1 /*
   2  * Copyright (c) 1997, 2015, 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   bool modified = false;
  39   for( uint i = 1; i < req(); i++ ) { // For all inputs
  40     // Check for and remove dead inputs
  41     if( phase->type(in(i)) == Type::TOP ) {
  42       del_req(i--);             // Delete TOP inputs
  43       modified = true;
  44     }
  45   }
  46 
  47   // I used to do tail-splitting in the Ideal graph here, but it does not
  48   // work.  The tail-splitting forces values live into the Return to be
  49   // ready at a point which dominates the split returns.  This forces Stores
  50   // to be hoisted high.  The "proper" fix would be to split Stores down
  51   // each path, but this makes the split unprofitable.  If we want to do this
  52   // optimization, it needs to be done after allocation so we can count all
  53   // the instructions needing to be cloned in the cost metric.
  54 
  55   // There used to be a spoof here for caffeine marks which completely
  56   // eliminated very simple self-recursion recursions, but it's not worth it.
  57   // Deep inlining of self-calls gets nearly all of the same benefits.
  58   // If we want to get the rest of the win later, we should pattern match
  59   // simple recursive call trees to closed-form solutions.
  60 
  61   return modified ? this : NULL;
  62 }
  63 
  64 //=============================================================================
  65 HaltNode::HaltNode( Node *ctrl, Node *frameptr ) : Node(TypeFunc::Parms) {
  66   Node* top = Compile::current()->top();
  67   init_req(TypeFunc::Control,  ctrl        );
  68   init_req(TypeFunc::I_O,      top);
  69   init_req(TypeFunc::Memory,   top);
  70   init_req(TypeFunc::FramePtr, frameptr    );
  71   init_req(TypeFunc::ReturnAdr,top);
  72 }
  73 
  74 const Type *HaltNode::bottom_type() const { return Type::BOTTOM; }
  75 
  76 //------------------------------Ideal------------------------------------------
  77 Node *HaltNode::Ideal(PhaseGVN *phase, bool can_reshape) {
  78   return remove_dead_region(phase, can_reshape) ? this : NULL;
  79 }
  80 
  81 //------------------------------Value------------------------------------------
  82 const Type *HaltNode::Value( PhaseTransform *phase ) const {
  83   return ( phase->type(in(TypeFunc::Control)) == Type::TOP)
  84     ? Type::TOP
  85     : Type::BOTTOM;
  86 }
  87 
  88 const RegMask &HaltNode::out_RegMask() const {
  89   return RegMask::Empty;
  90 }
  91 
  92 #ifndef PRODUCT
  93 //-------------------------------rel-------------------------------------------
  94 // Include all control inputs in the related set, and also the input data
  95 // boundary. In compact mode, include all inputs till level 2. Also include
  96 // all outputs at level 1.
  97 void HaltNode::rel(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const {
  98   if (compact) {
  99     this->collect_nodes(in_rel, 2, false, false);
 100   } else {
 101     this->collect_nodes_in_all_ctrl(in_rel, true);
 102   }
 103   this->collect_nodes(out_rel, -1, false, false);
 104 }
 105 #endif