src/share/vm/c1/c1_IR.cpp

Fri, 03 Sep 2010 17:51:07 -0700

author
iveresov
date
Fri, 03 Sep 2010 17:51:07 -0700
changeset 2138
d5d065957597
parent 1939
b812ff5abc73
child 2174
f02a8bbe6ed4
permissions
-rw-r--r--

6953144: Tiered compilation
Summary: Infrastructure for tiered compilation support (interpreter + c1 + c2) for 32 and 64 bit. Simple tiered policy implementation.
Reviewed-by: kvn, never, phh, twisti

     1 /*
     2  * Copyright (c) 1999, 2010, Oracle and/or its affiliates. All rights reserved.
     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
     4  *
     5  * This code is free software; you can redistribute it and/or modify it
     6  * under the terms of the GNU General Public License version 2 only, as
     7  * published by the Free Software Foundation.
     8  *
     9  * This code is distributed in the hope that it will be useful, but WITHOUT
    10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
    11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
    12  * version 2 for more details (a copy is included in the LICENSE file that
    13  * accompanied this code).
    14  *
    15  * You should have received a copy of the GNU General Public License version
    16  * 2 along with this work; if not, write to the Free Software Foundation,
    17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
    18  *
    19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
    20  * or visit www.oracle.com if you need additional information or have any
    21  * questions.
    22  *
    23  */
    25 # include "incls/_precompiled.incl"
    26 # include "incls/_c1_IR.cpp.incl"
    29 // Implementation of XHandlers
    30 //
    31 // Note: This code could eventually go away if we are
    32 //       just using the ciExceptionHandlerStream.
    34 XHandlers::XHandlers(ciMethod* method) : _list(method->exception_table_length()) {
    35   ciExceptionHandlerStream s(method);
    36   while (!s.is_done()) {
    37     _list.append(new XHandler(s.handler()));
    38     s.next();
    39   }
    40   assert(s.count() == method->exception_table_length(), "exception table lengths inconsistent");
    41 }
    43 // deep copy of all XHandler contained in list
    44 XHandlers::XHandlers(XHandlers* other) :
    45   _list(other->length())
    46 {
    47   for (int i = 0; i < other->length(); i++) {
    48     _list.append(new XHandler(other->handler_at(i)));
    49   }
    50 }
    52 // Returns whether a particular exception type can be caught.  Also
    53 // returns true if klass is unloaded or any exception handler
    54 // classes are unloaded.  type_is_exact indicates whether the throw
    55 // is known to be exactly that class or it might throw a subtype.
    56 bool XHandlers::could_catch(ciInstanceKlass* klass, bool type_is_exact) const {
    57   // the type is unknown so be conservative
    58   if (!klass->is_loaded()) {
    59     return true;
    60   }
    62   for (int i = 0; i < length(); i++) {
    63     XHandler* handler = handler_at(i);
    64     if (handler->is_catch_all()) {
    65       // catch of ANY
    66       return true;
    67     }
    68     ciInstanceKlass* handler_klass = handler->catch_klass();
    69     // if it's unknown it might be catchable
    70     if (!handler_klass->is_loaded()) {
    71       return true;
    72     }
    73     // if the throw type is definitely a subtype of the catch type
    74     // then it can be caught.
    75     if (klass->is_subtype_of(handler_klass)) {
    76       return true;
    77     }
    78     if (!type_is_exact) {
    79       // If the type isn't exactly known then it can also be caught by
    80       // catch statements where the inexact type is a subtype of the
    81       // catch type.
    82       // given: foo extends bar extends Exception
    83       // throw bar can be caught by catch foo, catch bar, and catch
    84       // Exception, however it can't be caught by any handlers without
    85       // bar in its type hierarchy.
    86       if (handler_klass->is_subtype_of(klass)) {
    87         return true;
    88       }
    89     }
    90   }
    92   return false;
    93 }
    96 bool XHandlers::equals(XHandlers* others) const {
    97   if (others == NULL) return false;
    98   if (length() != others->length()) return false;
   100   for (int i = 0; i < length(); i++) {
   101     if (!handler_at(i)->equals(others->handler_at(i))) return false;
   102   }
   103   return true;
   104 }
   106 bool XHandler::equals(XHandler* other) const {
   107   assert(entry_pco() != -1 && other->entry_pco() != -1, "must have entry_pco");
   109   if (entry_pco() != other->entry_pco()) return false;
   110   if (scope_count() != other->scope_count()) return false;
   111   if (_desc != other->_desc) return false;
   113   assert(entry_block() == other->entry_block(), "entry_block must be equal when entry_pco is equal");
   114   return true;
   115 }
   118 // Implementation of IRScope
   120 BlockBegin* IRScope::header_block(BlockBegin* entry, BlockBegin::Flag f, ValueStack* state) {
   121   if (entry == NULL) return NULL;
   122   assert(entry->is_set(f), "entry/flag mismatch");
   123   // create header block
   124   BlockBegin* h = new BlockBegin(entry->bci());
   125   BlockEnd* g = new Goto(entry, false);
   126   h->set_next(g, entry->bci());
   127   h->set_end(g);
   128   h->set(f);
   129   // setup header block end state
   130   ValueStack* s = state->copy(); // can use copy since stack is empty (=> no phis)
   131   assert(s->stack_is_empty(), "must have empty stack at entry point");
   132   g->set_state(s);
   133   return h;
   134 }
   137 BlockBegin* IRScope::build_graph(Compilation* compilation, int osr_bci) {
   138   GraphBuilder gm(compilation, this);
   139   NOT_PRODUCT(if (PrintValueNumbering && Verbose) gm.print_stats());
   140   if (compilation->bailed_out()) return NULL;
   141   return gm.start();
   142 }
   145 IRScope::IRScope(Compilation* compilation, IRScope* caller, int caller_bci, ciMethod* method, int osr_bci, bool create_graph)
   146 : _callees(2)
   147 , _compilation(compilation)
   148 , _lock_stack_size(-1)
   149 , _requires_phi_function(method->max_locals())
   150 {
   151   _caller             = caller;
   152   _caller_bci         = caller == NULL ? -1 : caller_bci;
   153   _caller_state       = NULL; // Must be set later if needed
   154   _level              = caller == NULL ?  0 : caller->level() + 1;
   155   _method             = method;
   156   _xhandlers          = new XHandlers(method);
   157   _number_of_locks    = 0;
   158   _monitor_pairing_ok = method->has_balanced_monitors();
   159   _start              = NULL;
   161   if (osr_bci == -1) {
   162     _requires_phi_function.clear();
   163   } else {
   164         // selective creation of phi functions is not possibel in osr-methods
   165     _requires_phi_function.set_range(0, method->max_locals());
   166   }
   168   assert(method->holder()->is_loaded() , "method holder must be loaded");
   170   // build graph if monitor pairing is ok
   171   if (create_graph && monitor_pairing_ok()) _start = build_graph(compilation, osr_bci);
   172 }
   175 int IRScope::max_stack() const {
   176   int my_max = method()->max_stack();
   177   int callee_max = 0;
   178   for (int i = 0; i < number_of_callees(); i++) {
   179     callee_max = MAX2(callee_max, callee_no(i)->max_stack());
   180   }
   181   return my_max + callee_max;
   182 }
   185 void IRScope::compute_lock_stack_size() {
   186   if (!InlineMethodsWithExceptionHandlers) {
   187     _lock_stack_size = 0;
   188     return;
   189   }
   191   // Figure out whether we have to preserve expression stack elements
   192   // for parent scopes, and if so, how many
   193   IRScope* cur_scope = this;
   194   while (cur_scope != NULL && !cur_scope->xhandlers()->has_handlers()) {
   195     cur_scope = cur_scope->caller();
   196   }
   197   _lock_stack_size = (cur_scope == NULL ? 0 :
   198                       (cur_scope->caller_state() == NULL ? 0 :
   199                        cur_scope->caller_state()->stack_size()));
   200 }
   202 int IRScope::top_scope_bci() const {
   203   assert(!is_top_scope(), "no correct answer for top scope possible");
   204   const IRScope* scope = this;
   205   while (!scope->caller()->is_top_scope()) {
   206     scope = scope->caller();
   207   }
   208   return scope->caller_bci();
   209 }
   211 bool IRScopeDebugInfo::should_reexecute() {
   212   ciMethod* cur_method = scope()->method();
   213   int       cur_bci    = bci();
   214   if (cur_method != NULL && cur_bci != SynchronizationEntryBCI) {
   215     Bytecodes::Code code = cur_method->java_code_at_bci(cur_bci);
   216     return Interpreter::bytecode_should_reexecute(code);
   217   } else
   218     return false;
   219 }
   222 // Implementation of CodeEmitInfo
   224 // Stack must be NON-null
   225 CodeEmitInfo::CodeEmitInfo(int bci, ValueStack* stack, XHandlers* exception_handlers)
   226   : _scope(stack->scope())
   227   , _bci(bci)
   228   , _scope_debug_info(NULL)
   229   , _oop_map(NULL)
   230   , _stack(stack)
   231   , _exception_handlers(exception_handlers)
   232   , _next(NULL)
   233   , _id(-1)
   234   , _is_method_handle_invoke(false) {
   235   assert(_stack != NULL, "must be non null");
   236   assert(_bci == SynchronizationEntryBCI || Bytecodes::is_defined(scope()->method()->java_code_at_bci(_bci)), "make sure bci points at a real bytecode");
   237 }
   240 CodeEmitInfo::CodeEmitInfo(CodeEmitInfo* info, bool lock_stack_only)
   241   : _scope(info->_scope)
   242   , _exception_handlers(NULL)
   243   , _bci(info->_bci)
   244   , _scope_debug_info(NULL)
   245   , _oop_map(NULL)
   246   , _is_method_handle_invoke(info->_is_method_handle_invoke) {
   247   if (lock_stack_only) {
   248     if (info->_stack != NULL) {
   249       _stack = info->_stack->copy_locks();
   250     } else {
   251       _stack = NULL;
   252     }
   253   } else {
   254     _stack = info->_stack;
   255   }
   257   // deep copy of exception handlers
   258   if (info->_exception_handlers != NULL) {
   259     _exception_handlers = new XHandlers(info->_exception_handlers);
   260   }
   261 }
   264 void CodeEmitInfo::record_debug_info(DebugInformationRecorder* recorder, int pc_offset) {
   265   // record the safepoint before recording the debug info for enclosing scopes
   266   recorder->add_safepoint(pc_offset, _oop_map->deep_copy());
   267   _scope_debug_info->record_debug_info(recorder, pc_offset, true/*topmost*/, _is_method_handle_invoke);
   268   recorder->end_safepoint(pc_offset);
   269 }
   272 void CodeEmitInfo::add_register_oop(LIR_Opr opr) {
   273   assert(_oop_map != NULL, "oop map must already exist");
   274   assert(opr->is_single_cpu(), "should not call otherwise");
   276   int frame_size = frame_map()->framesize();
   277   int arg_count = frame_map()->oop_map_arg_count();
   278   VMReg name = frame_map()->regname(opr);
   279   _oop_map->set_oop(name);
   280 }
   285 // Implementation of IR
   287 IR::IR(Compilation* compilation, ciMethod* method, int osr_bci) :
   288     _locals_size(in_WordSize(-1))
   289   , _num_loops(0) {
   290   // setup IR fields
   291   _compilation = compilation;
   292   _top_scope   = new IRScope(compilation, NULL, -1, method, osr_bci, true);
   293   _code        = NULL;
   294 }
   297 void IR::optimize() {
   298   Optimizer opt(this);
   299   if (!compilation()->profile_branches()) {
   300     if (DoCEE) {
   301       opt.eliminate_conditional_expressions();
   302 #ifndef PRODUCT
   303       if (PrintCFG || PrintCFG1) { tty->print_cr("CFG after CEE"); print(true); }
   304       if (PrintIR  || PrintIR1 ) { tty->print_cr("IR after CEE"); print(false); }
   305 #endif
   306     }
   307     if (EliminateBlocks) {
   308       opt.eliminate_blocks();
   309 #ifndef PRODUCT
   310       if (PrintCFG || PrintCFG1) { tty->print_cr("CFG after block elimination"); print(true); }
   311       if (PrintIR  || PrintIR1 ) { tty->print_cr("IR after block elimination"); print(false); }
   312 #endif
   313     }
   314   }
   315   if (EliminateNullChecks) {
   316     opt.eliminate_null_checks();
   317 #ifndef PRODUCT
   318     if (PrintCFG || PrintCFG1) { tty->print_cr("CFG after null check elimination"); print(true); }
   319     if (PrintIR  || PrintIR1 ) { tty->print_cr("IR after null check elimination"); print(false); }
   320 #endif
   321   }
   322 }
   325 static int sort_pairs(BlockPair** a, BlockPair** b) {
   326   if ((*a)->from() == (*b)->from()) {
   327     return (*a)->to()->block_id() - (*b)->to()->block_id();
   328   } else {
   329     return (*a)->from()->block_id() - (*b)->from()->block_id();
   330   }
   331 }
   334 class CriticalEdgeFinder: public BlockClosure {
   335   BlockPairList blocks;
   336   IR*       _ir;
   338  public:
   339   CriticalEdgeFinder(IR* ir): _ir(ir) {}
   340   void block_do(BlockBegin* bb) {
   341     BlockEnd* be = bb->end();
   342     int nos = be->number_of_sux();
   343     if (nos >= 2) {
   344       for (int i = 0; i < nos; i++) {
   345         BlockBegin* sux = be->sux_at(i);
   346         if (sux->number_of_preds() >= 2) {
   347           blocks.append(new BlockPair(bb, sux));
   348         }
   349       }
   350     }
   351   }
   353   void split_edges() {
   354     BlockPair* last_pair = NULL;
   355     blocks.sort(sort_pairs);
   356     for (int i = 0; i < blocks.length(); i++) {
   357       BlockPair* pair = blocks.at(i);
   358       if (last_pair != NULL && pair->is_same(last_pair)) continue;
   359       BlockBegin* from = pair->from();
   360       BlockBegin* to = pair->to();
   361       BlockBegin* split = from->insert_block_between(to);
   362 #ifndef PRODUCT
   363       if ((PrintIR || PrintIR1) && Verbose) {
   364         tty->print_cr("Split critical edge B%d -> B%d (new block B%d)",
   365                       from->block_id(), to->block_id(), split->block_id());
   366       }
   367 #endif
   368       last_pair = pair;
   369     }
   370   }
   371 };
   373 void IR::split_critical_edges() {
   374   CriticalEdgeFinder cef(this);
   376   iterate_preorder(&cef);
   377   cef.split_edges();
   378 }
   381 class UseCountComputer: public ValueVisitor, BlockClosure {
   382  private:
   383   void visit(Value* n) {
   384     // Local instructions and Phis for expression stack values at the
   385     // start of basic blocks are not added to the instruction list
   386     if ((*n)->bci() == -99 && (*n)->as_Local() == NULL &&
   387         (*n)->as_Phi() == NULL) {
   388       assert(false, "a node was not appended to the graph");
   389       Compilation::current()->bailout("a node was not appended to the graph");
   390     }
   391     // use n's input if not visited before
   392     if (!(*n)->is_pinned() && !(*n)->has_uses()) {
   393       // note: a) if the instruction is pinned, it will be handled by compute_use_count
   394       //       b) if the instruction has uses, it was touched before
   395       //       => in both cases we don't need to update n's values
   396       uses_do(n);
   397     }
   398     // use n
   399     (*n)->_use_count++;
   400   }
   402   Values* worklist;
   403   int depth;
   404   enum {
   405     max_recurse_depth = 20
   406   };
   408   void uses_do(Value* n) {
   409     depth++;
   410     if (depth > max_recurse_depth) {
   411       // don't allow the traversal to recurse too deeply
   412       worklist->push(*n);
   413     } else {
   414       (*n)->input_values_do(this);
   415       // special handling for some instructions
   416       if ((*n)->as_BlockEnd() != NULL) {
   417         // note on BlockEnd:
   418         //   must 'use' the stack only if the method doesn't
   419         //   terminate, however, in those cases stack is empty
   420         (*n)->state_values_do(this);
   421       }
   422     }
   423     depth--;
   424   }
   426   void block_do(BlockBegin* b) {
   427     depth = 0;
   428     // process all pinned nodes as the roots of expression trees
   429     for (Instruction* n = b; n != NULL; n = n->next()) {
   430       if (n->is_pinned()) uses_do(&n);
   431     }
   432     assert(depth == 0, "should have counted back down");
   434     // now process any unpinned nodes which recursed too deeply
   435     while (worklist->length() > 0) {
   436       Value t = worklist->pop();
   437       if (!t->is_pinned()) {
   438         // compute the use count
   439         uses_do(&t);
   441         // pin the instruction so that LIRGenerator doesn't recurse
   442         // too deeply during it's evaluation.
   443         t->pin();
   444       }
   445     }
   446     assert(depth == 0, "should have counted back down");
   447   }
   449   UseCountComputer() {
   450     worklist = new Values();
   451     depth = 0;
   452   }
   454  public:
   455   static void compute(BlockList* blocks) {
   456     UseCountComputer ucc;
   457     blocks->iterate_backward(&ucc);
   458   }
   459 };
   462 // helper macro for short definition of trace-output inside code
   463 #ifndef PRODUCT
   464   #define TRACE_LINEAR_SCAN(level, code)       \
   465     if (TraceLinearScanLevel >= level) {       \
   466       code;                                    \
   467     }
   468 #else
   469   #define TRACE_LINEAR_SCAN(level, code)
   470 #endif
   472 class ComputeLinearScanOrder : public StackObj {
   473  private:
   474   int        _max_block_id;        // the highest block_id of a block
   475   int        _num_blocks;          // total number of blocks (smaller than _max_block_id)
   476   int        _num_loops;           // total number of loops
   477   bool       _iterative_dominators;// method requires iterative computation of dominatiors
   479   BlockList* _linear_scan_order;   // the resulting list of blocks in correct order
   481   BitMap     _visited_blocks;      // used for recursive processing of blocks
   482   BitMap     _active_blocks;       // used for recursive processing of blocks
   483   BitMap     _dominator_blocks;    // temproary BitMap used for computation of dominator
   484   intArray   _forward_branches;    // number of incoming forward branches for each block
   485   BlockList  _loop_end_blocks;     // list of all loop end blocks collected during count_edges
   486   BitMap2D   _loop_map;            // two-dimensional bit set: a bit is set if a block is contained in a loop
   487   BlockList  _work_list;           // temporary list (used in mark_loops and compute_order)
   489   Compilation* _compilation;
   491   // accessors for _visited_blocks and _active_blocks
   492   void init_visited()                     { _active_blocks.clear(); _visited_blocks.clear(); }
   493   bool is_visited(BlockBegin* b) const    { return _visited_blocks.at(b->block_id()); }
   494   bool is_active(BlockBegin* b) const     { return _active_blocks.at(b->block_id()); }
   495   void set_visited(BlockBegin* b)         { assert(!is_visited(b), "already set"); _visited_blocks.set_bit(b->block_id()); }
   496   void set_active(BlockBegin* b)          { assert(!is_active(b), "already set");  _active_blocks.set_bit(b->block_id()); }
   497   void clear_active(BlockBegin* b)        { assert(is_active(b), "not already");   _active_blocks.clear_bit(b->block_id()); }
   499   // accessors for _forward_branches
   500   void inc_forward_branches(BlockBegin* b) { _forward_branches.at_put(b->block_id(), _forward_branches.at(b->block_id()) + 1); }
   501   int  dec_forward_branches(BlockBegin* b) { _forward_branches.at_put(b->block_id(), _forward_branches.at(b->block_id()) - 1); return _forward_branches.at(b->block_id()); }
   503   // accessors for _loop_map
   504   bool is_block_in_loop   (int loop_idx, BlockBegin* b) const { return _loop_map.at(loop_idx, b->block_id()); }
   505   void set_block_in_loop  (int loop_idx, BlockBegin* b)       { _loop_map.set_bit(loop_idx, b->block_id()); }
   506   void clear_block_in_loop(int loop_idx, int block_id)        { _loop_map.clear_bit(loop_idx, block_id); }
   508   // count edges between blocks
   509   void count_edges(BlockBegin* cur, BlockBegin* parent);
   511   // loop detection
   512   void mark_loops();
   513   void clear_non_natural_loops(BlockBegin* start_block);
   514   void assign_loop_depth(BlockBegin* start_block);
   516   // computation of final block order
   517   BlockBegin* common_dominator(BlockBegin* a, BlockBegin* b);
   518   void compute_dominator(BlockBegin* cur, BlockBegin* parent);
   519   int  compute_weight(BlockBegin* cur);
   520   bool ready_for_processing(BlockBegin* cur);
   521   void sort_into_work_list(BlockBegin* b);
   522   void append_block(BlockBegin* cur);
   523   void compute_order(BlockBegin* start_block);
   525   // fixup of dominators for non-natural loops
   526   bool compute_dominators_iter();
   527   void compute_dominators();
   529   // debug functions
   530   NOT_PRODUCT(void print_blocks();)
   531   DEBUG_ONLY(void verify();)
   533   Compilation* compilation() const { return _compilation; }
   534  public:
   535   ComputeLinearScanOrder(Compilation* c, BlockBegin* start_block);
   537   // accessors for final result
   538   BlockList* linear_scan_order() const    { return _linear_scan_order; }
   539   int        num_loops() const            { return _num_loops; }
   540 };
   543 ComputeLinearScanOrder::ComputeLinearScanOrder(Compilation* c, BlockBegin* start_block) :
   544   _max_block_id(BlockBegin::number_of_blocks()),
   545   _num_blocks(0),
   546   _num_loops(0),
   547   _iterative_dominators(false),
   548   _visited_blocks(_max_block_id),
   549   _active_blocks(_max_block_id),
   550   _dominator_blocks(_max_block_id),
   551   _forward_branches(_max_block_id, 0),
   552   _loop_end_blocks(8),
   553   _work_list(8),
   554   _linear_scan_order(NULL), // initialized later with correct size
   555   _loop_map(0, 0),          // initialized later with correct size
   556   _compilation(c)
   557 {
   558   TRACE_LINEAR_SCAN(2, "***** computing linear-scan block order");
   560   init_visited();
   561   count_edges(start_block, NULL);
   563   if (compilation()->is_profiling()) {
   564     compilation()->method()->method_data()->set_compilation_stats(_num_loops, _num_blocks);
   565   }
   567   if (_num_loops > 0) {
   568     mark_loops();
   569     clear_non_natural_loops(start_block);
   570     assign_loop_depth(start_block);
   571   }
   573   compute_order(start_block);
   574   compute_dominators();
   576   NOT_PRODUCT(print_blocks());
   577   DEBUG_ONLY(verify());
   578 }
   581 // Traverse the CFG:
   582 // * count total number of blocks
   583 // * count all incoming edges and backward incoming edges
   584 // * number loop header blocks
   585 // * create a list with all loop end blocks
   586 void ComputeLinearScanOrder::count_edges(BlockBegin* cur, BlockBegin* parent) {
   587   TRACE_LINEAR_SCAN(3, tty->print_cr("Enter count_edges for block B%d coming from B%d", cur->block_id(), parent != NULL ? parent->block_id() : -1));
   588   assert(cur->dominator() == NULL, "dominator already initialized");
   590   if (is_active(cur)) {
   591     TRACE_LINEAR_SCAN(3, tty->print_cr("backward branch"));
   592     assert(is_visited(cur), "block must be visisted when block is active");
   593     assert(parent != NULL, "must have parent");
   595     cur->set(BlockBegin::linear_scan_loop_header_flag);
   596     cur->set(BlockBegin::backward_branch_target_flag);
   598     parent->set(BlockBegin::linear_scan_loop_end_flag);
   600     // When a loop header is also the start of an exception handler, then the backward branch is
   601     // an exception edge. Because such edges are usually critical edges which cannot be split, the
   602     // loop must be excluded here from processing.
   603     if (cur->is_set(BlockBegin::exception_entry_flag)) {
   604       // Make sure that dominators are correct in this weird situation
   605       _iterative_dominators = true;
   606       return;
   607     }
   608     assert(parent->number_of_sux() == 1 && parent->sux_at(0) == cur,
   609            "loop end blocks must have one successor (critical edges are split)");
   611     _loop_end_blocks.append(parent);
   612     return;
   613   }
   615   // increment number of incoming forward branches
   616   inc_forward_branches(cur);
   618   if (is_visited(cur)) {
   619     TRACE_LINEAR_SCAN(3, tty->print_cr("block already visited"));
   620     return;
   621   }
   623   _num_blocks++;
   624   set_visited(cur);
   625   set_active(cur);
   627   // recursive call for all successors
   628   int i;
   629   for (i = cur->number_of_sux() - 1; i >= 0; i--) {
   630     count_edges(cur->sux_at(i), cur);
   631   }
   632   for (i = cur->number_of_exception_handlers() - 1; i >= 0; i--) {
   633     count_edges(cur->exception_handler_at(i), cur);
   634   }
   636   clear_active(cur);
   638   // Each loop has a unique number.
   639   // When multiple loops are nested, assign_loop_depth assumes that the
   640   // innermost loop has the lowest number. This is guaranteed by setting
   641   // the loop number after the recursive calls for the successors above
   642   // have returned.
   643   if (cur->is_set(BlockBegin::linear_scan_loop_header_flag)) {
   644     assert(cur->loop_index() == -1, "cannot set loop-index twice");
   645     TRACE_LINEAR_SCAN(3, tty->print_cr("Block B%d is loop header of loop %d", cur->block_id(), _num_loops));
   647     cur->set_loop_index(_num_loops);
   648     _num_loops++;
   649   }
   651   TRACE_LINEAR_SCAN(3, tty->print_cr("Finished count_edges for block B%d", cur->block_id()));
   652 }
   655 void ComputeLinearScanOrder::mark_loops() {
   656   TRACE_LINEAR_SCAN(3, tty->print_cr("----- marking loops"));
   658   _loop_map = BitMap2D(_num_loops, _max_block_id);
   659   _loop_map.clear();
   661   for (int i = _loop_end_blocks.length() - 1; i >= 0; i--) {
   662     BlockBegin* loop_end   = _loop_end_blocks.at(i);
   663     BlockBegin* loop_start = loop_end->sux_at(0);
   664     int         loop_idx   = loop_start->loop_index();
   666     TRACE_LINEAR_SCAN(3, tty->print_cr("Processing loop from B%d to B%d (loop %d):", loop_start->block_id(), loop_end->block_id(), loop_idx));
   667     assert(loop_end->is_set(BlockBegin::linear_scan_loop_end_flag), "loop end flag must be set");
   668     assert(loop_end->number_of_sux() == 1, "incorrect number of successors");
   669     assert(loop_start->is_set(BlockBegin::linear_scan_loop_header_flag), "loop header flag must be set");
   670     assert(loop_idx >= 0 && loop_idx < _num_loops, "loop index not set");
   671     assert(_work_list.is_empty(), "work list must be empty before processing");
   673     // add the end-block of the loop to the working list
   674     _work_list.push(loop_end);
   675     set_block_in_loop(loop_idx, loop_end);
   676     do {
   677       BlockBegin* cur = _work_list.pop();
   679       TRACE_LINEAR_SCAN(3, tty->print_cr("    processing B%d", cur->block_id()));
   680       assert(is_block_in_loop(loop_idx, cur), "bit in loop map must be set when block is in work list");
   682       // recursive processing of all predecessors ends when start block of loop is reached
   683       if (cur != loop_start && !cur->is_set(BlockBegin::osr_entry_flag)) {
   684         for (int j = cur->number_of_preds() - 1; j >= 0; j--) {
   685           BlockBegin* pred = cur->pred_at(j);
   687           if (!is_block_in_loop(loop_idx, pred) /*&& !pred->is_set(BlockBeginosr_entry_flag)*/) {
   688             // this predecessor has not been processed yet, so add it to work list
   689             TRACE_LINEAR_SCAN(3, tty->print_cr("    pushing B%d", pred->block_id()));
   690             _work_list.push(pred);
   691             set_block_in_loop(loop_idx, pred);
   692           }
   693         }
   694       }
   695     } while (!_work_list.is_empty());
   696   }
   697 }
   700 // check for non-natural loops (loops where the loop header does not dominate
   701 // all other loop blocks = loops with mulitple entries).
   702 // such loops are ignored
   703 void ComputeLinearScanOrder::clear_non_natural_loops(BlockBegin* start_block) {
   704   for (int i = _num_loops - 1; i >= 0; i--) {
   705     if (is_block_in_loop(i, start_block)) {
   706       // loop i contains the entry block of the method
   707       // -> this is not a natural loop, so ignore it
   708       TRACE_LINEAR_SCAN(2, tty->print_cr("Loop %d is non-natural, so it is ignored", i));
   710       for (int block_id = _max_block_id - 1; block_id >= 0; block_id--) {
   711         clear_block_in_loop(i, block_id);
   712       }
   713       _iterative_dominators = true;
   714     }
   715   }
   716 }
   718 void ComputeLinearScanOrder::assign_loop_depth(BlockBegin* start_block) {
   719   TRACE_LINEAR_SCAN(3, "----- computing loop-depth and weight");
   720   init_visited();
   722   assert(_work_list.is_empty(), "work list must be empty before processing");
   723   _work_list.append(start_block);
   725   do {
   726     BlockBegin* cur = _work_list.pop();
   728     if (!is_visited(cur)) {
   729       set_visited(cur);
   730       TRACE_LINEAR_SCAN(4, tty->print_cr("Computing loop depth for block B%d", cur->block_id()));
   732       // compute loop-depth and loop-index for the block
   733       assert(cur->loop_depth() == 0, "cannot set loop-depth twice");
   734       int i;
   735       int loop_depth = 0;
   736       int min_loop_idx = -1;
   737       for (i = _num_loops - 1; i >= 0; i--) {
   738         if (is_block_in_loop(i, cur)) {
   739           loop_depth++;
   740           min_loop_idx = i;
   741         }
   742       }
   743       cur->set_loop_depth(loop_depth);
   744       cur->set_loop_index(min_loop_idx);
   746       // append all unvisited successors to work list
   747       for (i = cur->number_of_sux() - 1; i >= 0; i--) {
   748         _work_list.append(cur->sux_at(i));
   749       }
   750       for (i = cur->number_of_exception_handlers() - 1; i >= 0; i--) {
   751         _work_list.append(cur->exception_handler_at(i));
   752       }
   753     }
   754   } while (!_work_list.is_empty());
   755 }
   758 BlockBegin* ComputeLinearScanOrder::common_dominator(BlockBegin* a, BlockBegin* b) {
   759   assert(a != NULL && b != NULL, "must have input blocks");
   761   _dominator_blocks.clear();
   762   while (a != NULL) {
   763     _dominator_blocks.set_bit(a->block_id());
   764     assert(a->dominator() != NULL || a == _linear_scan_order->at(0), "dominator must be initialized");
   765     a = a->dominator();
   766   }
   767   while (b != NULL && !_dominator_blocks.at(b->block_id())) {
   768     assert(b->dominator() != NULL || b == _linear_scan_order->at(0), "dominator must be initialized");
   769     b = b->dominator();
   770   }
   772   assert(b != NULL, "could not find dominator");
   773   return b;
   774 }
   776 void ComputeLinearScanOrder::compute_dominator(BlockBegin* cur, BlockBegin* parent) {
   777   if (cur->dominator() == NULL) {
   778     TRACE_LINEAR_SCAN(4, tty->print_cr("DOM: initializing dominator of B%d to B%d", cur->block_id(), parent->block_id()));
   779     cur->set_dominator(parent);
   781   } else if (!(cur->is_set(BlockBegin::linear_scan_loop_header_flag) && parent->is_set(BlockBegin::linear_scan_loop_end_flag))) {
   782     TRACE_LINEAR_SCAN(4, tty->print_cr("DOM: computing dominator of B%d: common dominator of B%d and B%d is B%d", cur->block_id(), parent->block_id(), cur->dominator()->block_id(), common_dominator(cur->dominator(), parent)->block_id()));
   783     assert(cur->number_of_preds() > 1, "");
   784     cur->set_dominator(common_dominator(cur->dominator(), parent));
   785   }
   786 }
   789 int ComputeLinearScanOrder::compute_weight(BlockBegin* cur) {
   790   BlockBegin* single_sux = NULL;
   791   if (cur->number_of_sux() == 1) {
   792     single_sux = cur->sux_at(0);
   793   }
   795   // limit loop-depth to 15 bit (only for security reason, it will never be so big)
   796   int weight = (cur->loop_depth() & 0x7FFF) << 16;
   798   // general macro for short definition of weight flags
   799   // the first instance of INC_WEIGHT_IF has the highest priority
   800   int cur_bit = 15;
   801   #define INC_WEIGHT_IF(condition) if ((condition)) { weight |= (1 << cur_bit); } cur_bit--;
   803   // this is necessery for the (very rare) case that two successing blocks have
   804   // the same loop depth, but a different loop index (can happen for endless loops
   805   // with exception handlers)
   806   INC_WEIGHT_IF(!cur->is_set(BlockBegin::linear_scan_loop_header_flag));
   808   // loop end blocks (blocks that end with a backward branch) are added
   809   // after all other blocks of the loop.
   810   INC_WEIGHT_IF(!cur->is_set(BlockBegin::linear_scan_loop_end_flag));
   812   // critical edge split blocks are prefered because than they have a bigger
   813   // proability to be completely empty
   814   INC_WEIGHT_IF(cur->is_set(BlockBegin::critical_edge_split_flag));
   816   // exceptions should not be thrown in normal control flow, so these blocks
   817   // are added as late as possible
   818   INC_WEIGHT_IF(cur->end()->as_Throw() == NULL  && (single_sux == NULL || single_sux->end()->as_Throw()  == NULL));
   819   INC_WEIGHT_IF(cur->end()->as_Return() == NULL && (single_sux == NULL || single_sux->end()->as_Return() == NULL));
   821   // exceptions handlers are added as late as possible
   822   INC_WEIGHT_IF(!cur->is_set(BlockBegin::exception_entry_flag));
   824   // guarantee that weight is > 0
   825   weight |= 1;
   827   #undef INC_WEIGHT_IF
   828   assert(cur_bit >= 0, "too many flags");
   829   assert(weight > 0, "weight cannot become negative");
   831   return weight;
   832 }
   834 bool ComputeLinearScanOrder::ready_for_processing(BlockBegin* cur) {
   835   // Discount the edge just traveled.
   836   // When the number drops to zero, all forward branches were processed
   837   if (dec_forward_branches(cur) != 0) {
   838     return false;
   839   }
   841   assert(_linear_scan_order->index_of(cur) == -1, "block already processed (block can be ready only once)");
   842   assert(_work_list.index_of(cur) == -1, "block already in work-list (block can be ready only once)");
   843   return true;
   844 }
   846 void ComputeLinearScanOrder::sort_into_work_list(BlockBegin* cur) {
   847   assert(_work_list.index_of(cur) == -1, "block already in work list");
   849   int cur_weight = compute_weight(cur);
   851   // the linear_scan_number is used to cache the weight of a block
   852   cur->set_linear_scan_number(cur_weight);
   854 #ifndef PRODUCT
   855   if (StressLinearScan) {
   856     _work_list.insert_before(0, cur);
   857     return;
   858   }
   859 #endif
   861   _work_list.append(NULL); // provide space for new element
   863   int insert_idx = _work_list.length() - 1;
   864   while (insert_idx > 0 && _work_list.at(insert_idx - 1)->linear_scan_number() > cur_weight) {
   865     _work_list.at_put(insert_idx, _work_list.at(insert_idx - 1));
   866     insert_idx--;
   867   }
   868   _work_list.at_put(insert_idx, cur);
   870   TRACE_LINEAR_SCAN(3, tty->print_cr("Sorted B%d into worklist. new worklist:", cur->block_id()));
   871   TRACE_LINEAR_SCAN(3, for (int i = 0; i < _work_list.length(); i++) tty->print_cr("%8d B%2d  weight:%6x", i, _work_list.at(i)->block_id(), _work_list.at(i)->linear_scan_number()));
   873 #ifdef ASSERT
   874   for (int i = 0; i < _work_list.length(); i++) {
   875     assert(_work_list.at(i)->linear_scan_number() > 0, "weight not set");
   876     assert(i == 0 || _work_list.at(i - 1)->linear_scan_number() <= _work_list.at(i)->linear_scan_number(), "incorrect order in worklist");
   877   }
   878 #endif
   879 }
   881 void ComputeLinearScanOrder::append_block(BlockBegin* cur) {
   882   TRACE_LINEAR_SCAN(3, tty->print_cr("appending block B%d (weight 0x%6x) to linear-scan order", cur->block_id(), cur->linear_scan_number()));
   883   assert(_linear_scan_order->index_of(cur) == -1, "cannot add the same block twice");
   885   // currently, the linear scan order and code emit order are equal.
   886   // therefore the linear_scan_number and the weight of a block must also
   887   // be equal.
   888   cur->set_linear_scan_number(_linear_scan_order->length());
   889   _linear_scan_order->append(cur);
   890 }
   892 void ComputeLinearScanOrder::compute_order(BlockBegin* start_block) {
   893   TRACE_LINEAR_SCAN(3, "----- computing final block order");
   895   // the start block is always the first block in the linear scan order
   896   _linear_scan_order = new BlockList(_num_blocks);
   897   append_block(start_block);
   899   assert(start_block->end()->as_Base() != NULL, "start block must end with Base-instruction");
   900   BlockBegin* std_entry = ((Base*)start_block->end())->std_entry();
   901   BlockBegin* osr_entry = ((Base*)start_block->end())->osr_entry();
   903   BlockBegin* sux_of_osr_entry = NULL;
   904   if (osr_entry != NULL) {
   905     // special handling for osr entry:
   906     // ignore the edge between the osr entry and its successor for processing
   907     // the osr entry block is added manually below
   908     assert(osr_entry->number_of_sux() == 1, "osr entry must have exactly one successor");
   909     assert(osr_entry->sux_at(0)->number_of_preds() >= 2, "sucessor of osr entry must have two predecessors (otherwise it is not present in normal control flow");
   911     sux_of_osr_entry = osr_entry->sux_at(0);
   912     dec_forward_branches(sux_of_osr_entry);
   914     compute_dominator(osr_entry, start_block);
   915     _iterative_dominators = true;
   916   }
   917   compute_dominator(std_entry, start_block);
   919   // start processing with standard entry block
   920   assert(_work_list.is_empty(), "list must be empty before processing");
   922   if (ready_for_processing(std_entry)) {
   923     sort_into_work_list(std_entry);
   924   } else {
   925     assert(false, "the std_entry must be ready for processing (otherwise, the method has no start block)");
   926   }
   928   do {
   929     BlockBegin* cur = _work_list.pop();
   931     if (cur == sux_of_osr_entry) {
   932       // the osr entry block is ignored in normal processing, it is never added to the
   933       // work list. Instead, it is added as late as possible manually here.
   934       append_block(osr_entry);
   935       compute_dominator(cur, osr_entry);
   936     }
   937     append_block(cur);
   939     int i;
   940     int num_sux = cur->number_of_sux();
   941     // changed loop order to get "intuitive" order of if- and else-blocks
   942     for (i = 0; i < num_sux; i++) {
   943       BlockBegin* sux = cur->sux_at(i);
   944       compute_dominator(sux, cur);
   945       if (ready_for_processing(sux)) {
   946         sort_into_work_list(sux);
   947       }
   948     }
   949     num_sux = cur->number_of_exception_handlers();
   950     for (i = 0; i < num_sux; i++) {
   951       BlockBegin* sux = cur->exception_handler_at(i);
   952       compute_dominator(sux, cur);
   953       if (ready_for_processing(sux)) {
   954         sort_into_work_list(sux);
   955       }
   956     }
   957   } while (_work_list.length() > 0);
   958 }
   961 bool ComputeLinearScanOrder::compute_dominators_iter() {
   962   bool changed = false;
   963   int num_blocks = _linear_scan_order->length();
   965   assert(_linear_scan_order->at(0)->dominator() == NULL, "must not have dominator");
   966   assert(_linear_scan_order->at(0)->number_of_preds() == 0, "must not have predecessors");
   967   for (int i = 1; i < num_blocks; i++) {
   968     BlockBegin* block = _linear_scan_order->at(i);
   970     BlockBegin* dominator = block->pred_at(0);
   971     int num_preds = block->number_of_preds();
   972     for (int i = 1; i < num_preds; i++) {
   973       dominator = common_dominator(dominator, block->pred_at(i));
   974     }
   976     if (dominator != block->dominator()) {
   977       TRACE_LINEAR_SCAN(4, tty->print_cr("DOM: updating dominator of B%d from B%d to B%d", block->block_id(), block->dominator()->block_id(), dominator->block_id()));
   979       block->set_dominator(dominator);
   980       changed = true;
   981     }
   982   }
   983   return changed;
   984 }
   986 void ComputeLinearScanOrder::compute_dominators() {
   987   TRACE_LINEAR_SCAN(3, tty->print_cr("----- computing dominators (iterative computation reqired: %d)", _iterative_dominators));
   989   // iterative computation of dominators is only required for methods with non-natural loops
   990   // and OSR-methods. For all other methods, the dominators computed when generating the
   991   // linear scan block order are correct.
   992   if (_iterative_dominators) {
   993     do {
   994       TRACE_LINEAR_SCAN(1, tty->print_cr("DOM: next iteration of fix-point calculation"));
   995     } while (compute_dominators_iter());
   996   }
   998   // check that dominators are correct
   999   assert(!compute_dominators_iter(), "fix point not reached");
  1003 #ifndef PRODUCT
  1004 void ComputeLinearScanOrder::print_blocks() {
  1005   if (TraceLinearScanLevel >= 2) {
  1006     tty->print_cr("----- loop information:");
  1007     for (int block_idx = 0; block_idx < _linear_scan_order->length(); block_idx++) {
  1008       BlockBegin* cur = _linear_scan_order->at(block_idx);
  1010       tty->print("%4d: B%2d: ", cur->linear_scan_number(), cur->block_id());
  1011       for (int loop_idx = 0; loop_idx < _num_loops; loop_idx++) {
  1012         tty->print ("%d ", is_block_in_loop(loop_idx, cur));
  1014       tty->print_cr(" -> loop_index: %2d, loop_depth: %2d", cur->loop_index(), cur->loop_depth());
  1018   if (TraceLinearScanLevel >= 1) {
  1019     tty->print_cr("----- linear-scan block order:");
  1020     for (int block_idx = 0; block_idx < _linear_scan_order->length(); block_idx++) {
  1021       BlockBegin* cur = _linear_scan_order->at(block_idx);
  1022       tty->print("%4d: B%2d    loop: %2d  depth: %2d", cur->linear_scan_number(), cur->block_id(), cur->loop_index(), cur->loop_depth());
  1024       tty->print(cur->is_set(BlockBegin::exception_entry_flag)         ? " ex" : "   ");
  1025       tty->print(cur->is_set(BlockBegin::critical_edge_split_flag)     ? " ce" : "   ");
  1026       tty->print(cur->is_set(BlockBegin::linear_scan_loop_header_flag) ? " lh" : "   ");
  1027       tty->print(cur->is_set(BlockBegin::linear_scan_loop_end_flag)    ? " le" : "   ");
  1029       if (cur->dominator() != NULL) {
  1030         tty->print("    dom: B%d ", cur->dominator()->block_id());
  1031       } else {
  1032         tty->print("    dom: NULL ");
  1035       if (cur->number_of_preds() > 0) {
  1036         tty->print("    preds: ");
  1037         for (int j = 0; j < cur->number_of_preds(); j++) {
  1038           BlockBegin* pred = cur->pred_at(j);
  1039           tty->print("B%d ", pred->block_id());
  1042       if (cur->number_of_sux() > 0) {
  1043         tty->print("    sux: ");
  1044         for (int j = 0; j < cur->number_of_sux(); j++) {
  1045           BlockBegin* sux = cur->sux_at(j);
  1046           tty->print("B%d ", sux->block_id());
  1049       if (cur->number_of_exception_handlers() > 0) {
  1050         tty->print("    ex: ");
  1051         for (int j = 0; j < cur->number_of_exception_handlers(); j++) {
  1052           BlockBegin* ex = cur->exception_handler_at(j);
  1053           tty->print("B%d ", ex->block_id());
  1056       tty->cr();
  1060 #endif
  1062 #ifdef ASSERT
  1063 void ComputeLinearScanOrder::verify() {
  1064   assert(_linear_scan_order->length() == _num_blocks, "wrong number of blocks in list");
  1066   if (StressLinearScan) {
  1067     // blocks are scrambled when StressLinearScan is used
  1068     return;
  1071   // check that all successors of a block have a higher linear-scan-number
  1072   // and that all predecessors of a block have a lower linear-scan-number
  1073   // (only backward branches of loops are ignored)
  1074   int i;
  1075   for (i = 0; i < _linear_scan_order->length(); i++) {
  1076     BlockBegin* cur = _linear_scan_order->at(i);
  1078     assert(cur->linear_scan_number() == i, "incorrect linear_scan_number");
  1079     assert(cur->linear_scan_number() >= 0 && cur->linear_scan_number() == _linear_scan_order->index_of(cur), "incorrect linear_scan_number");
  1081     int j;
  1082     for (j = cur->number_of_sux() - 1; j >= 0; j--) {
  1083       BlockBegin* sux = cur->sux_at(j);
  1085       assert(sux->linear_scan_number() >= 0 && sux->linear_scan_number() == _linear_scan_order->index_of(sux), "incorrect linear_scan_number");
  1086       if (!cur->is_set(BlockBegin::linear_scan_loop_end_flag)) {
  1087         assert(cur->linear_scan_number() < sux->linear_scan_number(), "invalid order");
  1089       if (cur->loop_depth() == sux->loop_depth()) {
  1090         assert(cur->loop_index() == sux->loop_index() || sux->is_set(BlockBegin::linear_scan_loop_header_flag), "successing blocks with same loop depth must have same loop index");
  1094     for (j = cur->number_of_preds() - 1; j >= 0; j--) {
  1095       BlockBegin* pred = cur->pred_at(j);
  1097       assert(pred->linear_scan_number() >= 0 && pred->linear_scan_number() == _linear_scan_order->index_of(pred), "incorrect linear_scan_number");
  1098       if (!cur->is_set(BlockBegin::linear_scan_loop_header_flag)) {
  1099         assert(cur->linear_scan_number() > pred->linear_scan_number(), "invalid order");
  1101       if (cur->loop_depth() == pred->loop_depth()) {
  1102         assert(cur->loop_index() == pred->loop_index() || cur->is_set(BlockBegin::linear_scan_loop_header_flag), "successing blocks with same loop depth must have same loop index");
  1105       assert(cur->dominator()->linear_scan_number() <= cur->pred_at(j)->linear_scan_number(), "dominator must be before predecessors");
  1108     // check dominator
  1109     if (i == 0) {
  1110       assert(cur->dominator() == NULL, "first block has no dominator");
  1111     } else {
  1112       assert(cur->dominator() != NULL, "all but first block must have dominator");
  1114     assert(cur->number_of_preds() != 1 || cur->dominator() == cur->pred_at(0), "Single predecessor must also be dominator");
  1117   // check that all loops are continuous
  1118   for (int loop_idx = 0; loop_idx < _num_loops; loop_idx++) {
  1119     int block_idx = 0;
  1120     assert(!is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx)), "the first block must not be present in any loop");
  1122     // skip blocks before the loop
  1123     while (block_idx < _num_blocks && !is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx))) {
  1124       block_idx++;
  1126     // skip blocks of loop
  1127     while (block_idx < _num_blocks && is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx))) {
  1128       block_idx++;
  1130     // after the first non-loop block, there must not be another loop-block
  1131     while (block_idx < _num_blocks) {
  1132       assert(!is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx)), "loop not continuous in linear-scan order");
  1133       block_idx++;
  1137 #endif
  1140 void IR::compute_code() {
  1141   assert(is_valid(), "IR must be valid");
  1143   ComputeLinearScanOrder compute_order(compilation(), start());
  1144   _num_loops = compute_order.num_loops();
  1145   _code = compute_order.linear_scan_order();
  1149 void IR::compute_use_counts() {
  1150   // make sure all values coming out of this block get evaluated.
  1151   int num_blocks = _code->length();
  1152   for (int i = 0; i < num_blocks; i++) {
  1153     _code->at(i)->end()->state()->pin_stack_for_linear_scan();
  1156   // compute use counts
  1157   UseCountComputer::compute(_code);
  1161 void IR::iterate_preorder(BlockClosure* closure) {
  1162   assert(is_valid(), "IR must be valid");
  1163   start()->iterate_preorder(closure);
  1167 void IR::iterate_postorder(BlockClosure* closure) {
  1168   assert(is_valid(), "IR must be valid");
  1169   start()->iterate_postorder(closure);
  1172 void IR::iterate_linear_scan_order(BlockClosure* closure) {
  1173   linear_scan_order()->iterate_forward(closure);
  1177 #ifndef PRODUCT
  1178 class BlockPrinter: public BlockClosure {
  1179  private:
  1180   InstructionPrinter* _ip;
  1181   bool                _cfg_only;
  1182   bool                _live_only;
  1184  public:
  1185   BlockPrinter(InstructionPrinter* ip, bool cfg_only, bool live_only = false) {
  1186     _ip       = ip;
  1187     _cfg_only = cfg_only;
  1188     _live_only = live_only;
  1191   virtual void block_do(BlockBegin* block) {
  1192     if (_cfg_only) {
  1193       _ip->print_instr(block); tty->cr();
  1194     } else {
  1195       block->print_block(*_ip, _live_only);
  1198 };
  1201 void IR::print(BlockBegin* start, bool cfg_only, bool live_only) {
  1202   ttyLocker ttyl;
  1203   InstructionPrinter ip(!cfg_only);
  1204   BlockPrinter bp(&ip, cfg_only, live_only);
  1205   start->iterate_preorder(&bp);
  1206   tty->cr();
  1209 void IR::print(bool cfg_only, bool live_only) {
  1210   if (is_valid()) {
  1211     print(start(), cfg_only, live_only);
  1212   } else {
  1213     tty->print_cr("invalid IR");
  1218 define_array(BlockListArray, BlockList*)
  1219 define_stack(BlockListList, BlockListArray)
  1221 class PredecessorValidator : public BlockClosure {
  1222  private:
  1223   BlockListList* _predecessors;
  1224   BlockList*     _blocks;
  1226   static int cmp(BlockBegin** a, BlockBegin** b) {
  1227     return (*a)->block_id() - (*b)->block_id();
  1230  public:
  1231   PredecessorValidator(IR* hir) {
  1232     ResourceMark rm;
  1233     _predecessors = new BlockListList(BlockBegin::number_of_blocks(), NULL);
  1234     _blocks = new BlockList();
  1236     int i;
  1237     hir->start()->iterate_preorder(this);
  1238     if (hir->code() != NULL) {
  1239       assert(hir->code()->length() == _blocks->length(), "must match");
  1240       for (i = 0; i < _blocks->length(); i++) {
  1241         assert(hir->code()->contains(_blocks->at(i)), "should be in both lists");
  1245     for (i = 0; i < _blocks->length(); i++) {
  1246       BlockBegin* block = _blocks->at(i);
  1247       BlockList* preds = _predecessors->at(block->block_id());
  1248       if (preds == NULL) {
  1249         assert(block->number_of_preds() == 0, "should be the same");
  1250         continue;
  1253       // clone the pred list so we can mutate it
  1254       BlockList* pred_copy = new BlockList();
  1255       int j;
  1256       for (j = 0; j < block->number_of_preds(); j++) {
  1257         pred_copy->append(block->pred_at(j));
  1259       // sort them in the same order
  1260       preds->sort(cmp);
  1261       pred_copy->sort(cmp);
  1262       int length = MIN2(preds->length(), block->number_of_preds());
  1263       for (j = 0; j < block->number_of_preds(); j++) {
  1264         assert(preds->at(j) == pred_copy->at(j), "must match");
  1267       assert(preds->length() == block->number_of_preds(), "should be the same");
  1271   virtual void block_do(BlockBegin* block) {
  1272     _blocks->append(block);
  1273     BlockEnd* be = block->end();
  1274     int n = be->number_of_sux();
  1275     int i;
  1276     for (i = 0; i < n; i++) {
  1277       BlockBegin* sux = be->sux_at(i);
  1278       assert(!sux->is_set(BlockBegin::exception_entry_flag), "must not be xhandler");
  1280       BlockList* preds = _predecessors->at_grow(sux->block_id(), NULL);
  1281       if (preds == NULL) {
  1282         preds = new BlockList();
  1283         _predecessors->at_put(sux->block_id(), preds);
  1285       preds->append(block);
  1288     n = block->number_of_exception_handlers();
  1289     for (i = 0; i < n; i++) {
  1290       BlockBegin* sux = block->exception_handler_at(i);
  1291       assert(sux->is_set(BlockBegin::exception_entry_flag), "must be xhandler");
  1293       BlockList* preds = _predecessors->at_grow(sux->block_id(), NULL);
  1294       if (preds == NULL) {
  1295         preds = new BlockList();
  1296         _predecessors->at_put(sux->block_id(), preds);
  1298       preds->append(block);
  1301 };
  1303 void IR::verify() {
  1304 #ifdef ASSERT
  1305   PredecessorValidator pv(this);
  1306 #endif
  1309 #endif // PRODUCT
  1311 void SubstitutionResolver::visit(Value* v) {
  1312   Value v0 = *v;
  1313   if (v0) {
  1314     Value vs = v0->subst();
  1315     if (vs != v0) {
  1316       *v = v0->subst();
  1321 #ifdef ASSERT
  1322 class SubstitutionChecker: public ValueVisitor {
  1323   void visit(Value* v) {
  1324     Value v0 = *v;
  1325     if (v0) {
  1326       Value vs = v0->subst();
  1327       assert(vs == v0, "missed substitution");
  1330 };
  1331 #endif
  1334 void SubstitutionResolver::block_do(BlockBegin* block) {
  1335   Instruction* last = NULL;
  1336   for (Instruction* n = block; n != NULL;) {
  1337     n->values_do(this);
  1338     // need to remove this instruction from the instruction stream
  1339     if (n->subst() != n) {
  1340       assert(last != NULL, "must have last");
  1341       last->set_next(n->next(), n->next()->bci());
  1342     } else {
  1343       last = n;
  1345     n = last->next();
  1348 #ifdef ASSERT
  1349   SubstitutionChecker check_substitute;
  1350   if (block->state()) block->state()->values_do(&check_substitute);
  1351   block->block_values_do(&check_substitute);
  1352   if (block->end() && block->end()->state()) block->end()->state()->values_do(&check_substitute);
  1353 #endif

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