1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/src/share/vm/opto/rootnode.cpp Wed Apr 27 01:25:04 2016 +0800
1.3 @@ -0,0 +1,88 @@
1.4 +/*
1.5 + * Copyright (c) 1997, 2010, Oracle and/or its affiliates. All rights reserved.
1.6 + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
1.7 + *
1.8 + * This code is free software; you can redistribute it and/or modify it
1.9 + * under the terms of the GNU General Public License version 2 only, as
1.10 + * published by the Free Software Foundation.
1.11 + *
1.12 + * This code is distributed in the hope that it will be useful, but WITHOUT
1.13 + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
1.14 + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
1.15 + * version 2 for more details (a copy is included in the LICENSE file that
1.16 + * accompanied this code).
1.17 + *
1.18 + * You should have received a copy of the GNU General Public License version
1.19 + * 2 along with this work; if not, write to the Free Software Foundation,
1.20 + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
1.21 + *
1.22 + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
1.23 + * or visit www.oracle.com if you need additional information or have any
1.24 + * questions.
1.25 + *
1.26 + */
1.27 +
1.28 +#include "precompiled.hpp"
1.29 +#include "memory/allocation.inline.hpp"
1.30 +#include "opto/callnode.hpp"
1.31 +#include "opto/cfgnode.hpp"
1.32 +#include "opto/phaseX.hpp"
1.33 +#include "opto/regmask.hpp"
1.34 +#include "opto/rootnode.hpp"
1.35 +#include "opto/subnode.hpp"
1.36 +#include "opto/type.hpp"
1.37 +
1.38 +//------------------------------Ideal------------------------------------------
1.39 +// Remove dead inputs
1.40 +Node *RootNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1.41 + for( uint i = 1; i < req(); i++ ) { // For all inputs
1.42 + // Check for and remove dead inputs
1.43 + if( phase->type(in(i)) == Type::TOP ) {
1.44 + del_req(i--); // Delete TOP inputs
1.45 + }
1.46 + }
1.47 +
1.48 + // I used to do tail-splitting in the Ideal graph here, but it does not
1.49 + // work. The tail-splitting forces values live into the Return to be
1.50 + // ready at a point which dominates the split returns. This forces Stores
1.51 + // to be hoisted high. The "proper" fix would be to split Stores down
1.52 + // each path, but this makes the split unprofitable. If we want to do this
1.53 + // optimization, it needs to be done after allocation so we can count all
1.54 + // the instructions needing to be cloned in the cost metric.
1.55 +
1.56 + // There used to be a spoof here for caffeine marks which completely
1.57 + // eliminated very simple self-recursion recursions, but it's not worth it.
1.58 + // Deep inlining of self-calls gets nearly all of the same benefits.
1.59 + // If we want to get the rest of the win later, we should pattern match
1.60 + // simple recursive call trees to closed-form solutions.
1.61 +
1.62 + return NULL; // No further opportunities exposed
1.63 +}
1.64 +
1.65 +//=============================================================================
1.66 +HaltNode::HaltNode( Node *ctrl, Node *frameptr ) : Node(TypeFunc::Parms) {
1.67 + Node* top = Compile::current()->top();
1.68 + init_req(TypeFunc::Control, ctrl );
1.69 + init_req(TypeFunc::I_O, top);
1.70 + init_req(TypeFunc::Memory, top);
1.71 + init_req(TypeFunc::FramePtr, frameptr );
1.72 + init_req(TypeFunc::ReturnAdr,top);
1.73 +}
1.74 +
1.75 +const Type *HaltNode::bottom_type() const { return Type::BOTTOM; }
1.76 +
1.77 +//------------------------------Ideal------------------------------------------
1.78 +Node *HaltNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1.79 + return remove_dead_region(phase, can_reshape) ? this : NULL;
1.80 +}
1.81 +
1.82 +//------------------------------Value------------------------------------------
1.83 +const Type *HaltNode::Value( PhaseTransform *phase ) const {
1.84 + return ( phase->type(in(TypeFunc::Control)) == Type::TOP)
1.85 + ? Type::TOP
1.86 + : Type::BOTTOM;
1.87 +}
1.88 +
1.89 +const RegMask &HaltNode::out_RegMask() const {
1.90 + return RegMask::Empty;
1.91 +}
