C++ GrowableArray::at_grow方法代码示例

 // address of an element in _nodes.  Used when the element is to be modified
 PointsToNode *ptnode_adr(uint idx) {
   if ((uint)_nodes->length() <= idx) {
     // expand _nodes array
     PointsToNode dummy = _nodes->at_grow(idx);
   }
   return _nodes->adr_at(idx);
 }

//------------------------------schedule_local---------------------------------
// Topological sort within a block.  Someday become a real scheduler.
bool Block::schedule_local(Matcher &matcher, Block_Array &bbs,int *ready_cnt, VectorSet &next_call, GrowableArray<uint> &node_latency) {
  // Already "sorted" are the block start Node (as the first entry), and
  // the block-ending Node and any trailing control projections.  We leave
  // these alone.  PhiNodes and ParmNodes are made to follow the block start
  // Node.  Everything else gets topo-sorted.

#ifndef PRODUCT
    if (TraceOptoPipelining) {
      tty->print("# before schedule_local\n");
      for (uint i = 0;i < _nodes.size();i++) {
        tty->print("# ");
        _nodes[i]->fast_dump();
      }
      tty->print("\n");
    }
#endif

  // RootNode is already sorted
  if( _nodes.size() == 1 ) return true;

  // Move PhiNodes and ParmNodes from 1 to cnt up to the start
  uint node_cnt = end_idx();
  uint phi_cnt = 1;
  uint i;
  for( i = 1; i<node_cnt; i++ ) { // Scan for Phi
    Node *n = _nodes[i];
    if( n->is_Phi() ||          // Found a PhiNode or ParmNode
        (n->is_Proj()  && n->in(0) == head()) ) {
      // Move guy at 'phi_cnt' to the end; makes a hole at phi_cnt
      _nodes.map(i,_nodes[phi_cnt]);
      _nodes.map(phi_cnt++,n);  // swap Phi/Parm up front
    } else {                    // All others
      // Count block-local inputs to 'n'
      uint cnt = n->len();      // Input count
      uint local = 0;
      for( uint j=0; j<cnt; j++ ) {
        Node *m = n->in(j);
        if( m && bbs[m->_idx] == this && !m->is_top() )
          local++;              // One more block-local input
      }
      ready_cnt[n->_idx] = local; // Count em up

      // A few node types require changing a required edge to a precedence edge
      // before allocation.
      MachNode *m = n->is_Mach();
      if( UseConcMarkSweepGC ) {
        if( m && m->ideal_Opcode() == Op_StoreCM ) {
          // Note: Required edges with an index greater than oper_input_base
          // are not supported by the allocator.
          // Note2: Can only depend on unmatched edge being last,
          // can not depend on its absolute position.
          Node *oop_store = n->in(n->req() - 1);
          n->del_req(n->req() - 1);
          n->add_prec(oop_store);
          assert(bbs[oop_store->_idx]->_dom_depth <= this->_dom_depth, "oop_store must dominate card-mark");
        }
      }
      if( m && m->ideal_Opcode() == Op_MemBarAcquire ) {
        Node *x = n->in(TypeFunc::Parms);
        n->del_req(TypeFunc::Parms);
        n->add_prec(x);
      }
    }
  }
  for(uint i2=i; i2<_nodes.size(); i2++ ) // Trailing guys get zapped count
    ready_cnt[_nodes[i2]->_idx] = 0;

  // All the prescheduled guys do not hold back internal nodes
  uint i3;
  for(i3 = 0; i3<phi_cnt; i3++ ) {  // For all pre-scheduled
    Node *n = _nodes[i3];       // Get pre-scheduled
    for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
      Node* m = n->fast_out(j);
      if( bbs[m->_idx] ==this ) // Local-block user
        ready_cnt[m->_idx]--;   // Fix ready count
    }
  }

  // Make a worklist
  Node_List worklist;
  for(uint i4=i3; i4<node_cnt; i4++ ) {    // Put ready guys on worklist
    Node *m = _nodes[i4];    
    if( !ready_cnt[m->_idx] )   // Zero ready count?
      worklist.push(m);         // Then on to worklist!
  }

  // Warm up the 'next_call' heuristic bits
  needed_for_next_call(_nodes[0], next_call, bbs);

#ifndef PRODUCT
    if (TraceOptoPipelining) {
      for (uint j=0; j<_nodes.size(); j++) {
        Node     *n = _nodes[j];
        int     idx = n->_idx;
        tty->print("#   ready cnt:%3d  ", ready_cnt[idx]);
        tty->print("latency:%3d  ", node_latency.at_grow(idx));
        tty->print("%4d: %s\n", idx, n->Name());
      }
//.........这里部分代码省略.........

//.........这里部分代码省略.........
          Node *n = b->_nodes[k];
          if( n->check_for_anti_dependence() && 
              n->in(LoadNode::Memory) == mach->in(StoreNode::Memory) )
	    break;              // Found anti-dependent load
        }
        if( k < b->_nodes.size() )
          break;                // Found anti-dependent load
        // Make sure control does not do a merge (would have to check allpaths)
        if( b->num_preds() != 2 ) break;
        b = bbs[b->pred(1)->_idx]; // Move up to predecessor block
      }
      if( b != this ) continue;
    }

    // Make sure this memory op is not already being used for a NullCheck
    MachNode *e = mb->end()->is_Mach();
    if( e && e->is_MachNullCheck() && e->in(1) == mach )
      continue;                 // Already being used as a NULL check

    // Found a candidate!  Pick one with least dom depth - the highest 
    // in the dom tree should be closest to the null check.
    if( !best || 
        bbs[mach->_idx]->_dom_depth < bbs[best->_idx]->_dom_depth ) {
      best = mach;
      bidx = vidx;

    }
  }
  // No candidate!
  if( !best ) return;

  // ---- Found an implicit null check
  extern int implicit_null_checks;
  implicit_null_checks++;

  // Hoist the memory candidate up to the end of the test block.
  Block *old_block = bbs[best->_idx];
  old_block->find_remove(best);
  add_inst(best);
  bbs.map(best->_idx,this);

  // Move the control dependence
  if (best->in(0) && best->in(0) == old_block->_nodes[0])
    best->set_req(0, _nodes[0]);

  // Check for flag-killing projections that also need to be hoisted
  // Should be DU safe because no edge updates.
  for (DUIterator_Fast jmax, j = best->fast_outs(jmax); j < jmax; j++) {
    Node* n = best->fast_out(j);
    if( n->Opcode() == Op_MachProj ) {
      bbs[n->_idx]->find_remove(n);
      add_inst(n);
      bbs.map(n->_idx,this);
    }
  }

  // proj==Op_True --> ne test; proj==Op_False --> eq test.
  // One of two graph shapes got matched:
  //   (IfTrue  (If (Bool NE (CmpP ptr NULL))))
  //   (IfFalse (If (Bool EQ (CmpP ptr NULL))))
  // NULL checks are always branch-if-eq.  If we see a IfTrue projection
  // then we are replacing a 'ne' test with a 'eq' NULL check test.
  // We need to flip the projections to keep the same semantics.
  if( proj->Opcode() == Op_IfTrue ) {
    // Swap order of projections in basic block to swap branch targets
    Node *tmp1 = _nodes[end_idx()+1];
    Node *tmp2 = _nodes[end_idx()+2];
    _nodes.map(end_idx()+1, tmp2);
    _nodes.map(end_idx()+2, tmp1);    
    Node *tmp = new (1) Node(1);
    tmp1->replace_by(tmp);
    tmp2->replace_by(tmp1);
    tmp->replace_by(tmp2);
  }

  // Remove the existing null check; use a new implicit null check instead.
  // Since schedule-local needs precise def-use info, we need to correct
  // it as well.
  Node *old_tst = proj->in(0);
  MachNode *nul_chk = new MachNullCheckNode(old_tst->in(0),best,bidx);
  _nodes.map(end_idx(),nul_chk);
  bbs.map(nul_chk->_idx,this);
  // Redirect users of old_test to nul_chk
  for (DUIterator_Last i2min, i2 = old_tst->last_outs(i2min); i2 >= i2min; --i2)
    old_tst->last_out(i2)->set_req(0, nul_chk);
  // Clean-up any dead code
  for (uint i3 = 0; i3 < old_tst->req(); i3++)
    old_tst->set_req(i3, NULL);
  latency.at_put_grow(nul_chk->_idx, nul_chk->latency_from_uses(bbs, latency));
  latency.at_put_grow(best   ->_idx, best   ->latency_from_uses(bbs, latency));

#ifndef PRODUCT
  if (TraceOptoPipelining) {
    tty->print("# implicit_null_check: latency %4d for ", latency.at_grow(best->_idx));
    best->fast_dump();
    tty->print("# implicit_null_check: latency %4d for ", latency.at_grow(nul_chk->_idx));
    nul_chk->fast_dump();
  }
#endif
}

 bool hidden_alias(Node *n) {
   if (_collecting)
     return true;
   PointsToNode  ptn = _nodes->at_grow(n->_idx);
   return (ptn.escape_state() != PointsToNode::NoEscape) || ptn._hidden_alias;
 }