stringopts.cpp 48.0 KB
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/*
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 * Copyright (c) 2009, 2010, Oracle and/or its affiliates. All rights reserved.
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
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 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
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 *
 */

#include "incls/_precompiled.incl"
#include "incls/_stringopts.cpp.incl"

#define __ kit.

class StringConcat : public ResourceObj {
 private:
  PhaseStringOpts*    _stringopts;
  Node*               _string_alloc;
  AllocateNode*       _begin;          // The allocation the begins the pattern
  CallStaticJavaNode* _end;            // The final call of the pattern.  Will either be
                                       // SB.toString or or String.<init>(SB.toString)
  bool                _multiple;       // indicates this is a fusion of two or more
                                       // separate StringBuilders

  Node*               _arguments;      // The list of arguments to be concatenated
  GrowableArray<int>  _mode;           // into a String along with a mode flag
                                       // indicating how to treat the value.

  Node_List           _control;        // List of control nodes that will be deleted
  Node_List           _uncommon_traps; // Uncommon traps that needs to be rewritten
                                       // to restart at the initial JVMState.
 public:
  // Mode for converting arguments to Strings
  enum {
    StringMode,
    IntMode,
    CharMode
  };

  StringConcat(PhaseStringOpts* stringopts, CallStaticJavaNode* end):
    _end(end),
    _begin(NULL),
    _multiple(false),
    _string_alloc(NULL),
    _stringopts(stringopts) {
    _arguments = new (_stringopts->C, 1) Node(1);
    _arguments->del_req(0);
  }

  bool validate_control_flow();

  void merge_add() {
#if 0
    // XXX This is place holder code for reusing an existing String
    // allocation but the logic for checking the state safety is
    // probably inadequate at the moment.
    CallProjections endprojs;
    sc->end()->extract_projections(&endprojs, false);
    if (endprojs.resproj != NULL) {
      for (SimpleDUIterator i(endprojs.resproj); i.has_next(); i.next()) {
        CallStaticJavaNode *use = i.get()->isa_CallStaticJava();
        if (use != NULL && use->method() != NULL &&
            use->method()->holder() == C->env()->String_klass() &&
            use->method()->name() == ciSymbol::object_initializer_name() &&
            use->in(TypeFunc::Parms + 1) == endprojs.resproj) {
          // Found useless new String(sb.toString()) so reuse the newly allocated String
          // when creating the result instead of allocating a new one.
          sc->set_string_alloc(use->in(TypeFunc::Parms));
          sc->set_end(use);
        }
      }
    }
#endif
  }

  StringConcat* merge(StringConcat* other, Node* arg);

  void set_allocation(AllocateNode* alloc) {
    _begin = alloc;
  }

  void append(Node* value, int mode) {
    _arguments->add_req(value);
    _mode.append(mode);
  }
  void push(Node* value, int mode) {
    _arguments->ins_req(0, value);
    _mode.insert_before(0, mode);
  }
  void push_string(Node* value) {
    push(value, StringMode);
  }
  void push_int(Node* value) {
    push(value, IntMode);
  }
  void push_char(Node* value) {
    push(value, CharMode);
  }

  Node* argument(int i) {
    return _arguments->in(i);
  }
  void set_argument(int i, Node* value) {
    _arguments->set_req(i, value);
  }
  int num_arguments() {
    return _mode.length();
  }
  int mode(int i) {
    return _mode.at(i);
  }
  void add_control(Node* ctrl) {
    assert(!_control.contains(ctrl), "only push once");
    _control.push(ctrl);
  }
  CallStaticJavaNode* end() { return _end; }
  AllocateNode* begin() { return _begin; }
  Node* string_alloc() { return _string_alloc; }

  void eliminate_unneeded_control();
  void eliminate_initialize(InitializeNode* init);
  void eliminate_call(CallNode* call);

  void maybe_log_transform() {
    CompileLog* log = _stringopts->C->log();
    if (log != NULL) {
      log->head("replace_string_concat arguments='%d' string_alloc='%d' multiple='%d'",
                num_arguments(),
                _string_alloc != NULL,
                _multiple);
      JVMState* p = _begin->jvms();
      while (p != NULL) {
        log->elem("jvms bci='%d' method='%d'", p->bci(), log->identify(p->method()));
        p = p->caller();
      }
      log->tail("replace_string_concat");
    }
  }

  void convert_uncommon_traps(GraphKit& kit, const JVMState* jvms) {
    for (uint u = 0; u < _uncommon_traps.size(); u++) {
      Node* uct = _uncommon_traps.at(u);

      // Build a new call using the jvms state of the allocate
T
twisti 已提交
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      address call_addr = SharedRuntime::uncommon_trap_blob()->entry_point();
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      const TypeFunc* call_type = OptoRuntime::uncommon_trap_Type();
      int size = call_type->domain()->cnt();
      const TypePtr* no_memory_effects = NULL;
      Compile* C = _stringopts->C;
      CallStaticJavaNode* call = new (C, size) CallStaticJavaNode(call_type, call_addr, "uncommon_trap",
                                                                  jvms->bci(), no_memory_effects);
      for (int e = 0; e < TypeFunc::Parms; e++) {
        call->init_req(e, uct->in(e));
      }
      // Set the trap request to record intrinsic failure if this trap
      // is taken too many times.  Ideally we would handle then traps by
      // doing the original bookkeeping in the MDO so that if it caused
      // the code to be thrown out we could still recompile and use the
      // optimization.  Failing the uncommon traps doesn't really mean
      // that the optimization is a bad idea but there's no other way to
      // do the MDO updates currently.
      int trap_request = Deoptimization::make_trap_request(Deoptimization::Reason_intrinsic,
                                                           Deoptimization::Action_make_not_entrant);
      call->init_req(TypeFunc::Parms, __ intcon(trap_request));
      kit.add_safepoint_edges(call);

      _stringopts->gvn()->transform(call);
      C->gvn_replace_by(uct, call);
      uct->disconnect_inputs(NULL);
    }
  }

  void cleanup() {
    // disconnect the hook node
    _arguments->disconnect_inputs(NULL);
  }
};


void StringConcat::eliminate_unneeded_control() {
  eliminate_initialize(begin()->initialization());
  for (uint i = 0; i < _control.size(); i++) {
    Node* n = _control.at(i);
    if (n->is_Call()) {
      if (n != _end) {
        eliminate_call(n->as_Call());
      }
    } else if (n->is_IfTrue()) {
      Compile* C = _stringopts->C;
      C->gvn_replace_by(n, n->in(0)->in(0));
      C->gvn_replace_by(n->in(0), C->top());
    }
  }
}


StringConcat* StringConcat::merge(StringConcat* other, Node* arg) {
  StringConcat* result = new StringConcat(_stringopts, _end);
  for (uint x = 0; x < _control.size(); x++) {
    Node* n = _control.at(x);
    if (n->is_Call()) {
      result->_control.push(n);
    }
  }
  for (uint x = 0; x < other->_control.size(); x++) {
    Node* n = other->_control.at(x);
    if (n->is_Call()) {
      result->_control.push(n);
    }
  }
  assert(result->_control.contains(other->_end), "what?");
  assert(result->_control.contains(_begin), "what?");
  for (int x = 0; x < num_arguments(); x++) {
    if (argument(x) == arg) {
      // replace the toString result with the all the arguments that
      // made up the other StringConcat
      for (int y = 0; y < other->num_arguments(); y++) {
        result->append(other->argument(y), other->mode(y));
      }
    } else {
      result->append(argument(x), mode(x));
    }
  }
  result->set_allocation(other->_begin);
  result->_multiple = true;
  return result;
}


void StringConcat::eliminate_call(CallNode* call) {
  Compile* C = _stringopts->C;
  CallProjections projs;
  call->extract_projections(&projs, false);
  if (projs.fallthrough_catchproj != NULL) {
    C->gvn_replace_by(projs.fallthrough_catchproj, call->in(TypeFunc::Control));
  }
  if (projs.fallthrough_memproj != NULL) {
    C->gvn_replace_by(projs.fallthrough_memproj, call->in(TypeFunc::Memory));
  }
  if (projs.catchall_memproj != NULL) {
    C->gvn_replace_by(projs.catchall_memproj, C->top());
  }
  if (projs.fallthrough_ioproj != NULL) {
    C->gvn_replace_by(projs.fallthrough_ioproj, call->in(TypeFunc::I_O));
  }
  if (projs.catchall_ioproj != NULL) {
    C->gvn_replace_by(projs.catchall_ioproj, C->top());
  }
  if (projs.catchall_catchproj != NULL) {
    // EA can't cope with the partially collapsed graph this
    // creates so put it on the worklist to be collapsed later.
    for (SimpleDUIterator i(projs.catchall_catchproj); i.has_next(); i.next()) {
      Node *use = i.get();
      int opc = use->Opcode();
      if (opc == Op_CreateEx || opc == Op_Region) {
        _stringopts->record_dead_node(use);
      }
    }
    C->gvn_replace_by(projs.catchall_catchproj, C->top());
  }
  if (projs.resproj != NULL) {
    C->gvn_replace_by(projs.resproj, C->top());
  }
  C->gvn_replace_by(call, C->top());
}

void StringConcat::eliminate_initialize(InitializeNode* init) {
  Compile* C = _stringopts->C;

  // Eliminate Initialize node.
  assert(init->outcnt() <= 2, "only a control and memory projection expected");
  assert(init->req() <= InitializeNode::RawStores, "no pending inits");
  Node *ctrl_proj = init->proj_out(TypeFunc::Control);
  if (ctrl_proj != NULL) {
    C->gvn_replace_by(ctrl_proj, init->in(TypeFunc::Control));
  }
  Node *mem_proj = init->proj_out(TypeFunc::Memory);
  if (mem_proj != NULL) {
    Node *mem = init->in(TypeFunc::Memory);
    C->gvn_replace_by(mem_proj, mem);
  }
  C->gvn_replace_by(init, C->top());
  init->disconnect_inputs(NULL);
}

Node_List PhaseStringOpts::collect_toString_calls() {
  Node_List string_calls;
  Node_List worklist;

  _visited.Clear();

  // Prime the worklist
  for (uint i = 1; i < C->root()->len(); i++) {
    Node* n = C->root()->in(i);
    if (n != NULL && !_visited.test_set(n->_idx)) {
      worklist.push(n);
    }
  }

  while (worklist.size() > 0) {
    Node* ctrl = worklist.pop();
    if (ctrl->is_CallStaticJava()) {
      CallStaticJavaNode* csj = ctrl->as_CallStaticJava();
      ciMethod* m = csj->method();
      if (m != NULL &&
          (m->intrinsic_id() == vmIntrinsics::_StringBuffer_toString ||
           m->intrinsic_id() == vmIntrinsics::_StringBuilder_toString)) {
        string_calls.push(csj);
      }
    }
    if (ctrl->in(0) != NULL && !_visited.test_set(ctrl->in(0)->_idx)) {
      worklist.push(ctrl->in(0));
    }
    if (ctrl->is_Region()) {
      for (uint i = 1; i < ctrl->len(); i++) {
        if (ctrl->in(i) != NULL && !_visited.test_set(ctrl->in(i)->_idx)) {
          worklist.push(ctrl->in(i));
        }
      }
    }
  }
  return string_calls;
}


StringConcat* PhaseStringOpts::build_candidate(CallStaticJavaNode* call) {
  ciMethod* m = call->method();
  ciSymbol* string_sig;
  ciSymbol* int_sig;
  ciSymbol* char_sig;
  if (m->holder() == C->env()->StringBuilder_klass()) {
    string_sig = ciSymbol::String_StringBuilder_signature();
    int_sig = ciSymbol::int_StringBuilder_signature();
    char_sig = ciSymbol::char_StringBuilder_signature();
  } else if (m->holder() == C->env()->StringBuffer_klass()) {
    string_sig = ciSymbol::String_StringBuffer_signature();
    int_sig = ciSymbol::int_StringBuffer_signature();
    char_sig = ciSymbol::char_StringBuffer_signature();
  } else {
    return NULL;
  }
#ifndef PRODUCT
  if (PrintOptimizeStringConcat) {
    tty->print("considering toString call in ");
    call->jvms()->dump_spec(tty); tty->cr();
  }
#endif

  StringConcat* sc = new StringConcat(this, call);

  AllocateNode* alloc = NULL;
  InitializeNode* init = NULL;

  // possible opportunity for StringBuilder fusion
  CallStaticJavaNode* cnode = call;
  while (cnode) {
    Node* recv = cnode->in(TypeFunc::Parms)->uncast();
    if (recv->is_Proj()) {
      recv = recv->in(0);
    }
    cnode = recv->isa_CallStaticJava();
    if (cnode == NULL) {
      alloc = recv->isa_Allocate();
      if (alloc == NULL) {
        break;
      }
      // Find the constructor call
      Node* result = alloc->result_cast();
      if (result == NULL || !result->is_CheckCastPP()) {
        // strange looking allocation
#ifndef PRODUCT
        if (PrintOptimizeStringConcat) {
          tty->print("giving up because allocation looks strange ");
          alloc->jvms()->dump_spec(tty); tty->cr();
        }
#endif
        break;
      }
      Node* constructor = NULL;
      for (SimpleDUIterator i(result); i.has_next(); i.next()) {
        CallStaticJavaNode *use = i.get()->isa_CallStaticJava();
        if (use != NULL && use->method() != NULL &&
            use->method()->name() == ciSymbol::object_initializer_name() &&
            use->method()->holder() == m->holder()) {
          // Matched the constructor.
          ciSymbol* sig = use->method()->signature()->as_symbol();
          if (sig == ciSymbol::void_method_signature() ||
              sig == ciSymbol::int_void_signature() ||
              sig == ciSymbol::string_void_signature()) {
            if (sig == ciSymbol::string_void_signature()) {
              // StringBuilder(String) so pick this up as the first argument
              assert(use->in(TypeFunc::Parms + 1) != NULL, "what?");
              sc->push_string(use->in(TypeFunc::Parms + 1));
            }
            // The int variant takes an initial size for the backing
            // array so just treat it like the void version.
            constructor = use;
          } else {
#ifndef PRODUCT
            if (PrintOptimizeStringConcat) {
              tty->print("unexpected constructor signature: %s", sig->as_utf8());
            }
#endif
          }
          break;
        }
      }
      if (constructor == NULL) {
        // couldn't find constructor
#ifndef PRODUCT
        if (PrintOptimizeStringConcat) {
          tty->print("giving up because couldn't find constructor ");
          alloc->jvms()->dump_spec(tty);
        }
#endif
        break;
      }

      // Walked all the way back and found the constructor call so see
      // if this call converted into a direct string concatenation.
      sc->add_control(call);
      sc->add_control(constructor);
      sc->add_control(alloc);
      sc->set_allocation(alloc);
      if (sc->validate_control_flow()) {
        return sc;
      } else {
        return NULL;
      }
    } else if (cnode->method() == NULL) {
      break;
    } else if (cnode->method()->holder() == m->holder() &&
               cnode->method()->name() == ciSymbol::append_name() &&
               (cnode->method()->signature()->as_symbol() == string_sig ||
                cnode->method()->signature()->as_symbol() == char_sig ||
                cnode->method()->signature()->as_symbol() == int_sig)) {
      sc->add_control(cnode);
      Node* arg = cnode->in(TypeFunc::Parms + 1);
      if (cnode->method()->signature()->as_symbol() == int_sig) {
        sc->push_int(arg);
      } else if (cnode->method()->signature()->as_symbol() == char_sig) {
        sc->push_char(arg);
      } else {
        if (arg->is_Proj() && arg->in(0)->is_CallStaticJava()) {
          CallStaticJavaNode* csj = arg->in(0)->as_CallStaticJava();
          if (csj->method() != NULL &&
              csj->method()->holder() == C->env()->Integer_klass() &&
              csj->method()->name() == ciSymbol::toString_name()) {
            sc->add_control(csj);
            sc->push_int(csj->in(TypeFunc::Parms));
            continue;
          }
        }
        sc->push_string(arg);
      }
      continue;
    } else {
      // some unhandled signature
#ifndef PRODUCT
      if (PrintOptimizeStringConcat) {
        tty->print("giving up because encountered unexpected signature ");
        cnode->tf()->dump(); tty->cr();
        cnode->in(TypeFunc::Parms + 1)->dump();
      }
#endif
      break;
    }
  }
  return NULL;
}


PhaseStringOpts::PhaseStringOpts(PhaseGVN* gvn, Unique_Node_List*):
  Phase(StringOpts),
  _gvn(gvn),
  _visited(Thread::current()->resource_area()) {

  assert(OptimizeStringConcat, "shouldn't be here");

  size_table_field = C->env()->Integer_klass()->get_field_by_name(ciSymbol::make("sizeTable"),
                                                                  ciSymbol::make("[I"), true);
  if (size_table_field == NULL) {
    // Something wrong so give up.
    assert(false, "why can't we find Integer.sizeTable?");
    return;
  }

  // Collect the types needed to talk about the various slices of memory
  const TypeInstPtr* string_type = TypeInstPtr::make(TypePtr::NotNull, C->env()->String_klass(),
                                                     false, NULL, 0);

  const TypePtr* value_field_type = string_type->add_offset(java_lang_String::value_offset_in_bytes());
  const TypePtr* offset_field_type = string_type->add_offset(java_lang_String::offset_offset_in_bytes());
  const TypePtr* count_field_type = string_type->add_offset(java_lang_String::count_offset_in_bytes());

  value_field_idx = C->get_alias_index(value_field_type);
  count_field_idx = C->get_alias_index(count_field_type);
  offset_field_idx = C->get_alias_index(offset_field_type);
  char_adr_idx = C->get_alias_index(TypeAryPtr::CHARS);

  // For each locally allocated StringBuffer see if the usages can be
  // collapsed into a single String construction.

  // Run through the list of allocation looking for SB.toString to see
  // if it's possible to fuse the usage of the SB into a single String
  // construction.
  GrowableArray<StringConcat*> concats;
  Node_List toStrings = collect_toString_calls();
  while (toStrings.size() > 0) {
    StringConcat* sc = build_candidate(toStrings.pop()->as_CallStaticJava());
    if (sc != NULL) {
      concats.push(sc);
    }
  }

  // try to coalesce separate concats
 restart:
  for (int c = 0; c < concats.length(); c++) {
    StringConcat* sc = concats.at(c);
    for (int i = 0; i < sc->num_arguments(); i++) {
      Node* arg = sc->argument(i);
      if (arg->is_Proj() && arg->in(0)->is_CallStaticJava()) {
        CallStaticJavaNode* csj = arg->in(0)->as_CallStaticJava();
        if (csj->method() != NULL &&
            (csj->method()->holder() == C->env()->StringBuffer_klass() ||
             csj->method()->holder() == C->env()->StringBuilder_klass()) &&
            csj->method()->name() == ciSymbol::toString_name()) {
          for (int o = 0; o < concats.length(); o++) {
            if (c == o) continue;
            StringConcat* other = concats.at(o);
            if (other->end() == csj) {
#ifndef PRODUCT
              if (PrintOptimizeStringConcat) {
                tty->print_cr("considering stacked concats");
              }
#endif

              StringConcat* merged = sc->merge(other, arg);
              if (merged->validate_control_flow()) {
#ifndef PRODUCT
                if (PrintOptimizeStringConcat) {
                  tty->print_cr("stacking would succeed");
                }
#endif
                if (c < o) {
                  concats.remove_at(o);
                  concats.at_put(c, merged);
                } else {
                  concats.remove_at(c);
                  concats.at_put(o, merged);
                }
                goto restart;
              } else {
#ifndef PRODUCT
                if (PrintOptimizeStringConcat) {
                  tty->print_cr("stacking would fail");
                }
#endif
              }
            }
          }
        }
      }
    }
  }


  for (int c = 0; c < concats.length(); c++) {
    StringConcat* sc = concats.at(c);
    replace_string_concat(sc);
  }

  remove_dead_nodes();
}

void PhaseStringOpts::record_dead_node(Node* dead) {
  dead_worklist.push(dead);
}

void PhaseStringOpts::remove_dead_nodes() {
  // Delete any dead nodes to make things clean enough that escape
  // analysis doesn't get unhappy.
  while (dead_worklist.size() > 0) {
    Node* use = dead_worklist.pop();
    int opc = use->Opcode();
    switch (opc) {
      case Op_Region: {
        uint i = 1;
        for (i = 1; i < use->req(); i++) {
          if (use->in(i) != C->top()) {
            break;
          }
        }
        if (i >= use->req()) {
          for (SimpleDUIterator i(use); i.has_next(); i.next()) {
            Node* m = i.get();
            if (m->is_Phi()) {
              dead_worklist.push(m);
            }
          }
          C->gvn_replace_by(use, C->top());
        }
        break;
      }
      case Op_AddP:
      case Op_CreateEx: {
        // Recurisvely clean up references to CreateEx so EA doesn't
        // get unhappy about the partially collapsed graph.
        for (SimpleDUIterator i(use); i.has_next(); i.next()) {
          Node* m = i.get();
          if (m->is_AddP()) {
            dead_worklist.push(m);
          }
        }
        C->gvn_replace_by(use, C->top());
        break;
      }
      case Op_Phi:
        if (use->in(0) == C->top()) {
          C->gvn_replace_by(use, C->top());
        }
        break;
    }
  }
}


bool StringConcat::validate_control_flow() {
  // We found all the calls and arguments now lets see if it's
  // safe to transform the graph as we would expect.

  // Check to see if this resulted in too many uncommon traps previously
  if (Compile::current()->too_many_traps(_begin->jvms()->method(), _begin->jvms()->bci(),
                        Deoptimization::Reason_intrinsic)) {
    return false;
  }

  // Walk backwards over the control flow from toString to the
  // allocation and make sure all the control flow is ok.  This
  // means it's either going to be eliminated once the calls are
  // removed or it can safely be transformed into an uncommon
  // trap.

  int null_check_count = 0;
  Unique_Node_List ctrl_path;

  assert(_control.contains(_begin), "missing");
  assert(_control.contains(_end), "missing");

  // Collect the nodes that we know about and will eliminate into ctrl_path
  for (uint i = 0; i < _control.size(); i++) {
    // Push the call and it's control projection
    Node* n = _control.at(i);
    if (n->is_Allocate()) {
      AllocateNode* an = n->as_Allocate();
      InitializeNode* init = an->initialization();
      ctrl_path.push(init);
      ctrl_path.push(init->as_Multi()->proj_out(0));
    }
    if (n->is_Call()) {
      CallNode* cn = n->as_Call();
      ctrl_path.push(cn);
      ctrl_path.push(cn->proj_out(0));
      ctrl_path.push(cn->proj_out(0)->unique_out());
      ctrl_path.push(cn->proj_out(0)->unique_out()->as_Catch()->proj_out(0));
    } else {
      ShouldNotReachHere();
    }
  }

  // Skip backwards through the control checking for unexpected contro flow
  Node* ptr = _end;
  bool fail = false;
  while (ptr != _begin) {
    if (ptr->is_Call() && ctrl_path.member(ptr)) {
      ptr = ptr->in(0);
    } else if (ptr->is_CatchProj() && ctrl_path.member(ptr)) {
      ptr = ptr->in(0)->in(0)->in(0);
      assert(ctrl_path.member(ptr), "should be a known piece of control");
    } else if (ptr->is_IfTrue()) {
      IfNode* iff = ptr->in(0)->as_If();
      BoolNode* b = iff->in(1)->isa_Bool();
      Node* cmp = b->in(1);
      Node* v1 = cmp->in(1);
      Node* v2 = cmp->in(2);
      Node* otherproj = iff->proj_out(1 - ptr->as_Proj()->_con);

      // Null check of the return of append which can simply be eliminated
      if (b->_test._test == BoolTest::ne &&
          v2->bottom_type() == TypePtr::NULL_PTR &&
          v1->is_Proj() && ctrl_path.member(v1->in(0))) {
        // NULL check of the return value of the append
        null_check_count++;
        if (otherproj->outcnt() == 1) {
          CallStaticJavaNode* call = otherproj->unique_out()->isa_CallStaticJava();
          if (call != NULL && call->_name != NULL && strcmp(call->_name, "uncommon_trap") == 0) {
            ctrl_path.push(call);
          }
        }
        _control.push(ptr);
        ptr = ptr->in(0)->in(0);
        continue;
      }

      // A test which leads to an uncommon trap which should be safe.
      // Later this trap will be converted into a trap that restarts
      // at the beginning.
      if (otherproj->outcnt() == 1) {
        CallStaticJavaNode* call = otherproj->unique_out()->isa_CallStaticJava();
        if (call != NULL && call->_name != NULL && strcmp(call->_name, "uncommon_trap") == 0) {
          // control flow leads to uct so should be ok
          _uncommon_traps.push(call);
          ctrl_path.push(call);
          ptr = ptr->in(0)->in(0);
          continue;
        }
      }

#ifndef PRODUCT
      // Some unexpected control flow we don't know how to handle.
      if (PrintOptimizeStringConcat) {
        tty->print_cr("failing with unknown test");
        b->dump();
        cmp->dump();
        v1->dump();
        v2->dump();
        tty->cr();
      }
#endif
      break;
    } else if (ptr->is_Proj() && ptr->in(0)->is_Initialize()) {
      ptr = ptr->in(0)->in(0);
    } else if (ptr->is_Region()) {
      Node* copy = ptr->as_Region()->is_copy();
      if (copy != NULL) {
        ptr = copy;
        continue;
      }
      if (ptr->req() == 3 &&
          ptr->in(1) != NULL && ptr->in(1)->is_Proj() &&
          ptr->in(2) != NULL && ptr->in(2)->is_Proj() &&
          ptr->in(1)->in(0) == ptr->in(2)->in(0) &&
          ptr->in(1)->in(0) != NULL && ptr->in(1)->in(0)->is_If()) {
        // Simple diamond.
        // XXX should check for possibly merging stores.  simple data merges are ok.
        ptr = ptr->in(1)->in(0)->in(0);
        continue;
      }
#ifndef PRODUCT
      if (PrintOptimizeStringConcat) {
        tty->print_cr("fusion would fail for region");
        _begin->dump();
        ptr->dump(2);
      }
#endif
      fail = true;
      break;
    } else {
      // other unknown control
      if (!fail) {
#ifndef PRODUCT
        if (PrintOptimizeStringConcat) {
          tty->print_cr("fusion would fail for");
          _begin->dump();
        }
#endif
        fail = true;
      }
#ifndef PRODUCT
      if (PrintOptimizeStringConcat) {
        ptr->dump();
      }
#endif
      ptr = ptr->in(0);
    }
  }
#ifndef PRODUCT
  if (PrintOptimizeStringConcat && fail) {
    tty->cr();
  }
#endif
  if (fail) return !fail;

  // Validate that all these results produced are contained within
  // this cluster of objects.  First collect all the results produced
  // by calls in the region.
  _stringopts->_visited.Clear();
  Node_List worklist;
  Node* final_result = _end->proj_out(TypeFunc::Parms);
  for (uint i = 0; i < _control.size(); i++) {
    CallNode* cnode = _control.at(i)->isa_Call();
    if (cnode != NULL) {
      _stringopts->_visited.test_set(cnode->_idx);
    }
    Node* result = cnode != NULL ? cnode->proj_out(TypeFunc::Parms) : NULL;
    if (result != NULL && result != final_result) {
      worklist.push(result);
    }
  }

  Node* last_result = NULL;
  while (worklist.size() > 0) {
    Node* result = worklist.pop();
    if (_stringopts->_visited.test_set(result->_idx))
      continue;
    for (SimpleDUIterator i(result); i.has_next(); i.next()) {
      Node *use = i.get();
      if (ctrl_path.member(use)) {
        // already checked this
        continue;
      }
      int opc = use->Opcode();
      if (opc == Op_CmpP || opc == Op_Node) {
        ctrl_path.push(use);
        continue;
      }
      if (opc == Op_CastPP || opc == Op_CheckCastPP) {
        for (SimpleDUIterator j(use); j.has_next(); j.next()) {
          worklist.push(j.get());
        }
        worklist.push(use->in(1));
        ctrl_path.push(use);
        continue;
      }
#ifndef PRODUCT
      if (PrintOptimizeStringConcat) {
        if (result != last_result) {
          last_result = result;
          tty->print_cr("extra uses for result:");
          last_result->dump();
        }
        use->dump();
      }
#endif
      fail = true;
      break;
    }
  }

#ifndef PRODUCT
  if (PrintOptimizeStringConcat && !fail) {
    ttyLocker ttyl;
    tty->cr();
    tty->print("fusion would succeed (%d %d) for ", null_check_count, _uncommon_traps.size());
    _begin->jvms()->dump_spec(tty); tty->cr();
    for (int i = 0; i < num_arguments(); i++) {
      argument(i)->dump();
    }
    _control.dump();
    tty->cr();
  }
#endif

  return !fail;
}

Node* PhaseStringOpts::fetch_static_field(GraphKit& kit, ciField* field) {
  const TypeKlassPtr* klass_type = TypeKlassPtr::make(field->holder());
  Node* klass_node = __ makecon(klass_type);
  BasicType bt = field->layout_type();
  ciType* field_klass = field->type();

  const Type *type;
  if( bt == T_OBJECT ) {
    if (!field->type()->is_loaded()) {
      type = TypeInstPtr::BOTTOM;
    } else if (field->is_constant()) {
      // This can happen if the constant oop is non-perm.
      ciObject* con = field->constant_value().as_object();
      // Do not "join" in the previous type; it doesn't add value,
      // and may yield a vacuous result if the field is of interface type.
      type = TypeOopPtr::make_from_constant(con)->isa_oopptr();
      assert(type != NULL, "field singleton type must be consistent");
    } else {
      type = TypeOopPtr::make_from_klass(field_klass->as_klass());
    }
  } else {
    type = Type::get_const_basic_type(bt);
  }

  return kit.make_load(NULL, kit.basic_plus_adr(klass_node, field->offset_in_bytes()),
                       type, T_OBJECT,
                       C->get_alias_index(klass_type->add_offset(field->offset_in_bytes())));
}

Node* PhaseStringOpts::int_stringSize(GraphKit& kit, Node* arg) {
  RegionNode *final_merge = new (C, 3) RegionNode(3);
  kit.gvn().set_type(final_merge, Type::CONTROL);
  Node* final_size = new (C, 3) PhiNode(final_merge, TypeInt::INT);
  kit.gvn().set_type(final_size, TypeInt::INT);

  IfNode* iff = kit.create_and_map_if(kit.control(),
                                      __ Bool(__ CmpI(arg, __ intcon(0x80000000)), BoolTest::ne),
                                      PROB_FAIR, COUNT_UNKNOWN);
  Node* is_min = __ IfFalse(iff);
  final_merge->init_req(1, is_min);
  final_size->init_req(1, __ intcon(11));

  kit.set_control(__ IfTrue(iff));
  if (kit.stopped()) {
    final_merge->init_req(2, C->top());
    final_size->init_req(2, C->top());
  } else {

    // int size = (i < 0) ? stringSize(-i) + 1 : stringSize(i);
    RegionNode *r = new (C, 3) RegionNode(3);
    kit.gvn().set_type(r, Type::CONTROL);
    Node *phi = new (C, 3) PhiNode(r, TypeInt::INT);
    kit.gvn().set_type(phi, TypeInt::INT);
    Node *size = new (C, 3) PhiNode(r, TypeInt::INT);
    kit.gvn().set_type(size, TypeInt::INT);
    Node* chk = __ CmpI(arg, __ intcon(0));
    Node* p = __ Bool(chk, BoolTest::lt);
    IfNode* iff = kit.create_and_map_if(kit.control(), p, PROB_FAIR, COUNT_UNKNOWN);
    Node* lessthan = __ IfTrue(iff);
    Node* greaterequal = __ IfFalse(iff);
    r->init_req(1, lessthan);
    phi->init_req(1, __ SubI(__ intcon(0), arg));
    size->init_req(1, __ intcon(1));
    r->init_req(2, greaterequal);
    phi->init_req(2, arg);
    size->init_req(2, __ intcon(0));
    kit.set_control(r);
    C->record_for_igvn(r);
    C->record_for_igvn(phi);
    C->record_for_igvn(size);

    // for (int i=0; ; i++)
    //   if (x <= sizeTable[i])
    //     return i+1;
    RegionNode *loop = new (C, 3) RegionNode(3);
    loop->init_req(1, kit.control());
    kit.gvn().set_type(loop, Type::CONTROL);

    Node *index = new (C, 3) PhiNode(loop, TypeInt::INT);
    index->init_req(1, __ intcon(0));
    kit.gvn().set_type(index, TypeInt::INT);
    kit.set_control(loop);
    Node* sizeTable = fetch_static_field(kit, size_table_field);

    Node* value = kit.load_array_element(NULL, sizeTable, index, TypeAryPtr::INTS);
    C->record_for_igvn(value);
    Node* limit = __ CmpI(phi, value);
    Node* limitb = __ Bool(limit, BoolTest::le);
    IfNode* iff2 = kit.create_and_map_if(kit.control(), limitb, PROB_MIN, COUNT_UNKNOWN);
    Node* lessEqual = __ IfTrue(iff2);
    Node* greater = __ IfFalse(iff2);

    loop->init_req(2, greater);
    index->init_req(2, __ AddI(index, __ intcon(1)));

    kit.set_control(lessEqual);
    C->record_for_igvn(loop);
    C->record_for_igvn(index);

    final_merge->init_req(2, kit.control());
    final_size->init_req(2, __ AddI(__ AddI(index, size), __ intcon(1)));
  }

  kit.set_control(final_merge);
  C->record_for_igvn(final_merge);
  C->record_for_igvn(final_size);

  return final_size;
}

void PhaseStringOpts::int_getChars(GraphKit& kit, Node* arg, Node* char_array, Node* start, Node* end) {
  RegionNode *final_merge = new (C, 4) RegionNode(4);
  kit.gvn().set_type(final_merge, Type::CONTROL);
  Node *final_mem = PhiNode::make(final_merge, kit.memory(char_adr_idx), Type::MEMORY, TypeAryPtr::CHARS);
  kit.gvn().set_type(final_mem, Type::MEMORY);

  // need to handle Integer.MIN_VALUE specially because negating doesn't make it positive
  {
    // i == MIN_VALUE
    IfNode* iff = kit.create_and_map_if(kit.control(),
                                        __ Bool(__ CmpI(arg, __ intcon(0x80000000)), BoolTest::ne),
                                        PROB_FAIR, COUNT_UNKNOWN);

    Node* old_mem = kit.memory(char_adr_idx);

    kit.set_control(__ IfFalse(iff));
    if (kit.stopped()) {
      // Statically not equal to MIN_VALUE so this path is dead
      final_merge->init_req(3, kit.control());
    } else {
      copy_string(kit, __ makecon(TypeInstPtr::make(C->env()->the_min_jint_string())),
                  char_array, start);
      final_merge->init_req(3, kit.control());
      final_mem->init_req(3, kit.memory(char_adr_idx));
    }

    kit.set_control(__ IfTrue(iff));
    kit.set_memory(old_mem, char_adr_idx);
  }


  // Simplified version of Integer.getChars

  // int q, r;
  // int charPos = index;
  Node* charPos = end;

  // char sign = 0;

  Node* i = arg;
  Node* sign = __ intcon(0);

  // if (i < 0) {
  //     sign = '-';
  //     i = -i;
  // }
  {
    IfNode* iff = kit.create_and_map_if(kit.control(),
                                        __ Bool(__ CmpI(arg, __ intcon(0)), BoolTest::lt),
                                        PROB_FAIR, COUNT_UNKNOWN);

    RegionNode *merge = new (C, 3) RegionNode(3);
    kit.gvn().set_type(merge, Type::CONTROL);
    i = new (C, 3) PhiNode(merge, TypeInt::INT);
    kit.gvn().set_type(i, TypeInt::INT);
    sign = new (C, 3) PhiNode(merge, TypeInt::INT);
    kit.gvn().set_type(sign, TypeInt::INT);

    merge->init_req(1, __ IfTrue(iff));
    i->init_req(1, __ SubI(__ intcon(0), arg));
    sign->init_req(1, __ intcon('-'));
    merge->init_req(2, __ IfFalse(iff));
    i->init_req(2, arg);
    sign->init_req(2, __ intcon(0));

    kit.set_control(merge);

    C->record_for_igvn(merge);
    C->record_for_igvn(i);
    C->record_for_igvn(sign);
  }

  // for (;;) {
  //     q = i / 10;
  //     r = i - ((q << 3) + (q << 1));  // r = i-(q*10) ...
  //     buf [--charPos] = digits [r];
  //     i = q;
  //     if (i == 0) break;
  // }

  {
    RegionNode *head = new (C, 3) RegionNode(3);
    head->init_req(1, kit.control());
    kit.gvn().set_type(head, Type::CONTROL);
    Node *i_phi = new (C, 3) PhiNode(head, TypeInt::INT);
    i_phi->init_req(1, i);
    kit.gvn().set_type(i_phi, TypeInt::INT);
    charPos = PhiNode::make(head, charPos);
    kit.gvn().set_type(charPos, TypeInt::INT);
    Node *mem = PhiNode::make(head, kit.memory(char_adr_idx), Type::MEMORY, TypeAryPtr::CHARS);
    kit.gvn().set_type(mem, Type::MEMORY);
    kit.set_control(head);
    kit.set_memory(mem, char_adr_idx);

1076
    Node* q = __ DivI(NULL, i_phi, __ intcon(10));
1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272
    Node* r = __ SubI(i_phi, __ AddI(__ LShiftI(q, __ intcon(3)),
                                     __ LShiftI(q, __ intcon(1))));
    Node* m1 = __ SubI(charPos, __ intcon(1));
    Node* ch = __ AddI(r, __ intcon('0'));

    Node* st = __ store_to_memory(kit.control(), kit.array_element_address(char_array, m1, T_CHAR),
                                  ch, T_CHAR, char_adr_idx);


    IfNode* iff = kit.create_and_map_if(head, __ Bool(__ CmpI(q, __ intcon(0)), BoolTest::ne),
                                        PROB_FAIR, COUNT_UNKNOWN);
    Node* ne = __ IfTrue(iff);
    Node* eq = __ IfFalse(iff);

    head->init_req(2, ne);
    mem->init_req(2, st);
    i_phi->init_req(2, q);
    charPos->init_req(2, m1);

    charPos = m1;

    kit.set_control(eq);
    kit.set_memory(st, char_adr_idx);

    C->record_for_igvn(head);
    C->record_for_igvn(mem);
    C->record_for_igvn(i_phi);
    C->record_for_igvn(charPos);
  }

  {
    // if (sign != 0) {
    //     buf [--charPos] = sign;
    // }
    IfNode* iff = kit.create_and_map_if(kit.control(),
                                        __ Bool(__ CmpI(sign, __ intcon(0)), BoolTest::ne),
                                        PROB_FAIR, COUNT_UNKNOWN);

    final_merge->init_req(2, __ IfFalse(iff));
    final_mem->init_req(2, kit.memory(char_adr_idx));

    kit.set_control(__ IfTrue(iff));
    if (kit.stopped()) {
      final_merge->init_req(1, C->top());
      final_mem->init_req(1, C->top());
    } else {
      Node* m1 = __ SubI(charPos, __ intcon(1));
      Node* st = __ store_to_memory(kit.control(), kit.array_element_address(char_array, m1, T_CHAR),
                                    sign, T_CHAR, char_adr_idx);

      final_merge->init_req(1, kit.control());
      final_mem->init_req(1, st);
    }

    kit.set_control(final_merge);
    kit.set_memory(final_mem, char_adr_idx);

    C->record_for_igvn(final_merge);
    C->record_for_igvn(final_mem);
  }
}


Node* PhaseStringOpts::copy_string(GraphKit& kit, Node* str, Node* char_array, Node* start) {
  Node* string = str;
  Node* offset = kit.make_load(NULL,
                               kit.basic_plus_adr(string, string, java_lang_String::offset_offset_in_bytes()),
                               TypeInt::INT, T_INT, offset_field_idx);
  Node* count = kit.make_load(NULL,
                              kit.basic_plus_adr(string, string, java_lang_String::count_offset_in_bytes()),
                              TypeInt::INT, T_INT, count_field_idx);
  const TypeAryPtr*  value_type = TypeAryPtr::make(TypePtr::NotNull,
                                                   TypeAry::make(TypeInt::CHAR,TypeInt::POS),
                                                   ciTypeArrayKlass::make(T_CHAR), true, 0);
  Node* value = kit.make_load(NULL,
                              kit.basic_plus_adr(string, string, java_lang_String::value_offset_in_bytes()),
                              value_type, T_OBJECT, value_field_idx);

  // copy the contents
  if (offset->is_Con() && count->is_Con() && value->is_Con() && count->get_int() < unroll_string_copy_length) {
    // For small constant strings just emit individual stores.
    // A length of 6 seems like a good space/speed tradeof.
    int c = count->get_int();
    int o = offset->get_int();
    const TypeOopPtr* t = kit.gvn().type(value)->isa_oopptr();
    ciTypeArray* value_array = t->const_oop()->as_type_array();
    for (int e = 0; e < c; e++) {
      __ store_to_memory(kit.control(), kit.array_element_address(char_array, start, T_CHAR),
                         __ intcon(value_array->char_at(o + e)), T_CHAR, char_adr_idx);
      start = __ AddI(start, __ intcon(1));
    }
  } else {
    Node* src_ptr = kit.array_element_address(value, offset, T_CHAR);
    Node* dst_ptr = kit.array_element_address(char_array, start, T_CHAR);
    Node* c = count;
    Node* extra = NULL;
#ifdef _LP64
    c = __ ConvI2L(c);
    extra = C->top();
#endif
    Node* call = kit.make_runtime_call(GraphKit::RC_LEAF|GraphKit::RC_NO_FP,
                                       OptoRuntime::fast_arraycopy_Type(),
                                       CAST_FROM_FN_PTR(address, StubRoutines::jshort_disjoint_arraycopy()),
                                       "jshort_disjoint_arraycopy", TypeAryPtr::CHARS,
                                       src_ptr, dst_ptr, c, extra);
    start = __ AddI(start, count);
  }
  return start;
}


void PhaseStringOpts::replace_string_concat(StringConcat* sc) {
  // Log a little info about the transformation
  sc->maybe_log_transform();

  // pull the JVMState of the allocation into a SafePointNode to serve as
  // as a shim for the insertion of the new code.
  JVMState* jvms     = sc->begin()->jvms()->clone_shallow(C);
  uint size = sc->begin()->req();
  SafePointNode* map = new (C, size) SafePointNode(size, jvms);

  // copy the control and memory state from the final call into our
  // new starting state.  This allows any preceeding tests to feed
  // into the new section of code.
  for (uint i1 = 0; i1 < TypeFunc::Parms; i1++) {
    map->init_req(i1, sc->end()->in(i1));
  }
  // blow away old allocation arguments
  for (uint i1 = TypeFunc::Parms; i1 < jvms->debug_start(); i1++) {
    map->init_req(i1, C->top());
  }
  // Copy the rest of the inputs for the JVMState
  for (uint i1 = jvms->debug_start(); i1 < sc->begin()->req(); i1++) {
    map->init_req(i1, sc->begin()->in(i1));
  }
  // Make sure the memory state is a MergeMem for parsing.
  if (!map->in(TypeFunc::Memory)->is_MergeMem()) {
    map->set_req(TypeFunc::Memory, MergeMemNode::make(C, map->in(TypeFunc::Memory)));
  }

  jvms->set_map(map);
  map->ensure_stack(jvms, jvms->method()->max_stack());


  // disconnect all the old StringBuilder calls from the graph
  sc->eliminate_unneeded_control();

  // At this point all the old work has been completely removed from
  // the graph and the saved JVMState exists at the point where the
  // final toString call used to be.
  GraphKit kit(jvms);

  // There may be uncommon traps which are still using the
  // intermediate states and these need to be rewritten to point at
  // the JVMState at the beginning of the transformation.
  sc->convert_uncommon_traps(kit, jvms);

  // Now insert the logic to compute the size of the string followed
  // by all the logic to construct array and resulting string.

  Node* null_string = __ makecon(TypeInstPtr::make(C->env()->the_null_string()));

  // Create a region for the overflow checks to merge into.
  int args = MAX2(sc->num_arguments(), 1);
  RegionNode* overflow = new (C, args) RegionNode(args);
  kit.gvn().set_type(overflow, Type::CONTROL);

  // Create a hook node to hold onto the individual sizes since they
  // are need for the copying phase.
  Node* string_sizes = new (C, args) Node(args);

  Node* length = __ intcon(0);
  for (int argi = 0; argi < sc->num_arguments(); argi++) {
    Node* arg = sc->argument(argi);
    switch (sc->mode(argi)) {
      case StringConcat::IntMode: {
        Node* string_size = int_stringSize(kit, arg);

        // accumulate total
        length = __ AddI(length, string_size);

        // Cache this value for the use by int_toString
        string_sizes->init_req(argi, string_size);
        break;
      }
      case StringConcat::StringMode: {
        const Type* type = kit.gvn().type(arg);
        if (type == TypePtr::NULL_PTR) {
          // replace the argument with the null checked version
          arg = null_string;
          sc->set_argument(argi, arg);
        } else if (!type->higher_equal(TypeInstPtr::NOTNULL)) {
          // s = s != null ? s : "null";
          // length = length + (s.count - s.offset);
          RegionNode *r = new (C, 3) RegionNode(3);
          kit.gvn().set_type(r, Type::CONTROL);
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          Node *phi = new (C, 3) PhiNode(r, type);
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          kit.gvn().set_type(phi, phi->bottom_type());
          Node* p = __ Bool(__ CmpP(arg, kit.null()), BoolTest::ne);
          IfNode* iff = kit.create_and_map_if(kit.control(), p, PROB_MIN, COUNT_UNKNOWN);
          Node* notnull = __ IfTrue(iff);
          Node* isnull =  __ IfFalse(iff);
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          kit.set_control(notnull); // set control for the cast_not_null
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          r->init_req(1, notnull);
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          phi->init_req(1, kit.cast_not_null(arg, false));
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          r->init_req(2, isnull);
          phi->init_req(2, null_string);
          kit.set_control(r);
          C->record_for_igvn(r);
          C->record_for_igvn(phi);
          // replace the argument with the null checked version
          arg = phi;
          sc->set_argument(argi, arg);
        }
        //         Node* offset = kit.make_load(NULL, kit.basic_plus_adr(arg, arg, offset_offset),
        //                                      TypeInt::INT, T_INT, offset_field_idx);
        Node* count = kit.make_load(NULL, kit.basic_plus_adr(arg, arg, java_lang_String::count_offset_in_bytes()),
                                    TypeInt::INT, T_INT, count_field_idx);
        length = __ AddI(length, count);
        string_sizes->init_req(argi, NULL);
        break;
      }
      case StringConcat::CharMode: {
        // one character only
        length = __ AddI(length, __ intcon(1));
        break;
      }
      default:
        ShouldNotReachHere();
    }
    if (argi > 0) {
      // Check that the sum hasn't overflowed
      IfNode* iff = kit.create_and_map_if(kit.control(),
                                          __ Bool(__ CmpI(length, __ intcon(0)), BoolTest::lt),
                                          PROB_MIN, COUNT_UNKNOWN);
      kit.set_control(__ IfFalse(iff));
      overflow->set_req(argi, __ IfTrue(iff));
    }
  }

  {
    // Hook
    PreserveJVMState pjvms(&kit);
    kit.set_control(overflow);
    kit.uncommon_trap(Deoptimization::Reason_intrinsic,
                      Deoptimization::Action_make_not_entrant);
  }

  // length now contains the number of characters needed for the
  // char[] so create a new AllocateArray for the char[]
  Node* char_array = NULL;
  {
    PreserveReexecuteState preexecs(&kit);
    // The original jvms is for an allocation of either a String or
    // StringBuffer so no stack adjustment is necessary for proper
    // reexecution.  If we deoptimize in the slow path the bytecode
    // will be reexecuted and the char[] allocation will be thrown away.
    kit.jvms()->set_should_reexecute(true);
    char_array = kit.new_array(__ makecon(TypeKlassPtr::make(ciTypeArrayKlass::make(T_CHAR))),
                               length, 1);
  }

  // Mark the allocation so that zeroing is skipped since the code
  // below will overwrite the entire array
  AllocateArrayNode* char_alloc = AllocateArrayNode::Ideal_array_allocation(char_array, _gvn);
  char_alloc->maybe_set_complete(_gvn);

  // Now copy the string representations into the final char[]
  Node* start = __ intcon(0);
  for (int argi = 0; argi < sc->num_arguments(); argi++) {
    Node* arg = sc->argument(argi);
    switch (sc->mode(argi)) {
      case StringConcat::IntMode: {
        Node* end = __ AddI(start, string_sizes->in(argi));
        // getChars words backwards so pass the ending point as well as the start
        int_getChars(kit, arg, char_array, start, end);
        start = end;
        break;
      }
      case StringConcat::StringMode: {
        start = copy_string(kit, arg, char_array, start);
        break;
      }
      case StringConcat::CharMode: {
        __ store_to_memory(kit.control(), kit.array_element_address(char_array, start, T_CHAR),
                           arg, T_CHAR, char_adr_idx);
        start = __ AddI(start, __ intcon(1));
        break;
      }
      default:
        ShouldNotReachHere();
    }
  }

  // If we're not reusing an existing String allocation then allocate one here.
  Node* result = sc->string_alloc();
  if (result == NULL) {
    PreserveReexecuteState preexecs(&kit);
    // The original jvms is for an allocation of either a String or
    // StringBuffer so no stack adjustment is necessary for proper
    // reexecution.
    kit.jvms()->set_should_reexecute(true);
    result = kit.new_instance(__ makecon(TypeKlassPtr::make(C->env()->String_klass())));
  }

  // Intialize the string
  kit.store_to_memory(kit.control(), kit.basic_plus_adr(result, java_lang_String::offset_offset_in_bytes()),
                      __ intcon(0), T_INT, offset_field_idx);
  kit.store_to_memory(kit.control(), kit.basic_plus_adr(result, java_lang_String::count_offset_in_bytes()),
                      length, T_INT, count_field_idx);
  kit.store_to_memory(kit.control(), kit.basic_plus_adr(result, java_lang_String::value_offset_in_bytes()),
                      char_array, T_OBJECT, value_field_idx);

  // hook up the outgoing control and result
  kit.replace_call(sc->end(), result);

  // Unhook any hook nodes
  string_sizes->disconnect_inputs(NULL);
  sc->cleanup();
}