1 /*
2 * Copyright (c) 1998, 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.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "gc/shared/gcLocker.hpp"
27 #include "interpreter/bytecodes.hpp"
28 #include "interpreter/interpreter.hpp"
29 #include "interpreter/rewriter.hpp"
30 #include "memory/metaspaceShared.hpp"
31 #include "memory/resourceArea.hpp"
32 #include "oops/generateOopMap.hpp"
33 #include "prims/methodHandles.hpp"
34
35 // Computes a CPC map (new_index -> original_index) for constant pool entries
36 // that are referred to by the interpreter at runtime via the constant pool cache.
37 // Also computes a CP map (original_index -> new_index).
38 // Marks entries in CP which require additional processing.
39 void Rewriter::compute_index_maps() {
40 const int length = _pool->length();
41 init_maps(length);
42 bool saw_mh_symbol = false;
43 for (int i = 0; i < length; i++) {
44 int tag = _pool->tag_at(i).value();
45 switch (tag) {
46 case JVM_CONSTANT_InterfaceMethodref:
47 case JVM_CONSTANT_Fieldref : // fall through
48 case JVM_CONSTANT_Methodref : // fall through
49 add_cp_cache_entry(i);
50 break;
51 case JVM_CONSTANT_String:
52 case JVM_CONSTANT_MethodHandle : // fall through
53 case JVM_CONSTANT_MethodType : // fall through
54 add_resolved_references_entry(i);
55 break;
56 case JVM_CONSTANT_Utf8:
57 if (_pool->symbol_at(i) == vmSymbols::java_lang_invoke_MethodHandle() ||
58 _pool->symbol_at(i) == vmSymbols::java_lang_invoke_VarHandle()) {
59 saw_mh_symbol = true;
60 }
61 break;
62 }
63 }
64
65 // Record limits of resolved reference map for constant pool cache indices
66 record_map_limits();
67
68 guarantee((int) _cp_cache_map.length() - 1 <= (int) ((u2)-1),
69 "all cp cache indexes fit in a u2");
70
71 if (saw_mh_symbol) {
72 _method_handle_invokers.at_grow(length, 0);
73 }
74 }
75
76 // Unrewrite the bytecodes if an error occurs.
77 void Rewriter::restore_bytecodes() {
78 int len = _methods->length();
79 bool invokespecial_error = false;
80
81 for (int i = len-1; i >= 0; i--) {
82 Method* method = _methods->at(i);
83 scan_method(method, true, &invokespecial_error);
84 assert(!invokespecial_error, "reversing should not get an invokespecial error");
85 }
86 }
87
88 // Creates a constant pool cache given a CPC map
89 void Rewriter::make_constant_pool_cache(TRAPS) {
90 ClassLoaderData* loader_data = _pool->pool_holder()->class_loader_data();
91 ConstantPoolCache* cache =
92 ConstantPoolCache::allocate(loader_data, _cp_cache_map,
93 _invokedynamic_cp_cache_map,
94 _invokedynamic_references_map, CHECK);
95
96 // initialize object cache in constant pool
97 _pool->initialize_resolved_references(loader_data, _resolved_references_map,
98 _resolved_reference_limit,
99 CHECK);
100 _pool->set_cache(cache);
101 cache->set_constant_pool(_pool());
102 }
103
104
105
106 // The new finalization semantics says that registration of
107 // finalizable objects must be performed on successful return from the
108 // Object.<init> constructor. We could implement this trivially if
109 // <init> were never rewritten but since JVMTI allows this to occur, a
110 // more complicated solution is required. A special return bytecode
111 // is used only by Object.<init> to signal the finalization
112 // registration point. Additionally local 0 must be preserved so it's
113 // available to pass to the registration function. For simplicity we
114 // require that local 0 is never overwritten so it's available as an
115 // argument for registration.
116
117 void Rewriter::rewrite_Object_init(methodHandle method, TRAPS) {
118 RawBytecodeStream bcs(method);
119 while (!bcs.is_last_bytecode()) {
120 Bytecodes::Code opcode = bcs.raw_next();
121 switch (opcode) {
122 case Bytecodes::_return: *bcs.bcp() = Bytecodes::_return_register_finalizer; break;
123
124 case Bytecodes::_istore:
125 case Bytecodes::_lstore:
126 case Bytecodes::_fstore:
127 case Bytecodes::_dstore:
128 case Bytecodes::_astore:
129 if (bcs.get_index() != 0) continue;
130
131 // fall through
132 case Bytecodes::_istore_0:
133 case Bytecodes::_lstore_0:
134 case Bytecodes::_fstore_0:
135 case Bytecodes::_dstore_0:
136 case Bytecodes::_astore_0:
137 THROW_MSG(vmSymbols::java_lang_IncompatibleClassChangeError(),
138 "can't overwrite local 0 in Object.<init>");
139 break;
140 }
141 }
142 }
143
144
145 // Rewrite a classfile-order CP index into a native-order CPC index.
146 void Rewriter::rewrite_member_reference(address bcp, int offset, bool reverse) {
147 address p = bcp + offset;
148 if (!reverse) {
149 int cp_index = Bytes::get_Java_u2(p);
150 int cache_index = cp_entry_to_cp_cache(cp_index);
151 Bytes::put_native_u2(p, cache_index);
152 if (!_method_handle_invokers.is_empty())
153 maybe_rewrite_invokehandle(p - 1, cp_index, cache_index, reverse);
154 } else {
155 int cache_index = Bytes::get_native_u2(p);
156 int pool_index = cp_cache_entry_pool_index(cache_index);
157 Bytes::put_Java_u2(p, pool_index);
158 if (!_method_handle_invokers.is_empty())
159 maybe_rewrite_invokehandle(p - 1, pool_index, cache_index, reverse);
160 }
161 }
162
163 // If the constant pool entry for invokespecial is InterfaceMethodref,
164 // we need to add a separate cpCache entry for its resolution, because it is
165 // different than the resolution for invokeinterface with InterfaceMethodref.
166 // These cannot share cpCache entries. It's unclear if all invokespecial to
167 // InterfaceMethodrefs would resolve to the same thing so a new cpCache entry
168 // is created for each one. This was added with lambda.
169 void Rewriter::rewrite_invokespecial(address bcp, int offset, bool reverse, bool* invokespecial_error) {
170 address p = bcp + offset;
171 if (!reverse) {
172 int cp_index = Bytes::get_Java_u2(p);
173 if (_pool->tag_at(cp_index).is_interface_method()) {
174 int cache_index = add_invokespecial_cp_cache_entry(cp_index);
175 if (cache_index != (int)(jushort) cache_index) {
176 *invokespecial_error = true;
177 }
178 Bytes::put_native_u2(p, cache_index);
179 } else {
180 rewrite_member_reference(bcp, offset, reverse);
181 }
182 } else {
183 rewrite_member_reference(bcp, offset, reverse);
184 }
185 }
186
187
188 // Adjust the invocation bytecode for a signature-polymorphic method (MethodHandle.invoke, etc.)
189 void Rewriter::maybe_rewrite_invokehandle(address opc, int cp_index, int cache_index, bool reverse) {
190 if (!reverse) {
191 if ((*opc) == (u1)Bytecodes::_invokevirtual ||
192 // allow invokespecial as an alias, although it would be very odd:
193 (*opc) == (u1)Bytecodes::_invokespecial) {
194 assert(_pool->tag_at(cp_index).is_method(), "wrong index");
195 // Determine whether this is a signature-polymorphic method.
196 if (cp_index >= _method_handle_invokers.length()) return;
197 int status = _method_handle_invokers.at(cp_index);
198 assert(status >= -1 && status <= 1, "oob tri-state");
199 if (status == 0) {
200 if (_pool->klass_ref_at_noresolve(cp_index) == vmSymbols::java_lang_invoke_MethodHandle() &&
201 MethodHandles::is_signature_polymorphic_name(SystemDictionary::MethodHandle_klass(),
202 _pool->name_ref_at(cp_index))) {
203 // we may need a resolved_refs entry for the appendix
204 add_invokedynamic_resolved_references_entries(cp_index, cache_index);
205 status = +1;
206 } else if (_pool->klass_ref_at_noresolve(cp_index) == vmSymbols::java_lang_invoke_VarHandle() &&
207 MethodHandles::is_signature_polymorphic_name(SystemDictionary::VarHandle_klass(),
208 _pool->name_ref_at(cp_index))) {
209 // we may need a resolved_refs entry for the appendix
210 add_invokedynamic_resolved_references_entries(cp_index, cache_index);
211 status = +1;
212 } else {
213 status = -1;
214 }
215 _method_handle_invokers.at(cp_index) = status;
216 }
217 // We use a special internal bytecode for such methods (if non-static).
218 // The basic reason for this is that such methods need an extra "appendix" argument
219 // to transmit the call site's intended call type.
220 if (status > 0) {
221 (*opc) = (u1)Bytecodes::_invokehandle;
222 }
223 }
224 } else {
225 // Do not need to look at cp_index.
226 if ((*opc) == (u1)Bytecodes::_invokehandle) {
227 (*opc) = (u1)Bytecodes::_invokevirtual;
228 // Ignore corner case of original _invokespecial instruction.
229 // This is safe because (a) the signature polymorphic method was final, and
230 // (b) the implementation of MethodHandle will not call invokespecial on it.
231 }
232 }
233 }
234
235
236 void Rewriter::rewrite_invokedynamic(address bcp, int offset, bool reverse) {
237 address p = bcp + offset;
238 assert(p[-1] == Bytecodes::_invokedynamic, "not invokedynamic bytecode");
239 if (!reverse) {
240 int cp_index = Bytes::get_Java_u2(p);
241 int cache_index = add_invokedynamic_cp_cache_entry(cp_index);
242 int resolved_index = add_invokedynamic_resolved_references_entries(cp_index, cache_index);
243 // Replace the trailing four bytes with a CPC index for the dynamic
244 // call site. Unlike other CPC entries, there is one per bytecode,
245 // not just one per distinct CP entry. In other words, the
246 // CPC-to-CP relation is many-to-one for invokedynamic entries.
247 // This means we must use a larger index size than u2 to address
248 // all these entries. That is the main reason invokedynamic
249 // must have a five-byte instruction format. (Of course, other JVM
250 // implementations can use the bytes for other purposes.)
251 // Note: We use native_u4 format exclusively for 4-byte indexes.
252 Bytes::put_native_u4(p, ConstantPool::encode_invokedynamic_index(cache_index));
253 // add the bcp in case we need to patch this bytecode if we also find a
254 // invokespecial/InterfaceMethodref in the bytecode stream
255 _patch_invokedynamic_bcps->push(p);
256 _patch_invokedynamic_refs->push(resolved_index);
257 } else {
258 int cache_index = ConstantPool::decode_invokedynamic_index(
259 Bytes::get_native_u4(p));
260 // We will reverse the bytecode rewriting _after_ adjusting them.
261 // Adjust the cache index by offset to the invokedynamic entries in the
262 // cpCache plus the delta if the invokedynamic bytecodes were adjusted.
263 int adjustment = cp_cache_delta() + _first_iteration_cp_cache_limit;
264 int cp_index = invokedynamic_cp_cache_entry_pool_index(cache_index - adjustment);
265 assert(_pool->tag_at(cp_index).is_invoke_dynamic(), "wrong index");
266 // zero out 4 bytes
267 Bytes::put_Java_u4(p, 0);
268 Bytes::put_Java_u2(p, cp_index);
269 }
270 }
271
272 void Rewriter::patch_invokedynamic_bytecodes() {
273 // If the end of the cp_cache is the same as after initializing with the
274 // cpool, nothing needs to be done. Invokedynamic bytecodes are at the
275 // correct offsets. ie. no invokespecials added
276 int delta = cp_cache_delta();
277 if (delta > 0) {
278 int length = _patch_invokedynamic_bcps->length();
279 assert(length == _patch_invokedynamic_refs->length(),
280 "lengths should match");
281 for (int i = 0; i < length; i++) {
282 address p = _patch_invokedynamic_bcps->at(i);
283 int cache_index = ConstantPool::decode_invokedynamic_index(
284 Bytes::get_native_u4(p));
285 Bytes::put_native_u4(p, ConstantPool::encode_invokedynamic_index(cache_index + delta));
286
287 // invokedynamic resolved references map also points to cp cache and must
288 // add delta to each.
289 int resolved_index = _patch_invokedynamic_refs->at(i);
290 for (int entry = 0; entry < ConstantPoolCacheEntry::_indy_resolved_references_entries; entry++) {
291 assert(_invokedynamic_references_map.at(resolved_index + entry) == cache_index,
292 "should be the same index");
293 _invokedynamic_references_map.at_put(resolved_index+entry,
294 cache_index + delta);
295 }
296 }
297 }
298 }
299
300
301 // Rewrite some ldc bytecodes to _fast_aldc
302 void Rewriter::maybe_rewrite_ldc(address bcp, int offset, bool is_wide,
303 bool reverse) {
304 if (!reverse) {
305 assert((*bcp) == (is_wide ? Bytecodes::_ldc_w : Bytecodes::_ldc), "not ldc bytecode");
306 address p = bcp + offset;
307 int cp_index = is_wide ? Bytes::get_Java_u2(p) : (u1)(*p);
308 constantTag tag = _pool->tag_at(cp_index).value();
309 if (tag.is_method_handle() || tag.is_method_type() || tag.is_string()) {
310 int ref_index = cp_entry_to_resolved_references(cp_index);
311 if (is_wide) {
312 (*bcp) = Bytecodes::_fast_aldc_w;
313 assert(ref_index == (u2)ref_index, "index overflow");
314 Bytes::put_native_u2(p, ref_index);
315 } else {
316 (*bcp) = Bytecodes::_fast_aldc;
317 assert(ref_index == (u1)ref_index, "index overflow");
318 (*p) = (u1)ref_index;
319 }
320 }
321 } else {
322 Bytecodes::Code rewritten_bc =
323 (is_wide ? Bytecodes::_fast_aldc_w : Bytecodes::_fast_aldc);
324 if ((*bcp) == rewritten_bc) {
325 address p = bcp + offset;
326 int ref_index = is_wide ? Bytes::get_native_u2(p) : (u1)(*p);
327 int pool_index = resolved_references_entry_to_pool_index(ref_index);
328 if (is_wide) {
329 (*bcp) = Bytecodes::_ldc_w;
330 assert(pool_index == (u2)pool_index, "index overflow");
331 Bytes::put_Java_u2(p, pool_index);
332 } else {
333 (*bcp) = Bytecodes::_ldc;
334 assert(pool_index == (u1)pool_index, "index overflow");
335 (*p) = (u1)pool_index;
336 }
337 }
338 }
339 }
340
341
342 // Rewrites a method given the index_map information
343 void Rewriter::scan_method(Method* method, bool reverse, bool* invokespecial_error) {
344
345 int nof_jsrs = 0;
346 bool has_monitor_bytecodes = false;
347
348 {
349 // We cannot tolerate a GC in this block, because we've
350 // cached the bytecodes in 'code_base'. If the Method*
351 // moves, the bytecodes will also move.
352 NoSafepointVerifier nsv;
353 Bytecodes::Code c;
354
355 // Bytecodes and their length
356 const address code_base = method->code_base();
357 const int code_length = method->code_size();
358
359 int bc_length;
360 for (int bci = 0; bci < code_length; bci += bc_length) {
361 address bcp = code_base + bci;
362 int prefix_length = 0;
363 c = (Bytecodes::Code)(*bcp);
364
365 // Since we have the code, see if we can get the length
366 // directly. Some more complicated bytecodes will report
367 // a length of zero, meaning we need to make another method
368 // call to calculate the length.
369 bc_length = Bytecodes::length_for(c);
370 if (bc_length == 0) {
371 bc_length = Bytecodes::length_at(method, bcp);
372
373 // length_at will put us at the bytecode after the one modified
374 // by 'wide'. We don't currently examine any of the bytecodes
375 // modified by wide, but in case we do in the future...
376 if (c == Bytecodes::_wide) {
377 prefix_length = 1;
378 c = (Bytecodes::Code)bcp[1];
379 }
380 }
381
382 assert(bc_length != 0, "impossible bytecode length");
383
384 switch (c) {
385 case Bytecodes::_lookupswitch : {
386 #ifndef CC_INTERP
387 Bytecode_lookupswitch bc(method, bcp);
388 (*bcp) = (
389 bc.number_of_pairs() < BinarySwitchThreshold
390 ? Bytecodes::_fast_linearswitch
391 : Bytecodes::_fast_binaryswitch
392 );
393 #endif
394 break;
395 }
396 case Bytecodes::_fast_linearswitch:
397 case Bytecodes::_fast_binaryswitch: {
398 #ifndef CC_INTERP
399 (*bcp) = Bytecodes::_lookupswitch;
400 #endif
401 break;
402 }
403
404 case Bytecodes::_invokespecial : {
405 rewrite_invokespecial(bcp, prefix_length+1, reverse, invokespecial_error);
406 break;
407 }
408
409 case Bytecodes::_getstatic : // fall through
410 case Bytecodes::_putstatic : // fall through
411 case Bytecodes::_getfield : // fall through
412 case Bytecodes::_putfield : // fall through
413 case Bytecodes::_invokevirtual : // fall through
414 case Bytecodes::_invokestatic :
415 case Bytecodes::_invokeinterface:
416 case Bytecodes::_invokehandle : // if reverse=true
417 rewrite_member_reference(bcp, prefix_length+1, reverse);
418 break;
419 case Bytecodes::_invokedynamic:
420 rewrite_invokedynamic(bcp, prefix_length+1, reverse);
421 break;
422 case Bytecodes::_ldc:
423 case Bytecodes::_fast_aldc: // if reverse=true
424 maybe_rewrite_ldc(bcp, prefix_length+1, false, reverse);
425 break;
426 case Bytecodes::_ldc_w:
427 case Bytecodes::_fast_aldc_w: // if reverse=true
428 maybe_rewrite_ldc(bcp, prefix_length+1, true, reverse);
429 break;
430 case Bytecodes::_jsr : // fall through
431 case Bytecodes::_jsr_w : nof_jsrs++; break;
432 case Bytecodes::_monitorenter : // fall through
433 case Bytecodes::_monitorexit : has_monitor_bytecodes = true; break;
434 }
435 }
436 }
437
438 // Update access flags
439 if (has_monitor_bytecodes) {
440 method->set_has_monitor_bytecodes();
441 }
442
443 // The present of a jsr bytecode implies that the method might potentially
444 // have to be rewritten, so we run the oopMapGenerator on the method
445 if (nof_jsrs > 0) {
446 method->set_has_jsrs();
447 // Second pass will revisit this method.
448 assert(method->has_jsrs(), "didn't we just set this?");
449 }
450 }
451
452 // After constant pool is created, revisit methods containing jsrs.
453 methodHandle Rewriter::rewrite_jsrs(methodHandle method, TRAPS) {
454 ResourceMark rm(THREAD);
455 ResolveOopMapConflicts romc(method);
456 methodHandle original_method = method;
457 method = romc.do_potential_rewrite(CHECK_(methodHandle()));
458 // Update monitor matching info.
459 if (romc.monitor_safe()) {
460 method->set_guaranteed_monitor_matching();
461 }
462
463 return method;
464 }
465
466 void Rewriter::rewrite_bytecodes(TRAPS) {
467 assert(_pool->cache() == NULL, "constant pool cache must not be set yet");
468
469 // determine index maps for Method* rewriting
470 compute_index_maps();
471
472 if (RegisterFinalizersAtInit && _klass->name() == vmSymbols::java_lang_Object()) {
473 bool did_rewrite = false;
474 int i = _methods->length();
475 while (i-- > 0) {
476 Method* method = _methods->at(i);
477 if (method->intrinsic_id() == vmIntrinsics::_Object_init) {
478 // rewrite the return bytecodes of Object.<init> to register the
479 // object for finalization if needed.
480 methodHandle m(THREAD, method);
481 rewrite_Object_init(m, CHECK);
482 did_rewrite = true;
483 break;
484 }
485 }
486 assert(did_rewrite, "must find Object::<init> to rewrite it");
487 }
488
489 // rewrite methods, in two passes
490 int len = _methods->length();
491 bool invokespecial_error = false;
492
493 for (int i = len-1; i >= 0; i--) {
494 Method* method = _methods->at(i);
495 scan_method(method, false, &invokespecial_error);
496 if (invokespecial_error) {
497 // If you get an error here, there is no reversing bytecodes
498 // This exception is stored for this class and no further attempt is
499 // made at verifying or rewriting.
500 THROW_MSG(vmSymbols::java_lang_InternalError(),
501 "This classfile overflows invokespecial for interfaces "
502 "and cannot be loaded");
503 return;
504 }
505 }
506
507 // May have to fix invokedynamic bytecodes if invokestatic/InterfaceMethodref
508 // entries had to be added.
509 patch_invokedynamic_bytecodes();
510 }
511
512 void Rewriter::rewrite(instanceKlassHandle klass, TRAPS) {
513 if (!DumpSharedSpaces) {
514 assert(!MetaspaceShared::is_in_shared_space(klass()), "archive methods must not be rewritten at run time");
515 }
516 ResourceMark rm(THREAD);
517 Rewriter rw(klass, klass->constants(), klass->methods(), CHECK);
518 // (That's all, folks.)
519 }
520
521 Rewriter::Rewriter(instanceKlassHandle klass, const constantPoolHandle& cpool, Array<Method*>* methods, TRAPS)
522 : _klass(klass),
523 _pool(cpool),
524 _methods(methods),
525 _cp_map(cpool->length()),
526 _cp_cache_map(cpool->length() / 2),
527 _reference_map(cpool->length()),
528 _resolved_references_map(cpool->length() / 2),
529 _invokedynamic_references_map(cpool->length() / 2),
530 _method_handle_invokers(cpool->length()),
531 _invokedynamic_cp_cache_map(cpool->length() / 4)
532 {
533
534 // Rewrite bytecodes - exception here exits.
535 rewrite_bytecodes(CHECK);
536
537 // Stress restoring bytecodes
538 if (StressRewriter) {
539 restore_bytecodes();
540 rewrite_bytecodes(CHECK);
541 }
542
543 // allocate constant pool cache, now that we've seen all the bytecodes
544 make_constant_pool_cache(THREAD);
545
546 // Restore bytecodes to their unrewritten state if there are exceptions
547 // rewriting bytecodes or allocating the cpCache
548 if (HAS_PENDING_EXCEPTION) {
549 restore_bytecodes();
550 return;
551 }
552
553 // Relocate after everything, but still do this under the is_rewritten flag,
554 // so methods with jsrs in custom class lists in aren't attempted to be
555 // rewritten in the RO section of the shared archive.
556 // Relocated bytecodes don't have to be restored, only the cp cache entries
557 int len = _methods->length();
558 for (int i = len-1; i >= 0; i--) {
559 methodHandle m(THREAD, _methods->at(i));
560
561 if (m->has_jsrs()) {
562 m = rewrite_jsrs(m, THREAD);
563 // Restore bytecodes to their unrewritten state if there are exceptions
564 // relocating bytecodes. If some are relocated, that is ok because that
565 // doesn't affect constant pool to cpCache rewriting.
566 if (HAS_PENDING_EXCEPTION) {
567 restore_bytecodes();
568 return;
569 }
570 // Method might have gotten rewritten.
571 methods->at_put(i, m());
572 }
573 }
574 }