1 /*
   2  * Copyright (c) 2009, 2020, 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 "ci/ciSymbols.hpp"
  27 #include "classfile/javaClasses.hpp"
  28 #include "compiler/compileLog.hpp"
  29 #include "opto/addnode.hpp"
  30 #include "opto/callGenerator.hpp"
  31 #include "opto/callnode.hpp"
  32 #include "opto/divnode.hpp"
  33 #include "opto/graphKit.hpp"
  34 #include "opto/idealKit.hpp"
  35 #include "opto/rootnode.hpp"
  36 #include "opto/runtime.hpp"
  37 #include "opto/stringopts.hpp"
  38 #include "opto/subnode.hpp"
  39 #include "runtime/sharedRuntime.hpp"
  40 #include "runtime/stubRoutines.hpp"
  41 
  42 #define __ kit.
  43 
  44 class StringConcat : public ResourceObj {
  45  private:
  46   PhaseStringOpts*    _stringopts;
  47   Node*               _string_alloc;
  48   AllocateNode*       _begin;          // The allocation the begins the pattern
  49   CallStaticJavaNode* _end;            // The final call of the pattern.  Will either be
  50                                        // SB.toString or or String.<init>(SB.toString)
  51   bool                _multiple;       // indicates this is a fusion of two or more
  52                                        // separate StringBuilders
  53 
  54   Node*               _arguments;      // The list of arguments to be concatenated
  55   GrowableArray<int>  _mode;           // into a String along with a mode flag
  56                                        // indicating how to treat the value.
  57   Node_List           _constructors;   // List of constructors (many in case of stacked concat)
  58   Node_List           _control;        // List of control nodes that will be deleted
  59   Node_List           _uncommon_traps; // Uncommon traps that needs to be rewritten
  60                                        // to restart at the initial JVMState.
  61 
  62  public:
  63   // Mode for converting arguments to Strings
  64   enum {
  65     StringMode,
  66     IntMode,
  67     CharMode,
  68     StringNullCheckMode,
  69     NegativeIntCheckMode
  70   };
  71 
  72   StringConcat(PhaseStringOpts* stringopts, CallStaticJavaNode* end):
  73     _stringopts(stringopts),
  74     _string_alloc(NULL),
  75     _begin(NULL),
  76     _end(end),
  77     _multiple(false) {
  78     _arguments = new Node(1);
  79     _arguments->del_req(0);
  80   }
  81 
  82   bool validate_mem_flow();
  83   bool validate_control_flow();
  84 
  85   void merge_add() {
  86 #if 0
  87     // XXX This is place holder code for reusing an existing String
  88     // allocation but the logic for checking the state safety is
  89     // probably inadequate at the moment.
  90     CallProjections endprojs;
  91     sc->end()->extract_projections(&endprojs, false);
  92     if (endprojs.resproj != NULL) {
  93       for (SimpleDUIterator i(endprojs.resproj); i.has_next(); i.next()) {
  94         CallStaticJavaNode *use = i.get()->isa_CallStaticJava();
  95         if (use != NULL && use->method() != NULL &&
  96             use->method()->intrinsic_id() == vmIntrinsics::_String_String &&
  97             use->in(TypeFunc::Parms + 1) == endprojs.resproj) {
  98           // Found useless new String(sb.toString()) so reuse the newly allocated String
  99           // when creating the result instead of allocating a new one.
 100           sc->set_string_alloc(use->in(TypeFunc::Parms));
 101           sc->set_end(use);
 102         }
 103       }
 104     }
 105 #endif
 106   }
 107 
 108   StringConcat* merge(StringConcat* other, Node* arg);
 109 
 110   void set_allocation(AllocateNode* alloc) {
 111     _begin = alloc;
 112   }
 113 
 114   void append(Node* value, int mode) {
 115     _arguments->add_req(value);
 116     _mode.append(mode);
 117   }
 118   void push(Node* value, int mode) {
 119     _arguments->ins_req(0, value);
 120     _mode.insert_before(0, mode);
 121   }
 122 
 123   void push_string(Node* value) {
 124     push(value, StringMode);
 125   }
 126 
 127   void push_string_null_check(Node* value) {
 128     push(value, StringNullCheckMode);
 129   }
 130 
 131   void push_negative_int_check(Node* value) {
 132     push(value, NegativeIntCheckMode);
 133   }
 134 
 135   void push_int(Node* value) {
 136     push(value, IntMode);
 137   }
 138 
 139   void push_char(Node* value) {
 140     push(value, CharMode);
 141   }
 142 
 143   static bool is_SB_toString(Node* call) {
 144     if (call->is_CallStaticJava()) {
 145       CallStaticJavaNode* csj = call->as_CallStaticJava();
 146       ciMethod* m = csj->method();
 147       if (m != NULL &&
 148           (m->intrinsic_id() == vmIntrinsics::_StringBuilder_toString ||
 149            m->intrinsic_id() == vmIntrinsics::_StringBuffer_toString)) {
 150         return true;
 151       }
 152     }
 153     return false;
 154   }
 155 
 156   static Node* skip_string_null_check(Node* value) {
 157     // Look for a diamond shaped Null check of toString() result
 158     // (could be code from String.valueOf()):
 159     // (Proj == NULL) ? "null":"CastPP(Proj)#NotNULL
 160     if (value->is_Phi()) {
 161       int true_path = value->as_Phi()->is_diamond_phi();
 162       if (true_path != 0) {
 163         // phi->region->if_proj->ifnode->bool
 164         BoolNode* b = value->in(0)->in(1)->in(0)->in(1)->as_Bool();
 165         Node* cmp = b->in(1);
 166         Node* v1 = cmp->in(1);
 167         Node* v2 = cmp->in(2);
 168         // Null check of the return of toString which can simply be skipped.
 169         if (b->_test._test == BoolTest::ne &&
 170             v2->bottom_type() == TypePtr::NULL_PTR &&
 171             value->in(true_path)->Opcode() == Op_CastPP &&
 172             value->in(true_path)->in(1) == v1 &&
 173             v1->is_Proj() && is_SB_toString(v1->in(0))) {
 174           return v1;
 175         }
 176       }
 177     }
 178     return value;
 179   }
 180 
 181   Node* argument(int i) {
 182     return _arguments->in(i);
 183   }
 184   Node* argument_uncast(int i) {
 185     Node* arg = argument(i);
 186     int amode = mode(i);
 187     if (amode == StringConcat::StringMode ||
 188         amode == StringConcat::StringNullCheckMode) {
 189       arg = skip_string_null_check(arg);
 190     }
 191     return arg;
 192   }
 193   void set_argument(int i, Node* value) {
 194     _arguments->set_req(i, value);
 195   }
 196   int num_arguments() {
 197     return _mode.length();
 198   }
 199   int mode(int i) {
 200     return _mode.at(i);
 201   }
 202   void add_control(Node* ctrl) {
 203     assert(!_control.contains(ctrl), "only push once");
 204     _control.push(ctrl);
 205   }
 206   void add_constructor(Node* init) {
 207     assert(!_constructors.contains(init), "only push once");
 208     _constructors.push(init);
 209   }
 210   CallStaticJavaNode* end() { return _end; }
 211   AllocateNode* begin() { return _begin; }
 212   Node* string_alloc() { return _string_alloc; }
 213 
 214   void eliminate_unneeded_control();
 215   void eliminate_initialize(InitializeNode* init);
 216   void eliminate_call(CallNode* call);
 217 
 218   void maybe_log_transform() {
 219     CompileLog* log = _stringopts->C->log();
 220     if (log != NULL) {
 221       log->head("replace_string_concat arguments='%d' string_alloc='%d' multiple='%d'",
 222                 num_arguments(),
 223                 _string_alloc != NULL,
 224                 _multiple);
 225       JVMState* p = _begin->jvms();
 226       while (p != NULL) {
 227         log->elem("jvms bci='%d' method='%d'", p->bci(), log->identify(p->method()));
 228         p = p->caller();
 229       }
 230       log->tail("replace_string_concat");
 231     }
 232   }
 233 
 234   void convert_uncommon_traps(GraphKit& kit, const JVMState* jvms) {
 235     for (uint u = 0; u < _uncommon_traps.size(); u++) {
 236       Node* uct = _uncommon_traps.at(u);
 237 
 238       // Build a new call using the jvms state of the allocate
 239       address call_addr = SharedRuntime::uncommon_trap_blob()->entry_point();
 240       const TypeFunc* call_type = OptoRuntime::uncommon_trap_Type();
 241       const TypePtr* no_memory_effects = NULL;
 242       Compile* C = _stringopts->C;
 243       CallStaticJavaNode* call = new CallStaticJavaNode(call_type, call_addr, "uncommon_trap",
 244                                                         no_memory_effects);
 245       for (int e = 0; e < TypeFunc::Parms; e++) {
 246         call->init_req(e, uct->in(e));
 247       }
 248       // Set the trap request to record intrinsic failure if this trap
 249       // is taken too many times.  Ideally we would handle then traps by
 250       // doing the original bookkeeping in the MDO so that if it caused
 251       // the code to be thrown out we could still recompile and use the
 252       // optimization.  Failing the uncommon traps doesn't really mean
 253       // that the optimization is a bad idea but there's no other way to
 254       // do the MDO updates currently.
 255       int trap_request = Deoptimization::make_trap_request(Deoptimization::Reason_intrinsic,
 256                                                            Deoptimization::Action_make_not_entrant);
 257       call->init_req(TypeFunc::Parms, __ intcon(trap_request));
 258       kit.add_safepoint_edges(call);
 259 
 260       _stringopts->gvn()->transform(call);
 261       C->gvn_replace_by(uct, call);
 262       uct->disconnect_inputs(C);
 263     }
 264   }
 265 
 266   void cleanup() {
 267     // disconnect the hook node
 268     _arguments->disconnect_inputs(_stringopts->C);
 269   }
 270 };
 271 
 272 
 273 void StringConcat::eliminate_unneeded_control() {
 274   for (uint i = 0; i < _control.size(); i++) {
 275     Node* n = _control.at(i);
 276     if (n->is_Allocate()) {
 277       eliminate_initialize(n->as_Allocate()->initialization());
 278     }
 279     if (n->is_Call()) {
 280       if (n != _end) {
 281         eliminate_call(n->as_Call());
 282       }
 283     } else if (n->is_IfTrue()) {
 284       Compile* C = _stringopts->C;
 285       C->gvn_replace_by(n, n->in(0)->in(0));
 286       // get rid of the other projection
 287       C->gvn_replace_by(n->in(0)->as_If()->proj_out(false), C->top());
 288     } else if (n->is_Region()) {
 289       Node* iff = n->in(1)->in(0);
 290       assert(n->req() == 3 && n->in(2)->in(0) == iff, "not a diamond");
 291       assert(iff->is_If(), "no if for the diamond");
 292       Node* bol = iff->in(1);
 293       assert(bol->is_Bool(), "unexpected if shape");
 294       Node* cmp = bol->in(1);
 295       assert(cmp->is_Cmp(), "unexpected if shape");
 296       if (cmp->in(1)->is_top() || cmp->in(2)->is_top()) {
 297         // This region should lose its Phis and be optimized out by igvn but there's a chance the if folds to top first
 298         // which then causes a reachable part of the graph to become dead.
 299         Compile* C = _stringopts->C;
 300         C->gvn_replace_by(n, iff->in(0));
 301       }
 302     }
 303   }
 304 }
 305 
 306 
 307 StringConcat* StringConcat::merge(StringConcat* other, Node* arg) {
 308   StringConcat* result = new StringConcat(_stringopts, _end);
 309   for (uint x = 0; x < _control.size(); x++) {
 310     Node* n = _control.at(x);
 311     if (n->is_Call()) {
 312       result->_control.push(n);
 313     }
 314   }
 315   for (uint x = 0; x < other->_control.size(); x++) {
 316     Node* n = other->_control.at(x);
 317     if (n->is_Call()) {
 318       result->_control.push(n);
 319     }
 320   }
 321   assert(result->_control.contains(other->_end), "what?");
 322   assert(result->_control.contains(_begin), "what?");
 323   for (int x = 0; x < num_arguments(); x++) {
 324     Node* argx = argument_uncast(x);
 325     if (argx == arg) {
 326       // replace the toString result with the all the arguments that
 327       // made up the other StringConcat
 328       for (int y = 0; y < other->num_arguments(); y++) {
 329         result->append(other->argument(y), other->mode(y));
 330       }
 331     } else {
 332       result->append(argx, mode(x));
 333     }
 334   }
 335   result->set_allocation(other->_begin);
 336   for (uint i = 0; i < _constructors.size(); i++) {
 337     result->add_constructor(_constructors.at(i));
 338   }
 339   for (uint i = 0; i < other->_constructors.size(); i++) {
 340     result->add_constructor(other->_constructors.at(i));
 341   }
 342   result->_multiple = true;
 343   return result;
 344 }
 345 
 346 
 347 void StringConcat::eliminate_call(CallNode* call) {
 348   Compile* C = _stringopts->C;
 349   CallProjections* projs = call->extract_projections(false);
 350   if (projs->fallthrough_catchproj != NULL) {
 351     C->gvn_replace_by(projs->fallthrough_catchproj, call->in(TypeFunc::Control));
 352   }
 353   if (projs->fallthrough_memproj != NULL) {
 354     C->gvn_replace_by(projs->fallthrough_memproj, call->in(TypeFunc::Memory));
 355   }
 356   if (projs->catchall_memproj != NULL) {
 357     C->gvn_replace_by(projs->catchall_memproj, C->top());
 358   }
 359   if (projs->fallthrough_ioproj != NULL) {
 360     C->gvn_replace_by(projs->fallthrough_ioproj, call->in(TypeFunc::I_O));
 361   }
 362   if (projs->catchall_ioproj != NULL) {
 363     C->gvn_replace_by(projs->catchall_ioproj, C->top());
 364   }
 365   if (projs->catchall_catchproj != NULL) {
 366     // EA can't cope with the partially collapsed graph this
 367     // creates so put it on the worklist to be collapsed later.
 368     for (SimpleDUIterator i(projs->catchall_catchproj); i.has_next(); i.next()) {
 369       Node *use = i.get();
 370       int opc = use->Opcode();
 371       if (opc == Op_CreateEx || opc == Op_Region) {
 372         _stringopts->record_dead_node(use);
 373       }
 374     }
 375     C->gvn_replace_by(projs->catchall_catchproj, C->top());
 376   }
 377   if (projs->resproj[0] != NULL) {
 378     assert(projs->nb_resproj == 1, "unexpected number of results");
 379     C->gvn_replace_by(projs->resproj[0], C->top());
 380   }
 381   C->gvn_replace_by(call, C->top());
 382 }
 383 
 384 void StringConcat::eliminate_initialize(InitializeNode* init) {
 385   Compile* C = _stringopts->C;
 386 
 387   // Eliminate Initialize node.
 388   assert(init->outcnt() <= 2, "only a control and memory projection expected");
 389   assert(init->req() <= InitializeNode::RawStores, "no pending inits");
 390   Node *ctrl_proj = init->proj_out_or_null(TypeFunc::Control);
 391   if (ctrl_proj != NULL) {
 392     C->gvn_replace_by(ctrl_proj, init->in(TypeFunc::Control));
 393   }
 394   Node *mem_proj = init->proj_out_or_null(TypeFunc::Memory);
 395   if (mem_proj != NULL) {
 396     Node *mem = init->in(TypeFunc::Memory);
 397     C->gvn_replace_by(mem_proj, mem);
 398   }
 399   C->gvn_replace_by(init, C->top());
 400   init->disconnect_inputs(C);
 401 }
 402 
 403 Node_List PhaseStringOpts::collect_toString_calls() {
 404   Node_List string_calls;
 405   Node_List worklist;
 406 
 407   _visited.clear();
 408 
 409   // Prime the worklist
 410   for (uint i = 1; i < C->root()->len(); i++) {
 411     Node* n = C->root()->in(i);
 412     if (n != NULL && !_visited.test_set(n->_idx)) {
 413       worklist.push(n);
 414     }
 415   }
 416 
 417   while (worklist.size() > 0) {
 418     Node* ctrl = worklist.pop();
 419     if (StringConcat::is_SB_toString(ctrl)) {
 420       CallStaticJavaNode* csj = ctrl->as_CallStaticJava();
 421       string_calls.push(csj);
 422     }
 423     if (ctrl->in(0) != NULL && !_visited.test_set(ctrl->in(0)->_idx)) {
 424       worklist.push(ctrl->in(0));
 425     }
 426     if (ctrl->is_Region()) {
 427       for (uint i = 1; i < ctrl->len(); i++) {
 428         if (ctrl->in(i) != NULL && !_visited.test_set(ctrl->in(i)->_idx)) {
 429           worklist.push(ctrl->in(i));
 430         }
 431       }
 432     }
 433   }
 434   return string_calls;
 435 }
 436 
 437 
 438 StringConcat* PhaseStringOpts::build_candidate(CallStaticJavaNode* call) {
 439   ciMethod* m = call->method();
 440   ciSymbol* string_sig;
 441   ciSymbol* int_sig;
 442   ciSymbol* char_sig;
 443   if (m->holder() == C->env()->StringBuilder_klass()) {
 444     string_sig = ciSymbols::String_StringBuilder_signature();
 445     int_sig = ciSymbols::int_StringBuilder_signature();
 446     char_sig = ciSymbols::char_StringBuilder_signature();
 447   } else if (m->holder() == C->env()->StringBuffer_klass()) {
 448     string_sig = ciSymbols::String_StringBuffer_signature();
 449     int_sig = ciSymbols::int_StringBuffer_signature();
 450     char_sig = ciSymbols::char_StringBuffer_signature();
 451   } else {
 452     return NULL;
 453   }
 454 #ifndef PRODUCT
 455   if (PrintOptimizeStringConcat) {
 456     tty->print("considering toString call in ");
 457     call->jvms()->dump_spec(tty); tty->cr();
 458   }
 459 #endif
 460 
 461   StringConcat* sc = new StringConcat(this, call);
 462 
 463   AllocateNode* alloc = NULL;
 464   InitializeNode* init = NULL;
 465 
 466   // possible opportunity for StringBuilder fusion
 467   CallStaticJavaNode* cnode = call;
 468   while (cnode) {
 469     Node* recv = cnode->in(TypeFunc::Parms)->uncast();
 470     if (recv->is_Proj()) {
 471       recv = recv->in(0);
 472     }
 473     cnode = recv->isa_CallStaticJava();
 474     if (cnode == NULL) {
 475       alloc = recv->isa_Allocate();
 476       if (alloc == NULL) {
 477         break;
 478       }
 479       // Find the constructor call
 480       Node* result = alloc->result_cast();
 481       if (result == NULL || !result->is_CheckCastPP() || alloc->in(TypeFunc::Memory)->is_top()) {
 482         // strange looking allocation
 483 #ifndef PRODUCT
 484         if (PrintOptimizeStringConcat) {
 485           tty->print("giving up because allocation looks strange ");
 486           alloc->jvms()->dump_spec(tty); tty->cr();
 487         }
 488 #endif
 489         break;
 490       }
 491       Node* constructor = NULL;
 492       for (SimpleDUIterator i(result); i.has_next(); i.next()) {
 493         CallStaticJavaNode *use = i.get()->isa_CallStaticJava();
 494         if (use != NULL &&
 495             use->method() != NULL &&
 496             !use->method()->is_static() &&
 497             use->method()->name() == ciSymbols::object_initializer_name() &&
 498             use->method()->holder() == m->holder()) {
 499           // Matched the constructor.
 500           ciSymbol* sig = use->method()->signature()->as_symbol();
 501           if (sig == ciSymbols::void_method_signature() ||
 502               sig == ciSymbols::int_void_signature() ||
 503               sig == ciSymbols::string_void_signature()) {
 504             if (sig == ciSymbols::string_void_signature()) {
 505               // StringBuilder(String) so pick this up as the first argument
 506               assert(use->in(TypeFunc::Parms + 1) != NULL, "what?");
 507               const Type* type = _gvn->type(use->in(TypeFunc::Parms + 1));
 508               if (type == TypePtr::NULL_PTR) {
 509                 // StringBuilder(null) throws exception.
 510 #ifndef PRODUCT
 511                 if (PrintOptimizeStringConcat) {
 512                   tty->print("giving up because StringBuilder(null) throws exception");
 513                   alloc->jvms()->dump_spec(tty);
 514                   tty->cr();
 515                 }
 516 #endif
 517                 return NULL;
 518               }
 519               // StringBuilder(str) argument needs null check.
 520               sc->push_string_null_check(use->in(TypeFunc::Parms + 1));
 521             } else if (sig == ciSymbols::int_void_signature()) {
 522               // StringBuilder(int) case.
 523               Node* parm = use->in(TypeFunc::Parms + 1);
 524               assert(parm != NULL, "must exist");
 525               const TypeInt* type = _gvn->type(parm)->is_int();
 526               if (type->_hi < 0) {
 527                 // Initial capacity argument is always negative in which case StringBuilder(int) throws
 528                 // a NegativeArraySizeException. Bail out from string opts.
 529 #ifndef PRODUCT
 530                 if (PrintOptimizeStringConcat) {
 531                   tty->print("giving up because a negative argument is passed to StringBuilder(int) which "
 532                              "throws a NegativeArraySizeException");
 533                   alloc->jvms()->dump_spec(tty);
 534                   tty->cr();
 535                 }
 536 #endif
 537                 return NULL;
 538               } else if (type->_lo < 0) {
 539                 // Argument could be negative: We need a runtime check to throw NegativeArraySizeException in that case.
 540                 sc->push_negative_int_check(parm);
 541               }
 542             }
 543             // The int variant takes an initial size for the backing
 544             // array so just treat it like the void version.
 545             constructor = use;
 546           } else {
 547 #ifndef PRODUCT
 548             if (PrintOptimizeStringConcat) {
 549               tty->print("unexpected constructor signature: %s", sig->as_utf8());
 550             }
 551 #endif
 552           }
 553           break;
 554         }
 555       }
 556       if (constructor == NULL) {
 557         // couldn't find constructor
 558 #ifndef PRODUCT
 559         if (PrintOptimizeStringConcat) {
 560           tty->print("giving up because couldn't find constructor ");
 561           alloc->jvms()->dump_spec(tty); tty->cr();
 562         }
 563 #endif
 564         break;
 565       }
 566 
 567       // Walked all the way back and found the constructor call so see
 568       // if this call converted into a direct string concatenation.
 569       sc->add_control(call);
 570       sc->add_control(constructor);
 571       sc->add_control(alloc);
 572       sc->set_allocation(alloc);
 573       sc->add_constructor(constructor);
 574       if (sc->validate_control_flow() && sc->validate_mem_flow()) {
 575         return sc;
 576       } else {
 577         return NULL;
 578       }
 579     } else if (cnode->method() == NULL) {
 580       break;
 581     } else if (!cnode->method()->is_static() &&
 582                cnode->method()->holder() == m->holder() &&
 583                cnode->method()->name() == ciSymbols::append_name() &&
 584                (cnode->method()->signature()->as_symbol() == string_sig ||
 585                 cnode->method()->signature()->as_symbol() == char_sig ||
 586                 cnode->method()->signature()->as_symbol() == int_sig)) {
 587       sc->add_control(cnode);
 588       Node* arg = cnode->in(TypeFunc::Parms + 1);
 589       if (arg == NULL || arg->is_top()) {
 590 #ifndef PRODUCT
 591         if (PrintOptimizeStringConcat) {
 592           tty->print("giving up because the call is effectively dead");
 593           cnode->jvms()->dump_spec(tty); tty->cr();
 594         }
 595 #endif
 596         break;
 597       }
 598       if (cnode->method()->signature()->as_symbol() == int_sig) {
 599         sc->push_int(arg);
 600       } else if (cnode->method()->signature()->as_symbol() == char_sig) {
 601         sc->push_char(arg);
 602       } else {
 603         if (arg->is_Proj() && arg->in(0)->is_CallStaticJava()) {
 604           CallStaticJavaNode* csj = arg->in(0)->as_CallStaticJava();
 605           if (csj->method() != NULL &&
 606               csj->method()->intrinsic_id() == vmIntrinsics::_Integer_toString &&
 607               arg->outcnt() == 1) {
 608             // _control is the list of StringBuilder calls nodes which
 609             // will be replaced by new String code after this optimization.
 610             // Integer::toString() call is not part of StringBuilder calls
 611             // chain. It could be eliminated only if its result is used
 612             // only by this SB calls chain.
 613             // Another limitation: it should be used only once because
 614             // it is unknown that it is used only by this SB calls chain
 615             // until all related SB calls nodes are collected.
 616             assert(arg->unique_out() == cnode, "sanity");
 617             sc->add_control(csj);
 618             sc->push_int(csj->in(TypeFunc::Parms));
 619             continue;
 620           }
 621         }
 622         sc->push_string(arg);
 623       }
 624       continue;
 625     } else {
 626       // some unhandled signature
 627 #ifndef PRODUCT
 628       if (PrintOptimizeStringConcat) {
 629         tty->print("giving up because encountered unexpected signature ");
 630         cnode->tf()->dump(); tty->cr();
 631         cnode->in(TypeFunc::Parms + 1)->dump();
 632       }
 633 #endif
 634       break;
 635     }
 636   }
 637   return NULL;
 638 }
 639 
 640 
 641 PhaseStringOpts::PhaseStringOpts(PhaseGVN* gvn, Unique_Node_List*):
 642   Phase(StringOpts),
 643   _gvn(gvn) {
 644 
 645   assert(OptimizeStringConcat, "shouldn't be here");
 646 
 647   size_table_field = C->env()->Integer_klass()->get_field_by_name(ciSymbol::make("sizeTable"),
 648                                                                   ciSymbols::int_array_signature(), true);
 649   if (size_table_field == NULL) {
 650     // Something wrong so give up.
 651     assert(false, "why can't we find Integer.sizeTable?");
 652     return;
 653   }
 654 
 655   // Collect the types needed to talk about the various slices of memory
 656   byte_adr_idx = C->get_alias_index(TypeAryPtr::BYTES);
 657 
 658   // For each locally allocated StringBuffer see if the usages can be
 659   // collapsed into a single String construction.
 660 
 661   // Run through the list of allocation looking for SB.toString to see
 662   // if it's possible to fuse the usage of the SB into a single String
 663   // construction.
 664   GrowableArray<StringConcat*> concats;
 665   Node_List toStrings = collect_toString_calls();
 666   while (toStrings.size() > 0) {
 667     StringConcat* sc = build_candidate(toStrings.pop()->as_CallStaticJava());
 668     if (sc != NULL) {
 669       concats.push(sc);
 670     }
 671   }
 672 
 673   // try to coalesce separate concats
 674  restart:
 675   for (int c = 0; c < concats.length(); c++) {
 676     StringConcat* sc = concats.at(c);
 677     for (int i = 0; i < sc->num_arguments(); i++) {
 678       Node* arg = sc->argument_uncast(i);
 679       if (arg->is_Proj() && StringConcat::is_SB_toString(arg->in(0))) {
 680         CallStaticJavaNode* csj = arg->in(0)->as_CallStaticJava();
 681         for (int o = 0; o < concats.length(); o++) {
 682           if (c == o) continue;
 683           StringConcat* other = concats.at(o);
 684           if (other->end() == csj) {
 685 #ifndef PRODUCT
 686             if (PrintOptimizeStringConcat) {
 687               tty->print_cr("considering stacked concats");
 688             }
 689 #endif
 690 
 691             StringConcat* merged = sc->merge(other, arg);
 692             if (merged->validate_control_flow() && merged->validate_mem_flow()) {
 693 #ifndef PRODUCT
 694               if (PrintOptimizeStringConcat) {
 695                 tty->print_cr("stacking would succeed");
 696               }
 697 #endif
 698               if (c < o) {
 699                 concats.remove_at(o);
 700                 concats.at_put(c, merged);
 701               } else {
 702                 concats.remove_at(c);
 703                 concats.at_put(o, merged);
 704               }
 705               goto restart;
 706             } else {
 707 #ifndef PRODUCT
 708               if (PrintOptimizeStringConcat) {
 709                 tty->print_cr("stacking would fail");
 710               }
 711 #endif
 712             }
 713           }
 714         }
 715       }
 716     }
 717   }
 718 
 719 
 720   for (int c = 0; c < concats.length(); c++) {
 721     StringConcat* sc = concats.at(c);
 722     replace_string_concat(sc);
 723   }
 724 
 725   remove_dead_nodes();
 726 }
 727 
 728 void PhaseStringOpts::record_dead_node(Node* dead) {
 729   dead_worklist.push(dead);
 730 }
 731 
 732 void PhaseStringOpts::remove_dead_nodes() {
 733   // Delete any dead nodes to make things clean enough that escape
 734   // analysis doesn't get unhappy.
 735   while (dead_worklist.size() > 0) {
 736     Node* use = dead_worklist.pop();
 737     int opc = use->Opcode();
 738     switch (opc) {
 739       case Op_Region: {
 740         uint i = 1;
 741         for (i = 1; i < use->req(); i++) {
 742           if (use->in(i) != C->top()) {
 743             break;
 744           }
 745         }
 746         if (i >= use->req()) {
 747           for (SimpleDUIterator i(use); i.has_next(); i.next()) {
 748             Node* m = i.get();
 749             if (m->is_Phi()) {
 750               dead_worklist.push(m);
 751             }
 752           }
 753           C->gvn_replace_by(use, C->top());
 754         }
 755         break;
 756       }
 757       case Op_AddP:
 758       case Op_CreateEx: {
 759         // Recurisvely clean up references to CreateEx so EA doesn't
 760         // get unhappy about the partially collapsed graph.
 761         for (SimpleDUIterator i(use); i.has_next(); i.next()) {
 762           Node* m = i.get();
 763           if (m->is_AddP()) {
 764             dead_worklist.push(m);
 765           }
 766         }
 767         C->gvn_replace_by(use, C->top());
 768         break;
 769       }
 770       case Op_Phi:
 771         if (use->in(0) == C->top()) {
 772           C->gvn_replace_by(use, C->top());
 773         }
 774         break;
 775     }
 776   }
 777 }
 778 
 779 
 780 bool StringConcat::validate_mem_flow() {
 781   Compile* C = _stringopts->C;
 782 
 783   for (uint i = 0; i < _control.size(); i++) {
 784 #ifndef PRODUCT
 785     Node_List path;
 786 #endif
 787     Node* curr = _control.at(i);
 788     if (curr->is_Call() && curr != _begin) { // For all calls except the first allocation
 789       // Now here's the main invariant in our case:
 790       // For memory between the constructor, and appends, and toString we should only see bottom memory,
 791       // produced by the previous call we know about.
 792       if (!_constructors.contains(curr)) {
 793         NOT_PRODUCT(path.push(curr);)
 794         Node* mem = curr->in(TypeFunc::Memory);
 795         assert(mem != NULL, "calls should have memory edge");
 796         assert(!mem->is_Phi(), "should be handled by control flow validation");
 797         NOT_PRODUCT(path.push(mem);)
 798         while (mem->is_MergeMem()) {
 799           for (uint i = 1; i < mem->req(); i++) {
 800             if (i != Compile::AliasIdxBot && mem->in(i) != C->top()) {
 801 #ifndef PRODUCT
 802               if (PrintOptimizeStringConcat) {
 803                 tty->print("fusion has incorrect memory flow (side effects) for ");
 804                 _begin->jvms()->dump_spec(tty); tty->cr();
 805                 path.dump();
 806               }
 807 #endif
 808               return false;
 809             }
 810           }
 811           // skip through a potential MergeMem chain, linked through Bot
 812           mem = mem->in(Compile::AliasIdxBot);
 813           NOT_PRODUCT(path.push(mem);)
 814         }
 815         // now let it fall through, and see if we have a projection
 816         if (mem->is_Proj()) {
 817           // Should point to a previous known call
 818           Node *prev = mem->in(0);
 819           NOT_PRODUCT(path.push(prev);)
 820           if (!prev->is_Call() || !_control.contains(prev)) {
 821 #ifndef PRODUCT
 822             if (PrintOptimizeStringConcat) {
 823               tty->print("fusion has incorrect memory flow (unknown call) for ");
 824               _begin->jvms()->dump_spec(tty); tty->cr();
 825               path.dump();
 826             }
 827 #endif
 828             return false;
 829           }
 830         } else {
 831           assert(mem->is_Store() || mem->is_LoadStore(), "unexpected node type: %s", mem->Name());
 832 #ifndef PRODUCT
 833           if (PrintOptimizeStringConcat) {
 834             tty->print("fusion has incorrect memory flow (unexpected source) for ");
 835             _begin->jvms()->dump_spec(tty); tty->cr();
 836             path.dump();
 837           }
 838 #endif
 839           return false;
 840         }
 841       } else {
 842         // For memory that feeds into constructors it's more complicated.
 843         // However the advantage is that any side effect that happens between the Allocate/Initialize and
 844         // the constructor will have to be control-dependent on Initialize.
 845         // So we actually don't have to do anything, since it's going to be caught by the control flow
 846         // analysis.
 847 #ifdef ASSERT
 848         // Do a quick verification of the control pattern between the constructor and the initialize node
 849         assert(curr->is_Call(), "constructor should be a call");
 850         // Go up the control starting from the constructor call
 851         Node* ctrl = curr->in(0);
 852         IfNode* iff = NULL;
 853         RegionNode* copy = NULL;
 854 
 855         while (true) {
 856           // skip known check patterns
 857           if (ctrl->is_Region()) {
 858             if (ctrl->as_Region()->is_copy()) {
 859               copy = ctrl->as_Region();
 860               ctrl = copy->is_copy();
 861             } else { // a cast
 862               assert(ctrl->req() == 3 &&
 863                      ctrl->in(1) != NULL && ctrl->in(1)->is_Proj() &&
 864                      ctrl->in(2) != NULL && ctrl->in(2)->is_Proj() &&
 865                      ctrl->in(1)->in(0) == ctrl->in(2)->in(0) &&
 866                      ctrl->in(1)->in(0) != NULL && ctrl->in(1)->in(0)->is_If(),
 867                      "must be a simple diamond");
 868               Node* true_proj = ctrl->in(1)->is_IfTrue() ? ctrl->in(1) : ctrl->in(2);
 869               for (SimpleDUIterator i(true_proj); i.has_next(); i.next()) {
 870                 Node* use = i.get();
 871                 assert(use == ctrl || use->is_ConstraintCast(),
 872                        "unexpected user: %s", use->Name());
 873               }
 874 
 875               iff = ctrl->in(1)->in(0)->as_If();
 876               ctrl = iff->in(0);
 877             }
 878           } else if (ctrl->is_IfTrue()) { // null checks, class checks
 879             iff = ctrl->in(0)->as_If();
 880             // Verify that the other arm is an uncommon trap
 881             Node* otherproj = iff->proj_out(1 - ctrl->as_Proj()->_con);
 882             CallStaticJavaNode* call = otherproj->unique_out()->isa_CallStaticJava();
 883             assert(strcmp(call->_name, "uncommon_trap") == 0, "must be uncommon trap");
 884             ctrl = iff->in(0);
 885           } else {
 886             break;
 887           }
 888         }
 889 
 890         assert(ctrl->is_Proj(), "must be a projection");
 891         assert(ctrl->in(0)->is_Initialize(), "should be initialize");
 892         for (SimpleDUIterator i(ctrl); i.has_next(); i.next()) {
 893           Node* use = i.get();
 894           assert(use == copy || use == iff || use == curr || use->is_CheckCastPP() || use->is_Load(),
 895                  "unexpected user: %s", use->Name());
 896         }
 897 #endif // ASSERT
 898       }
 899     }
 900   }
 901 
 902 #ifndef PRODUCT
 903   if (PrintOptimizeStringConcat) {
 904     tty->print("fusion has correct memory flow for ");
 905     _begin->jvms()->dump_spec(tty); tty->cr();
 906     tty->cr();
 907   }
 908 #endif
 909   return true;
 910 }
 911 
 912 bool StringConcat::validate_control_flow() {
 913   // We found all the calls and arguments now lets see if it's
 914   // safe to transform the graph as we would expect.
 915 
 916   // Check to see if this resulted in too many uncommon traps previously
 917   if (Compile::current()->too_many_traps(_begin->jvms()->method(), _begin->jvms()->bci(),
 918                         Deoptimization::Reason_intrinsic)) {
 919     return false;
 920   }
 921 
 922   // Walk backwards over the control flow from toString to the
 923   // allocation and make sure all the control flow is ok.  This
 924   // means it's either going to be eliminated once the calls are
 925   // removed or it can safely be transformed into an uncommon
 926   // trap.
 927 
 928   int null_check_count = 0;
 929   Unique_Node_List ctrl_path;
 930 
 931   assert(_control.contains(_begin), "missing");
 932   assert(_control.contains(_end), "missing");
 933 
 934   // Collect the nodes that we know about and will eliminate into ctrl_path
 935   for (uint i = 0; i < _control.size(); i++) {
 936     // Push the call and it's control projection
 937     Node* n = _control.at(i);
 938     if (n->is_Allocate()) {
 939       AllocateNode* an = n->as_Allocate();
 940       InitializeNode* init = an->initialization();
 941       ctrl_path.push(init);
 942       ctrl_path.push(init->as_Multi()->proj_out(0));
 943     }
 944     if (n->is_Call()) {
 945       CallNode* cn = n->as_Call();
 946       ctrl_path.push(cn);
 947       ctrl_path.push(cn->proj_out(0));
 948       ctrl_path.push(cn->proj_out(0)->unique_out());
 949       Node* catchproj = cn->proj_out(0)->unique_out()->as_Catch()->proj_out_or_null(0);
 950       if (catchproj != NULL) {
 951         ctrl_path.push(catchproj);
 952       }
 953     } else {
 954       ShouldNotReachHere();
 955     }
 956   }
 957 
 958   // Skip backwards through the control checking for unexpected control flow
 959   Node* ptr = _end;
 960   bool fail = false;
 961   while (ptr != _begin) {
 962     if (ptr->is_Call() && ctrl_path.member(ptr)) {
 963       ptr = ptr->in(0);
 964     } else if (ptr->is_CatchProj() && ctrl_path.member(ptr)) {
 965       ptr = ptr->in(0)->in(0)->in(0);
 966       assert(ctrl_path.member(ptr), "should be a known piece of control");
 967     } else if (ptr->is_IfTrue()) {
 968       IfNode* iff = ptr->in(0)->as_If();
 969       BoolNode* b = iff->in(1)->isa_Bool();
 970 
 971       if (b == NULL) {
 972 #ifndef PRODUCT
 973         if (PrintOptimizeStringConcat) {
 974           tty->print_cr("unexpected input to IfNode");
 975           iff->in(1)->dump();
 976           tty->cr();
 977         }
 978 #endif
 979         fail = true;
 980         break;
 981       }
 982 
 983       Node* cmp = b->in(1);
 984       Node* v1 = cmp->in(1);
 985       Node* v2 = cmp->in(2);
 986       Node* otherproj = iff->proj_out(1 - ptr->as_Proj()->_con);
 987 
 988       // Null check of the return of append which can simply be eliminated
 989       if (b->_test._test == BoolTest::ne &&
 990           v2->bottom_type() == TypePtr::NULL_PTR &&
 991           v1->is_Proj() && ctrl_path.member(v1->in(0))) {
 992         // NULL check of the return value of the append
 993         null_check_count++;
 994         if (otherproj->outcnt() == 1) {
 995           CallStaticJavaNode* call = otherproj->unique_out()->isa_CallStaticJava();
 996           if (call != NULL && call->_name != NULL && strcmp(call->_name, "uncommon_trap") == 0) {
 997             ctrl_path.push(call);
 998           }
 999         }
1000         _control.push(ptr);
1001         ptr = ptr->in(0)->in(0);
1002         continue;
1003       }
1004 
1005       // A test which leads to an uncommon trap which should be safe.
1006       // Later this trap will be converted into a trap that restarts
1007       // at the beginning.
1008       if (otherproj->outcnt() == 1) {
1009         CallStaticJavaNode* call = otherproj->unique_out()->isa_CallStaticJava();
1010         if (call != NULL && call->_name != NULL && strcmp(call->_name, "uncommon_trap") == 0) {
1011           // control flow leads to uct so should be ok
1012           _uncommon_traps.push(call);
1013           ctrl_path.push(call);
1014           ptr = ptr->in(0)->in(0);
1015           continue;
1016         }
1017       }
1018 
1019 #ifndef PRODUCT
1020       // Some unexpected control flow we don't know how to handle.
1021       if (PrintOptimizeStringConcat) {
1022         tty->print_cr("failing with unknown test");
1023         b->dump();
1024         cmp->dump();
1025         v1->dump();
1026         v2->dump();
1027         tty->cr();
1028       }
1029 #endif
1030       fail = true;
1031       break;
1032     } else if (ptr->is_Proj() && ptr->in(0)->is_Initialize()) {
1033       ptr = ptr->in(0)->in(0);
1034     } else if (ptr->is_Region()) {
1035       Node* copy = ptr->as_Region()->is_copy();
1036       if (copy != NULL) {
1037         ptr = copy;
1038         continue;
1039       }
1040       if (ptr->req() == 3 &&
1041           ptr->in(1) != NULL && ptr->in(1)->is_Proj() &&
1042           ptr->in(2) != NULL && ptr->in(2)->is_Proj() &&
1043           ptr->in(1)->in(0) == ptr->in(2)->in(0) &&
1044           ptr->in(1)->in(0) != NULL && ptr->in(1)->in(0)->is_If()) {
1045         // Simple diamond.
1046         // XXX should check for possibly merging stores.  simple data merges are ok.
1047         // The IGVN will make this simple diamond go away when it
1048         // transforms the Region. Make sure it sees it.
1049         Compile::current()->record_for_igvn(ptr);
1050         _control.push(ptr);
1051         ptr = ptr->in(1)->in(0)->in(0);
1052         continue;
1053       }
1054 #ifndef PRODUCT
1055       if (PrintOptimizeStringConcat) {
1056         tty->print_cr("fusion would fail for region");
1057         _begin->dump();
1058         ptr->dump(2);
1059       }
1060 #endif
1061       fail = true;
1062       break;
1063     } else {
1064       // other unknown control
1065       if (!fail) {
1066 #ifndef PRODUCT
1067         if (PrintOptimizeStringConcat) {
1068           tty->print_cr("fusion would fail for");
1069           _begin->dump();
1070         }
1071 #endif
1072         fail = true;
1073       }
1074 #ifndef PRODUCT
1075       if (PrintOptimizeStringConcat) {
1076         ptr->dump();
1077       }
1078 #endif
1079       ptr = ptr->in(0);
1080     }
1081   }
1082 #ifndef PRODUCT
1083   if (PrintOptimizeStringConcat && fail) {
1084     tty->cr();
1085   }
1086 #endif
1087   if (fail) return !fail;
1088 
1089   // Validate that all these results produced are contained within
1090   // this cluster of objects.  First collect all the results produced
1091   // by calls in the region.
1092   _stringopts->_visited.clear();
1093   Node_List worklist;
1094   Node* final_result = _end->proj_out_or_null(TypeFunc::Parms);
1095   for (uint i = 0; i < _control.size(); i++) {
1096     CallNode* cnode = _control.at(i)->isa_Call();
1097     if (cnode != NULL) {
1098       _stringopts->_visited.test_set(cnode->_idx);
1099     }
1100     Node* result = cnode != NULL ? cnode->proj_out_or_null(TypeFunc::Parms) : NULL;
1101     if (result != NULL && result != final_result) {
1102       worklist.push(result);
1103     }
1104   }
1105 
1106   Node* last_result = NULL;
1107   while (worklist.size() > 0) {
1108     Node* result = worklist.pop();
1109     if (_stringopts->_visited.test_set(result->_idx))
1110       continue;
1111     for (SimpleDUIterator i(result); i.has_next(); i.next()) {
1112       Node *use = i.get();
1113       if (ctrl_path.member(use)) {
1114         // already checked this
1115         continue;
1116       }
1117       int opc = use->Opcode();
1118       if (opc == Op_CmpP || opc == Op_Node) {
1119         ctrl_path.push(use);
1120         continue;
1121       }
1122       if (opc == Op_CastPP || opc == Op_CheckCastPP) {
1123         for (SimpleDUIterator j(use); j.has_next(); j.next()) {
1124           worklist.push(j.get());
1125         }
1126         worklist.push(use->in(1));
1127         ctrl_path.push(use);
1128         continue;
1129       }
1130 #ifndef PRODUCT
1131       if (PrintOptimizeStringConcat) {
1132         if (result != last_result) {
1133           last_result = result;
1134           tty->print_cr("extra uses for result:");
1135           last_result->dump();
1136         }
1137         use->dump();
1138       }
1139 #endif
1140       fail = true;
1141       break;
1142     }
1143   }
1144 
1145 #ifndef PRODUCT
1146   if (PrintOptimizeStringConcat && !fail) {
1147     ttyLocker ttyl;
1148     tty->cr();
1149     tty->print("fusion has correct control flow (%d %d) for ", null_check_count, _uncommon_traps.size());
1150     _begin->jvms()->dump_spec(tty); tty->cr();
1151     for (int i = 0; i < num_arguments(); i++) {
1152       argument(i)->dump();
1153     }
1154     _control.dump();
1155     tty->cr();
1156   }
1157 #endif
1158 
1159   return !fail;
1160 }
1161 
1162 Node* PhaseStringOpts::fetch_static_field(GraphKit& kit, ciField* field) {
1163   const TypeInstPtr* mirror_type = TypeInstPtr::make(field->holder()->java_mirror());
1164   Node* klass_node = __ makecon(mirror_type);
1165   BasicType bt = field->layout_type();
1166   ciType* field_klass = field->type();
1167 
1168   const Type *type;
1169   if( bt == T_OBJECT ) {
1170     if (!field->type()->is_loaded()) {
1171       type = TypeInstPtr::BOTTOM;
1172     } else if (field->is_static_constant()) {
1173       // This can happen if the constant oop is non-perm.
1174       ciObject* con = field->constant_value().as_object();
1175       // Do not "join" in the previous type; it doesn't add value,
1176       // and may yield a vacuous result if the field is of interface type.
1177       type = TypeOopPtr::make_from_constant(con, true)->isa_oopptr();
1178       assert(type != NULL, "field singleton type must be consistent");
1179       return __ makecon(type);
1180     } else {
1181       type = TypeOopPtr::make_from_klass(field_klass->as_klass());
1182     }
1183   } else {
1184     type = Type::get_const_basic_type(bt);
1185   }
1186 
1187   return kit.make_load(NULL, kit.basic_plus_adr(klass_node, field->offset_in_bytes()),
1188                        type, T_OBJECT,
1189                        C->get_alias_index(mirror_type->add_offset(field->offset_in_bytes())),
1190                        MemNode::unordered);
1191 }
1192 
1193 Node* PhaseStringOpts::int_stringSize(GraphKit& kit, Node* arg) {
1194   if (arg->is_Con()) {
1195     // Constant integer. Compute constant length using Integer.sizeTable
1196     int arg_val = arg->get_int();
1197     int count = 1;
1198     if (arg_val < 0) {
1199       // Special case for min_jint - it can't be negated.
1200       if (arg_val == min_jint) {
1201         return __ intcon(11);
1202       }
1203 
1204       arg_val = -arg_val;
1205       count++;
1206     }
1207 
1208     ciArray* size_table = (ciArray*)size_table_field->constant_value().as_object();
1209     for (int i = 0; i < size_table->length(); i++) {
1210       if (arg_val <= size_table->element_value(i).as_int()) {
1211         count += i;
1212         break;
1213       }
1214     }
1215     return __ intcon(count);
1216   }
1217 
1218   RegionNode *final_merge = new RegionNode(3);
1219   kit.gvn().set_type(final_merge, Type::CONTROL);
1220   Node* final_size = new PhiNode(final_merge, TypeInt::INT);
1221   kit.gvn().set_type(final_size, TypeInt::INT);
1222 
1223   IfNode* iff = kit.create_and_map_if(kit.control(),
1224                                       __ Bool(__ CmpI(arg, __ intcon(0x80000000)), BoolTest::ne),
1225                                       PROB_FAIR, COUNT_UNKNOWN);
1226   Node* is_min = __ IfFalse(iff);
1227   final_merge->init_req(1, is_min);
1228   final_size->init_req(1, __ intcon(11));
1229 
1230   kit.set_control(__ IfTrue(iff));
1231   if (kit.stopped()) {
1232     final_merge->init_req(2, C->top());
1233     final_size->init_req(2, C->top());
1234   } else {
1235 
1236     // int size = (i < 0) ? stringSize(-i) + 1 : stringSize(i);
1237     RegionNode *r = new RegionNode(3);
1238     kit.gvn().set_type(r, Type::CONTROL);
1239     Node *phi = new PhiNode(r, TypeInt::INT);
1240     kit.gvn().set_type(phi, TypeInt::INT);
1241     Node *size = new PhiNode(r, TypeInt::INT);
1242     kit.gvn().set_type(size, TypeInt::INT);
1243     Node* chk = __ CmpI(arg, __ intcon(0));
1244     Node* p = __ Bool(chk, BoolTest::lt);
1245     IfNode* iff = kit.create_and_map_if(kit.control(), p, PROB_FAIR, COUNT_UNKNOWN);
1246     Node* lessthan = __ IfTrue(iff);
1247     Node* greaterequal = __ IfFalse(iff);
1248     r->init_req(1, lessthan);
1249     phi->init_req(1, __ SubI(__ intcon(0), arg));
1250     size->init_req(1, __ intcon(1));
1251     r->init_req(2, greaterequal);
1252     phi->init_req(2, arg);
1253     size->init_req(2, __ intcon(0));
1254     kit.set_control(r);
1255     C->record_for_igvn(r);
1256     C->record_for_igvn(phi);
1257     C->record_for_igvn(size);
1258 
1259     // for (int i=0; ; i++)
1260     //   if (x <= sizeTable[i])
1261     //     return i+1;
1262 
1263     // Add loop predicate first.
1264     kit.add_empty_predicates();
1265     C->set_has_loops(true);
1266 
1267     RegionNode *loop = new RegionNode(3);
1268     loop->init_req(1, kit.control());
1269     kit.gvn().set_type(loop, Type::CONTROL);
1270 
1271     Node *index = new PhiNode(loop, TypeInt::INT);
1272     index->init_req(1, __ intcon(0));
1273     kit.gvn().set_type(index, TypeInt::INT);
1274     kit.set_control(loop);
1275     Node* sizeTable = fetch_static_field(kit, size_table_field);
1276 
1277     Node* value = kit.load_array_element(sizeTable, index, TypeAryPtr::INTS, /* set_ctrl */ false);
1278     C->record_for_igvn(value);
1279     Node* limit = __ CmpI(phi, value);
1280     Node* limitb = __ Bool(limit, BoolTest::le);
1281     IfNode* iff2 = kit.create_and_map_if(kit.control(), limitb, PROB_MIN, COUNT_UNKNOWN);
1282     Node* lessEqual = __ IfTrue(iff2);
1283     Node* greater = __ IfFalse(iff2);
1284 
1285     loop->init_req(2, greater);
1286     index->init_req(2, __ AddI(index, __ intcon(1)));
1287 
1288     kit.set_control(lessEqual);
1289     C->record_for_igvn(loop);
1290     C->record_for_igvn(index);
1291 
1292     final_merge->init_req(2, kit.control());
1293     final_size->init_req(2, __ AddI(__ AddI(index, size), __ intcon(1)));
1294   }
1295 
1296   kit.set_control(final_merge);
1297   C->record_for_igvn(final_merge);
1298   C->record_for_igvn(final_size);
1299 
1300   return final_size;
1301 }
1302 
1303 // Simplified version of Integer.getChars
1304 void PhaseStringOpts::getChars(GraphKit& kit, Node* arg, Node* dst_array, BasicType bt, Node* end, Node* final_merge, Node* final_mem, int merge_index) {
1305   // if (i < 0) {
1306   //     sign = '-';
1307   //     i = -i;
1308   // }
1309   IfNode* iff = kit.create_and_map_if(kit.control(), __ Bool(__ CmpI(arg, __ intcon(0)), BoolTest::lt),
1310                                       PROB_FAIR, COUNT_UNKNOWN);
1311 
1312   RegionNode* merge = new RegionNode(3);
1313   kit.gvn().set_type(merge, Type::CONTROL);
1314   Node* i = new PhiNode(merge, TypeInt::INT);
1315   kit.gvn().set_type(i, TypeInt::INT);
1316   Node* sign = new PhiNode(merge, TypeInt::INT);
1317   kit.gvn().set_type(sign, TypeInt::INT);
1318 
1319   merge->init_req(1, __ IfTrue(iff));
1320   i->init_req(1, __ SubI(__ intcon(0), arg));
1321   sign->init_req(1, __ intcon('-'));
1322   merge->init_req(2, __ IfFalse(iff));
1323   i->init_req(2, arg);
1324   sign->init_req(2, __ intcon(0));
1325 
1326   kit.set_control(merge);
1327 
1328   C->record_for_igvn(merge);
1329   C->record_for_igvn(i);
1330   C->record_for_igvn(sign);
1331 
1332   // for (;;) {
1333   //     q = i / 10;
1334   //     r = i - ((q << 3) + (q << 1));  // r = i-(q*10) ...
1335   //     buf [--charPos] = digits [r];
1336   //     i = q;
1337   //     if (i == 0) break;
1338   // }
1339 
1340   // Add loop predicate first.
1341   kit.add_empty_predicates();
1342 
1343   C->set_has_loops(true);
1344   RegionNode* head = new RegionNode(3);
1345   head->init_req(1, kit.control());
1346 
1347   kit.gvn().set_type(head, Type::CONTROL);
1348   Node* i_phi = new PhiNode(head, TypeInt::INT);
1349   i_phi->init_req(1, i);
1350   kit.gvn().set_type(i_phi, TypeInt::INT);
1351   Node* charPos = new PhiNode(head, TypeInt::INT);
1352   charPos->init_req(1, end);
1353   kit.gvn().set_type(charPos, TypeInt::INT);
1354   Node* mem = PhiNode::make(head, kit.memory(byte_adr_idx), Type::MEMORY, TypeAryPtr::BYTES);
1355   kit.gvn().set_type(mem, Type::MEMORY);
1356 
1357   kit.set_control(head);
1358   kit.set_memory(mem, byte_adr_idx);
1359 
1360   Node* q = __ DivI(kit.null(), i_phi, __ intcon(10));
1361   Node* r = __ SubI(i_phi, __ AddI(__ LShiftI(q, __ intcon(3)),
1362                                    __ LShiftI(q, __ intcon(1))));
1363   Node* index = __ SubI(charPos, __ intcon((bt == T_BYTE) ? 1 : 2));
1364   Node* ch = __ AddI(r, __ intcon('0'));
1365   Node* st = __ store_to_memory(kit.control(), kit.array_element_address(dst_array, index, T_BYTE),
1366                                 ch, bt, byte_adr_idx, MemNode::unordered, false /* require_atomic_access */,
1367                                 false /* unaligned */, (bt != T_BYTE) /* mismatched */);
1368 
1369   iff = kit.create_and_map_if(head, __ Bool(__ CmpI(q, __ intcon(0)), BoolTest::ne),
1370                               PROB_FAIR, COUNT_UNKNOWN);
1371   Node* ne = __ IfTrue(iff);
1372   Node* eq = __ IfFalse(iff);
1373 
1374   head->init_req(2, ne);
1375   mem->init_req(2, st);
1376 
1377   i_phi->init_req(2, q);
1378   charPos->init_req(2, index);
1379   charPos = index;
1380 
1381   kit.set_control(eq);
1382   kit.set_memory(st, byte_adr_idx);
1383 
1384   C->record_for_igvn(head);
1385   C->record_for_igvn(mem);
1386   C->record_for_igvn(i_phi);
1387   C->record_for_igvn(charPos);
1388 
1389   // if (sign != 0) {
1390   //     buf [--charPos] = sign;
1391   // }
1392   iff = kit.create_and_map_if(kit.control(), __ Bool(__ CmpI(sign, __ intcon(0)), BoolTest::ne),
1393                               PROB_FAIR, COUNT_UNKNOWN);
1394 
1395   final_merge->init_req(merge_index + 2, __ IfFalse(iff));
1396   final_mem->init_req(merge_index + 2, kit.memory(byte_adr_idx));
1397 
1398   kit.set_control(__ IfTrue(iff));
1399   if (kit.stopped()) {
1400     final_merge->init_req(merge_index + 1, C->top());
1401     final_mem->init_req(merge_index + 1, C->top());
1402   } else {
1403     Node* index = __ SubI(charPos, __ intcon((bt == T_BYTE) ? 1 : 2));
1404     st = __ store_to_memory(kit.control(), kit.array_element_address(dst_array, index, T_BYTE),
1405                             sign, bt, byte_adr_idx, MemNode::unordered, false /* require_atomic_access */,
1406                             false /* unaligned */, (bt != T_BYTE) /* mismatched */);
1407 
1408     final_merge->init_req(merge_index + 1, kit.control());
1409     final_mem->init_req(merge_index + 1, st);
1410   }
1411 }
1412 
1413 // Copy the characters representing arg into dst_array starting at start
1414 Node* PhaseStringOpts::int_getChars(GraphKit& kit, Node* arg, Node* dst_array, Node* dst_coder, Node* start, Node* size) {
1415   bool dcon = dst_coder->is_Con();
1416   bool dbyte = dcon ? (dst_coder->get_int() == java_lang_String::CODER_LATIN1) : false;
1417   Node* end = __ AddI(start, __ LShiftI(size, dst_coder));
1418 
1419   // The final_merge node has 4 entries in case the encoding is known:
1420   // (0) Control, (1) result w/ sign, (2) result w/o sign, (3) result for Integer.min_value
1421   // or 6 entries in case the encoding is not known:
1422   // (0) Control, (1) Latin1 w/ sign, (2) Latin1 w/o sign, (3) min_value, (4) UTF16 w/ sign, (5) UTF16 w/o sign
1423   RegionNode* final_merge = new RegionNode(dcon ? 4 : 6);
1424   kit.gvn().set_type(final_merge, Type::CONTROL);
1425 
1426   Node* final_mem = PhiNode::make(final_merge, kit.memory(byte_adr_idx), Type::MEMORY, TypeAryPtr::BYTES);
1427   kit.gvn().set_type(final_mem, Type::MEMORY);
1428 
1429   // need to handle arg == Integer.MIN_VALUE specially because negating doesn't make it positive
1430   IfNode* iff = kit.create_and_map_if(kit.control(), __ Bool(__ CmpI(arg, __ intcon(0x80000000)), BoolTest::ne),
1431                                       PROB_FAIR, COUNT_UNKNOWN);
1432 
1433   Node* old_mem = kit.memory(byte_adr_idx);
1434 
1435   kit.set_control(__ IfFalse(iff));
1436   if (kit.stopped()) {
1437     // Statically not equal to MIN_VALUE so this path is dead
1438     final_merge->init_req(3, kit.control());
1439   } else {
1440     copy_string(kit, __ makecon(TypeInstPtr::make(C->env()->the_min_jint_string())),
1441                 dst_array, dst_coder, start);
1442     final_merge->init_req(3, kit.control());
1443     final_mem->init_req(3, kit.memory(byte_adr_idx));
1444   }
1445 
1446   kit.set_control(__ IfTrue(iff));
1447   kit.set_memory(old_mem, byte_adr_idx);
1448 
1449   if (!dcon) {
1450     // Check encoding of destination
1451     iff = kit.create_and_map_if(kit.control(), __ Bool(__ CmpI(dst_coder, __ intcon(0)), BoolTest::eq),
1452                                 PROB_FAIR, COUNT_UNKNOWN);
1453     old_mem = kit.memory(byte_adr_idx);
1454   }
1455   if (!dcon || dbyte) {
1456     // Destination is Latin1,
1457     if (!dcon) {
1458       kit.set_control(__ IfTrue(iff));
1459     }
1460     getChars(kit, arg, dst_array, T_BYTE, end, final_merge, final_mem);
1461   }
1462   if (!dcon || !dbyte) {
1463     // Destination is UTF16
1464     int merge_index = 0;
1465     if (!dcon) {
1466       kit.set_control(__ IfFalse(iff));
1467       kit.set_memory(old_mem, byte_adr_idx);
1468       merge_index = 3; // Account for Latin1 case
1469     }
1470     getChars(kit, arg, dst_array, T_CHAR, end, final_merge, final_mem, merge_index);
1471   }
1472 
1473   // Final merge point for Latin1 and UTF16 case
1474   kit.set_control(final_merge);
1475   kit.set_memory(final_mem, byte_adr_idx);
1476 
1477   C->record_for_igvn(final_merge);
1478   C->record_for_igvn(final_mem);
1479   return end;
1480 }
1481 
1482 // Copy 'count' bytes/chars from src_array to dst_array starting at index start
1483 void PhaseStringOpts::arraycopy(GraphKit& kit, IdealKit& ideal, Node* src_array, Node* dst_array, BasicType elembt, Node* start, Node* count) {
1484   assert(elembt == T_BYTE || elembt == T_CHAR, "Invalid type for arraycopy");
1485 
1486   if (elembt == T_CHAR) {
1487     // Get number of chars
1488     count = __ RShiftI(count, __ intcon(1));
1489   }
1490 
1491   Node* extra = NULL;
1492 #ifdef _LP64
1493   count = __ ConvI2L(count);
1494   extra = C->top();
1495 #endif
1496 
1497   Node* src_ptr = __ array_element_address(src_array, __ intcon(0), T_BYTE);
1498   Node* dst_ptr = __ array_element_address(dst_array, start, T_BYTE);
1499   // Check if destination address is aligned to HeapWordSize
1500   const TypeInt* tdst = __ gvn().type(start)->is_int();
1501   bool aligned = tdst->is_con() && ((tdst->get_con() * type2aelembytes(T_BYTE)) % HeapWordSize == 0);
1502   // Figure out which arraycopy runtime method to call (disjoint, uninitialized).
1503   const char* copyfunc_name = "arraycopy";
1504   address     copyfunc_addr = StubRoutines::select_arraycopy_function(elembt, aligned, true, copyfunc_name, true);
1505   ideal.make_leaf_call_no_fp(OptoRuntime::fast_arraycopy_Type(), copyfunc_addr, copyfunc_name,
1506                              TypeAryPtr::BYTES, src_ptr, dst_ptr, count, extra);
1507 }
1508 
1509 #undef __
1510 #define __ ideal.
1511 
1512 // Copy contents of a Latin1 encoded string from src_array to dst_array
1513 void PhaseStringOpts::copy_latin1_string(GraphKit& kit, IdealKit& ideal, Node* src_array, IdealVariable& count,
1514                                          Node* dst_array, Node* dst_coder, Node* start) {
1515   bool dcon = dst_coder->is_Con();
1516   bool dbyte = dcon ? (dst_coder->get_int() == java_lang_String::CODER_LATIN1) : false;
1517 
1518   if (!dcon) {
1519     __ if_then(dst_coder, BoolTest::eq, __ ConI(java_lang_String::CODER_LATIN1));
1520   }
1521   if (!dcon || dbyte) {
1522     // Destination is Latin1. Simply emit a byte arraycopy.
1523     arraycopy(kit, ideal, src_array, dst_array, T_BYTE, start, __ value(count));
1524   }
1525   if (!dcon) {
1526     __ else_();
1527   }
1528   if (!dcon || !dbyte) {
1529     // Destination is UTF16. Inflate src_array into dst_array.
1530     kit.sync_kit(ideal);
1531     if (Matcher::match_rule_supported(Op_StrInflatedCopy)) {
1532       // Use fast intrinsic
1533       Node* src = kit.array_element_address(src_array, kit.intcon(0), T_BYTE);
1534       Node* dst = kit.array_element_address(dst_array, start, T_BYTE);
1535       kit.inflate_string(src, dst, TypeAryPtr::BYTES, __ value(count));
1536     } else {
1537       // No intrinsic available, use slow method
1538       kit.inflate_string_slow(src_array, dst_array, start, __ value(count));
1539     }
1540     ideal.sync_kit(&kit);
1541     // Multiply count by two since we now need two bytes per char
1542     __ set(count, __ LShiftI(__ value(count), __ ConI(1)));
1543   }
1544   if (!dcon) {
1545     __ end_if();
1546   }
1547 }
1548 
1549 // Read two bytes from index and index+1 and convert them to a char
1550 static jchar readChar(ciTypeArray* array, int index) {
1551   int shift_high, shift_low;
1552 #ifdef VM_LITTLE_ENDIAN
1553     shift_high = 0;
1554     shift_low = 8;
1555 #else
1556     shift_high = 8;
1557     shift_low = 0;
1558 #endif
1559 
1560   jchar b1 = ((jchar) array->byte_at(index)) & 0xff;
1561   jchar b2 = ((jchar) array->byte_at(index+1)) & 0xff;
1562   return (b1 << shift_high) | (b2 << shift_low);
1563 }
1564 
1565 // Copy contents of constant src_array to dst_array by emitting individual stores
1566 void PhaseStringOpts::copy_constant_string(GraphKit& kit, IdealKit& ideal, ciTypeArray* src_array, IdealVariable& count,
1567                                            bool src_is_byte, Node* dst_array, Node* dst_coder, Node* start) {
1568   bool dcon = dst_coder->is_Con();
1569   bool dbyte = dcon ? (dst_coder->get_int() == java_lang_String::CODER_LATIN1) : false;
1570   int length = src_array->length();
1571 
1572   if (!dcon) {
1573     __ if_then(dst_coder, BoolTest::eq, __ ConI(java_lang_String::CODER_LATIN1));
1574   }
1575   if (!dcon || dbyte) {
1576     // Destination is Latin1. Copy each byte of src_array into dst_array.
1577     Node* index = start;
1578     for (int i = 0; i < length; i++) {
1579       Node* adr = kit.array_element_address(dst_array, index, T_BYTE);
1580       Node* val = __ ConI(src_array->byte_at(i));
1581       __ store(__ ctrl(), adr, val, T_BYTE, byte_adr_idx, MemNode::unordered);
1582       index = __ AddI(index, __ ConI(1));
1583     }
1584   }
1585   if (!dcon) {
1586     __ else_();
1587   }
1588   if (!dcon || !dbyte) {
1589     // Destination is UTF16. Copy each char of src_array into dst_array.
1590     Node* index = start;
1591     for (int i = 0; i < length; i++) {
1592       Node* adr = kit.array_element_address(dst_array, index, T_BYTE);
1593       jchar val;
1594       if (src_is_byte) {
1595         val = src_array->byte_at(i) & 0xff;
1596       } else {
1597         val = readChar(src_array, i++);
1598       }
1599       __ store(__ ctrl(), adr, __ ConI(val), T_CHAR, byte_adr_idx, MemNode::unordered, false /* require_atomic_access */,
1600                true /* mismatched */);
1601       index = __ AddI(index, __ ConI(2));
1602     }
1603     if (src_is_byte) {
1604       // Multiply count by two since we now need two bytes per char
1605       __ set(count, __ ConI(2 * length));
1606     }
1607   }
1608   if (!dcon) {
1609     __ end_if();
1610   }
1611 }
1612 
1613 // Compress copy contents of the byte/char String str into dst_array starting at index start.
1614 Node* PhaseStringOpts::copy_string(GraphKit& kit, Node* str, Node* dst_array, Node* dst_coder, Node* start) {
1615   Node* src_array = kit.load_String_value(str, true);
1616 
1617   IdealKit ideal(&kit, true, true);
1618   IdealVariable count(ideal); __ declarations_done();
1619 
1620   if (str->is_Con()) {
1621     // Constant source string
1622     ciTypeArray* src_array_type = get_constant_value(kit, str);
1623 
1624     // Check encoding of constant string
1625     bool src_is_byte = (get_constant_coder(kit, str) == java_lang_String::CODER_LATIN1);
1626 
1627     // For small constant strings just emit individual stores.
1628     // A length of 6 seems like a good space/speed tradeof.
1629     __ set(count, __ ConI(src_array_type->length()));
1630     int src_len = src_array_type->length() / (src_is_byte ? 1 : 2);
1631     if (src_len < unroll_string_copy_length) {
1632       // Small constant string
1633       copy_constant_string(kit, ideal, src_array_type, count, src_is_byte, dst_array, dst_coder, start);
1634     } else if (src_is_byte) {
1635       // Source is Latin1
1636       copy_latin1_string(kit, ideal, src_array, count, dst_array, dst_coder, start);
1637     } else {
1638       // Source is UTF16 (destination too). Simply emit a char arraycopy.
1639       arraycopy(kit, ideal, src_array, dst_array, T_CHAR, start, __ value(count));
1640     }
1641   } else {
1642     Node* size = kit.load_array_length(src_array);
1643     __ set(count, size);
1644     // Non-constant source string
1645     if (CompactStrings) {
1646       // Emit runtime check for coder
1647       Node* coder = kit.load_String_coder(str, true);
1648       __ if_then(coder, BoolTest::eq, __ ConI(java_lang_String::CODER_LATIN1)); {
1649         // Source is Latin1
1650         copy_latin1_string(kit, ideal, src_array, count, dst_array, dst_coder, start);
1651       } __ else_();
1652     }
1653     // Source is UTF16 (destination too). Simply emit a char arraycopy.
1654     arraycopy(kit, ideal, src_array, dst_array, T_CHAR, start, __ value(count));
1655 
1656     if (CompactStrings) {
1657       __ end_if();
1658     }
1659   }
1660 
1661   // Finally sync IdealKit and GraphKit.
1662   kit.sync_kit(ideal);
1663   return __ AddI(start, __ value(count));
1664 }
1665 
1666 // Compress copy the char into dst_array at index start.
1667 Node* PhaseStringOpts::copy_char(GraphKit& kit, Node* val, Node* dst_array, Node* dst_coder, Node* start) {
1668   bool dcon = (dst_coder != NULL) && dst_coder->is_Con();
1669   bool dbyte = dcon ? (dst_coder->get_int() == java_lang_String::CODER_LATIN1) : false;
1670 
1671   IdealKit ideal(&kit, true, true);
1672   IdealVariable end(ideal); __ declarations_done();
1673   Node* adr = kit.array_element_address(dst_array, start, T_BYTE);
1674   if (!dcon){
1675     __ if_then(dst_coder, BoolTest::eq, __ ConI(java_lang_String::CODER_LATIN1));
1676   }
1677   if (!dcon || dbyte) {
1678     // Destination is Latin1. Store a byte.
1679     __ store(__ ctrl(), adr, val, T_BYTE, byte_adr_idx, MemNode::unordered);
1680     __ set(end, __ AddI(start, __ ConI(1)));
1681   }
1682   if (!dcon) {
1683     __ else_();
1684   }
1685   if (!dcon || !dbyte) {
1686     // Destination is UTF16. Store a char.
1687     __ store(__ ctrl(), adr, val, T_CHAR, byte_adr_idx, MemNode::unordered, false /* require_atomic_access */,
1688              true /* mismatched */);
1689     __ set(end, __ AddI(start, __ ConI(2)));
1690   }
1691   if (!dcon) {
1692     __ end_if();
1693   }
1694   // Finally sync IdealKit and GraphKit.
1695   kit.sync_kit(ideal);
1696   return __ value(end);
1697 }
1698 
1699 #undef __
1700 #define __ kit.
1701 
1702 // Allocate a byte array of specified length.
1703 Node* PhaseStringOpts::allocate_byte_array(GraphKit& kit, IdealKit* ideal, Node* length) {
1704   if (ideal != NULL) {
1705     // Sync IdealKit and graphKit.
1706     kit.sync_kit(*ideal);
1707   }
1708   Node* byte_array = NULL;
1709   {
1710     PreserveReexecuteState preexecs(&kit);
1711     // The original jvms is for an allocation of either a String or
1712     // StringBuffer so no stack adjustment is necessary for proper
1713     // reexecution.  If we deoptimize in the slow path the bytecode
1714     // will be reexecuted and the char[] allocation will be thrown away.
1715     kit.jvms()->set_should_reexecute(true);
1716     byte_array = kit.new_array(__ makecon(TypeKlassPtr::make(ciTypeArrayKlass::make(T_BYTE))),
1717                                length, 1);
1718   }
1719 
1720   // Mark the allocation so that zeroing is skipped since the code
1721   // below will overwrite the entire array
1722   AllocateArrayNode* byte_alloc = AllocateArrayNode::Ideal_array_allocation(byte_array, _gvn);
1723   byte_alloc->maybe_set_complete(_gvn);
1724 
1725   if (ideal != NULL) {
1726     // Sync IdealKit and graphKit.
1727     ideal->sync_kit(&kit);
1728   }
1729   return byte_array;
1730 }
1731 
1732 jbyte PhaseStringOpts::get_constant_coder(GraphKit& kit, Node* str) {
1733   assert(str->is_Con(), "String must be constant");
1734   const TypeOopPtr* str_type = kit.gvn().type(str)->isa_oopptr();
1735   ciInstance* str_instance = str_type->const_oop()->as_instance();
1736   jbyte coder = str_instance->field_value_by_offset(java_lang_String::coder_offset()).as_byte();
1737   assert(CompactStrings || (coder == java_lang_String::CODER_UTF16), "Strings must be UTF16 encoded");
1738   return coder;
1739 }
1740 
1741 int PhaseStringOpts::get_constant_length(GraphKit& kit, Node* str) {
1742   assert(str->is_Con(), "String must be constant");
1743   return get_constant_value(kit, str)->length();
1744 }
1745 
1746 ciTypeArray* PhaseStringOpts::get_constant_value(GraphKit& kit, Node* str) {
1747   assert(str->is_Con(), "String must be constant");
1748   const TypeOopPtr* str_type = kit.gvn().type(str)->isa_oopptr();
1749   ciInstance* str_instance = str_type->const_oop()->as_instance();
1750   ciObject* src_array = str_instance->field_value_by_offset(java_lang_String::value_offset()).as_object();
1751   return src_array->as_type_array();
1752 }
1753 
1754 void PhaseStringOpts::replace_string_concat(StringConcat* sc) {
1755   // Log a little info about the transformation
1756   sc->maybe_log_transform();
1757 
1758   // pull the JVMState of the allocation into a SafePointNode to serve as
1759   // as a shim for the insertion of the new code.
1760   JVMState* jvms     = sc->begin()->jvms()->clone_shallow(C);
1761   uint size = sc->begin()->req();
1762   SafePointNode* map = new SafePointNode(size, jvms);
1763 
1764   // copy the control and memory state from the final call into our
1765   // new starting state.  This allows any preceeding tests to feed
1766   // into the new section of code.
1767   for (uint i1 = 0; i1 < TypeFunc::Parms; i1++) {
1768     map->init_req(i1, sc->end()->in(i1));
1769   }
1770   // blow away old allocation arguments
1771   for (uint i1 = TypeFunc::Parms; i1 < jvms->debug_start(); i1++) {
1772     map->init_req(i1, C->top());
1773   }
1774   // Copy the rest of the inputs for the JVMState
1775   for (uint i1 = jvms->debug_start(); i1 < sc->begin()->req(); i1++) {
1776     map->init_req(i1, sc->begin()->in(i1));
1777   }
1778   // Make sure the memory state is a MergeMem for parsing.
1779   if (!map->in(TypeFunc::Memory)->is_MergeMem()) {
1780     map->set_req(TypeFunc::Memory, MergeMemNode::make(map->in(TypeFunc::Memory)));
1781   }
1782 
1783   jvms->set_map(map);
1784   map->ensure_stack(jvms, jvms->method()->max_stack());
1785 
1786   // disconnect all the old StringBuilder calls from the graph
1787   sc->eliminate_unneeded_control();
1788 
1789   // At this point all the old work has been completely removed from
1790   // the graph and the saved JVMState exists at the point where the
1791   // final toString call used to be.
1792   GraphKit kit(jvms);
1793 
1794   // There may be uncommon traps which are still using the
1795   // intermediate states and these need to be rewritten to point at
1796   // the JVMState at the beginning of the transformation.
1797   sc->convert_uncommon_traps(kit, jvms);
1798 
1799   // Now insert the logic to compute the size of the string followed
1800   // by all the logic to construct array and resulting string.
1801 
1802   Node* null_string = __ makecon(TypeInstPtr::make(C->env()->the_null_string()));
1803 
1804   // Create a region for the overflow checks to merge into.
1805   int args = MAX2(sc->num_arguments(), 1);
1806   RegionNode* overflow = new RegionNode(args);
1807   kit.gvn().set_type(overflow, Type::CONTROL);
1808 
1809   // Create a hook node to hold onto the individual sizes since they
1810   // are need for the copying phase.
1811   Node* string_sizes = new Node(args);
1812 
1813   Node* coder = __ intcon(0);
1814   Node* length = __ intcon(0);
1815   // If at least one argument is UTF16 encoded, we can fix the encoding.
1816   bool coder_fixed = false;
1817 
1818   if (!CompactStrings) {
1819     // Fix encoding of result string to UTF16
1820     coder_fixed = true;
1821     coder = __ intcon(java_lang_String::CODER_UTF16);
1822   }
1823 
1824   for (int argi = 0; argi < sc->num_arguments(); argi++) {
1825     Node* arg = sc->argument(argi);
1826     switch (sc->mode(argi)) {
1827       case StringConcat::NegativeIntCheckMode: {
1828         // Initial capacity argument might be negative in which case StringBuilder(int) throws
1829         // a NegativeArraySizeException. Insert a runtime check with an uncommon trap.
1830         const TypeInt* type = kit.gvn().type(arg)->is_int();
1831         assert(type->_hi >= 0 && type->_lo < 0, "no runtime int check needed");
1832         Node* p = __ Bool(__ CmpI(arg, kit.intcon(0)), BoolTest::ge);
1833         IfNode* iff = kit.create_and_map_if(kit.control(), p, PROB_MIN, COUNT_UNKNOWN);
1834         {
1835           // Negative int -> uncommon trap.
1836           PreserveJVMState pjvms(&kit);
1837           kit.set_control(__ IfFalse(iff));
1838           kit.uncommon_trap(Deoptimization::Reason_intrinsic,
1839                             Deoptimization::Action_maybe_recompile);
1840         }
1841         kit.set_control(__ IfTrue(iff));
1842         break;
1843       }
1844       case StringConcat::IntMode: {
1845         Node* string_size = int_stringSize(kit, arg);
1846 
1847         // accumulate total
1848         length = __ AddI(length, string_size);
1849 
1850         // Cache this value for the use by int_toString
1851         string_sizes->init_req(argi, string_size);
1852         break;
1853       }
1854       case StringConcat::StringNullCheckMode: {
1855         const Type* type = kit.gvn().type(arg);
1856         assert(type != TypePtr::NULL_PTR, "missing check");
1857         if (!type->higher_equal(TypeInstPtr::NOTNULL)) {
1858           // Null check with uncommon trap since
1859           // StringBuilder(null) throws exception.
1860           // Use special uncommon trap instead of
1861           // calling normal do_null_check().
1862           Node* p = __ Bool(__ CmpP(arg, kit.null()), BoolTest::ne);
1863           IfNode* iff = kit.create_and_map_if(kit.control(), p, PROB_MIN, COUNT_UNKNOWN);
1864           overflow->add_req(__ IfFalse(iff));
1865           Node* notnull = __ IfTrue(iff);
1866           kit.set_control(notnull); // set control for the cast_not_null
1867           arg = kit.cast_not_null(arg, false);
1868           sc->set_argument(argi, arg);
1869         }
1870         assert(kit.gvn().type(arg)->higher_equal(TypeInstPtr::NOTNULL), "sanity");
1871         // Fallthrough to add string length.
1872       }
1873       case StringConcat::StringMode: {
1874         const Type* type = kit.gvn().type(arg);
1875         Node* count = NULL;
1876         Node* arg_coder = NULL;
1877         if (type == TypePtr::NULL_PTR) {
1878           // replace the argument with the null checked version
1879           arg = null_string;
1880           sc->set_argument(argi, arg);
1881           count = kit.load_String_length(arg, true);
1882           arg_coder = kit.load_String_coder(arg, true);
1883         } else if (!type->higher_equal(TypeInstPtr::NOTNULL)) {
1884           // s = s != null ? s : "null";
1885           // length = length + (s.count - s.offset);
1886           RegionNode *r = new RegionNode(3);
1887           kit.gvn().set_type(r, Type::CONTROL);
1888           Node *phi = new PhiNode(r, type);
1889           kit.gvn().set_type(phi, phi->bottom_type());
1890           Node* p = __ Bool(__ CmpP(arg, kit.null()), BoolTest::ne);
1891           IfNode* iff = kit.create_and_map_if(kit.control(), p, PROB_MIN, COUNT_UNKNOWN);
1892           Node* notnull = __ IfTrue(iff);
1893           Node* isnull =  __ IfFalse(iff);
1894           kit.set_control(notnull); // set control for the cast_not_null
1895           r->init_req(1, notnull);
1896           phi->init_req(1, kit.cast_not_null(arg, false));
1897           r->init_req(2, isnull);
1898           phi->init_req(2, null_string);
1899           kit.set_control(r);
1900           C->record_for_igvn(r);
1901           C->record_for_igvn(phi);
1902           // replace the argument with the null checked version
1903           arg = phi;
1904           sc->set_argument(argi, arg);
1905           count = kit.load_String_length(arg, true);
1906           arg_coder = kit.load_String_coder(arg, true);
1907         } else {
1908           // A corresponding nullcheck will be connected during IGVN MemNode::Ideal_common_DU_postCCP
1909           // kit.control might be a different test, that can be hoisted above the actual nullcheck
1910           // in case, that the control input is not null, Ideal_common_DU_postCCP will not look for a nullcheck.
1911           count = kit.load_String_length(arg, false);
1912           arg_coder = kit.load_String_coder(arg, false);
1913         }
1914         if (arg->is_Con()) {
1915           // Constant string. Get constant coder and length.
1916           jbyte const_coder = get_constant_coder(kit, arg);
1917           int const_length = get_constant_length(kit, arg);
1918           if (const_coder == java_lang_String::CODER_LATIN1) {
1919             // Can be latin1 encoded
1920             arg_coder = __ intcon(const_coder);
1921             count = __ intcon(const_length);
1922           } else {
1923             // Found UTF16 encoded string. Fix result array encoding to UTF16.
1924             coder_fixed = true;
1925             coder = __ intcon(const_coder);
1926             count = __ intcon(const_length / 2);
1927           }
1928         }
1929 
1930         if (!coder_fixed) {
1931           coder = __ OrI(coder, arg_coder);
1932         }
1933         length = __ AddI(length, count);
1934         string_sizes->init_req(argi, NULL);
1935         break;
1936       }
1937       case StringConcat::CharMode: {
1938         // one character only
1939         const TypeInt* t = kit.gvn().type(arg)->is_int();
1940         if (!coder_fixed && t->is_con()) {
1941           // Constant char
1942           if (t->get_con() <= 255) {
1943             // Can be latin1 encoded
1944             coder = __ OrI(coder, __ intcon(java_lang_String::CODER_LATIN1));
1945           } else {
1946             // Must be UTF16 encoded. Fix result array encoding to UTF16.
1947             coder_fixed = true;
1948             coder = __ intcon(java_lang_String::CODER_UTF16);
1949           }
1950         } else if (!coder_fixed) {
1951           // Not constant
1952 #undef __
1953 #define __ ideal.
1954           IdealKit ideal(&kit, true, true);
1955           IdealVariable char_coder(ideal); __ declarations_done();
1956           // Check if character can be latin1 encoded
1957           __ if_then(arg, BoolTest::le, __ ConI(0xFF));
1958             __ set(char_coder, __ ConI(java_lang_String::CODER_LATIN1));
1959           __ else_();
1960             __ set(char_coder, __ ConI(java_lang_String::CODER_UTF16));
1961           __ end_if();
1962           kit.sync_kit(ideal);
1963           coder = __ OrI(coder, __ value(char_coder));
1964 #undef __
1965 #define __ kit.
1966         }
1967         length = __ AddI(length, __ intcon(1));
1968         break;
1969       }
1970       default:
1971         ShouldNotReachHere();
1972     }
1973     if (argi > 0) {
1974       // Check that the sum hasn't overflowed
1975       IfNode* iff = kit.create_and_map_if(kit.control(),
1976                                           __ Bool(__ CmpI(length, __ intcon(0)), BoolTest::lt),
1977                                           PROB_MIN, COUNT_UNKNOWN);
1978       kit.set_control(__ IfFalse(iff));
1979       overflow->set_req(argi, __ IfTrue(iff));
1980     }
1981   }
1982 
1983   {
1984     // Hook
1985     PreserveJVMState pjvms(&kit);
1986     kit.set_control(overflow);
1987     C->record_for_igvn(overflow);
1988     kit.uncommon_trap(Deoptimization::Reason_intrinsic,
1989                       Deoptimization::Action_make_not_entrant);
1990   }
1991 
1992   Node* result;
1993   if (!kit.stopped()) {
1994     assert(CompactStrings || (coder->is_Con() && coder->get_int() == java_lang_String::CODER_UTF16),
1995            "Result string must be UTF16 encoded if CompactStrings is disabled");
1996 
1997     Node* dst_array = NULL;
1998     if (sc->num_arguments() == 1 &&
1999         (sc->mode(0) == StringConcat::StringMode ||
2000          sc->mode(0) == StringConcat::StringNullCheckMode)) {
2001       // Handle the case when there is only a single String argument.
2002       // In this case, we can just pull the value from the String itself.
2003       dst_array = kit.load_String_value(sc->argument(0), true);
2004     } else {
2005       // Allocate destination byte array according to coder
2006       dst_array = allocate_byte_array(kit, NULL, __ LShiftI(length, coder));
2007 
2008       // Now copy the string representations into the final byte[]
2009       Node* start = __ intcon(0);
2010       for (int argi = 0; argi < sc->num_arguments(); argi++) {
2011         Node* arg = sc->argument(argi);
2012         switch (sc->mode(argi)) {
2013           case StringConcat::NegativeIntCheckMode:
2014             break; // Nothing to do, was only needed to add a runtime check earlier.
2015           case StringConcat::IntMode: {
2016             start = int_getChars(kit, arg, dst_array, coder, start, string_sizes->in(argi));
2017             break;
2018           }
2019           case StringConcat::StringNullCheckMode:
2020           case StringConcat::StringMode: {
2021             start = copy_string(kit, arg, dst_array, coder, start);
2022             break;
2023           }
2024           case StringConcat::CharMode: {
2025             start = copy_char(kit, arg, dst_array, coder, start);
2026           break;
2027           }
2028           default:
2029             ShouldNotReachHere();
2030         }
2031       }
2032     }
2033 
2034     // If we're not reusing an existing String allocation then allocate one here.
2035     result = sc->string_alloc();
2036     if (result == NULL) {
2037       PreserveReexecuteState preexecs(&kit);
2038       // The original jvms is for an allocation of either a String or
2039       // StringBuffer so no stack adjustment is necessary for proper
2040       // reexecution.
2041       kit.jvms()->set_should_reexecute(true);
2042       result = kit.new_instance(__ makecon(TypeKlassPtr::make(C->env()->String_klass())));
2043     }
2044 
2045     // Initialize the string
2046     kit.store_String_value(result, dst_array);
2047     kit.store_String_coder(result, coder);
2048 
2049     // The value field is final. Emit a barrier here to ensure that the effect
2050     // of the initialization is committed to memory before any code publishes
2051     // a reference to the newly constructed object (see Parse::do_exits()).
2052     assert(AllocateNode::Ideal_allocation(result, _gvn) != NULL, "should be newly allocated");
2053     kit.insert_mem_bar(Op_MemBarRelease, result);
2054   } else {
2055     result = C->top();
2056   }
2057   // hook up the outgoing control and result
2058   kit.replace_call(sc->end(), result);
2059 
2060   // Unhook any hook nodes
2061   string_sizes->disconnect_inputs(C);
2062   sc->cleanup();
2063 }