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My first initial commit with all of mine experimental changes.

Dmitry Kabak (userdima committed 13 years ago

Commit d37b88d1 parent 3f5b46618352 files · +2598093 −-8690Browse files

Showing the changes to java/pkg/sun/invoke/util/VerifyType.java (1 of 18352 files). Show all

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java/pkg/sun/invoke/util/VerifyType.java+231−0
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1+/*
2+ * Copyright (c) 2008, 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. 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+
26+package sun.invoke.util;
27+
28+import java.lang.invoke.MethodType;
29+import sun.invoke.empty.Empty;
30+
31+/**
32+ * This class centralizes information about the JVM verifier
33+ * and its requirements about type correctness.
34+ * @author jrose
35+ */
36+public class VerifyType {
37+
38+ private VerifyType() { } // cannot instantiate
39+
40+ /**
41+ * True if a value can be stacked as the source type and unstacked as the
42+ * destination type, without violating the JVM's type consistency.
43+ *
44+ * @param call the type of a stacked value
45+ * @param recv the type by which we'd like to treat it
46+ * @return whether the retyping can be done without motion or reformatting
47+ */
48+ public static boolean isNullConversion(Class<?> src, Class<?> dst) {
49+ if (src == dst) return true;
50+ // Verifier allows any interface to be treated as Object:
51+ if (dst.isInterface()) dst = Object.class;
52+ if (src.isInterface()) src = Object.class;
53+ if (src == dst) return true; // check again
54+ if (dst == void.class) return true; // drop any return value
55+ if (isNullType(src)) return !dst.isPrimitive();
56+ if (!src.isPrimitive()) return dst.isAssignableFrom(src);
57+ if (!dst.isPrimitive()) return false;
58+ // Verifier allows an int to carry byte, short, char, or even boolean:
59+ Wrapper sw = Wrapper.forPrimitiveType(src);
60+ if (dst == int.class) return sw.isSubwordOrInt();
61+ Wrapper dw = Wrapper.forPrimitiveType(dst);
62+ if (!sw.isSubwordOrInt()) return false;
63+ if (!dw.isSubwordOrInt()) return false;
64+ if (!dw.isSigned() && sw.isSigned()) return false;
65+ return dw.bitWidth() > sw.bitWidth();
66+ }
67+
68+ /**
69+ * Specialization of isNullConversion to reference types.
70+
71+ * @param call the type of a stacked value
72+ * @param recv the reference type by which we'd like to treat it
73+ * @return whether the retyping can be done without a cast
74+ */
75+ public static boolean isNullReferenceConversion(Class<?> src, Class<?> dst) {
76+ assert(!dst.isPrimitive());
77+ if (dst.isInterface()) return true; // verifier allows this
78+ if (isNullType(src)) return true;
79+ return dst.isAssignableFrom(src);
80+ }
81+
82+ /**
83+ * Is the given type java.lang.Null or an equivalent null-only type?
84+ */
85+ public static boolean isNullType(Class<?> type) {
86+ if (type == null) return false;
87+ return type == NULL_CLASS
88+ // This one may also be used as a null type.
89+ // TO DO: Decide if we really want to legitimize it here.
90+ // Probably we do, unless java.lang.Null really makes it into Java 7
91+ //|| type == Void.class
92+ // Locally known null-only class:
93+ || type == Empty.class
94+ ;
95+ }
96+ private static final Class<?> NULL_CLASS;
97+ static {
98+ Class<?> nullClass = null;
99+ try {
100+ nullClass = Class.forName("java.lang.Null");
101+ } catch (ClassNotFoundException ex) {
102+ // OK, we'll cope
103+ }
104+ NULL_CLASS = nullClass;
105+ }
106+
107+ /**
108+ * True if a method handle can receive a call under a slightly different
109+ * method type, without moving or reformatting any stack elements.
110+ *
111+ * @param call the type of call being made
112+ * @param recv the type of the method handle receiving the call
113+ * @return whether the retyping can be done without motion or reformatting
114+ */
115+ public static boolean isNullConversion(MethodType call, MethodType recv) {
116+ if (call == recv) return true;
117+ int len = call.parameterCount();
118+ if (len != recv.parameterCount()) return false;
119+ for (int i = 0; i < len; i++)
120+ if (!isNullConversion(call.parameterType(i), recv.parameterType(i)))
121+ return false;
122+ return isNullConversion(recv.returnType(), call.returnType());
123+ }
124+
125+ //TO DO: isRawConversion
126+
127+ /**
128+ * Determine if the JVM verifier allows a value of type call to be
129+ * passed to a formal parameter (or return variable) of type recv.
130+ * Returns 1 if the verifier allows the types to match without conversion.
131+ * Returns -1 if the types can be made to match by a JVM-supported adapter.
132+ * Cases supported are:
133+ * <ul><li>checkcast
134+ * </li><li>conversion between any two integral types (but not floats)
135+ * </li><li>unboxing from a wrapper to its corresponding primitive type
136+ * </li><li>conversion in either direction between float and double
137+ * </li></ul>
138+ * (Autoboxing is not supported here; it must be done via Java code.)
139+ * Returns 0 otherwise.
140+ */
141+ public static int canPassUnchecked(Class<?> src, Class<?> dst) {
142+ if (src == dst)
143+ return 1;
144+
145+ if (dst.isPrimitive()) {
146+ if (dst == void.class)
147+ // Return anything to a caller expecting void.
148+ // This is a property of the implementation, which links
149+ // return values via a register rather than via a stack push.
150+ // This makes it possible to ignore cleanly.
151+ return 1;
152+ if (src == void.class)
153+ return 0; // void-to-something?
154+ if (!src.isPrimitive())
155+ // Cannot pass a reference to any primitive type (exc. void).
156+ return 0;
157+ Wrapper sw = Wrapper.forPrimitiveType(src);
158+ Wrapper dw = Wrapper.forPrimitiveType(dst);
159+ if (sw.isSubwordOrInt() && dw.isSubwordOrInt()) {
160+ if (sw.bitWidth() >= dw.bitWidth())
161+ return -1; // truncation may be required
162+ if (!dw.isSigned() && sw.isSigned())
163+ return -1; // sign elimination may be required
164+ return 1;
165+ }
166+ if (src == float.class || dst == float.class) {
167+ if (src == double.class || dst == double.class)
168+ return -1; // floating conversion may be required
169+ else
170+ return 0; // other primitive conversions NYI
171+ } else {
172+ // all fixed-point conversions are supported
173+ return 0;
174+ }
175+ } else if (src.isPrimitive()) {
176+ // Cannot pass a primitive to any reference type.
177+ // (Maybe allow null.class?)
178+ return 0;
179+ }
180+
181+ // Handle reference types in the rest of the block:
182+
183+ // The verifier treats interfaces exactly like Object.
184+ if (isNullReferenceConversion(src, dst))
185+ // pass any reference to object or an arb. interface
186+ return 1;
187+ // else it's a definite "maybe" (cast is required)
188+ return -1;
189+ }
190+
191+ public static int canPassRaw(Class<?> src, Class<?> dst) {
192+ if (dst.isPrimitive()) {
193+ if (dst == void.class)
194+ // As above, return anything to a caller expecting void.
195+ return 1;
196+ if (src == void.class)
197+ // Special permission for raw conversions: allow a void
198+ // to be captured as a garbage int.
199+ // Caller promises that the actual value will be disregarded.
200+ return dst == int.class ? 1 : 0;
201+ if (isNullType(src))
202+ // Special permission for raw conversions: allow a null
203+ // to be reinterpreted as anything. For objects, it is safe,
204+ // and for primitives you get a garbage value (probably zero).
205+ return 1;
206+ if (!src.isPrimitive())
207+ return 0;
208+ Wrapper sw = Wrapper.forPrimitiveType(src);
209+ Wrapper dw = Wrapper.forPrimitiveType(dst);
210+ if (sw.stackSlots() == dw.stackSlots())
211+ return 1; // can do a reinterpret-cast on a stacked primitive
212+ if (sw.isSubwordOrInt() && dw == Wrapper.VOID)
213+ return 1; // can drop an outgoing int value
214+ return 0;
215+ } else if (src.isPrimitive()) {
216+ return 0;
217+ }
218+
219+ // Both references.
220+ if (isNullReferenceConversion(src, dst))
221+ return 1;
222+ return -1;
223+ }
224+
225+ public static boolean isSpreadArgType(Class<?> spreadArg) {
226+ return spreadArg.isArray();
227+ }
228+ public static Class<?> spreadArgElementType(Class<?> spreadArg, int i) {
229+ return spreadArg.getComponentType();
230+ }
231+}