1 /*
2 * Copyright (c) 2008, 2013, 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 import static java.lang.invoke.MethodHandles.Lookup.IMPL_LOOKUP;
32
33 /**
34 * Shared information for a group of method types, which differ
35 * only by reference types, and therefore share a common erasure
36 * and wrapping.
37 * <p>
38 * For an empirical discussion of the structure of method types,
39 * see <a href="http://groups.google.com/group/jvm-languages/browse_thread/thread/ac9308ae74da9b7e/">
40 * the thread "Avoiding Boxing" on jvm-languages</a>.
41 * There are approximately 2000 distinct erased method types in the JDK.
42 * There are a little over 10 times that number of unerased types.
43 * No more than half of these are likely to be loaded at once.
44 * @author John Rose
45 */
46 final class MethodTypeForm {
47 final int[] argToSlotTable, slotToArgTable;
48 final long argCounts; // packed slot & value counts
49 final long primCounts; // packed prim & double counts
50 final MethodType erasedType; // the canonical erasure
51 final MethodType basicType; // the canonical erasure, with primitives simplified
52
53 // Cached adapter information:
54 @Stable final MethodHandle[] methodHandles;
55 // Indexes into methodHandles:
56 static final int
57 MH_BASIC_INV = 0, // cached instance of MH.invokeBasic
58 MH_NF_INV = 1, // cached helper for LF.NamedFunction
59 MH_UNINIT_CS = 2, // uninitialized call site
60 MH_LIMIT = 3;
61
62 // Cached lambda form information, for basic types only:
63 final @Stable LambdaForm[] lambdaForms;
64 // Indexes into lambdaForms:
65 static final int
66 LF_INVVIRTUAL = 0, // DMH invokeVirtual
67 LF_INVSTATIC = 1,
68 LF_INVSPECIAL = 2,
69 LF_NEWINVSPECIAL = 3,
70 LF_INVINTERFACE = 4,
71 LF_INVSTATIC_INIT = 5, // DMH invokeStatic with <clinit> barrier
72 LF_INTERPRET = 6, // LF interpreter
73 LF_REBIND = 7, // BoundMethodHandle
74 LF_DELEGATE = 8, // DelegatingMethodHandle
75 LF_EX_LINKER = 9, // invokeExact_MT (for invokehandle)
76 LF_EX_INVOKER = 10, // MHs.invokeExact
77 LF_GEN_LINKER = 11, // generic invoke_MT (for invokehandle)
78 LF_GEN_INVOKER = 12, // generic MHs.invoke
79 LF_CS_LINKER = 13, // linkToCallSite_CS
80 LF_MH_LINKER = 14, // linkToCallSite_MH
81 LF_GWC = 15, // guardWithCatch (catchException)
82 LF_LIMIT = 16;
83
84 /** Return the type corresponding uniquely (1-1) to this MT-form.
85 * It might have any primitive returns or arguments, but will have no references except Object.
86 */
87 public MethodType erasedType() {
88 return erasedType;
89 }
90
91 /** Return the basic type derived from the erased type of this MT-form.
92 * A basic type is erased (all references Object) and also has all primitive
93 * types (except int, long, float, double, void) normalized to int.
94 * Such basic types correspond to low-level JVM calling sequences.
95 */
96 public MethodType basicType() {
97 return basicType;
98 }
99
100 private boolean assertIsBasicType() {
101 // primitives must be flattened also
102 assert(erasedType == basicType)
103 : "erasedType: " + erasedType + " != basicType: " + basicType;
104 return true;
105 }
106
107 public MethodHandle cachedMethodHandle(int which) {
108 assert(assertIsBasicType());
109 return methodHandles[which];
110 }
111
112 synchronized public MethodHandle setCachedMethodHandle(int which, MethodHandle mh) {
113 // Simulate a CAS, to avoid racy duplication of results.
114 MethodHandle prev = methodHandles[which];
115 if (prev != null) return prev;
116 return methodHandles[which] = mh;
117 }
118
119 public LambdaForm cachedLambdaForm(int which) {
120 assert(assertIsBasicType());
121 return lambdaForms[which];
122 }
123
124 synchronized public LambdaForm setCachedLambdaForm(int which, LambdaForm form) {
125 // Simulate a CAS, to avoid racy duplication of results.
126 LambdaForm prev = lambdaForms[which];
127 if (prev != null) return prev;
128 return lambdaForms[which] = form;
129 }
130
131 /**
132 * Build an MTF for a given type, which must have all references erased to Object.
133 * This MTF will stand for that type and all un-erased variations.
134 * Eagerly compute some basic properties of the type, common to all variations.
135 */
136 protected MethodTypeForm(MethodType erasedType) {
137 this.erasedType = erasedType;
138
139 Class<?>[] ptypes = erasedType.ptypes();
140 int ptypeCount = ptypes.length;
141 int pslotCount = ptypeCount; // temp. estimate
142 int rtypeCount = 1; // temp. estimate
143 int rslotCount = 1; // temp. estimate
144
145 int[] argToSlotTab = null, slotToArgTab = null;
146
147 // Walk the argument types, looking for primitives.
148 int pac = 0, lac = 0, prc = 0, lrc = 0;
149 Class<?>[] epts = ptypes;
150 Class<?>[] bpts = epts;
151 for (int i = 0; i < epts.length; i++) {
152 Class<?> pt = epts[i];
153 if (pt != Object.class) {
154 ++pac;
155 Wrapper w = Wrapper.forPrimitiveType(pt);
156 if (w.isDoubleWord()) ++lac;
157 if (w.isSubwordOrInt() && pt != int.class) {
158 if (bpts == epts)
159 bpts = bpts.clone();
160 bpts[i] = int.class;
161 }
162 }
163 }
164 pslotCount += lac; // #slots = #args + #longs
165 Class<?> rt = erasedType.returnType();
166 Class<?> bt = rt;
167 if (rt != Object.class) {
168 ++prc; // even void.class counts as a prim here
169 Wrapper w = Wrapper.forPrimitiveType(rt);
170 if (w.isDoubleWord()) ++lrc;
171 if (w.isSubwordOrInt() && rt != int.class)
172 bt = int.class;
173 // adjust #slots, #args
174 if (rt == void.class)
175 rtypeCount = rslotCount = 0;
176 else
177 rslotCount += lrc;
178 }
179 if (epts == bpts && bt == rt) {
180 this.basicType = erasedType;
181 } else {
182 this.basicType = MethodType.makeImpl(bt, bpts, true);
183 // fill in rest of data from the basic type:
184 MethodTypeForm that = this.basicType.form();
185 assert(this != that);
186 this.primCounts = that.primCounts;
187 this.argCounts = that.argCounts;
188 this.argToSlotTable = that.argToSlotTable;
189 this.slotToArgTable = that.slotToArgTable;
190 this.methodHandles = null;
191 this.lambdaForms = null;
192 return;
193 }
194 if (lac != 0) {
195 int slot = ptypeCount + lac;
196 slotToArgTab = new int[slot+1];
197 argToSlotTab = new int[1+ptypeCount];
198 argToSlotTab[0] = slot; // argument "-1" is past end of slots
199 for (int i = 0; i < epts.length; i++) {
200 Class<?> pt = epts[i];
201 Wrapper w = Wrapper.forBasicType(pt);
202 if (w.isDoubleWord()) --slot;
203 --slot;
204 slotToArgTab[slot] = i+1; // "+1" see argSlotToParameter note
205 argToSlotTab[1+i] = slot;
206 }
207 assert(slot == 0); // filled the table
208 } else if (pac != 0) {
209 // have primitives but no long primitives; share slot counts with generic
210 assert(ptypeCount == pslotCount);
211 MethodTypeForm that = MethodType.genericMethodType(ptypeCount).form();
212 assert(this != that);
213 slotToArgTab = that.slotToArgTable;
214 argToSlotTab = that.argToSlotTable;
215 } else {
216 int slot = ptypeCount; // first arg is deepest in stack
217 slotToArgTab = new int[slot+1];
218 argToSlotTab = new int[1+ptypeCount];
219 argToSlotTab[0] = slot; // argument "-1" is past end of slots
220 for (int i = 0; i < ptypeCount; i++) {
221 --slot;
222 slotToArgTab[slot] = i+1; // "+1" see argSlotToParameter note
223 argToSlotTab[1+i] = slot;
224 }
225 }
226 this.primCounts = pack(lrc, prc, lac, pac);
227 this.argCounts = pack(rslotCount, rtypeCount, pslotCount, ptypeCount);
228 this.argToSlotTable = argToSlotTab;
229 this.slotToArgTable = slotToArgTab;
230
231 if (pslotCount >= 256) throw newIllegalArgumentException("too many arguments");
232
233 // Initialize caches, but only for basic types
234 assert(basicType == erasedType);
235 this.lambdaForms = new LambdaForm[LF_LIMIT];
236 this.methodHandles = new MethodHandle[MH_LIMIT];
237 }
238
239 private static long pack(int a, int b, int c, int d) {
240 assert(((a|b|c|d) & ~0xFFFF) == 0);
241 long hw = ((a << 16) | b), lw = ((c << 16) | d);
242 return (hw << 32) | lw;
243 }
244 private static char unpack(long packed, int word) { // word==0 => return a, ==3 => return d
245 assert(word <= 3);
246 return (char)(packed >> ((3-word) * 16));
247 }
248
249 public int parameterCount() { // # outgoing values
250 return unpack(argCounts, 3);
251 }
252 public int parameterSlotCount() { // # outgoing interpreter slots
253 return unpack(argCounts, 2);
254 }
255 public int returnCount() { // = 0 (V), or 1
256 return unpack(argCounts, 1);
257 }
258 public int returnSlotCount() { // = 0 (V), 2 (J/D), or 1
259 return unpack(argCounts, 0);
260 }
261 public int primitiveParameterCount() {
262 return unpack(primCounts, 3);
263 }
264 public int longPrimitiveParameterCount() {
265 return unpack(primCounts, 2);
266 }
267 public int primitiveReturnCount() { // = 0 (obj), or 1
268 return unpack(primCounts, 1);
269 }
270 public int longPrimitiveReturnCount() { // = 1 (J/D), or 0
271 return unpack(primCounts, 0);
272 }
273 public boolean hasPrimitives() {
274 return primCounts != 0;
275 }
276 public boolean hasNonVoidPrimitives() {
277 if (primCounts == 0) return false;
278 if (primitiveParameterCount() != 0) return true;
279 return (primitiveReturnCount() != 0 && returnCount() != 0);
280 }
281 public boolean hasLongPrimitives() {
282 return (longPrimitiveParameterCount() | longPrimitiveReturnCount()) != 0;
283 }
284 public int parameterToArgSlot(int i) {
285 return argToSlotTable[1+i];
286 }
287 public int argSlotToParameter(int argSlot) {
288 // Note: Empty slots are represented by zero in this table.
289 // Valid arguments slots contain incremented entries, so as to be non-zero.
290 // We return -1 the caller to mean an empty slot.
291 return slotToArgTable[argSlot] - 1;
292 }
293
294 static MethodTypeForm findForm(MethodType mt) {
295 MethodType erased = canonicalize(mt, ERASE, ERASE);
296 if (erased == null) {
297 // It is already erased. Make a new MethodTypeForm.
298 return new MethodTypeForm(mt);
299 } else {
300 // Share the MethodTypeForm with the erased version.
301 return erased.form();
302 }
303 }
304
305 /** Codes for {@link #canonicalize(java.lang.Class, int)}.
306 * ERASE means change every reference to {@code Object}.
307 * WRAP means convert primitives (including {@code void} to their
308 * corresponding wrapper types. UNWRAP means the reverse of WRAP.
309 * INTS means convert all non-void primitive types to int or long,
310 * according to size. LONGS means convert all non-void primitives
311 * to long, regardless of size. RAW_RETURN means convert a type
312 * (assumed to be a return type) to int if it is smaller than an int,
313 * or if it is void.
314 */
315 public static final int NO_CHANGE = 0, ERASE = 1, WRAP = 2, UNWRAP = 3, INTS = 4, LONGS = 5, RAW_RETURN = 6;
316
317 /** Canonicalize the types in the given method type.
318 * If any types change, intern the new type, and return it.
319 * Otherwise return null.
320 */
321 public static MethodType canonicalize(MethodType mt, int howRet, int howArgs) {
322 Class<?>[] ptypes = mt.ptypes();
323 Class<?>[] ptc = MethodTypeForm.canonicalizeAll(ptypes, howArgs);
324 Class<?> rtype = mt.returnType();
325 Class<?> rtc = MethodTypeForm.canonicalize(rtype, howRet);
326 if (ptc == null && rtc == null) {
327 // It is already canonical.
328 return null;
329 }
330 // Find the erased version of the method type:
331 if (rtc == null) rtc = rtype;
332 if (ptc == null) ptc = ptypes;
333 return MethodType.makeImpl(rtc, ptc, true);
334 }
335
336 /** Canonicalize the given return or param type.
337 * Return null if the type is already canonicalized.
338 */
339 static Class<?> canonicalize(Class<?> t, int how) {
340 Class<?> ct;
341 if (t == Object.class) {
342 // no change, ever
343 } else if (!t.isPrimitive()) {
344 switch (how) {
345 case UNWRAP:
346 ct = Wrapper.asPrimitiveType(t);
347 if (ct != t) return ct;
348 break;
349 case RAW_RETURN:
350 case ERASE:
351 return Object.class;
352 }
353 } else if (t == void.class) {
354 // no change, usually
355 switch (how) {
356 case RAW_RETURN:
357 return int.class;
358 case WRAP:
359 return Void.class;
360 }
361 } else {
362 // non-void primitive
363 switch (how) {
364 case WRAP:
365 return Wrapper.asWrapperType(t);
366 case INTS:
367 if (t == int.class || t == long.class)
368 return null; // no change
369 if (t == double.class)
370 return long.class;
371 return int.class;
372 case LONGS:
373 if (t == long.class)
374 return null; // no change
375 return long.class;
376 case RAW_RETURN:
377 if (t == int.class || t == long.class ||
378 t == float.class || t == double.class)
379 return null; // no change
380 // everything else returns as an int
381 return int.class;
382 }
383 }
384 // no change; return null to signify
385 return null;
386 }
387
388 /** Canonicalize each param type in the given array.
389 * Return null if all types are already canonicalized.
390 */
391 static Class<?>[] canonicalizeAll(Class<?>[] ts, int how) {
392 Class<?>[] cs = null;
393 for (int imax = ts.length, i = 0; i < imax; i++) {
394 Class<?> c = canonicalize(ts[i], how);
395 if (c == void.class)
396 c = null; // a Void parameter was unwrapped to void; ignore
397 if (c != null) {
398 if (cs == null)
399 cs = ts.clone();
400 cs[i] = c;
401 }
402 }
403 return cs;
404 }
405
406 @Override
407 public String toString() {
408 return "Form"+erasedType;
409 }
410
411 }