view hotspot/src/share/vm/opto/rootnode.cpp @ 3904:007a45522a7f

6877254: Server vm crashes with no branches off of store slice" when run with CMS and UseSuperWord(default) Summary: design StoreCMNode::Ideal to promote its oopStore input if the input is a MergeMem node Reviewed-by: kvn, never
author cfang
date Mon, 14 Sep 2009 09:49:54 -0700
children f4b087cbb361
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 * Copyright 1997-2005 Sun Microsystems, Inc.  All Rights Reserved.
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
 * CA 95054 USA or visit if you need additional information or
 * have any questions.

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

// Remove dead inputs
Node *RootNode::Ideal(PhaseGVN *phase, bool can_reshape) {
  for( uint i = 1; i < req(); i++ ) { // For all inputs
    // Check for and remove dead inputs
    if( phase->type(in(i)) == Type::TOP ) {
      del_req(i--);             // Delete TOP inputs

  // I used to do tail-splitting in the Ideal graph here, but it does not
  // work.  The tail-splitting forces values live into the Return to be
  // ready at a point which dominates the split returns.  This forces Stores
  // to be hoisted high.  The "proper" fix would be to split Stores down
  // each path, but this makes the split unprofitable.  If we want to do this
  // optimization, it needs to be done after allocation so we can count all
  // the instructions needing to be cloned in the cost metric.

  // There used to be a spoof here for caffeine marks which completely
  // eliminated very simple self-recursion recursions, but it's not worth it.
  // Deep inlining of self-calls gets nearly all of the same benefits.
  // If we want to get the rest of the win later, we should pattern match
  // simple recursive call trees to closed-form solutions.

  return NULL;                  // No further opportunities exposed

HaltNode::HaltNode( Node *ctrl, Node *frameptr ) : Node(TypeFunc::Parms) {
  Node* top = Compile::current()->top();
  init_req(TypeFunc::Control,  ctrl        );
  init_req(TypeFunc::I_O,      top);
  init_req(TypeFunc::Memory,   top);
  init_req(TypeFunc::FramePtr, frameptr    );

const Type *HaltNode::bottom_type() const { return Type::BOTTOM; }

Node *HaltNode::Ideal(PhaseGVN *phase, bool can_reshape) {
  return remove_dead_region(phase, can_reshape) ? this : NULL;

const Type *HaltNode::Value( PhaseTransform *phase ) const {
  return ( phase->type(in(TypeFunc::Control)) == Type::TOP)
    ? Type::TOP
    : Type::BOTTOM;

const RegMask &HaltNode::out_RegMask() const {
  return RegMask::Empty;