1 /*
   2  * Copyright 1997-2008 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  20  * CA 95054 USA or visit www.sun.com if you need additional information or
  21  * have any questions.
  22  *
  23  */
  24 
  25 // Portions of code courtesy of Clifford Click
  26 
  27 // Optimization - Graph Style
  28 
  29 #include "incls/_precompiled.incl"
  30 #include "incls/_callnode.cpp.incl"
  31 
  32 //=============================================================================
  33 uint StartNode::size_of() const { return sizeof(*this); }
  34 uint StartNode::cmp( const Node &n ) const
  35 { return _domain == ((StartNode&)n)._domain; }
  36 const Type *StartNode::bottom_type() const { return _domain; }
  37 const Type *StartNode::Value(PhaseTransform *phase) const { return _domain; }
  38 #ifndef PRODUCT
  39 void StartNode::dump_spec(outputStream *st) const { st->print(" #"); _domain->dump_on(st);}
  40 #endif
  41 
  42 //------------------------------Ideal------------------------------------------
  43 Node *StartNode::Ideal(PhaseGVN *phase, bool can_reshape){
  44   return remove_dead_region(phase, can_reshape) ? this : NULL;
  45 }
  46 
  47 //------------------------------calling_convention-----------------------------
  48 void StartNode::calling_convention( BasicType* sig_bt, VMRegPair *parm_regs, uint argcnt ) const {
  49   Matcher::calling_convention( sig_bt, parm_regs, argcnt, false );
  50 }
  51 
  52 //------------------------------Registers--------------------------------------
  53 const RegMask &StartNode::in_RegMask(uint) const {
  54   return RegMask::Empty;
  55 }
  56 
  57 //------------------------------match------------------------------------------
  58 // Construct projections for incoming parameters, and their RegMask info
  59 Node *StartNode::match( const ProjNode *proj, const Matcher *match ) {
  60   switch (proj->_con) {
  61   case TypeFunc::Control:
  62   case TypeFunc::I_O:
  63   case TypeFunc::Memory:
  64     return new (match->C, 1) MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj);
  65   case TypeFunc::FramePtr:
  66     return new (match->C, 1) MachProjNode(this,proj->_con,Matcher::c_frame_ptr_mask, Op_RegP);
  67   case TypeFunc::ReturnAdr:
  68     return new (match->C, 1) MachProjNode(this,proj->_con,match->_return_addr_mask,Op_RegP);
  69   case TypeFunc::Parms:
  70   default: {
  71       uint parm_num = proj->_con - TypeFunc::Parms;
  72       const Type *t = _domain->field_at(proj->_con);
  73       if (t->base() == Type::Half)  // 2nd half of Longs and Doubles
  74         return new (match->C, 1) ConNode(Type::TOP);
  75       uint ideal_reg = Matcher::base2reg[t->base()];
  76       RegMask &rm = match->_calling_convention_mask[parm_num];
  77       return new (match->C, 1) MachProjNode(this,proj->_con,rm,ideal_reg);
  78     }
  79   }
  80   return NULL;
  81 }
  82 
  83 //------------------------------StartOSRNode----------------------------------
  84 // The method start node for an on stack replacement adapter
  85 
  86 //------------------------------osr_domain-----------------------------
  87 const TypeTuple *StartOSRNode::osr_domain() {
  88   const Type **fields = TypeTuple::fields(2);
  89   fields[TypeFunc::Parms+0] = TypeRawPtr::BOTTOM;  // address of osr buffer
  90 
  91   return TypeTuple::make(TypeFunc::Parms+1, fields);
  92 }
  93 
  94 //=============================================================================
  95 const char * const ParmNode::names[TypeFunc::Parms+1] = {
  96   "Control", "I_O", "Memory", "FramePtr", "ReturnAdr", "Parms"
  97 };
  98 
  99 #ifndef PRODUCT
 100 void ParmNode::dump_spec(outputStream *st) const {
 101   if( _con < TypeFunc::Parms ) {
 102     st->print(names[_con]);
 103   } else {
 104     st->print("Parm%d: ",_con-TypeFunc::Parms);
 105     // Verbose and WizardMode dump bottom_type for all nodes
 106     if( !Verbose && !WizardMode )   bottom_type()->dump_on(st);
 107   }
 108 }
 109 #endif
 110 
 111 uint ParmNode::ideal_reg() const {
 112   switch( _con ) {
 113   case TypeFunc::Control  : // fall through
 114   case TypeFunc::I_O      : // fall through
 115   case TypeFunc::Memory   : return 0;
 116   case TypeFunc::FramePtr : // fall through
 117   case TypeFunc::ReturnAdr: return Op_RegP;
 118   default                 : assert( _con > TypeFunc::Parms, "" );
 119     // fall through
 120   case TypeFunc::Parms    : {
 121     // Type of argument being passed
 122     const Type *t = in(0)->as_Start()->_domain->field_at(_con);
 123     return Matcher::base2reg[t->base()];
 124   }
 125   }
 126   ShouldNotReachHere();
 127   return 0;
 128 }
 129 
 130 //=============================================================================
 131 ReturnNode::ReturnNode(uint edges, Node *cntrl, Node *i_o, Node *memory, Node *frameptr, Node *retadr ) : Node(edges) {
 132   init_req(TypeFunc::Control,cntrl);
 133   init_req(TypeFunc::I_O,i_o);
 134   init_req(TypeFunc::Memory,memory);
 135   init_req(TypeFunc::FramePtr,frameptr);
 136   init_req(TypeFunc::ReturnAdr,retadr);
 137 }
 138 
 139 Node *ReturnNode::Ideal(PhaseGVN *phase, bool can_reshape){
 140   return remove_dead_region(phase, can_reshape) ? this : NULL;
 141 }
 142 
 143 const Type *ReturnNode::Value( PhaseTransform *phase ) const {
 144   return ( phase->type(in(TypeFunc::Control)) == Type::TOP)
 145     ? Type::TOP
 146     : Type::BOTTOM;
 147 }
 148 
 149 // Do we Match on this edge index or not?  No edges on return nodes
 150 uint ReturnNode::match_edge(uint idx) const {
 151   return 0;
 152 }
 153 
 154 
 155 #ifndef PRODUCT
 156 void ReturnNode::dump_req() const {
 157   // Dump the required inputs, enclosed in '(' and ')'
 158   uint i;                       // Exit value of loop
 159   for( i=0; i<req(); i++ ) {    // For all required inputs
 160     if( i == TypeFunc::Parms ) tty->print("returns");
 161     if( in(i) ) tty->print("%c%d ", Compile::current()->node_arena()->contains(in(i)) ? ' ' : 'o', in(i)->_idx);
 162     else tty->print("_ ");
 163   }
 164 }
 165 #endif
 166 
 167 //=============================================================================
 168 RethrowNode::RethrowNode(
 169   Node* cntrl,
 170   Node* i_o,
 171   Node* memory,
 172   Node* frameptr,
 173   Node* ret_adr,
 174   Node* exception
 175 ) : Node(TypeFunc::Parms + 1) {
 176   init_req(TypeFunc::Control  , cntrl    );
 177   init_req(TypeFunc::I_O      , i_o      );
 178   init_req(TypeFunc::Memory   , memory   );
 179   init_req(TypeFunc::FramePtr , frameptr );
 180   init_req(TypeFunc::ReturnAdr, ret_adr);
 181   init_req(TypeFunc::Parms    , exception);
 182 }
 183 
 184 Node *RethrowNode::Ideal(PhaseGVN *phase, bool can_reshape){
 185   return remove_dead_region(phase, can_reshape) ? this : NULL;
 186 }
 187 
 188 const Type *RethrowNode::Value( PhaseTransform *phase ) const {
 189   return (phase->type(in(TypeFunc::Control)) == Type::TOP)
 190     ? Type::TOP
 191     : Type::BOTTOM;
 192 }
 193 
 194 uint RethrowNode::match_edge(uint idx) const {
 195   return 0;
 196 }
 197 
 198 #ifndef PRODUCT
 199 void RethrowNode::dump_req() const {
 200   // Dump the required inputs, enclosed in '(' and ')'
 201   uint i;                       // Exit value of loop
 202   for( i=0; i<req(); i++ ) {    // For all required inputs
 203     if( i == TypeFunc::Parms ) tty->print("exception");
 204     if( in(i) ) tty->print("%c%d ", Compile::current()->node_arena()->contains(in(i)) ? ' ' : 'o', in(i)->_idx);
 205     else tty->print("_ ");
 206   }
 207 }
 208 #endif
 209 
 210 //=============================================================================
 211 // Do we Match on this edge index or not?  Match only target address & method
 212 uint TailCallNode::match_edge(uint idx) const {
 213   return TypeFunc::Parms <= idx  &&  idx <= TypeFunc::Parms+1;
 214 }
 215 
 216 //=============================================================================
 217 // Do we Match on this edge index or not?  Match only target address & oop
 218 uint TailJumpNode::match_edge(uint idx) const {
 219   return TypeFunc::Parms <= idx  &&  idx <= TypeFunc::Parms+1;
 220 }
 221 
 222 //=============================================================================
 223 JVMState::JVMState(ciMethod* method, JVMState* caller) {
 224   assert(method != NULL, "must be valid call site");
 225   _method = method;
 226   debug_only(_bci = -99);  // random garbage value
 227   debug_only(_map = (SafePointNode*)-1);
 228   _caller = caller;
 229   _depth  = 1 + (caller == NULL ? 0 : caller->depth());
 230   _locoff = TypeFunc::Parms;
 231   _stkoff = _locoff + _method->max_locals();
 232   _monoff = _stkoff + _method->max_stack();
 233   _scloff = _monoff;
 234   _endoff = _monoff;
 235   _sp = 0;
 236 }
 237 JVMState::JVMState(int stack_size) {
 238   _method = NULL;
 239   _bci = InvocationEntryBci;
 240   debug_only(_map = (SafePointNode*)-1);
 241   _caller = NULL;
 242   _depth  = 1;
 243   _locoff = TypeFunc::Parms;
 244   _stkoff = _locoff;
 245   _monoff = _stkoff + stack_size;
 246   _scloff = _monoff;
 247   _endoff = _monoff;
 248   _sp = 0;
 249 }
 250 
 251 //--------------------------------of_depth-------------------------------------
 252 JVMState* JVMState::of_depth(int d) const {
 253   const JVMState* jvmp = this;
 254   assert(0 < d && (uint)d <= depth(), "oob");
 255   for (int skip = depth() - d; skip > 0; skip--) {
 256     jvmp = jvmp->caller();
 257   }
 258   assert(jvmp->depth() == (uint)d, "found the right one");
 259   return (JVMState*)jvmp;
 260 }
 261 
 262 //-----------------------------same_calls_as-----------------------------------
 263 bool JVMState::same_calls_as(const JVMState* that) const {
 264   if (this == that)                    return true;
 265   if (this->depth() != that->depth())  return false;
 266   const JVMState* p = this;
 267   const JVMState* q = that;
 268   for (;;) {
 269     if (p->_method != q->_method)    return false;
 270     if (p->_method == NULL)          return true;   // bci is irrelevant
 271     if (p->_bci    != q->_bci)       return false;
 272     p = p->caller();
 273     q = q->caller();
 274     if (p == q)                      return true;
 275     assert(p != NULL && q != NULL, "depth check ensures we don't run off end");
 276   }
 277 }
 278 
 279 //------------------------------debug_start------------------------------------
 280 uint JVMState::debug_start()  const {
 281   debug_only(JVMState* jvmroot = of_depth(1));
 282   assert(jvmroot->locoff() <= this->locoff(), "youngest JVMState must be last");
 283   return of_depth(1)->locoff();
 284 }
 285 
 286 //-------------------------------debug_end-------------------------------------
 287 uint JVMState::debug_end() const {
 288   debug_only(JVMState* jvmroot = of_depth(1));
 289   assert(jvmroot->endoff() <= this->endoff(), "youngest JVMState must be last");
 290   return endoff();
 291 }
 292 
 293 //------------------------------debug_depth------------------------------------
 294 uint JVMState::debug_depth() const {
 295   uint total = 0;
 296   for (const JVMState* jvmp = this; jvmp != NULL; jvmp = jvmp->caller()) {
 297     total += jvmp->debug_size();
 298   }
 299   return total;
 300 }
 301 
 302 #ifndef PRODUCT
 303 
 304 //------------------------------format_helper----------------------------------
 305 // Given an allocation (a Chaitin object) and a Node decide if the Node carries
 306 // any defined value or not.  If it does, print out the register or constant.
 307 static void format_helper( PhaseRegAlloc *regalloc, outputStream* st, Node *n, const char *msg, uint i, GrowableArray<SafePointScalarObjectNode*> *scobjs ) {
 308   if (n == NULL) { st->print(" NULL"); return; }
 309   if (n->is_SafePointScalarObject()) {
 310     // Scalar replacement.
 311     SafePointScalarObjectNode* spobj = n->as_SafePointScalarObject();
 312     scobjs->append_if_missing(spobj);
 313     int sco_n = scobjs->find(spobj);
 314     assert(sco_n >= 0, "");
 315     st->print(" %s%d]=#ScObj" INT32_FORMAT, msg, i, sco_n);
 316     return;
 317   }
 318   if( OptoReg::is_valid(regalloc->get_reg_first(n))) { // Check for undefined
 319     char buf[50];
 320     regalloc->dump_register(n,buf);
 321     st->print(" %s%d]=%s",msg,i,buf);
 322   } else {                      // No register, but might be constant
 323     const Type *t = n->bottom_type();
 324     switch (t->base()) {
 325     case Type::Int:
 326       st->print(" %s%d]=#"INT32_FORMAT,msg,i,t->is_int()->get_con());
 327       break;
 328     case Type::AnyPtr:
 329       assert( t == TypePtr::NULL_PTR, "" );
 330       st->print(" %s%d]=#NULL",msg,i);
 331       break;
 332     case Type::AryPtr:
 333     case Type::KlassPtr:
 334     case Type::InstPtr:
 335       st->print(" %s%d]=#Ptr" INTPTR_FORMAT,msg,i,t->isa_oopptr()->const_oop());
 336       break;
 337     case Type::NarrowOop:
 338       st->print(" %s%d]=#Ptr" INTPTR_FORMAT,msg,i,t->make_ptr()->isa_oopptr()->const_oop());
 339       break;
 340     case Type::RawPtr:
 341       st->print(" %s%d]=#Raw" INTPTR_FORMAT,msg,i,t->is_rawptr());
 342       break;
 343     case Type::DoubleCon:
 344       st->print(" %s%d]=#%fD",msg,i,t->is_double_constant()->_d);
 345       break;
 346     case Type::FloatCon:
 347       st->print(" %s%d]=#%fF",msg,i,t->is_float_constant()->_f);
 348       break;
 349     case Type::Long:
 350       st->print(" %s%d]=#"INT64_FORMAT,msg,i,t->is_long()->get_con());
 351       break;
 352     case Type::Half:
 353     case Type::Top:
 354       st->print(" %s%d]=_",msg,i);
 355       break;
 356     default: ShouldNotReachHere();
 357     }
 358   }
 359 }
 360 
 361 //------------------------------format-----------------------------------------
 362 void JVMState::format(PhaseRegAlloc *regalloc, const Node *n, outputStream* st) const {
 363   st->print("        #");
 364   if( _method ) {
 365     _method->print_short_name(st);
 366     st->print(" @ bci:%d ",_bci);
 367   } else {
 368     st->print_cr(" runtime stub ");
 369     return;
 370   }
 371   if (n->is_MachSafePoint()) {
 372     GrowableArray<SafePointScalarObjectNode*> scobjs;
 373     MachSafePointNode *mcall = n->as_MachSafePoint();
 374     uint i;
 375     // Print locals
 376     for( i = 0; i < (uint)loc_size(); i++ )
 377       format_helper( regalloc, st, mcall->local(this, i), "L[", i, &scobjs );
 378     // Print stack
 379     for (i = 0; i < (uint)stk_size(); i++) {
 380       if ((uint)(_stkoff + i) >= mcall->len())
 381         st->print(" oob ");
 382       else
 383        format_helper( regalloc, st, mcall->stack(this, i), "STK[", i, &scobjs );
 384     }
 385     for (i = 0; (int)i < nof_monitors(); i++) {
 386       Node *box = mcall->monitor_box(this, i);
 387       Node *obj = mcall->monitor_obj(this, i);
 388       if ( OptoReg::is_valid(regalloc->get_reg_first(box)) ) {
 389         while( !box->is_BoxLock() )  box = box->in(1);
 390         format_helper( regalloc, st, box, "MON-BOX[", i, &scobjs );
 391       } else {
 392         OptoReg::Name box_reg = BoxLockNode::stack_slot(box);
 393         st->print(" MON-BOX%d=%s+%d",
 394                    i,
 395                    OptoReg::regname(OptoReg::c_frame_pointer),
 396                    regalloc->reg2offset(box_reg));
 397       }
 398       const char* obj_msg = "MON-OBJ[";
 399       if (EliminateLocks) {
 400         while( !box->is_BoxLock() )  box = box->in(1);
 401         if (box->as_BoxLock()->is_eliminated())
 402           obj_msg = "MON-OBJ(LOCK ELIMINATED)[";
 403       }
 404       format_helper( regalloc, st, obj, obj_msg, i, &scobjs );
 405     }
 406 
 407     for (i = 0; i < (uint)scobjs.length(); i++) {
 408       // Scalar replaced objects.
 409       st->print_cr("");
 410       st->print("        # ScObj" INT32_FORMAT " ", i);
 411       SafePointScalarObjectNode* spobj = scobjs.at(i);
 412       ciKlass* cik = spobj->bottom_type()->is_oopptr()->klass();
 413       assert(cik->is_instance_klass() ||
 414              cik->is_array_klass(), "Not supported allocation.");
 415       ciInstanceKlass *iklass = NULL;
 416       if (cik->is_instance_klass()) {
 417         cik->print_name_on(st);
 418         iklass = cik->as_instance_klass();
 419       } else if (cik->is_type_array_klass()) {
 420         cik->as_array_klass()->base_element_type()->print_name_on(st);
 421         st->print("[%d]=", spobj->n_fields());
 422       } else if (cik->is_obj_array_klass()) {
 423         ciType* cie = cik->as_array_klass()->base_element_type();
 424         int ndim = 1;
 425         while (cie->is_obj_array_klass()) {
 426           ndim += 1;
 427           cie = cie->as_array_klass()->base_element_type();
 428         }
 429         cie->print_name_on(st);
 430         while (ndim-- > 0) {
 431           st->print("[]");
 432         }
 433         st->print("[%d]=", spobj->n_fields());
 434       }
 435       st->print("{");
 436       uint nf = spobj->n_fields();
 437       if (nf > 0) {
 438         uint first_ind = spobj->first_index();
 439         Node* fld_node = mcall->in(first_ind);
 440         ciField* cifield;
 441         if (iklass != NULL) {
 442           st->print(" [");
 443           cifield = iklass->nonstatic_field_at(0);
 444           cifield->print_name_on(st);
 445           format_helper( regalloc, st, fld_node, ":", 0, &scobjs );
 446         } else {
 447           format_helper( regalloc, st, fld_node, "[", 0, &scobjs );
 448         }
 449         for (uint j = 1; j < nf; j++) {
 450           fld_node = mcall->in(first_ind+j);
 451           if (iklass != NULL) {
 452             st->print(", [");
 453             cifield = iklass->nonstatic_field_at(j);
 454             cifield->print_name_on(st);
 455             format_helper( regalloc, st, fld_node, ":", j, &scobjs );
 456           } else {
 457             format_helper( regalloc, st, fld_node, ", [", j, &scobjs );
 458           }
 459         }
 460       }
 461       st->print(" }");
 462     }
 463   }
 464   st->print_cr("");
 465   if (caller() != NULL)  caller()->format(regalloc, n, st);
 466 }
 467 
 468 
 469 void JVMState::dump_spec(outputStream *st) const {
 470   if (_method != NULL) {
 471     bool printed = false;
 472     if (!Verbose) {
 473       // The JVMS dumps make really, really long lines.
 474       // Take out the most boring parts, which are the package prefixes.
 475       char buf[500];
 476       stringStream namest(buf, sizeof(buf));
 477       _method->print_short_name(&namest);
 478       if (namest.count() < sizeof(buf)) {
 479         const char* name = namest.base();
 480         if (name[0] == ' ')  ++name;
 481         const char* endcn = strchr(name, ':');  // end of class name
 482         if (endcn == NULL)  endcn = strchr(name, '(');
 483         if (endcn == NULL)  endcn = name + strlen(name);
 484         while (endcn > name && endcn[-1] != '.' && endcn[-1] != '/')
 485           --endcn;
 486         st->print(" %s", endcn);
 487         printed = true;
 488       }
 489     }
 490     if (!printed)
 491       _method->print_short_name(st);
 492     st->print(" @ bci:%d",_bci);
 493   } else {
 494     st->print(" runtime stub");
 495   }
 496   if (caller() != NULL)  caller()->dump_spec(st);
 497 }
 498 
 499 
 500 void JVMState::dump_on(outputStream* st) const {
 501   if (_map && !((uintptr_t)_map & 1)) {
 502     if (_map->len() > _map->req()) {  // _map->has_exceptions()
 503       Node* ex = _map->in(_map->req());  // _map->next_exception()
 504       // skip the first one; it's already being printed
 505       while (ex != NULL && ex->len() > ex->req()) {
 506         ex = ex->in(ex->req());  // ex->next_exception()
 507         ex->dump(1);
 508       }
 509     }
 510     _map->dump(2);
 511   }
 512   st->print("JVMS depth=%d loc=%d stk=%d mon=%d scalar=%d end=%d mondepth=%d sp=%d bci=%d method=",
 513              depth(), locoff(), stkoff(), monoff(), scloff(), endoff(), monitor_depth(), sp(), bci());
 514   if (_method == NULL) {
 515     st->print_cr("(none)");
 516   } else {
 517     _method->print_name(st);
 518     st->cr();
 519     if (bci() >= 0 && bci() < _method->code_size()) {
 520       st->print("    bc: ");
 521       _method->print_codes_on(bci(), bci()+1, st);
 522     }
 523   }
 524   if (caller() != NULL) {
 525     caller()->dump_on(st);
 526   }
 527 }
 528 
 529 // Extra way to dump a jvms from the debugger,
 530 // to avoid a bug with C++ member function calls.
 531 void dump_jvms(JVMState* jvms) {
 532   jvms->dump();
 533 }
 534 #endif
 535 
 536 //--------------------------clone_shallow--------------------------------------
 537 JVMState* JVMState::clone_shallow(Compile* C) const {
 538   JVMState* n = has_method() ? new (C) JVMState(_method, _caller) : new (C) JVMState(0);
 539   n->set_bci(_bci);
 540   n->set_locoff(_locoff);
 541   n->set_stkoff(_stkoff);
 542   n->set_monoff(_monoff);
 543   n->set_scloff(_scloff);
 544   n->set_endoff(_endoff);
 545   n->set_sp(_sp);
 546   n->set_map(_map);
 547   return n;
 548 }
 549 
 550 //---------------------------clone_deep----------------------------------------
 551 JVMState* JVMState::clone_deep(Compile* C) const {
 552   JVMState* n = clone_shallow(C);
 553   for (JVMState* p = n; p->_caller != NULL; p = p->_caller) {
 554     p->_caller = p->_caller->clone_shallow(C);
 555   }
 556   assert(n->depth() == depth(), "sanity");
 557   assert(n->debug_depth() == debug_depth(), "sanity");
 558   return n;
 559 }
 560 
 561 //=============================================================================
 562 uint CallNode::cmp( const Node &n ) const
 563 { return _tf == ((CallNode&)n)._tf && _jvms == ((CallNode&)n)._jvms; }
 564 #ifndef PRODUCT
 565 void CallNode::dump_req() const {
 566   // Dump the required inputs, enclosed in '(' and ')'
 567   uint i;                       // Exit value of loop
 568   for( i=0; i<req(); i++ ) {    // For all required inputs
 569     if( i == TypeFunc::Parms ) tty->print("(");
 570     if( in(i) ) tty->print("%c%d ", Compile::current()->node_arena()->contains(in(i)) ? ' ' : 'o', in(i)->_idx);
 571     else tty->print("_ ");
 572   }
 573   tty->print(")");
 574 }
 575 
 576 void CallNode::dump_spec(outputStream *st) const {
 577   st->print(" ");
 578   tf()->dump_on(st);
 579   if (_cnt != COUNT_UNKNOWN)  st->print(" C=%f",_cnt);
 580   if (jvms() != NULL)  jvms()->dump_spec(st);
 581 }
 582 #endif
 583 
 584 const Type *CallNode::bottom_type() const { return tf()->range(); }
 585 const Type *CallNode::Value(PhaseTransform *phase) const {
 586   if (phase->type(in(0)) == Type::TOP)  return Type::TOP;
 587   return tf()->range();
 588 }
 589 
 590 //------------------------------calling_convention-----------------------------
 591 void CallNode::calling_convention( BasicType* sig_bt, VMRegPair *parm_regs, uint argcnt ) const {
 592   // Use the standard compiler calling convention
 593   Matcher::calling_convention( sig_bt, parm_regs, argcnt, true );
 594 }
 595 
 596 
 597 //------------------------------match------------------------------------------
 598 // Construct projections for control, I/O, memory-fields, ..., and
 599 // return result(s) along with their RegMask info
 600 Node *CallNode::match( const ProjNode *proj, const Matcher *match ) {
 601   switch (proj->_con) {
 602   case TypeFunc::Control:
 603   case TypeFunc::I_O:
 604   case TypeFunc::Memory:
 605     return new (match->C, 1) MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj);
 606 
 607   case TypeFunc::Parms+1:       // For LONG & DOUBLE returns
 608     assert(tf()->_range->field_at(TypeFunc::Parms+1) == Type::HALF, "");
 609     // 2nd half of doubles and longs
 610     return new (match->C, 1) MachProjNode(this,proj->_con, RegMask::Empty, (uint)OptoReg::Bad);
 611 
 612   case TypeFunc::Parms: {       // Normal returns
 613     uint ideal_reg = Matcher::base2reg[tf()->range()->field_at(TypeFunc::Parms)->base()];
 614     OptoRegPair regs = is_CallRuntime()
 615       ? match->c_return_value(ideal_reg,true)  // Calls into C runtime
 616       : match->  return_value(ideal_reg,true); // Calls into compiled Java code
 617     RegMask rm = RegMask(regs.first());
 618     if( OptoReg::is_valid(regs.second()) )
 619       rm.Insert( regs.second() );
 620     return new (match->C, 1) MachProjNode(this,proj->_con,rm,ideal_reg);
 621   }
 622 
 623   case TypeFunc::ReturnAdr:
 624   case TypeFunc::FramePtr:
 625   default:
 626     ShouldNotReachHere();
 627   }
 628   return NULL;
 629 }
 630 
 631 // Do we Match on this edge index or not?  Match no edges
 632 uint CallNode::match_edge(uint idx) const {
 633   return 0;
 634 }
 635 
 636 //
 637 // Determine whether the call could modify the field of the specified
 638 // instance at the specified offset.
 639 //
 640 bool CallNode::may_modify(const TypePtr *addr_t, PhaseTransform *phase) {
 641   const TypeOopPtr *adrInst_t  = addr_t->isa_oopptr();
 642 
 643   // If not an OopPtr or not an instance type, assume the worst.
 644   // Note: currently this method is called only for instance types.
 645   if (adrInst_t == NULL || !adrInst_t->is_known_instance()) {
 646     return true;
 647   }
 648   // The instance_id is set only for scalar-replaceable allocations which
 649   // are not passed as arguments according to Escape Analysis.
 650   return false;
 651 }
 652 
 653 // Does this call have a direct reference to n other than debug information?
 654 bool CallNode::has_non_debug_use(Node *n) {
 655   const TypeTuple * d = tf()->domain();
 656   for (uint i = TypeFunc::Parms; i < d->cnt(); i++) {
 657     Node *arg = in(i);
 658     if (arg == n) {
 659       return true;
 660     }
 661   }
 662   return false;
 663 }
 664 
 665 // Returns the unique CheckCastPP of a call
 666 // or 'this' if there are several CheckCastPP
 667 // or returns NULL if there is no one.
 668 Node *CallNode::result_cast() {
 669   Node *cast = NULL;
 670 
 671   Node *p = proj_out(TypeFunc::Parms);
 672   if (p == NULL)
 673     return NULL;
 674 
 675   for (DUIterator_Fast imax, i = p->fast_outs(imax); i < imax; i++) {
 676     Node *use = p->fast_out(i);
 677     if (use->is_CheckCastPP()) {
 678       if (cast != NULL) {
 679         return this;  // more than 1 CheckCastPP
 680       }
 681       cast = use;
 682     }
 683   }
 684   return cast;
 685 }
 686 
 687 
 688 //=============================================================================
 689 uint CallJavaNode::size_of() const { return sizeof(*this); }
 690 uint CallJavaNode::cmp( const Node &n ) const {
 691   CallJavaNode &call = (CallJavaNode&)n;
 692   return CallNode::cmp(call) && _method == call._method;
 693 }
 694 #ifndef PRODUCT
 695 void CallJavaNode::dump_spec(outputStream *st) const {
 696   if( _method ) _method->print_short_name(st);
 697   CallNode::dump_spec(st);
 698 }
 699 #endif
 700 
 701 //=============================================================================
 702 uint CallStaticJavaNode::size_of() const { return sizeof(*this); }
 703 uint CallStaticJavaNode::cmp( const Node &n ) const {
 704   CallStaticJavaNode &call = (CallStaticJavaNode&)n;
 705   return CallJavaNode::cmp(call);
 706 }
 707 
 708 //----------------------------uncommon_trap_request----------------------------
 709 // If this is an uncommon trap, return the request code, else zero.
 710 int CallStaticJavaNode::uncommon_trap_request() const {
 711   if (_name != NULL && !strcmp(_name, "uncommon_trap")) {
 712     return extract_uncommon_trap_request(this);
 713   }
 714   return 0;
 715 }
 716 int CallStaticJavaNode::extract_uncommon_trap_request(const Node* call) {
 717 #ifndef PRODUCT
 718   if (!(call->req() > TypeFunc::Parms &&
 719         call->in(TypeFunc::Parms) != NULL &&
 720         call->in(TypeFunc::Parms)->is_Con())) {
 721     assert(_in_dump_cnt != 0, "OK if dumping");
 722     tty->print("[bad uncommon trap]");
 723     return 0;
 724   }
 725 #endif
 726   return call->in(TypeFunc::Parms)->bottom_type()->is_int()->get_con();
 727 }
 728 
 729 #ifndef PRODUCT
 730 void CallStaticJavaNode::dump_spec(outputStream *st) const {
 731   st->print("# Static ");
 732   if (_name != NULL) {
 733     st->print("%s", _name);
 734     int trap_req = uncommon_trap_request();
 735     if (trap_req != 0) {
 736       char buf[100];
 737       st->print("(%s)",
 738                  Deoptimization::format_trap_request(buf, sizeof(buf),
 739                                                      trap_req));
 740     }
 741     st->print(" ");
 742   }
 743   CallJavaNode::dump_spec(st);
 744 }
 745 #endif
 746 
 747 //=============================================================================
 748 uint CallDynamicJavaNode::size_of() const { return sizeof(*this); }
 749 uint CallDynamicJavaNode::cmp( const Node &n ) const {
 750   CallDynamicJavaNode &call = (CallDynamicJavaNode&)n;
 751   return CallJavaNode::cmp(call);
 752 }
 753 #ifndef PRODUCT
 754 void CallDynamicJavaNode::dump_spec(outputStream *st) const {
 755   st->print("# Dynamic ");
 756   CallJavaNode::dump_spec(st);
 757 }
 758 #endif
 759 
 760 //=============================================================================
 761 uint CallRuntimeNode::size_of() const { return sizeof(*this); }
 762 uint CallRuntimeNode::cmp( const Node &n ) const {
 763   CallRuntimeNode &call = (CallRuntimeNode&)n;
 764   return CallNode::cmp(call) && !strcmp(_name,call._name);
 765 }
 766 #ifndef PRODUCT
 767 void CallRuntimeNode::dump_spec(outputStream *st) const {
 768   st->print("# ");
 769   st->print(_name);
 770   CallNode::dump_spec(st);
 771 }
 772 #endif
 773 
 774 //------------------------------calling_convention-----------------------------
 775 void CallRuntimeNode::calling_convention( BasicType* sig_bt, VMRegPair *parm_regs, uint argcnt ) const {
 776   Matcher::c_calling_convention( sig_bt, parm_regs, argcnt );
 777 }
 778 
 779 //=============================================================================
 780 //------------------------------calling_convention-----------------------------
 781 
 782 
 783 //=============================================================================
 784 #ifndef PRODUCT
 785 void CallLeafNode::dump_spec(outputStream *st) const {
 786   st->print("# ");
 787   st->print(_name);
 788   CallNode::dump_spec(st);
 789 }
 790 #endif
 791 
 792 //=============================================================================
 793 
 794 void SafePointNode::set_local(JVMState* jvms, uint idx, Node *c) {
 795   assert(verify_jvms(jvms), "jvms must match");
 796   int loc = jvms->locoff() + idx;
 797   if (in(loc)->is_top() && idx > 0 && !c->is_top() ) {
 798     // If current local idx is top then local idx - 1 could
 799     // be a long/double that needs to be killed since top could
 800     // represent the 2nd half ofthe long/double.
 801     uint ideal = in(loc -1)->ideal_reg();
 802     if (ideal == Op_RegD || ideal == Op_RegL) {
 803       // set other (low index) half to top
 804       set_req(loc - 1, in(loc));
 805     }
 806   }
 807   set_req(loc, c);
 808 }
 809 
 810 uint SafePointNode::size_of() const { return sizeof(*this); }
 811 uint SafePointNode::cmp( const Node &n ) const {
 812   return (&n == this);          // Always fail except on self
 813 }
 814 
 815 //-------------------------set_next_exception----------------------------------
 816 void SafePointNode::set_next_exception(SafePointNode* n) {
 817   assert(n == NULL || n->Opcode() == Op_SafePoint, "correct value for next_exception");
 818   if (len() == req()) {
 819     if (n != NULL)  add_prec(n);
 820   } else {
 821     set_prec(req(), n);
 822   }
 823 }
 824 
 825 
 826 //----------------------------next_exception-----------------------------------
 827 SafePointNode* SafePointNode::next_exception() const {
 828   if (len() == req()) {
 829     return NULL;
 830   } else {
 831     Node* n = in(req());
 832     assert(n == NULL || n->Opcode() == Op_SafePoint, "no other uses of prec edges");
 833     return (SafePointNode*) n;
 834   }
 835 }
 836 
 837 
 838 //------------------------------Ideal------------------------------------------
 839 // Skip over any collapsed Regions
 840 Node *SafePointNode::Ideal(PhaseGVN *phase, bool can_reshape) {
 841   return remove_dead_region(phase, can_reshape) ? this : NULL;
 842 }
 843 
 844 //------------------------------Identity---------------------------------------
 845 // Remove obviously duplicate safepoints
 846 Node *SafePointNode::Identity( PhaseTransform *phase ) {
 847 
 848   // If you have back to back safepoints, remove one
 849   if( in(TypeFunc::Control)->is_SafePoint() )
 850     return in(TypeFunc::Control);
 851 
 852   if( in(0)->is_Proj() ) {
 853     Node *n0 = in(0)->in(0);
 854     // Check if he is a call projection (except Leaf Call)
 855     if( n0->is_Catch() ) {
 856       n0 = n0->in(0)->in(0);
 857       assert( n0->is_Call(), "expect a call here" );
 858     }
 859     if( n0->is_Call() && n0->as_Call()->guaranteed_safepoint() ) {
 860       // Useless Safepoint, so remove it
 861       return in(TypeFunc::Control);
 862     }
 863   }
 864 
 865   return this;
 866 }
 867 
 868 //------------------------------Value------------------------------------------
 869 const Type *SafePointNode::Value( PhaseTransform *phase ) const {
 870   if( phase->type(in(0)) == Type::TOP ) return Type::TOP;
 871   if( phase->eqv( in(0), this ) ) return Type::TOP; // Dead infinite loop
 872   return Type::CONTROL;
 873 }
 874 
 875 #ifndef PRODUCT
 876 void SafePointNode::dump_spec(outputStream *st) const {
 877   st->print(" SafePoint ");
 878 }
 879 #endif
 880 
 881 const RegMask &SafePointNode::in_RegMask(uint idx) const {
 882   if( idx < TypeFunc::Parms ) return RegMask::Empty;
 883   // Values outside the domain represent debug info
 884   return *(Compile::current()->matcher()->idealreg2debugmask[in(idx)->ideal_reg()]);
 885 }
 886 const RegMask &SafePointNode::out_RegMask() const {
 887   return RegMask::Empty;
 888 }
 889 
 890 
 891 void SafePointNode::grow_stack(JVMState* jvms, uint grow_by) {
 892   assert((int)grow_by > 0, "sanity");
 893   int monoff = jvms->monoff();
 894   int scloff = jvms->scloff();
 895   int endoff = jvms->endoff();
 896   assert(endoff == (int)req(), "no other states or debug info after me");
 897   Node* top = Compile::current()->top();
 898   for (uint i = 0; i < grow_by; i++) {
 899     ins_req(monoff, top);
 900   }
 901   jvms->set_monoff(monoff + grow_by);
 902   jvms->set_scloff(scloff + grow_by);
 903   jvms->set_endoff(endoff + grow_by);
 904 }
 905 
 906 void SafePointNode::push_monitor(const FastLockNode *lock) {
 907   // Add a LockNode, which points to both the original BoxLockNode (the
 908   // stack space for the monitor) and the Object being locked.
 909   const int MonitorEdges = 2;
 910   assert(JVMState::logMonitorEdges == exact_log2(MonitorEdges), "correct MonitorEdges");
 911   assert(req() == jvms()->endoff(), "correct sizing");
 912   int nextmon = jvms()->scloff();
 913   if (GenerateSynchronizationCode) {
 914     add_req(lock->box_node());
 915     add_req(lock->obj_node());
 916   } else {
 917     Node* top = Compile::current()->top();
 918     add_req(top);
 919     add_req(top);
 920   }
 921   jvms()->set_scloff(nextmon+MonitorEdges);
 922   jvms()->set_endoff(req());
 923 }
 924 
 925 void SafePointNode::pop_monitor() {
 926   // Delete last monitor from debug info
 927   debug_only(int num_before_pop = jvms()->nof_monitors());
 928   const int MonitorEdges = (1<<JVMState::logMonitorEdges);
 929   int scloff = jvms()->scloff();
 930   int endoff = jvms()->endoff();
 931   int new_scloff = scloff - MonitorEdges;
 932   int new_endoff = endoff - MonitorEdges;
 933   jvms()->set_scloff(new_scloff);
 934   jvms()->set_endoff(new_endoff);
 935   while (scloff > new_scloff)  del_req(--scloff);
 936   assert(jvms()->nof_monitors() == num_before_pop-1, "");
 937 }
 938 
 939 Node *SafePointNode::peek_monitor_box() const {
 940   int mon = jvms()->nof_monitors() - 1;
 941   assert(mon >= 0, "most have a monitor");
 942   return monitor_box(jvms(), mon);
 943 }
 944 
 945 Node *SafePointNode::peek_monitor_obj() const {
 946   int mon = jvms()->nof_monitors() - 1;
 947   assert(mon >= 0, "most have a monitor");
 948   return monitor_obj(jvms(), mon);
 949 }
 950 
 951 // Do we Match on this edge index or not?  Match no edges
 952 uint SafePointNode::match_edge(uint idx) const {
 953   if( !needs_polling_address_input() )
 954     return 0;
 955 
 956   return (TypeFunc::Parms == idx);
 957 }
 958 
 959 //==============  SafePointScalarObjectNode  ==============
 960 
 961 SafePointScalarObjectNode::SafePointScalarObjectNode(const TypeOopPtr* tp,
 962 #ifdef ASSERT
 963                                                      AllocateNode* alloc,
 964 #endif
 965                                                      uint first_index,
 966                                                      uint n_fields) :
 967   TypeNode(tp, 1), // 1 control input -- seems required.  Get from root.
 968 #ifdef ASSERT
 969   _alloc(alloc),
 970 #endif
 971   _first_index(first_index),
 972   _n_fields(n_fields)
 973 {
 974   init_class_id(Class_SafePointScalarObject);
 975 }
 976 
 977 bool SafePointScalarObjectNode::pinned() const { return true; }
 978 bool SafePointScalarObjectNode::depends_only_on_test() const { return false; }
 979 
 980 uint SafePointScalarObjectNode::ideal_reg() const {
 981   return 0; // No matching to machine instruction
 982 }
 983 
 984 const RegMask &SafePointScalarObjectNode::in_RegMask(uint idx) const {
 985   return *(Compile::current()->matcher()->idealreg2debugmask[in(idx)->ideal_reg()]);
 986 }
 987 
 988 const RegMask &SafePointScalarObjectNode::out_RegMask() const {
 989   return RegMask::Empty;
 990 }
 991 
 992 uint SafePointScalarObjectNode::match_edge(uint idx) const {
 993   return 0;
 994 }
 995 
 996 SafePointScalarObjectNode*
 997 SafePointScalarObjectNode::clone(int jvms_adj, Dict* sosn_map) const {
 998   void* cached = (*sosn_map)[(void*)this];
 999   if (cached != NULL) {
1000     return (SafePointScalarObjectNode*)cached;
1001   }
1002   Compile* C = Compile::current();
1003   SafePointScalarObjectNode* res = (SafePointScalarObjectNode*)Node::clone();
1004   res->_first_index += jvms_adj;
1005   sosn_map->Insert((void*)this, (void*)res);
1006   return res;
1007 }
1008 
1009 
1010 #ifndef PRODUCT
1011 void SafePointScalarObjectNode::dump_spec(outputStream *st) const {
1012   st->print(" # fields@[%d..%d]", first_index(),
1013              first_index() + n_fields() - 1);
1014 }
1015 
1016 #endif
1017 
1018 //=============================================================================
1019 uint AllocateNode::size_of() const { return sizeof(*this); }
1020 
1021 AllocateNode::AllocateNode(Compile* C, const TypeFunc *atype,
1022                            Node *ctrl, Node *mem, Node *abio,
1023                            Node *size, Node *klass_node, Node *initial_test)
1024   : CallNode(atype, NULL, TypeRawPtr::BOTTOM)
1025 {
1026   init_class_id(Class_Allocate);
1027   init_flags(Flag_is_macro);
1028   _is_scalar_replaceable = false;
1029   Node *topnode = C->top();
1030 
1031   init_req( TypeFunc::Control  , ctrl );
1032   init_req( TypeFunc::I_O      , abio );
1033   init_req( TypeFunc::Memory   , mem );
1034   init_req( TypeFunc::ReturnAdr, topnode );
1035   init_req( TypeFunc::FramePtr , topnode );
1036   init_req( AllocSize          , size);
1037   init_req( KlassNode          , klass_node);
1038   init_req( InitialTest        , initial_test);
1039   init_req( ALength            , topnode);
1040   C->add_macro_node(this);
1041 }
1042 
1043 //=============================================================================
1044 uint AllocateArrayNode::size_of() const { return sizeof(*this); }
1045 
1046 Node* AllocateArrayNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1047   if (remove_dead_region(phase, can_reshape))  return this;
1048 
1049   const Type* type = phase->type(Ideal_length());
1050   if (type->isa_int() && type->is_int()->_hi < 0) {
1051     if (can_reshape) {
1052       PhaseIterGVN *igvn = phase->is_IterGVN();
1053       // Unreachable fall through path (negative array length),
1054       // the allocation can only throw so disconnect it.
1055       Node* proj = proj_out(TypeFunc::Control);
1056       Node* catchproj = NULL;
1057       if (proj != NULL) {
1058         for (DUIterator_Fast imax, i = proj->fast_outs(imax); i < imax; i++) {
1059           Node *cn = proj->fast_out(i);
1060           if (cn->is_Catch()) {
1061             catchproj = cn->as_Multi()->proj_out(CatchProjNode::fall_through_index);
1062             break;
1063           }
1064         }
1065       }
1066       if (catchproj != NULL && catchproj->outcnt() > 0 &&
1067           (catchproj->outcnt() > 1 ||
1068            catchproj->unique_out()->Opcode() != Op_Halt)) {
1069         assert(catchproj->is_CatchProj(), "must be a CatchProjNode");
1070         Node* nproj = catchproj->clone();
1071         igvn->register_new_node_with_optimizer(nproj);
1072 
1073         Node *frame = new (phase->C, 1) ParmNode( phase->C->start(), TypeFunc::FramePtr );
1074         frame = phase->transform(frame);
1075         // Halt & Catch Fire
1076         Node *halt = new (phase->C, TypeFunc::Parms) HaltNode( nproj, frame );
1077         phase->C->root()->add_req(halt);
1078         phase->transform(halt);
1079 
1080         igvn->replace_node(catchproj, phase->C->top());
1081         return this;
1082       }
1083     } else {
1084       // Can't correct it during regular GVN so register for IGVN
1085       phase->C->record_for_igvn(this);
1086     }
1087   }
1088   return NULL;
1089 }
1090 
1091 // Retrieve the length from the AllocateArrayNode. Narrow the type with a
1092 // CastII, if appropriate.  If we are not allowed to create new nodes, and
1093 // a CastII is appropriate, return NULL.
1094 Node *AllocateArrayNode::make_ideal_length(const TypeOopPtr* oop_type, PhaseTransform *phase, bool allow_new_nodes) {
1095   Node *length = in(AllocateNode::ALength);
1096   assert(length != NULL, "length is not null");
1097 
1098   const TypeInt* length_type = phase->find_int_type(length);
1099   const TypeAryPtr* ary_type = oop_type->isa_aryptr();
1100 
1101   if (ary_type != NULL && length_type != NULL) {
1102     const TypeInt* narrow_length_type = ary_type->narrow_size_type(length_type);
1103     if (narrow_length_type != length_type) {
1104       // Assert one of:
1105       //   - the narrow_length is 0
1106       //   - the narrow_length is not wider than length
1107       assert(narrow_length_type == TypeInt::ZERO ||
1108              (narrow_length_type->_hi <= length_type->_hi &&
1109               narrow_length_type->_lo >= length_type->_lo),
1110              "narrow type must be narrower than length type");
1111 
1112       // Return NULL if new nodes are not allowed
1113       if (!allow_new_nodes) return NULL;
1114       // Create a cast which is control dependent on the initialization to
1115       // propagate the fact that the array length must be positive.
1116       length = new (phase->C, 2) CastIINode(length, narrow_length_type);
1117       length->set_req(0, initialization()->proj_out(0));
1118     }
1119   }
1120 
1121   return length;
1122 }
1123 
1124 //=============================================================================
1125 uint LockNode::size_of() const { return sizeof(*this); }
1126 
1127 // Redundant lock elimination
1128 //
1129 // There are various patterns of locking where we release and
1130 // immediately reacquire a lock in a piece of code where no operations
1131 // occur in between that would be observable.  In those cases we can
1132 // skip releasing and reacquiring the lock without violating any
1133 // fairness requirements.  Doing this around a loop could cause a lock
1134 // to be held for a very long time so we concentrate on non-looping
1135 // control flow.  We also require that the operations are fully
1136 // redundant meaning that we don't introduce new lock operations on
1137 // some paths so to be able to eliminate it on others ala PRE.  This
1138 // would probably require some more extensive graph manipulation to
1139 // guarantee that the memory edges were all handled correctly.
1140 //
1141 // Assuming p is a simple predicate which can't trap in any way and s
1142 // is a synchronized method consider this code:
1143 //
1144 //   s();
1145 //   if (p)
1146 //     s();
1147 //   else
1148 //     s();
1149 //   s();
1150 //
1151 // 1. The unlocks of the first call to s can be eliminated if the
1152 // locks inside the then and else branches are eliminated.
1153 //
1154 // 2. The unlocks of the then and else branches can be eliminated if
1155 // the lock of the final call to s is eliminated.
1156 //
1157 // Either of these cases subsumes the simple case of sequential control flow
1158 //
1159 // Addtionally we can eliminate versions without the else case:
1160 //
1161 //   s();
1162 //   if (p)
1163 //     s();
1164 //   s();
1165 //
1166 // 3. In this case we eliminate the unlock of the first s, the lock
1167 // and unlock in the then case and the lock in the final s.
1168 //
1169 // Note also that in all these cases the then/else pieces don't have
1170 // to be trivial as long as they begin and end with synchronization
1171 // operations.
1172 //
1173 //   s();
1174 //   if (p)
1175 //     s();
1176 //     f();
1177 //     s();
1178 //   s();
1179 //
1180 // The code will work properly for this case, leaving in the unlock
1181 // before the call to f and the relock after it.
1182 //
1183 // A potentially interesting case which isn't handled here is when the
1184 // locking is partially redundant.
1185 //
1186 //   s();
1187 //   if (p)
1188 //     s();
1189 //
1190 // This could be eliminated putting unlocking on the else case and
1191 // eliminating the first unlock and the lock in the then side.
1192 // Alternatively the unlock could be moved out of the then side so it
1193 // was after the merge and the first unlock and second lock
1194 // eliminated.  This might require less manipulation of the memory
1195 // state to get correct.
1196 //
1197 // Additionally we might allow work between a unlock and lock before
1198 // giving up eliminating the locks.  The current code disallows any
1199 // conditional control flow between these operations.  A formulation
1200 // similar to partial redundancy elimination computing the
1201 // availability of unlocking and the anticipatability of locking at a
1202 // program point would allow detection of fully redundant locking with
1203 // some amount of work in between.  I'm not sure how often I really
1204 // think that would occur though.  Most of the cases I've seen
1205 // indicate it's likely non-trivial work would occur in between.
1206 // There may be other more complicated constructs where we could
1207 // eliminate locking but I haven't seen any others appear as hot or
1208 // interesting.
1209 //
1210 // Locking and unlocking have a canonical form in ideal that looks
1211 // roughly like this:
1212 //
1213 //              <obj>
1214 //                | \\------+
1215 //                |  \       \
1216 //                | BoxLock   \
1217 //                |  |   |     \
1218 //                |  |    \     \
1219 //                |  |   FastLock
1220 //                |  |   /
1221 //                |  |  /
1222 //                |  |  |
1223 //
1224 //               Lock
1225 //                |
1226 //            Proj #0
1227 //                |
1228 //            MembarAcquire
1229 //                |
1230 //            Proj #0
1231 //
1232 //            MembarRelease
1233 //                |
1234 //            Proj #0
1235 //                |
1236 //              Unlock
1237 //                |
1238 //            Proj #0
1239 //
1240 //
1241 // This code proceeds by processing Lock nodes during PhaseIterGVN
1242 // and searching back through its control for the proper code
1243 // patterns.  Once it finds a set of lock and unlock operations to
1244 // eliminate they are marked as eliminatable which causes the
1245 // expansion of the Lock and Unlock macro nodes to make the operation a NOP
1246 //
1247 //=============================================================================
1248 
1249 //
1250 // Utility function to skip over uninteresting control nodes.  Nodes skipped are:
1251 //   - copy regions.  (These may not have been optimized away yet.)
1252 //   - eliminated locking nodes
1253 //
1254 static Node *next_control(Node *ctrl) {
1255   if (ctrl == NULL)
1256     return NULL;
1257   while (1) {
1258     if (ctrl->is_Region()) {
1259       RegionNode *r = ctrl->as_Region();
1260       Node *n = r->is_copy();
1261       if (n == NULL)
1262         break;  // hit a region, return it
1263       else
1264         ctrl = n;
1265     } else if (ctrl->is_Proj()) {
1266       Node *in0 = ctrl->in(0);
1267       if (in0->is_AbstractLock() && in0->as_AbstractLock()->is_eliminated()) {
1268         ctrl = in0->in(0);
1269       } else {
1270         break;
1271       }
1272     } else {
1273       break; // found an interesting control
1274     }
1275   }
1276   return ctrl;
1277 }
1278 //
1279 // Given a control, see if it's the control projection of an Unlock which
1280 // operating on the same object as lock.
1281 //
1282 bool AbstractLockNode::find_matching_unlock(const Node* ctrl, LockNode* lock,
1283                                             GrowableArray<AbstractLockNode*> &lock_ops) {
1284   ProjNode *ctrl_proj = (ctrl->is_Proj()) ? ctrl->as_Proj() : NULL;
1285   if (ctrl_proj != NULL && ctrl_proj->_con == TypeFunc::Control) {
1286     Node *n = ctrl_proj->in(0);
1287     if (n != NULL && n->is_Unlock()) {
1288       UnlockNode *unlock = n->as_Unlock();
1289       if ((lock->obj_node() == unlock->obj_node()) &&
1290           (lock->box_node() == unlock->box_node()) && !unlock->is_eliminated()) {
1291         lock_ops.append(unlock);
1292         return true;
1293       }
1294     }
1295   }
1296   return false;
1297 }
1298 
1299 //
1300 // Find the lock matching an unlock.  Returns null if a safepoint
1301 // or complicated control is encountered first.
1302 LockNode *AbstractLockNode::find_matching_lock(UnlockNode* unlock) {
1303   LockNode *lock_result = NULL;
1304   // find the matching lock, or an intervening safepoint
1305   Node *ctrl = next_control(unlock->in(0));
1306   while (1) {
1307     assert(ctrl != NULL, "invalid control graph");
1308     assert(!ctrl->is_Start(), "missing lock for unlock");
1309     if (ctrl->is_top()) break;  // dead control path
1310     if (ctrl->is_Proj()) ctrl = ctrl->in(0);
1311     if (ctrl->is_SafePoint()) {
1312         break;  // found a safepoint (may be the lock we are searching for)
1313     } else if (ctrl->is_Region()) {
1314       // Check for a simple diamond pattern.  Punt on anything more complicated
1315       if (ctrl->req() == 3 && ctrl->in(1) != NULL && ctrl->in(2) != NULL) {
1316         Node *in1 = next_control(ctrl->in(1));
1317         Node *in2 = next_control(ctrl->in(2));
1318         if (((in1->is_IfTrue() && in2->is_IfFalse()) ||
1319              (in2->is_IfTrue() && in1->is_IfFalse())) && (in1->in(0) == in2->in(0))) {
1320           ctrl = next_control(in1->in(0)->in(0));
1321         } else {
1322           break;
1323         }
1324       } else {
1325         break;
1326       }
1327     } else {
1328       ctrl = next_control(ctrl->in(0));  // keep searching
1329     }
1330   }
1331   if (ctrl->is_Lock()) {
1332     LockNode *lock = ctrl->as_Lock();
1333     if ((lock->obj_node() == unlock->obj_node()) &&
1334             (lock->box_node() == unlock->box_node())) {
1335       lock_result = lock;
1336     }
1337   }
1338   return lock_result;
1339 }
1340 
1341 // This code corresponds to case 3 above.
1342 
1343 bool AbstractLockNode::find_lock_and_unlock_through_if(Node* node, LockNode* lock,
1344                                                        GrowableArray<AbstractLockNode*> &lock_ops) {
1345   Node* if_node = node->in(0);
1346   bool  if_true = node->is_IfTrue();
1347 
1348   if (if_node->is_If() && if_node->outcnt() == 2 && (if_true || node->is_IfFalse())) {
1349     Node *lock_ctrl = next_control(if_node->in(0));
1350     if (find_matching_unlock(lock_ctrl, lock, lock_ops)) {
1351       Node* lock1_node = NULL;
1352       ProjNode* proj = if_node->as_If()->proj_out(!if_true);
1353       if (if_true) {
1354         if (proj->is_IfFalse() && proj->outcnt() == 1) {
1355           lock1_node = proj->unique_out();
1356         }
1357       } else {
1358         if (proj->is_IfTrue() && proj->outcnt() == 1) {
1359           lock1_node = proj->unique_out();
1360         }
1361       }
1362       if (lock1_node != NULL && lock1_node->is_Lock()) {
1363         LockNode *lock1 = lock1_node->as_Lock();
1364         if ((lock->obj_node() == lock1->obj_node()) &&
1365             (lock->box_node() == lock1->box_node()) && !lock1->is_eliminated()) {
1366           lock_ops.append(lock1);
1367           return true;
1368         }
1369       }
1370     }
1371   }
1372 
1373   lock_ops.trunc_to(0);
1374   return false;
1375 }
1376 
1377 bool AbstractLockNode::find_unlocks_for_region(const RegionNode* region, LockNode* lock,
1378                                GrowableArray<AbstractLockNode*> &lock_ops) {
1379   // check each control merging at this point for a matching unlock.
1380   // in(0) should be self edge so skip it.
1381   for (int i = 1; i < (int)region->req(); i++) {
1382     Node *in_node = next_control(region->in(i));
1383     if (in_node != NULL) {
1384       if (find_matching_unlock(in_node, lock, lock_ops)) {
1385         // found a match so keep on checking.
1386         continue;
1387       } else if (find_lock_and_unlock_through_if(in_node, lock, lock_ops)) {
1388         continue;
1389       }
1390 
1391       // If we fall through to here then it was some kind of node we
1392       // don't understand or there wasn't a matching unlock, so give
1393       // up trying to merge locks.
1394       lock_ops.trunc_to(0);
1395       return false;
1396     }
1397   }
1398   return true;
1399 
1400 }
1401 
1402 #ifndef PRODUCT
1403 //
1404 // Create a counter which counts the number of times this lock is acquired
1405 //
1406 void AbstractLockNode::create_lock_counter(JVMState* state) {
1407   _counter = OptoRuntime::new_named_counter(state, NamedCounter::LockCounter);
1408 }
1409 #endif
1410 
1411 void AbstractLockNode::set_eliminated() {
1412   _eliminate = true;
1413 #ifndef PRODUCT
1414   if (_counter) {
1415     // Update the counter to indicate that this lock was eliminated.
1416     // The counter update code will stay around even though the
1417     // optimizer will eliminate the lock operation itself.
1418     _counter->set_tag(NamedCounter::EliminatedLockCounter);
1419   }
1420 #endif
1421 }
1422 
1423 //=============================================================================
1424 Node *LockNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1425 
1426   // perform any generic optimizations first (returns 'this' or NULL)
1427   Node *result = SafePointNode::Ideal(phase, can_reshape);
1428 
1429   // Now see if we can optimize away this lock.  We don't actually
1430   // remove the locking here, we simply set the _eliminate flag which
1431   // prevents macro expansion from expanding the lock.  Since we don't
1432   // modify the graph, the value returned from this function is the
1433   // one computed above.
1434   if (result == NULL && can_reshape && EliminateLocks && !is_eliminated()) {
1435     //
1436     // If we are locking an unescaped object, the lock/unlock is unnecessary
1437     //
1438     ConnectionGraph *cgr = phase->C->congraph();
1439     PointsToNode::EscapeState es = PointsToNode::GlobalEscape;
1440     if (cgr != NULL)
1441       es = cgr->escape_state(obj_node(), phase);
1442     if (es != PointsToNode::UnknownEscape && es != PointsToNode::GlobalEscape) {
1443       // Mark it eliminated to update any counters
1444       this->set_eliminated();
1445       return result;
1446     }
1447 
1448     //
1449     // Try lock coarsening
1450     //
1451     PhaseIterGVN* iter = phase->is_IterGVN();
1452     if (iter != NULL) {
1453 
1454       GrowableArray<AbstractLockNode*>   lock_ops;
1455 
1456       Node *ctrl = next_control(in(0));
1457 
1458       // now search back for a matching Unlock
1459       if (find_matching_unlock(ctrl, this, lock_ops)) {
1460         // found an unlock directly preceding this lock.  This is the
1461         // case of single unlock directly control dependent on a
1462         // single lock which is the trivial version of case 1 or 2.
1463       } else if (ctrl->is_Region() ) {
1464         if (find_unlocks_for_region(ctrl->as_Region(), this, lock_ops)) {
1465         // found lock preceded by multiple unlocks along all paths
1466         // joining at this point which is case 3 in description above.
1467         }
1468       } else {
1469         // see if this lock comes from either half of an if and the
1470         // predecessors merges unlocks and the other half of the if
1471         // performs a lock.
1472         if (find_lock_and_unlock_through_if(ctrl, this, lock_ops)) {
1473           // found unlock splitting to an if with locks on both branches.
1474         }
1475       }
1476 
1477       if (lock_ops.length() > 0) {
1478         // add ourselves to the list of locks to be eliminated.
1479         lock_ops.append(this);
1480 
1481   #ifndef PRODUCT
1482         if (PrintEliminateLocks) {
1483           int locks = 0;
1484           int unlocks = 0;
1485           for (int i = 0; i < lock_ops.length(); i++) {
1486             AbstractLockNode* lock = lock_ops.at(i);
1487             if (lock->Opcode() == Op_Lock)
1488               locks++;
1489             else
1490               unlocks++;
1491             if (Verbose) {
1492               lock->dump(1);
1493             }
1494           }
1495           tty->print_cr("***Eliminated %d unlocks and %d locks", unlocks, locks);
1496         }
1497   #endif
1498 
1499         // for each of the identified locks, mark them
1500         // as eliminatable
1501         for (int i = 0; i < lock_ops.length(); i++) {
1502           AbstractLockNode* lock = lock_ops.at(i);
1503 
1504           // Mark it eliminated to update any counters
1505           lock->set_eliminated();
1506           lock->set_coarsened();
1507         }
1508       } else if (result != NULL && ctrl->is_Region() &&
1509                  iter->_worklist.member(ctrl)) {
1510         // We weren't able to find any opportunities but the region this
1511         // lock is control dependent on hasn't been processed yet so put
1512         // this lock back on the worklist so we can check again once any
1513         // region simplification has occurred.
1514         iter->_worklist.push(this);
1515       }
1516     }
1517   }
1518 
1519   return result;
1520 }
1521 
1522 //=============================================================================
1523 uint UnlockNode::size_of() const { return sizeof(*this); }
1524 
1525 //=============================================================================
1526 Node *UnlockNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1527 
1528   // perform any generic optimizations first (returns 'this' or NULL)
1529   Node * result = SafePointNode::Ideal(phase, can_reshape);
1530 
1531   // Now see if we can optimize away this unlock.  We don't actually
1532   // remove the unlocking here, we simply set the _eliminate flag which
1533   // prevents macro expansion from expanding the unlock.  Since we don't
1534   // modify the graph, the value returned from this function is the
1535   // one computed above.
1536   // Escape state is defined after Parse phase.
1537   if (result == NULL && can_reshape && EliminateLocks && !is_eliminated()) {
1538     //
1539     // If we are unlocking an unescaped object, the lock/unlock is unnecessary.
1540     //
1541     ConnectionGraph *cgr = phase->C->congraph();
1542     PointsToNode::EscapeState es = PointsToNode::GlobalEscape;
1543     if (cgr != NULL)
1544       es = cgr->escape_state(obj_node(), phase);
1545     if (es != PointsToNode::UnknownEscape && es != PointsToNode::GlobalEscape) {
1546       // Mark it eliminated to update any counters
1547       this->set_eliminated();
1548     }
1549   }
1550   return result;
1551 }