1 /*
2 * Copyright (c) 2008, 2012, 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 java.lang.invoke;
27
28 import sun.invoke.util.Wrapper;
29 import static java.lang.invoke.MethodHandleStatics.*;
30 import static java.lang.invoke.MethodHandleNatives.Constants.*;
31
32 /**
33 * Shared information for a group of method types, which differ
34 * only by reference types, and therefore share a common erasure
35 * and wrapping.
36 * <p>
37 * For an empirical discussion of the structure of method types,
38 * see <a href="http://groups.google.com/group/jvm-languages/browse_thread/thread/ac9308ae74da9b7e/">
39 * the thread "Avoiding Boxing" on jvm-languages</a>.
40 * There are approximately 2000 distinct erased method types in the JDK.
41 * There are a little over 10 times that number of unerased types.
42 * No more than half of these are likely to be loaded at once.
43 * @author John Rose
44 */
45 final class MethodTypeForm {
46 final int[] argToSlotTable, slotToArgTable;
47 final long argCounts; // packed slot & value counts
48 final long primCounts; // packed prim & double counts
49 final int vmslots; // total number of parameter slots
50 final MethodType erasedType; // the canonical erasure
51 final MethodType basicType; // the canonical erasure, with primitives simplified
52
53 // Cached adapter information:
54 /*lazy*/ MethodHandle genericInvoker; // JVM hook for inexact invoke
55 /*lazy*/ MethodHandle basicInvoker; // cached instance of MH.invokeBasic
56 /*lazy*/ MethodHandle namedFunctionInvoker; // cached helper for LF.NamedFunction
57
58 // Cached lambda form information, for basic types only:
59 final LambdaForm[] lambdaForms;
60 // Indexes into lambdaForms:
61 static final int
62 LF_INVVIRTUAL = 0, // DMH invokeVirtual
63 LF_INVSTATIC = 1,
64 LF_INVSPECIAL = 2,
65 LF_NEWINVSPECIAL = 3,
66 LF_INVINTERFACE = 4,
67 LF_INVSTATIC_INIT = 5, // DMH invokeStatic with <clinit> barrier
68 LF_INTERPRET = 6, // LF interpreter
69 LF_COUNTER = 7, // CMH wrapper
70 LF_REINVOKE = 8, // other wrapper
71 LF_EX_LINKER = 9, // invokeExact_MT
72 LF_EX_INVOKER = 10, // invokeExact MH
73 LF_GEN_LINKER = 11,
74 LF_GEN_INVOKER = 12,
75 LF_CS_LINKER = 13, // linkToCallSite_CS
76 LF_LIMIT = 14;
77
78 public MethodType erasedType() {
79 return erasedType;
80 }
81
82 public MethodType basicType() {
83 return basicType;
84 }
85
86 public LambdaForm cachedLambdaForm(int which) {
87 return lambdaForms[which];
88 }
89
90 public LambdaForm setCachedLambdaForm(int which, LambdaForm form) {
91 // Should we perform some sort of CAS, to avoid racy duplication?
92 return lambdaForms[which] = form;
93 }
94
95 public MethodHandle basicInvoker() {
96 assert(erasedType == basicType) : "erasedType: " + erasedType + " != basicType: " + basicType; // primitives must be flattened also
97 MethodHandle invoker = basicInvoker;
98 if (invoker != null) return invoker;
99 invoker = basicType.invokers().makeBasicInvoker();
100 basicInvoker = invoker;
101 return invoker;
102 }
103
104 /**
105 * Build an MTF for a given type, which must have all references erased to Object.
106 * This MTF will stand for that type and all un-erased variations.
107 * Eagerly compute some basic properties of the type, common to all variations.
108 */
109 protected MethodTypeForm(MethodType erasedType) {
110 this.erasedType = erasedType;
111
112 Class<?>[] ptypes = erasedType.ptypes();
113 int ptypeCount = ptypes.length;
114 int pslotCount = ptypeCount; // temp. estimate
115 int rtypeCount = 1; // temp. estimate
116 int rslotCount = 1; // temp. estimate
117
118 int[] argToSlotTab = null, slotToArgTab = null;
119
120 // Walk the argument types, looking for primitives.
121 int pac = 0, lac = 0, prc = 0, lrc = 0;
122 Class<?>[] epts = ptypes;
123 Class<?>[] bpts = epts;
124 for (int i = 0; i < epts.length; i++) {
125 Class<?> pt = epts[i];
126 if (pt != Object.class) {
127 ++pac;
128 Wrapper w = Wrapper.forPrimitiveType(pt);
129 if (w.isDoubleWord()) ++lac;
130 if (w.isSubwordOrInt() && pt != int.class) {
131 if (bpts == epts)
132 bpts = bpts.clone();
133 bpts[i] = int.class;
134 }
135 }
136 }
137 pslotCount += lac; // #slots = #args + #longs
138 Class<?> rt = erasedType.returnType();
139 Class<?> bt = rt;
140 if (rt != Object.class) {
141 ++prc; // even void.class counts as a prim here
142 Wrapper w = Wrapper.forPrimitiveType(rt);
143 if (w.isDoubleWord()) ++lrc;
144 if (w.isSubwordOrInt() && rt != int.class)
145 bt = int.class;
146 // adjust #slots, #args
147 if (rt == void.class)
148 rtypeCount = rslotCount = 0;
149 else
150 rslotCount += lrc;
151 }
152 if (epts == bpts && bt == rt) {
153 this.basicType = erasedType;
154 } else {
155 this.basicType = MethodType.makeImpl(bt, bpts, true);
156 }
157 if (lac != 0) {
158 int slot = ptypeCount + lac;
159 slotToArgTab = new int[slot+1];
160 argToSlotTab = new int[1+ptypeCount];
161 argToSlotTab[0] = slot; // argument "-1" is past end of slots
162 for (int i = 0; i < epts.length; i++) {
163 Class<?> pt = epts[i];
164 Wrapper w = Wrapper.forBasicType(pt);
165 if (w.isDoubleWord()) --slot;
166 --slot;
167 slotToArgTab[slot] = i+1; // "+1" see argSlotToParameter note
168 argToSlotTab[1+i] = slot;
169 }
170 assert(slot == 0); // filled the table
171 }
172 this.primCounts = pack(lrc, prc, lac, pac);
173 this.argCounts = pack(rslotCount, rtypeCount, pslotCount, ptypeCount);
174 if (slotToArgTab == null) {
175 int slot = ptypeCount; // first arg is deepest in stack
176 slotToArgTab = new int[slot+1];
177 argToSlotTab = new int[1+ptypeCount];
178 argToSlotTab[0] = slot; // argument "-1" is past end of slots
179 for (int i = 0; i < ptypeCount; i++) {
180 --slot;
181 slotToArgTab[slot] = i+1; // "+1" see argSlotToParameter note
182 argToSlotTab[1+i] = slot;
183 }
184 }
185 this.argToSlotTable = argToSlotTab;
186 this.slotToArgTable = slotToArgTab;
187
188 if (pslotCount >= 256) throw newIllegalArgumentException("too many arguments");
189
190 // send a few bits down to the JVM:
191 this.vmslots = parameterSlotCount();
192
193 if (basicType == erasedType) {
194 lambdaForms = new LambdaForm[LF_LIMIT];
195 } else {
196 lambdaForms = null; // could be basicType.form().lambdaForms;
197 }
198 }
199
200 private static long pack(int a, int b, int c, int d) {
201 assert(((a|b|c|d) & ~0xFFFF) == 0);
202 long hw = ((a << 16) | b), lw = ((c << 16) | d);
203 return (hw << 32) | lw;
204 }
205 private static char unpack(long packed, int word) { // word==0 => return a, ==3 => return d
206 assert(word <= 3);
207 return (char)(packed >> ((3-word) * 16));
208 }
209
210 public int parameterCount() { // # outgoing values
211 return unpack(argCounts, 3);
212 }
213 public int parameterSlotCount() { // # outgoing interpreter slots
214 return unpack(argCounts, 2);
215 }
216 public int returnCount() { // = 0 (V), or 1
217 return unpack(argCounts, 1);
218 }
219 public int returnSlotCount() { // = 0 (V), 2 (J/D), or 1
220 return unpack(argCounts, 0);
221 }
222 public int primitiveParameterCount() {
223 return unpack(primCounts, 3);
224 }
225 public int longPrimitiveParameterCount() {
226 return unpack(primCounts, 2);
227 }
228 public int primitiveReturnCount() { // = 0 (obj), or 1
229 return unpack(primCounts, 1);
230 }
231 public int longPrimitiveReturnCount() { // = 1 (J/D), or 0
232 return unpack(primCounts, 0);
233 }
234 public boolean hasPrimitives() {
235 return primCounts != 0;
236 }
237 public boolean hasNonVoidPrimitives() {
238 if (primCounts == 0) return false;
239 if (primitiveParameterCount() != 0) return true;
240 return (primitiveReturnCount() != 0 && returnCount() != 0);
241 }
242 public boolean hasLongPrimitives() {
243 return (longPrimitiveParameterCount() | longPrimitiveReturnCount()) != 0;
244 }
245 public int parameterToArgSlot(int i) {
246 return argToSlotTable[1+i];
247 }
248 public int argSlotToParameter(int argSlot) {
249 // Note: Empty slots are represented by zero in this table.
250 // Valid arguments slots contain incremented entries, so as to be non-zero.
251 // We return -1 the caller to mean an empty slot.
252 return slotToArgTable[argSlot] - 1;
253 }
254
255 static MethodTypeForm findForm(MethodType mt) {
256 MethodType erased = canonicalize(mt, ERASE, ERASE);
257 if (erased == null) {
258 // It is already erased. Make a new MethodTypeForm.
259 return new MethodTypeForm(mt);
260 } else {
261 // Share the MethodTypeForm with the erased version.
262 return erased.form();
263 }
264 }
265
266 /** Codes for {@link #canonicalize(java.lang.Class, int)}.
267 * ERASE means change every reference to {@code Object}.
268 * WRAP means convert primitives (including {@code void} to their
269 * corresponding wrapper types. UNWRAP means the reverse of WRAP.
270 * INTS means convert all non-void primitive types to int or long,
271 * according to size. LONGS means convert all non-void primitives
272 * to long, regardless of size. RAW_RETURN means convert a type
273 * (assumed to be a return type) to int if it is smaller than an int,
274 * or if it is void.
275 */
276 public static final int NO_CHANGE = 0, ERASE = 1, WRAP = 2, UNWRAP = 3, INTS = 4, LONGS = 5, RAW_RETURN = 6;
277
278 /** Canonicalize the types in the given method type.
279 * If any types change, intern the new type, and return it.
280 * Otherwise return null.
281 */
282 public static MethodType canonicalize(MethodType mt, int howRet, int howArgs) {
283 Class<?>[] ptypes = mt.ptypes();
284 Class<?>[] ptc = MethodTypeForm.canonicalizes(ptypes, howArgs);
285 Class<?> rtype = mt.returnType();
286 Class<?> rtc = MethodTypeForm.canonicalize(rtype, howRet);
287 if (ptc == null && rtc == null) {
288 // It is already canonical.
289 return null;
290 }
291 // Find the erased version of the method type:
292 if (rtc == null) rtc = rtype;
293 if (ptc == null) ptc = ptypes;
294 return MethodType.makeImpl(rtc, ptc, true);
295 }
296
297 /** Canonicalize the given return or param type.
298 * Return null if the type is already canonicalized.
299 */
300 static Class<?> canonicalize(Class<?> t, int how) {
301 Class<?> ct;
302 if (t == Object.class) {
303 // no change, ever
304 } else if (!t.isPrimitive()) {
305 switch (how) {
306 case UNWRAP:
307 ct = Wrapper.asPrimitiveType(t);
308 if (ct != t) return ct;
309 break;
310 case RAW_RETURN:
311 case ERASE:
312 return Object.class;
313 }
314 } else if (t == void.class) {
315 // no change, usually
316 switch (how) {
317 case RAW_RETURN:
318 return int.class;
319 case WRAP:
320 return Void.class;
321 }
322 } else {
323 // non-void primitive
324 switch (how) {
325 case WRAP:
326 return Wrapper.asWrapperType(t);
327 case INTS:
328 if (t == int.class || t == long.class)
329 return null; // no change
330 if (t == double.class)
331 return long.class;
332 return int.class;
333 case LONGS:
334 if (t == long.class)
335 return null; // no change
336 return long.class;
337 case RAW_RETURN:
338 if (t == int.class || t == long.class ||
339 t == float.class || t == double.class)
340 return null; // no change
341 // everything else returns as an int
342 return int.class;
343 }
344 }
345 // no change; return null to signify
346 return null;
347 }
348
349 /** Canonicalize each param type in the given array.
350 * Return null if all types are already canonicalized.
351 */
352 static Class<?>[] canonicalizes(Class<?>[] ts, int how) {
353 Class<?>[] cs = null;
354 for (int imax = ts.length, i = 0; i < imax; i++) {
355 Class<?> c = canonicalize(ts[i], how);
356 if (c == void.class)
357 c = null; // a Void parameter was unwrapped to void; ignore
358 if (c != null) {
359 if (cs == null)
360 cs = ts.clone();
361 cs[i] = c;
362 }
363 }
364 return cs;
365 }
366
367 @Override
368 public String toString() {
369 return "Form"+erasedType;
370 }
371
372 }