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
54 // eliminated very simple self-recursion recursions, but it's not worth it.
55 // Deep inlining of self-calls gets nearly all of the same benefits.
56 // If we want to get the rest of the win later, we should pattern match
57 // simple recursive call trees to closed-form solutions.
58
59 return NULL; // No further opportunities exposed
60 }
61
62 //=============================================================================
63 HaltNode::HaltNode( Node *ctrl, Node *frameptr ) : Node(TypeFunc::Parms) {
64 Node* top = Compile::current()->top();
65 init_req(TypeFunc::Control, ctrl );
66 init_req(TypeFunc::I_O, top);
67 init_req(TypeFunc::Memory, top);
68 init_req(TypeFunc::FramePtr, frameptr );
69 init_req(TypeFunc::ReturnAdr,top);
70 }
71
72 const Type *HaltNode::bottom_type() const { return Type::BOTTOM; }
73
74 //------------------------------Ideal------------------------------------------
75 Node *HaltNode::Ideal(PhaseGVN *phase, bool can_reshape) {
76 return remove_dead_region(phase, can_reshape) ? this : NULL;
77 }
78
79 //------------------------------Value------------------------------------------
80 const Type *HaltNode::Value( PhaseTransform *phase ) const {
81 return ( phase->type(in(TypeFunc::Control)) == Type::TOP)
82 ? Type::TOP
83 : Type::BOTTOM;
84 }
85
86 const RegMask &HaltNode::out_RegMask() const {
87 return RegMask::Empty;
88 }