1 /*
2 * Copyright (c) 2008, 2016, 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 jdk.internal.vm.annotation.Stable;
29 import sun.invoke.util.Wrapper;
30
31 import java.lang.ref.SoftReference;
32
33 import static java.lang.invoke.MethodHandleStatics.newIllegalArgumentException;
34
35 /**
36 * Shared information for a group of method types, which differ
37 * only by reference types, and therefore share a common erasure
38 * and wrapping.
39 * <p>
40 * For an empirical discussion of the structure of method types,
41 * see <a href="http://groups.google.com/group/jvm-languages/browse_thread/thread/ac9308ae74da9b7e/">
42 * the thread "Avoiding Boxing" on jvm-languages</a>.
43 * There are approximately 2000 distinct erased method types in the JDK.
44 * There are a little over 10 times that number of unerased types.
45 * No more than half of these are likely to be loaded at once.
46 * @author John Rose
47 */
48 final class MethodTypeForm {
49 final int[] argToSlotTable, slotToArgTable;
50 final long argCounts; // packed slot & value counts
51 final long primCounts; // packed prim & double counts
52 final MethodType erasedType; // the canonical erasure
53 final MethodType basicType; // the canonical erasure, with primitives simplified
54
55 // Cached adapter information:
56 @Stable final SoftReference<MethodHandle>[] methodHandles;
57 // Indexes into methodHandles:
58 static final int
59 MH_BASIC_INV = 0, // cached instance of MH.invokeBasic
60 MH_NF_INV = 1, // cached helper for LF.NamedFunction
61 MH_UNINIT_CS = 2, // uninitialized call site
62 MH_LIMIT = 3;
63
64 // Cached lambda form information, for basic types only:
65 final @Stable SoftReference<LambdaForm>[] lambdaForms;
66 // Indexes into lambdaForms:
67 static final int
68 LF_INVVIRTUAL = 0, // DMH invokeVirtual
69 LF_INVSTATIC = 1,
70 LF_INVSPECIAL = 2,
71 LF_NEWINVSPECIAL = 3,
72 LF_INVINTERFACE = 4,
73 LF_INVSTATIC_INIT = 5, // DMH invokeStatic with <clinit> barrier
74 LF_INTERPRET = 6, // LF interpreter
75 LF_REBIND = 7, // BoundMethodHandle
76 LF_DELEGATE = 8, // DelegatingMethodHandle
77 LF_DELEGATE_BLOCK_INLINING = 9, // Counting DelegatingMethodHandle w/ @DontInline
78 LF_EX_LINKER = 10, // invokeExact_MT (for invokehandle)
79 LF_EX_INVOKER = 11, // MHs.invokeExact
80 LF_GEN_LINKER = 12, // generic invoke_MT (for invokehandle)
81 LF_GEN_INVOKER = 13, // generic MHs.invoke
82 LF_CS_LINKER = 14, // linkToCallSite_CS
83 LF_MH_LINKER = 15, // linkToCallSite_MH
84 LF_GWC = 16, // guardWithCatch (catchException)
85 LF_GWT = 17, // guardWithTest
86 LF_TF = 18, // tryFinally
87 LF_LOOP = 19, // loop
88 LF_LIMIT = 20;
89
90 /** Return the type corresponding uniquely (1-1) to this MT-form.
91 * It might have any primitive returns or arguments, but will have no references except Object.
92 */
93 public MethodType erasedType() {
94 return erasedType;
95 }
96
97 /** Return the basic type derived from the erased type of this MT-form.
98 * A basic type is erased (all references Object) and also has all primitive
99 * types (except int, long, float, double, void) normalized to int.
100 * Such basic types correspond to low-level JVM calling sequences.
101 */
102 public MethodType basicType() {
103 return basicType;
104 }
105
106 private boolean assertIsBasicType() {
107 // primitives must be flattened also
108 assert(erasedType == basicType)
109 : "erasedType: " + erasedType + " != basicType: " + basicType;
110 return true;
111 }
112
113 public MethodHandle cachedMethodHandle(int which) {
114 assert(assertIsBasicType());
115 SoftReference<MethodHandle> entry = methodHandles[which];
116 return (entry != null) ? entry.get() : null;
117 }
118
119 public synchronized MethodHandle setCachedMethodHandle(int which, MethodHandle mh) {
120 // Simulate a CAS, to avoid racy duplication of results.
121 SoftReference<MethodHandle> entry = methodHandles[which];
122 if (entry != null) {
123 MethodHandle prev = entry.get();
124 if (prev != null) {
125 return prev;
126 }
127 }
128 methodHandles[which] = new SoftReference<>(mh);
129 return mh;
130 }
131
132 public LambdaForm cachedLambdaForm(int which) {
133 assert(assertIsBasicType());
134 SoftReference<LambdaForm> entry = lambdaForms[which];
135 return (entry != null) ? entry.get() : null;
136 }
137
138 public synchronized LambdaForm setCachedLambdaForm(int which, LambdaForm form) {
139 // Simulate a CAS, to avoid racy duplication of results.
140 SoftReference<LambdaForm> entry = lambdaForms[which];
141 if (entry != null) {
142 LambdaForm prev = entry.get();
143 if (prev != null) {
144 return prev;
145 }
146 }
147 lambdaForms[which] = new SoftReference<>(form);
148 return form;
149 }
150
151 /**
152 * Build an MTF for a given type, which must have all references erased to Object.
153 * This MTF will stand for that type and all un-erased variations.
154 * Eagerly compute some basic properties of the type, common to all variations.
155 */
156 @SuppressWarnings({"rawtypes", "unchecked"})
157 protected MethodTypeForm(MethodType erasedType) {
158 this.erasedType = erasedType;
159
160 Class<?>[] ptypes = erasedType.ptypes();
161 int ptypeCount = ptypes.length;
162 int pslotCount = ptypeCount; // temp. estimate
163 int rtypeCount = 1; // temp. estimate
164 int rslotCount = 1; // temp. estimate
165
166 int[] argToSlotTab = null, slotToArgTab = null;
167
168 // Walk the argument types, looking for primitives.
169 int pac = 0, lac = 0, prc = 0, lrc = 0;
170 Class<?>[] epts = ptypes;
171 Class<?>[] bpts = epts;
172 for (int i = 0; i < epts.length; i++) {
173 Class<?> pt = epts[i];
174 if (pt != Object.class) {
175 ++pac;
176 Wrapper w = Wrapper.forPrimitiveType(pt);
177 if (w.isDoubleWord()) ++lac;
178 if (w.isSubwordOrInt() && pt != int.class) {
179 if (bpts == epts)
180 bpts = bpts.clone();
181 bpts[i] = int.class;
182 }
183 }
184 }
185 pslotCount += lac; // #slots = #args + #longs
186 Class<?> rt = erasedType.returnType();
187 Class<?> bt = rt;
188 if (rt != Object.class) {
189 ++prc; // even void.class counts as a prim here
190 Wrapper w = Wrapper.forPrimitiveType(rt);
191 if (w.isDoubleWord()) ++lrc;
192 if (w.isSubwordOrInt() && rt != int.class)
193 bt = int.class;
194 // adjust #slots, #args
195 if (rt == void.class)
196 rtypeCount = rslotCount = 0;
197 else
198 rslotCount += lrc;
199 }
200 if (epts == bpts && bt == rt) {
201 this.basicType = erasedType;
202 } else {
203 this.basicType = MethodType.makeImpl(bt, bpts, true);
204 // fill in rest of data from the basic type:
205 MethodTypeForm that = this.basicType.form();
206 assert(this != that);
207 this.primCounts = that.primCounts;
208 this.argCounts = that.argCounts;
209 this.argToSlotTable = that.argToSlotTable;
210 this.slotToArgTable = that.slotToArgTable;
211 this.methodHandles = null;
212 this.lambdaForms = null;
213 return;
214 }
215 if (lac != 0) {
216 int slot = ptypeCount + lac;
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 < epts.length; i++) {
221 Class<?> pt = epts[i];
222 Wrapper w = Wrapper.forBasicType(pt);
223 if (w.isDoubleWord()) --slot;
224 --slot;
225 slotToArgTab[slot] = i+1; // "+1" see argSlotToParameter note
226 argToSlotTab[1+i] = slot;
227 }
228 assert(slot == 0); // filled the table
229 } else if (pac != 0) {
230 // have primitives but no long primitives; share slot counts with generic
231 assert(ptypeCount == pslotCount);
232 MethodTypeForm that = MethodType.genericMethodType(ptypeCount).form();
233 assert(this != that);
234 slotToArgTab = that.slotToArgTable;
235 argToSlotTab = that.argToSlotTable;
236 } else {
237 int slot = ptypeCount; // first arg is deepest in stack
238 slotToArgTab = new int[slot+1];
239 argToSlotTab = new int[1+ptypeCount];
240 argToSlotTab[0] = slot; // argument "-1" is past end of slots
241 for (int i = 0; i < ptypeCount; i++) {
242 --slot;
243 slotToArgTab[slot] = i+1; // "+1" see argSlotToParameter note
244 argToSlotTab[1+i] = slot;
245 }
246 }
247 this.primCounts = pack(lrc, prc, lac, pac);
248 this.argCounts = pack(rslotCount, rtypeCount, pslotCount, ptypeCount);
249 this.argToSlotTable = argToSlotTab;
250 this.slotToArgTable = slotToArgTab;
251
252 if (pslotCount >= 256) throw newIllegalArgumentException("too many arguments");
253
254 // Initialize caches, but only for basic types
255 assert(basicType == erasedType);
256 this.lambdaForms = new SoftReference[LF_LIMIT];
257 this.methodHandles = new SoftReference[MH_LIMIT];
258 }
259
260 private static long pack(int a, int b, int c, int d) {
261 assert(((a|b|c|d) & ~0xFFFF) == 0);
262 long hw = ((a << 16) | b), lw = ((c << 16) | d);
263 return (hw << 32) | lw;
264 }
265 private static char unpack(long packed, int word) { // word==0 => return a, ==3 => return d
266 assert(word <= 3);
267 return (char)(packed >> ((3-word) * 16));
268 }
269
270 public int parameterCount() { // # outgoing values
271 return unpack(argCounts, 3);
272 }
273 public int parameterSlotCount() { // # outgoing interpreter slots
274 return unpack(argCounts, 2);
275 }
276 public int returnCount() { // = 0 (V), or 1
277 return unpack(argCounts, 1);
278 }
279 public int returnSlotCount() { // = 0 (V), 2 (J/D), or 1
280 return unpack(argCounts, 0);
281 }
282 public int primitiveParameterCount() {
283 return unpack(primCounts, 3);
284 }
285 public int longPrimitiveParameterCount() {
286 return unpack(primCounts, 2);
287 }
288 public int primitiveReturnCount() { // = 0 (obj), or 1
289 return unpack(primCounts, 1);
290 }
291 public int longPrimitiveReturnCount() { // = 1 (J/D), or 0
292 return unpack(primCounts, 0);
293 }
294 public boolean hasPrimitives() {
295 return primCounts != 0;
296 }
297 public boolean hasNonVoidPrimitives() {
298 if (primCounts == 0) return false;
299 if (primitiveParameterCount() != 0) return true;
300 return (primitiveReturnCount() != 0 && returnCount() != 0);
301 }
302 public boolean hasLongPrimitives() {
303 return (longPrimitiveParameterCount() | longPrimitiveReturnCount()) != 0;
304 }
305 public int parameterToArgSlot(int i) {
306 return argToSlotTable[1+i];
307 }
308 public int argSlotToParameter(int argSlot) {
309 // Note: Empty slots are represented by zero in this table.
310 // Valid arguments slots contain incremented entries, so as to be non-zero.
311 // We return -1 the caller to mean an empty slot.
312 return slotToArgTable[argSlot] - 1;
313 }
314
315 static MethodTypeForm findForm(MethodType mt) {
316 MethodType erased = canonicalize(mt, ERASE, ERASE);
317 if (erased == null) {
318 // It is already erased. Make a new MethodTypeForm.
319 return new MethodTypeForm(mt);
320 } else {
321 // Share the MethodTypeForm with the erased version.
322 return erased.form();
323 }
324 }
325
326 /** Codes for {@link #canonicalize(java.lang.Class, int)}.
327 * ERASE means change every reference to {@code Object}.
328 * WRAP means convert primitives (including {@code void} to their
329 * corresponding wrapper types. UNWRAP means the reverse of WRAP.
330 * INTS means convert all non-void primitive types to int or long,
331 * according to size. LONGS means convert all non-void primitives
332 * to long, regardless of size. RAW_RETURN means convert a type
333 * (assumed to be a return type) to int if it is smaller than an int,
334 * or if it is void.
335 */
336 public static final int NO_CHANGE = 0, ERASE = 1, WRAP = 2, UNWRAP = 3, INTS = 4, LONGS = 5, RAW_RETURN = 6;
337
338 /** Canonicalize the types in the given method type.
339 * If any types change, intern the new type, and return it.
340 * Otherwise return null.
341 */
342 public static MethodType canonicalize(MethodType mt, int howRet, int howArgs) {
343 Class<?>[] ptypes = mt.ptypes();
344 Class<?>[] ptc = MethodTypeForm.canonicalizeAll(ptypes, howArgs);
345 Class<?> rtype = mt.returnType();
346 Class<?> rtc = MethodTypeForm.canonicalize(rtype, howRet);
347 if (ptc == null && rtc == null) {
348 // It is already canonical.
349 return null;
350 }
351 // Find the erased version of the method type:
352 if (rtc == null) rtc = rtype;
353 if (ptc == null) ptc = ptypes;
354 return MethodType.makeImpl(rtc, ptc, true);
355 }
356
357 /** Canonicalize the given return or param type.
358 * Return null if the type is already canonicalized.
359 */
360 static Class<?> canonicalize(Class<?> t, int how) {
361 Class<?> ct;
362 if (t == Object.class) {
363 // no change, ever
364 } else if (!t.isPrimitive()) {
365 switch (how) {
366 case UNWRAP:
367 ct = Wrapper.asPrimitiveType(t);
368 if (ct != t) return ct;
369 break;
370 case RAW_RETURN:
371 case ERASE:
372 return Object.class;
373 }
374 } else if (t == void.class) {
375 // no change, usually
376 switch (how) {
377 case RAW_RETURN:
378 return int.class;
379 case WRAP:
380 return Void.class;
381 }
382 } else {
383 // non-void primitive
384 switch (how) {
385 case WRAP:
386 return Wrapper.asWrapperType(t);
387 case INTS:
388 if (t == int.class || t == long.class)
389 return null; // no change
390 if (t == double.class)
391 return long.class;
392 return int.class;
393 case LONGS:
394 if (t == long.class)
395 return null; // no change
396 return long.class;
397 case RAW_RETURN:
398 if (t == int.class || t == long.class ||
399 t == float.class || t == double.class)
400 return null; // no change
401 // everything else returns as an int
402 return int.class;
403 }
404 }
405 // no change; return null to signify
406 return null;
407 }
408
409 /** Canonicalize each param type in the given array.
410 * Return null if all types are already canonicalized.
411 */
412 static Class<?>[] canonicalizeAll(Class<?>[] ts, int how) {
413 Class<?>[] cs = null;
414 for (int imax = ts.length, i = 0; i < imax; i++) {
415 Class<?> c = canonicalize(ts[i], how);
416 if (c == void.class)
417 c = null; // a Void parameter was unwrapped to void; ignore
418 if (c != null) {
419 if (cs == null)
420 cs = ts.clone();
421 cs[i] = c;
422 }
423 }
424 return cs;
425 }
426
427 @Override
428 public String toString() {
429 return "Form"+erasedType;
430 }
431 }