Mercurial > hg > truffle

comparison graal/Compiler/src/com/sun/c1x/ir/Phi.java @ 2507:9ec15d6914ca

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
Pull over of compiler from maxine repository.
author Thomas Wuerthinger <thomas@wuerthinger.net>
date Wed, 27 Apr 2011 11:43:22 +0200
parents
children
comparison
equal deleted inserted replaced
2506:4a3bf8a5bf41 2507:9ec15d6914ca
1 /*
2 * Copyright (c) 2009, 2011, 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 package com.sun.c1x.ir;
24
25 import com.sun.c1x.debug.*;
26 import com.sun.c1x.value.*;
27 import com.sun.cri.ci.*;
28
29 /**
30 * The {@code Phi} instruction represents the merging of dataflow
31 * in the instruction graph. It refers to a join block and a variable.
32 *
33 * @author Ben L. Titzer
34 */
35 public final class Phi extends Value {
36
37 private final BlockBegin block;
38 private final int index;
39
40 /**
41 * Create a new Phi for the specified join block and local variable (or operand stack) slot.
42 * @param kind the type of the variable
43 * @param block the join point
44 * @param index the index into the stack (if < 0) or local variables
45 */
46 public Phi(CiKind kind, BlockBegin block, int index) {
47 super(kind);
48 this.block = block;
49 this.index = index;
50 }
51
52 /**
53 * Get the join block for this phi.
54 * @return the join block of this phi
55 */
56 @Override
57 public BlockBegin block() {
58 return block;
59 }
60
61 /**
62 * Check whether this phi corresponds to a local variable.
63 * @return {@code true} if this phi refers to a local variable
64 */
65 public boolean isLocal() {
66 return index >= 0;
67 }
68
69 /**
70 * Check whether this phi corresponds to a stack location.
71 * @return {@code true} if this phi refers to a stack location
72 */
73 public boolean isOnStack() {
74 return index < 0;
75 }
76
77 /**
78 * Get the local index of this phi.
79 * @return the local index
80 */
81 public int localIndex() {
82 assert isLocal();
83 return index;
84 }
85
86 /**
87 * Get the stack index of this phi.
88 * @return the stack index of this phi
89 */
90 public int stackIndex() {
91 assert isOnStack();
92 return -(index + 1);
93 }
94
95 /**
96 * Get the instruction that produces the value associated with the i'th predecessor
97 * of the join block.
98 * @param i the index of the predecessor
99 * @return the instruction that produced the value in the i'th predecessor
100 */
101 public Value inputAt(int i) {
102 FrameState state;
103 if (block.isExceptionEntry()) {
104 state = block.exceptionHandlerStates().get(i);
105 } else {
106 state = block.predecessors().get(i).end().stateAfter();
107 }
108 return inputIn(state);
109 }
110
111 /**
112 * Gets the instruction that produces the value for this phi in the specified state.
113 * @param state the state to access
114 * @return the instruction producing the value
115 */
116 public Value inputIn(FrameState state) {
117 if (isLocal()) {
118 return state.localAt(localIndex());
119 } else {
120 return state.stackAt(stackIndex());
121 }
122 }
123
124 /**
125 * Get the number of inputs to this phi (i.e. the number of predecessors to the join block).
126 * @return the number of inputs in this phi
127 */
128 public int inputCount() {
129 if (block.isExceptionEntry()) {
130 return block.exceptionHandlerStates().size();
131 } else {
132 return block.predecessors().size();
133 }
134 }
135
136 @Override
137 public void accept(ValueVisitor v) {
138 v.visitPhi(this);
139 }
140
141 /**
142 * Make this phi illegal if types were not merged correctly.
143 */
144 public void makeDead() {
145 setFlag(Flag.PhiCannotSimplify);
146 setFlag(Flag.PhiDead);
147 }
148
149 @Override
150 public void print(LogStream out) {
151 out.print("phi function");
152 }
153 }