1 /*
2 * Copyright (c) 2025, 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. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25 package jdk.internal.classfile.impl;
26
27 import java.lang.classfile.constantpool.ConstantPoolBuilder;
28 import java.lang.classfile.constantpool.Utf8Entry;
29 import java.util.Arrays;
30
31 import static java.lang.classfile.ClassFile.ACC_STATIC;
32 import static java.lang.classfile.ClassFile.ACC_STRICT;
33
34 /**
35 * An interface to obtain field properties for direct class builders.
36 * Required to filter strict instance fields for stack map generation.
37 * Public for benchmark access.
38 */
39 public sealed interface WritableField extends Util.Writable
40 permits FieldImpl, DirectFieldBuilder {
41 Utf8Entry fieldName();
42 Utf8Entry fieldType();
43 int fieldFlags();
44
45 static WritableField.UnsetField[] filterStrictInstanceFields(ConstantPoolBuilder cpb, WritableField[] array, int count) {
46 // assume there's no toctou for trusted incoming array
47 int size = 0;
48 for (int i = 0; i < count; i++) {
49 var field = array[i];
50 if ((field.fieldFlags() & (ACC_STATIC | ACC_STRICT)) == ACC_STRICT) {
51 size++;
52 }
53 }
54 if (size == 0)
55 return UnsetField.EMPTY_ARRAY;
56 UnsetField[] ret = new UnsetField[size];
57 int j = 0;
58 for (int i = 0; i < count; i++) {
59 var field = array[i];
60 if ((field.fieldFlags() & (ACC_STATIC | ACC_STRICT)) == ACC_STRICT) {
61 ret[j++] = new UnsetField(AbstractPoolEntry.maybeClone(cpb, field.fieldName()),
62 AbstractPoolEntry.maybeClone(cpb, field.fieldType()));
63 }
64 }
65 assert j == size : "toctou: " + j + " != " + size;
66 Arrays.sort(ret);
67 return ret;
68 }
69
70 // The captured information of unset fields, pool entries localized to class writing context
71 // avoid creating NAT until we need to write the fields to stack maps
72 record UnsetField(Utf8Entry name, Utf8Entry type) implements Comparable<UnsetField> {
73 public UnsetField {
74 assert Util.checkConstantPoolsCompatible(name.constantPool(), type.constantPool());
75 }
76 public static final UnsetField[] EMPTY_ARRAY = new UnsetField[0];
77
78 public static UnsetField[] copyArray(UnsetField[] incoming, int resultLen) {
79 assert resultLen <= incoming.length : resultLen + " > " + incoming.length;
80 return resultLen == 0 ? EMPTY_ARRAY : Arrays.copyOf(incoming, resultLen, UnsetField[].class);
81 }
82
83 public static boolean matches(UnsetField[] one, int sizeOne, UnsetField[] two, int sizeTwo) {
84 if (sizeOne != sizeTwo)
85 return false;
86 for (int i = 0; i < sizeOne; i++) {
87 if (!one[i].equals(two[i])) {
88 return false;
89 }
90 }
91 return true;
92 }
93
94 // Warning: inconsistent with equals (which uses UTF8 object equality)
95 @Override
96 public int compareTo(UnsetField o) {
97 assert Util.checkConstantPoolsCompatible(name.constantPool(), o.name.constantPool());
98 var ret = Integer.compare(name.index(), o.name.index());
99 if (ret != 0)
100 return ret;
101 return Integer.compare(type.index(), o.type.index());
102 }
103 }
104 }