1 cananian 1.1.2.1 // BitFieldNumbering.java, created Sun Mar 4 20:21:45 2001 by cananian
2 cananian 1.1.2.1 // Copyright (C) 2000 C. Scott Ananian <cananian@alumni.princeton.edu>
3 cananian 1.1.2.1 // Licensed under the terms of the GNU GPL; see COPYING for details.
4 cananian 1.1.2.1 package harpoon.Analysis.Transactions;
5 cananian 1.1.2.1
6 cananian 1.1.2.1 import harpoon.ClassFile.HClass;
7 cananian 1.1.2.1 import harpoon.ClassFile.HClassMutator;
8 cananian 1.1.2.1 import harpoon.ClassFile.HField;
9 cananian 1.1.2.2 import harpoon.ClassFile.Linker;
10 cananian 1.1.2.1 import harpoon.Util.Util;
11 cananian 1.5 import java.util.Collections;
12 cananian 1.5 import java.util.HashSet;
13 cananian 1.1.2.1 import java.util.HashMap;
14 cananian 1.1.2.1 import java.util.Map;
15 cananian 1.5 import java.util.Set;
16 cananian 1.1.2.1
17 cananian 1.1.2.1 /**
18 cananian 1.1.2.1 * <code>BitFieldNumbering</code> finds a bit-position and a field to
19 cananian 1.1.2.1 * embed boolean flags describing object fields.
20 cananian 1.1.2.1 *
21 cananian 1.1.2.1 * @author C. Scott Ananian <cananian@alumni.princeton.edu>
22 cananian 1.5 * @version $Id: BitFieldNumbering.java,v 1.5 2003/07/21 21:21:49 cananian Exp $
23 cananian 1.1.2.1 */
24 cananian 1.1.2.2 public class BitFieldNumbering {
25 cananian 1.1.2.1 // note: for 64-bit archs, might be worthwhile to make fields 64 bits.
26 cananian 1.1.2.1 public static final HClass FIELD_TYPE = HClass.Int;
27 cananian 1.1.2.1 public static final int BITS_IN_FIELD = 32;
28 cananian 1.1.2.1
29 cananian 1.1.2.1 // unique suffix for the fields created by this BitFieldNumbering.
30 cananian 1.1.2.1 private final String suffix;
31 cananian 1.1.2.2 // cache HClass for java.lang.Object
32 cananian 1.1.2.2 private final HClass HCobject;
33 cananian 1.5 // set of all referenced 'bitfield' fields: mutable version.
34 cananian 1.5 private final Set<HField> _bitfields = new HashSet<HField>();
35 cananian 1.5 /** Set of all fields returned as part of a <code>BitFieldTuple</code>
36 cananian 1.5 * by <code>bfLoc</code> or <code>arrayBitField</code>. */
37 cananian 1.5 public final Set<HField> bitfields =
38 cananian 1.5 Collections.unmodifiableSet(_bitfields);
39 cananian 1.1.2.1
40 cananian 1.1.2.1 /** Creates a <code>BitFieldNumbering</code>. */
41 cananian 1.1.2.2 public BitFieldNumbering(Linker l) { this(l, ""); }
42 cananian 1.1.2.2 public BitFieldNumbering(Linker l, String suffix) {
43 cananian 1.1.2.2 this.suffix=suffix;
44 cananian 1.1.2.2 this.HCobject = l.forName("java.lang.Object");
45 cananian 1.1.2.2 }
46 cananian 1.1.2.1
47 cananian 1.1.2.2 public static class BitFieldTuple {
48 cananian 1.1.2.2 public final HField field;
49 cananian 1.1.2.2 public final int bit;
50 cananian 1.1.2.1 BitFieldTuple(HField field, int bit) {this.field=field; this.bit=bit;}
51 cananian 1.1.2.1 public String toString() { return "Bit "+bit+" of "+field; }
52 cananian 1.1.2.1 }
53 cananian 1.1.2.1 public BitFieldTuple bfLoc(HField hf) {
54 cananian 1.1.2.1 int n = fieldNumber(hf);
55 cananian 1.1.2.1 // which class would the check field belong to?
56 cananian 1.1.2.2 // answer: same class as contains the definition of field #(marker)
57 cananian 1.1.2.1 int marker = BITS_IN_FIELD * (n/BITS_IN_FIELD);
58 cananian 1.1.2.1 HClass hc = hf.getDeclaringClass();
59 cananian 1.1.2.2 if (marker!=0) {
60 cananian 1.1.2.2 while (classNumber(hc.getSuperclass()) > marker)
61 cananian 1.1.2.2 hc = hc.getSuperclass();
62 cananian 1.1.2.2 } else {
63 cananian 1.1.2.2 /* special case: zero'th field goes in java.lang.Object.
64 cananian 1.1.2.2 * this is to make the array case more regular. */
65 cananian 1.1.2.2 hc = HCobject;
66 cananian 1.1.2.2 }
67 cananian 1.1.2.1 // okay, fetch this field, creating if necessary.
68 cananian 1.1.2.1 HField bff = getOrMake(hc, n/BITS_IN_FIELD);
69 cananian 1.1.2.1 // done.
70 cananian 1.1.2.1 return new BitFieldTuple(bff, n % BITS_IN_FIELD);
71 cananian 1.1.2.1 }
72 cananian 1.1.2.1 public HField arrayBitField(HClass hc) {
73 cananian 1.3.2.1 assert hc.isArray();
74 cananian 1.1.2.2 /* okay, first 'field info' field is used for arrays. */
75 cananian 1.1.2.2 return getOrMake(HCobject, 0);
76 cananian 1.1.2.1 }
77 cananian 1.1.2.1
78 cananian 1.1.2.1 // fetch a bitfield, creating if necessary.
79 cananian 1.1.2.1 private HField getOrMake(HClass where, int which) {
80 cananian 1.1.2.2 /* for safety: always call classNumber(where) to cache the field
81 cananian 1.1.2.2 * numbering for 'where' *before* we screw it up by adding fields. */
82 cananian 1.1.2.2 classNumber(where);
83 cananian 1.1.2.2 /* okay, now fetch/make the bitfield field. */
84 cananian 1.1.2.1 String fieldname="$$bitfield"+which+suffix;
85 cananian 1.1.2.1 try {
86 cananian 1.1.2.1 return where.getDeclaredField(fieldname);
87 cananian 1.1.2.1 } catch (NoSuchFieldError nsfe) {
88 cananian 1.5 HField hf =
89 cananian 1.5 where.getMutator().addDeclaredField(fieldname, FIELD_TYPE);
90 cananian 1.5 _bitfields.add(hf);
91 cananian 1.5 return hf;
92 cananian 1.1.2.1 }
93 cananian 1.1.2.1 }
94 cananian 1.1.2.1 // field numbering.
95 cananian 1.5 final Map<HField,Integer> fieldNumbers = new HashMap<HField,Integer>();
96 cananian 1.5 final Map<HClass,Integer> classNumbers = new HashMap<HClass,Integer>();
97 cananian 1.1.2.1 private int fieldNumber(HField hf) {
98 cananian 1.3.2.1 assert !hf.isStatic();
99 cananian 1.3.2.1 assert !hf.getDeclaringClass().isInterface();
100 cananian 1.1.2.1 if (!fieldNumbers.containsKey(hf))
101 cananian 1.1.2.1 classNumber(hf.getDeclaringClass());
102 cananian 1.5 assert fieldNumbers.containsKey(hf) : hf + " / "+fieldNumbers;
103 cananian 1.5 return fieldNumbers.get(hf).intValue();
104 cananian 1.1.2.1 }
105 cananian 1.1.2.2 /* all fields in 'hc' are numbered *strictly less than* classNumber(hc) */
106 cananian 1.1.2.1 private int classNumber(HClass hc) {
107 cananian 1.3.2.1 assert !hc.isArray();
108 cananian 1.3.2.1 assert !hc.isInterface();
109 cananian 1.1.2.1 if (!classNumbers.containsKey(hc)) {
110 cananian 1.1.2.1 HClass sc = hc.getSuperclass();
111 cananian 1.1.2.1 int start = (sc==null) ? 0 : classNumber(sc);
112 cananian 1.1.2.1 HField[] hfa = hc.getDeclaredFields();
113 cananian 1.1.2.1 for (int i=0; i<hfa.length; i++)
114 cananian 1.1.2.1 if (!hfa[i].isStatic())
115 cananian 1.1.2.1 fieldNumbers.put(hfa[i], new Integer(start++));
116 cananian 1.1.2.1 classNumbers.put(hc, new Integer(start));
117 cananian 1.1.2.1 }
118 cananian 1.5 return classNumbers.get(hc).intValue();
119 cananian 1.1.2.1 }
120 cananian 1.2 }