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 java.lang.ref.SoftReference;
30 import static java.lang.invoke.MethodHandleStatics.*;
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 MethodType erasedType; // the canonical erasure
50 final MethodType basicType; // the canonical erasure, with primitives simplified
51
52 // Cached adapter information:
53 @Stable final SoftReference<MethodHandle>[] methodHandles;
54 // Indexes into methodHandles:
55 static final int
56 MH_BASIC_INV = 0, // cached instance of MH.invokeBasic
57 MH_NF_INV = 1, // cached helper for LF.NamedFunction
58 MH_UNINIT_CS = 2, // uninitialized call site
59 MH_LIMIT = 3;
60
61 // Cached lambda form information, for basic types only:
62 final @Stable SoftReference<LambdaForm>[] lambdaForms;
63 // Indexes into lambdaForms:
64 static final int
65 LF_INVVIRTUAL = 0, // DMH invokeVirtual
66 LF_INVSTATIC = 1,
67 LF_INVSPECIAL = 2,
68 LF_NEWINVSPECIAL = 3,
69 LF_INVINTERFACE = 4,
70 LF_INVSTATIC_INIT = 5, // DMH invokeStatic with <clinit> barrier
71 LF_INTERPRET = 6, // LF interpreter
72 LF_REBIND = 7, // BoundMethodHandle
73 LF_DELEGATE = 8, // DelegatingMethodHandle
74 LF_DELEGATE_BLOCK_INLINING = 9, // Counting DelegatingMethodHandle w/ @DontInline
75 LF_EX_LINKER = 10, // invokeExact_MT (for invokehandle)
76 LF_EX_INVOKER = 11, // MHs.invokeExact
77 LF_GEN_LINKER = 12, // generic invoke_MT (for invokehandle)
78 LF_GEN_INVOKER = 13, // generic MHs.invoke
79 LF_CS_LINKER = 14, // linkToCallSite_CS
80 LF_MH_LINKER = 15, // linkToCallSite_MH
81 LF_GWC = 16, // guardWithCatch (catchException)
82 LF_GWT = 17, // guardWithTest
83 LF_LIMIT = 18;
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 SoftReference<MethodHandle> entry = methodHandles[which];
111 return (entry != null) ? entry.get() : null;
112 }
113
114 synchronized public MethodHandle setCachedMethodHandle(int which, MethodHandle mh) {
115 // Simulate a CAS, to avoid racy duplication of results.
116 SoftReference<MethodHandle> entry = methodHandles[which];
117 if (entry != null) {
118 MethodHandle prev = entry.get();
119 if (prev != null) {
120 return prev;
121 }
122 }
123 methodHandles[which] = new SoftReference<>(mh);
124 return mh;
125 }
126
127 public LambdaForm cachedLambdaForm(int which) {
128 assert(assertIsBasicType());
129 SoftReference<LambdaForm> entry = lambdaForms[which];
130 return (entry != null) ? entry.get() : null;
131 }
132
133 synchronized public LambdaForm setCachedLambdaForm(int which, LambdaForm form) {
134 // Simulate a CAS, to avoid racy duplication of results.
135 SoftReference<LambdaForm> entry = lambdaForms[which];
136 if (entry != null) {
137 LambdaForm prev = entry.get();
138 if (prev != null) {
139 return prev;
140 }
141 }
142 lambdaForms[which] = new SoftReference<>(form);
143 return form;
144 }
145
146 /**
147 * Build an MTF for a given type, which must have all references erased to Object.
148 * This MTF will stand for that type and all un-erased variations.
149 * Eagerly compute some basic properties of the type, common to all variations.
150 */
151 @SuppressWarnings({"rawtypes", "unchecked"})
152 protected MethodTypeForm(MethodType erasedType) {
153 this.erasedType = erasedType;
154
155 Class<?>[] ptypes = erasedType.ptypes();
156 int ptypeCount = ptypes.length;
157 int pslotCount = ptypeCount; // temp. estimate
158 int rtypeCount = 1; // temp. estimate
159 int rslotCount = 1; // temp. estimate
160
161 int[] argToSlotTab = null, slotToArgTab = null;
162
163 // Walk the argument types, looking for primitives.
164 int pac = 0, lac = 0, prc = 0, lrc = 0;
165 Class<?>[] epts = ptypes;
166 Class<?>[] bpts = epts;
167 for (int i = 0; i < epts.length; i++) {
168 Class<?> pt = epts[i];
169 if (pt != Object.class) {
170 ++pac;
171 Wrapper w = Wrapper.forPrimitiveType(pt);
172 if (w.isDoubleWord()) ++lac;
173 if (w.isSubwordOrInt() && pt != int.class) {
174 if (bpts == epts)
175 bpts = bpts.clone();
176 bpts[i] = int.class;
177 }
178 }
179 }
180 pslotCount += lac; // #slots = #args + #longs
181 Class<?> rt = erasedType.returnType();
182 Class<?> bt = rt;
183 if (rt != Object.class) {
184 ++prc; // even void.class counts as a prim here
185 Wrapper w = Wrapper.forPrimitiveType(rt);
186 if (w.isDoubleWord()) ++lrc;
187 if (w.isSubwordOrInt() && rt != int.class)
188 bt = int.class;
189 // adjust #slots, #args
190 if (rt == void.class)
191 rtypeCount = rslotCount = 0;
192 else
193 rslotCount += lrc;
194 }
195 if (epts == bpts && bt == rt) {
196 this.basicType = erasedType;
197 } else {
198 this.basicType = MethodType.makeImpl(bt, bpts, true);
199 // fill in rest of data from the basic type:
200 MethodTypeForm that = this.basicType.form();
201 assert(this != that);
202 this.primCounts = that.primCounts;
203 this.argCounts = that.argCounts;
204 this.argToSlotTable = that.argToSlotTable;
205 this.slotToArgTable = that.slotToArgTable;
206 this.methodHandles = null;
207 this.lambdaForms = null;
208 return;
209 }
210 if (lac != 0) {
211 int slot = ptypeCount + lac;
212 slotToArgTab = new int[slot+1];
213 argToSlotTab = new int[1+ptypeCount];
214 argToSlotTab[0] = slot; // argument "-1" is past end of slots
215 for (int i = 0; i < epts.length; i++) {
216 Class<?> pt = epts[i];
217 Wrapper w = Wrapper.forBasicType(pt);
218 if (w.isDoubleWord()) --slot;
219 --slot;
220 slotToArgTab[slot] = i+1; // "+1" see argSlotToParameter note
221 argToSlotTab[1+i] = slot;
222 }
223 assert(slot == 0); // filled the table
224 } else if (pac != 0) {
225 // have primitives but no long primitives; share slot counts with generic
226 assert(ptypeCount == pslotCount);
227 MethodTypeForm that = MethodType.genericMethodType(ptypeCount).form();
228 assert(this != that);
229 slotToArgTab = that.slotToArgTable;
230 argToSlotTab = that.argToSlotTable;
231 } else {
232 int slot = ptypeCount; // first arg is deepest in stack
233 slotToArgTab = new int[slot+1];
234 argToSlotTab = new int[1+ptypeCount];
235 argToSlotTab[0] = slot; // argument "-1" is past end of slots
236 for (int i = 0; i < ptypeCount; i++) {
237 --slot;
238 slotToArgTab[slot] = i+1; // "+1" see argSlotToParameter note
239 argToSlotTab[1+i] = slot;
240 }
241 }
242 this.primCounts = pack(lrc, prc, lac, pac);
243 this.argCounts = pack(rslotCount, rtypeCount, pslotCount, ptypeCount);
244 this.argToSlotTable = argToSlotTab;
245 this.slotToArgTable = slotToArgTab;
246
247 if (pslotCount >= 256) throw newIllegalArgumentException("too many arguments");
248
249 // Initialize caches, but only for basic types
250 assert(basicType == erasedType);
251 this.lambdaForms = new SoftReference[LF_LIMIT];
252 this.methodHandles = new SoftReference[MH_LIMIT];
253 }
254
255 private static long pack(int a, int b, int c, int d) {
256 assert(((a|b|c|d) & ~0xFFFF) == 0);
257 long hw = ((a << 16) | b), lw = ((c << 16) | d);
258 return (hw << 32) | lw;
259 }
260 private static char unpack(long packed, int word) { // word==0 => return a, ==3 => return d
261 assert(word <= 3);
262 return (char)(packed >> ((3-word) * 16));
263 }
264
265 public int parameterCount() { // # outgoing values
266 return unpack(argCounts, 3);
267 }
268 public int parameterSlotCount() { // # outgoing interpreter slots
269 return unpack(argCounts, 2);
270 }
271 public int returnCount() { // = 0 (V), or 1
272 return unpack(argCounts, 1);
273 }
274 public int returnSlotCount() { // = 0 (V), 2 (J/D), or 1
275 return unpack(argCounts, 0);
276 }
277 public int primitiveParameterCount() {
278 return unpack(primCounts, 3);
279 }
280 public int longPrimitiveParameterCount() {
281 return unpack(primCounts, 2);
282 }
283 public int primitiveReturnCount() { // = 0 (obj), or 1
284 return unpack(primCounts, 1);
285 }
286 public int longPrimitiveReturnCount() { // = 1 (J/D), or 0
287 return unpack(primCounts, 0);
288 }
289 public boolean hasPrimitives() {
290 return primCounts != 0;
291 }
292 public boolean hasNonVoidPrimitives() {
293 if (primCounts == 0) return false;
294 if (primitiveParameterCount() != 0) return true;
295 return (primitiveReturnCount() != 0 && returnCount() != 0);
296 }
297 public boolean hasLongPrimitives() {
298 return (longPrimitiveParameterCount() | longPrimitiveReturnCount()) != 0;
299 }
300 public int parameterToArgSlot(int i) {
301 return argToSlotTable[1+i];
302 }
303 public int argSlotToParameter(int argSlot) {
304 // Note: Empty slots are represented by zero in this table.
305 // Valid arguments slots contain incremented entries, so as to be non-zero.
306 // We return -1 the caller to mean an empty slot.
307 return slotToArgTable[argSlot] - 1;
308 }
309
310 static MethodTypeForm findForm(MethodType mt) {
311 MethodType erased = canonicalize(mt, ERASE, ERASE);
312 if (erased == null) {
313 // It is already erased. Make a new MethodTypeForm.
314 return new MethodTypeForm(mt);
315 } else {
316 // Share the MethodTypeForm with the erased version.
317 return erased.form();
318 }
319 }
320
321 /** Codes for {@link #canonicalize(java.lang.Class, int)}.
322 * ERASE means change every reference to {@code Object}.
323 * WRAP means convert primitives (including {@code void} to their
324 * corresponding wrapper types. UNWRAP means the reverse of WRAP.
325 * INTS means convert all non-void primitive types to int or long,
326 * according to size. LONGS means convert all non-void primitives
327 * to long, regardless of size. RAW_RETURN means convert a type
328 * (assumed to be a return type) to int if it is smaller than an int,
329 * or if it is void.
330 */
331 public static final int NO_CHANGE = 0, ERASE = 1, WRAP = 2, UNWRAP = 3, INTS = 4, LONGS = 5, RAW_RETURN = 6;
332
333 /** Canonicalize the types in the given method type.
334 * If any types change, intern the new type, and return it.
335 * Otherwise return null.
336 */
337 public static MethodType canonicalize(MethodType mt, int howRet, int howArgs) {
338 Class<?>[] ptypes = mt.ptypes();
339 Class<?>[] ptc = MethodTypeForm.canonicalizeAll(ptypes, howArgs);
340 Class<?> rtype = mt.returnType();
341 Class<?> rtc = MethodTypeForm.canonicalize(rtype, howRet);
342 if (ptc == null && rtc == null) {
343 // It is already canonical.
344 return null;
345 }
346 // Find the erased version of the method type:
347 if (rtc == null) rtc = rtype;
348 if (ptc == null) ptc = ptypes;
349 return MethodType.makeImpl(rtc, ptc, true);
350 }
351
352 /** Canonicalize the given return or param type.
353 * Return null if the type is already canonicalized.
354 */
355 static Class<?> canonicalize(Class<?> t, int how) {
356 Class<?> ct;
357 if (t == Object.class) {
358 // no change, ever
359 } else if (!t.isPrimitive()) {
360 switch (how) {
361 case UNWRAP:
362 ct = Wrapper.asPrimitiveType(t);
363 if (ct != t) return ct;
364 break;
365 case RAW_RETURN:
366 case ERASE:
367 return Object.class;
368 }
369 } else if (t == void.class) {
370 // no change, usually
371 switch (how) {
372 case RAW_RETURN:
373 return int.class;
374 case WRAP:
375 return Void.class;
376 }
377 } else {
378 // non-void primitive
379 switch (how) {
380 case WRAP:
381 return Wrapper.asWrapperType(t);
382 case INTS:
383 if (t == int.class || t == long.class)
384 return null; // no change
385 if (t == double.class)
386 return long.class;
387 return int.class;
388 case LONGS:
389 if (t == long.class)
390 return null; // no change
391 return long.class;
392 case RAW_RETURN:
393 if (t == int.class || t == long.class ||
394 t == float.class || t == double.class)
395 return null; // no change
396 // everything else returns as an int
397 return int.class;
398 }
399 }
400 // no change; return null to signify
401 return null;
402 }
403
404 /** Canonicalize each param type in the given array.
405 * Return null if all types are already canonicalized.
406 */
407 static Class<?>[] canonicalizeAll(Class<?>[] ts, int how) {
408 Class<?>[] cs = null;
409 for (int imax = ts.length, i = 0; i < imax; i++) {
410 Class<?> c = canonicalize(ts[i], how);
411 if (c == void.class)
412 c = null; // a Void parameter was unwrapped to void; ignore
413 if (c != null) {
414 if (cs == null)
415 cs = ts.clone();
416 cs[i] = c;
417 }
418 }
419 return cs;
420 }
421
422 @Override
423 public String toString() {
424 return "Form"+erasedType;
425 }
426 }