rev 3898 : 8005031: Some cleanup in c2 to prepare for incremental inlining support
Summary: collection of small changes to prepare for incremental inlining.
Reviewed-by:

   1 /*
   2  * Copyright (c) 2009, 2012, 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  */
  24 
  25 #include "precompiled.hpp"
  26 #include "compiler/compileLog.hpp"
  27 #include "opto/addnode.hpp"
  28 #include "opto/callGenerator.hpp"
  29 #include "opto/callnode.hpp"
  30 #include "opto/divnode.hpp"
  31 #include "opto/graphKit.hpp"
  32 #include "opto/idealKit.hpp"
  33 #include "opto/rootnode.hpp"
  34 #include "opto/runtime.hpp"
  35 #include "opto/stringopts.hpp"
  36 #include "opto/subnode.hpp"
  37 
  38 #define __ kit.
  39 
  40 class StringConcat : public ResourceObj {
  41  private:
  42   PhaseStringOpts*    _stringopts;
  43   Node*               _string_alloc;
  44   AllocateNode*       _begin;          // The allocation the begins the pattern
  45   CallStaticJavaNode* _end;            // The final call of the pattern.  Will either be
  46                                        // SB.toString or or String.<init>(SB.toString)
  47   bool                _multiple;       // indicates this is a fusion of two or more
  48                                        // separate StringBuilders
  49 
  50   Node*               _arguments;      // The list of arguments to be concatenated
  51   GrowableArray<int>  _mode;           // into a String along with a mode flag
  52                                        // indicating how to treat the value.
  53 
  54   Node_List           _control;        // List of control nodes that will be deleted
  55   Node_List           _uncommon_traps; // Uncommon traps that needs to be rewritten
  56                                        // to restart at the initial JVMState.
  57  public:
  58   // Mode for converting arguments to Strings
  59   enum {
  60     StringMode,
  61     IntMode,
  62     CharMode,
  63     StringNullCheckMode
  64   };
  65 
  66   StringConcat(PhaseStringOpts* stringopts, CallStaticJavaNode* end):
  67     _end(end),
  68     _begin(NULL),
  69     _multiple(false),
  70     _string_alloc(NULL),
  71     _stringopts(stringopts) {
  72     _arguments = new (_stringopts->C) Node(1);
  73     _arguments->del_req(0);
  74   }
  75 
  76   bool validate_control_flow();
  77 
  78   void merge_add() {
  79 #if 0
  80     // XXX This is place holder code for reusing an existing String
  81     // allocation but the logic for checking the state safety is
  82     // probably inadequate at the moment.
  83     CallProjections endprojs;
  84     sc->end()->extract_projections(&endprojs, false);
  85     if (endprojs.resproj != NULL) {
  86       for (SimpleDUIterator i(endprojs.resproj); i.has_next(); i.next()) {
  87         CallStaticJavaNode *use = i.get()->isa_CallStaticJava();
  88         if (use != NULL && use->method() != NULL &&
  89             use->method()->intrinsic_id() == vmIntrinsics::_String_String &&
  90             use->in(TypeFunc::Parms + 1) == endprojs.resproj) {
  91           // Found useless new String(sb.toString()) so reuse the newly allocated String
  92           // when creating the result instead of allocating a new one.
  93           sc->set_string_alloc(use->in(TypeFunc::Parms));
  94           sc->set_end(use);
  95         }
  96       }
  97     }
  98 #endif
  99   }
 100 
 101   StringConcat* merge(StringConcat* other, Node* arg);
 102 
 103   void set_allocation(AllocateNode* alloc) {
 104     _begin = alloc;
 105   }
 106 
 107   void append(Node* value, int mode) {
 108     _arguments->add_req(value);
 109     _mode.append(mode);
 110   }
 111   void push(Node* value, int mode) {
 112     _arguments->ins_req(0, value);
 113     _mode.insert_before(0, mode);
 114   }
 115 
 116   void push_string(Node* value) {
 117     push(value, StringMode);
 118   }
 119   void push_string_null_check(Node* value) {
 120     push(value, StringNullCheckMode);
 121   }
 122   void push_int(Node* value) {
 123     push(value, IntMode);
 124   }
 125   void push_char(Node* value) {
 126     push(value, CharMode);
 127   }
 128 
 129   static bool is_SB_toString(Node* call) {
 130     if (call->is_CallStaticJava()) {
 131       CallStaticJavaNode* csj = call->as_CallStaticJava();
 132       ciMethod* m = csj->method();
 133       if (m != NULL &&
 134           (m->intrinsic_id() == vmIntrinsics::_StringBuilder_toString ||
 135            m->intrinsic_id() == vmIntrinsics::_StringBuffer_toString)) {
 136         return true;
 137       }
 138     }
 139     return false;
 140   }
 141 
 142   static Node* skip_string_null_check(Node* value) {
 143     // Look for a diamond shaped Null check of toString() result
 144     // (could be code from String.valueOf()):
 145     // (Proj == NULL) ? "null":"CastPP(Proj)#NotNULL
 146     if (value->is_Phi()) {
 147       int true_path = value->as_Phi()->is_diamond_phi();
 148       if (true_path != 0) {
 149         // phi->region->if_proj->ifnode->bool
 150         BoolNode* b = value->in(0)->in(1)->in(0)->in(1)->as_Bool();
 151         Node* cmp = b->in(1);
 152         Node* v1 = cmp->in(1);
 153         Node* v2 = cmp->in(2);
 154         // Null check of the return of toString which can simply be skipped.
 155         if (b->_test._test == BoolTest::ne &&
 156             v2->bottom_type() == TypePtr::NULL_PTR &&
 157             value->in(true_path)->Opcode() == Op_CastPP &&
 158             value->in(true_path)->in(1) == v1 &&
 159             v1->is_Proj() && is_SB_toString(v1->in(0))) {
 160           return v1;
 161         }
 162       }
 163     }
 164     return value;
 165   }
 166 
 167   Node* argument(int i) {
 168     return _arguments->in(i);
 169   }
 170   Node* argument_uncast(int i) {
 171     Node* arg = argument(i);
 172     int amode = mode(i);
 173     if (amode == StringConcat::StringMode ||
 174         amode == StringConcat::StringNullCheckMode) {
 175       arg = skip_string_null_check(arg);
 176     }
 177     return arg;
 178   }
 179   void set_argument(int i, Node* value) {
 180     _arguments->set_req(i, value);
 181   }
 182   int num_arguments() {
 183     return _mode.length();
 184   }
 185   int mode(int i) {
 186     return _mode.at(i);
 187   }
 188   void add_control(Node* ctrl) {
 189     assert(!_control.contains(ctrl), "only push once");
 190     _control.push(ctrl);
 191   }
 192   CallStaticJavaNode* end() { return _end; }
 193   AllocateNode* begin() { return _begin; }
 194   Node* string_alloc() { return _string_alloc; }
 195 
 196   void eliminate_unneeded_control();
 197   void eliminate_initialize(InitializeNode* init);
 198   void eliminate_call(CallNode* call);
 199 
 200   void maybe_log_transform() {
 201     CompileLog* log = _stringopts->C->log();
 202     if (log != NULL) {
 203       log->head("replace_string_concat arguments='%d' string_alloc='%d' multiple='%d'",
 204                 num_arguments(),
 205                 _string_alloc != NULL,
 206                 _multiple);
 207       JVMState* p = _begin->jvms();
 208       while (p != NULL) {
 209         log->elem("jvms bci='%d' method='%d'", p->bci(), log->identify(p->method()));
 210         p = p->caller();
 211       }
 212       log->tail("replace_string_concat");
 213     }
 214   }
 215 
 216   void convert_uncommon_traps(GraphKit& kit, const JVMState* jvms) {
 217     for (uint u = 0; u < _uncommon_traps.size(); u++) {
 218       Node* uct = _uncommon_traps.at(u);
 219 
 220       // Build a new call using the jvms state of the allocate
 221       address call_addr = SharedRuntime::uncommon_trap_blob()->entry_point();
 222       const TypeFunc* call_type = OptoRuntime::uncommon_trap_Type();
 223       const TypePtr* no_memory_effects = NULL;
 224       Compile* C = _stringopts->C;
 225       CallStaticJavaNode* call = new (C) CallStaticJavaNode(call_type, call_addr, "uncommon_trap",
 226                                                             jvms->bci(), no_memory_effects);
 227       for (int e = 0; e < TypeFunc::Parms; e++) {
 228         call->init_req(e, uct->in(e));
 229       }
 230       // Set the trap request to record intrinsic failure if this trap
 231       // is taken too many times.  Ideally we would handle then traps by
 232       // doing the original bookkeeping in the MDO so that if it caused
 233       // the code to be thrown out we could still recompile and use the
 234       // optimization.  Failing the uncommon traps doesn't really mean
 235       // that the optimization is a bad idea but there's no other way to
 236       // do the MDO updates currently.
 237       int trap_request = Deoptimization::make_trap_request(Deoptimization::Reason_intrinsic,
 238                                                            Deoptimization::Action_make_not_entrant);
 239       call->init_req(TypeFunc::Parms, __ intcon(trap_request));
 240       kit.add_safepoint_edges(call);
 241 
 242       _stringopts->gvn()->transform(call);
 243       C->gvn_replace_by(uct, call);
 244       uct->disconnect_inputs(NULL, C);
 245     }
 246   }
 247 
 248   void cleanup() {
 249     // disconnect the hook node
 250     _arguments->disconnect_inputs(NULL, _stringopts->C);
 251   }
 252 };
 253 
 254 
 255 void StringConcat::eliminate_unneeded_control() {
 256   for (uint i = 0; i < _control.size(); i++) {
 257     Node* n = _control.at(i);
 258     if (n->is_Allocate()) {
 259       eliminate_initialize(n->as_Allocate()->initialization());
 260     }
 261     if (n->is_Call()) {
 262       if (n != _end) {
 263         eliminate_call(n->as_Call());
 264       }
 265     } else if (n->is_IfTrue()) {
 266       Compile* C = _stringopts->C;
 267       C->gvn_replace_by(n, n->in(0)->in(0));
 268       C->gvn_replace_by(n->in(0), C->top());
 269     }
 270   }
 271 }
 272 
 273 
 274 StringConcat* StringConcat::merge(StringConcat* other, Node* arg) {
 275   StringConcat* result = new StringConcat(_stringopts, _end);
 276   for (uint x = 0; x < _control.size(); x++) {
 277     Node* n = _control.at(x);
 278     if (n->is_Call()) {
 279       result->_control.push(n);
 280     }
 281   }
 282   for (uint x = 0; x < other->_control.size(); x++) {
 283     Node* n = other->_control.at(x);
 284     if (n->is_Call()) {
 285       result->_control.push(n);
 286     }
 287   }
 288   assert(result->_control.contains(other->_end), "what?");
 289   assert(result->_control.contains(_begin), "what?");
 290   for (int x = 0; x < num_arguments(); x++) {
 291     Node* argx = argument_uncast(x);
 292     if (argx == arg) {
 293       // replace the toString result with the all the arguments that
 294       // made up the other StringConcat
 295       for (int y = 0; y < other->num_arguments(); y++) {
 296         result->append(other->argument(y), other->mode(y));
 297       }
 298     } else {
 299       result->append(argx, mode(x));
 300     }
 301   }
 302   result->set_allocation(other->_begin);
 303   result->_multiple = true;
 304   return result;
 305 }
 306 
 307 
 308 void StringConcat::eliminate_call(CallNode* call) {
 309   Compile* C = _stringopts->C;
 310   CallProjections projs;
 311   call->extract_projections(&projs, false);
 312   if (projs.fallthrough_catchproj != NULL) {
 313     C->gvn_replace_by(projs.fallthrough_catchproj, call->in(TypeFunc::Control));
 314   }
 315   if (projs.fallthrough_memproj != NULL) {
 316     C->gvn_replace_by(projs.fallthrough_memproj, call->in(TypeFunc::Memory));
 317   }
 318   if (projs.catchall_memproj != NULL) {
 319     C->gvn_replace_by(projs.catchall_memproj, C->top());
 320   }
 321   if (projs.fallthrough_ioproj != NULL) {
 322     C->gvn_replace_by(projs.fallthrough_ioproj, call->in(TypeFunc::I_O));
 323   }
 324   if (projs.catchall_ioproj != NULL) {
 325     C->gvn_replace_by(projs.catchall_ioproj, C->top());
 326   }
 327   if (projs.catchall_catchproj != NULL) {
 328     // EA can't cope with the partially collapsed graph this
 329     // creates so put it on the worklist to be collapsed later.
 330     for (SimpleDUIterator i(projs.catchall_catchproj); i.has_next(); i.next()) {
 331       Node *use = i.get();
 332       int opc = use->Opcode();
 333       if (opc == Op_CreateEx || opc == Op_Region) {
 334         _stringopts->record_dead_node(use);
 335       }
 336     }
 337     C->gvn_replace_by(projs.catchall_catchproj, C->top());
 338   }
 339   if (projs.resproj != NULL) {
 340     C->gvn_replace_by(projs.resproj, C->top());
 341   }
 342   C->gvn_replace_by(call, C->top());
 343 }
 344 
 345 void StringConcat::eliminate_initialize(InitializeNode* init) {
 346   Compile* C = _stringopts->C;
 347 
 348   // Eliminate Initialize node.
 349   assert(init->outcnt() <= 2, "only a control and memory projection expected");
 350   assert(init->req() <= InitializeNode::RawStores, "no pending inits");
 351   Node *ctrl_proj = init->proj_out(TypeFunc::Control);
 352   if (ctrl_proj != NULL) {
 353     C->gvn_replace_by(ctrl_proj, init->in(TypeFunc::Control));
 354   }
 355   Node *mem_proj = init->proj_out(TypeFunc::Memory);
 356   if (mem_proj != NULL) {
 357     Node *mem = init->in(TypeFunc::Memory);
 358     C->gvn_replace_by(mem_proj, mem);
 359   }
 360   C->gvn_replace_by(init, C->top());
 361   init->disconnect_inputs(NULL, C);
 362 }
 363 
 364 Node_List PhaseStringOpts::collect_toString_calls() {
 365   Node_List string_calls;
 366   Node_List worklist;
 367 
 368   _visited.Clear();
 369 
 370   // Prime the worklist
 371   for (uint i = 1; i < C->root()->len(); i++) {
 372     Node* n = C->root()->in(i);
 373     if (n != NULL && !_visited.test_set(n->_idx)) {
 374       worklist.push(n);
 375     }
 376   }
 377 
 378   while (worklist.size() > 0) {
 379     Node* ctrl = worklist.pop();
 380     if (StringConcat::is_SB_toString(ctrl)) {
 381       CallStaticJavaNode* csj = ctrl->as_CallStaticJava();
 382       string_calls.push(csj);
 383     }
 384     if (ctrl->in(0) != NULL && !_visited.test_set(ctrl->in(0)->_idx)) {
 385       worklist.push(ctrl->in(0));
 386     }
 387     if (ctrl->is_Region()) {
 388       for (uint i = 1; i < ctrl->len(); i++) {
 389         if (ctrl->in(i) != NULL && !_visited.test_set(ctrl->in(i)->_idx)) {
 390           worklist.push(ctrl->in(i));
 391         }
 392       }
 393     }
 394   }
 395   return string_calls;
 396 }
 397 
 398 
 399 StringConcat* PhaseStringOpts::build_candidate(CallStaticJavaNode* call) {
 400   ciMethod* m = call->method();
 401   ciSymbol* string_sig;
 402   ciSymbol* int_sig;
 403   ciSymbol* char_sig;
 404   if (m->holder() == C->env()->StringBuilder_klass()) {
 405     string_sig = ciSymbol::String_StringBuilder_signature();
 406     int_sig = ciSymbol::int_StringBuilder_signature();
 407     char_sig = ciSymbol::char_StringBuilder_signature();
 408   } else if (m->holder() == C->env()->StringBuffer_klass()) {
 409     string_sig = ciSymbol::String_StringBuffer_signature();
 410     int_sig = ciSymbol::int_StringBuffer_signature();
 411     char_sig = ciSymbol::char_StringBuffer_signature();
 412   } else {
 413     return NULL;
 414   }
 415 #ifndef PRODUCT
 416   if (PrintOptimizeStringConcat) {
 417     tty->print("considering toString call in ");
 418     call->jvms()->dump_spec(tty); tty->cr();
 419   }
 420 #endif
 421 
 422   StringConcat* sc = new StringConcat(this, call);
 423 
 424   AllocateNode* alloc = NULL;
 425   InitializeNode* init = NULL;
 426 
 427   // possible opportunity for StringBuilder fusion
 428   CallStaticJavaNode* cnode = call;
 429   while (cnode) {
 430     Node* recv = cnode->in(TypeFunc::Parms)->uncast();
 431     if (recv->is_Proj()) {
 432       recv = recv->in(0);
 433     }
 434     cnode = recv->isa_CallStaticJava();
 435     if (cnode == NULL) {
 436       alloc = recv->isa_Allocate();
 437       if (alloc == NULL) {
 438         break;
 439       }
 440       // Find the constructor call
 441       Node* result = alloc->result_cast();
 442       if (result == NULL || !result->is_CheckCastPP()) {
 443         // strange looking allocation
 444 #ifndef PRODUCT
 445         if (PrintOptimizeStringConcat) {
 446           tty->print("giving up because allocation looks strange ");
 447           alloc->jvms()->dump_spec(tty); tty->cr();
 448         }
 449 #endif
 450         break;
 451       }
 452       Node* constructor = NULL;
 453       for (SimpleDUIterator i(result); i.has_next(); i.next()) {
 454         CallStaticJavaNode *use = i.get()->isa_CallStaticJava();
 455         if (use != NULL &&
 456             use->method() != NULL &&
 457             !use->method()->is_static() &&
 458             use->method()->name() == ciSymbol::object_initializer_name() &&
 459             use->method()->holder() == m->holder()) {
 460           // Matched the constructor.
 461           ciSymbol* sig = use->method()->signature()->as_symbol();
 462           if (sig == ciSymbol::void_method_signature() ||
 463               sig == ciSymbol::int_void_signature() ||
 464               sig == ciSymbol::string_void_signature()) {
 465             if (sig == ciSymbol::string_void_signature()) {
 466               // StringBuilder(String) so pick this up as the first argument
 467               assert(use->in(TypeFunc::Parms + 1) != NULL, "what?");
 468               const Type* type = _gvn->type(use->in(TypeFunc::Parms + 1));
 469               if (type == TypePtr::NULL_PTR) {
 470                 // StringBuilder(null) throws exception.
 471 #ifndef PRODUCT
 472                 if (PrintOptimizeStringConcat) {
 473                   tty->print("giving up because StringBuilder(null) throws exception");
 474                   alloc->jvms()->dump_spec(tty); tty->cr();
 475                 }
 476 #endif
 477                 return NULL;
 478               }
 479               // StringBuilder(str) argument needs null check.
 480               sc->push_string_null_check(use->in(TypeFunc::Parms + 1));
 481             }
 482             // The int variant takes an initial size for the backing
 483             // array so just treat it like the void version.
 484             constructor = use;
 485           } else {
 486 #ifndef PRODUCT
 487             if (PrintOptimizeStringConcat) {
 488               tty->print("unexpected constructor signature: %s", sig->as_utf8());
 489             }
 490 #endif
 491           }
 492           break;
 493         }
 494       }
 495       if (constructor == NULL) {
 496         // couldn't find constructor
 497 #ifndef PRODUCT
 498         if (PrintOptimizeStringConcat) {
 499           tty->print("giving up because couldn't find constructor ");
 500           alloc->jvms()->dump_spec(tty); tty->cr();
 501         }
 502 #endif
 503         break;
 504       }
 505 
 506       // Walked all the way back and found the constructor call so see
 507       // if this call converted into a direct string concatenation.
 508       sc->add_control(call);
 509       sc->add_control(constructor);
 510       sc->add_control(alloc);
 511       sc->set_allocation(alloc);
 512       if (sc->validate_control_flow()) {
 513         return sc;
 514       } else {
 515         return NULL;
 516       }
 517     } else if (cnode->method() == NULL) {
 518       break;
 519     } else if (!cnode->method()->is_static() &&
 520                cnode->method()->holder() == m->holder() &&
 521                cnode->method()->name() == ciSymbol::append_name() &&
 522                (cnode->method()->signature()->as_symbol() == string_sig ||
 523                 cnode->method()->signature()->as_symbol() == char_sig ||
 524                 cnode->method()->signature()->as_symbol() == int_sig)) {
 525       sc->add_control(cnode);
 526       Node* arg = cnode->in(TypeFunc::Parms + 1);
 527       if (cnode->method()->signature()->as_symbol() == int_sig) {
 528         sc->push_int(arg);
 529       } else if (cnode->method()->signature()->as_symbol() == char_sig) {
 530         sc->push_char(arg);
 531       } else {
 532         if (arg->is_Proj() && arg->in(0)->is_CallStaticJava()) {
 533           CallStaticJavaNode* csj = arg->in(0)->as_CallStaticJava();
 534           if (csj->method() != NULL &&
 535               csj->method()->intrinsic_id() == vmIntrinsics::_Integer_toString &&
 536               arg->outcnt() == 1) {
 537             // _control is the list of StringBuilder calls nodes which
 538             // will be replaced by new String code after this optimization.
 539             // Integer::toString() call is not part of StringBuilder calls
 540             // chain. It could be eliminated only if its result is used
 541             // only by this SB calls chain.
 542             // Another limitation: it should be used only once because
 543             // it is unknown that it is used only by this SB calls chain
 544             // until all related SB calls nodes are collected.
 545             assert(arg->unique_out() == cnode, "sanity");
 546             sc->add_control(csj);
 547             sc->push_int(csj->in(TypeFunc::Parms));
 548             continue;
 549           }
 550         }
 551         sc->push_string(arg);
 552       }
 553       continue;
 554     } else {
 555       // some unhandled signature
 556 #ifndef PRODUCT
 557       if (PrintOptimizeStringConcat) {
 558         tty->print("giving up because encountered unexpected signature ");
 559         cnode->tf()->dump(); tty->cr();
 560         cnode->in(TypeFunc::Parms + 1)->dump();
 561       }
 562 #endif
 563       break;
 564     }
 565   }
 566   return NULL;
 567 }
 568 
 569 
 570 PhaseStringOpts::PhaseStringOpts(PhaseGVN* gvn, Unique_Node_List*):
 571   Phase(StringOpts),
 572   _gvn(gvn),
 573   _visited(Thread::current()->resource_area()) {
 574 
 575   assert(OptimizeStringConcat, "shouldn't be here");
 576 
 577   size_table_field = C->env()->Integer_klass()->get_field_by_name(ciSymbol::make("sizeTable"),
 578                                                                   ciSymbol::make("[I"), true);
 579   if (size_table_field == NULL) {
 580     // Something wrong so give up.
 581     assert(false, "why can't we find Integer.sizeTable?");
 582     return;
 583   }
 584 
 585   // Collect the types needed to talk about the various slices of memory
 586   char_adr_idx = C->get_alias_index(TypeAryPtr::CHARS);
 587 
 588   // For each locally allocated StringBuffer see if the usages can be
 589   // collapsed into a single String construction.
 590 
 591   // Run through the list of allocation looking for SB.toString to see
 592   // if it's possible to fuse the usage of the SB into a single String
 593   // construction.
 594   GrowableArray<StringConcat*> concats;
 595   Node_List toStrings = collect_toString_calls();
 596   while (toStrings.size() > 0) {
 597     StringConcat* sc = build_candidate(toStrings.pop()->as_CallStaticJava());
 598     if (sc != NULL) {
 599       concats.push(sc);
 600     }
 601   }
 602 
 603   // try to coalesce separate concats
 604  restart:
 605   for (int c = 0; c < concats.length(); c++) {
 606     StringConcat* sc = concats.at(c);
 607     for (int i = 0; i < sc->num_arguments(); i++) {
 608       Node* arg = sc->argument_uncast(i);
 609       if (arg->is_Proj() && StringConcat::is_SB_toString(arg->in(0))) {
 610         CallStaticJavaNode* csj = arg->in(0)->as_CallStaticJava();
 611         for (int o = 0; o < concats.length(); o++) {
 612           if (c == o) continue;
 613           StringConcat* other = concats.at(o);
 614           if (other->end() == csj) {
 615 #ifndef PRODUCT
 616             if (PrintOptimizeStringConcat) {
 617               tty->print_cr("considering stacked concats");
 618             }
 619 #endif
 620 
 621             StringConcat* merged = sc->merge(other, arg);
 622             if (merged->validate_control_flow()) {
 623 #ifndef PRODUCT
 624               if (PrintOptimizeStringConcat) {
 625                 tty->print_cr("stacking would succeed");
 626               }
 627 #endif
 628               if (c < o) {
 629                 concats.remove_at(o);
 630                 concats.at_put(c, merged);
 631               } else {
 632                 concats.remove_at(c);
 633                 concats.at_put(o, merged);
 634               }
 635               goto restart;
 636             } else {
 637 #ifndef PRODUCT
 638               if (PrintOptimizeStringConcat) {
 639                 tty->print_cr("stacking would fail");
 640               }
 641 #endif
 642             }
 643           }
 644         }
 645       }
 646     }
 647   }
 648 
 649 
 650   for (int c = 0; c < concats.length(); c++) {
 651     StringConcat* sc = concats.at(c);
 652     replace_string_concat(sc);
 653   }
 654 
 655   remove_dead_nodes();
 656 }
 657 
 658 void PhaseStringOpts::record_dead_node(Node* dead) {
 659   dead_worklist.push(dead);
 660 }
 661 
 662 void PhaseStringOpts::remove_dead_nodes() {
 663   // Delete any dead nodes to make things clean enough that escape
 664   // analysis doesn't get unhappy.
 665   while (dead_worklist.size() > 0) {
 666     Node* use = dead_worklist.pop();
 667     int opc = use->Opcode();
 668     switch (opc) {
 669       case Op_Region: {
 670         uint i = 1;
 671         for (i = 1; i < use->req(); i++) {
 672           if (use->in(i) != C->top()) {
 673             break;
 674           }
 675         }
 676         if (i >= use->req()) {
 677           for (SimpleDUIterator i(use); i.has_next(); i.next()) {
 678             Node* m = i.get();
 679             if (m->is_Phi()) {
 680               dead_worklist.push(m);
 681             }
 682           }
 683           C->gvn_replace_by(use, C->top());
 684         }
 685         break;
 686       }
 687       case Op_AddP:
 688       case Op_CreateEx: {
 689         // Recurisvely clean up references to CreateEx so EA doesn't
 690         // get unhappy about the partially collapsed graph.
 691         for (SimpleDUIterator i(use); i.has_next(); i.next()) {
 692           Node* m = i.get();
 693           if (m->is_AddP()) {
 694             dead_worklist.push(m);
 695           }
 696         }
 697         C->gvn_replace_by(use, C->top());
 698         break;
 699       }
 700       case Op_Phi:
 701         if (use->in(0) == C->top()) {
 702           C->gvn_replace_by(use, C->top());
 703         }
 704         break;
 705     }
 706   }
 707 }
 708 
 709 
 710 bool StringConcat::validate_control_flow() {
 711   // We found all the calls and arguments now lets see if it's
 712   // safe to transform the graph as we would expect.
 713 
 714   // Check to see if this resulted in too many uncommon traps previously
 715   if (Compile::current()->too_many_traps(_begin->jvms()->method(), _begin->jvms()->bci(),
 716                         Deoptimization::Reason_intrinsic)) {
 717     return false;
 718   }
 719 
 720   // Walk backwards over the control flow from toString to the
 721   // allocation and make sure all the control flow is ok.  This
 722   // means it's either going to be eliminated once the calls are
 723   // removed or it can safely be transformed into an uncommon
 724   // trap.
 725 
 726   int null_check_count = 0;
 727   Unique_Node_List ctrl_path;
 728 
 729   assert(_control.contains(_begin), "missing");
 730   assert(_control.contains(_end), "missing");
 731 
 732   // Collect the nodes that we know about and will eliminate into ctrl_path
 733   for (uint i = 0; i < _control.size(); i++) {
 734     // Push the call and it's control projection
 735     Node* n = _control.at(i);
 736     if (n->is_Allocate()) {
 737       AllocateNode* an = n->as_Allocate();
 738       InitializeNode* init = an->initialization();
 739       ctrl_path.push(init);
 740       ctrl_path.push(init->as_Multi()->proj_out(0));
 741     }
 742     if (n->is_Call()) {
 743       CallNode* cn = n->as_Call();
 744       ctrl_path.push(cn);
 745       ctrl_path.push(cn->proj_out(0));
 746       ctrl_path.push(cn->proj_out(0)->unique_out());
 747       if (cn->proj_out(0)->unique_out()->as_Catch()->proj_out(0) != NULL) {
 748         ctrl_path.push(cn->proj_out(0)->unique_out()->as_Catch()->proj_out(0));
 749       }
 750     } else {
 751       ShouldNotReachHere();
 752     }
 753   }
 754 
 755   // Skip backwards through the control checking for unexpected contro flow
 756   Node* ptr = _end;
 757   bool fail = false;
 758   while (ptr != _begin) {
 759     if (ptr->is_Call() && ctrl_path.member(ptr)) {
 760       ptr = ptr->in(0);
 761     } else if (ptr->is_CatchProj() && ctrl_path.member(ptr)) {
 762       ptr = ptr->in(0)->in(0)->in(0);
 763       assert(ctrl_path.member(ptr), "should be a known piece of control");
 764     } else if (ptr->is_IfTrue()) {
 765       IfNode* iff = ptr->in(0)->as_If();
 766       BoolNode* b = iff->in(1)->isa_Bool();
 767       
 768       if (b == NULL) {
 769         fail = true;
 770         break;
 771       }
 772 
 773       Node* cmp = b->in(1);
 774       Node* v1 = cmp->in(1);
 775       Node* v2 = cmp->in(2);
 776       Node* otherproj = iff->proj_out(1 - ptr->as_Proj()->_con);
 777 
 778       // Null check of the return of append which can simply be eliminated
 779       if (b->_test._test == BoolTest::ne &&
 780           v2->bottom_type() == TypePtr::NULL_PTR &&
 781           v1->is_Proj() && ctrl_path.member(v1->in(0))) {
 782         // NULL check of the return value of the append
 783         null_check_count++;
 784         if (otherproj->outcnt() == 1) {
 785           CallStaticJavaNode* call = otherproj->unique_out()->isa_CallStaticJava();
 786           if (call != NULL && call->_name != NULL && strcmp(call->_name, "uncommon_trap") == 0) {
 787             ctrl_path.push(call);
 788           }
 789         }
 790         _control.push(ptr);
 791         ptr = ptr->in(0)->in(0);
 792         continue;
 793       }
 794 
 795       // A test which leads to an uncommon trap which should be safe.
 796       // Later this trap will be converted into a trap that restarts
 797       // at the beginning.
 798       if (otherproj->outcnt() == 1) {
 799         CallStaticJavaNode* call = otherproj->unique_out()->isa_CallStaticJava();
 800         if (call != NULL && call->_name != NULL && strcmp(call->_name, "uncommon_trap") == 0) {
 801           // control flow leads to uct so should be ok
 802           _uncommon_traps.push(call);
 803           ctrl_path.push(call);
 804           ptr = ptr->in(0)->in(0);
 805           continue;
 806         }
 807       }
 808 
 809 #ifndef PRODUCT
 810       // Some unexpected control flow we don't know how to handle.
 811       if (PrintOptimizeStringConcat) {
 812         tty->print_cr("failing with unknown test");
 813         b->dump();
 814         cmp->dump();
 815         v1->dump();
 816         v2->dump();
 817         tty->cr();
 818       }
 819 #endif
 820       fail = true;
 821       break;
 822     } else if (ptr->is_Proj() && ptr->in(0)->is_Initialize()) {
 823       ptr = ptr->in(0)->in(0);
 824     } else if (ptr->is_Region()) {
 825       Node* copy = ptr->as_Region()->is_copy();
 826       if (copy != NULL) {
 827         ptr = copy;
 828         continue;
 829       }
 830       if (ptr->req() == 3 &&
 831           ptr->in(1) != NULL && ptr->in(1)->is_Proj() &&
 832           ptr->in(2) != NULL && ptr->in(2)->is_Proj() &&
 833           ptr->in(1)->in(0) == ptr->in(2)->in(0) &&
 834           ptr->in(1)->in(0) != NULL && ptr->in(1)->in(0)->is_If()) {
 835         // Simple diamond.
 836         // XXX should check for possibly merging stores.  simple data merges are ok.
 837         ptr = ptr->in(1)->in(0)->in(0);
 838         continue;
 839       }
 840 #ifndef PRODUCT
 841       if (PrintOptimizeStringConcat) {
 842         tty->print_cr("fusion would fail for region");
 843         _begin->dump();
 844         ptr->dump(2);
 845       }
 846 #endif
 847       fail = true;
 848       break;
 849     } else {
 850       // other unknown control
 851       if (!fail) {
 852 #ifndef PRODUCT
 853         if (PrintOptimizeStringConcat) {
 854           tty->print_cr("fusion would fail for");
 855           _begin->dump();
 856         }
 857 #endif
 858         fail = true;
 859       }
 860 #ifndef PRODUCT
 861       if (PrintOptimizeStringConcat) {
 862         ptr->dump();
 863       }
 864 #endif
 865       ptr = ptr->in(0);
 866     }
 867   }
 868 #ifndef PRODUCT
 869   if (PrintOptimizeStringConcat && fail) {
 870     tty->cr();
 871   }
 872 #endif
 873   if (fail) return !fail;
 874 
 875   // Validate that all these results produced are contained within
 876   // this cluster of objects.  First collect all the results produced
 877   // by calls in the region.
 878   _stringopts->_visited.Clear();
 879   Node_List worklist;
 880   Node* final_result = _end->proj_out(TypeFunc::Parms);
 881   for (uint i = 0; i < _control.size(); i++) {
 882     CallNode* cnode = _control.at(i)->isa_Call();
 883     if (cnode != NULL) {
 884       _stringopts->_visited.test_set(cnode->_idx);
 885     }
 886     Node* result = cnode != NULL ? cnode->proj_out(TypeFunc::Parms) : NULL;
 887     if (result != NULL && result != final_result) {
 888       worklist.push(result);
 889     }
 890   }
 891 
 892   Node* last_result = NULL;
 893   while (worklist.size() > 0) {
 894     Node* result = worklist.pop();
 895     if (_stringopts->_visited.test_set(result->_idx))
 896       continue;
 897     for (SimpleDUIterator i(result); i.has_next(); i.next()) {
 898       Node *use = i.get();
 899       if (ctrl_path.member(use)) {
 900         // already checked this
 901         continue;
 902       }
 903       int opc = use->Opcode();
 904       if (opc == Op_CmpP || opc == Op_Node) {
 905         ctrl_path.push(use);
 906         continue;
 907       }
 908       if (opc == Op_CastPP || opc == Op_CheckCastPP) {
 909         for (SimpleDUIterator j(use); j.has_next(); j.next()) {
 910           worklist.push(j.get());
 911         }
 912         worklist.push(use->in(1));
 913         ctrl_path.push(use);
 914         continue;
 915       }
 916 #ifndef PRODUCT
 917       if (PrintOptimizeStringConcat) {
 918         if (result != last_result) {
 919           last_result = result;
 920           tty->print_cr("extra uses for result:");
 921           last_result->dump();
 922         }
 923         use->dump();
 924       }
 925 #endif
 926       fail = true;
 927       break;
 928     }
 929   }
 930 
 931 #ifndef PRODUCT
 932   if (PrintOptimizeStringConcat && !fail) {
 933     ttyLocker ttyl;
 934     tty->cr();
 935     tty->print("fusion would succeed (%d %d) for ", null_check_count, _uncommon_traps.size());
 936     _begin->jvms()->dump_spec(tty); tty->cr();
 937     for (int i = 0; i < num_arguments(); i++) {
 938       argument(i)->dump();
 939     }
 940     _control.dump();
 941     tty->cr();
 942   }
 943 #endif
 944 
 945   return !fail;
 946 }
 947 
 948 Node* PhaseStringOpts::fetch_static_field(GraphKit& kit, ciField* field) {
 949   const TypeInstPtr* mirror_type = TypeInstPtr::make(field->holder()->java_mirror());
 950   Node* klass_node = __ makecon(mirror_type);
 951   BasicType bt = field->layout_type();
 952   ciType* field_klass = field->type();
 953 
 954   const Type *type;
 955   if( bt == T_OBJECT ) {
 956     if (!field->type()->is_loaded()) {
 957       type = TypeInstPtr::BOTTOM;
 958     } else if (field->is_constant()) {
 959       // This can happen if the constant oop is non-perm.
 960       ciObject* con = field->constant_value().as_object();
 961       // Do not "join" in the previous type; it doesn't add value,
 962       // and may yield a vacuous result if the field is of interface type.
 963       type = TypeOopPtr::make_from_constant(con, true)->isa_oopptr();
 964       assert(type != NULL, "field singleton type must be consistent");
 965       return __ makecon(type);
 966     } else {
 967       type = TypeOopPtr::make_from_klass(field_klass->as_klass());
 968     }
 969   } else {
 970     type = Type::get_const_basic_type(bt);
 971   }
 972 
 973   return kit.make_load(NULL, kit.basic_plus_adr(klass_node, field->offset_in_bytes()),
 974                        type, T_OBJECT,
 975                        C->get_alias_index(mirror_type->add_offset(field->offset_in_bytes())));
 976 }
 977 
 978 Node* PhaseStringOpts::int_stringSize(GraphKit& kit, Node* arg) {
 979   RegionNode *final_merge = new (C) RegionNode(3);
 980   kit.gvn().set_type(final_merge, Type::CONTROL);
 981   Node* final_size = new (C) PhiNode(final_merge, TypeInt::INT);
 982   kit.gvn().set_type(final_size, TypeInt::INT);
 983 
 984   IfNode* iff = kit.create_and_map_if(kit.control(),
 985                                       __ Bool(__ CmpI(arg, __ intcon(0x80000000)), BoolTest::ne),
 986                                       PROB_FAIR, COUNT_UNKNOWN);
 987   Node* is_min = __ IfFalse(iff);
 988   final_merge->init_req(1, is_min);
 989   final_size->init_req(1, __ intcon(11));
 990 
 991   kit.set_control(__ IfTrue(iff));
 992   if (kit.stopped()) {
 993     final_merge->init_req(2, C->top());
 994     final_size->init_req(2, C->top());
 995   } else {
 996 
 997     // int size = (i < 0) ? stringSize(-i) + 1 : stringSize(i);
 998     RegionNode *r = new (C) RegionNode(3);
 999     kit.gvn().set_type(r, Type::CONTROL);
1000     Node *phi = new (C) PhiNode(r, TypeInt::INT);
1001     kit.gvn().set_type(phi, TypeInt::INT);
1002     Node *size = new (C) PhiNode(r, TypeInt::INT);
1003     kit.gvn().set_type(size, TypeInt::INT);
1004     Node* chk = __ CmpI(arg, __ intcon(0));
1005     Node* p = __ Bool(chk, BoolTest::lt);
1006     IfNode* iff = kit.create_and_map_if(kit.control(), p, PROB_FAIR, COUNT_UNKNOWN);
1007     Node* lessthan = __ IfTrue(iff);
1008     Node* greaterequal = __ IfFalse(iff);
1009     r->init_req(1, lessthan);
1010     phi->init_req(1, __ SubI(__ intcon(0), arg));
1011     size->init_req(1, __ intcon(1));
1012     r->init_req(2, greaterequal);
1013     phi->init_req(2, arg);
1014     size->init_req(2, __ intcon(0));
1015     kit.set_control(r);
1016     C->record_for_igvn(r);
1017     C->record_for_igvn(phi);
1018     C->record_for_igvn(size);
1019 
1020     // for (int i=0; ; i++)
1021     //   if (x <= sizeTable[i])
1022     //     return i+1;
1023 
1024     // Add loop predicate first.
1025     kit.add_predicate();
1026 
1027     RegionNode *loop = new (C) RegionNode(3);
1028     loop->init_req(1, kit.control());
1029     kit.gvn().set_type(loop, Type::CONTROL);
1030 
1031     Node *index = new (C) PhiNode(loop, TypeInt::INT);
1032     index->init_req(1, __ intcon(0));
1033     kit.gvn().set_type(index, TypeInt::INT);
1034     kit.set_control(loop);
1035     Node* sizeTable = fetch_static_field(kit, size_table_field);
1036 
1037     Node* value = kit.load_array_element(NULL, sizeTable, index, TypeAryPtr::INTS);
1038     C->record_for_igvn(value);
1039     Node* limit = __ CmpI(phi, value);
1040     Node* limitb = __ Bool(limit, BoolTest::le);
1041     IfNode* iff2 = kit.create_and_map_if(kit.control(), limitb, PROB_MIN, COUNT_UNKNOWN);
1042     Node* lessEqual = __ IfTrue(iff2);
1043     Node* greater = __ IfFalse(iff2);
1044 
1045     loop->init_req(2, greater);
1046     index->init_req(2, __ AddI(index, __ intcon(1)));
1047 
1048     kit.set_control(lessEqual);
1049     C->record_for_igvn(loop);
1050     C->record_for_igvn(index);
1051 
1052     final_merge->init_req(2, kit.control());
1053     final_size->init_req(2, __ AddI(__ AddI(index, size), __ intcon(1)));
1054   }
1055 
1056   kit.set_control(final_merge);
1057   C->record_for_igvn(final_merge);
1058   C->record_for_igvn(final_size);
1059 
1060   return final_size;
1061 }
1062 
1063 void PhaseStringOpts::int_getChars(GraphKit& kit, Node* arg, Node* char_array, Node* start, Node* end) {
1064   RegionNode *final_merge = new (C) RegionNode(4);
1065   kit.gvn().set_type(final_merge, Type::CONTROL);
1066   Node *final_mem = PhiNode::make(final_merge, kit.memory(char_adr_idx), Type::MEMORY, TypeAryPtr::CHARS);
1067   kit.gvn().set_type(final_mem, Type::MEMORY);
1068 
1069   // need to handle Integer.MIN_VALUE specially because negating doesn't make it positive
1070   {
1071     // i == MIN_VALUE
1072     IfNode* iff = kit.create_and_map_if(kit.control(),
1073                                         __ Bool(__ CmpI(arg, __ intcon(0x80000000)), BoolTest::ne),
1074                                         PROB_FAIR, COUNT_UNKNOWN);
1075 
1076     Node* old_mem = kit.memory(char_adr_idx);
1077 
1078     kit.set_control(__ IfFalse(iff));
1079     if (kit.stopped()) {
1080       // Statically not equal to MIN_VALUE so this path is dead
1081       final_merge->init_req(3, kit.control());
1082     } else {
1083       copy_string(kit, __ makecon(TypeInstPtr::make(C->env()->the_min_jint_string())),
1084                   char_array, start);
1085       final_merge->init_req(3, kit.control());
1086       final_mem->init_req(3, kit.memory(char_adr_idx));
1087     }
1088 
1089     kit.set_control(__ IfTrue(iff));
1090     kit.set_memory(old_mem, char_adr_idx);
1091   }
1092 
1093 
1094   // Simplified version of Integer.getChars
1095 
1096   // int q, r;
1097   // int charPos = index;
1098   Node* charPos = end;
1099 
1100   // char sign = 0;
1101 
1102   Node* i = arg;
1103   Node* sign = __ intcon(0);
1104 
1105   // if (i < 0) {
1106   //     sign = '-';
1107   //     i = -i;
1108   // }
1109   {
1110     IfNode* iff = kit.create_and_map_if(kit.control(),
1111                                         __ Bool(__ CmpI(arg, __ intcon(0)), BoolTest::lt),
1112                                         PROB_FAIR, COUNT_UNKNOWN);
1113 
1114     RegionNode *merge = new (C) RegionNode(3);
1115     kit.gvn().set_type(merge, Type::CONTROL);
1116     i = new (C) PhiNode(merge, TypeInt::INT);
1117     kit.gvn().set_type(i, TypeInt::INT);
1118     sign = new (C) PhiNode(merge, TypeInt::INT);
1119     kit.gvn().set_type(sign, TypeInt::INT);
1120 
1121     merge->init_req(1, __ IfTrue(iff));
1122     i->init_req(1, __ SubI(__ intcon(0), arg));
1123     sign->init_req(1, __ intcon('-'));
1124     merge->init_req(2, __ IfFalse(iff));
1125     i->init_req(2, arg);
1126     sign->init_req(2, __ intcon(0));
1127 
1128     kit.set_control(merge);
1129 
1130     C->record_for_igvn(merge);
1131     C->record_for_igvn(i);
1132     C->record_for_igvn(sign);
1133   }
1134 
1135   // for (;;) {
1136   //     q = i / 10;
1137   //     r = i - ((q << 3) + (q << 1));  // r = i-(q*10) ...
1138   //     buf [--charPos] = digits [r];
1139   //     i = q;
1140   //     if (i == 0) break;
1141   // }
1142 
1143   {
1144     // Add loop predicate first.
1145     kit.add_predicate();
1146 
1147     RegionNode *head = new (C) RegionNode(3);
1148     head->init_req(1, kit.control());
1149     kit.gvn().set_type(head, Type::CONTROL);
1150     Node *i_phi = new (C) PhiNode(head, TypeInt::INT);
1151     i_phi->init_req(1, i);
1152     kit.gvn().set_type(i_phi, TypeInt::INT);
1153     charPos = PhiNode::make(head, charPos);
1154     kit.gvn().set_type(charPos, TypeInt::INT);
1155     Node *mem = PhiNode::make(head, kit.memory(char_adr_idx), Type::MEMORY, TypeAryPtr::CHARS);
1156     kit.gvn().set_type(mem, Type::MEMORY);
1157     kit.set_control(head);
1158     kit.set_memory(mem, char_adr_idx);
1159 
1160     Node* q = __ DivI(NULL, i_phi, __ intcon(10));
1161     Node* r = __ SubI(i_phi, __ AddI(__ LShiftI(q, __ intcon(3)),
1162                                      __ LShiftI(q, __ intcon(1))));
1163     Node* m1 = __ SubI(charPos, __ intcon(1));
1164     Node* ch = __ AddI(r, __ intcon('0'));
1165 
1166     Node* st = __ store_to_memory(kit.control(), kit.array_element_address(char_array, m1, T_CHAR),
1167                                   ch, T_CHAR, char_adr_idx);
1168 
1169 
1170     IfNode* iff = kit.create_and_map_if(head, __ Bool(__ CmpI(q, __ intcon(0)), BoolTest::ne),
1171                                         PROB_FAIR, COUNT_UNKNOWN);
1172     Node* ne = __ IfTrue(iff);
1173     Node* eq = __ IfFalse(iff);
1174 
1175     head->init_req(2, ne);
1176     mem->init_req(2, st);
1177     i_phi->init_req(2, q);
1178     charPos->init_req(2, m1);
1179 
1180     charPos = m1;
1181 
1182     kit.set_control(eq);
1183     kit.set_memory(st, char_adr_idx);
1184 
1185     C->record_for_igvn(head);
1186     C->record_for_igvn(mem);
1187     C->record_for_igvn(i_phi);
1188     C->record_for_igvn(charPos);
1189   }
1190 
1191   {
1192     // if (sign != 0) {
1193     //     buf [--charPos] = sign;
1194     // }
1195     IfNode* iff = kit.create_and_map_if(kit.control(),
1196                                         __ Bool(__ CmpI(sign, __ intcon(0)), BoolTest::ne),
1197                                         PROB_FAIR, COUNT_UNKNOWN);
1198 
1199     final_merge->init_req(2, __ IfFalse(iff));
1200     final_mem->init_req(2, kit.memory(char_adr_idx));
1201 
1202     kit.set_control(__ IfTrue(iff));
1203     if (kit.stopped()) {
1204       final_merge->init_req(1, C->top());
1205       final_mem->init_req(1, C->top());
1206     } else {
1207       Node* m1 = __ SubI(charPos, __ intcon(1));
1208       Node* st = __ store_to_memory(kit.control(), kit.array_element_address(char_array, m1, T_CHAR),
1209                                     sign, T_CHAR, char_adr_idx);
1210 
1211       final_merge->init_req(1, kit.control());
1212       final_mem->init_req(1, st);
1213     }
1214 
1215     kit.set_control(final_merge);
1216     kit.set_memory(final_mem, char_adr_idx);
1217 
1218     C->record_for_igvn(final_merge);
1219     C->record_for_igvn(final_mem);
1220   }
1221 }
1222 
1223 
1224 Node* PhaseStringOpts::copy_string(GraphKit& kit, Node* str, Node* char_array, Node* start) {
1225   Node* string = str;
1226   Node* offset = kit.load_String_offset(kit.control(), string);
1227   Node* count  = kit.load_String_length(kit.control(), string);
1228   Node* value  = kit.load_String_value (kit.control(), string);
1229 
1230   // copy the contents
1231   if (offset->is_Con() && count->is_Con() && value->is_Con() && count->get_int() < unroll_string_copy_length) {
1232     // For small constant strings just emit individual stores.
1233     // A length of 6 seems like a good space/speed tradeof.
1234     int c = count->get_int();
1235     int o = offset->get_int();
1236     const TypeOopPtr* t = kit.gvn().type(value)->isa_oopptr();
1237     ciTypeArray* value_array = t->const_oop()->as_type_array();
1238     for (int e = 0; e < c; e++) {
1239       __ store_to_memory(kit.control(), kit.array_element_address(char_array, start, T_CHAR),
1240                          __ intcon(value_array->char_at(o + e)), T_CHAR, char_adr_idx);
1241       start = __ AddI(start, __ intcon(1));
1242     }
1243   } else {
1244     Node* src_ptr = kit.array_element_address(value, offset, T_CHAR);
1245     Node* dst_ptr = kit.array_element_address(char_array, start, T_CHAR);
1246     Node* c = count;
1247     Node* extra = NULL;
1248 #ifdef _LP64
1249     c = __ ConvI2L(c);
1250     extra = C->top();
1251 #endif
1252     Node* call = kit.make_runtime_call(GraphKit::RC_LEAF|GraphKit::RC_NO_FP,
1253                                        OptoRuntime::fast_arraycopy_Type(),
1254                                        CAST_FROM_FN_PTR(address, StubRoutines::jshort_disjoint_arraycopy()),
1255                                        "jshort_disjoint_arraycopy", TypeAryPtr::CHARS,
1256                                        src_ptr, dst_ptr, c, extra);
1257     start = __ AddI(start, count);
1258   }
1259   return start;
1260 }
1261 
1262 
1263 void PhaseStringOpts::replace_string_concat(StringConcat* sc) {
1264   // Log a little info about the transformation
1265   sc->maybe_log_transform();
1266 
1267   // pull the JVMState of the allocation into a SafePointNode to serve as
1268   // as a shim for the insertion of the new code.
1269   JVMState* jvms     = sc->begin()->jvms()->clone_shallow(C);
1270   uint size = sc->begin()->req();
1271   SafePointNode* map = new (C) SafePointNode(size, jvms);
1272 
1273   // copy the control and memory state from the final call into our
1274   // new starting state.  This allows any preceeding tests to feed
1275   // into the new section of code.
1276   for (uint i1 = 0; i1 < TypeFunc::Parms; i1++) {
1277     map->init_req(i1, sc->end()->in(i1));
1278   }
1279   // blow away old allocation arguments
1280   for (uint i1 = TypeFunc::Parms; i1 < jvms->debug_start(); i1++) {
1281     map->init_req(i1, C->top());
1282   }
1283   // Copy the rest of the inputs for the JVMState
1284   for (uint i1 = jvms->debug_start(); i1 < sc->begin()->req(); i1++) {
1285     map->init_req(i1, sc->begin()->in(i1));
1286   }
1287   // Make sure the memory state is a MergeMem for parsing.
1288   if (!map->in(TypeFunc::Memory)->is_MergeMem()) {
1289     map->set_req(TypeFunc::Memory, MergeMemNode::make(C, map->in(TypeFunc::Memory)));
1290   }
1291 
1292   jvms->set_map(map);
1293   map->ensure_stack(jvms, jvms->method()->max_stack());
1294 
1295 
1296   // disconnect all the old StringBuilder calls from the graph
1297   sc->eliminate_unneeded_control();
1298 
1299   // At this point all the old work has been completely removed from
1300   // the graph and the saved JVMState exists at the point where the
1301   // final toString call used to be.
1302   GraphKit kit(jvms);
1303 
1304   // There may be uncommon traps which are still using the
1305   // intermediate states and these need to be rewritten to point at
1306   // the JVMState at the beginning of the transformation.
1307   sc->convert_uncommon_traps(kit, jvms);
1308 
1309   // Now insert the logic to compute the size of the string followed
1310   // by all the logic to construct array and resulting string.
1311 
1312   Node* null_string = __ makecon(TypeInstPtr::make(C->env()->the_null_string()));
1313 
1314   // Create a region for the overflow checks to merge into.
1315   int args = MAX2(sc->num_arguments(), 1);
1316   RegionNode* overflow = new (C) RegionNode(args);
1317   kit.gvn().set_type(overflow, Type::CONTROL);
1318 
1319   // Create a hook node to hold onto the individual sizes since they
1320   // are need for the copying phase.
1321   Node* string_sizes = new (C) Node(args);
1322 
1323   Node* length = __ intcon(0);
1324   for (int argi = 0; argi < sc->num_arguments(); argi++) {
1325     Node* arg = sc->argument(argi);
1326     switch (sc->mode(argi)) {
1327       case StringConcat::IntMode: {
1328         Node* string_size = int_stringSize(kit, arg);
1329 
1330         // accumulate total
1331         length = __ AddI(length, string_size);
1332 
1333         // Cache this value for the use by int_toString
1334         string_sizes->init_req(argi, string_size);
1335         break;
1336       }
1337       case StringConcat::StringNullCheckMode: {
1338         const Type* type = kit.gvn().type(arg);
1339         assert(type != TypePtr::NULL_PTR, "missing check");
1340         if (!type->higher_equal(TypeInstPtr::NOTNULL)) {
1341           // Null check with uncommont trap since
1342           // StringBuilder(null) throws exception.
1343           // Use special uncommon trap instead of
1344           // calling normal do_null_check().
1345           Node* p = __ Bool(__ CmpP(arg, kit.null()), BoolTest::ne);
1346           IfNode* iff = kit.create_and_map_if(kit.control(), p, PROB_MIN, COUNT_UNKNOWN);
1347           overflow->add_req(__ IfFalse(iff));
1348           Node* notnull = __ IfTrue(iff);
1349           kit.set_control(notnull); // set control for the cast_not_null
1350           arg = kit.cast_not_null(arg, false);
1351           sc->set_argument(argi, arg);
1352         }
1353         assert(kit.gvn().type(arg)->higher_equal(TypeInstPtr::NOTNULL), "sanity");
1354         // Fallthrough to add string length.
1355       }
1356       case StringConcat::StringMode: {
1357         const Type* type = kit.gvn().type(arg);
1358         if (type == TypePtr::NULL_PTR) {
1359           // replace the argument with the null checked version
1360           arg = null_string;
1361           sc->set_argument(argi, arg);
1362         } else if (!type->higher_equal(TypeInstPtr::NOTNULL)) {
1363           // s = s != null ? s : "null";
1364           // length = length + (s.count - s.offset);
1365           RegionNode *r = new (C) RegionNode(3);
1366           kit.gvn().set_type(r, Type::CONTROL);
1367           Node *phi = new (C) PhiNode(r, type);
1368           kit.gvn().set_type(phi, phi->bottom_type());
1369           Node* p = __ Bool(__ CmpP(arg, kit.null()), BoolTest::ne);
1370           IfNode* iff = kit.create_and_map_if(kit.control(), p, PROB_MIN, COUNT_UNKNOWN);
1371           Node* notnull = __ IfTrue(iff);
1372           Node* isnull =  __ IfFalse(iff);
1373           kit.set_control(notnull); // set control for the cast_not_null
1374           r->init_req(1, notnull);
1375           phi->init_req(1, kit.cast_not_null(arg, false));
1376           r->init_req(2, isnull);
1377           phi->init_req(2, null_string);
1378           kit.set_control(r);
1379           C->record_for_igvn(r);
1380           C->record_for_igvn(phi);
1381           // replace the argument with the null checked version
1382           arg = phi;
1383           sc->set_argument(argi, arg);
1384         }
1385 
1386         Node* count = kit.load_String_length(kit.control(), arg);
1387 
1388         length = __ AddI(length, count);
1389         string_sizes->init_req(argi, NULL);
1390         break;
1391       }
1392       case StringConcat::CharMode: {
1393         // one character only
1394         length = __ AddI(length, __ intcon(1));
1395         break;
1396       }
1397       default:
1398         ShouldNotReachHere();
1399     }
1400     if (argi > 0) {
1401       // Check that the sum hasn't overflowed
1402       IfNode* iff = kit.create_and_map_if(kit.control(),
1403                                           __ Bool(__ CmpI(length, __ intcon(0)), BoolTest::lt),
1404                                           PROB_MIN, COUNT_UNKNOWN);
1405       kit.set_control(__ IfFalse(iff));
1406       overflow->set_req(argi, __ IfTrue(iff));
1407     }
1408   }
1409 
1410   {
1411     // Hook
1412     PreserveJVMState pjvms(&kit);
1413     kit.set_control(overflow);
1414     C->record_for_igvn(overflow);
1415     kit.uncommon_trap(Deoptimization::Reason_intrinsic,
1416                       Deoptimization::Action_make_not_entrant);
1417   }
1418 
1419   Node* result;
1420   if (!kit.stopped()) {
1421 
1422     // length now contains the number of characters needed for the
1423     // char[] so create a new AllocateArray for the char[]
1424     Node* char_array = NULL;
1425     {
1426       PreserveReexecuteState preexecs(&kit);
1427       // The original jvms is for an allocation of either a String or
1428       // StringBuffer so no stack adjustment is necessary for proper
1429       // reexecution.  If we deoptimize in the slow path the bytecode
1430       // will be reexecuted and the char[] allocation will be thrown away.
1431       kit.jvms()->set_should_reexecute(true);
1432       char_array = kit.new_array(__ makecon(TypeKlassPtr::make(ciTypeArrayKlass::make(T_CHAR))),
1433                                  length, 1);
1434     }
1435 
1436     // Mark the allocation so that zeroing is skipped since the code
1437     // below will overwrite the entire array
1438     AllocateArrayNode* char_alloc = AllocateArrayNode::Ideal_array_allocation(char_array, _gvn);
1439     char_alloc->maybe_set_complete(_gvn);
1440 
1441     // Now copy the string representations into the final char[]
1442     Node* start = __ intcon(0);
1443     for (int argi = 0; argi < sc->num_arguments(); argi++) {
1444       Node* arg = sc->argument(argi);
1445       switch (sc->mode(argi)) {
1446         case StringConcat::IntMode: {
1447           Node* end = __ AddI(start, string_sizes->in(argi));
1448           // getChars words backwards so pass the ending point as well as the start
1449           int_getChars(kit, arg, char_array, start, end);
1450           start = end;
1451           break;
1452         }
1453         case StringConcat::StringNullCheckMode:
1454         case StringConcat::StringMode: {
1455           start = copy_string(kit, arg, char_array, start);
1456           break;
1457         }
1458         case StringConcat::CharMode: {
1459           __ store_to_memory(kit.control(), kit.array_element_address(char_array, start, T_CHAR),
1460                              arg, T_CHAR, char_adr_idx);
1461           start = __ AddI(start, __ intcon(1));
1462           break;
1463         }
1464         default:
1465           ShouldNotReachHere();
1466       }
1467     }
1468 
1469     // If we're not reusing an existing String allocation then allocate one here.
1470     result = sc->string_alloc();
1471     if (result == NULL) {
1472       PreserveReexecuteState preexecs(&kit);
1473       // The original jvms is for an allocation of either a String or
1474       // StringBuffer so no stack adjustment is necessary for proper
1475       // reexecution.
1476       kit.jvms()->set_should_reexecute(true);
1477       result = kit.new_instance(__ makecon(TypeKlassPtr::make(C->env()->String_klass())));
1478     }
1479 
1480     // Intialize the string
1481     if (java_lang_String::has_offset_field()) {
1482       kit.store_String_offset(kit.control(), result, __ intcon(0));
1483       kit.store_String_length(kit.control(), result, length);
1484     }
1485     kit.store_String_value(kit.control(), result, char_array);
1486   } else {
1487     result = C->top();
1488   }
1489   // hook up the outgoing control and result
1490   kit.replace_call(sc->end(), result);
1491 
1492   // Unhook any hook nodes
1493   string_sizes->disconnect_inputs(NULL, C);
1494   sc->cleanup();
1495 }
--- EOF ---