1 /*
2 * Copyright (c) 2014, 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 java.util.Arrays;
29 import static java.lang.invoke.LambdaForm.*;
30 import static java.lang.invoke.LambdaForm.BasicType.*;
31 import static java.lang.invoke.MethodHandleImpl.Intrinsic;
32 import java.util.Collections;
33 import java.util.concurrent.ConcurrentHashMap;
34
35 import sun.invoke.util.Wrapper;
36
37 /** Transforms on LFs.
38 * A lambda-form editor can derive new LFs from its base LF.
39 * The editor can cache derived LFs, which simplifies the reuse of their underlying bytecodes.
40 * To support this caching, a LF has an optional pointer to its editor.
41 */
42 class LambdaFormEditor {
43 final LambdaForm lambdaForm;
44
45 private LambdaFormEditor(LambdaForm lambdaForm) {
46 this.lambdaForm = lambdaForm;
47 }
48
49 // Factory method.
50 static LambdaFormEditor lambdaFormEditor(LambdaForm lambdaForm) {
51 // TO DO: Consider placing intern logic here, to cut down on duplication.
52 // lambdaForm = findPreexistingEquivalent(lambdaForm)
53 return new LambdaFormEditor(lambdaForm);
54 }
55
56 /** A description of a cached transform, possibly associated with the result of the transform.
57 * The logical content is a sequence of byte values, starting with a Kind.ordinal value.
58 * The sequence is unterminated, ending with an indefinite number of zero bytes.
59 * Sequences that are simple (short enough and with small enough values) pack into a 64-bit long.
60 */
61 private static final class Transform {
62 final long packedBytes;
63 final byte[] fullBytes;
64 final LambdaForm result; // result of transform, or null, if there is none available
65
66 private enum Kind {
67 NO_KIND, // necessary because ordinal must be greater than zero
68 BIND_ARG, ADD_ARG, DUP_ARG,
69 SPREAD_ARGS,
70 FILTER_ARG, FILTER_RETURN, FILTER_RETURN_TO_ZERO,
71 COLLECT_ARGS, COLLECT_ARGS_TO_VOID, COLLECT_ARGS_TO_ARRAY,
72 FOLD_ARGS, FOLD_ARGS_TO_VOID,
73 PERMUTE_ARGS
74 //maybe add more for guard with test, catch exception, pointwise type conversions
75 }
76
77 private static final boolean STRESS_TEST = false; // turn on to disable most packing
78 private static final int
79 PACKED_BYTE_SIZE = (STRESS_TEST ? 2 : 4),
80 PACKED_BYTE_MASK = (1 << PACKED_BYTE_SIZE) - 1,
81 PACKED_BYTE_MAX_LENGTH = (STRESS_TEST ? 3 : 64 / PACKED_BYTE_SIZE);
82
83 private static long packedBytes(byte[] bytes) {
84 if (bytes.length > PACKED_BYTE_MAX_LENGTH) return 0;
85 long pb = 0;
86 int bitset = 0;
87 for (int i = 0; i < bytes.length; i++) {
88 int b = bytes[i] & 0xFF;
89 bitset |= b;
90 pb |= (long)b << (i * PACKED_BYTE_SIZE);
91 }
92 if (!inRange(bitset))
93 return 0;
94 return pb;
95 }
96 private static long packedBytes(int b0, int b1) {
97 assert(inRange(b0 | b1));
98 return ( (b0 << 0*PACKED_BYTE_SIZE)
99 | (b1 << 1*PACKED_BYTE_SIZE));
100 }
101 private static long packedBytes(int b0, int b1, int b2) {
102 assert(inRange(b0 | b1 | b2));
103 return ( (b0 << 0*PACKED_BYTE_SIZE)
104 | (b1 << 1*PACKED_BYTE_SIZE)
105 | (b2 << 2*PACKED_BYTE_SIZE));
106 }
107 private static long packedBytes(int b0, int b1, int b2, int b3) {
108 assert(inRange(b0 | b1 | b2 | b3));
109 return ( (b0 << 0*PACKED_BYTE_SIZE)
110 | (b1 << 1*PACKED_BYTE_SIZE)
111 | (b2 << 2*PACKED_BYTE_SIZE)
112 | (b3 << 3*PACKED_BYTE_SIZE));
113 }
114 private static boolean inRange(int bitset) {
115 assert((bitset & 0xFF) == bitset); // incoming values must fit in *unsigned* byte
116 return ((bitset & ~PACKED_BYTE_MASK) == 0);
117 }
118 private static byte[] fullBytes(int... byteValues) {
119 byte[] bytes = new byte[byteValues.length];
120 int i = 0;
121 for (int bv : byteValues) {
122 bytes[i++] = bval(bv);
123 }
124 assert(packedBytes(bytes) == 0);
125 return bytes;
126 }
127
128 private byte byteAt(int i) {
129 long pb = packedBytes;
130 if (pb == 0) {
131 if (i >= fullBytes.length) return 0;
132 return fullBytes[i];
133 }
134 assert(fullBytes == null);
135 if (i > PACKED_BYTE_MAX_LENGTH) return 0;
136 int pos = (i * PACKED_BYTE_SIZE);
137 return (byte)((pb >>> pos) & PACKED_BYTE_MASK);
138 }
139
140 Kind kind() { return Kind.values()[byteAt(0)]; }
141
142 private Transform(long packedBytes, byte[] fullBytes, LambdaForm result) {
143 this.packedBytes = packedBytes;
144 this.fullBytes = fullBytes;
145 this.result = result;
146 }
147 private Transform(long packedBytes) {
148 this(packedBytes, null, null);
149 assert(packedBytes != 0);
150 }
151 private Transform(byte[] fullBytes) {
152 this(0, fullBytes, null);
153 }
154
155 private static byte bval(int b) {
156 assert((b & 0xFF) == b); // incoming value must fit in *unsigned* byte
157 return (byte)b;
158 }
159 private static byte bval(Kind k) {
160 return bval(k.ordinal());
161 }
162 static Transform of(Kind k, int b1) {
163 byte b0 = bval(k);
164 if (inRange(b0 | b1))
165 return new Transform(packedBytes(b0, b1));
166 else
167 return new Transform(fullBytes(b0, b1));
168 }
169 static Transform of(Kind k, int b1, int b2) {
170 byte b0 = (byte) k.ordinal();
171 if (inRange(b0 | b1 | b2))
172 return new Transform(packedBytes(b0, b1, b2));
173 else
174 return new Transform(fullBytes(b0, b1, b2));
175 }
176 static Transform of(Kind k, int b1, int b2, int b3) {
177 byte b0 = (byte) k.ordinal();
178 if (inRange(b0 | b1 | b2 | b3))
179 return new Transform(packedBytes(b0, b1, b2, b3));
180 else
181 return new Transform(fullBytes(b0, b1, b2, b3));
182 }
183 private static final byte[] NO_BYTES = {};
184 static Transform of(Kind k, int... b123) {
185 return ofBothArrays(k, b123, NO_BYTES);
186 }
187 static Transform of(Kind k, int b1, byte[] b234) {
188 return ofBothArrays(k, new int[]{ b1 }, b234);
189 }
190 static Transform of(Kind k, int b1, int b2, byte[] b345) {
191 return ofBothArrays(k, new int[]{ b1, b2 }, b345);
192 }
193 private static Transform ofBothArrays(Kind k, int[] b123, byte[] b456) {
194 byte[] fullBytes = new byte[1 + b123.length + b456.length];
195 int i = 0;
196 fullBytes[i++] = bval(k);
197 for (int bv : b123) {
198 fullBytes[i++] = bval(bv);
199 }
200 for (byte bv : b456) {
201 fullBytes[i++] = bv;
202 }
203 long packedBytes = packedBytes(fullBytes);
204 if (packedBytes != 0)
205 return new Transform(packedBytes);
206 else
207 return new Transform(fullBytes);
208 }
209
210 Transform withResult(LambdaForm result) {
211 return new Transform(this.packedBytes, this.fullBytes, result);
212 }
213
214 @Override
215 public boolean equals(Object obj) {
216 return obj instanceof Transform && equals((Transform)obj);
217 }
218 public boolean equals(Transform that) {
219 return this.packedBytes == that.packedBytes && Arrays.equals(this.fullBytes, that.fullBytes);
220 }
221 @Override
222 public int hashCode() {
223 if (packedBytes != 0) {
224 assert(fullBytes == null);
225 return Long.hashCode(packedBytes);
226 }
227 return Arrays.hashCode(fullBytes);
228 }
229 @Override
230 public String toString() {
231 StringBuilder buf = new StringBuilder();
232 long bits = packedBytes;
233 if (bits != 0) {
234 buf.append("(");
235 while (bits != 0) {
236 buf.append(bits & PACKED_BYTE_MASK);
237 bits >>>= PACKED_BYTE_SIZE;
238 if (bits != 0) buf.append(",");
239 }
240 buf.append(")");
241 }
242 if (fullBytes != null) {
243 buf.append("unpacked");
244 buf.append(Arrays.toString(fullBytes));
245 }
246 if (result != null) {
247 buf.append(" result=");
248 buf.append(result);
249 }
250 return buf.toString();
251 }
252 }
253
254 /** Find a previously cached transform equivalent to the given one, and return its result. */
255 private LambdaForm getInCache(Transform key) {
256 assert(key.result == null);
257 // The transformCache is one of null, Transform, Transform[], or ConcurrentHashMap.
258 Object c = lambdaForm.transformCache;
259 Transform k = null;
260 if (c instanceof ConcurrentHashMap) {
261 @SuppressWarnings("unchecked")
262 ConcurrentHashMap<Transform,Transform> m = (ConcurrentHashMap<Transform,Transform>) c;
263 k = m.get(key);
264 } else if (c == null) {
265 return null;
266 } else if (c instanceof Transform) {
267 // one-element cache avoids overhead of an array
268 Transform t = (Transform)c;
269 if (t.equals(key)) k = t;
270 } else {
271 Transform[] ta = (Transform[])c;
272 for (int i = 0; i < ta.length; i++) {
273 Transform t = ta[i];
274 if (t == null) break;
275 if (t.equals(key)) { k = t; break; }
276 }
277 }
278 assert(k == null || key.equals(k));
279 return k == null ? null : k.result;
280 }
281
282 /** Arbitrary but reasonable limits on Transform[] size for cache. */
283 private static final int MIN_CACHE_ARRAY_SIZE = 4, MAX_CACHE_ARRAY_SIZE = 16;
284
285 /** Cache a transform with its result, and return that result.
286 * But if an equivalent transform has already been cached, return its result instead.
287 */
288 private LambdaForm putInCache(Transform key, LambdaForm form) {
289 key = key.withResult(form);
290 for (int pass = 0; ; pass++) {
291 Object c = lambdaForm.transformCache;
292 if (c instanceof ConcurrentHashMap) {
293 @SuppressWarnings("unchecked")
294 ConcurrentHashMap<Transform,Transform> m = (ConcurrentHashMap<Transform,Transform>) c;
295 Transform k = m.putIfAbsent(key, key);
296 return k != null ? k.result : form;
297 }
298 assert(pass == 0);
299 synchronized (lambdaForm) {
300 c = lambdaForm.transformCache;
301 if (c instanceof ConcurrentHashMap)
302 continue;
303 if (c == null) {
304 lambdaForm.transformCache = key;
305 return form;
306 }
307 Transform[] ta;
308 if (c instanceof Transform) {
309 Transform k = (Transform)c;
310 if (k.equals(key)) {
311 return k.result;
312 }
313 // expand one-element cache to small array
314 ta = new Transform[MIN_CACHE_ARRAY_SIZE];
315 ta[0] = k;
316 lambdaForm.transformCache = c = ta;
317 } else {
318 // it is already expanded
319 ta = (Transform[])c;
320 }
321 int len = ta.length;
322 int i;
323 for (i = 0; i < len; i++) {
324 Transform k = ta[i];
325 if (k == null) {
326 break;
327 }
328 if (k.equals(key)) {
329 return k.result;
330 }
331 }
332 if (i < len) {
333 // just fall through to cache update
334 } else if (len < MAX_CACHE_ARRAY_SIZE) {
335 len = Math.min(len * 2, MAX_CACHE_ARRAY_SIZE);
336 ta = Arrays.copyOf(ta, len);
337 lambdaForm.transformCache = ta;
338 } else {
339 ConcurrentHashMap<Transform, Transform> m = new ConcurrentHashMap<>(MAX_CACHE_ARRAY_SIZE * 2);
340 for (Transform k : ta) {
341 m.put(k, k);
342 }
343 lambdaForm.transformCache = m;
344 // The second iteration will update for this query, concurrently.
345 continue;
346 }
347 ta[i] = key;
348 return form;
349 }
350 }
351 }
352
353 private LambdaFormBuffer buffer() {
354 return new LambdaFormBuffer(lambdaForm);
355 }
356
357 /// Editing methods for method handles. These need to have fast paths.
358
359 private BoundMethodHandle.SpeciesData oldSpeciesData() {
360 return BoundMethodHandle.speciesData(lambdaForm);
361 }
362 private BoundMethodHandle.SpeciesData newSpeciesData(BasicType type) {
363 return oldSpeciesData().extendWith(type);
364 }
365
366 BoundMethodHandle bindArgumentL(BoundMethodHandle mh, int pos, Object value) {
367 assert(mh.speciesData() == oldSpeciesData());
368 BasicType bt = L_TYPE;
369 MethodType type2 = bindArgumentType(mh, pos, bt);
370 LambdaForm form2 = bindArgumentForm(1+pos);
371 return mh.copyWithExtendL(type2, form2, value);
372 }
373 BoundMethodHandle bindArgumentI(BoundMethodHandle mh, int pos, int value) {
374 assert(mh.speciesData() == oldSpeciesData());
375 BasicType bt = I_TYPE;
376 MethodType type2 = bindArgumentType(mh, pos, bt);
377 LambdaForm form2 = bindArgumentForm(1+pos);
378 return mh.copyWithExtendI(type2, form2, value);
379 }
380
381 BoundMethodHandle bindArgumentJ(BoundMethodHandle mh, int pos, long value) {
382 assert(mh.speciesData() == oldSpeciesData());
383 BasicType bt = J_TYPE;
384 MethodType type2 = bindArgumentType(mh, pos, bt);
385 LambdaForm form2 = bindArgumentForm(1+pos);
386 return mh.copyWithExtendJ(type2, form2, value);
387 }
388
389 BoundMethodHandle bindArgumentF(BoundMethodHandle mh, int pos, float value) {
390 assert(mh.speciesData() == oldSpeciesData());
391 BasicType bt = F_TYPE;
392 MethodType type2 = bindArgumentType(mh, pos, bt);
393 LambdaForm form2 = bindArgumentForm(1+pos);
394 return mh.copyWithExtendF(type2, form2, value);
395 }
396
397 BoundMethodHandle bindArgumentD(BoundMethodHandle mh, int pos, double value) {
398 assert(mh.speciesData() == oldSpeciesData());
399 BasicType bt = D_TYPE;
400 MethodType type2 = bindArgumentType(mh, pos, bt);
401 LambdaForm form2 = bindArgumentForm(1+pos);
402 return mh.copyWithExtendD(type2, form2, value);
403 }
404
405 private MethodType bindArgumentType(BoundMethodHandle mh, int pos, BasicType bt) {
406 assert(mh.form == lambdaForm);
407 assert(mh.form.names[1+pos].type == bt);
408 assert(BasicType.basicType(mh.type().parameterType(pos)) == bt);
409 return mh.type().dropParameterTypes(pos, pos+1);
410 }
411
412 /// Editing methods for lambda forms.
413 // Each editing method can (potentially) cache the edited LF so that it can be reused later.
414
415 LambdaForm bindArgumentForm(int pos) {
416 Transform key = Transform.of(Transform.Kind.BIND_ARG, pos);
417 LambdaForm form = getInCache(key);
418 if (form != null) {
419 assert(form.parameterConstraint(0) == newSpeciesData(lambdaForm.parameterType(pos)));
420 return form;
421 }
422 LambdaFormBuffer buf = buffer();
423 buf.startEdit();
424
425 BoundMethodHandle.SpeciesData oldData = oldSpeciesData();
426 BoundMethodHandle.SpeciesData newData = newSpeciesData(lambdaForm.parameterType(pos));
427 Name oldBaseAddress = lambdaForm.parameter(0); // BMH holding the values
428 Name newBaseAddress;
429 NamedFunction getter = newData.getterFunction(oldData.fieldCount());
430
431 if (pos != 0) {
432 // The newly created LF will run with a different BMH.
433 // Switch over any pre-existing BMH field references to the new BMH class.
434 buf.replaceFunctions(oldData.getterFunctions(), newData.getterFunctions(), oldBaseAddress);
435 newBaseAddress = oldBaseAddress.withConstraint(newData);
436 buf.renameParameter(0, newBaseAddress);
437 buf.replaceParameterByNewExpression(pos, new Name(getter, newBaseAddress));
438 } else {
439 // cannot bind the MH arg itself, unless oldData is empty
440 assert(oldData == BoundMethodHandle.SpeciesData.EMPTY);
441 newBaseAddress = new Name(L_TYPE).withConstraint(newData);
442 buf.replaceParameterByNewExpression(0, new Name(getter, newBaseAddress));
443 buf.insertParameter(0, newBaseAddress);
444 }
445
446 buf.endEdit();
447 form = buf.lambdaForm();
448 return putInCache(key, form);
449 }
450 }