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_GWT = 16, // guardWithTest
83 LF_LIMIT = 17;
84
85 /** Return the type corresponding uniquely (1-1) to this MT-form.
86 * It might have any primitive returns or arguments, but will have no references except Object.
87 */
88 public MethodType erasedType() {
89 return erasedType;
90 }
91
92 /** Return the basic type derived from the erased type of this MT-form.
93 * A basic type is erased (all references Object) and also has all primitive
94 * types (except int, long, float, double, void) normalized to int.
95 * Such basic types correspond to low-level JVM calling sequences.
96 */
97 public MethodType basicType() {
98 return basicType;
99 }
100
101 private boolean assertIsBasicType() {
102 // primitives must be flattened also
103 assert(erasedType == basicType)
104 : "erasedType: " + erasedType + " != basicType: " + basicType;
105 return true;
106 }
107
108 public MethodHandle cachedMethodHandle(int which) {
109 assert(assertIsBasicType());
110 return methodHandles[which];
111 }
112
113 synchronized public MethodHandle setCachedMethodHandle(int which, MethodHandle mh) {
114 // Simulate a CAS, to avoid racy duplication of results.
115 MethodHandle prev = methodHandles[which];
116 if (prev != null) return prev;
117 return methodHandles[which] = mh;
118 }
119
120 public LambdaForm cachedLambdaForm(int which) {
121 assert(assertIsBasicType());
122 return lambdaForms[which];
123 }
124
125 synchronized public LambdaForm setCachedLambdaForm(int which, LambdaForm form) {
126 // Simulate a CAS, to avoid racy duplication of results.
127 LambdaForm prev = lambdaForms[which];
128 if (prev != null) return prev;
129 return lambdaForms[which] = form;
130 }
131
132 /**
133 * Build an MTF for a given type, which must have all references erased to Object.
134 * This MTF will stand for that type and all un-erased variations.
135 * Eagerly compute some basic properties of the type, common to all variations.
136 */
137 protected MethodTypeForm(MethodType erasedType) {
138 this.erasedType = erasedType;
139
140 Class<?>[] ptypes = erasedType.ptypes();
141 int ptypeCount = ptypes.length;
142 int pslotCount = ptypeCount; // temp. estimate
143 int rtypeCount = 1; // temp. estimate
144 int rslotCount = 1; // temp. estimate
145
146 int[] argToSlotTab = null, slotToArgTab = null;
147
148 // Walk the argument types, looking for primitives.
149 int pac = 0, lac = 0, prc = 0, lrc = 0;
150 Class<?>[] epts = ptypes;
151 Class<?>[] bpts = epts;
152 for (int i = 0; i < epts.length; i++) {
153 Class<?> pt = epts[i];
154 if (pt != Object.class) {
155 ++pac;
156 Wrapper w = Wrapper.forPrimitiveType(pt);
157 if (w.isDoubleWord()) ++lac;
158 if (w.isSubwordOrInt() && pt != int.class) {
159 if (bpts == epts)
160 bpts = bpts.clone();
161 bpts[i] = int.class;
162 }
163 }
164 }
165 pslotCount += lac; // #slots = #args + #longs
166 Class<?> rt = erasedType.returnType();
167 Class<?> bt = rt;
168 if (rt != Object.class) {
169 ++prc; // even void.class counts as a prim here
170 Wrapper w = Wrapper.forPrimitiveType(rt);
171 if (w.isDoubleWord()) ++lrc;
172 if (w.isSubwordOrInt() && rt != int.class)
173 bt = int.class;
174 // adjust #slots, #args
175 if (rt == void.class)
176 rtypeCount = rslotCount = 0;
177 else
178 rslotCount += lrc;
179 }
180 if (epts == bpts && bt == rt) {
181 this.basicType = erasedType;
182 } else {
183 this.basicType = MethodType.makeImpl(bt, bpts, true);
184 // fill in rest of data from the basic type:
185 MethodTypeForm that = this.basicType.form();
186 assert(this != that);
187 this.primCounts = that.primCounts;
188 this.argCounts = that.argCounts;
189 this.argToSlotTable = that.argToSlotTable;
190 this.slotToArgTable = that.slotToArgTable;
191 this.methodHandles = null;
192 this.lambdaForms = null;
193 return;
194 }
195 if (lac != 0) {
196 int slot = ptypeCount + lac;
197 slotToArgTab = new int[slot+1];
198 argToSlotTab = new int[1+ptypeCount];
199 argToSlotTab[0] = slot; // argument "-1" is past end of slots
200 for (int i = 0; i < epts.length; i++) {
201 Class<?> pt = epts[i];
202 Wrapper w = Wrapper.forBasicType(pt);
203 if (w.isDoubleWord()) --slot;
204 --slot;
205 slotToArgTab[slot] = i+1; // "+1" see argSlotToParameter note
206 argToSlotTab[1+i] = slot;
207 }
208 assert(slot == 0); // filled the table
209 } else if (pac != 0) {
210 // have primitives but no long primitives; share slot counts with generic
211 assert(ptypeCount == pslotCount);
212 MethodTypeForm that = MethodType.genericMethodType(ptypeCount).form();
213 assert(this != that);
214 slotToArgTab = that.slotToArgTable;
215 argToSlotTab = that.argToSlotTable;
216 } else {
217 int slot = ptypeCount; // first arg is deepest in stack
218 slotToArgTab = new int[slot+1];
219 argToSlotTab = new int[1+ptypeCount];
220 argToSlotTab[0] = slot; // argument "-1" is past end of slots
221 for (int i = 0; i < ptypeCount; i++) {
222 --slot;
223 slotToArgTab[slot] = i+1; // "+1" see argSlotToParameter note
224 argToSlotTab[1+i] = slot;
225 }
226 }
227 this.primCounts = pack(lrc, prc, lac, pac);
228 this.argCounts = pack(rslotCount, rtypeCount, pslotCount, ptypeCount);
229 this.argToSlotTable = argToSlotTab;
230 this.slotToArgTable = slotToArgTab;
231
232 if (pslotCount >= 256) throw newIllegalArgumentException("too many arguments");
233
234 // Initialize caches, but only for basic types
235 assert(basicType == erasedType);
236 this.lambdaForms = new LambdaForm[LF_LIMIT];
237 this.methodHandles = new MethodHandle[MH_LIMIT];
238 }
239
240 private static long pack(int a, int b, int c, int d) {
241 assert(((a|b|c|d) & ~0xFFFF) == 0);
242 long hw = ((a << 16) | b), lw = ((c << 16) | d);
243 return (hw << 32) | lw;
244 }
245 private static char unpack(long packed, int word) { // word==0 => return a, ==3 => return d
246 assert(word <= 3);
247 return (char)(packed >> ((3-word) * 16));
248 }
249
250 public int parameterCount() { // # outgoing values
251 return unpack(argCounts, 3);
252 }
253 public int parameterSlotCount() { // # outgoing interpreter slots
254 return unpack(argCounts, 2);
255 }
256 public int returnCount() { // = 0 (V), or 1
257 return unpack(argCounts, 1);
258 }
259 public int returnSlotCount() { // = 0 (V), 2 (J/D), or 1
260 return unpack(argCounts, 0);
261 }
262 public int primitiveParameterCount() {
263 return unpack(primCounts, 3);
264 }
265 public int longPrimitiveParameterCount() {
266 return unpack(primCounts, 2);
267 }
268 public int primitiveReturnCount() { // = 0 (obj), or 1
269 return unpack(primCounts, 1);
270 }
271 public int longPrimitiveReturnCount() { // = 1 (J/D), or 0
272 return unpack(primCounts, 0);
273 }
274 public boolean hasPrimitives() {
275 return primCounts != 0;
276 }
277 public boolean hasNonVoidPrimitives() {
278 if (primCounts == 0) return false;
279 if (primitiveParameterCount() != 0) return true;
280 return (primitiveReturnCount() != 0 && returnCount() != 0);
281 }
282 public boolean hasLongPrimitives() {
283 return (longPrimitiveParameterCount() | longPrimitiveReturnCount()) != 0;
284 }
285 public int parameterToArgSlot(int i) {
286 return argToSlotTable[1+i];
287 }
288 public int argSlotToParameter(int argSlot) {
289 // Note: Empty slots are represented by zero in this table.
290 // Valid arguments slots contain incremented entries, so as to be non-zero.
291 // We return -1 the caller to mean an empty slot.
292 return slotToArgTable[argSlot] - 1;
293 }
294
295 static MethodTypeForm findForm(MethodType mt) {
296 MethodType erased = canonicalize(mt, ERASE, ERASE);
297 if (erased == null) {
298 // It is already erased. Make a new MethodTypeForm.
299 return new MethodTypeForm(mt);
300 } else {
301 // Share the MethodTypeForm with the erased version.
302 return erased.form();
303 }
304 }
305
306 /** Codes for {@link #canonicalize(java.lang.Class, int)}.
307 * ERASE means change every reference to {@code Object}.
308 * WRAP means convert primitives (including {@code void} to their
309 * corresponding wrapper types. UNWRAP means the reverse of WRAP.
310 * INTS means convert all non-void primitive types to int or long,
311 * according to size. LONGS means convert all non-void primitives
312 * to long, regardless of size. RAW_RETURN means convert a type
313 * (assumed to be a return type) to int if it is smaller than an int,
314 * or if it is void.
315 */
316 public static final int NO_CHANGE = 0, ERASE = 1, WRAP = 2, UNWRAP = 3, INTS = 4, LONGS = 5, RAW_RETURN = 6;
317
318 /** Canonicalize the types in the given method type.
319 * If any types change, intern the new type, and return it.
320 * Otherwise return null.
321 */
322 public static MethodType canonicalize(MethodType mt, int howRet, int howArgs) {
323 Class<?>[] ptypes = mt.ptypes();
324 Class<?>[] ptc = MethodTypeForm.canonicalizeAll(ptypes, howArgs);
325 Class<?> rtype = mt.returnType();
326 Class<?> rtc = MethodTypeForm.canonicalize(rtype, howRet);
327 if (ptc == null && rtc == null) {
328 // It is already canonical.
329 return null;
330 }
331 // Find the erased version of the method type:
332 if (rtc == null) rtc = rtype;
333 if (ptc == null) ptc = ptypes;
334 return MethodType.makeImpl(rtc, ptc, true);
335 }
336
337 /** Canonicalize the given return or param type.
338 * Return null if the type is already canonicalized.
339 */
340 static Class<?> canonicalize(Class<?> t, int how) {
341 Class<?> ct;
342 if (t == Object.class) {
343 // no change, ever
344 } else if (!t.isPrimitive()) {
345 switch (how) {
346 case UNWRAP:
347 ct = Wrapper.asPrimitiveType(t);
348 if (ct != t) return ct;
349 break;
350 case RAW_RETURN:
351 case ERASE:
352 return Object.class;
353 }
354 } else if (t == void.class) {
355 // no change, usually
356 switch (how) {
357 case RAW_RETURN:
358 return int.class;
359 case WRAP:
360 return Void.class;
361 }
362 } else {
363 // non-void primitive
364 switch (how) {
365 case WRAP:
366 return Wrapper.asWrapperType(t);
367 case INTS:
368 if (t == int.class || t == long.class)
369 return null; // no change
370 if (t == double.class)
371 return long.class;
372 return int.class;
373 case LONGS:
374 if (t == long.class)
375 return null; // no change
376 return long.class;
377 case RAW_RETURN:
378 if (t == int.class || t == long.class ||
379 t == float.class || t == double.class)
380 return null; // no change
381 // everything else returns as an int
382 return int.class;
383 }
384 }
385 // no change; return null to signify
386 return null;
387 }
388
389 /** Canonicalize each param type in the given array.
390 * Return null if all types are already canonicalized.
391 */
392 static Class<?>[] canonicalizeAll(Class<?>[] ts, int how) {
393 Class<?>[] cs = null;
394 for (int imax = ts.length, i = 0; i < imax; i++) {
395 Class<?> c = canonicalize(ts[i], how);
396 if (c == void.class)
397 c = null; // a Void parameter was unwrapped to void; ignore
398 if (c != null) {
399 if (cs == null)
400 cs = ts.clone();
401 cs[i] = c;
402 }
403 }
404 return cs;
405 }
406
407 @Override
408 public String toString() {
409 return "Form"+erasedType;
410 }
411
412 }