1 /*
 2  * Copyright (c) 1997, 2023, 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 : nullptr;
62 }
63 
64 //=============================================================================
65 HaltNode::HaltNode(Node* ctrl, Node* frameptr, const char* halt_reason, bool reachable)
66                         : Node(TypeFunc::Parms), _halt_reason(halt_reason), _reachable(reachable) {
67   init_class_id(Class_Halt);
68   Node* top = Compile::current()->top();
69   init_req(TypeFunc::Control,  ctrl        );
70   init_req(TypeFunc::I_O,      top);
71   init_req(TypeFunc::Memory,   top);
72   init_req(TypeFunc::FramePtr, frameptr    );
73   init_req(TypeFunc::ReturnAdr,top);

74 }
75 
76 const Type *HaltNode::bottom_type() const { return Type::BOTTOM; }
77 uint HaltNode::size_of() const { return sizeof(*this); }
78 
79 //------------------------------Ideal------------------------------------------
80 Node *HaltNode::Ideal(PhaseGVN *phase, bool can_reshape) {
81   return remove_dead_region(phase, can_reshape) ? this : nullptr;
82 }
83 
84 //------------------------------Value------------------------------------------
85 const Type* HaltNode::Value(PhaseGVN* phase) const {
86   return ( phase->type(in(TypeFunc::Control)) == Type::TOP)
87     ? Type::TOP
88     : Type::BOTTOM;
89 }
90 
91 const RegMask &HaltNode::out_RegMask() const {
92   return RegMask::Empty;
93 }
--- EOF ---