jdk8-mips64-public/hotspot: src/share/vm/ci/ciTypeFlow.cpp@8012aa3ccede (annotated)

src/share/vm/ci/ciTypeFlow.cpp@8012aa3ccede (annotated)

src/share/vm/ci/ciTypeFlow.cpp

Thu, 13 Jan 2011 22:15:41 -0800

author: never
date: Thu, 13 Jan 2011 22:15:41 -0800
changeset 2462: 8012aa3ccede
parent 2314: f95d63e2154a
child 2680: 322a41ec766c
permissions: -rw-r--r--

4926272: methodOopDesc::method_from_bcp is unsafe
Reviewed-by: coleenp, jrose, kvn, dcubed

 /*
  * Copyright (c) 2000, 2011, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  *
  */
 #include "precompiled.hpp"
 #include "ci/ciConstant.hpp"
 #include "ci/ciField.hpp"
 #include "ci/ciMethod.hpp"
 #include "ci/ciMethodData.hpp"
 #include "ci/ciObjArrayKlass.hpp"
 #include "ci/ciStreams.hpp"
 #include "ci/ciTypeArrayKlass.hpp"
 #include "ci/ciTypeFlow.hpp"
 #include "compiler/compileLog.hpp"
 #include "interpreter/bytecode.hpp"
 #include "interpreter/bytecodes.hpp"
 #include "memory/allocation.inline.hpp"
 #include "runtime/deoptimization.hpp"
 #include "utilities/growableArray.hpp"
 // 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.
     if (str->cur_bc() == Bytecodes::_invokedynamic) {
       trap(str, NULL,
            Deoptimization::make_trap_request
            (Deoptimization::Reason_uninitialized,
             Deoptimization::Action_reinterpret));
     } else {
       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 {
       assert(!obj->is_klass(), "must be java_mirror of klass");
       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::_invokedynamic:   do_invoke(str, false);          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(str);
         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(str);
         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,
 , 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(0 <= start_bci() && start_bci() < code_size() , err_msg("correct osr_bci argument: 0 <= %d < %d", start_bci(), code_size()));
   _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,
 ,
                                                            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()) {
     // %%% FIXME: ldc of Class can generate an exception
     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);
     }
   }
   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);
       }
       Loop* plp = lp->parent();
       if (plp == NULL) {
         // This only happens for some irreducible cases.  The parent
         // will be updated during a later pass.
         break;
       }
       lp = plp;
     }
     // 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(dft_len);
   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);
         }
       }
     } else {
       stk.pop(); // Remove post-visited node from stack
     }
   }
 }
 // ------------------------------------------------------------------
 // ciTypeFlow::flow_types
 //
 // Perform the type flow analysis, creating and cloning Blocks as
 // necessary.
 void ciTypeFlow::flow_types() {
   ResourceMark rm;
   StateVector* temp_vector = new StateVector(this);
   JsrSet* temp_set = new JsrSet(NULL, 16);
   // Create the method entry block.
   Block* start = block_at(start_bci(), temp_set);
   // Load the initial state into it.
   const StateVector* start_state = get_start_state();
   if (failing())  return;
   start->meet(start_state);
   // Depth first visit
   df_flow_types(start, true /*do flow*/, temp_vector, temp_set);
   if (failing())  return;
   assert(_rpo_list == start, "must be start");
   // Any loops found?
   if (loop_tree_root()->child() != NULL &&
       env()->comp_level() >= CompLevel_full_optimization) {
       // Loop optimizations are not performed on Tier1 compiles.
     bool changed = clone_loop_heads(loop_tree_root(), temp_vector, temp_set);
     // If some loop heads were cloned, recompute postorder and loop tree
     if (changed) {
       loop_tree_root()->set_child(NULL);
       for (Block* blk = _rpo_list; blk != NULL;) {
         Block* next = blk->rpo_next();
         blk->df_init();
         blk = next;
       }
       df_flow_types(start, false /*no flow*/, temp_vector, temp_set);
     }
   }
   if (CITraceTypeFlow) {
     tty->print_cr("\nLoop tree");
     loop_tree_root()->print();
   }
   // Continue flow analysis until fixed point reached
   debug_only(int max_block = _next_pre_order;)
   while (!work_list_empty()) {
     Block* blk = work_list_next();
     assert (blk->has_post_order(), "post order assigned above");
     flow_block(blk, temp_vector, temp_set);
     assert (max_block == _next_pre_order, "no new blocks");
     assert (!failing(), "no more bailouts");
   }
 }
 // ------------------------------------------------------------------
 // ciTypeFlow::map_blocks
 //
 // Create the block map, which indexes blocks in reverse post-order.
 void ciTypeFlow::map_blocks() {
   assert(_block_map == NULL, "single initialization");
   int block_ct = _next_pre_order;
   _block_map = NEW_ARENA_ARRAY(arena(), Block*, block_ct);
   assert(block_ct == block_count(), "");
   Block* blk = _rpo_list;
   for (int m = 0; m < block_ct; m++) {
     int rpo = blk->rpo();
     assert(rpo == m, "should be sequential");
     _block_map[rpo] = blk;
     blk = blk->rpo_next();
   }
   assert(blk == NULL, "should be done");
   for (int j = 0; j < block_ct; j++) {
     assert(_block_map[j] != NULL, "must not drop any blocks");
     Block* block = _block_map[j];
     // Remove dead blocks from successor lists:
     for (int e = 0; e <= 1; e++) {
       GrowableArray<Block*>* l = e? block->exceptions(): block->successors();
       for (int k = 0; k < l->length(); k++) {
         Block* s = l->at(k);
         if (!s->has_post_order()) {
           if (CITraceTypeFlow) {
             tty->print("Removing dead %s successor of #%d: ", (e? "exceptional":  "normal"), block->pre_order());
             s->print_value_on(tty);
             tty->cr();
           }
           l->remove(s);
           --k;
         }
       }
     }
   }
 }
 // ------------------------------------------------------------------
 // ciTypeFlow::get_block_for
 //
 // Find a block with this ciBlock which has a compatible JsrSet.
 // If no such block exists, create it, unless the option is no_create.
 // If the option is create_backedge_copy, always create a fresh backedge copy.
 ciTypeFlow::Block* ciTypeFlow::get_block_for(int ciBlockIndex, ciTypeFlow::JsrSet* jsrs, CreateOption option) {
   Arena* a = arena();
   GrowableArray<Block*>* blocks = _idx_to_blocklist[ciBlockIndex];
   if (blocks == NULL) {
     // Query only?
     if (option == no_create)  return NULL;
     // Allocate the growable array.
     blocks = new (a) GrowableArray<Block*>(a, 4, 0, NULL);
     _idx_to_blocklist[ciBlockIndex] = blocks;
   }
   if (option != create_backedge_copy) {
     int len = blocks->length();
     for (int i = 0; i < len; i++) {
       Block* block = blocks->at(i);
       if (!block->is_backedge_copy() && block->is_compatible_with(jsrs)) {
         return block;
       }
     }
   }
   // Query only?
   if (option == no_create)  return NULL;
   // We did not find a compatible block.  Create one.
   Block* new_block = new (a) Block(this, _methodBlocks->block(ciBlockIndex), jsrs);
   if (option == create_backedge_copy)  new_block->set_backedge_copy(true);
   blocks->append(new_block);
   return new_block;
 }
 // ------------------------------------------------------------------
 // ciTypeFlow::backedge_copy_count
 //
 int ciTypeFlow::backedge_copy_count(int ciBlockIndex, ciTypeFlow::JsrSet* jsrs) const {
   GrowableArray<Block*>* blocks = _idx_to_blocklist[ciBlockIndex];
   if (blocks == NULL) {
     return 0;
   }
   int count = 0;
   int len = blocks->length();
   for (int i = 0; i < len; i++) {
     Block* block = blocks->at(i);
     if (block->is_backedge_copy() && block->is_compatible_with(jsrs)) {
       count++;
     }
   }
   return count;
 }
 // ------------------------------------------------------------------
 // ciTypeFlow::do_flow
 //
 // Perform type inference flow analysis.
 void ciTypeFlow::do_flow() {
   if (CITraceTypeFlow) {
     tty->print_cr("\nPerforming flow analysis on method");
     method()->print();
     if (is_osr_flow())  tty->print(" at OSR bci %d", start_bci());
     tty->cr();
     method()->print_codes();
   }
   if (CITraceTypeFlow) {
     tty->print_cr("Initial CI Blocks");
     print_on(tty);
   }
   flow_types();
   // Watch for bailouts.
   if (failing()) {
     return;
   }
   map_blocks();
   if (CIPrintTypeFlow || CITraceTypeFlow) {
     rpo_print_on(tty);
   }
 }
 // ------------------------------------------------------------------
 // ciTypeFlow::record_failure()
 // The ciTypeFlow object keeps track of failure reasons separately from the ciEnv.
 // This is required because there is not a 1-1 relation between the ciEnv and
 // the TypeFlow passes within a compilation task.  For example, if the compiler
 // is considering inlining a method, it will request a TypeFlow.  If that fails,
 // the compilation as a whole may continue without the inlining.  Some TypeFlow
 // requests are not optional; if they fail the requestor is responsible for
 // copying the failure reason up to the ciEnv.  (See Parse::Parse.)
 void ciTypeFlow::record_failure(const char* reason) {
   if (env()->log() != NULL) {
     env()->log()->elem("failure reason='%s' phase='typeflow'", reason);
   }
   if (_failure_reason == NULL) {
     // Record the first failure reason.
     _failure_reason = reason;
   }
 }
 #ifndef PRODUCT
 // ------------------------------------------------------------------
 // ciTypeFlow::print_on
 void ciTypeFlow::print_on(outputStream* st) const {
   // Walk through CI blocks
   st->print_cr("********************************************************");
   st->print   ("TypeFlow for ");
   method()->name()->print_symbol_on(st);
   int limit_bci = code_size();
   st->print_cr("  %d bytes", limit_bci);
   ciMethodBlocks  *mblks = _methodBlocks;
   ciBlock* current = NULL;
   for (int bci = 0; bci < limit_bci; bci++) {
     ciBlock* blk = mblks->block_containing(bci);
     if (blk != NULL && blk != current) {
       current = blk;
       current->print_on(st);
       GrowableArray<Block*>* blocks = _idx_to_blocklist[blk->index()];
       int num_blocks = (blocks == NULL) ? 0 : blocks->length();
       if (num_blocks == 0) {
         st->print_cr("  No Blocks");
       } else {
         for (int i = 0; i < num_blocks; i++) {
           Block* block = blocks->at(i);
           block->print_on(st);
         }
       }
       st->print_cr("--------------------------------------------------------");
       st->cr();
     }
   }
   st->print_cr("********************************************************");
   st->cr();
 }
 void ciTypeFlow::rpo_print_on(outputStream* st) const {
   st->print_cr("********************************************************");
   st->print   ("TypeFlow for ");
   method()->name()->print_symbol_on(st);
   int limit_bci = code_size();
   st->print_cr("  %d bytes", limit_bci);
   for (Block* blk = _rpo_list; blk != NULL; blk = blk->rpo_next()) {
     blk->print_on(st);
     st->print_cr("--------------------------------------------------------");
     st->cr();
   }
   st->print_cr("********************************************************");
   st->cr();
 }
 #endif

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/ci/ciTypeFlow.cpp@8012aa3ccede (annotated)

src/share/vm/ci/ciTypeFlow.cpp