blocks,

                  _max_block_exc_edges);

   tty->print_cr ("    avg visits                 : %3.3f",

                  (float)_total_visits / _total_blocks);

   tty->print_cr ("  #locals queried : %8d    #live : %8d   %%live : %2.2f%%",

                  _total_locals_queried,

                  _total_live_locals_queried,

                  100.0 * _total_live_locals_queried / _total_locals_queried);

 }

 #endif

 MethodLiveness::BasicBlock::BasicBlock(MethodLiveness *analyzer, int start, int limit) :

          _gen((uintptr_t*)analyzer->arena()->Amalloc(BytesPerWord * analyzer->bit_map_size_words()),

                          analyzer->bit_map_size_bits()),

          _kill((uintptr_t*)analyzer->arena()->Amalloc(BytesPerWord * analyzer->bit_map_size_words()),

                          analyzer->bit_map_size_bits()),

          _entry((uintptr_t*)analyzer->arena()->Amalloc(BytesPerWord * analyzer->bit_map_size_words()),

                          analyzer->bit_map_size_bits()),

          _normal_exit((uintptr_t*)analyzer->arena()->Amalloc(BytesPerWord * analyzer->bit_map_size_words()),

                          analyzer->bit_map_size_bits()),

          _exception_exit((uintptr_t*)analyzer->arena()->Amalloc(BytesPerWord * analyzer->bit_map_size_words()),

                          analyzer->bit_map_size_bits()),

          _last_bci(-1) {

   _analyzer = analyzer;

   _start_bci = start;

   _limit_bci = limit;

   _normal_predecessors =

     new (analyzer->arena()) GrowableArray<MethodLiveness::BasicBlock*>(analyzer->arena(), 5, 0, NULL);

   _exception_predecessors =

     new (analyzer->arena()) GrowableArray<MethodLiveness::BasicBlock*>(analyzer->arena(), 5, 0, NULL);

   _normal_exit.clear();

   _exception_exit.clear();

   _entry.clear();

   // this initialization is not strictly necessary.

   // _gen and _kill are cleared at the beginning of compute_gen_kill_range()

   _gen.clear();

   _kill.clear();

 }

 MethodLiveness::BasicBlock *MethodLiveness::BasicBlock::split(int split_bci) {

   int start = _start_bci;

   int limit = _limit_bci;

   if (TraceLivenessGen) {

     tty->print_cr(" ** Splitting block (%d,%d) at %d", start, limit, split_bci);

   }

   GrowableArray<BasicBlock*>* save_predecessors = _normal_predecessors;

   assert (start < split_bci && split_bci < limit, "improper split");

   // Make a new block to cover the first half of the range.

   BasicBlock *first_half = new (_analyzer->arena()) BasicBlock(_analyzer, start, split_bci);

   // Assign correct values to the second half (this)

   _normal_predecessors = first_half->_normal_predecessors;

   _start_bci = split_bci;

   add_normal_predecessor(first_half);

   // Assign correct predecessors to the new first half

   first_half->_normal_predecessors = save_predecessors;

   return first_half;

 }

 void MethodLiveness::BasicBlock::compute_gen_kill(ciMethod* method) {

   ciBytecodeStream bytes(method);

   bytes.reset_to_bci(start_bci());

   bytes.set_max_bci(limit_bci());

   compute_gen_kill_range(&bytes);

 }

 void MethodLiveness::BasicBlock::compute_gen_kill_range(ciBytecodeStream *bytes) {

   _gen.clear();

   _kill.clear();

   while (bytes->next() != ciBytecodeStream::EOBC()) {

     compute_gen_kill_single(bytes);

   }

 }

 void MethodLiveness::BasicBlock::compute_gen_kill_single(ciBytecodeStream *instruction) {

   int localNum;

   // We prohibit _gen and _kill from having locals in common.  If we

   // know that one is definitely going to be applied before the other,

   // we could save some computation time by relaxing this prohibition.

   switch (instruction->cur_bc()) {

     case Bytecodes::_nop:

     case Bytecodes::_goto:

     case Bytecodes::_goto_w:

     case Bytecodes::_aconst_null:

     case Bytecodes::_new:

     case Bytecodes::_iconst_m1:

     case Bytecodes::_iconst_0:

     case Bytecodes::_iconst_1:

     case Bytecodes::_iconst_2:

     case Bytecodes::_iconst_3:

     case Bytecodes::_iconst_4:

     case Bytecodes::_iconst_5:

     case Bytecodes::_fconst_0:

     case Bytecodes::_fconst_1:

     case Bytecodes::_fconst_2:

     case Bytecodes::_bipush:

     case Bytecodes::_sipush:

     case Bytecodes::_lconst_0:

     case Bytecodes::_lconst_1:

     case Bytecodes::_dconst_0:

     case Bytecodes::_dconst_1:

     case Bytecodes::_ldc2_w:

     case Bytecodes::_ldc:

     case Bytecodes::_ldc_w:

     case Bytecodes::_iaload:

     case Bytecodes::_faload:

     case Bytecodes::_baload:

     case Bytecodes::_caload:

     case Bytecodes::_saload:

     case Bytecodes::_laload:

     case Bytecodes::_daload:

     case Bytecodes::_aaload:

     case Bytecodes::_iastore:

     case Bytecodes::_fastore:

     case Bytecodes::_bastore:

     case Bytecodes::_castore:

     case Bytecodes::_sastore:

     case Bytecodes::_lastore:

     case Bytecodes::_dastore:

     case Bytecodes::_aastore:

     case Bytecodes::_pop:

     case Bytecodes::_pop2:

     case Bytecodes::_dup:

     case Bytecodes::_dup_x1:

     case Bytecodes::_dup_x2:

     case Bytecodes::_dup2:

     case Bytecodes::_dup2_x1:

     case Bytecodes::_dup2_x2:

     case Bytecodes::_swap:

     case Bytecodes::_iadd:

     case Bytecodes::_fadd:

     case Bytecodes::_isub:

     case Bytecodes::_fsub:

     case Bytecodes::_imul:

     case Bytecodes::_fmul:

     case Bytecodes::_idiv:

     case Bytecodes::_fdiv:

     case Bytecodes::_irem:

     case Bytecodes::_frem:

     case Bytecodes::_ishl:

     case Bytecodes::_ishr:

     case Bytecodes::_iushr:

     case Bytecodes::_iand:

     case Bytecodes::_ior:

     case Bytecodes::_ixor:

     case Bytecodes::_l2f:

     case Bytecodes::_l2i:

     case Bytecodes::_d2f:

     case Bytecodes::_d2i:

     case Bytecodes::_fcmpl:

     case Bytecodes::_fcmpg:

     case Bytecodes::_ladd:

     case Bytecodes::_dadd:

     case Bytecodes::_lsub:

     case Bytecodes::_dsub:

     case Bytecodes::_lmul:

     case Bytecodes::_dmul:

     case Bytecodes::_ldiv:

     case Bytecodes::_ddiv:

     case Bytecodes::_lrem:

     case Bytecodes::_drem:

     case Bytecodes::_land:

     case Bytecodes::_lor:

     case Bytecodes::_lxor:

     case Bytecodes::_ineg:

     case Bytecodes::_fneg:

     case Bytecodes::_i2f:

     case Bytecodes::_f2i:

     case Bytecodes::_i2c:

     case Bytecodes::_i2s:

     case Bytecodes::_i2b:

     case Bytecodes::_lneg:

     case Bytecodes::_dneg:

     case Bytecodes::_l2d:

     case Bytecodes::_d2l:

     case Bytecodes::_lshl:

     case Bytecodes::_lshr:

     case Bytecodes::_lushr:

     case Bytecodes::_i2l:

     case Bytecodes::_i2d:

     case Bytecodes::_f2l:

     case Bytecodes::_f2d:

     case Bytecodes::_lcmp:

     case Bytecodes::_dcmpl:

     case Bytecodes::_dcmpg:

     case Bytecodes::_ifeq:

     case Bytecodes::_ifne:

     case Bytecodes::_iflt:

     case Bytecodes::_ifge:

     case Bytecodes::_ifgt:

     case Bytecodes::_ifle:

     case Bytecodes::_tableswitch:

     case Bytecodes::_ireturn:

     case Bytecodes::_freturn:

     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::_lreturn:

     case Bytecodes::_dreturn:

     case Bytecodes::_if_acmpeq:

     case Bytecodes::_if_acmpne:

     case Bytecodes::_jsr:

     case Bytecodes::_jsr_w:

     case Bytecodes::_getstatic:

     case Bytecodes::_putstatic:

     case Bytecodes::_getfield:

     case Bytecodes::_putfield:

     case Bytecodes::_invokevirtual:

     case Bytecodes::_invokespecial:

     case Bytecodes::_invokestatic:

     case Bytecodes::_invokeinterface:

     case Bytecodes::_invokedynamic:

     case Bytecodes::_newarray:

     case Bytecodes::_anewarray:

     case Bytecodes::_checkcast:

     case Bytecodes::_arraylength:

     case Bytecodes::_instanceof:

     case Bytecodes::_athrow:

     case Bytecodes::_areturn:

     case Bytecodes::_monitorenter:

     case Bytecodes::_monitorexit:

     case Bytecodes::_ifnull:

     case Bytecodes::_ifnonnull:

     case Bytecodes::_multianewarray:

     case Bytecodes::_lookupswitch:

       // These bytecodes have no effect on the method's locals.

       break;

     case Bytecodes::_return:

       if (instruction->method()->intrinsic_id() == vmIntrinsics::_Object_init) {

         // return from Object.init implicitly registers a finalizer

         // for the receiver if needed, so keep it alive.

         load_one(0);

       }

       break;

     case Bytecodes::_lload:

     case Bytecodes::_dload:

       load_two(instruction->get_index());

       break;

     case Bytecodes::_lload_0:

     case Bytecodes::_dload_0:

       load_two(0);

       break;

     case Bytecodes::_lload_1:

     case Bytecodes::_dload_1:

       load_two(1);

       break;

     case Bytecodes::_lload_2:

     case Bytecodes::_dload_2:

       load_two(2);

       break;

     case Bytecodes::_lload_3:

     case Bytecodes::_dload_3:

       load_two(3);

       break;

     case Bytecodes::_iload:

     case Bytecodes::_iinc:

     case Bytecodes::_fload:

     case Bytecodes::_aload:

     case Bytecodes::_ret:

       load_one(instruction->get_index());

       break;

     case Bytecodes::_iload_0:

     case Bytecodes::_fload_0:

     case Bytecodes::_aload_0:

       load_one(0);

       break;

     case Bytecodes::_iload_1:

     case Bytecodes::_fload_1:

     case Bytecodes::_aload_1:

       load_one(1);

       break;

     case Bytecodes::_iload_2:

     case Bytecodes::_fload_2:

     case Bytecodes::_aload_2:

       load_one(2);

       break;

     case Bytecodes::_iload_3:

     case Bytecodes::_fload_3:

     case Bytecodes::_aload_3:

       load_one(3);

       break;

     case Bytecodes::_lstore:

     case Bytecodes::_dstore:

       store_two(localNum = instruction->get_index());

       break;

     case Bytecodes::_lstore_0:

     case Bytecodes::_dstore_0:

       store_two(0);

       break;

     case Bytecodes::_lstore_1:

     case Bytecodes::_dstore_1:

       store_two(1);

       break;

     case Bytecodes::_lstore_2:

     case Bytecodes::_dstore_2:

       store_two(2);

       break;

     case Bytecodes::_lstore_3:

     case Bytecodes::_dstore_3:

       store_two(3);

       break;

     case Bytecodes::_istore:

     case Bytecodes::_fstore:

     case Bytecodes::_astore:

       store_one(instruction->get_index());

       break;

     case Bytecodes::_istore_0:

     case Bytecodes::_fstore_0:

     case Bytecodes::_astore_0:

       store_one(0);

       break;

     case Bytecodes::_istore_1:

     case Bytecodes::_fstore_1:

     case Bytecodes::_astore_1:

       store_one(1);

       break;

     case Bytecodes::_istore_2:

     case Bytecodes::_fstore_2:

     case Bytecodes::_astore_2:

       store_one(2);

       break;

     case Bytecodes::_istore_3:

     case Bytecodes::_fstore_3:

     case Bytecodes::_astore_3:

       store_one(3);

       break;

     case Bytecodes::_wide:

       fatal("Iterator should skip this bytecode");

       break;

     default:

       tty->print("unexpected opcode: %d\n", instruction->cur_bc());

       ShouldNotReachHere();

       break;

   }

 }

 void MethodLiveness::BasicBlock::load_two(int local) {

   load_one(local);

   load_one(local+1);

 }

 void MethodLiveness::BasicBlock::load_one(int local) {

   if (!_kill.at(local)) {

     _gen.at_put(local, true);

   }

 }

 void MethodLiveness::BasicBlock::store_two(int local) {

   store_one(local);

   store_one(local+1);

 }

 void MethodLiveness::BasicBlock::store_one(int local) {

   if (!_gen.at(local)) {

     _kill.at_put(local, true);

   }

 }

 void MethodLiveness::BasicBlock::propagate(MethodLiveness *ml) {

   // These set operations could be combined for efficiency if the

   // performance of this analysis becomes an issue.

   _entry.set_union(_normal_exit);

   _entry.set_difference(_kill);

   _entry.set_union(_gen);

   // Note that we merge information from our exceptional successors

   // just once, rather than at individual bytecodes.

   _entry.set_union(_exception_exit);

   if (TraceLivenessGen) {

     tty->print_cr(" ** Visiting block at %d **", start_bci());

     print_on(tty);

   }

   int i;

   for (i=_normal_predecessors->length()-1; i>=0; i--) {

     BasicBlock *block = _normal_predecessors->at(i);

     if (block->merge_normal(_entry)) {

       ml->work_list_add(block);

     }

   }

   for (i=_exception_predecessors->length()-1; i>=0; i--) {

     BasicBlock *block = _exception_predecessors->at(i);

     if (block->merge_exception(_entry)) {

       ml->work_list_add(block);

     }

   }

 }

 bool MethodLiveness::BasicBlock::merge_normal(BitMap other) {

   return _normal_exit.set_union_with_result(other);

 }

 bool MethodLiveness::BasicBlock::merge_exception(BitMap other) {

   return _exception_exit.set_union_with_result(other);

 }

 MethodLivenessResult MethodLiveness::BasicBlock::get_liveness_at(ciMethod* method, int bci) {

   MethodLivenessResult answer(NEW_RESOURCE_ARRAY(uintptr_t, _analyzer->bit_map_size_words()),

                 _analyzer->bit_map_size_bits());

   answer.set_is_valid();

 #ifndef ASSERT

   if (bci == start_bci()) {

     answer.set_from(_entry);

     return answer;

   }

 #endif

 #ifdef ASSERT

   ResourceMark rm;

   BitMap g(_gen.size()); g.set_from(_gen);

   BitMap k(_kill.size()); k.set_from(_kill);

 #endif

   if (_last_bci != bci || trueInDebug) {

     ciBytecodeStream bytes(method);

     bytes.reset_to_bci(bci);

     bytes.set_max_bci(limit_bci());

     compute_gen_kill_range(&bytes);

     assert(_last_bci != bci ||

            (g.is_same(_gen) && k.is_same(_kill)), "cached computation is incorrect");

     _last_bci = bci;

   }

   answer.clear();

   answer.set_union(_normal_exit);

   answer.set_difference(_kill);

   answer.set_union(_gen);

   answer.set_union(_exception_exit);

 #ifdef ASSERT

   if (bci == start_bci()) {

     assert(answer.is_same(_entry), "optimized answer must be accurate");

   }

 #endif

   return answer;

 }

 #ifndef PRODUCT

 void MethodLiveness::BasicBlock::print_on(outputStream *os) const {

   os->print_cr("===================================================================");

   os->print_cr("    Block start: %4d, limit: %4d", _start_bci, _limit_bci);

   os->print   ("    Normal predecessors (%2d)      @", _normal_predecessors->length());

   int i;

   for (i=0; i < _normal_predecessors->length(); i++) {

     os->print(" %4d", _normal_predecessors->at(i)->start_bci());

   }

   os->cr();

   os->print   ("    Exceptional predecessors (%2d) @", _exception_predecessors->length());

   for (i=0; i < _exception_predecessors->length(); i++) {

     os->print(" %4d", _exception_predecessors->at(i)->start_bci());

   }

   os->cr();

   os->print ("    Normal Exit   : ");

   _normal_exit.print_on(os);

   os->print ("    Gen           : ");

   _gen.print_on(os);

   os->print ("    Kill          : ");

   _kill.print_on(os);

   os->print ("    Exception Exit: ");

   _exception_exit.print_on(os);

   os->print ("    Entry         : ");

   _entry.print_on(os);

 }

 #endif // PRODUCT