1 /*
2 * Copyright (c) 2019, 2021, 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 com.sun.tools.javac.jvm;
27
28 import com.sun.tools.javac.code.Kinds.Kind;
29 import com.sun.tools.javac.code.Symbol;
30 import com.sun.tools.javac.code.Symbol.ClassSymbol;
31 import com.sun.tools.javac.code.Symbol.DynamicMethodSymbol;
32 import com.sun.tools.javac.code.Symbol.MethodHandleSymbol;
33 import com.sun.tools.javac.code.Symbol.ModuleSymbol;
34 import com.sun.tools.javac.code.Symbol.PackageSymbol;
35 import com.sun.tools.javac.code.Type;
36 import com.sun.tools.javac.code.Type.ConstantPoolQType;
37 import com.sun.tools.javac.code.Types;
38 import com.sun.tools.javac.jvm.ClassWriter.PoolOverflow;
39 import com.sun.tools.javac.jvm.ClassWriter.StringOverflow;
40 import com.sun.tools.javac.jvm.PoolConstant.LoadableConstant;
41 import com.sun.tools.javac.jvm.PoolConstant.LoadableConstant.BasicConstant;
42 import com.sun.tools.javac.jvm.PoolConstant.Dynamic;
43 import com.sun.tools.javac.jvm.PoolConstant.Dynamic.BsmKey;
44 import com.sun.tools.javac.jvm.PoolConstant.NameAndType;
45 import com.sun.tools.javac.util.ByteBuffer;
46 import com.sun.tools.javac.util.List;
47 import com.sun.tools.javac.util.Name;
48 import com.sun.tools.javac.util.Names;
49
50 import java.io.IOException;
51 import java.io.OutputStream;
52 import java.util.ArrayDeque;
53 import java.util.HashMap;
54 import java.util.HashSet;
55 import java.util.LinkedHashMap;
56 import java.util.LinkedHashSet;
57 import java.util.Map;
58 import java.util.Set;
59
60 import static com.sun.tools.javac.code.Kinds.Kind.TYP;
61 import static com.sun.tools.javac.code.TypeTag.ARRAY;
62 import static com.sun.tools.javac.code.TypeTag.CLASS;
63 import static com.sun.tools.javac.jvm.ClassFile.CONSTANT_Class;
64 import static com.sun.tools.javac.jvm.ClassFile.CONSTANT_MethodType;
65 import static com.sun.tools.javac.jvm.ClassFile.externalize;
66
67 /**
68 * Pool interface towards {@code ClassWriter}. Exposes methods to encode and write javac entities
69 * into the constant pool.
70 *
71 * <p><b>This is NOT part of any supported API.
72 * If you write code that depends on this, you do so at your own risk.
73 * This code and its internal interfaces are subject to change or
74 * deletion without notice.</b>
75 */
76 public class PoolWriter {
77
78 /** Max number of constant pool entries. */
79 public static final int MAX_ENTRIES = 0xFFFF;
80
81 /** Max number of char in a string constant. */
82 public static final int MAX_STRING_LENGTH = 0xFFFF;
83
84 private static final int POOL_BUF_SIZE = 0x7fff;
85
86 private final Types types;
87
88 private final Names names;
89
90 /** Pool helper **/
91 final WriteablePoolHelper pool;
92
93 /** Sole signature generator */
94 final SharedSignatureGenerator signatureGen;
95
96 /** The inner classes to be written, as an ordered set (enclosing first). */
97 LinkedHashSet<ClassSymbol> innerClasses = new LinkedHashSet<>();
98
99 Set<ClassSymbol> preloadClasses = new HashSet<>();
100
101 /** The list of entries in the BootstrapMethods attribute. */
102 Map<BsmKey, Integer> bootstrapMethods = new LinkedHashMap<>();
103
104 public PoolWriter(Types types, Names names) {
105 this.types = types;
106 this.names = names;
107 this.signatureGen = new SharedSignatureGenerator(types);
108 this.pool = new WriteablePoolHelper();
109 }
110
111 /**
112 * Puts a class symbol into the pool and return its index.
113 */
114 int putClass(ClassSymbol csym) {
115 return putClass(csym.type);
116 }
117
118 /**
119 * Puts a type into the pool and return its index. The type could be either a class, a type variable
120 * or an array type.
121 */
122 int putClass(Type t) {
123 /* Their is nothing to be gained by having the pair of class types Foo.ref and Foo.val
124 result in two different CONSTANT_Class_info strucures in the pool. These are
125 indistinguishable at the class file level. Hence we coalesce them here.
126 */
127 if (t.isReferenceProjection())
128 t = t.valueProjection();
129 return pool.writeIfNeeded(types.erasure(t));
130 }
131
132 /**
133 * Puts a type into the pool and return its index. The type could be either a class, a type variable
134 * or an array type.
135 */
136 int putClass(ConstantPoolQType t) {
137 return pool.writeIfNeeded(t);
138 }
139
140 /**
141 * Puts a member reference into the constant pool. Valid members are either field or method symbols.
142 */
143 int putMember(Symbol s) {
144 return pool.writeIfNeeded(s);
145 }
146
147 /**
148 * Puts a dynamic reference into the constant pool and return its index.
149 */
150 int putDynamic(Dynamic d) {
151 return pool.writeIfNeeded(d);
152 }
153
154 /**
155 * Puts a field or method descriptor into the constant pool and return its index.
156 */
157 int putDescriptor(Type t) {
158 return putName(typeSig(types.erasure(t)));
159 }
160
161 /**
162 * Puts a field or method descriptor into the constant pool and return its index.
163 */
164 int putDescriptor(Symbol s) {
165 return putDescriptor(descriptorType(s));
166 }
167
168 /**
169 * Puts a signature (see {@code Signature} attribute in JVMS 4.4) into the constant pool and
170 * return its index.
171 */
172 int putSignature(Symbol s) {
173 if (s.kind == TYP) {
174 return putName(classSig(s.type));
175 } else {
176 return putName(typeSig(s.type));
177 }
178 }
179
180 /**
181 * Puts a constant value into the pool and return its index. Supported values are int, float, long,
182 * double and String.
183 */
184 int putConstant(Object o) {
185 if (o instanceof Integer intVal) {
186 return putConstant(LoadableConstant.Int(intVal));
187 } else if (o instanceof Float floatVal) {
188 return putConstant(LoadableConstant.Float(floatVal));
189 } else if (o instanceof Long longVal) {
190 return putConstant(LoadableConstant.Long(longVal));
191 } else if (o instanceof Double doubleVal) {
192 return putConstant(LoadableConstant.Double(doubleVal));
193 } else if (o instanceof String strVal) {
194 return putConstant(LoadableConstant.String(strVal));
195 } else {
196 throw new AssertionError("unexpected constant: " + o);
197 }
198 }
199
200 /**
201 * Puts a constant into the pool and return its index.
202 */
203 int putConstant(LoadableConstant c) {
204 switch (c.poolTag()) {
205 case CONSTANT_Class:
206 return putClass((Type)c);
207 case CONSTANT_MethodType:
208 return pool.writeIfNeeded(types.erasure((Type)c));
209 default:
210 return pool.writeIfNeeded(c);
211 }
212 }
213
214 int putName(Name name) {
215 return pool.writeIfNeeded(name);
216 }
217
218 /**
219 * Puts a name and type pair into the pool and returns its index.
220 */
221 int putNameAndType(Symbol s) {
222 return pool.writeIfNeeded(new NameAndType(s.name, descriptorType(s)));
223 }
224
225 /**
226 * Puts a package entry into the pool and returns its index.
227 */
228 int putPackage(PackageSymbol pkg) {
229 return pool.writeIfNeeded(pkg);
230 }
231
232 /**
233 * Puts a module entry into the pool and returns its index.
234 */
235 int putModule(ModuleSymbol mod) {
236 return pool.writeIfNeeded(mod);
237 }
238
239 /**
240 * Enter an inner class into the `innerClasses' set.
241 */
242 void enterInnerClass(ClassSymbol c) {
243 if (c.type.isCompound()) {
244 throw new AssertionError("Unexpected intersection type: " + c.type);
245 }
246 c.complete();
247 if (c.owner.enclClass() != null && !innerClasses.contains(c)) {
248 enterInnerClass(c.owner.enclClass());
249 innerClasses.add(c);
250 }
251 }
252
253 /** Enter a value class into the `preloadClasses' set.
254 */
255 void enterPreloadClass(ClassSymbol c) {
256 if (c.type.isCompound()) {
257 throw new AssertionError("Unexpected intersection type: " + c.type);
258 }
259 c.complete();
260 preloadClasses.add(c);
261 }
262
263 /**
264 * Create a new Utf8 entry representing a descriptor for given (member) symbol.
265 */
266 private Type descriptorType(Symbol s) {
267 return s.kind == Kind.MTH ? s.externalType(types) : s.erasure(types);
268 }
269
270 private int makeBootstrapEntry(Dynamic dynamic) {
271 BsmKey bsmKey = dynamic.bsmKey(types);
272
273 // Figure out the index for existing BSM; create a new BSM if no key
274 Integer index = bootstrapMethods.get(bsmKey);
275 if (index == null) {
276 index = bootstrapMethods.size();
277 bootstrapMethods.put(bsmKey, index);
278 }
279
280 return index;
281 }
282
283 /**
284 * Write pool contents into given byte buffer.
285 */
286 void writePool(OutputStream out) throws IOException, PoolOverflow {
287 if (pool.overflowString != null) {
288 throw new StringOverflow(pool.overflowString);
289 }
290 int size = size();
291 if (size > MAX_ENTRIES) {
292 throw new PoolOverflow();
293 }
294 out.write(size >> 8);
295 out.write(size);
296 out.write(pool.poolbuf.elems, 0, pool.poolbuf.length);
297 }
298
299 /**
300 * Signature Generation
301 */
302 class SharedSignatureGenerator extends Types.SignatureGenerator {
303
304 /**
305 * An output buffer for type signatures.
306 */
307 ByteBuffer sigbuf = new ByteBuffer();
308
309 SharedSignatureGenerator(Types types) {
310 super(types);
311 }
312
313 /**
314 * Assemble signature of given type in string buffer.
315 * Check for uninitialized types before calling the general case.
316 */
317 @Override
318 public void assembleSig(Type type) {
319 switch (type.getTag()) {
320 case UNINITIALIZED_THIS:
321 case UNINITIALIZED_OBJECT:
322 // we don't yet have a spec for uninitialized types in the
323 // local variable table
324 assembleSig(types.erasure(((UninitializedType)type).qtype));
325 break;
326 default:
327 super.assembleSig(type);
328 }
329 }
330
331 @Override
332 protected void append(char ch) {
333 sigbuf.appendByte(ch);
334 }
335
336 @Override
337 protected void append(byte[] ba) {
338 sigbuf.appendBytes(ba);
339 }
340
341 @Override
342 protected void append(Name name) {
343 sigbuf.appendName(name);
344 }
345
346 @Override
347 protected void classReference(ClassSymbol c) {
348 enterInnerClass(c);
349 }
350
351 protected void reset() {
352 sigbuf.reset();
353 }
354
355 protected Name toName() {
356 return sigbuf.toName(names);
357 }
358 }
359
360 class WriteablePoolHelper {
361
362 /** Pool entries. */
363 private final Map<Object, Integer> keysToPos = new HashMap<>(64);
364
365 final ByteBuffer poolbuf = new ByteBuffer(POOL_BUF_SIZE);
366
367 int currentIndex = 1;
368
369 ArrayDeque<PoolConstant> todo = new ArrayDeque<>();
370
371 String overflowString = null;
372
373 private <P extends PoolConstant> int writeIfNeeded(P p) {
374 Object key = p.poolKey(types);
375 Integer index = keysToPos.get(key);
376 if (index == null) {
377 keysToPos.put(key, index = currentIndex++);
378 boolean first = todo.isEmpty();
379 todo.addLast(p);
380 if (first) {
381 while (!todo.isEmpty()) {
382 writeConstant(todo.peekFirst());
383 todo.removeFirst();
384 }
385 }
386 }
387 return index;
388 }
389
390 void writeConstant(PoolConstant c) {
391 int tag = c.poolTag();
392 switch (tag) {
393 case ClassFile.CONSTANT_Class: {
394 Type ct = c instanceof ConstantPoolQType ? ((ConstantPoolQType)c).type : (Type)c;
395 Name name = ct.hasTag(ARRAY) ?
396 typeSig(ct) :
397 c instanceof ConstantPoolQType ? names.fromString("Q" + new String(externalize(ct.tsym.flatName())) + ";") : names.fromUtf(externalize(ct.tsym.flatName()));
398 poolbuf.appendByte(tag);
399 poolbuf.appendChar(putName(name));
400 if (ct.hasTag(CLASS)) {
401 enterInnerClass((ClassSymbol)ct.tsym);
402 }
403 break;
404 }
405 case ClassFile.CONSTANT_Utf8: {
406 Name name = (Name)c;
407 poolbuf.appendByte(tag);
408 byte[] bs = name.toUtf();
409 poolbuf.appendChar(bs.length);
410 poolbuf.appendBytes(bs, 0, bs.length);
411 if (overflowString == null && bs.length > MAX_STRING_LENGTH) {
412 //report error only once
413 overflowString = new String(bs);
414 }
415 break;
416 }
417 case ClassFile.CONSTANT_InterfaceMethodref:
418 case ClassFile.CONSTANT_Methodref:
419 case ClassFile.CONSTANT_Fieldref: {
420 Symbol sym = (Symbol)c;
421 poolbuf.appendByte(tag);
422 poolbuf.appendChar(putClass((ClassSymbol)sym.owner));
423 poolbuf.appendChar(putNameAndType(sym));
424 break;
425 }
426 case ClassFile.CONSTANT_Package: {
427 PackageSymbol pkg = (PackageSymbol)c;
428 Name pkgName = names.fromUtf(externalize(pkg.flatName()));
429 poolbuf.appendByte(tag);
430 poolbuf.appendChar(putName(pkgName));
431 break;
432 }
433 case ClassFile.CONSTANT_Module: {
434 ModuleSymbol mod = (ModuleSymbol)c;
435 int modName = putName(mod.name);
436 poolbuf.appendByte(mod.poolTag());
437 poolbuf.appendChar(modName);
438 break;
439 }
440 case ClassFile.CONSTANT_Integer:
441 poolbuf.appendByte(tag);
442 poolbuf.appendInt((int)((BasicConstant)c).data);
443 break;
444 case ClassFile.CONSTANT_Float:
445 poolbuf.appendByte(tag);
446 poolbuf.appendFloat((float)((BasicConstant)c).data);
447 break;
448 case ClassFile.CONSTANT_Long:
449 currentIndex++;
450 poolbuf.appendByte(tag);
451 poolbuf.appendLong((long)((BasicConstant)c).data);
452 break;
453 case ClassFile.CONSTANT_Double:
454 currentIndex++;
455 poolbuf.appendByte(tag);
456 poolbuf.appendDouble((double)((BasicConstant)c).data);
457 break;
458 case ClassFile.CONSTANT_MethodHandle: {
459 MethodHandleSymbol h = (MethodHandleSymbol)c;
460 poolbuf.appendByte(tag);
461 poolbuf.appendByte(h.referenceKind());
462 poolbuf.appendChar(putMember(h.baseSymbol()));
463 break;
464 }
465 case ClassFile.CONSTANT_MethodType: {
466 Type.MethodType mt = (Type.MethodType)c;
467 poolbuf.appendByte(tag);
468 poolbuf.appendChar(putDescriptor(mt.baseType()));
469 break;
470 }
471 case ClassFile.CONSTANT_String: {
472 Name utf = names.fromString((String)((BasicConstant)c).data);
473 poolbuf.appendByte(tag);
474 poolbuf.appendChar(putName(utf));
475 break;
476 }
477 case ClassFile.CONSTANT_NameandType: {
478 NameAndType nt = (NameAndType)c;
479 poolbuf.appendByte(tag);
480 poolbuf.appendChar(putName(nt.name));
481 poolbuf.appendChar(putDescriptor(nt.type));
482 break;
483 }
484 case ClassFile.CONSTANT_InvokeDynamic: {
485 DynamicMethodSymbol d = (DynamicMethodSymbol)c;
486 poolbuf.appendByte(tag);
487 poolbuf.appendChar(makeBootstrapEntry(d));
488 poolbuf.appendChar(putNameAndType(d));
489 break;
490 }
491 case ClassFile.CONSTANT_Dynamic: {
492 Symbol.DynamicVarSymbol d = (Symbol.DynamicVarSymbol)c;
493 poolbuf.appendByte(tag);
494 poolbuf.appendChar(makeBootstrapEntry(d));
495 poolbuf.appendChar(putNameAndType(d));
496 break;
497 }
498 default:
499 throw new AssertionError("Unexpected constant tag: " + tag);
500 }
501 }
502
503 void reset() {
504 keysToPos.clear();
505 currentIndex = 1;
506 todo.clear();
507 overflowString = null;
508 poolbuf.reset();
509 }
510 }
511
512 int size() {
513 return pool.currentIndex;
514 }
515
516 /**
517 * Return signature of given type
518 */
519 private Name typeSig(Type type) {
520 signatureGen.reset();
521 signatureGen.assembleSig(type);
522 return signatureGen.toName();
523 }
524
525 private Name classSig(Type t) {
526 signatureGen.reset();
527 List<Type> typarams = t.getTypeArguments();
528 if (typarams.nonEmpty()) {
529 signatureGen.assembleParamsSig(typarams);
530 }
531 signatureGen.assembleSig(types.supertype(t));
532 for (Type i : types.interfaces(t))
533 signatureGen.assembleSig(i);
534 return signatureGen.toName();
535 }
536
537 void reset() {
538 innerClasses.clear();
539 preloadClasses.clear();
540 bootstrapMethods.clear();
541 pool.reset();
542 }
543 }