01: /* Copyright (C) 2004 - 2007 db4objects Inc. http://www.db4o.com
02:
03: This file is part of the db4o open source object database.
04:
05: db4o is free software; you can redistribute it and/or modify it under
06: the terms of version 2 of the GNU General Public License as published
07: by the Free Software Foundation and as clarified by db4objects' GPL
08: interpretation policy, available at
09: http://www.db4o.com/about/company/legalpolicies/gplinterpretation/
10: Alternatively you can write to db4objects, Inc., 1900 S Norfolk Street,
11: Suite 350, San Mateo, CA 94403, USA.
12:
13: db4o is distributed in the hope that it will be useful, but WITHOUT ANY
14: WARRANTY; without even the implied warranty of MERCHANTABILITY or
15: FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
16: for more details.
17:
18: You should have received a copy of the GNU General Public License along
19: with this program; if not, write to the Free Software Foundation, Inc.,
20: 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
21: package EDU.purdue.cs.bloat.tree;
22:
23: import java.util.*;
24:
25: /**
26: * A PhiStmt is inserted into a CFG in Single Static Assignment for. It is used
27: * to "merge" uses of the same variable in different basic blocks.
28: *
29: * @see PhiJoinStmt
30: * @see PhiCatchStmt
31: */
32: public abstract class PhiStmt extends Stmt implements Assign {
33: VarExpr target; // The variable into which the Phi statement assigns
34:
35: /**
36: * Constructor.
37: *
38: * @param target
39: * A stack expression or local variable that is the target of
40: * this phi-statement.
41: */
42: public PhiStmt(final VarExpr target) {
43: this .target = target;
44: target.setParent(this );
45: }
46:
47: public VarExpr target() {
48: return target;
49: }
50:
51: /**
52: * Return the expressions (variables) defined by this PhiStmt. In this case,
53: * only the target is defined.
54: */
55: public DefExpr[] defs() {
56: return new DefExpr[] { target };
57: }
58:
59: public abstract Collection operands();
60:
61: public Object clone() {
62: throw new RuntimeException();
63: }
64: }
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