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 /*

  * Copyright 2000-2008 Sun Microsystems, Inc.  All Rights Reserved.

  * 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.

  *

  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

  * CA 95054 USA or visit www.sun.com if you need additional information or

  * have any questions.

  *

  */

 #include "incls/_precompiled.incl"

 #include "incls/_ciTypeFlow.cpp.incl"

 // ciTypeFlow::JsrSet

 //

 // A JsrSet represents some set of JsrRecords.  This class

 // is used to record a set of all jsr routines which we permit

 // execution to return (ret) from.

 //

 // During abstract interpretation, JsrSets are used to determine

 // whether two paths which reach a given block are unique, and

 // should be cloned apart, or are compatible, and should merge

 // together.

 // ------------------------------------------------------------------

 // ciTypeFlow::JsrSet::JsrSet

 ciTypeFlow::JsrSet::JsrSet(Arena* arena, int default_len) {

   if (arena != NULL) {

     // Allocate growable array in Arena.

     _set = new (arena) GrowableArray<JsrRecord*>(arena, default_len, 0, NULL);

   } else {

     // Allocate growable array in current ResourceArea.

     _set = new GrowableArray<JsrRecord*>(4, 0, NULL, false);

   }

 }

 // ------------------------------------------------------------------

 // ciTypeFlow::JsrSet::copy_into

 void ciTypeFlow::JsrSet::copy_into(JsrSet* jsrs) {

   int len = size();

   jsrs->_set->clear();

   for (int i = 0; i < len; i++) {

     jsrs->_set->append(_set->at(i));

   }

 }

 // ------------------------------------------------------------------

 // ciTypeFlow::JsrSet::is_compatible_with

 //

 // !!!! MISGIVINGS ABOUT THIS... disregard

 //

 // Is this JsrSet compatible with some other JsrSet?

 //

 // In set-theoretic terms, a JsrSet can be viewed as a partial function

 // from entry addresses to return addresses.  Two JsrSets A and B are

 // compatible iff

 //

 //   For any x,

 //   A(x) defined and B(x) defined implies A(x) == B(x)

 //

 // Less formally, two JsrSets are compatible when they have identical

 // return addresses for any entry addresses they share in common.

 bool ciTypeFlow::JsrSet::is_compatible_with(JsrSet* other) {

   // Walk through both sets in parallel.  If the same entry address

   // appears in both sets, then the return address must match for

   // the sets to be compatible.

   int size1 = size();

   int size2 = other->size();

   // Special case.  If nothing is on the jsr stack, then there can

   // be no ret.

   if (size2 == 0) {

     return true;

   } else if (size1 != size2) {

     return false;

   } else {

     for (int i = 0; i < size1; i++) {

       JsrRecord* record1 = record_at(i);

       JsrRecord* record2 = other->record_at(i);

       if (record1->entry_address() != record2->entry_address() ||

           record1->return_address() != record2->return_address()) {

         return false;

       }

     }

     return true;

   }

 #if 0

   int pos1 = 0;

   int pos2 = 0;

   int size1 = size();

   int size2 = other->size();

   while (pos1 < size1 && pos2 < size2) {

     JsrRecord* record1 = record_at(pos1);

     JsrRecord* record2 = other->record_at(pos2);

     int entry1 = record1->entry_address();

     int entry2 = record2->entry_address();

     if (entry1 < entry2) {

       pos1++;

     } else if (entry1 > entry2) {

       pos2++;

     } else {

       if (record1->return_address() == record2->return_address()) {

         pos1++;

         pos2++;

       } else {

         // These two JsrSets are incompatible.

         return false;

       }

     }

   }

   // The two JsrSets agree.

   return true;

 #endif

 }

 // ------------------------------------------------------------------

 // ciTypeFlow::JsrSet::insert_jsr_record

 //

 // Insert the given JsrRecord into the JsrSet, maintaining the order

 // of the set and replacing any element with the same entry address.

 void ciTypeFlow::JsrSet::insert_jsr_record(JsrRecord* record) {

   int len = size();

   int entry = record->entry_address();

   int pos = 0;

   for ( ; pos < len; pos++) {

     JsrRecord* current = record_at(pos);

     if (entry == current->entry_address()) {

       // Stomp over this entry.

       _set->at_put(pos, record);

       assert(size() == len, "must be same size");

       return;

     } else if (entry < current->entry_address()) {

       break;

     }

   }

   // Insert the record into the list.

   JsrRecord* swap = record;

   JsrRecord* temp = NULL;

   for ( ; pos < len; pos++) {

     temp = _set->at(pos);

     _set->at_put(pos, swap);

     swap = temp;

   }

   _set->append(swap);

   assert(size() == len+1, "must be larger");

 }

 // ------------------------------------------------------------------

 // ciTypeFlow::JsrSet::remove_jsr_record

 //

 // Remove the JsrRecord with the given return address from the JsrSet.

 void ciTypeFlow::JsrSet::remove_jsr_record(int return_address) {

   int len = size();

   for (int i = 0; i < len; i++) {

     if (record_at(i)->return_address() == return_address) {

       // We have found the proper entry.  Remove it from the

       // JsrSet and exit.

       for (int j = i+1; j < len ; j++) {

         _set->at_put(j-1, _set->at(j));

       }

       _set->trunc_to(len-1);

       assert(size() == len-1, "must be smaller");

       return;

     }

   }

   assert(false, "verify: returning from invalid subroutine");

 }

 // ------------------------------------------------------------------

 // ciTypeFlow::JsrSet::apply_control

 //

 // Apply the effect of a control-flow bytecode on the JsrSet.  The

 // only bytecodes that modify the JsrSet are jsr and ret.

 void ciTypeFlow::JsrSet::apply_control(ciTypeFlow* analyzer,

                                        ciBytecodeStream* str,

                                        ciTypeFlow::StateVector* state) {

   Bytecodes::Code code = str->cur_bc();

   if (code == Bytecodes::_jsr) {

     JsrRecord* record =

       analyzer->make_jsr_record(str->get_dest(), str->next_bci());

     insert_jsr_record(record);

   } else if (code == Bytecodes::_jsr_w) {

     JsrRecord* record =

       analyzer->make_jsr_record(str->get_far_dest(), str->next_bci());

     insert_jsr_record(record);

   } else if (code == Bytecodes::_ret) {

     Cell local = state->local(str->get_index());

     ciType* return_address = state->type_at(local);

     assert(return_address->is_return_address(), "verify: wrong type");

     if (size() == 0) {

       // Ret-state underflow:  Hit a ret w/o any previous jsrs.  Bail out.

       // This can happen when a loop is inside a finally clause (4614060).

       analyzer->record_failure("OSR in finally clause");

       return;

     }

     remove_jsr_record(return_address->as_return_address()->bci());

   }

 }

 #ifndef PRODUCT

 // ------------------------------------------------------------------

 // ciTypeFlow::JsrSet::print_on

 void ciTypeFlow::JsrSet::print_on(outputStream* st) const {

   st->print("{ ");

   int num_elements = size();

   if (num_elements > 0) {

     int i = 0;

     for( ; i < num_elements - 1; i++) {

       _set->at(i)->print_on(st);

       st->print(", ");

     }

     _set->at(i)->print_on(st);

     st->print(" ");

   }

   st->print("}");

 }

 #endif

 // ciTypeFlow::StateVector

 //

 // A StateVector summarizes the type information at some point in

 // the program.

 // ------------------------------------------------------------------

 // ciTypeFlow::StateVector::type_meet

 //

 // Meet two types.

 //

 // The semi-lattice of types use by this analysis are modeled on those

 // of the verifier.  The lattice is as follows:

 //

 //        top_type() >= all non-extremal types >= bottom_type

 //                             and

 //   Every primitive type is comparable only with itself.  The meet of

 //   reference types is determined by their kind: instance class,

 //   interface, or array class.  The meet of two types of the same

 //   kind is their least common ancestor.  The meet of two types of

 //   different kinds is always java.lang.Object.

 ciType* ciTypeFlow::StateVector::type_meet_internal(ciType* t1, ciType* t2, ciTypeFlow* analyzer) {

   assert(t1 != t2, "checked in caller");

   if (t1->equals(top_type())) {

     return t2;

   } else if (t2->equals(top_type())) {

     return t1;

   } else if (t1->is_primitive_type() || t2->is_primitive_type()) {

     // Special case null_type.  null_type meet any reference type T

     // is T.  null_type meet null_type is null_type.

     if (t1->equals(null_type())) {

       if (!t2->is_primitive_type() || t2->equals(null_type())) {

         return t2;

       }

     } else if (t2->equals(null_type())) {

       if (!t1->is_primitive_type()) {

         return t1;

       }

     }

     // At least one of the two types is a non-top primitive type.

     // The other type is not equal to it.  Fall to bottom.

     return bottom_type();

   } else {

     // Both types are non-top non-primitive types.  That is,

     // both types are either instanceKlasses or arrayKlasses.

     ciKlass* object_klass = analyzer->env()->Object_klass();

     ciKlass* k1 = t1->as_klass();

     ciKlass* k2 = t2->as_klass();

     if (k1->equals(object_klass) || k2->equals(object_klass)) {

       return object_klass;

     } else if (!k1->is_loaded() || !k2->is_loaded()) {

       // Unloaded classes fall to java.lang.Object at a merge.

       return object_klass;

     } else if (k1->is_interface() != k2->is_interface()) {

       // When an interface meets a non-interface, we get Object;

       // This is what the verifier does.

       return object_klass;

     } else if (k1->is_array_klass() || k2->is_array_klass()) {

       // When an array meets a non-array, we get Object.

       // When objArray meets typeArray, we also get Object.

       // And when typeArray meets different typeArray, we again get Object.

       // But when objArray meets objArray, we look carefully at element types.

       if (k1->is_obj_array_klass() && k2->is_obj_array_klass()) {

         // Meet the element types, then construct the corresponding array type.

         ciKlass* elem1 = k1->as_obj_array_klass()->element_klass();

         ciKlass* elem2 = k2->as_obj_array_klass()->element_klass();

         ciKlass* elem  = type_meet_internal(elem1, elem2, analyzer)->as_klass();

         // Do an easy shortcut if one type is a super of the other.

         if (elem == elem1) {

           assert(k1 == ciObjArrayKlass::make(elem), "shortcut is OK");

           return k1;

         } else if (elem == elem2) {

           assert(k2 == ciObjArrayKlass::make(elem), "shortcut is OK");

           return k2;

         } else {

           return ciObjArrayKlass::make(elem);

         }

       } else {

         return object_klass;

       }

     } else {

       // Must be two plain old instance klasses.

       assert(k1->is_instance_klass(), "previous cases handle non-instances");

       assert(k2->is_instance_klass(), "previous cases handle non-instances");

       return k1->least_common_ancestor(k2);

     }

   }

 }

 // ------------------------------------------------------------------

 // ciTypeFlow::StateVector::StateVector

 //

 // Build a new state vector

 ciTypeFlow::StateVector::StateVector(ciTypeFlow* analyzer) {

   _outer = analyzer;

   _stack_size = -1;

   _monitor_count = -1;

   // Allocate the _types array

   int max_cells = analyzer->max_cells();

   _types = (ciType**)analyzer->arena()->Amalloc(sizeof(ciType*) * max_cells);

   for (int i=0; i<max_cells; i++) {

     _types[i] = top_type();

   }

   _trap_bci = -1;

   _trap_index = 0;

   _def_locals.clear();

 }

 // ------------------------------------------------------------------

 // ciTypeFlow::get_start_state

 //

 // Set this vector to the method entry state.

 const ciTypeFlow::StateVector* ciTypeFlow::get_start_state() {

   StateVector* state = new StateVector(this);

   if (is_osr_flow()) {

     ciTypeFlow* non_osr_flow = method()->get_flow_analysis();

     if (non_osr_flow->failing()) {

       record_failure(non_osr_flow->failure_reason());

       return NULL;

     }

     JsrSet* jsrs = new JsrSet(NULL, 16);

     Block* non_osr_block = non_osr_flow->existing_block_at(start_bci(), jsrs);

     if (non_osr_block == NULL) {

       record_failure("cannot reach OSR point");

       return NULL;

     }

     // load up the non-OSR state at this point

     non_osr_block->copy_state_into(state);

     int non_osr_start = non_osr_block->start();

     if (non_osr_start != start_bci()) {

       // must flow forward from it

       if (CITraceTypeFlow) {

         tty->print_cr(">> Interpreting pre-OSR block %d:", non_osr_start);

       }

       Block* block = block_at(non_osr_start, jsrs);

       assert(block->limit() == start_bci(), "must flow forward to start");

       flow_block(block, state, jsrs);

     }

     return state;

     // Note:  The code below would be an incorrect for an OSR flow,

     // even if it were possible for an OSR entry point to be at bci zero.

   }

   // "Push" the method signature into the first few locals.

   state->set_stack_size(-max_locals());

   if (!method()->is_static()) {

     state->push(method()->holder());

     assert(state->tos() == state->local(0), "");

   }

   for (ciSignatureStream str(method()->signature());

        !str.at_return_type();

        str.next()) {

     state->push_translate(str.type());

   }

   // Set the rest of the locals to bottom.

   Cell cell = state->next_cell(state->tos());

   state->set_stack_size(0);

   int limit = state->limit_cell();

   for (; cell < limit; cell = state->next_cell(cell)) {

     state->set_type_at(cell, state->bottom_type());

   }

   // Lock an object, if necessary.

   state->set_monitor_count(method()->is_synchronized() ? 1 : 0);

   return state;

 }

 // ------------------------------------------------------------------

 // ciTypeFlow::StateVector::copy_into

 //

 // Copy our value into some other StateVector

 void ciTypeFlow::StateVector::copy_into(ciTypeFlow::StateVector* copy)

 const {

   copy->set_stack_size(stack_size());

   copy->set_monitor_count(monitor_count());

   Cell limit = limit_cell();

   for (Cell c = start_cell(); c < limit; c = next_cell(c)) {

     copy->set_type_at(c, type_at(c));

   }

 }

 // ------------------------------------------------------------------

 // ciTypeFlow::StateVector::meet

 //

 // Meets this StateVector with another, destructively modifying this

 // one.  Returns true if any modification takes place.

 bool ciTypeFlow::StateVector::meet(const ciTypeFlow::StateVector* incoming) {

   if (monitor_count() == -1) {

     set_monitor_count(incoming->monitor_count());

   }

   assert(monitor_count() == incoming->monitor_count(), "monitors must match");

   if (stack_size() == -1) {

     set_stack_size(incoming->stack_size());

     Cell limit = limit_cell();

     #ifdef ASSERT

     { for (Cell c = start_cell(); c < limit; c = next_cell(c)) {

         assert(type_at(c) == top_type(), "");

     } }

     #endif

     // Make a simple copy of the incoming state.

     for (Cell c = start_cell(); c < limit; c = next_cell(c)) {

       set_type_at(c, incoming->type_at(c));

     }

     return true;  // it is always different the first time

   }

 #ifdef ASSERT

   if (stack_size() != incoming->stack_size()) {

     _outer->method()->print_codes();

     tty->print_cr("!!!! Stack size conflict");

     tty->print_cr("Current state:");

     print_on(tty);

     tty->print_cr("Incoming state:");

     ((StateVector*)incoming)->print_on(tty);

   }

 #endif

   assert(stack_size() == incoming->stack_size(), "sanity");

   bool different = false;

   Cell limit = limit_cell();

   for (Cell c = start_cell(); c < limit; c = next_cell(c)) {

     ciType* t1 = type_at(c);

     ciType* t2 = incoming->type_at(c);

     if (!t1->equals(t2)) {

       ciType* new_type = type_meet(t1, t2);

       if (!t1->equals(new_type)) {

         set_type_at(c, new_type);

         different = true;

       }

     }

   }

   return different;

 }

 // ------------------------------------------------------------------

 // ciTypeFlow::StateVector::meet_exception

 //

 // Meets this StateVector with another, destructively modifying this

 // one.  The incoming state is coming via an exception.  Returns true

 // if any modification takes place.

 bool ciTypeFlow::StateVector::meet_exception(ciInstanceKlass* exc,

                                      const ciTypeFlow::StateVector* incoming) {

   if (monitor_count() == -1) {

     set_monitor_count(incoming->monitor_count());

   }

   assert(monitor_count() == incoming->monitor_count(), "monitors must match");

   if (stack_size() == -1) {

     set_stack_size(1);

   }

   assert(stack_size() ==  1, "must have one-element stack");

   bool different = false;

   // Meet locals from incoming array.

   Cell limit = local(_outer->max_locals()-1);

   for (Cell c = start_cell(); c <= limit; c = next_cell(c)) {

     ciType* t1 = type_at(c);

     ciType* t2 = incoming->type_at(c);

     if (!t1->equals(t2)) {

       ciType* new_type = type_meet(t1, t2);

       if (!t1->equals(new_type)) {

         set_type_at(c, new_type);

         different = true;

       }

     }

   }

   // Handle stack separately.  When an exception occurs, the

   // only stack entry is the exception instance.

   ciType* tos_type = type_at_tos();

   if (!tos_type->equals(exc)) {

     ciType* new_type = type_meet(tos_type, exc);

     if (!tos_type->equals(new_type)) {

       set_type_at_tos(new_type);

       different = true;

     }

   }

   return different;

 }

 // ------------------------------------------------------------------

 // ciTypeFlow::StateVector::push_translate

 void ciTypeFlow::StateVector::push_translate(ciType* type) {

   BasicType basic_type = type->basic_type();

   if (basic_type == T_BOOLEAN || basic_type == T_CHAR ||

       basic_type == T_BYTE    || basic_type == T_SHORT) {

     push_int();

   } else {

     push(type);

     if (type->is_two_word()) {

       push(half_type(type));

     }

   }

 }

 // ------------------------------------------------------------------

 // ciTypeFlow::StateVector::do_aaload

 void ciTypeFlow::StateVector::do_aaload(ciBytecodeStream* str) {

   pop_int();

   ciObjArrayKlass* array_klass = pop_objArray();

   if (array_klass == NULL) {

     // Did aaload on a null reference; push a null and ignore the exception.

     // This instruction will never continue normally.  All we have to do

     // is report a value that will meet correctly with any downstream

     // reference types on paths that will truly be executed.  This null type

     // meets with any reference type to yield that same reference type.

     // (The compiler will generate an unconditional exception here.)

     push(null_type());

     return;

   }

   if (!array_klass->is_loaded()) {

     // Only fails for some -Xcomp runs

     trap(str, array_klass,

          Deoptimization::make_trap_request

          (Deoptimization::Reason_unloaded,

           Deoptimization::Action_reinterpret));

     return;

   }

   ciKlass* element_klass = array_klass->element_klass();

   if (!element_klass->is_loaded() && element_klass->is_instance_klass()) {

     Untested("unloaded array element class in ciTypeFlow");

     trap(str, element_klass,

          Deoptimization::make_trap_request

          (Deoptimization::Reason_unloaded,

           Deoptimization::Action_reinterpret));

   } else {

     push_object(element_klass);

   }

 }

 // ------------------------------------------------------------------

 // ciTypeFlow::StateVector::do_checkcast

 void ciTypeFlow::StateVector::do_checkcast(ciBytecodeStream* str) {

   bool will_link;

   ciKlass* klass = str->get_klass(will_link);

   if (!will_link) {

     // VM's interpreter will not load 'klass' if object is NULL.

     // Type flow after this block may still be needed in two situations:

     // 1) C2 uses do_null_assert() and continues compilation for later blocks

     // 2) C2 does an OSR compile in a later block (see bug 4778368).

     pop_object();

     do_null_assert(klass);

   } else {

     pop_object();

     push_object(klass);

   }

 }

 // ------------------------------------------------------------------

 // ciTypeFlow::StateVector::do_getfield

 void ciTypeFlow::StateVector::do_getfield(ciBytecodeStream* str) {

   // could add assert here for type of object.

   pop_object();

   do_getstatic(str);

 }

 // ------------------------------------------------------------------

 // ciTypeFlow::StateVector::do_getstatic

 void ciTypeFlow::StateVector::do_getstatic(ciBytecodeStream* str) {

   bool will_link;

   ciField* field = str->get_field(will_link);

   if (!will_link) {

     trap(str, field->holder(), str->get_field_holder_index());

   } else {

     ciType* field_type = field->type();

     if (!field_type->is_loaded()) {

       // Normally, we need the field's type to be loaded if we are to

       // do anything interesting with its value.

       // We used to do this:  trap(str, str->get_field_signature_index());

       //

       // There is one good reason not to trap here.  Execution can

       // get past this "getfield" or "getstatic" if the value of

       // the field is null.  As long as the value is null, the class

       // does not need to be loaded!  The compiler must assume that

       // the value of the unloaded class reference is null; if the code

       // ever sees a non-null value, loading has occurred.

       //

       // This actually happens often enough to be annoying.  If the

       // compiler throws an uncommon trap at this bytecode, you can

       // get an endless loop of recompilations, when all the code

       // needs to do is load a series of null values.  Also, a trap

       // here can make an OSR entry point unreachable, triggering the

       // assert on non_osr_block in ciTypeFlow::get_start_state.

       // (See bug 4379915.)

       do_null_assert(field_type->as_klass());

     } else {

       push_translate(field_type);

     }

   }

 }

 // ------------------------------------------------------------------

 // ciTypeFlow::StateVector::do_invoke

 void ciTypeFlow::StateVector::do_invoke(ciBytecodeStream* str,

                                         bool has_receiver) {

   bool will_link;

   ciMethod* method = str->get_method(will_link);

   if (!will_link) {

     // We weren't able to find the method.

     ciKlass* unloaded_holder = method->holder();

     trap(str, unloaded_holder, str->get_method_holder_index());

   } else {

     ciSignature* signature = method->signature();

     ciSignatureStream sigstr(signature);

     int arg_size = signature->size();

     int stack_base = stack_size() - arg_size;

     int i = 0;

     for( ; !sigstr.at_return_type(); sigstr.next()) {

       ciType* type = sigstr.type();

       ciType* stack_type = type_at(stack(stack_base + i++));

       // Do I want to check this type?

       // assert(stack_type->is_subtype_of(type), "bad type for field value");

       if (type->is_two_word()) {

         ciType* stack_type2 = type_at(stack(stack_base + i++));

         assert(stack_type2->equals(half_type(type)), "must be 2nd half");

       }

     }

     assert(arg_size == i, "must match");

     for (int j = 0; j < arg_size; j++) {

       pop();

     }

     if (has_receiver) {

       // Check this?

       pop_object();

     }

     assert(!sigstr.is_done(), "must have return type");

     ciType* return_type = sigstr.type();

     if (!return_type->is_void()) {

       if (!return_type->is_loaded()) {

         // As in do_getstatic(), generally speaking, we need the return type to

         // be loaded if we are to do anything interesting with its value.

         // We used to do this:  trap(str, str->get_method_signature_index());

         //

         // We do not trap here since execution can get past this invoke if

         // the return value is null.  As long as the value is null, the class

         // does not need to be loaded!  The compiler must assume that

         // the value of the unloaded class reference is null; if the code

         // ever sees a non-null value, loading has occurred.

         //

         // See do_getstatic() for similar explanation, as well as bug 4684993.

         do_null_assert(return_type->as_klass());

       } else {

         push_translate(return_type);

       }

     }

   }

 }

 // ------------------------------------------------------------------

 // ciTypeFlow::StateVector::do_jsr

 void ciTypeFlow::StateVector::do_jsr(ciBytecodeStream* str) {

   push(ciReturnAddress::make(str->next_bci()));

 }

 // ------------------------------------------------------------------

 // ciTypeFlow::StateVector::do_ldc

 void ciTypeFlow::StateVector::do_ldc(ciBytecodeStream* str) {

   ciConstant con = str->get_constant();

   BasicType basic_type = con.basic_type();

   if (basic_type == T_ILLEGAL) {

     // OutOfMemoryError in the CI while loading constant

     push_null();

     outer()->record_failure("ldc did not link");

     return;

   }

   if (basic_type == T_OBJECT || basic_type == T_ARRAY) {

     ciObject* obj = con.as_object();

     if (obj->is_null_object()) {

       push_null();

     } else if (obj->is_klass()) {

       // The type of ldc <class> is java.lang.Class

       push_object(outer()->env()->Class_klass());

     } else {

       push_object(obj->klass());

     }

   } else {

     push_translate(ciType::make(basic_type));

   }

 }

 // ------------------------------------------------------------------

 // ciTypeFlow::StateVector::do_multianewarray

 void ciTypeFlow::StateVector::do_multianewarray(ciBytecodeStream* str) {

   int dimensions = str->get_dimensions();

   bool will_link;

   ciArrayKlass* array_klass = str->get_klass(will_link)->as_array_klass();

   if (!will_link) {

     trap(str, array_klass, str->get_klass_index());

   } else {

     for (int i = 0; i < dimensions; i++) {

       pop_int();

     }

     push_object(array_klass);

   }

 }

 // ------------------------------------------------------------------

 // ciTypeFlow::StateVector::do_new

 void ciTypeFlow::StateVector::do_new(ciBytecodeStream* str) {

   bool will_link;

   ciKlass* klass = str->get_klass(will_link);

   if (!will_link || str->is_unresolved_klass()) {

     trap(str, klass, str->get_klass_index());

   } else {

     push_object(klass);

   }

 }

 // ------------------------------------------------------------------

 // ciTypeFlow::StateVector::do_newarray

 void ciTypeFlow::StateVector::do_newarray(ciBytecodeStream* str) {

   pop_int();

   ciKlass* klass = ciTypeArrayKlass::make((BasicType)str->get_index());

   push_object(klass);

 }

 // ------------------------------------------------------------------

 // ciTypeFlow::StateVector::do_putfield

 void ciTypeFlow::StateVector::do_putfield(ciBytecodeStream* str) {

   do_putstatic(str);

   if (_trap_bci != -1)  return;  // unloaded field holder, etc.

   // could add assert here for type of object.

   pop_object();

 }

 // ------------------------------------------------------------------

 // ciTypeFlow::StateVector::do_putstatic

 void ciTypeFlow::StateVector::do_putstatic(ciBytecodeStream* str) {

   bool will_link;

   ciField* field = str->get_field(will_link);

   if (!will_link) {

     trap(str, field->holder(), str->get_field_holder_index());

   } else {

     ciType* field_type = field->type();

     ciType* type = pop_value();

     // Do I want to check this type?

     //      assert(type->is_subtype_of(field_type), "bad type for field value");

     if (field_type->is_two_word()) {

       ciType* type2 = pop_value();

       assert(type2->is_two_word(), "must be 2nd half");

       assert(type == half_type(type2), "must be 2nd half");

     }

   }

 }

 // ------------------------------------------------------------------

 // ciTypeFlow::StateVector::do_ret

 void ciTypeFlow::StateVector::do_ret(ciBytecodeStream* str) {

   Cell index = local(str->get_index());

   ciType* address = type_at(index);

   assert(address->is_return_address(), "bad return address");

   set_type_at(index, bottom_type());

 }

 // ------------------------------------------------------------------

 // ciTypeFlow::StateVector::trap

 //

 // Stop interpretation of this path with a trap.

 void ciTypeFlow::StateVector::trap(ciBytecodeStream* str, ciKlass* klass, int index) {

   _trap_bci = str->cur_bci();

   _trap_index = index;

   // Log information about this trap:

   CompileLog* log = outer()->env()->log();

   if (log != NULL) {

     int mid = log->identify(outer()->method());

     int kid = (klass == NULL)? -1: log->identify(klass);

     log->begin_elem("uncommon_trap method='%d' bci='%d'", mid, str->cur_bci());

     char buf[100];

     log->print(" %s", Deoptimization::format_trap_request(buf, sizeof(buf),

                                                           index));

     if (kid >= 0)

       log->print(" klass='%d'", kid);

     log->end_elem();

   }

 }

 // ------------------------------------------------------------------

 // ciTypeFlow::StateVector::do_null_assert

 // Corresponds to graphKit::do_null_assert.

 void ciTypeFlow::StateVector::do_null_assert(ciKlass* unloaded_klass) {

   if (unloaded_klass->is_loaded()) {

     // We failed to link, but we can still compute with this class,

     // since it is loaded somewhere.  The compiler will uncommon_trap

     // if the object is not null, but the typeflow pass can not assume

     // that the object will be null, otherwise it may incorrectly tell

     // the parser that an object is known to be null. 4761344, 4807707

     push_object(unloaded_klass);

   } else {

     // The class is not loaded anywhere.  It is safe to model the

     // null in the typestates, because we can compile in a null check

     // which will deoptimize us if someone manages to load the

     // class later.

     push_null();

   }

 }

 // ------------------------------------------------------------------

 // ciTypeFlow::StateVector::apply_one_bytecode

 //

 // Apply the effect of one bytecode to this StateVector

 bool ciTypeFlow::StateVector::apply_one_bytecode(ciBytecodeStream* str) {

   _trap_bci = -1;

   _trap_index = 0;

   if (CITraceTypeFlow) {

     tty->print_cr(">> Interpreting bytecode %d:%s", str->cur_bci(),

                   Bytecodes::name(str->cur_bc()));

   }

   switch(str->cur_bc()) {

   case Bytecodes::_aaload: do_aaload(str);                       break;

   case Bytecodes::_aastore:

     {

       pop_object();

       pop_int();

       pop_objArray();

       break;

     }

   case Bytecodes::_aconst_null:

     {

       push_null();

       break;

     }

   case Bytecodes::_aload:   load_local_object(str->get_index());    break;

   case Bytecodes::_aload_0: load_local_object(0);                   break;

   case Bytecodes::_aload_1: load_local_object(1);                   break;

   case Bytecodes::_aload_2: load_local_object(2);                   break;

   case Bytecodes::_aload_3: load_local_object(3);                   break;

   case Bytecodes::_anewarray:

     {

       pop_int();

       bool will_link;

       ciKlass* element_klass = str->get_klass(will_link);

       if (!will_link) {

         trap(str, element_klass, str->get_klass_index());

       } else {

         push_object(ciObjArrayKlass::make(element_klass));

       }

       break;

     }

   case Bytecodes::_areturn:

   case Bytecodes::_ifnonnull:

   case Bytecodes::_ifnull:

     {

       pop_object();

       break;

     }

   case Bytecodes::_monitorenter:

     {

       pop_object();

       set_monitor_count(monitor_count() + 1);

       break;

     }

   case Bytecodes::_monitorexit:

     {

       pop_object();

       assert(monitor_count() > 0, "must be a monitor to exit from");

       set_monitor_count(monitor_count() - 1);

       break;

     }

   case Bytecodes::_arraylength:

     {

       pop_array();

       push_int();

       break;

     }

   case Bytecodes::_astore:   store_local_object(str->get_index());  break;

   case Bytecodes::_astore_0: store_local_object(0);                 break;

   case Bytecodes::_astore_1: store_local_object(1);                 break;

   case Bytecodes::_astore_2: store_local_object(2);                 break;

   case Bytecodes::_astore_3: store_local_object(3);                 break;

   case Bytecodes::_athrow:

     {

       NEEDS_CLEANUP;

       pop_object();

       break;

     }

   case Bytecodes::_baload:

   case Bytecodes::_caload:

   case Bytecodes::_iaload:

   case Bytecodes::_saload:

     {

       pop_int();

       ciTypeArrayKlass* array_klass = pop_typeArray();

       // Put assert here for right type?

       push_int();

       break;

     }

   case Bytecodes::_bastore:

   case Bytecodes::_castore:

   case Bytecodes::_iastore:

   case Bytecodes::_sastore:

     {

       pop_int();

       pop_int();

       pop_typeArray();

       // assert here?

       break;

     }

   case Bytecodes::_bipush:

   case Bytecodes::_iconst_m1:

   case Bytecodes::_iconst_0:

   case Bytecodes::_iconst_1:

   case Bytecodes::_iconst_2:

   case Bytecodes::_iconst_3:

   case Bytecodes::_iconst_4:

   case Bytecodes::_iconst_5:

   case Bytecodes::_sipush:

     {

       push_int();

       break;

     }

   case Bytecodes::_checkcast: do_checkcast(str);                  break;

   case Bytecodes::_d2f:

     {

       pop_double();

       push_float();

       break;

     }

   case Bytecodes::_d2i:

     {

       pop_double();

       push_int();

       break;

     }

   case Bytecodes::_d2l:

     {

       pop_double();

       push_long();

       break;

     }

   case Bytecodes::_dadd:

   case Bytecodes::_ddiv:

   case Bytecodes::_dmul:

   case Bytecodes::_drem:

   case Bytecodes::_dsub:

     {

       pop_double();

       pop_double();

       push_double();

       break;

     }

   case Bytecodes::_daload:

     {

       pop_int();

       ciTypeArrayKlass* array_klass = pop_typeArray();

       // Put assert here for right type?

       push_double();

       break;

     }

   case Bytecodes::_dastore:

     {

       pop_double();

       pop_int();

       pop_typeArray();

       // assert here?

       break;

     }

   case Bytecodes::_dcmpg:

   case Bytecodes::_dcmpl:

     {

       pop_double();

       pop_double();

       push_int();

       break;

     }

   case Bytecodes::_dconst_0:

   case Bytecodes::_dconst_1:

     {

       push_double();

       break;

     }

   case Bytecodes::_dload:   load_local_double(str->get_index());    break;

   case Bytecodes::_dload_0: load_local_double(0);                   break;

   case Bytecodes::_dload_1: load_local_double(1);                   break;

   case Bytecodes::_dload_2: load_local_double(2);                   break;

   case Bytecodes::_dload_3: load_local_double(3);                   break;

   case Bytecodes::_dneg:

     {

       pop_double();

       push_double();

       break;

     }

   case Bytecodes::_dreturn:

     {

       pop_double();

       break;

     }

   case Bytecodes::_dstore:   store_local_double(str->get_index());  break;

   case Bytecodes::_dstore_0: store_local_double(0);                 break;

   case Bytecodes::_dstore_1: store_local_double(1);                 break;

   case Bytecodes::_dstore_2: store_local_double(2);                 break;

   case Bytecodes::_dstore_3: store_local_double(3);                 break;

   case Bytecodes::_dup:

     {

       push(type_at_tos());

       break;

     }

   case Bytecodes::_dup_x1:

     {

       ciType* value1 = pop_value();

       ciType* value2 = pop_value();

       push(value1);

       push(value2);

       push(value1);

       break;

     }

   case Bytecodes::_dup_x2:

     {

       ciType* value1 = pop_value();

       ciType* value2 = pop_value();

       ciType* value3 = pop_value();

       push(value1);

       push(value3);

       push(value2);

       push(value1);

       break;

     }

   case Bytecodes::_dup2:

     {

       ciType* value1 = pop_value();

       ciType* value2 = pop_value();

       push(value2);

       push(value1);

       push(value2);

       push(value1);

       break;

     }

   case Bytecodes::_dup2_x1:

     {

       ciType* value1 = pop_value();

       ciType* value2 = pop_value();

       ciType* value3 = pop_value();

       push(value2);

       push(value1);

       push(value3);

       push(value2);

       push(value1);

       break;

     }

   case Bytecodes::_dup2_x2:

     {

       ciType* value1 = pop_value();

       ciType* value2 = pop_value();

       ciType* value3 = pop_value();

       ciType* value4 = pop_value();

       push(value2);

       push(value1);

       push(value4);

       push(value3);

       push(value2);

       push(value1);

       break;

     }

   case Bytecodes::_f2d:

     {

       pop_float();

       push_double();

       break;

     }

   case Bytecodes::_f2i:

     {

       pop_float();

       push_int();

       break;

     }

   case Bytecodes::_f2l:

     {

       pop_float();

       push_long();

       break;

     }

   case Bytecodes::_fadd:

   case Bytecodes::_fdiv:

   case Bytecodes::_fmul:

   case Bytecodes::_frem:

   case Bytecodes::_fsub:

     {

       pop_float();

       pop_float();

       push_float();

       break;

     }

   case Bytecodes::_faload:

     {

       pop_int();

       ciTypeArrayKlass* array_klass = pop_typeArray();

       // Put assert here.

       push_float();

       break;

     }

   case Bytecodes::_fastore:

     {

       pop_float();

       pop_int();

       ciTypeArrayKlass* array_klass = pop_typeArray();

       // Put assert here.

       break;

     }

   case Bytecodes::_fcmpg:

   case Bytecodes::_fcmpl:

     {

       pop_float();

       pop_float();

       push_int();

       break;

     }

   case Bytecodes::_fconst_0:

   case Bytecodes::_fconst_1:

   case Bytecodes::_fconst_2:

     {

       push_float();

       break;

     }

   case Bytecodes::_fload:   load_local_float(str->get_index());     break;

   case Bytecodes::_fload_0: load_local_float(0);                    break;

   case Bytecodes::_fload_1: load_local_float(1);                    break;

   case Bytecodes::_fload_2: load_local_float(2);                    break;

   case Bytecodes::_fload_3: load_local_float(3);                    break;

   case Bytecodes::_fneg:

     {

       pop_float();

       push_float();

       break;

     }

   case Bytecodes::_freturn:

     {

       pop_float();

       break;

     }

   case Bytecodes::_fstore:    store_local_float(str->get_index());   break;

   case Bytecodes::_fstore_0:  store_local_float(0);                  break;

   case Bytecodes::_fstore_1:  store_local_float(1);                  break;

   case Bytecodes::_fstore_2:  store_local_float(2);                  break;

   case Bytecodes::_fstore_3:  store_local_float(3);                  break;

   case Bytecodes::_getfield:  do_getfield(str);                      break;

   case Bytecodes::_getstatic: do_getstatic(str);                     break;

   case Bytecodes::_goto:

   case Bytecodes::_goto_w:

   case Bytecodes::_nop:

   case Bytecodes::_return:

     {

       // do nothing.

       break;

     }

   case Bytecodes::_i2b:

   case Bytecodes::_i2c:

   case Bytecodes::_i2s:

   case Bytecodes::_ineg:

     {

       pop_int();

       push_int();

       break;

     }

   case Bytecodes::_i2d:

     {

       pop_int();

       push_double();

       break;

     }

   case Bytecodes::_i2f:

     {

       pop_int();

       push_float();

       break;

     }

   case Bytecodes::_i2l:

     {

       pop_int();

       push_long();

       break;

     }

   case Bytecodes::_iadd:

   case Bytecodes::_iand:

   case Bytecodes::_idiv:

   case Bytecodes::_imul:

   case Bytecodes::_ior:

   case Bytecodes::_irem:

   case Bytecodes::_ishl:

   case Bytecodes::_ishr:

   case Bytecodes::_isub:

   case Bytecodes::_iushr:

   case Bytecodes::_ixor:

     {

       pop_int();

       pop_int();

       push_int();

       break;

     }

   case Bytecodes::_if_acmpeq:

   case Bytecodes::_if_acmpne:

     {

       pop_object();

       pop_object();

       break;

     }

   case Bytecodes::_if_icmpeq:

   case Bytecodes::_if_icmpge:

   case Bytecodes::_if_icmpgt:

   case Bytecodes::_if_icmple:

   case Bytecodes::_if_icmplt:

   case Bytecodes::_if_icmpne:

     {

       pop_int();

       pop_int();

       break;

     }

   case Bytecodes::_ifeq:

   case Bytecodes::_ifle:

   case Bytecodes::_iflt:

   case Bytecodes::_ifge:

   case Bytecodes::_ifgt:

   case Bytecodes::_ifne:

   case Bytecodes::_ireturn:

   case Bytecodes::_lookupswitch:

   case Bytecodes::_tableswitch:

     {

       pop_int();

       break;

     }

   case Bytecodes::_iinc:

     {

       int lnum = str->get_index();

       check_int(local(lnum));

       store_to_local(lnum);

       break;

     }

   case Bytecodes::_iload:   load_local_int(str->get_index()); break;

   case Bytecodes::_iload_0: load_local_int(0);                      break;

   case Bytecodes::_iload_1: load_local_int(1);                      break;

   case Bytecodes::_iload_2: load_local_int(2);                      break;

   case Bytecodes::_iload_3: load_local_int(3);                      break;

   case Bytecodes::_instanceof:

     {

       // Check for uncommon trap:

       do_checkcast(str);

       pop_object();

       push_int();

       break;

     }

   case Bytecodes::_invokeinterface: do_invoke(str, true);           break;

   case Bytecodes::_invokespecial:   do_invoke(str, true);           break;

   case Bytecodes::_invokestatic:    do_invoke(str, false);          break;

   case Bytecodes::_invokevirtual:   do_invoke(str, true);           break;

   case Bytecodes::_istore:   store_local_int(str->get_index());     break;

   case Bytecodes::_istore_0: store_local_int(0);                    break;

   case Bytecodes::_istore_1: store_local_int(1);                    break;

   case Bytecodes::_istore_2: store_local_int(2);                    break;

   case Bytecodes::_istore_3: store_local_int(3);                    break;

   case Bytecodes::_jsr:

   case Bytecodes::_jsr_w: do_jsr(str);                              break;

   case Bytecodes::_l2d:

     {

       pop_long();

       push_double();

       break;

     }

   case Bytecodes::_l2f:

     {

       pop_long();

       push_float();

       break;

     }

   case Bytecodes::_l2i:

     {

       pop_long();

       push_int();

       break;

     }

   case Bytecodes::_ladd:

   case Bytecodes::_land:

   case Bytecodes::_ldiv:

   case Bytecodes::_lmul:

   case Bytecodes::_lor:

   case Bytecodes::_lrem:

   case Bytecodes::_lsub:

   case Bytecodes::_lxor:

     {

       pop_long();

       pop_long();

       push_long();

       break;

     }

   case Bytecodes::_laload:

     {

       pop_int();

       ciTypeArrayKlass* array_klass = pop_typeArray();

       // Put assert here for right type?

       push_long();

       break;

     }

   case Bytecodes::_lastore:

     {

       pop_long();

       pop_int();

       pop_typeArray();

       // assert here?

       break;

     }

   case Bytecodes::_lcmp:

     {

       pop_long();

       pop_long();

       push_int();

       break;

     }

   case Bytecodes::_lconst_0:

   case Bytecodes::_lconst_1:

     {

       push_long();

       break;

     }

   case Bytecodes::_ldc:

   case Bytecodes::_ldc_w:

   case Bytecodes::_ldc2_w:

     {

       do_ldc(str);

       break;

     }

   case Bytecodes::_lload:   load_local_long(str->get_index());      break;

   case Bytecodes::_lload_0: load_local_long(0);                     break;

   case Bytecodes::_lload_1: load_local_long(1);                     break;

   case Bytecodes::_lload_2: load_local_long(2);                     break;

   case Bytecodes::_lload_3: load_local_long(3);                     break;

   case Bytecodes::_lneg:

     {

       pop_long();

       push_long();

       break;

     }

   case Bytecodes::_lreturn:

     {

       pop_long();

       break;

     }

   case Bytecodes::_lshl:

   case Bytecodes::_lshr:

   case Bytecodes::_lushr:

     {

       pop_int();

       pop_long();

       push_long();

       break;

     }

   case Bytecodes::_lstore:   store_local_long(str->get_index());    break;

   case Bytecodes::_lstore_0: store_local_long(0);                   break;

   case Bytecodes::_lstore_1: store_local_long(1);                   break;

   case Bytecodes::_lstore_2: store_local_long(2);                   break;

   case Bytecodes::_lstore_3: store_local_long(3);                   break;

   case Bytecodes::_multianewarray: do_multianewarray(str);          break;

   case Bytecodes::_new:      do_new(str);                           break;

   case Bytecodes::_newarray: do_newarray(str);                      break;

   case Bytecodes::_pop:

     {

       pop();

       break;

     }

   case Bytecodes::_pop2:

     {

       pop();

       pop();

       break;

     }

   case Bytecodes::_putfield:       do_putfield(str);                 break;

   case Bytecodes::_putstatic:      do_putstatic(str);                break;

   case Bytecodes::_ret: do_ret(str);                                 break;

   case Bytecodes::_swap:

     {

       ciType* value1 = pop_value();

       ciType* value2 = pop_value();

       push(value1);

       push(value2);

       break;

     }

   case Bytecodes::_wide:

   default:

     {

       // The iterator should skip this.

       ShouldNotReachHere();

       break;

     }

   }

   if (CITraceTypeFlow) {

     print_on(tty);

   }

   return (_trap_bci != -1);

 }

 #ifndef PRODUCT

 // ------------------------------------------------------------------

 // ciTypeFlow::StateVector::print_cell_on

 void ciTypeFlow::StateVector::print_cell_on(outputStream* st, Cell c) const {

   ciType* type = type_at(c);

   if (type == top_type()) {

     st->print("top");

   } else if (type == bottom_type()) {

     st->print("bottom");

   } else if (type == null_type()) {

     st->print("null");

   } else if (type == long2_type()) {

     st->print("long2");

   } else if (type == double2_type()) {

     st->print("double2");

   } else if (is_int(type)) {

     st->print("int");

   } else if (is_long(type)) {

     st->print("long");

   } else if (is_float(type)) {

     st->print("float");

   } else if (is_double(type)) {

     st->print("double");

   } else if (type->is_return_address()) {

     st->print("address(%d)", type->as_return_address()->bci());

   } else {

     if (type->is_klass()) {

       type->as_klass()->name()->print_symbol_on(st);

     } else {

       st->print("UNEXPECTED TYPE");

       type->print();

     }

   }

 }

 // ------------------------------------------------------------------

 // ciTypeFlow::StateVector::print_on

 void ciTypeFlow::StateVector::print_on(outputStream* st) const {

   int num_locals   = _outer->max_locals();

   int num_stack    = stack_size();

   int num_monitors = monitor_count();

   st->print_cr("  State : locals %d, stack %d, monitors %d", num_locals, num_stack, num_monitors);

   if (num_stack >= 0) {

     int i;

     for (i = 0; i < num_locals; i++) {

       st->print("    local %2d : ", i);

       print_cell_on(st, local(i));

       st->cr();

     }

     for (i = 0; i < num_stack; i++) {

       st->print("    stack %2d : ", i);

       print_cell_on(st, stack(i));

       st->cr();

     }

   }

 }

 #endif

 // ------------------------------------------------------------------

 // ciTypeFlow::SuccIter::next

 //

 void ciTypeFlow::SuccIter::next() {

   int succ_ct = _pred->successors()->length();

   int next = _index + 1;

   if (next < succ_ct) {

     _index = next;

     _succ = _pred->successors()->at(next);

     return;

   }

   for (int i = next - succ_ct; i < _pred->exceptions()->length(); i++) {

     // Do not compile any code for unloaded exception types.

     // Following compiler passes are responsible for doing this also.

     ciInstanceKlass* exception_klass = _pred->exc_klasses()->at(i);

     if (exception_klass->is_loaded()) {

       _index = next;

       _succ = _pred->exceptions()->at(i);

       return;

     }

     next++;

   }

   _index = -1;

   _succ = NULL;

 }

 // ------------------------------------------------------------------

 // ciTypeFlow::SuccIter::set_succ

 //

 void ciTypeFlow::SuccIter::set_succ(Block* succ) {

   int succ_ct = _pred->successors()->length();

   if (_index < succ_ct) {

     _pred->successors()->at_put(_index, succ);

   } else {

     int idx = _index - succ_ct;

     _pred->exceptions()->at_put(idx, succ);

   }

 }

 // ciTypeFlow::Block

 //

 // A basic block.

 // ------------------------------------------------------------------

 // ciTypeFlow::Block::Block

 ciTypeFlow::Block::Block(ciTypeFlow* outer,

                          ciBlock *ciblk,

                          ciTypeFlow::JsrSet* jsrs) {

   _ciblock = ciblk;

   _exceptions = NULL;

   _exc_klasses = NULL;

   _successors = NULL;

   _state = new (outer->arena()) StateVector(outer);

   JsrSet* new_jsrs =

     new (outer->arena()) JsrSet(outer->arena(), jsrs->size());

   jsrs->copy_into(new_jsrs);

   _jsrs = new_jsrs;

   _next = NULL;

   _on_work_list = false;

   _backedge_copy = false;

   _exception_entry = false;

   _trap_bci = -1;

   _trap_index = 0;

   df_init();

   if (CITraceTypeFlow) {

     tty->print_cr(">> Created new block");

     print_on(tty);

   }

   assert(this->outer() == outer, "outer link set up");

   assert(!outer->have_block_count(), "must not have mapped blocks yet");

 }

 // ------------------------------------------------------------------

 // ciTypeFlow::Block::df_init

 void ciTypeFlow::Block::df_init() {

   _pre_order = -1; assert(!has_pre_order(), "");

   _post_order = -1; assert(!has_post_order(), "");

   _loop = NULL;

   _irreducible_entry = false;

   _rpo_next = NULL;

 }

 // ------------------------------------------------------------------

 // ciTypeFlow::Block::successors

 //

 // Get the successors for this Block.

 GrowableArray<ciTypeFlow::Block*>*

 ciTypeFlow::Block::successors(ciBytecodeStream* str,

                               ciTypeFlow::StateVector* state,

                               ciTypeFlow::JsrSet* jsrs) {

   if (_successors == NULL) {

     if (CITraceTypeFlow) {

       tty->print(">> Computing successors for block ");

       print_value_on(tty);

       tty->cr();

     }

     ciTypeFlow* analyzer = outer();

     Arena* arena = analyzer->arena();

     Block* block = NULL;

     bool has_successor = !has_trap() &&

                          (control() != ciBlock::fall_through_bci || limit() < analyzer->code_size());

     if (!has_successor) {

       _successors =

         new (arena) GrowableArray<Block*>(arena, 1, 0, NULL);

       // No successors

     } else if (control() == ciBlock::fall_through_bci) {

       assert(str->cur_bci() == limit(), "bad block end");

       // This block simply falls through to the next.

       _successors =

         new (arena) GrowableArray<Block*>(arena, 1, 0, NULL);

       Block* block = analyzer->block_at(limit(), _jsrs);

       assert(_successors->length() == FALL_THROUGH, "");

       _successors->append(block);

     } else {

       int current_bci = str->cur_bci();

       int next_bci = str->next_bci();

       int branch_bci = -1;

       Block* target = NULL;

       assert(str->next_bci() == limit(), "bad block end");

       // This block is not a simple fall-though.  Interpret

       // the current bytecode to find our successors.

       switch (str->cur_bc()) {

       case Bytecodes::_ifeq:         case Bytecodes::_ifne:

       case Bytecodes::_iflt:         case Bytecodes::_ifge:

       case Bytecodes::_ifgt:         case Bytecodes::_ifle:

       case Bytecodes::_if_icmpeq:    case Bytecodes::_if_icmpne:

       case Bytecodes::_if_icmplt:    case Bytecodes::_if_icmpge:

       case Bytecodes::_if_icmpgt:    case Bytecodes::_if_icmple:

       case Bytecodes::_if_acmpeq:    case Bytecodes::_if_acmpne:

       case Bytecodes::_ifnull:       case Bytecodes::_ifnonnull:

         // Our successors are the branch target and the next bci.

         branch_bci = str->get_dest();

         _successors =

           new (arena) GrowableArray<Block*>(arena, 2, 0, NULL);

         assert(_successors->length() == IF_NOT_TAKEN, "");

         _successors->append(analyzer->block_at(next_bci, jsrs));

         assert(_successors->length() == IF_TAKEN, "");

         _successors->append(analyzer->block_at(branch_bci, jsrs));

         break;

       case Bytecodes::_goto:

         branch_bci = str->get_dest();

         _successors =

           new (arena) GrowableArray<Block*>(arena, 1, 0, NULL);

         assert(_successors->length() == GOTO_TARGET, "");

         _successors->append(analyzer->block_at(branch_bci, jsrs));

         break;

       case Bytecodes::_jsr:

         branch_bci = str->get_dest();

         _successors =

           new (arena) GrowableArray<Block*>(arena, 1, 0, NULL);

         assert(_successors->length() == GOTO_TARGET, "");

         _successors->append(analyzer->block_at(branch_bci, jsrs));

         break;

       case Bytecodes::_goto_w:

       case Bytecodes::_jsr_w:

         _successors =

           new (arena) GrowableArray<Block*>(arena, 1, 0, NULL);

         assert(_successors->length() == GOTO_TARGET, "");

         _successors->append(analyzer->block_at(str->get_far_dest(), jsrs));

         break;

       case Bytecodes::_tableswitch:  {

         Bytecode_tableswitch *tableswitch =

           Bytecode_tableswitch_at(str->cur_bcp());

         int len = tableswitch->length();

         _successors =

           new (arena) GrowableArray<Block*>(arena, len+1, 0, NULL);

         int bci = current_bci + tableswitch->default_offset();

         Block* block = analyzer->block_at(bci, jsrs);

         assert(_successors->length() == SWITCH_DEFAULT, "");

         _successors->append(block);

         while (--len >= 0) {

           int bci = current_bci + tableswitch->dest_offset_at(len);

           block = analyzer->block_at(bci, jsrs);

           assert(_successors->length() >= SWITCH_CASES, "");

           _successors->append_if_missing(block);

         }

         break;

       }

       case Bytecodes::_lookupswitch: {

         Bytecode_lookupswitch *lookupswitch =

           Bytecode_lookupswitch_at(str->cur_bcp());

         int npairs = lookupswitch->number_of_pairs();

         _successors =

           new (arena) GrowableArray<Block*>(arena, npairs+1, 0, NULL);

         int bci = current_bci + lookupswitch->default_offset();

         Block* block = analyzer->block_at(bci, jsrs);

         assert(_successors->length() == SWITCH_DEFAULT, "");

         _successors->append(block);

         while(--npairs >= 0) {

           LookupswitchPair *pair = lookupswitch->pair_at(npairs);

           int bci = current_bci + pair->offset();

           Block* block = analyzer->block_at(bci, jsrs);

           assert(_successors->length() >= SWITCH_CASES, "");

           _successors->append_if_missing(block);

         }

         break;

       }

       case Bytecodes::_athrow:     case Bytecodes::_ireturn:

       case Bytecodes::_lreturn:    case Bytecodes::_freturn:

       case Bytecodes::_dreturn:    case Bytecodes::_areturn:

       case Bytecodes::_return:

         _successors =

           new (arena) GrowableArray<Block*>(arena, 1, 0, NULL);

         // No successors

         break;

       case Bytecodes::_ret: {

         _successors =

           new (arena) GrowableArray<Block*>(arena, 1, 0, NULL);

         Cell local = state->local(str->get_index());

         ciType* return_address = state->type_at(local);

         assert(return_address->is_return_address(), "verify: wrong type");

         int bci = return_address->as_return_address()->bci();

         assert(_successors->length() == GOTO_TARGET, "");

         _successors->append(analyzer->block_at(bci, jsrs));

         break;

       }

       case Bytecodes::_wide:

       default:

         ShouldNotReachHere();

         break;

       }

     }

   }

   return _successors;

 }

 // ------------------------------------------------------------------

 // ciTypeFlow::Block:compute_exceptions

 //

 // Compute the exceptional successors and types for this Block.

 void ciTypeFlow::Block::compute_exceptions() {

   assert(_exceptions == NULL && _exc_klasses == NULL, "repeat");

   if (CITraceTypeFlow) {

     tty->print(">> Computing exceptions for block ");

     print_value_on(tty);

     tty->cr();

   }

   ciTypeFlow* analyzer = outer();

   Arena* arena = analyzer->arena();

   // Any bci in the block will do.

   ciExceptionHandlerStream str(analyzer->method(), start());

   // Allocate our growable arrays.

   int exc_count = str.count();

   _exceptions = new (arena) GrowableArray<Block*>(arena, exc_count, 0, NULL);

   _exc_klasses = new (arena) GrowableArray<ciInstanceKlass*>(arena, exc_count,

                                                              0, NULL);

   for ( ; !str.is_done(); str.next()) {

     ciExceptionHandler* handler = str.handler();

     int bci = handler->handler_bci();

     ciInstanceKlass* klass = NULL;

     if (bci == -1) {

       // There is no catch all.  It is possible to exit the method.

       break;

     }

     if (handler->is_catch_all()) {

       klass = analyzer->env()->Throwable_klass();

     } else {

       klass = handler->catch_klass();

     }

     _exceptions->append(analyzer->block_at(bci, _jsrs));

     _exc_klasses->append(klass);

   }

 }

 // ------------------------------------------------------------------

 // ciTypeFlow::Block::set_backedge_copy

 // Use this only to make a pre-existing public block into a backedge copy.

 void ciTypeFlow::Block::set_backedge_copy(bool z) {

   assert(z || (z == is_backedge_copy()), "cannot make a backedge copy public");

   _backedge_copy = z;

 }

 // ------------------------------------------------------------------

 // ciTypeFlow::Block::is_clonable_exit

 //

 // At most 2 normal successors, one of which continues looping,

 // and all exceptional successors must exit.

 bool ciTypeFlow::Block::is_clonable_exit(ciTypeFlow::Loop* lp) {

   int normal_cnt  = 0;

   int in_loop_cnt = 0;

   for (SuccIter iter(this); !iter.done(); iter.next()) {

     Block* succ = iter.succ();

     if (iter.is_normal_ctrl()) {

       if (++normal_cnt > 2) return false;

       if (lp->contains(succ->loop())) {

         if (++in_loop_cnt > 1) return false;

       }

     } else {

       if (lp->contains(succ->loop())) return false;

     }

   }

   return in_loop_cnt == 1;

 }

 // ------------------------------------------------------------------

 // ciTypeFlow::Block::looping_succ

 //

 ciTypeFlow::Block* ciTypeFlow::Block::looping_succ(ciTypeFlow::Loop* lp) {

   assert(successors()->length() <= 2, "at most 2 normal successors");

   for (SuccIter iter(this); !iter.done(); iter.next()) {

     Block* succ = iter.succ();

     if (lp->contains(succ->loop())) {

       return succ;

     }

   }

   return NULL;

 }

 #ifndef PRODUCT

 // ------------------------------------------------------------------

 // ciTypeFlow::Block::print_value_on

 void ciTypeFlow::Block::print_value_on(outputStream* st) const {

   if (has_pre_order()) st->print("#%-2d ", pre_order());

   if (has_rpo())       st->print("rpo#%-2d ", rpo());

   st->print("[%d - %d)", start(), limit());

   if (is_loop_head()) st->print(" lphd");

   if (is_irreducible_entry()) st->print(" irred");

   if (_jsrs->size() > 0) { st->print("/");  _jsrs->print_on(st); }

   if (is_backedge_copy())  st->print("/backedge_copy");

 }

 // ------------------------------------------------------------------

 // ciTypeFlow::Block::print_on

 void ciTypeFlow::Block::print_on(outputStream* st) const {

   if ((Verbose || WizardMode)) {

     outer()->method()->print_codes_on(start(), limit(), st);

   }

   st->print_cr("  ====================================================  ");

   st->print ("  ");

   print_value_on(st);

   st->print(" Stored locals: "); def_locals()->print_on(st, outer()->method()->max_locals()); tty->cr();

   if (loop() && loop()->parent() != NULL) {

     st->print(" loops:");

     Loop* lp = loop();

     do {

       st->print(" %d<-%d", lp->head()->pre_order(),lp->tail()->pre_order());

       if (lp->is_irreducible()) st->print("(ir)");

       lp = lp->parent();

     } while (lp->parent() != NULL);

   }

   st->cr();

   _state->print_on(st);

   if (_successors == NULL) {

     st->print_cr("  No successor information");

   } else {

     int num_successors = _successors->length();

     st->print_cr("  Successors : %d", num_successors);

     for (int i = 0; i < num_successors; i++) {

       Block* successor = _successors->at(i);

       st->print("    ");

       successor->print_value_on(st);

       st->cr();

     }

   }

   if (_exceptions == NULL) {

     st->print_cr("  No exception information");

   } else {

     int num_exceptions = _exceptions->length();

     st->print_cr("  Exceptions : %d", num_exceptions);

     for (int i = 0; i < num_exceptions; i++) {

       Block* exc_succ = _exceptions->at(i);

       ciInstanceKlass* exc_klass = _exc_klasses->at(i);

       st->print("    ");

       exc_succ->print_value_on(st);

       st->print(" -- ");

       exc_klass->name()->print_symbol_on(st);

       st->cr();

     }

   }

   if (has_trap()) {

     st->print_cr("  Traps on %d with trap index %d", trap_bci(), trap_index());

   }

   st->print_cr("  ====================================================  ");

 }

 #endif

 #ifndef PRODUCT

 // ------------------------------------------------------------------

 // ciTypeFlow::LocalSet::print_on

 void ciTypeFlow::LocalSet::print_on(outputStream* st, int limit) const {

   st->print("{");

   for (int i = 0; i < max; i++) {

     if (test(i)) st->print(" %d", i);

   }

   if (limit > max) {

     st->print(" %d..%d ", max, limit);

   }

   st->print(" }");

 }

 #endif

 // ciTypeFlow

 //

 // This is a pass over the bytecodes which computes the following:

 //   basic block structure

 //   interpreter type-states (a la the verifier)

 // ------------------------------------------------------------------

 // ciTypeFlow::ciTypeFlow

 ciTypeFlow::ciTypeFlow(ciEnv* env, ciMethod* method, int osr_bci) {

   _env = env;

   _method = method;

   _methodBlocks = method->get_method_blocks();

   _max_locals = method->max_locals();

   _max_stack = method->max_stack();

   _code_size = method->code_size();

   _has_irreducible_entry = false;

   _osr_bci = osr_bci;

   _failure_reason = NULL;

   assert(start_bci() >= 0 && start_bci() < code_size() , "correct osr_bci argument");

   _work_list = NULL;

   _ciblock_count = _methodBlocks->num_blocks();

   _idx_to_blocklist = NEW_ARENA_ARRAY(arena(), GrowableArray<Block*>*, _ciblock_count);

   for (int i = 0; i < _ciblock_count; i++) {

     _idx_to_blocklist[i] = NULL;

   }

   _block_map = NULL;  // until all blocks are seen

   _jsr_count = 0;

   _jsr_records = NULL;

 }

 // ------------------------------------------------------------------

 // ciTypeFlow::work_list_next

 //

 // Get the next basic block from our work list.

 ciTypeFlow::Block* ciTypeFlow::work_list_next() {

   assert(!work_list_empty(), "work list must not be empty");

   Block* next_block = _work_list;

   _work_list = next_block->next();

   next_block->set_next(NULL);

   next_block->set_on_work_list(false);

   return next_block;

 }

 // ------------------------------------------------------------------

 // ciTypeFlow::add_to_work_list

 //

 // Add a basic block to our work list.

 // List is sorted by decreasing postorder sort (same as increasing RPO)

 void ciTypeFlow::add_to_work_list(ciTypeFlow::Block* block) {

   assert(!block->is_on_work_list(), "must not already be on work list");

   if (CITraceTypeFlow) {

     tty->print(">> Adding block ");

     block->print_value_on(tty);

     tty->print_cr(" to the work list : ");

   }

   block->set_on_work_list(true);

   // decreasing post order sort

   Block* prev = NULL;

   Block* current = _work_list;

   int po = block->post_order();

   while (current != NULL) {

     if (!current->has_post_order() || po > current->post_order())

       break;

     prev = current;

     current = current->next();

   }

   if (prev == NULL) {

     block->set_next(_work_list);

     _work_list = block;

   } else {

     block->set_next(current);

     prev->set_next(block);

   }

   if (CITraceTypeFlow) {

     tty->cr();

   }

 }

 // ------------------------------------------------------------------

 // ciTypeFlow::block_at

 //

 // Return the block beginning at bci which has a JsrSet compatible

 // with jsrs.

 ciTypeFlow::Block* ciTypeFlow::block_at(int bci, ciTypeFlow::JsrSet* jsrs, CreateOption option) {

   // First find the right ciBlock.

   if (CITraceTypeFlow) {

     tty->print(">> Requesting block for %d/", bci);

     jsrs->print_on(tty);

     tty->cr();

   }

   ciBlock* ciblk = _methodBlocks->block_containing(bci);

   assert(ciblk->start_bci() == bci, "bad ciBlock boundaries");

   Block* block = get_block_for(ciblk->index(), jsrs, option);

   assert(block == NULL? (option == no_create): block->is_backedge_copy() == (option == create_backedge_copy), "create option consistent with result");

   if (CITraceTypeFlow) {

     if (block != NULL) {

       tty->print(">> Found block ");

       block->print_value_on(tty);

       tty->cr();

     } else {

       tty->print_cr(">> No such block.");

     }

   }

   return block;

 }

 // ------------------------------------------------------------------

 // ciTypeFlow::make_jsr_record

 //

 // Make a JsrRecord for a given (entry, return) pair, if such a record

 // does not already exist.

 ciTypeFlow::JsrRecord* ciTypeFlow::make_jsr_record(int entry_address,

                                                    int return_address) {

   if (_jsr_records == NULL) {

     _jsr_records = new (arena()) GrowableArray<JsrRecord*>(arena(),

                                                            _jsr_count,

                                                            0,

                                                            NULL);

   }

   JsrRecord* record = NULL;

   int len = _jsr_records->length();

   for (int i = 0; i < len; i++) {

     JsrRecord* record = _jsr_records->at(i);

     if (record->entry_address() == entry_address &&

         record->return_address() == return_address) {

       return record;

     }

   }

   record = new (arena()) JsrRecord(entry_address, return_address);

   _jsr_records->append(record);

   return record;

 }

 // ------------------------------------------------------------------

 // ciTypeFlow::flow_exceptions

 //

 // Merge the current state into all exceptional successors at the

 // current point in the code.

 void ciTypeFlow::flow_exceptions(GrowableArray<ciTypeFlow::Block*>* exceptions,

                                  GrowableArray<ciInstanceKlass*>* exc_klasses,

                                  ciTypeFlow::StateVector* state) {

   int len = exceptions->length();

   assert(exc_klasses->length() == len, "must have same length");

   for (int i = 0; i < len; i++) {

     Block* block = exceptions->at(i);

     ciInstanceKlass* exception_klass = exc_klasses->at(i);

     if (!exception_klass->is_loaded()) {

       // Do not compile any code for unloaded exception types.

       // Following compiler passes are responsible for doing this also.

       continue;

     }

     if (block->meet_exception(exception_klass, state)) {

       // Block was modified and has PO.  Add it to the work list.

       if (block->has_post_order() &&

           !block->is_on_work_list()) {

         add_to_work_list(block);

       }

     }

   }

 }

 // ------------------------------------------------------------------

 // ciTypeFlow::flow_successors

 //

 // Merge the current state into all successors at the current point

 // in the code.

 void ciTypeFlow::flow_successors(GrowableArray<ciTypeFlow::Block*>* successors,

                                  ciTypeFlow::StateVector* state) {

   int len = successors->length();

   for (int i = 0; i < len; i++) {

     Block* block = successors->at(i);

     if (block->meet(state)) {

       // Block was modified and has PO.  Add it to the work list.

       if (block->has_post_order() &&

           !block->is_on_work_list()) {

         add_to_work_list(block);

       }

     }

   }

 }

 // ------------------------------------------------------------------

 // ciTypeFlow::can_trap

 //

 // Tells if a given instruction is able to generate an exception edge.

 bool ciTypeFlow::can_trap(ciBytecodeStream& str) {

   // Cf. GenerateOopMap::do_exception_edge.

   if (!Bytecodes::can_trap(str.cur_bc()))  return false;

   switch (str.cur_bc()) {

     case Bytecodes::_ldc:

     case Bytecodes::_ldc_w:

     case Bytecodes::_ldc2_w:

     case Bytecodes::_aload_0:

       // These bytecodes can trap for rewriting.  We need to assume that

       // they do not throw exceptions to make the monitor analysis work.

       return false;

     case Bytecodes::_ireturn:

     case Bytecodes::_lreturn:

     case Bytecodes::_freturn:

     case Bytecodes::_dreturn:

     case Bytecodes::_areturn:

     case Bytecodes::_return:

       // We can assume the monitor stack is empty in this analysis.

       return false;

     case Bytecodes::_monitorexit:

       // We can assume monitors are matched in this analysis.

       return false;

   }

   return true;

 }

 // ------------------------------------------------------------------

 // ciTypeFlow::clone_loop_heads

 //

 // Clone the loop heads

 bool ciTypeFlow::clone_loop_heads(Loop* lp, StateVector* temp_vector, JsrSet* temp_set) {

   bool rslt = false;

   for (PreorderLoops iter(loop_tree_root()); !iter.done(); iter.next()) {

     lp = iter.current();

     Block* head = lp->head();

     if (lp == loop_tree_root() ||

         lp->is_irreducible() ||

         !head->is_clonable_exit(lp))

       continue;

     // check not already cloned

     if (head->backedge_copy_count() != 0)

       continue;

     // check _no_ shared head below us

     Loop* ch;

     for (ch = lp->child(); ch != NULL && ch->head() != head; ch = ch->sibling());

     if (ch != NULL)

       continue;

     // Clone head

     Block* new_head = head->looping_succ(lp);

     Block* clone = clone_loop_head(lp, temp_vector, temp_set);

     // Update lp's info

     clone->set_loop(lp);

     lp->set_head(new_head);

     lp->set_tail(clone);

     // And move original head into outer loop

     head->set_loop(lp->parent());

     rslt = true;

   }

   return rslt;

 }

 // ------------------------------------------------------------------

 // ciTypeFlow::clone_loop_head

 //

 // Clone lp's head and replace tail's successors with clone.

 //

 //  |

 //  v

 // head <-> body

 //  |

 //  v

 // exit

 //

 // new_head

 //

 //  |

 //  v

 // head ----------\

 //  |             |

 //  |             v

 //  |  clone <-> body

 //  |    |

 //  | /--/

 //  | |

 //  v v

 // exit

 //

 ciTypeFlow::Block* ciTypeFlow::clone_loop_head(Loop* lp, StateVector* temp_vector, JsrSet* temp_set) {

   Block* head = lp->head();

   Block* tail = lp->tail();

   if (CITraceTypeFlow) {

     tty->print(">> Requesting clone of loop head "); head->print_value_on(tty);

     tty->print("  for predecessor ");                tail->print_value_on(tty);

     tty->cr();

   }

   Block* clone = block_at(head->start(), head->jsrs(), create_backedge_copy);

   assert(clone->backedge_copy_count() == 1, "one backedge copy for all back edges");

   assert(!clone->has_pre_order(), "just created");

   clone->set_next_pre_order();

   // Insert clone after (orig) tail in reverse post order

   clone->set_rpo_next(tail->rpo_next());

   tail->set_rpo_next(clone);

   // tail->head becomes tail->clone

   for (SuccIter iter(tail); !iter.done(); iter.next()) {

     if (iter.succ() == head) {

       iter.set_succ(clone);

       break;

     }

   }

   flow_block(tail, temp_vector, temp_set);

   if (head == tail) {

     // For self-loops, clone->head becomes clone->clone

     flow_block(clone, temp_vector, temp_set);

     for (SuccIter iter(clone); !iter.done(); iter.next()) {

       if (iter.succ() == head) {

         iter.set_succ(clone);

         break;

       }

     }

   }

   flow_block(clone, temp_vector, temp_set);

   return clone;

 }

 // ------------------------------------------------------------------

 // ciTypeFlow::flow_block

 //

 // Interpret the effects of the bytecodes on the incoming state

 // vector of a basic block.  Push the changed state to succeeding

 // basic blocks.

 void ciTypeFlow::flow_block(ciTypeFlow::Block* block,

                             ciTypeFlow::StateVector* state,

                             ciTypeFlow::JsrSet* jsrs) {

   if (CITraceTypeFlow) {

     tty->print("\n>> ANALYZING BLOCK : ");

     tty->cr();

     block->print_on(tty);

   }

   assert(block->has_pre_order(), "pre-order is assigned before 1st flow");

   int start = block->start();

   int limit = block->limit();

   int control = block->control();

   if (control != ciBlock::fall_through_bci) {

     limit = control;

   }

   // Grab the state from the current block.

   block->copy_state_into(state);

   state->def_locals()->clear();

   GrowableArray<Block*>*           exceptions = block->exceptions();

   GrowableArray<ciInstanceKlass*>* exc_klasses = block->exc_klasses();

   bool has_exceptions = exceptions->length() > 0;

   bool exceptions_used = false;

   ciBytecodeStream str(method());

   str.reset_to_bci(start);

   Bytecodes::Code code;

   while ((code = str.next()) != ciBytecodeStream::EOBC() &&

          str.cur_bci() < limit) {

     // Check for exceptional control flow from this point.

     if (has_exceptions && can_trap(str)) {

       flow_exceptions(exceptions, exc_klasses, state);

       exceptions_used = true;

     }

     // Apply the effects of the current bytecode to our state.

     bool res = state->apply_one_bytecode(&str);

     // Watch for bailouts.

     if (failing())  return;

     if (res) {

       // We have encountered a trap.  Record it in this block.

       block->set_trap(state->trap_bci(), state->trap_index());

       if (CITraceTypeFlow) {

         tty->print_cr(">> Found trap");

         block->print_on(tty);

       }

       // Save set of locals defined in this block

       block->def_locals()->add(state->def_locals());

       // Record (no) successors.

       block->successors(&str, state, jsrs);

       assert(!has_exceptions || exceptions_used, "Not removing exceptions");

       // Discontinue interpretation of this Block.

       return;

     }

   }

   GrowableArray<Block*>* successors = NULL;

   if (control != ciBlock::fall_through_bci) {

     // Check for exceptional control flow from this point.

     if (has_exceptions && can_trap(str)) {

       flow_exceptions(exceptions, exc_klasses, state);

       exceptions_used = true;

     }

     // Fix the JsrSet to reflect effect of the bytecode.

     block->copy_jsrs_into(jsrs);

     jsrs->apply_control(this, &str, state);

     // Find successor edges based on old state and new JsrSet.

     successors = block->successors(&str, state, jsrs);

     // Apply the control changes to the state.

     state->apply_one_bytecode(&str);

   } else {

     // Fall through control

     successors = block->successors(&str, NULL, NULL);

   }

   // Save set of locals defined in this block

   block->def_locals()->add(state->def_locals());

   // Remove untaken exception paths

   if (!exceptions_used)

     exceptions->clear();

   // Pass our state to successors.

   flow_successors(successors, state);

 }

 // ------------------------------------------------------------------

 // ciTypeFlow::PostOrderLoops::next

 //

 // Advance to next loop tree using a postorder, left-to-right traversal.

 void ciTypeFlow::PostorderLoops::next() {

   assert(!done(), "must not be done.");

   if (_current->sibling() != NULL) {

     _current = _current->sibling();

     while (_current->child() != NULL) {

       _current = _current->child();

     }

   } else {

     _current = _current->parent();

   }

 }

 // ------------------------------------------------------------------

 // ciTypeFlow::PreOrderLoops::next

 //

 // Advance to next loop tree using a preorder, left-to-right traversal.

 void ciTypeFlow::PreorderLoops::next() {

   assert(!done(), "must not be done.");

   if (_current->child() != NULL) {

     _current = _current->child();

   } else if (_current->sibling() != NULL) {

     _current = _current->sibling();

   } else {

     while (_current != _root && _current->sibling() == NULL) {

       _current = _current->parent();

     }

     if (_current == _root) {

       _current = NULL;

       assert(done(), "must be done.");

     } else {

       assert(_current->sibling() != NULL, "must be more to do");

       _current = _current->sibling();

     }

   }

 }

 // ------------------------------------------------------------------

 // ciTypeFlow::Loop::sorted_merge

 //

 // Merge the branch lp into this branch, sorting on the loop head

 // pre_orders. Returns the leaf of the merged branch.

 // Child and sibling pointers will be setup later.

 // Sort is (looking from leaf towards the root)

 //  descending on primary key: loop head's pre_order, and

 //  ascending  on secondary key: loop tail's pre_order.

 ciTypeFlow::Loop* ciTypeFlow::Loop::sorted_merge(Loop* lp) {

   Loop* leaf = this;

   Loop* prev = NULL;

   Loop* current = leaf;

   while (lp != NULL) {

     int lp_pre_order = lp->head()->pre_order();

     // Find insertion point for "lp"

     while (current != NULL) {

       if (current == lp)

         return leaf; // Already in list

       if (current->head()->pre_order() < lp_pre_order)

         break;

       if (current->head()->pre_order() == lp_pre_order &&

           current->tail()->pre_order() > lp->tail()->pre_order()) {

         break;

       }

       prev = current;

       current = current->parent();

     }

     Loop* next_lp = lp->parent(); // Save future list of items to insert

     // Insert lp before current

     lp->set_parent(current);

     if (prev != NULL) {

       prev->set_parent(lp);

     } else {

       leaf = lp;

     }

     prev = lp;     // Inserted item is new prev[ious]

     lp = next_lp;  // Next item to insert

   }

   return leaf;

 }

 // ------------------------------------------------------------------

 // ciTypeFlow::build_loop_tree

 //

 // Incrementally build loop tree.

 void ciTypeFlow::build_loop_tree(Block* blk) {

   assert(!blk->is_post_visited(), "precondition");

   Loop* innermost = NULL; // merge of loop tree branches over all successors

   for (SuccIter iter(blk); !iter.done(); iter.next()) {

     Loop*  lp   = NULL;

     Block* succ = iter.succ();

     if (!succ->is_post_visited()) {

       // Found backedge since predecessor post visited, but successor is not

       assert(succ->pre_order() <= blk->pre_order(), "should be backedge");

       // Create a LoopNode to mark this loop.

       lp = new (arena()) Loop(succ, blk);

       if (succ->loop() == NULL)

         succ->set_loop(lp);

       // succ->loop will be updated to innermost loop on a later call, when blk==succ

     } else {  // Nested loop

       lp = succ->loop();

       // If succ is loop head, find outer loop.

       while (lp != NULL && lp->head() == succ) {

         lp = lp->parent();

       }

       if (lp == NULL) {

         // Infinite loop, it's parent is the root

         lp = loop_tree_root();

       }

     }

     // Check for irreducible loop.

     // Successor has already been visited. If the successor's loop head

     // has already been post-visited, then this is another entry into the loop.

     while (lp->head()->is_post_visited() && lp != loop_tree_root()) {

       _has_irreducible_entry = true;

       lp->set_irreducible(succ);

       if (!succ->is_on_work_list()) {

         // Assume irreducible entries need more data flow

         add_to_work_list(succ);

       }

       lp = lp->parent();

       assert(lp != NULL, "nested loop must have parent by now");

     }

     // Merge loop tree branch for all successors.

     innermost = innermost == NULL ? lp : innermost->sorted_merge(lp);

   } // end loop

   if (innermost == NULL) {

     assert(blk->successors()->length() == 0, "CFG exit");

     blk->set_loop(loop_tree_root());

   } else if (innermost->head() == blk) {

     // If loop header, complete the tree pointers

     if (blk->loop() != innermost) {

 #if ASSERT

       assert(blk->loop()->head() == innermost->head(), "same head");

       Loop* dl;

       for (dl = innermost; dl != NULL && dl != blk->loop(); dl = dl->parent());

       assert(dl == blk->loop(), "blk->loop() already in innermost list");

 #endif

       blk->set_loop(innermost);

     }

     innermost->def_locals()->add(blk->def_locals());

     Loop* l = innermost;

     Loop* p = l->parent();

     while (p && l->head() == blk) {

       l->set_sibling(p->child());  // Put self on parents 'next child'

       p->set_child(l);             // Make self the first child of parent

       p->def_locals()->add(l->def_locals());

       l = p;                       // Walk up the parent chain

       p = l->parent();

     }

   } else {

     blk->set_loop(innermost);

     innermost->def_locals()->add(blk->def_locals());

   }

 }

 // ------------------------------------------------------------------

 // ciTypeFlow::Loop::contains

 //

 // Returns true if lp is nested loop.

 bool ciTypeFlow::Loop::contains(ciTypeFlow::Loop* lp) const {

   assert(lp != NULL, "");

   if (this == lp || head() == lp->head()) return true;

   int depth1 = depth();

   int depth2 = lp->depth();

   if (depth1 > depth2)

     return false;

   while (depth1 < depth2) {

     depth2--;

     lp = lp->parent();

   }

   return this == lp;

 }

 // ------------------------------------------------------------------

 // ciTypeFlow::Loop::depth

 //

 // Loop depth

 int ciTypeFlow::Loop::depth() const {

   int dp = 0;

   for (Loop* lp = this->parent(); lp != NULL; lp = lp->parent())

     dp++;

   return dp;

 }

 #ifndef PRODUCT

 // ------------------------------------------------------------------

 // ciTypeFlow::Loop::print

 void ciTypeFlow::Loop::print(outputStream* st, int indent) const {

   for (int i = 0; i < indent; i++) st->print(" ");

   st->print("%d<-%d %s",

             is_root() ? 0 : this->head()->pre_order(),

             is_root() ? 0 : this->tail()->pre_order(),

             is_irreducible()?" irr":"");

   st->print(" defs: ");

   def_locals()->print_on(st, _head->outer()->method()->max_locals());

   st->cr();

   for (Loop* ch = child(); ch != NULL; ch = ch->sibling())

     ch->print(st, indent+2);

 }

 #endif

 // ------------------------------------------------------------------

 // ciTypeFlow::df_flow_types

 //

 // Perform the depth first type flow analysis. Helper for flow_types.

 void ciTypeFlow::df_flow_types(Block* start,

                                bool do_flow,

                                StateVector* temp_vector,

                                JsrSet* temp_set) {

   int dft_len = 100;

   GrowableArray<Block*> stk(arena(), dft_len, 0, NULL);

   ciBlock* dummy = _methodBlocks->make_dummy_block();

   JsrSet* root_set = new JsrSet(NULL, 0);

   Block* root_head = new (arena()) Block(this, dummy, root_set);

   Block* root_tail = new (arena()) Block(this, dummy, root_set);

   root_head->set_pre_order(0);

   root_head->set_post_order(0);

   root_tail->set_pre_order(max_jint);

   root_tail->set_post_order(max_jint);

   set_loop_tree_root(new (arena()) Loop(root_head, root_tail));

   stk.push(start);

   _next_pre_order = 0;  // initialize pre_order counter

   _rpo_list = NULL;

   int next_po = 0;      // initialize post_order counter

   // Compute RPO and the control flow graph

   int size;

   while ((size = stk.length()) > 0) {

     Block* blk = stk.top(); // Leave node on stack

     if (!blk->is_visited()) {

       // forward arc in graph

       assert (!blk->has_pre_order(), "");

       blk->set_next_pre_order();

       if (_next_pre_order >= MaxNodeLimit / 2) {

         // Too many basic blocks.  Bail out.

         // This can happen when try/finally constructs are nested to depth N,

         // and there is O(2**N) cloning of jsr bodies.  See bug 4697245!

         // "MaxNodeLimit / 2" is used because probably the parser will

         // generate at least twice that many nodes and bail out.

         record_failure("too many basic blocks");

         return;

       }

       if (do_flow) {

         flow_block(blk, temp_vector, temp_set);

         if (failing()) return; // Watch for bailouts.

       }

     } else if (!blk->is_post_visited()) {

       // cross or back arc

       for (SuccIter iter(blk); !iter.done(); iter.next()) {

         Block* succ = iter.succ();

         if (!succ->is_visited()) {

           stk.push(succ);

         }

       }

       if (stk.length() == size) {

         // There were no additional children, post visit node now

         stk.pop(); // Remove node from stack

         build_loop_tree(blk);

         blk->set_post_order(next_po++);   // Assign post order

         prepend_to_rpo_list(blk);

         assert(blk->is_post_visited(), "");

         if (blk->is_loop_head() && !blk->is_on_work_list()) {

           // Assume loop heads need more data flow

           add_to_work_list(blk);

         }