1 /*
   2  * Copyright (c) 1997, 2005, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "incls/_precompiled.incl"
  26 #include "incls/_rootnode.cpp.incl"







  27 
  28 //------------------------------Ideal------------------------------------------
  29 // Remove dead inputs
  30 Node *RootNode::Ideal(PhaseGVN *phase, bool can_reshape) {
  31   for( uint i = 1; i < req(); i++ ) { // For all inputs
  32     // Check for and remove dead inputs
  33     if( phase->type(in(i)) == Type::TOP ) {
  34       del_req(i--);             // Delete TOP inputs
  35     }
  36   }
  37 
  38   // I used to do tail-splitting in the Ideal graph here, but it does not
  39   // work.  The tail-splitting forces values live into the Return to be
  40   // ready at a point which dominates the split returns.  This forces Stores
  41   // to be hoisted high.  The "proper" fix would be to split Stores down
  42   // each path, but this makes the split unprofitable.  If we want to do this
  43   // optimization, it needs to be done after allocation so we can count all
  44   // the instructions needing to be cloned in the cost metric.
  45 
  46   // There used to be a spoof here for caffeine marks which completely

   1 /*
   2  * Copyright (c) 1997, 2010, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "memory/allocation.inline.hpp"
  27 #include "opto/callnode.hpp"
  28 #include "opto/cfgnode.hpp"
  29 #include "opto/phaseX.hpp"
  30 #include "opto/regmask.hpp"
  31 #include "opto/rootnode.hpp"
  32 #include "opto/subnode.hpp"
  33 #include "opto/type.hpp"
  34 
  35 //------------------------------Ideal------------------------------------------
  36 // Remove dead inputs
  37 Node *RootNode::Ideal(PhaseGVN *phase, bool can_reshape) {
  38   for( uint i = 1; i < req(); i++ ) { // For all inputs
  39     // Check for and remove dead inputs
  40     if( phase->type(in(i)) == Type::TOP ) {
  41       del_req(i--);             // Delete TOP inputs
  42     }
  43   }
  44 
  45   // I used to do tail-splitting in the Ideal graph here, but it does not
  46   // work.  The tail-splitting forces values live into the Return to be
  47   // ready at a point which dominates the split returns.  This forces Stores
  48   // to be hoisted high.  The "proper" fix would be to split Stores down
  49   // each path, but this makes the split unprofitable.  If we want to do this
  50   // optimization, it needs to be done after allocation so we can count all
  51   // the instructions needing to be cloned in the cost metric.
  52 
  53   // There used to be a spoof here for caffeine marks which completely