1 cananian 1.1.2.1 // Stm.java, created Wed Jan 13 21:14:57 1999 by cananian
2 cananian 1.1.2.10 // Copyright (C) 1998 C. Scott Ananian <cananian@alumni.princeton.edu>
3 cananian 1.1.2.10 // Licensed under the terms of the GNU GPL; see COPYING for details.
4 cananian 1.1.2.1 package harpoon.IR.Tree;
5 cananian 1.1.2.1
6 cananian 1.1.2.15 import harpoon.ClassFile.HCodeElement;
7 duncan 1.1.2.4 import harpoon.Temp.CloningTempMap;
8 duncan 1.1.2.8 import harpoon.Util.Util;
9 duncan 1.1.2.7
10 duncan 1.1.2.11 import java.util.ArrayList;
11 cananian 1.1.2.12 import java.util.Collections;
12 duncan 1.1.2.8 import java.util.List;
13 duncan 1.1.2.8 import java.util.ListIterator;
14 duncan 1.1.2.7 import java.util.Set;
15 duncan 1.1.2.11 import java.util.Stack;
16 duncan 1.1.2.4
17 cananian 1.1.2.1 /**
18 cananian 1.1.2.1 * <code>Stm</code> objects are statements which perform side effects and
19 cananian 1.1.2.1 * control flow.
20 cananian 1.1.2.1 *
21 cananian 1.1.2.1 * @author C. Scott Ananian <cananian@alumni.princeton.edu>, based on
22 cananian 1.1.2.1 * <i>Modern Compiler Implementation in Java</i> by Andrew Appel.
23 cananian 1.3 * @version $Id: Stm.java,v 1.3 2002/04/10 03:05:45 cananian Exp $
24 cananian 1.1.2.1 */
25 cananian 1.1.2.3 abstract public class Stm extends Tree {
26 cananian 1.1.2.15 protected Stm(TreeFactory tf, HCodeElement source, int arity) {
27 cananian 1.1.2.15 super(tf, source, arity);
28 duncan 1.1.2.7 }
29 cananian 1.1.2.3
30 cananian 1.1.2.1 /** Build an <code>Stm</code> of this type from the given list of
31 cananian 1.1.2.1 * subexpressions. */
32 cananian 1.1.2.15 public final Stm build(ExpList kids) { return build(this.tf, kids); }
33 duncan 1.1.2.9 abstract public Stm build(TreeFactory tf, ExpList kids);
34 duncan 1.1.2.13
35 duncan 1.1.2.8 /** Returns a tree-based representation of <code>list</code>.
36 duncan 1.1.2.8 *
37 duncan 1.1.2.8 * <br><b>Requires:</b> foreach element, <code>l</code>, of
38 duncan 1.1.2.9 * <code>list</code>,
39 duncan 1.1.2.9 * <code>(l != null) && (l instanceof Stm)</code>.
40 duncan 1.1.2.8 * <br><b>Modifies:</b>
41 duncan 1.1.2.8 * <br><b>Effects: </b> returns a tree-based representation of
42 duncan 1.1.2.8 * <code>list</code>. If <code>list</code> is null,
43 duncan 1.1.2.8 * returns null.
44 duncan 1.1.2.8 */
45 cananian 1.2.2.1 public static Stm toStm(List<Stm> list) {
46 duncan 1.1.2.8 if (list==null) return null;
47 duncan 1.1.2.8 int size = list.size();
48 duncan 1.1.2.8 if (size==0) { return null; }
49 cananian 1.2.2.1 else if (size==1) { return list.get(0); }
50 cananian 1.1.2.19 else { // divide and conquer
51 cananian 1.2.2.1 Stm hce = list.get(0);
52 duncan 1.1.2.8 TreeFactory tf = hce.getFactory();
53 cananian 1.1.2.19 return new SEQ(tf,hce,
54 cananian 1.1.2.19 toStm(list.subList(0,size/2)),
55 cananian 1.1.2.19 toStm(list.subList(size/2,list.size())));
56 duncan 1.1.2.8 }
57 duncan 1.1.2.11 }
58 duncan 1.1.2.11
59 duncan 1.1.2.11 /**
60 duncan 1.1.2.11 * Returns a <code>Stm</code> such that all <code>SEQ</code> objects
61 duncan 1.1.2.11 * contained within the <code>Stm</code> object are on the top level.
62 duncan 1.1.2.11 */
63 duncan 1.1.2.11 public static Stm linearize(Stm stm) {
64 duncan 1.1.2.11 List l = new ArrayList();
65 duncan 1.1.2.11 Stack s = new Stack();
66 duncan 1.1.2.11 s.push(stm);
67 duncan 1.1.2.11
68 duncan 1.1.2.11 while (!s.isEmpty()) {
69 duncan 1.1.2.11 Stm next = (Stm)s.pop();
70 duncan 1.1.2.11 if (next.kind() == TreeKind.SEQ) {
71 duncan 1.1.2.11 SEQ seq = (SEQ)next;
72 duncan 1.1.2.14 s.push(seq.getRight());
73 duncan 1.1.2.14 s.push(seq.getLeft());
74 duncan 1.1.2.11 }
75 duncan 1.1.2.11 else {
76 duncan 1.1.2.11 l.add(next);
77 duncan 1.1.2.11 }
78 duncan 1.1.2.11 }
79 duncan 1.1.2.11 return toStm(l);
80 duncan 1.1.2.11 }
81 duncan 1.1.2.11
82 duncan 1.1.2.11 /**
83 duncan 1.1.2.11 * Returns true if <code>stm</code> has no effect.
84 duncan 1.1.2.11 */
85 duncan 1.1.2.11 public static boolean isNop(Stm stm) {
86 jwhaley 1.1.2.18 return (stm.kind()==TreeKind.EXPR) &&
87 jwhaley 1.1.2.18 ((((EXPR)stm).getExp()).kind()==TreeKind.CONST);
88 duncan 1.1.2.8 }
89 cananian 1.1.2.1 }
90 cananian 1.2