view src/share/vm/opto/parse1.cpp @ 24218:719853999215

Merge with jdk8u141-b15
author Doug Simon <doug.simon@oracle.com>
date Mon, 14 Aug 2017 23:20:38 +0200
parents f13e777eb255 3ff8d0b5a04b
children
line wrap: on
line source
/*
 * Copyright (c) 1997, 2016, 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 "compiler/compileLog.hpp"
#include "interpreter/linkResolver.hpp"
#include "oops/method.hpp"
#include "opto/addnode.hpp"
#include "opto/c2compiler.hpp"
#include "opto/idealGraphPrinter.hpp"
#include "opto/locknode.hpp"
#include "opto/memnode.hpp"
#include "opto/parse.hpp"
#include "opto/rootnode.hpp"
#include "opto/runtime.hpp"
#include "runtime/arguments.hpp"
#include "runtime/handles.inline.hpp"
#include "runtime/sharedRuntime.hpp"
#include "utilities/copy.hpp"

// Static array so we can figure out which bytecodes stop us from compiling
// the most. Some of the non-static variables are needed in bytecodeInfo.cpp
// and eventually should be encapsulated in a proper class (gri 8/18/98).

int nodes_created              = 0;
int methods_parsed             = 0;
int methods_seen               = 0;
int blocks_parsed              = 0;
int blocks_seen                = 0;

int explicit_null_checks_inserted = 0;
int explicit_null_checks_elided   = 0;
int all_null_checks_found         = 0, implicit_null_checks              = 0;
int implicit_null_throws          = 0;

int reclaim_idx  = 0;
int reclaim_in   = 0;
int reclaim_node = 0;

#ifndef PRODUCT
bool Parse::BytecodeParseHistogram::_initialized = false;
uint Parse::BytecodeParseHistogram::_bytecodes_parsed [Bytecodes::number_of_codes];
uint Parse::BytecodeParseHistogram::_nodes_constructed[Bytecodes::number_of_codes];
uint Parse::BytecodeParseHistogram::_nodes_transformed[Bytecodes::number_of_codes];
uint Parse::BytecodeParseHistogram::_new_values       [Bytecodes::number_of_codes];
#endif

//------------------------------print_statistics-------------------------------
#ifndef PRODUCT
void Parse::print_statistics() {
  tty->print_cr("--- Compiler Statistics ---");
  tty->print("Methods seen: %d  Methods parsed: %d", methods_seen, methods_parsed);
  tty->print("  Nodes created: %d", nodes_created);
  tty->cr();
  if (methods_seen != methods_parsed)
    tty->print_cr("Reasons for parse failures (NOT cumulative):");
  tty->print_cr("Blocks parsed: %d  Blocks seen: %d", blocks_parsed, blocks_seen);

  if( explicit_null_checks_inserted )
    tty->print_cr("%d original NULL checks - %d elided (%2d%%); optimizer leaves %d,", explicit_null_checks_inserted, explicit_null_checks_elided, (100*explicit_null_checks_elided)/explicit_null_checks_inserted, all_null_checks_found);
  if( all_null_checks_found )
    tty->print_cr("%d made implicit (%2d%%)", implicit_null_checks,
                  (100*implicit_null_checks)/all_null_checks_found);
  if( implicit_null_throws )
    tty->print_cr("%d implicit null exceptions at runtime",
                  implicit_null_throws);

  if( PrintParseStatistics && BytecodeParseHistogram::initialized() ) {
    BytecodeParseHistogram::print();
  }
}
#endif

//------------------------------ON STACK REPLACEMENT---------------------------

// Construct a node which can be used to get incoming state for
// on stack replacement.
Node *Parse::fetch_interpreter_state(int index,
                                     BasicType bt,
                                     Node *local_addrs,
                                     Node *local_addrs_base) {
  Node *mem = memory(Compile::AliasIdxRaw);
  Node *adr = basic_plus_adr( local_addrs_base, local_addrs, -index*wordSize );
  Node *ctl = control();

  // Very similar to LoadNode::make, except we handle un-aligned longs and
  // doubles on Sparc.  Intel can handle them just fine directly.
  Node *l = NULL;
  switch (bt) {                // Signature is flattened
  case T_INT:     l = new (C) LoadINode(ctl, mem, adr, TypeRawPtr::BOTTOM, TypeInt::INT,        MemNode::unordered); break;
  case T_FLOAT:   l = new (C) LoadFNode(ctl, mem, adr, TypeRawPtr::BOTTOM, Type::FLOAT,         MemNode::unordered); break;
  case T_ADDRESS: l = new (C) LoadPNode(ctl, mem, adr, TypeRawPtr::BOTTOM, TypeRawPtr::BOTTOM,  MemNode::unordered); break;
  case T_OBJECT:  l = new (C) LoadPNode(ctl, mem, adr, TypeRawPtr::BOTTOM, TypeInstPtr::BOTTOM, MemNode::unordered); break;
  case T_LONG:
  case T_DOUBLE: {
    // Since arguments are in reverse order, the argument address 'adr'
    // refers to the back half of the long/double.  Recompute adr.
    adr = basic_plus_adr(local_addrs_base, local_addrs, -(index+1)*wordSize);
    if (Matcher::misaligned_doubles_ok) {
      l = (bt == T_DOUBLE)
        ? (Node*)new (C) LoadDNode(ctl, mem, adr, TypeRawPtr::BOTTOM, Type::DOUBLE, MemNode::unordered)
        : (Node*)new (C) LoadLNode(ctl, mem, adr, TypeRawPtr::BOTTOM, TypeLong::LONG, MemNode::unordered);
    } else {
      l = (bt == T_DOUBLE)
        ? (Node*)new (C) LoadD_unalignedNode(ctl, mem, adr, TypeRawPtr::BOTTOM, MemNode::unordered)
        : (Node*)new (C) LoadL_unalignedNode(ctl, mem, adr, TypeRawPtr::BOTTOM, MemNode::unordered);
    }
    break;
  }
  default: ShouldNotReachHere();
  }
  return _gvn.transform(l);
}

// Helper routine to prevent the interpreter from handing
// unexpected typestate to an OSR method.
// The Node l is a value newly dug out of the interpreter frame.
// The type is the type predicted by ciTypeFlow.  Note that it is
// not a general type, but can only come from Type::get_typeflow_type.
// The safepoint is a map which will feed an uncommon trap.
Node* Parse::check_interpreter_type(Node* l, const Type* type,
                                    SafePointNode* &bad_type_exit) {

  const TypeOopPtr* tp = type->isa_oopptr();

  // TypeFlow may assert null-ness if a type appears unloaded.
  if (type == TypePtr::NULL_PTR ||
      (tp != NULL && !tp->klass()->is_loaded())) {
    // Value must be null, not a real oop.
    Node* chk = _gvn.transform( new (C) CmpPNode(l, null()) );
    Node* tst = _gvn.transform( new (C) BoolNode(chk, BoolTest::eq) );
    IfNode* iff = create_and_map_if(control(), tst, PROB_MAX, COUNT_UNKNOWN);
    set_control(_gvn.transform( new (C) IfTrueNode(iff) ));
    Node* bad_type = _gvn.transform( new (C) IfFalseNode(iff) );
    bad_type_exit->control()->add_req(bad_type);
    l = null();
  }

  // Typeflow can also cut off paths from the CFG, based on
  // types which appear unloaded, or call sites which appear unlinked.
  // When paths are cut off, values at later merge points can rise
  // toward more specific classes.  Make sure these specific classes
  // are still in effect.
  if (tp != NULL && tp->klass() != C->env()->Object_klass()) {
    // TypeFlow asserted a specific object type.  Value must have that type.
    Node* bad_type_ctrl = NULL;
    l = gen_checkcast(l, makecon(TypeKlassPtr::make(tp->klass())), &bad_type_ctrl);
    bad_type_exit->control()->add_req(bad_type_ctrl);
  }

  BasicType bt_l = _gvn.type(l)->basic_type();
  BasicType bt_t = type->basic_type();
  assert(_gvn.type(l)->higher_equal(type), "must constrain OSR typestate");
  return l;
}

// Helper routine which sets up elements of the initial parser map when
// performing a parse for on stack replacement.  Add values into map.
// The only parameter contains the address of a interpreter arguments.
void Parse::load_interpreter_state(Node* osr_buf) {
  int index;
  int max_locals = jvms()->loc_size();
  int max_stack  = jvms()->stk_size();


  // Mismatch between method and jvms can occur since map briefly held
  // an OSR entry state (which takes up one RawPtr word).
  assert(max_locals == method()->max_locals(), "sanity");
  assert(max_stack  >= method()->max_stack(),  "sanity");
  assert((int)jvms()->endoff() == TypeFunc::Parms + max_locals + max_stack, "sanity");
  assert((int)jvms()->endoff() == (int)map()->req(), "sanity");

  // Find the start block.
  Block* osr_block = start_block();
  assert(osr_block->start() == osr_bci(), "sanity");

  // Set initial BCI.
  set_parse_bci(osr_block->start());

  // Set initial stack depth.
  set_sp(osr_block->start_sp());

  // Check bailouts.  We currently do not perform on stack replacement
  // of loops in catch blocks or loops which branch with a non-empty stack.
  if (sp() != 0) {
    C->record_method_not_compilable("OSR starts with non-empty stack");
    return;
  }
  // Do not OSR inside finally clauses:
  if (osr_block->has_trap_at(osr_block->start())) {
    C->record_method_not_compilable("OSR starts with an immediate trap");
    return;
  }

  // Commute monitors from interpreter frame to compiler frame.
  assert(jvms()->monitor_depth() == 0, "should be no active locks at beginning of osr");
  int mcnt = osr_block->flow()->monitor_count();
  Node *monitors_addr = basic_plus_adr(osr_buf, osr_buf, (max_locals+mcnt*2-1)*wordSize);
  for (index = 0; index < mcnt; index++) {
    // Make a BoxLockNode for the monitor.
    Node *box = _gvn.transform(new (C) BoxLockNode(next_monitor()));


    // Displaced headers and locked objects are interleaved in the
    // temp OSR buffer.  We only copy the locked objects out here.
    // Fetch the locked object from the OSR temp buffer and copy to our fastlock node.
    Node *lock_object = fetch_interpreter_state(index*2, T_OBJECT, monitors_addr, osr_buf);
    // Try and copy the displaced header to the BoxNode
    Node *displaced_hdr = fetch_interpreter_state((index*2) + 1, T_ADDRESS, monitors_addr, osr_buf);


    store_to_memory(control(), box, displaced_hdr, T_ADDRESS, Compile::AliasIdxRaw, MemNode::unordered);

    // Build a bogus FastLockNode (no code will be generated) and push the
    // monitor into our debug info.
    const FastLockNode *flock = _gvn.transform(new (C) FastLockNode( 0, lock_object, box ))->as_FastLock();
    map()->push_monitor(flock);

    // If the lock is our method synchronization lock, tuck it away in
    // _sync_lock for return and rethrow exit paths.
    if (index == 0 && method()->is_synchronized()) {
      _synch_lock = flock;
    }
  }

  // Use the raw liveness computation to make sure that unexpected
  // values don't propagate into the OSR frame.
  MethodLivenessResult live_locals = method()->liveness_at_bci(osr_bci());
  if (!live_locals.is_valid()) {
    // Degenerate or breakpointed method.
    C->record_method_not_compilable("OSR in empty or breakpointed method");
    return;
  }

  // Extract the needed locals from the interpreter frame.
  Node *locals_addr = basic_plus_adr(osr_buf, osr_buf, (max_locals-1)*wordSize);

  // find all the locals that the interpreter thinks contain live oops
  const BitMap live_oops = method()->live_local_oops_at_bci(osr_bci());
  for (index = 0; index < max_locals; index++) {

    if (!live_locals.at(index)) {
      continue;
    }

    const Type *type = osr_block->local_type_at(index);

    if (type->isa_oopptr() != NULL) {

      // 6403625: Verify that the interpreter oopMap thinks that the oop is live
      // else we might load a stale oop if the MethodLiveness disagrees with the
      // result of the interpreter. If the interpreter says it is dead we agree
      // by making the value go to top.
      //

      if (!live_oops.at(index)) {
        if (C->log() != NULL) {
          C->log()->elem("OSR_mismatch local_index='%d'",index);
        }
        set_local(index, null());
        // and ignore it for the loads
        continue;
      }
    }

    // Filter out TOP, HALF, and BOTTOM.  (Cf. ensure_phi.)
    if (type == Type::TOP || type == Type::HALF) {
      continue;
    }
    // If the type falls to bottom, then this must be a local that
    // is mixing ints and oops or some such.  Forcing it to top
    // makes it go dead.
    if (type == Type::BOTTOM) {
      continue;
    }
    // Construct code to access the appropriate local.
    BasicType bt = type->basic_type();
    if (type == TypePtr::NULL_PTR) {
      // Ptr types are mixed together with T_ADDRESS but NULL is
      // really for T_OBJECT types so correct it.
      bt = T_OBJECT;
    }
    Node *value = fetch_interpreter_state(index, bt, locals_addr, osr_buf);
    set_local(index, value);
  }

  // Extract the needed stack entries from the interpreter frame.
  for (index = 0; index < sp(); index++) {
    const Type *type = osr_block->stack_type_at(index);
    if (type != Type::TOP) {
      // Currently the compiler bails out when attempting to on stack replace
      // at a bci with a non-empty stack.  We should not reach here.
      ShouldNotReachHere();
    }
  }

  // End the OSR migration
  make_runtime_call(RC_LEAF, OptoRuntime::osr_end_Type(),
                    CAST_FROM_FN_PTR(address, SharedRuntime::OSR_migration_end),
                    "OSR_migration_end", TypeRawPtr::BOTTOM,
                    osr_buf);

  // Now that the interpreter state is loaded, make sure it will match
  // at execution time what the compiler is expecting now:
  SafePointNode* bad_type_exit = clone_map();
  bad_type_exit->set_control(new (C) RegionNode(1));

  assert(osr_block->flow()->jsrs()->size() == 0, "should be no jsrs live at osr point");
  for (index = 0; index < max_locals; index++) {
    if (stopped())  break;
    Node* l = local(index);
    if (l->is_top())  continue;  // nothing here
    const Type *type = osr_block->local_type_at(index);
    if (type->isa_oopptr() != NULL) {
      if (!live_oops.at(index)) {
        // skip type check for dead oops
        continue;
      }
    }
    if (osr_block->flow()->local_type_at(index)->is_return_address()) {
      // In our current system it's illegal for jsr addresses to be
      // live into an OSR entry point because the compiler performs
      // inlining of jsrs.  ciTypeFlow has a bailout that detect this
      // case and aborts the compile if addresses are live into an OSR
      // entry point.  Because of that we can assume that any address
      // locals at the OSR entry point are dead.  Method liveness
      // isn't precise enought to figure out that they are dead in all
      // cases so simply skip checking address locals all
      // together. Any type check is guaranteed to fail since the
      // interpreter type is the result of a load which might have any
      // value and the expected type is a constant.
      continue;
    }
    set_local(index, check_interpreter_type(l, type, bad_type_exit));
  }

  for (index = 0; index < sp(); index++) {
    if (stopped())  break;
    Node* l = stack(index);
    if (l->is_top())  continue;  // nothing here
    const Type *type = osr_block->stack_type_at(index);
    set_stack(index, check_interpreter_type(l, type, bad_type_exit));
  }

  if (bad_type_exit->control()->req() > 1) {
    // Build an uncommon trap here, if any inputs can be unexpected.
    bad_type_exit->set_control(_gvn.transform( bad_type_exit->control() ));
    record_for_igvn(bad_type_exit->control());
    SafePointNode* types_are_good = map();
    set_map(bad_type_exit);
    // The unexpected type happens because a new edge is active
    // in the CFG, which typeflow had previously ignored.
    // E.g., Object x = coldAtFirst() && notReached()? "str": new Integer(123).
    // This x will be typed as Integer if notReached is not yet linked.
    // It could also happen due to a problem in ciTypeFlow analysis.
    uncommon_trap(Deoptimization::Reason_constraint,
                  Deoptimization::Action_reinterpret);
    set_map(types_are_good);
  }
}

//------------------------------Parse------------------------------------------
// Main parser constructor.
Parse::Parse(JVMState* caller, ciMethod* parse_method, float expected_uses)
  : _exits(caller)
{
  // Init some variables
  _caller = caller;
  _method = parse_method;
  _expected_uses = expected_uses;
  _depth = 1 + (caller->has_method() ? caller->depth() : 0);
  _wrote_final = false;
  _wrote_volatile = false;
  _alloc_with_final = NULL;
  _entry_bci = InvocationEntryBci;
  _tf = NULL;
  _block = NULL;
  _first_return = true;
  _replaced_nodes_for_exceptions = false;
  _new_idx = C->unique();
  debug_only(_block_count = -1);
  debug_only(_blocks = (Block*)-1);
#ifndef PRODUCT
  if (PrintCompilation || PrintOpto) {
    // Make sure I have an inline tree, so I can print messages about it.
    JVMState* ilt_caller = is_osr_parse() ? caller->caller() : caller;
    InlineTree::find_subtree_from_root(C->ilt(), ilt_caller, parse_method);
  }
  _max_switch_depth = 0;
  _est_switch_depth = 0;
#endif

  _tf = TypeFunc::make(method());
  _iter.reset_to_method(method());
  _flow = method()->get_flow_analysis();
  if (_flow->failing()) {
    C->record_method_not_compilable_all_tiers(_flow->failure_reason());
  }

#ifndef PRODUCT
  if (_flow->has_irreducible_entry()) {
    C->set_parsed_irreducible_loop(true);
  }
#endif

  if (_expected_uses <= 0) {
    _prof_factor = 1;
  } else {
    float prof_total = parse_method->interpreter_invocation_count();
    if (prof_total <= _expected_uses) {
      _prof_factor = 1;
    } else {
      _prof_factor = _expected_uses / prof_total;
    }
  }

  CompileLog* log = C->log();
  if (log != NULL) {
    log->begin_head("parse method='%d' uses='%g'",
                    log->identify(parse_method), expected_uses);
    if (depth() == 1 && C->is_osr_compilation()) {
      log->print(" osr_bci='%d'", C->entry_bci());
    }
    log->stamp();
    log->end_head();
  }

  // Accumulate deoptimization counts.
  // (The range_check and store_check counts are checked elsewhere.)
  ciMethodData* md = method()->method_data();
  for (uint reason = 0; reason < md->trap_reason_limit(); reason++) {
    uint md_count = md->trap_count(reason);
    if (md_count != 0) {
      if (md_count == md->trap_count_limit())
        md_count += md->overflow_trap_count();
      uint total_count = C->trap_count(reason);
      uint old_count   = total_count;
      total_count += md_count;
      // Saturate the add if it overflows.
      if (total_count < old_count || total_count < md_count)
        total_count = (uint)-1;
      C->set_trap_count(reason, total_count);
      if (log != NULL)
        log->elem("observe trap='%s' count='%d' total='%d'",
                  Deoptimization::trap_reason_name(reason),
                  md_count, total_count);
    }
  }
  // Accumulate total sum of decompilations, also.
  C->set_decompile_count(C->decompile_count() + md->decompile_count());

  _count_invocations = C->do_count_invocations();
  _method_data_update = C->do_method_data_update();

  if (log != NULL && method()->has_exception_handlers()) {
    log->elem("observe that='has_exception_handlers'");
  }

  assert(method()->can_be_compiled(),       "Can not parse this method, cutout earlier");
  assert(method()->has_balanced_monitors(), "Can not parse unbalanced monitors, cutout earlier");

  // Always register dependence if JVMTI is enabled, because
  // either breakpoint setting or hotswapping of methods may
  // cause deoptimization.
  if (C->env()->jvmti_can_hotswap_or_post_breakpoint()) {
    C->dependencies()->assert_evol_method(method());
  }

  methods_seen++;

  // Do some special top-level things.
  if (depth() == 1 && C->is_osr_compilation()) {
    _entry_bci = C->entry_bci();
    _flow = method()->get_osr_flow_analysis(osr_bci());
    if (_flow->failing()) {
      C->record_method_not_compilable(_flow->failure_reason());
#ifndef PRODUCT
      if (PrintOpto && (Verbose || WizardMode)) {
        tty->print_cr("OSR @%d type flow bailout: %s", _entry_bci, _flow->failure_reason());
        if (Verbose) {
          method()->print();
          method()->print_codes();
          _flow->print();
        }
      }
#endif
    }
    _tf = C->tf();     // the OSR entry type is different
  }

#ifdef ASSERT
  if (depth() == 1) {
    assert(C->is_osr_compilation() == this->is_osr_parse(), "OSR in sync");
    if (C->tf() != tf()) {
      MutexLockerEx ml(Compile_lock, Mutex::_no_safepoint_check_flag);
      assert(C->env()->system_dictionary_modification_counter_changed(),
             "Must invalidate if TypeFuncs differ");
    }
  } else {
    assert(!this->is_osr_parse(), "no recursive OSR");
  }
#endif

  methods_parsed++;
#ifndef PRODUCT
  // add method size here to guarantee that inlined methods are added too
  if (TimeCompiler)
    _total_bytes_compiled += method()->code_size();

  show_parse_info();
#endif

  if (failing()) {
    if (log)  log->done("parse");
    return;
  }

  gvn().set_type(root(), root()->bottom_type());
  gvn().transform(top());

  // Import the results of the ciTypeFlow.
  init_blocks();

  // Merge point for all normal exits
  build_exits();

  // Setup the initial JVM state map.
  SafePointNode* entry_map = create_entry_map();

  // Check for bailouts during map initialization
  if (failing() || entry_map == NULL) {
    if (log)  log->done("parse");
    return;
  }

  Node_Notes* caller_nn = C->default_node_notes();
  // Collect debug info for inlined calls unless -XX:-DebugInlinedCalls.
  if (DebugInlinedCalls || depth() == 1) {
    C->set_default_node_notes(make_node_notes(caller_nn));
  }

  if (is_osr_parse()) {
    Node* osr_buf = entry_map->in(TypeFunc::Parms+0);
    entry_map->set_req(TypeFunc::Parms+0, top());
    set_map(entry_map);
    load_interpreter_state(osr_buf);
  } else {
    set_map(entry_map);
    do_method_entry();
  }

  if (depth() == 1 && !failing()) {
    // Add check to deoptimize the nmethod if RTM state was changed
    rtm_deopt();
  }

  // Check for bailouts during method entry or RTM state check setup.
  if (failing()) {
    if (log)  log->done("parse");
    C->set_default_node_notes(caller_nn);
    return;
  }

  entry_map = map();  // capture any changes performed by method setup code
  assert(jvms()->endoff() == map()->req(), "map matches JVMS layout");

  // We begin parsing as if we have just encountered a jump to the
  // method entry.
  Block* entry_block = start_block();
  assert(entry_block->start() == (is_osr_parse() ? osr_bci() : 0), "");
  set_map_clone(entry_map);
  merge_common(entry_block, entry_block->next_path_num());

#ifndef PRODUCT
  BytecodeParseHistogram *parse_histogram_obj = new (C->env()->arena()) BytecodeParseHistogram(this, C);
  set_parse_histogram( parse_histogram_obj );
#endif

  // Parse all the basic blocks.
  do_all_blocks();

  C->set_default_node_notes(caller_nn);

  // Check for bailouts during conversion to graph
  if (failing()) {
    if (log)  log->done("parse");
    return;
  }

  // Fix up all exiting control flow.
  set_map(entry_map);
  do_exits();

  if (log)  log->done("parse nodes='%d' live='%d' memory='" SIZE_FORMAT "'",
                      C->unique(), C->live_nodes(), C->node_arena()->used());
}

//---------------------------do_all_blocks-------------------------------------
void Parse::do_all_blocks() {
  bool has_irreducible = flow()->has_irreducible_entry();

  // Walk over all blocks in Reverse Post-Order.
  while (true) {
    bool progress = false;
    for (int rpo = 0; rpo < block_count(); rpo++) {
      Block* block = rpo_at(rpo);

      if (block->is_parsed()) continue;

      if (!block->is_merged()) {
        // Dead block, no state reaches this block
        continue;
      }

      // Prepare to parse this block.
      load_state_from(block);

      if (stopped()) {
        // Block is dead.
        continue;
      }

      blocks_parsed++;

      progress = true;
      if (block->is_loop_head() || block->is_handler() || has_irreducible && !block->is_ready()) {
        // Not all preds have been parsed.  We must build phis everywhere.
        // (Note that dead locals do not get phis built, ever.)
        ensure_phis_everywhere();

        if (block->is_SEL_head() &&
            (UseLoopPredicate || LoopLimitCheck)) {
          // Add predicate to single entry (not irreducible) loop head.
          assert(!block->has_merged_backedge(), "only entry paths should be merged for now");
          // Need correct bci for predicate.
          // It is fine to set it here since do_one_block() will set it anyway.
          set_parse_bci(block->start());
          add_predicate();
          // Add new region for back branches.
          int edges = block->pred_count() - block->preds_parsed() + 1; // +1 for original region
          RegionNode *r = new (C) RegionNode(edges+1);
          _gvn.set_type(r, Type::CONTROL);
          record_for_igvn(r);
          r->init_req(edges, control());
          set_control(r);
          // Add new phis.
          ensure_phis_everywhere();
        }

        // Leave behind an undisturbed copy of the map, for future merges.
        set_map(clone_map());
      }

      if (control()->is_Region() && !block->is_loop_head() && !has_irreducible && !block->is_handler()) {
        // In the absence of irreducible loops, the Region and Phis
        // associated with a merge that doesn't involve a backedge can
        // be simplified now since the RPO parsing order guarantees
        // that any path which was supposed to reach here has already
        // been parsed or must be dead.
        Node* c = control();
        Node* result = _gvn.transform_no_reclaim(control());
        if (c != result && TraceOptoParse) {
          tty->print_cr("Block #%d replace %d with %d", block->rpo(), c->_idx, result->_idx);
        }
        if (result != top()) {
          record_for_igvn(result);
        }
      }

      // Parse the block.
      do_one_block();

      // Check for bailouts.
      if (failing())  return;
    }

    // with irreducible loops multiple passes might be necessary to parse everything
    if (!has_irreducible || !progress) {
      break;
    }
  }

  blocks_seen += block_count();

#ifndef PRODUCT
  // Make sure there are no half-processed blocks remaining.
  // Every remaining unprocessed block is dead and may be ignored now.
  for (int rpo = 0; rpo < block_count(); rpo++) {
    Block* block = rpo_at(rpo);
    if (!block->is_parsed()) {
      if (TraceOptoParse) {
        tty->print_cr("Skipped dead block %d at bci:%d", rpo, block->start());
      }
      assert(!block->is_merged(), "no half-processed blocks");
    }
  }
#endif
}

static Node* mask_int_value(Node* v, BasicType bt, PhaseGVN* gvn) {
  Compile* C = gvn->C;
  switch (bt) {
  case T_BYTE:
    v = gvn->transform(new (C) LShiftINode(v, gvn->intcon(24)));
    v = gvn->transform(new (C) RShiftINode(v, gvn->intcon(24)));
    break;
  case T_SHORT:
    v = gvn->transform(new (C) LShiftINode(v, gvn->intcon(16)));
    v = gvn->transform(new (C) RShiftINode(v, gvn->intcon(16)));
    break;
  case T_CHAR:
    v = gvn->transform(new (C) AndINode(v, gvn->intcon(0xFFFF)));
    break;
  case T_BOOLEAN:
    v = gvn->transform(new (C) AndINode(v, gvn->intcon(0x1)));
    break;
  }
  return v;
}

//-------------------------------build_exits----------------------------------
// Build normal and exceptional exit merge points.
void Parse::build_exits() {
  // make a clone of caller to prevent sharing of side-effects
  _exits.set_map(_exits.clone_map());
  _exits.clean_stack(_exits.sp());
  _exits.sync_jvms();

  RegionNode* region = new (C) RegionNode(1);
  record_for_igvn(region);
  gvn().set_type_bottom(region);
  _exits.set_control(region);

  // Note:  iophi and memphi are not transformed until do_exits.
  Node* iophi  = new (C) PhiNode(region, Type::ABIO);
  Node* memphi = new (C) PhiNode(region, Type::MEMORY, TypePtr::BOTTOM);
  gvn().set_type_bottom(iophi);
  gvn().set_type_bottom(memphi);
  _exits.set_i_o(iophi);
  _exits.set_all_memory(memphi);

  // Add a return value to the exit state.  (Do not push it yet.)
  if (tf()->range()->cnt() > TypeFunc::Parms) {
    const Type* ret_type = tf()->range()->field_at(TypeFunc::Parms);
    if (ret_type->isa_int()) {
      BasicType ret_bt = method()->return_type()->basic_type();
      if (ret_bt == T_BOOLEAN ||
          ret_bt == T_CHAR ||
          ret_bt == T_BYTE ||
          ret_bt == T_SHORT) {
        ret_type = TypeInt::INT;
      }
    }

    // Don't "bind" an unloaded return klass to the ret_phi. If the klass
    // becomes loaded during the subsequent parsing, the loaded and unloaded
    // types will not join when we transform and push in do_exits().
    const TypeOopPtr* ret_oop_type = ret_type->isa_oopptr();
    if (ret_oop_type && !ret_oop_type->klass()->is_loaded()) {
      ret_type = TypeOopPtr::BOTTOM;
    }
    int         ret_size = type2size[ret_type->basic_type()];
    Node*       ret_phi  = new (C) PhiNode(region, ret_type);
    gvn().set_type_bottom(ret_phi);
    _exits.ensure_stack(ret_size);
    assert((int)(tf()->range()->cnt() - TypeFunc::Parms) == ret_size, "good tf range");
    assert(method()->return_type()->size() == ret_size, "tf agrees w/ method");
    _exits.set_argument(0, ret_phi);  // here is where the parser finds it
    // Note:  ret_phi is not yet pushed, until do_exits.
  }
}


//----------------------------build_start_state-------------------------------
// Construct a state which contains only the incoming arguments from an
// unknown caller.  The method & bci will be NULL & InvocationEntryBci.
JVMState* Compile::build_start_state(StartNode* start, const TypeFunc* tf) {
  int        arg_size = tf->domain()->cnt();
  int        max_size = MAX2(arg_size, (int)tf->range()->cnt());
  JVMState*  jvms     = new (this) JVMState(max_size - TypeFunc::Parms);
  SafePointNode* map  = new (this) SafePointNode(max_size, NULL);
  record_for_igvn(map);
  assert(arg_size == TypeFunc::Parms + (is_osr_compilation() ? 1 : method()->arg_size()), "correct arg_size");
  Node_Notes* old_nn = default_node_notes();
  if (old_nn != NULL && has_method()) {
    Node_Notes* entry_nn = old_nn->clone(this);
    JVMState* entry_jvms = new(this) JVMState(method(), old_nn->jvms());
    entry_jvms->set_offsets(0);
    entry_jvms->set_bci(entry_bci());
    entry_nn->set_jvms(entry_jvms);
    set_default_node_notes(entry_nn);
  }
  uint i;
  for (i = 0; i < (uint)arg_size; i++) {
    Node* parm = initial_gvn()->transform(new (this) ParmNode(start, i));
    map->init_req(i, parm);
    // Record all these guys for later GVN.
    record_for_igvn(parm);
  }
  for (; i < map->req(); i++) {
    map->init_req(i, top());
  }
  assert(jvms->argoff() == TypeFunc::Parms, "parser gets arguments here");
  set_default_node_notes(old_nn);
  map->set_jvms(jvms);
  jvms->set_map(map);
  return jvms;
}

//-----------------------------make_node_notes---------------------------------
Node_Notes* Parse::make_node_notes(Node_Notes* caller_nn) {
  if (caller_nn == NULL)  return NULL;
  Node_Notes* nn = caller_nn->clone(C);
  JVMState* caller_jvms = nn->jvms();
  JVMState* jvms = new (C) JVMState(method(), caller_jvms);
  jvms->set_offsets(0);
  jvms->set_bci(_entry_bci);
  nn->set_jvms(jvms);
  return nn;
}


//--------------------------return_values--------------------------------------
void Compile::return_values(JVMState* jvms) {
  GraphKit kit(jvms);
  Node* ret = new (this) ReturnNode(TypeFunc::Parms,
                             kit.control(),
                             kit.i_o(),
                             kit.reset_memory(),
                             kit.frameptr(),
                             kit.returnadr());
  // Add zero or 1 return values
  int ret_size = tf()->range()->cnt() - TypeFunc::Parms;
  if (ret_size > 0) {
    kit.inc_sp(-ret_size);  // pop the return value(s)
    kit.sync_jvms();
    ret->add_req(kit.argument(0));
    // Note:  The second dummy edge is not needed by a ReturnNode.
  }
  // bind it to root
  root()->add_req(ret);
  record_for_igvn(ret);
  initial_gvn()->transform_no_reclaim(ret);
}

//------------------------rethrow_exceptions-----------------------------------
// Bind all exception states in the list into a single RethrowNode.
void Compile::rethrow_exceptions(JVMState* jvms) {
  GraphKit kit(jvms);
  if (!kit.has_exceptions())  return;  // nothing to generate
  // Load my combined exception state into the kit, with all phis transformed:
  SafePointNode* ex_map = kit.combine_and_pop_all_exception_states();
  Node* ex_oop = kit.use_exception_state(ex_map);
  RethrowNode* exit = new (this) RethrowNode(kit.control(),
                                      kit.i_o(), kit.reset_memory(),
                                      kit.frameptr(), kit.returnadr(),
                                      // like a return but with exception input
                                      ex_oop);
  // bind to root
  root()->add_req(exit);
  record_for_igvn(exit);
  initial_gvn()->transform_no_reclaim(exit);
}

//---------------------------do_exceptions-------------------------------------
// Process exceptions arising from the current bytecode.
// Send caught exceptions to the proper handler within this method.
// Unhandled exceptions feed into _exit.
void Parse::do_exceptions() {
  if (!has_exceptions())  return;

  if (failing()) {
    // Pop them all off and throw them away.
    while (pop_exception_state() != NULL) ;
    return;
  }

  PreserveJVMState pjvms(this, false);

  SafePointNode* ex_map;
  while ((ex_map = pop_exception_state()) != NULL) {
    if (!method()->has_exception_handlers()) {
      // Common case:  Transfer control outward.
      // Doing it this early allows the exceptions to common up
      // even between adjacent method calls.
      throw_to_exit(ex_map);
    } else {
      // Have to look at the exception first.
      assert(stopped(), "catch_inline_exceptions trashes the map");
      catch_inline_exceptions(ex_map);
      stop_and_kill_map();      // we used up this exception state; kill it
    }
  }

  // We now return to our regularly scheduled program:
}

//---------------------------throw_to_exit-------------------------------------
// Merge the given map into an exception exit from this method.
// The exception exit will handle any unlocking of receiver.
// The ex_oop must be saved within the ex_map, unlike merge_exception.
void Parse::throw_to_exit(SafePointNode* ex_map) {
  // Pop the JVMS to (a copy of) the caller.
  GraphKit caller;
  caller.set_map_clone(_caller->map());
  caller.set_bci(_caller->bci());
  caller.set_sp(_caller->sp());
  // Copy out the standard machine state:
  for (uint i = 0; i < TypeFunc::Parms; i++) {
    caller.map()->set_req(i, ex_map->in(i));
  }
  if (ex_map->has_replaced_nodes()) {
    _replaced_nodes_for_exceptions = true;
  }
  caller.map()->transfer_replaced_nodes_from(ex_map, _new_idx);
  // ...and the exception:
  Node*          ex_oop        = saved_ex_oop(ex_map);
  SafePointNode* caller_ex_map = caller.make_exception_state(ex_oop);
  // Finally, collect the new exception state in my exits:
  _exits.add_exception_state(caller_ex_map);
}

//------------------------------do_exits---------------------------------------
void Parse::do_exits() {
  set_parse_bci(InvocationEntryBci);

  // Now peephole on the return bits
  Node* region = _exits.control();
  _exits.set_control(gvn().transform(region));

  Node* iophi = _exits.i_o();
  _exits.set_i_o(gvn().transform(iophi));

  // On PPC64, also add MemBarRelease for constructors which write
  // volatile fields. As support_IRIW_for_not_multiple_copy_atomic_cpu
  // is set on PPC64, no sync instruction is issued after volatile
  // stores. We want to quarantee the same behaviour as on platforms
  // with total store order, although this is not required by the Java
  // memory model. So as with finals, we add a barrier here.
  if (wrote_final() PPC64_ONLY(|| (wrote_volatile() && method()->is_initializer()))) {
    // This method (which must be a constructor by the rules of Java)
    // wrote a final.  The effects of all initializations must be
    // committed to memory before any code after the constructor
    // publishes the reference to the newly constructor object.
    // Rather than wait for the publication, we simply block the
    // writes here.  Rather than put a barrier on only those writes
    // which are required to complete, we force all writes to complete.
    //
    // "All bets are off" unless the first publication occurs after a
    // normal return from the constructor.  We do not attempt to detect
    // such unusual early publications.  But no barrier is needed on
    // exceptional returns, since they cannot publish normally.
    //
    _exits.insert_mem_bar(Op_MemBarRelease, alloc_with_final());
#ifndef PRODUCT
    if (PrintOpto && (Verbose || WizardMode)) {
      method()->print_name();
      tty->print_cr(" writes finals and needs a memory barrier");
    }
#endif
  }

  for (MergeMemStream mms(_exits.merged_memory()); mms.next_non_empty(); ) {
    // transform each slice of the original memphi:
    mms.set_memory(_gvn.transform(mms.memory()));
  }

  if (tf()->range()->cnt() > TypeFunc::Parms) {
    const Type* ret_type = tf()->range()->field_at(TypeFunc::Parms);
    Node*       ret_phi  = _gvn.transform( _exits.argument(0) );
    if (!_exits.control()->is_top() && _gvn.type(ret_phi)->empty()) {
      // In case of concurrent class loading, the type we set for the
      // ret_phi in build_exits() may have been too optimistic and the
      // ret_phi may be top now.
      // Otherwise, we've encountered an error and have to mark the method as
      // not compilable. Just using an assertion instead would be dangerous
      // as this could lead to an infinite compile loop in non-debug builds.
      {
        MutexLockerEx ml(Compile_lock, Mutex::_no_safepoint_check_flag);
        if (C->env()->system_dictionary_modification_counter_changed()) {
          C->record_failure(C2Compiler::retry_class_loading_during_parsing());
        } else {
          C->record_method_not_compilable("Can't determine return type.");
        }
      }
      return;
    }
    if (ret_type->isa_int()) {
      BasicType ret_bt = method()->return_type()->basic_type();
      ret_phi = mask_int_value(ret_phi, ret_bt, &_gvn);
    }
    _exits.push_node(ret_type->basic_type(), ret_phi);
  }

  // Note:  Logic for creating and optimizing the ReturnNode is in Compile.

  // Unlock along the exceptional paths.
  // This is done late so that we can common up equivalent exceptions
  // (e.g., null checks) arising from multiple points within this method.
  // See GraphKit::add_exception_state, which performs the commoning.
  bool do_synch = method()->is_synchronized() && GenerateSynchronizationCode;

  // record exit from a method if compiled while Dtrace is turned on.
  if (do_synch || C->env()->dtrace_method_probes() || _replaced_nodes_for_exceptions) {
    // First move the exception list out of _exits:
    GraphKit kit(_exits.transfer_exceptions_into_jvms());
    SafePointNode* normal_map = kit.map();  // keep this guy safe
    // Now re-collect the exceptions into _exits:
    SafePointNode* ex_map;
    while ((ex_map = kit.pop_exception_state()) != NULL) {
      Node* ex_oop = kit.use_exception_state(ex_map);
      // Force the exiting JVM state to have this method at InvocationEntryBci.
      // The exiting JVM state is otherwise a copy of the calling JVMS.
      JVMState* caller = kit.jvms();
      JVMState* ex_jvms = caller->clone_shallow(C);
      ex_jvms->set_map(kit.clone_map());
      ex_jvms->map()->set_jvms(ex_jvms);
      ex_jvms->set_bci(   InvocationEntryBci);
      kit.set_jvms(ex_jvms);
      if (do_synch) {
        // Add on the synchronized-method box/object combo
        kit.map()->push_monitor(_synch_lock);
        // Unlock!
        kit.shared_unlock(_synch_lock->box_node(), _synch_lock->obj_node());
      }
      if (C->env()->dtrace_method_probes()) {
        kit.make_dtrace_method_exit(method());
      }
      if (_replaced_nodes_for_exceptions) {
        kit.map()->apply_replaced_nodes(_new_idx);
      }
      // Done with exception-path processing.
      ex_map = kit.make_exception_state(ex_oop);
      assert(ex_jvms->same_calls_as(ex_map->jvms()), "sanity");
      // Pop the last vestige of this method:
      ex_map->set_jvms(caller->clone_shallow(C));
      ex_map->jvms()->set_map(ex_map);
      _exits.push_exception_state(ex_map);
    }
    assert(_exits.map() == normal_map, "keep the same return state");
  }

  {
    // Capture very early exceptions (receiver null checks) from caller JVMS
    GraphKit caller(_caller);
    SafePointNode* ex_map;
    while ((ex_map = caller.pop_exception_state()) != NULL) {
      _exits.add_exception_state(ex_map);
    }
  }
  _exits.map()->apply_replaced_nodes(_new_idx);
}

//-----------------------------create_entry_map-------------------------------
// Initialize our parser map to contain the types at method entry.
// For OSR, the map contains a single RawPtr parameter.
// Initial monitor locking for sync. methods is performed by do_method_entry.
SafePointNode* Parse::create_entry_map() {
  // Check for really stupid bail-out cases.
  uint len = TypeFunc::Parms + method()->max_locals() + method()->max_stack();
  if (len >= 32760) {
    C->record_method_not_compilable_all_tiers("too many local variables");
    return NULL;
  }

  // clear current replaced nodes that are of no use from here on (map was cloned in build_exits).
  _caller->map()->delete_replaced_nodes();

  // If this is an inlined method, we may have to do a receiver null check.
  if (_caller->has_method() && is_normal_parse() && !method()->is_static()) {
    GraphKit kit(_caller);
    kit.null_check_receiver_before_call(method());
    _caller = kit.transfer_exceptions_into_jvms();
    if (kit.stopped()) {
      _exits.add_exception_states_from(_caller);
      _exits.set_jvms(_caller);
      return NULL;
    }
  }

  assert(method() != NULL, "parser must have a method");

  // Create an initial safepoint to hold JVM state during parsing
  JVMState* jvms = new (C) JVMState(method(), _caller->has_method() ? _caller : NULL);
  set_map(new (C) SafePointNode(len, jvms));
  jvms->set_map(map());
  record_for_igvn(map());
  assert(jvms->endoff() == len, "correct jvms sizing");

  SafePointNode* inmap = _caller->map();
  assert(inmap != NULL, "must have inmap");
  // In case of null check on receiver above
  map()->transfer_replaced_nodes_from(inmap, _new_idx);

  uint i;

  // Pass thru the predefined input parameters.
  for (i = 0; i < TypeFunc::Parms; i++) {
    map()->init_req(i, inmap->in(i));
  }

  if (depth() == 1) {
    assert(map()->memory()->Opcode() == Op_Parm, "");
    // Insert the memory aliasing node
    set_all_memory(reset_memory());
  }
  assert(merged_memory(), "");

  // Now add the locals which are initially bound to arguments:
  uint arg_size = tf()->domain()->cnt();
  ensure_stack(arg_size - TypeFunc::Parms);  // OSR methods have funny args
  for (i = TypeFunc::Parms; i < arg_size; i++) {
    map()->init_req(i, inmap->argument(_caller, i - TypeFunc::Parms));
  }

  // Clear out the rest of the map (locals and stack)
  for (i = arg_size; i < len; i++) {
    map()->init_req(i, top());
  }

  SafePointNode* entry_map = stop();
  return entry_map;
}

//-----------------------------do_method_entry--------------------------------
// Emit any code needed in the pseudo-block before BCI zero.
// The main thing to do is lock the receiver of a synchronized method.
void Parse::do_method_entry() {
  set_parse_bci(InvocationEntryBci); // Pseudo-BCP
  set_sp(0);                      // Java Stack Pointer

  NOT_PRODUCT( count_compiled_calls(true/*at_method_entry*/, false/*is_inline*/); )

  if (C->env()->dtrace_method_probes()) {
    make_dtrace_method_entry(method());
  }

  // If the method is synchronized, we need to construct a lock node, attach
  // it to the Start node, and pin it there.
  if (method()->is_synchronized()) {
    // Insert a FastLockNode right after the Start which takes as arguments
    // the current thread pointer, the "this" pointer & the address of the
    // stack slot pair used for the lock.  The "this" pointer is a projection
    // off the start node, but the locking spot has to be constructed by
    // creating a ConLNode of 0, and boxing it with a BoxLockNode.  The BoxLockNode
    // becomes the second argument to the FastLockNode call.  The
    // FastLockNode becomes the new control parent to pin it to the start.

    // Setup Object Pointer
    Node *lock_obj = NULL;
    if(method()->is_static()) {
      ciInstance* mirror = _method->holder()->java_mirror();
      const TypeInstPtr *t_lock = TypeInstPtr::make(mirror);
      lock_obj = makecon(t_lock);
    } else {                  // Else pass the "this" pointer,
      lock_obj = local(0);    // which is Parm0 from StartNode
    }
    // Clear out dead values from the debug info.
    kill_dead_locals();
    // Build the FastLockNode
    _synch_lock = shared_lock(lock_obj);
  }

  // Feed profiling data for parameters to the type system so it can
  // propagate it as speculative types
  record_profiled_parameters_for_speculation();

  if (depth() == 1) {
    increment_and_test_invocation_counter(Tier2CompileThreshold);
  }
}

//------------------------------init_blocks------------------------------------
// Initialize our parser map to contain the types/monitors at method entry.
void Parse::init_blocks() {
  // Create the blocks.
  _block_count = flow()->block_count();
  _blocks = NEW_RESOURCE_ARRAY(Block, _block_count);
  Copy::zero_to_bytes(_blocks, sizeof(Block)*_block_count);

  int rpo;

  // Initialize the structs.
  for (rpo = 0; rpo < block_count(); rpo++) {
    Block* block = rpo_at(rpo);
    block->init_node(this, rpo);
  }

  // Collect predecessor and successor information.
  for (rpo = 0; rpo < block_count(); rpo++) {
    Block* block = rpo_at(rpo);
    block->init_graph(this);
  }
}

//-------------------------------init_node-------------------------------------
void Parse::Block::init_node(Parse* outer, int rpo) {
  _flow = outer->flow()->rpo_at(rpo);
  _pred_count = 0;
  _preds_parsed = 0;
  _count = 0;
  assert(pred_count() == 0 && preds_parsed() == 0, "sanity");
  assert(!(is_merged() || is_parsed() || is_handler() || has_merged_backedge()), "sanity");
  assert(_live_locals.size() == 0, "sanity");

  // entry point has additional predecessor
  if (flow()->is_start())  _pred_count++;
  assert(flow()->is_start() == (this == outer->start_block()), "");
}

//-------------------------------init_graph------------------------------------
void Parse::Block::init_graph(Parse* outer) {
  // Create the successor list for this parser block.
  GrowableArray<ciTypeFlow::Block*>* tfs = flow()->successors();
  GrowableArray<ciTypeFlow::Block*>* tfe = flow()->exceptions();
  int ns = tfs->length();
  int ne = tfe->length();
  _num_successors = ns;
  _all_successors = ns+ne;
  _successors = (ns+ne == 0) ? NULL : NEW_RESOURCE_ARRAY(Block*, ns+ne);
  int p = 0;
  for (int i = 0; i < ns+ne; i++) {
    ciTypeFlow::Block* tf2 = (i < ns) ? tfs->at(i) : tfe->at(i-ns);
    Block* block2 = outer->rpo_at(tf2->rpo());
    _successors[i] = block2;

    // Accumulate pred info for the other block, too.
    if (i < ns) {
      block2->_pred_count++;
    } else {
      block2->_is_handler = true;
    }

    #ifdef ASSERT
    // A block's successors must be distinguishable by BCI.
    // That is, no bytecode is allowed to branch to two different
    // clones of the same code location.
    for (int j = 0; j < i; j++) {
      Block* block1 = _successors[j];
      if (block1 == block2)  continue;  // duplicates are OK
      assert(block1->start() != block2->start(), "successors have unique bcis");
    }
    #endif
  }

  // Note: We never call next_path_num along exception paths, so they
  // never get processed as "ready".  Also, the input phis of exception
  // handlers get specially processed, so that
}

//---------------------------successor_for_bci---------------------------------
Parse::Block* Parse::Block::successor_for_bci(int bci) {
  for (int i = 0; i < all_successors(); i++) {
    Block* block2 = successor_at(i);
    if (block2->start() == bci)  return block2;
  }
  // We can actually reach here if ciTypeFlow traps out a block
  // due to an unloaded class, and concurrently with compilation the
  // class is then loaded, so that a later phase of the parser is
  // able to see more of the bytecode CFG.  Or, the flow pass and
  // the parser can have a minor difference of opinion about executability
  // of bytecodes.  For example, "obj.field = null" is executable even
  // if the field's type is an unloaded class; the flow pass used to
  // make a trap for such code.
  return NULL;
}


//-----------------------------stack_type_at-----------------------------------
const Type* Parse::Block::stack_type_at(int i) const {
  return get_type(flow()->stack_type_at(i));
}


//-----------------------------local_type_at-----------------------------------
const Type* Parse::Block::local_type_at(int i) const {
  // Make dead locals fall to bottom.
  if (_live_locals.size() == 0) {
    MethodLivenessResult live_locals = flow()->outer()->method()->liveness_at_bci(start());
    // This bitmap can be zero length if we saw a breakpoint.
    // In such cases, pretend they are all live.
    ((Block*)this)->_live_locals = live_locals;
  }
  if (_live_locals.size() > 0 && !_live_locals.at(i))
    return Type::BOTTOM;

  return get_type(flow()->local_type_at(i));
}


#ifndef PRODUCT

//----------------------------name_for_bc--------------------------------------
// helper method for BytecodeParseHistogram
static const char* name_for_bc(int i) {
  return Bytecodes::is_defined(i) ? Bytecodes::name(Bytecodes::cast(i)) : "xxxunusedxxx";
}

//----------------------------BytecodeParseHistogram------------------------------------
Parse::BytecodeParseHistogram::BytecodeParseHistogram(Parse *p, Compile *c) {
  _parser   = p;
  _compiler = c;
  if( ! _initialized ) { _initialized = true; reset(); }
}

//----------------------------current_count------------------------------------
int Parse::BytecodeParseHistogram::current_count(BPHType bph_type) {
  switch( bph_type ) {
  case BPH_transforms: { return _parser->gvn().made_progress(); }
  case BPH_values:     { return _parser->gvn().made_new_values(); }
  default: { ShouldNotReachHere(); return 0; }
  }
}

//----------------------------initialized--------------------------------------
bool Parse::BytecodeParseHistogram::initialized() { return _initialized; }

//----------------------------reset--------------------------------------------
void Parse::BytecodeParseHistogram::reset() {
  int i = Bytecodes::number_of_codes;
  while (i-- > 0) { _bytecodes_parsed[i] = 0; _nodes_constructed[i] = 0; _nodes_transformed[i] = 0; _new_values[i] = 0; }
}

//----------------------------set_initial_state--------------------------------
// Record info when starting to parse one bytecode
void Parse::BytecodeParseHistogram::set_initial_state( Bytecodes::Code bc ) {
  if( PrintParseStatistics && !_parser->is_osr_parse() ) {
    _initial_bytecode    = bc;
    _initial_node_count  = _compiler->unique();
    _initial_transforms  = current_count(BPH_transforms);
    _initial_values      = current_count(BPH_values);
  }
}

//----------------------------record_change--------------------------------
// Record results of parsing one bytecode
void Parse::BytecodeParseHistogram::record_change() {
  if( PrintParseStatistics && !_parser->is_osr_parse() ) {
    ++_bytecodes_parsed[_initial_bytecode];
    _nodes_constructed [_initial_bytecode] += (_compiler->unique() - _initial_node_count);
    _nodes_transformed [_initial_bytecode] += (current_count(BPH_transforms) - _initial_transforms);
    _new_values        [_initial_bytecode] += (current_count(BPH_values)     - _initial_values);
  }
}


//----------------------------print--------------------------------------------
void Parse::BytecodeParseHistogram::print(float cutoff) {
  ResourceMark rm;
  // print profile
  int total  = 0;
  int i      = 0;
  for( i = 0; i < Bytecodes::number_of_codes; ++i ) { total += _bytecodes_parsed[i]; }
  int abs_sum = 0;
  tty->cr();   //0123456789012345678901234567890123456789012345678901234567890123456789
  tty->print_cr("Histogram of %d parsed bytecodes:", total);
  if( total == 0 ) { return; }
  tty->cr();
  tty->print_cr("absolute:  count of compiled bytecodes of this type");
  tty->print_cr("relative:  percentage contribution to compiled nodes");
  tty->print_cr("nodes   :  Average number of nodes constructed per bytecode");
  tty->print_cr("rnodes  :  Significance towards total nodes constructed, (nodes*relative)");
  tty->print_cr("transforms: Average amount of tranform progress per bytecode compiled");
  tty->print_cr("values  :  Average number of node values improved per bytecode");
  tty->print_cr("name    :  Bytecode name");
  tty->cr();
  tty->print_cr("  absolute  relative   nodes  rnodes  transforms  values   name");
  tty->print_cr("----------------------------------------------------------------------");
  while (--i > 0) {
    int       abs = _bytecodes_parsed[i];
    float     rel = abs * 100.0F / total;
    float   nodes = _bytecodes_parsed[i] == 0 ? 0 : (1.0F * _nodes_constructed[i])/_bytecodes_parsed[i];
    float  rnodes = _bytecodes_parsed[i] == 0 ? 0 :  rel * nodes;
    float  xforms = _bytecodes_parsed[i] == 0 ? 0 : (1.0F * _nodes_transformed[i])/_bytecodes_parsed[i];
    float  values = _bytecodes_parsed[i] == 0 ? 0 : (1.0F * _new_values       [i])/_bytecodes_parsed[i];
    if (cutoff <= rel) {
      tty->print_cr("%10d  %7.2f%%  %6.1f  %6.2f   %6.1f   %6.1f     %s", abs, rel, nodes, rnodes, xforms, values, name_for_bc(i));
      abs_sum += abs;
    }
  }
  tty->print_cr("----------------------------------------------------------------------");
  float rel_sum = abs_sum * 100.0F / total;
  tty->print_cr("%10d  %7.2f%%    (cutoff = %.2f%%)", abs_sum, rel_sum, cutoff);
  tty->print_cr("----------------------------------------------------------------------");
  tty->cr();
}
#endif

//----------------------------load_state_from----------------------------------
// Load block/map/sp.  But not do not touch iter/bci.
void Parse::load_state_from(Block* block) {
  set_block(block);
  // load the block's JVM state:
  set_map(block->start_map());
  set_sp( block->start_sp());
}


//-----------------------------record_state------------------------------------
void Parse::Block::record_state(Parse* p) {
  assert(!is_merged(), "can only record state once, on 1st inflow");
  assert(start_sp() == p->sp(), "stack pointer must agree with ciTypeFlow");
  set_start_map(p->stop());
}


//------------------------------do_one_block-----------------------------------
void Parse::do_one_block() {
  if (TraceOptoParse) {
    Block *b = block();
    int ns = b->num_successors();
    int nt = b->all_successors();

    tty->print("Parsing block #%d at bci [%d,%d), successors: ",
                  block()->rpo(), block()->start(), block()->limit());
    for (int i = 0; i < nt; i++) {
      tty->print((( i < ns) ? " %d" : " %d(e)"), b->successor_at(i)->rpo());
    }
    if (b->is_loop_head()) tty->print("  lphd");
    tty->cr();
  }

  assert(block()->is_merged(), "must be merged before being parsed");
  block()->mark_parsed();
  ++_blocks_parsed;

  // Set iterator to start of block.
  iter().reset_to_bci(block()->start());

  CompileLog* log = C->log();

  // Parse bytecodes
  while (!stopped() && !failing()) {
    iter().next();

    // Learn the current bci from the iterator:
    set_parse_bci(iter().cur_bci());

    if (bci() == block()->limit()) {
      // Do not walk into the next block until directed by do_all_blocks.
      merge(bci());
      break;
    }
    assert(bci() < block()->limit(), "bci still in block");

    if (log != NULL) {
      // Output an optional context marker, to help place actions
      // that occur during parsing of this BC.  If there is no log
      // output until the next context string, this context string
      // will be silently ignored.
      log->set_context("bc code='%d' bci='%d'", (int)bc(), bci());
    }

    if (block()->has_trap_at(bci())) {
      // We must respect the flow pass's traps, because it will refuse
      // to produce successors for trapping blocks.
      int trap_index = block()->flow()->trap_index();
      assert(trap_index != 0, "trap index must be valid");
      uncommon_trap(trap_index);
      break;
    }

    NOT_PRODUCT( parse_histogram()->set_initial_state(bc()); );

#ifdef ASSERT
    int pre_bc_sp = sp();
    int inputs, depth;
    bool have_se = !stopped() && compute_stack_effects(inputs, depth);
    assert(!have_se || pre_bc_sp >= inputs, err_msg_res("have enough stack to execute this BC: pre_bc_sp=%d, inputs=%d", pre_bc_sp, inputs));
#endif //ASSERT

    do_one_bytecode();

    assert(!have_se || stopped() || failing() || (sp() - pre_bc_sp) == depth,
           err_msg_res("incorrect depth prediction: sp=%d, pre_bc_sp=%d, depth=%d", sp(), pre_bc_sp, depth));

    do_exceptions();

    NOT_PRODUCT( parse_histogram()->record_change(); );

    if (log != NULL)
      log->clear_context();  // skip marker if nothing was printed

    // Fall into next bytecode.  Each bytecode normally has 1 sequential
    // successor which is typically made ready by visiting this bytecode.
    // If the successor has several predecessors, then it is a merge
    // point, starts a new basic block, and is handled like other basic blocks.
  }
}


//------------------------------merge------------------------------------------
void Parse::set_parse_bci(int bci) {
  set_bci(bci);
  Node_Notes* nn = C->default_node_notes();
  if (nn == NULL)  return;

  // Collect debug info for inlined calls unless -XX:-DebugInlinedCalls.
  if (!DebugInlinedCalls && depth() > 1) {
    return;
  }

  // Update the JVMS annotation, if present.
  JVMState* jvms = nn->jvms();
  if (jvms != NULL && jvms->bci() != bci) {
    // Update the JVMS.
    jvms = jvms->clone_shallow(C);
    jvms->set_bci(bci);
    nn->set_jvms(jvms);
  }
}

//------------------------------merge------------------------------------------
// Merge the current mapping into the basic block starting at bci
void Parse::merge(int target_bci) {
  Block* target = successor_for_bci(target_bci);
  if (target == NULL) { handle_missing_successor(target_bci); return; }
  assert(!target->is_ready(), "our arrival must be expected");
  int pnum = target->next_path_num();
  merge_common(target, pnum);
}

//-------------------------merge_new_path--------------------------------------
// Merge the current mapping into the basic block, using a new path
void Parse::merge_new_path(int target_bci) {
  Block* target = successor_for_bci(target_bci);
  if (target == NULL) { handle_missing_successor(target_bci); return; }
  assert(!target->is_ready(), "new path into frozen graph");
  int pnum = target->add_new_path();
  merge_common(target, pnum);
}

//-------------------------merge_exception-------------------------------------
// Merge the current mapping into the basic block starting at bci
// The ex_oop must be pushed on the stack, unlike throw_to_exit.
void Parse::merge_exception(int target_bci) {
  assert(sp() == 1, "must have only the throw exception on the stack");
  Block* target = successor_for_bci(target_bci);
  if (target == NULL) { handle_missing_successor(target_bci); return; }
  assert(target->is_handler(), "exceptions are handled by special blocks");
  int pnum = target->add_new_path();
  merge_common(target, pnum);
}

//--------------------handle_missing_successor---------------------------------
void Parse::handle_missing_successor(int target_bci) {
#ifndef PRODUCT
  Block* b = block();
  int trap_bci = b->flow()->has_trap()? b->flow()->trap_bci(): -1;
  tty->print_cr("### Missing successor at bci:%d for block #%d (trap_bci:%d)", target_bci, b->rpo(), trap_bci);
#endif
  ShouldNotReachHere();
}

//--------------------------merge_common---------------------------------------
void Parse::merge_common(Parse::Block* target, int pnum) {
  if (TraceOptoParse) {
    tty->print("Merging state at block #%d bci:%d", target->rpo(), target->start());
  }

  // Zap extra stack slots to top
  assert(sp() == target->start_sp(), "");
  clean_stack(sp());

  if (!target->is_merged()) {   // No prior mapping at this bci
    if (TraceOptoParse) { tty->print(" with empty state");  }

    // If this path is dead, do not bother capturing it as a merge.
    // It is "as if" we had 1 fewer predecessors from the beginning.
    if (stopped()) {
      if (TraceOptoParse)  tty->print_cr(", but path is dead and doesn't count");
      return;
    }

    // Record that a new block has been merged.
    ++_blocks_merged;

    // Make a region if we know there are multiple or unpredictable inputs.
    // (Also, if this is a plain fall-through, we might see another region,
    // which must not be allowed into this block's map.)
    if (pnum > PhiNode::Input         // Known multiple inputs.
        || target->is_handler()       // These have unpredictable inputs.
        || target->is_loop_head()     // Known multiple inputs
        || control()->is_Region()) {  // We must hide this guy.

      int current_bci = bci();
      set_parse_bci(target->start()); // Set target bci
      if (target->is_SEL_head()) {
        DEBUG_ONLY( target->mark_merged_backedge(block()); )
        if (target->start() == 0) {
          // Add loop predicate for the special case when
          // there are backbranches to the method entry.
          add_predicate();
        }
      }
      // Add a Region to start the new basic block.  Phis will be added
      // later lazily.
      int edges = target->pred_count();
      if (edges < pnum)  edges = pnum;  // might be a new path!
      RegionNode *r = new (C) RegionNode(edges+1);
      gvn().set_type(r, Type::CONTROL);
      record_for_igvn(r);
      // zap all inputs to NULL for debugging (done in Node(uint) constructor)
      // for (int j = 1; j < edges+1; j++) { r->init_req(j, NULL); }
      r->init_req(pnum, control());
      set_control(r);
      set_parse_bci(current_bci); // Restore bci
    }

    // Convert the existing Parser mapping into a mapping at this bci.
    store_state_to(target);
    assert(target->is_merged(), "do not come here twice");

  } else {                      // Prior mapping at this bci
    if (TraceOptoParse) {  tty->print(" with previous state"); }
#ifdef ASSERT
    if (target->is_SEL_head()) {
      target->mark_merged_backedge(block());
    }
#endif
    // We must not manufacture more phis if the target is already parsed.
    bool nophi = target->is_parsed();

    SafePointNode* newin = map();// Hang on to incoming mapping
    Block* save_block = block(); // Hang on to incoming block;
    load_state_from(target);    // Get prior mapping

    assert(newin->jvms()->locoff() == jvms()->locoff(), "JVMS layouts agree");
    assert(newin->jvms()->stkoff() == jvms()->stkoff(), "JVMS layouts agree");
    assert(newin->jvms()->monoff() == jvms()->monoff(), "JVMS layouts agree");
    assert(newin->jvms()->endoff() == jvms()->endoff(), "JVMS layouts agree");

    // Iterate over my current mapping and the old mapping.
    // Where different, insert Phi functions.
    // Use any existing Phi functions.
    assert(control()->is_Region(), "must be merging to a region");
    RegionNode* r = control()->as_Region();

    // Compute where to merge into
    // Merge incoming control path
    r->init_req(pnum, newin->control());

    if (pnum == 1) {            // Last merge for this Region?
      if (!block()->flow()->is_irreducible_entry()) {
        Node* result = _gvn.transform_no_reclaim(r);
        if (r != result && TraceOptoParse) {
          tty->print_cr("Block #%d replace %d with %d", block()->rpo(), r->_idx, result->_idx);
        }
      }
      record_for_igvn(r);
    }

    // Update all the non-control inputs to map:
    assert(TypeFunc::Parms == newin->jvms()->locoff(), "parser map should contain only youngest jvms");
    bool check_elide_phi = target->is_SEL_backedge(save_block);
    for (uint j = 1; j < newin->req(); j++) {
      Node* m = map()->in(j);   // Current state of target.
      Node* n = newin->in(j);   // Incoming change to target state.
      PhiNode* phi;
      if (m->is_Phi() && m->as_Phi()->region() == r)
        phi = m->as_Phi();
      else
        phi = NULL;
      if (m != n) {             // Different; must merge
        switch (j) {
        // Frame pointer and Return Address never changes
        case TypeFunc::FramePtr:// Drop m, use the original value
        case TypeFunc::ReturnAdr:
          break;
        case TypeFunc::Memory:  // Merge inputs to the MergeMem node
          assert(phi == NULL, "the merge contains phis, not vice versa");
          merge_memory_edges(n->as_MergeMem(), pnum, nophi);
          continue;
        default:                // All normal stuff
          if (phi == NULL) {
            const JVMState* jvms = map()->jvms();
            if (EliminateNestedLocks &&
                jvms->is_mon(j) && jvms->is_monitor_box(j)) {
              // BoxLock nodes are not commoning.
              // Use old BoxLock node as merged box.
              assert(newin->jvms()->is_monitor_box(j), "sanity");
              // This assert also tests that nodes are BoxLock.
              assert(BoxLockNode::same_slot(n, m), "sanity");
              C->gvn_replace_by(n, m);
            } else if (!check_elide_phi || !target->can_elide_SEL_phi(j)) {
              phi = ensure_phi(j, nophi);
            }
          }
          break;
        }
      }
      // At this point, n might be top if:
      //  - there is no phi (because TypeFlow detected a conflict), or
      //  - the corresponding control edges is top (a dead incoming path)
      // It is a bug if we create a phi which sees a garbage value on a live path.

      if (phi != NULL) {
        assert(n != top() || r->in(pnum) == top(), "live value must not be garbage");
        assert(phi->region() == r, "");
        phi->set_req(pnum, n);  // Then add 'n' to the merge
        if (pnum == PhiNode::Input) {
          // Last merge for this Phi.
          // So far, Phis have had a reasonable type from ciTypeFlow.
          // Now _gvn will join that with the meet of current inputs.
          // BOTTOM is never permissible here, 'cause pessimistically
          // Phis of pointers cannot lose the basic pointer type.
          debug_only(const Type* bt1 = phi->bottom_type());
          assert(bt1 != Type::BOTTOM, "should not be building conflict phis");
          map()->set_req(j, _gvn.transform_no_reclaim(phi));
          debug_only(const Type* bt2 = phi->bottom_type());
          assert(bt2->higher_equal_speculative(bt1), "must be consistent with type-flow");
          record_for_igvn(phi);
        }
      }
    } // End of for all values to be merged

    if (pnum == PhiNode::Input &&
        !r->in(0)) {         // The occasional useless Region
      assert(control() == r, "");
      set_control(r->nonnull_req());
    }

    map()->merge_replaced_nodes_with(newin);

    // newin has been subsumed into the lazy merge, and is now dead.
    set_block(save_block);

    stop();                     // done with this guy, for now
  }

  if (TraceOptoParse) {
    tty->print_cr(" on path %d", pnum);
  }

  // Done with this parser state.
  assert(stopped(), "");
}


//--------------------------merge_memory_edges---------------------------------
void Parse::merge_memory_edges(MergeMemNode* n, int pnum, bool nophi) {
  // (nophi means we must not create phis, because we already parsed here)
  assert(n != NULL, "");
  // Merge the inputs to the MergeMems
  MergeMemNode* m = merged_memory();

  assert(control()->is_Region(), "must be merging to a region");
  RegionNode* r = control()->as_Region();

  PhiNode* base = NULL;
  MergeMemNode* remerge = NULL;
  for (MergeMemStream mms(m, n); mms.next_non_empty2(); ) {
    Node *p = mms.force_memory();
    Node *q = mms.memory2();
    if (mms.is_empty() && nophi) {
      // Trouble:  No new splits allowed after a loop body is parsed.
      // Instead, wire the new split into a MergeMem on the backedge.
      // The optimizer will sort it out, slicing the phi.
      if (remerge == NULL) {
        assert(base != NULL, "");
        assert(base->in(0) != NULL, "should not be xformed away");
        remerge = MergeMemNode::make(C, base->in(pnum));
        gvn().set_type(remerge, Type::MEMORY);
        base->set_req(pnum, remerge);
      }
      remerge->set_memory_at(mms.alias_idx(), q);
      continue;
    }
    assert(!q->is_MergeMem(), "");
    PhiNode* phi;
    if (p != q) {
      phi = ensure_memory_phi(mms.alias_idx(), nophi);
    } else {
      if (p->is_Phi() && p->as_Phi()->region() == r)
        phi = p->as_Phi();
      else
        phi = NULL;
    }
    // Insert q into local phi
    if (phi != NULL) {
      assert(phi->region() == r, "");
      p = phi;
      phi->set_req(pnum, q);
      if (mms.at_base_memory()) {
        base = phi;  // delay transforming it
      } else if (pnum == 1) {
        record_for_igvn(phi);
        p = _gvn.transform_no_reclaim(phi);
      }
      mms.set_memory(p);// store back through the iterator
    }
  }
  // Transform base last, in case we must fiddle with remerging.
  if (base != NULL && pnum == 1) {
    record_for_igvn(base);
    m->set_base_memory( _gvn.transform_no_reclaim(base) );
  }
}


//------------------------ensure_phis_everywhere-------------------------------
void Parse::ensure_phis_everywhere() {
  ensure_phi(TypeFunc::I_O);

  // Ensure a phi on all currently known memories.
  for (MergeMemStream mms(merged_memory()); mms.next_non_empty(); ) {
    ensure_memory_phi(mms.alias_idx());
    debug_only(mms.set_memory());  // keep the iterator happy
  }

  // Note:  This is our only chance to create phis for memory slices.
  // If we miss a slice that crops up later, it will have to be
  // merged into the base-memory phi that we are building here.
  // Later, the optimizer will comb out the knot, and build separate
  // phi-loops for each memory slice that matters.

  // Monitors must nest nicely and not get confused amongst themselves.
  // Phi-ify everything up to the monitors, though.
  uint monoff = map()->jvms()->monoff();
  uint nof_monitors = map()->jvms()->nof_monitors();

  assert(TypeFunc::Parms == map()->jvms()->locoff(), "parser map should contain only youngest jvms");
  bool check_elide_phi = block()->is_SEL_head();
  for (uint i = TypeFunc::Parms; i < monoff; i++) {
    if (!check_elide_phi || !block()->can_elide_SEL_phi(i)) {
      ensure_phi(i);
    }
  }

  // Even monitors need Phis, though they are well-structured.
  // This is true for OSR methods, and also for the rare cases where
  // a monitor object is the subject of a replace_in_map operation.
  // See bugs 4426707 and 5043395.
  for (uint m = 0; m < nof_monitors; m++) {
    ensure_phi(map()->jvms()->monitor_obj_offset(m));
  }
}


//-----------------------------add_new_path------------------------------------
// Add a previously unaccounted predecessor to this block.
int Parse::Block::add_new_path() {
  // If there is no map, return the lowest unused path number.
  if (!is_merged())  return pred_count()+1;  // there will be a map shortly

  SafePointNode* map = start_map();
  if (!map->control()->is_Region())
    return pred_count()+1;  // there may be a region some day
  RegionNode* r = map->control()->as_Region();

  // Add new path to the region.
  uint pnum = r->req();
  r->add_req(NULL);

  for (uint i = 1; i < map->req(); i++) {
    Node* n = map->in(i);
    if (i == TypeFunc::Memory) {
      // Ensure a phi on all currently known memories.
      for (MergeMemStream mms(n->as_MergeMem()); mms.next_non_empty(); ) {
        Node* phi = mms.memory();
        if (phi->is_Phi() && phi->as_Phi()->region() == r) {
          assert(phi->req() == pnum, "must be same size as region");
          phi->add_req(NULL);
        }
      }
    } else {
      if (n->is_Phi() && n->as_Phi()->region() == r) {
        assert(n->req() == pnum, "must be same size as region");
        n->add_req(NULL);
      }
    }
  }

  return pnum;
}

//------------------------------ensure_phi-------------------------------------
// Turn the idx'th entry of the current map into a Phi
PhiNode *Parse::ensure_phi(int idx, bool nocreate) {
  SafePointNode* map = this->map();
  Node* region = map->control();
  assert(region->is_Region(), "");

  Node* o = map->in(idx);
  assert(o != NULL, "");

  if (o == top())  return NULL; // TOP always merges into TOP

  if (o->is_Phi() && o->as_Phi()->region() == region) {
    return o->as_Phi();
  }

  // Now use a Phi here for merging
  assert(!nocreate, "Cannot build a phi for a block already parsed.");
  const JVMState* jvms = map->jvms();
  const Type* t = NULL;
  if (jvms->is_loc(idx)) {
    t = block()->local_type_at(idx - jvms->locoff());
  } else if (jvms->is_stk(idx)) {
    t = block()->stack_type_at(idx - jvms->stkoff());
  } else if (jvms->is_mon(idx)) {
    assert(!jvms->is_monitor_box(idx), "no phis for boxes");
    t = TypeInstPtr::BOTTOM; // this is sufficient for a lock object
  } else if ((uint)idx < TypeFunc::Parms) {
    t = o->bottom_type();  // Type::RETURN_ADDRESS or such-like.
  } else {
    assert(false, "no type information for this phi");
  }

  // If the type falls to bottom, then this must be a local that
  // is mixing ints and oops or some such.  Forcing it to top
  // makes it go dead.
  if (t == Type::BOTTOM) {
    map->set_req(idx, top());
    return NULL;
  }

  // Do not create phis for top either.
  // A top on a non-null control flow must be an unused even after the.phi.
  if (t == Type::TOP || t == Type::HALF) {
    map->set_req(idx, top());
    return NULL;
  }

  PhiNode* phi = PhiNode::make(region, o, t);
  gvn().set_type(phi, t);
  if (C->do_escape_analysis()) record_for_igvn(phi);
  map->set_req(idx, phi);
  return phi;
}

//--------------------------ensure_memory_phi----------------------------------
// Turn the idx'th slice of the current memory into a Phi
PhiNode *Parse::ensure_memory_phi(int idx, bool nocreate) {
  MergeMemNode* mem = merged_memory();
  Node* region = control();
  assert(region->is_Region(), "");

  Node *o = (idx == Compile::AliasIdxBot)? mem->base_memory(): mem->memory_at(idx);
  assert(o != NULL && o != top(), "");

  PhiNode* phi;
  if (o->is_Phi() && o->as_Phi()->region() == region) {
    phi = o->as_Phi();
    if (phi == mem->base_memory() && idx >= Compile::AliasIdxRaw) {
      // clone the shared base memory phi to make a new memory split
      assert(!nocreate, "Cannot build a phi for a block already parsed.");
      const Type* t = phi->bottom_type();
      const TypePtr* adr_type = C->get_adr_type(idx);
      phi = phi->slice_memory(adr_type);
      gvn().set_type(phi, t);
    }
    return phi;
  }

  // Now use a Phi here for merging
  assert(!nocreate, "Cannot build a phi for a block already parsed.");
  const Type* t = o->bottom_type();
  const TypePtr* adr_type = C->get_adr_type(idx);
  phi = PhiNode::make(region, o, t, adr_type);
  gvn().set_type(phi, t);
  if (idx == Compile::AliasIdxBot)
    mem->set_base_memory(phi);
  else
    mem->set_memory_at(idx, phi);
  return phi;
}

//------------------------------call_register_finalizer-----------------------
// Check the klass of the receiver and call register_finalizer if the
// class need finalization.
void Parse::call_register_finalizer() {
  Node* receiver = local(0);
  assert(receiver != NULL && receiver->bottom_type()->isa_instptr() != NULL,
         "must have non-null instance type");

  const TypeInstPtr *tinst = receiver->bottom_type()->isa_instptr();
  if (tinst != NULL && tinst->klass()->is_loaded() && !tinst->klass_is_exact()) {
    // The type isn't known exactly so see if CHA tells us anything.
    ciInstanceKlass* ik = tinst->klass()->as_instance_klass();
    if (!Dependencies::has_finalizable_subclass(ik)) {
      // No finalizable subclasses so skip the dynamic check.
      C->dependencies()->assert_has_no_finalizable_subclasses(ik);
      return;
    }
  }

  // Insert a dynamic test for whether the instance needs
  // finalization.  In general this will fold up since the concrete
  // class is often visible so the access flags are constant.
  Node* klass_addr = basic_plus_adr( receiver, receiver, oopDesc::klass_offset_in_bytes() );
  Node* klass = _gvn.transform(LoadKlassNode::make(_gvn, NULL, immutable_memory(), klass_addr, TypeInstPtr::KLASS));

  Node* access_flags_addr = basic_plus_adr(klass, klass, in_bytes(Klass::access_flags_offset()));
  Node* access_flags = make_load(NULL, access_flags_addr, TypeInt::INT, T_INT, MemNode::unordered);

  Node* mask  = _gvn.transform(new (C) AndINode(access_flags, intcon(JVM_ACC_HAS_FINALIZER)));
  Node* check = _gvn.transform(new (C) CmpINode(mask, intcon(0)));
  Node* test  = _gvn.transform(new (C) BoolNode(check, BoolTest::ne));

  IfNode* iff = create_and_map_if(control(), test, PROB_MAX, COUNT_UNKNOWN);

  RegionNode* result_rgn = new (C) RegionNode(3);
  record_for_igvn(result_rgn);

  Node *skip_register = _gvn.transform(new (C) IfFalseNode(iff));
  result_rgn->init_req(1, skip_register);

  Node *needs_register = _gvn.transform(new (C) IfTrueNode(iff));
  set_control(needs_register);
  if (stopped()) {
    // There is no slow path.
    result_rgn->init_req(2, top());
  } else {
    Node *call = make_runtime_call(RC_NO_LEAF,
                                   OptoRuntime::register_finalizer_Type(),
                                   OptoRuntime::register_finalizer_Java(),
                                   NULL, TypePtr::BOTTOM,
                                   receiver);
    make_slow_call_ex(call, env()->Throwable_klass(), true);

    Node* fast_io  = call->in(TypeFunc::I_O);
    Node* fast_mem = call->in(TypeFunc::Memory);
    // These two phis are pre-filled with copies of of the fast IO and Memory
    Node* io_phi   = PhiNode::make(result_rgn, fast_io,  Type::ABIO);
    Node* mem_phi  = PhiNode::make(result_rgn, fast_mem, Type::MEMORY, TypePtr::BOTTOM);

    result_rgn->init_req(2, control());
    io_phi    ->init_req(2, i_o());
    mem_phi   ->init_req(2, reset_memory());

    set_all_memory( _gvn.transform(mem_phi) );
    set_i_o(        _gvn.transform(io_phi) );
  }

  set_control( _gvn.transform(result_rgn) );
}

// Add check to deoptimize if RTM state is not ProfileRTM
void Parse::rtm_deopt() {
#if INCLUDE_RTM_OPT
  if (C->profile_rtm()) {
    assert(C->method() != NULL, "only for normal compilations");
    assert(!C->method()->method_data()->is_empty(), "MDO is needed to record RTM state");
    assert(depth() == 1, "generate check only for main compiled method");

    // Set starting bci for uncommon trap.
    set_parse_bci(is_osr_parse() ? osr_bci() : 0);

    // Load the rtm_state from the MethodData.
    const TypePtr* adr_type = TypeMetadataPtr::make(C->method()->method_data());
    Node* mdo = makecon(adr_type);
    int offset = MethodData::rtm_state_offset_in_bytes();
    Node* adr_node = basic_plus_adr(mdo, mdo, offset);
    Node* rtm_state = make_load(control(), adr_node, TypeInt::INT, T_INT, adr_type, MemNode::unordered);

    // Separate Load from Cmp by Opaque.
    // In expand_macro_nodes() it will be replaced either
    // with this load when there are locks in the code
    // or with ProfileRTM (cmp->in(2)) otherwise so that
    // the check will fold.
    Node* profile_state = makecon(TypeInt::make(ProfileRTM));
    Node* opq   = _gvn.transform( new (C) Opaque3Node(C, rtm_state, Opaque3Node::RTM_OPT) );
    Node* chk   = _gvn.transform( new (C) CmpINode(opq, profile_state) );
    Node* tst   = _gvn.transform( new (C) BoolNode(chk, BoolTest::eq) );
    // Branch to failure if state was changed
    { BuildCutout unless(this, tst, PROB_ALWAYS);
      uncommon_trap(Deoptimization::Reason_rtm_state_change,
                    Deoptimization::Action_make_not_entrant);
    }
  }
#endif
}

//------------------------------return_current---------------------------------
// Append current _map to _exit_return
void Parse::return_current(Node* value) {
  if (RegisterFinalizersAtInit &&
      method()->intrinsic_id() == vmIntrinsics::_Object_init) {
    call_register_finalizer();
  }

  // Do not set_parse_bci, so that return goo is credited to the return insn.
  set_bci(InvocationEntryBci);
  if (method()->is_synchronized() && GenerateSynchronizationCode) {
    shared_unlock(_synch_lock->box_node(), _synch_lock->obj_node());
  }
  if (C->env()->dtrace_method_probes()) {
    make_dtrace_method_exit(method());
  }
  SafePointNode* exit_return = _exits.map();
  exit_return->in( TypeFunc::Control  )->add_req( control() );
  exit_return->in( TypeFunc::I_O      )->add_req( i_o    () );
  Node *mem = exit_return->in( TypeFunc::Memory   );
  for (MergeMemStream mms(mem->as_MergeMem(), merged_memory()); mms.next_non_empty2(); ) {
    if (mms.is_empty()) {
      // get a copy of the base memory, and patch just this one input
      const TypePtr* adr_type = mms.adr_type(C);
      Node* phi = mms.force_memory()->as_Phi()->slice_memory(adr_type);
      assert(phi->as_Phi()->region() == mms.base_memory()->in(0), "");
      gvn().set_type_bottom(phi);
      phi->del_req(phi->req()-1);  // prepare to re-patch
      mms.set_memory(phi);
    }
    mms.memory()->add_req(mms.memory2());
  }

  // frame pointer is always same, already captured
  if (value != NULL) {
    // If returning oops to an interface-return, there is a silent free
    // cast from oop to interface allowed by the Verifier.  Make it explicit
    // here.
    Node* phi = _exits.argument(0);
    const TypeInstPtr *tr = phi->bottom_type()->isa_instptr();
    if (tr && tr->klass()->is_loaded() &&
        tr->klass()->is_interface()) {
      const TypeInstPtr *tp = value->bottom_type()->isa_instptr();
      if (tp && tp->klass()->is_loaded() &&
          !tp->klass()->is_interface()) {
        // sharpen the type eagerly; this eases certain assert checking
        if (tp->higher_equal(TypeInstPtr::NOTNULL))
          tr = tr->join_speculative(TypeInstPtr::NOTNULL)->is_instptr();
        value = _gvn.transform(new (C) CheckCastPPNode(0, value, tr));
      }
    } else {
      // Also handle returns of oop-arrays to an arrays-of-interface return
      const TypeInstPtr* phi_tip;
      const TypeInstPtr* val_tip;
      Type::get_arrays_base_elements(phi->bottom_type(), value->bottom_type(), &phi_tip, &val_tip);
      if (phi_tip != NULL && phi_tip->is_loaded() && phi_tip->klass()->is_interface() &&
          val_tip != NULL && val_tip->is_loaded() && !val_tip->klass()->is_interface()) {
         value = _gvn.transform(new (C) CheckCastPPNode(0, value, phi->bottom_type()));
      }
    }
    phi->add_req(value);
  }

  if (_first_return) {
    _exits.map()->transfer_replaced_nodes_from(map(), _new_idx);
    _first_return = false;
  } else {
    _exits.map()->merge_replaced_nodes_with(map());
  }

  stop_and_kill_map();          // This CFG path dies here
}


//------------------------------add_safepoint----------------------------------
void Parse::add_safepoint() {
  // See if we can avoid this safepoint.  No need for a SafePoint immediately
  // after a Call (except Leaf Call) or another SafePoint.
  Node *proj = control();
  bool add_poll_param = SafePointNode::needs_polling_address_input();
  uint parms = add_poll_param ? TypeFunc::Parms+1 : TypeFunc::Parms;
  if( proj->is_Proj() ) {
    Node *n0 = proj->in(0);
    if( n0->is_Catch() ) {
      n0 = n0->in(0)->in(0);
      assert( n0->is_Call(), "expect a call here" );
    }
    if( n0->is_Call() ) {
      if( n0->as_Call()->guaranteed_safepoint() )
        return;
    } else if( n0->is_SafePoint() && n0->req() >= parms ) {
      return;
    }
  }

  // Clear out dead values from the debug info.
  kill_dead_locals();

  // Clone the JVM State
  SafePointNode *sfpnt = new (C) SafePointNode(parms, NULL);

  // Capture memory state BEFORE a SafePoint.  Since we can block at a
  // SafePoint we need our GC state to be safe; i.e. we need all our current
  // write barriers (card marks) to not float down after the SafePoint so we
  // must read raw memory.  Likewise we need all oop stores to match the card
  // marks.  If deopt can happen, we need ALL stores (we need the correct JVM
  // state on a deopt).

  // We do not need to WRITE the memory state after a SafePoint.  The control
  // edge will keep card-marks and oop-stores from floating up from below a
  // SafePoint and our true dependency added here will keep them from floating
  // down below a SafePoint.

  // Clone the current memory state
  Node* mem = MergeMemNode::make(C, map()->memory());

  mem = _gvn.transform(mem);

  // Pass control through the safepoint
  sfpnt->init_req(TypeFunc::Control  , control());
  // Fix edges normally used by a call
  sfpnt->init_req(TypeFunc::I_O      , top() );
  sfpnt->init_req(TypeFunc::Memory   , mem   );
  sfpnt->init_req(TypeFunc::ReturnAdr, top() );
  sfpnt->init_req(TypeFunc::FramePtr , top() );

  // Create a node for the polling address
  if( add_poll_param ) {
    Node *polladr = ConPNode::make(C, (address)os::get_polling_page());
    sfpnt->init_req(TypeFunc::Parms+0, _gvn.transform(polladr));
  }

  // Fix up the JVM State edges
  add_safepoint_edges(sfpnt);
  Node *transformed_sfpnt = _gvn.transform(sfpnt);
  set_control(transformed_sfpnt);

  // Provide an edge from root to safepoint.  This makes the safepoint
  // appear useful until the parse has completed.
  if( OptoRemoveUseless && transformed_sfpnt->is_SafePoint() ) {
    assert(C->root() != NULL, "Expect parse is still valid");
    C->root()->add_prec(transformed_sfpnt);
  }
}

#ifndef PRODUCT
//------------------------show_parse_info--------------------------------------
void Parse::show_parse_info() {
  InlineTree* ilt = NULL;
  if (C->ilt() != NULL) {
    JVMState* caller_jvms = is_osr_parse() ? caller()->caller() : caller();
    ilt = InlineTree::find_subtree_from_root(C->ilt(), caller_jvms, method());
  }
  if (PrintCompilation && Verbose) {
    if (depth() == 1) {
      if( ilt->count_inlines() ) {
        tty->print("    __inlined %d (%d bytes)", ilt->count_inlines(),
                     ilt->count_inline_bcs());
        tty->cr();
      }
    } else {
      if (method()->is_synchronized())         tty->print("s");
      if (method()->has_exception_handlers())  tty->print("!");
      // Check this is not the final compiled version
      if (C->trap_can_recompile()) {
        tty->print("-");
      } else {
        tty->print(" ");
      }
      method()->print_short_name();
      if (is_osr_parse()) {
        tty->print(" @ %d", osr_bci());
      }
      tty->print(" (%d bytes)",method()->code_size());
      if (ilt->count_inlines()) {
        tty->print(" __inlined %d (%d bytes)", ilt->count_inlines(),
                   ilt->count_inline_bcs());
      }
      tty->cr();
    }
  }
  if (PrintOpto && (depth() == 1 || PrintOptoInlining)) {
    // Print that we succeeded; suppress this message on the first osr parse.

    if (method()->is_synchronized())         tty->print("s");
    if (method()->has_exception_handlers())  tty->print("!");
    // Check this is not the final compiled version
    if (C->trap_can_recompile() && depth() == 1) {
      tty->print("-");
    } else {
      tty->print(" ");
    }
    if( depth() != 1 ) { tty->print("   "); }  // missing compile count
    for (int i = 1; i < depth(); ++i) { tty->print("  "); }
    method()->print_short_name();
    if (is_osr_parse()) {
      tty->print(" @ %d", osr_bci());
    }
    if (ilt->caller_bci() != -1) {
      tty->print(" @ %d", ilt->caller_bci());
    }
    tty->print(" (%d bytes)",method()->code_size());
    if (ilt->count_inlines()) {
      tty->print(" __inlined %d (%d bytes)", ilt->count_inlines(),
                 ilt->count_inline_bcs());
    }
    tty->cr();
  }
}


//------------------------------dump-------------------------------------------
// Dump information associated with the bytecodes of current _method
void Parse::dump() {
  if( method() != NULL ) {
    // Iterate over bytecodes
    ciBytecodeStream iter(method());
    for( Bytecodes::Code bc = iter.next(); bc != ciBytecodeStream::EOBC() ; bc = iter.next() ) {
      dump_bci( iter.cur_bci() );
      tty->cr();
    }
  }
}

// Dump information associated with a byte code index, 'bci'
void Parse::dump_bci(int bci) {
  // Output info on merge-points, cloning, and within _jsr..._ret
  // NYI
  tty->print(" bci:%d", bci);
}

#endif