1 /*
2 * Copyright (c) 1998, 2017, 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->set_cache(cache);
98 cache->set_constant_pool(_pool());
99
100 // _resolved_references is stored in pool->cache(), so need to be done after
101 // the above lines.
102 _pool->initialize_resolved_references(loader_data, _resolved_references_map,
103 _resolved_reference_limit,
104 CHECK);
105 }
106
107
108
109 // The new finalization semantics says that registration of
110 // finalizable objects must be performed on successful return from the
111 // Object.<init> constructor. We could implement this trivially if
112 // <init> were never rewritten but since JVMTI allows this to occur, a
113 // more complicated solution is required. A special return bytecode
114 // is used only by Object.<init> to signal the finalization
115 // registration point. Additionally local 0 must be preserved so it's
116 // available to pass to the registration function. For simplicity we
117 // require that local 0 is never overwritten so it's available as an
118 // argument for registration.
119
120 void Rewriter::rewrite_Object_init(methodHandle method, TRAPS) {
121 RawBytecodeStream bcs(method);
122 while (!bcs.is_last_bytecode()) {
123 Bytecodes::Code opcode = bcs.raw_next();
124 switch (opcode) {
125 case Bytecodes::_return: *bcs.bcp() = Bytecodes::_return_register_finalizer; break;
126
127 case Bytecodes::_istore:
128 case Bytecodes::_lstore:
129 case Bytecodes::_fstore:
130 case Bytecodes::_dstore:
131 case Bytecodes::_astore:
132 if (bcs.get_index() != 0) continue;
133
134 // fall through
135 case Bytecodes::_istore_0:
136 case Bytecodes::_lstore_0:
137 case Bytecodes::_fstore_0:
138 case Bytecodes::_dstore_0:
139 case Bytecodes::_astore_0:
140 THROW_MSG(vmSymbols::java_lang_IncompatibleClassChangeError(),
141 "can't overwrite local 0 in Object.<init>");
142 break;
143
144 default:
145 break;
146 }
147 }
148 }
149
150
151 // Rewrite a classfile-order CP index into a native-order CPC index.
152 void Rewriter::rewrite_member_reference(address bcp, int offset, bool reverse) {
153 address p = bcp + offset;
154 if (!reverse) {
155 int cp_index = Bytes::get_Java_u2(p);
156 int cache_index = cp_entry_to_cp_cache(cp_index);
157 Bytes::put_native_u2(p, cache_index);
158 if (!_method_handle_invokers.is_empty())
159 maybe_rewrite_invokehandle(p - 1, cp_index, cache_index, reverse);
160 } else {
161 int cache_index = Bytes::get_native_u2(p);
162 int pool_index = cp_cache_entry_pool_index(cache_index);
163 Bytes::put_Java_u2(p, pool_index);
164 if (!_method_handle_invokers.is_empty())
165 maybe_rewrite_invokehandle(p - 1, pool_index, cache_index, reverse);
166 }
167 }
168
169 // If the constant pool entry for invokespecial is InterfaceMethodref,
170 // we need to add a separate cpCache entry for its resolution, because it is
171 // different than the resolution for invokeinterface with InterfaceMethodref.
172 // These cannot share cpCache entries.
173 void Rewriter::rewrite_invokespecial(address bcp, int offset, bool reverse, bool* invokespecial_error) {
174 address p = bcp + offset;
175 if (!reverse) {
176 int cp_index = Bytes::get_Java_u2(p);
177 if (_pool->tag_at(cp_index).is_interface_method()) {
178 int cache_index = add_invokespecial_cp_cache_entry(cp_index);
179 if (cache_index != (int)(jushort) cache_index) {
180 *invokespecial_error = true;
181 }
182 Bytes::put_native_u2(p, cache_index);
183 } else {
184 rewrite_member_reference(bcp, offset, reverse);
185 }
186 } else {
187 rewrite_member_reference(bcp, offset, reverse);
188 }
189 }
190
191
192 // Adjust the invocation bytecode for a signature-polymorphic method (MethodHandle.invoke, etc.)
193 void Rewriter::maybe_rewrite_invokehandle(address opc, int cp_index, int cache_index, bool reverse) {
194 if (!reverse) {
195 if ((*opc) == (u1)Bytecodes::_invokevirtual ||
196 // allow invokespecial as an alias, although it would be very odd:
197 (*opc) == (u1)Bytecodes::_invokespecial) {
198 assert(_pool->tag_at(cp_index).is_method(), "wrong index");
199 // Determine whether this is a signature-polymorphic method.
200 if (cp_index >= _method_handle_invokers.length()) return;
201 int status = _method_handle_invokers.at(cp_index);
202 assert(status >= -1 && status <= 1, "oob tri-state");
203 if (status == 0) {
204 if (_pool->klass_ref_at_noresolve(cp_index) == vmSymbols::java_lang_invoke_MethodHandle() &&
205 MethodHandles::is_signature_polymorphic_name(SystemDictionary::MethodHandle_klass(),
206 _pool->name_ref_at(cp_index))) {
207 // we may need a resolved_refs entry for the appendix
208 add_invokedynamic_resolved_references_entries(cp_index, cache_index);
209 status = +1;
210 } else if (_pool->klass_ref_at_noresolve(cp_index) == vmSymbols::java_lang_invoke_VarHandle() &&
211 MethodHandles::is_signature_polymorphic_name(SystemDictionary::VarHandle_klass(),
212 _pool->name_ref_at(cp_index))) {
213 // we may need a resolved_refs entry for the appendix
214 add_invokedynamic_resolved_references_entries(cp_index, cache_index);
215 status = +1;
216 } else {
217 status = -1;
218 }
219 _method_handle_invokers.at(cp_index) = status;
220 }
221 // We use a special internal bytecode for such methods (if non-static).
222 // The basic reason for this is that such methods need an extra "appendix" argument
223 // to transmit the call site's intended call type.
224 if (status > 0) {
225 (*opc) = (u1)Bytecodes::_invokehandle;
226 }
227 }
228 } else {
229 // Do not need to look at cp_index.
230 if ((*opc) == (u1)Bytecodes::_invokehandle) {
231 (*opc) = (u1)Bytecodes::_invokevirtual;
232 // Ignore corner case of original _invokespecial instruction.
233 // This is safe because (a) the signature polymorphic method was final, and
234 // (b) the implementation of MethodHandle will not call invokespecial on it.
235 }
236 }
237 }
238
239
240 void Rewriter::rewrite_invokedynamic(address bcp, int offset, bool reverse) {
241 address p = bcp + offset;
242 assert(p[-1] == Bytecodes::_invokedynamic, "not invokedynamic bytecode");
243 if (!reverse) {
244 int cp_index = Bytes::get_Java_u2(p);
245 int cache_index = add_invokedynamic_cp_cache_entry(cp_index);
246 int resolved_index = add_invokedynamic_resolved_references_entries(cp_index, cache_index);
247 // Replace the trailing four bytes with a CPC index for the dynamic
248 // call site. Unlike other CPC entries, there is one per bytecode,
249 // not just one per distinct CP entry. In other words, the
250 // CPC-to-CP relation is many-to-one for invokedynamic entries.
251 // This means we must use a larger index size than u2 to address
252 // all these entries. That is the main reason invokedynamic
253 // must have a five-byte instruction format. (Of course, other JVM
254 // implementations can use the bytes for other purposes.)
255 // Note: We use native_u4 format exclusively for 4-byte indexes.
256 Bytes::put_native_u4(p, ConstantPool::encode_invokedynamic_index(cache_index));
257 // add the bcp in case we need to patch this bytecode if we also find a
258 // invokespecial/InterfaceMethodref in the bytecode stream
259 _patch_invokedynamic_bcps->push(p);
260 _patch_invokedynamic_refs->push(resolved_index);
261 } else {
262 int cache_index = ConstantPool::decode_invokedynamic_index(
263 Bytes::get_native_u4(p));
264 // We will reverse the bytecode rewriting _after_ adjusting them.
265 // Adjust the cache index by offset to the invokedynamic entries in the
266 // cpCache plus the delta if the invokedynamic bytecodes were adjusted.
267 int adjustment = cp_cache_delta() + _first_iteration_cp_cache_limit;
268 int cp_index = invokedynamic_cp_cache_entry_pool_index(cache_index - adjustment);
269 assert(_pool->tag_at(cp_index).is_invoke_dynamic(), "wrong index");
270 // zero out 4 bytes
271 Bytes::put_Java_u4(p, 0);
272 Bytes::put_Java_u2(p, cp_index);
273 }
274 }
275
276 void Rewriter::patch_invokedynamic_bytecodes() {
277 // If the end of the cp_cache is the same as after initializing with the
278 // cpool, nothing needs to be done. Invokedynamic bytecodes are at the
279 // correct offsets. ie. no invokespecials added
280 int delta = cp_cache_delta();
281 if (delta > 0) {
282 int length = _patch_invokedynamic_bcps->length();
283 assert(length == _patch_invokedynamic_refs->length(),
284 "lengths should match");
285 for (int i = 0; i < length; i++) {
286 address p = _patch_invokedynamic_bcps->at(i);
287 int cache_index = ConstantPool::decode_invokedynamic_index(
288 Bytes::get_native_u4(p));
289 Bytes::put_native_u4(p, ConstantPool::encode_invokedynamic_index(cache_index + delta));
290
291 // invokedynamic resolved references map also points to cp cache and must
292 // add delta to each.
293 int resolved_index = _patch_invokedynamic_refs->at(i);
294 for (int entry = 0; entry < ConstantPoolCacheEntry::_indy_resolved_references_entries; entry++) {
295 assert(_invokedynamic_references_map.at(resolved_index + entry) == cache_index,
296 "should be the same index");
297 _invokedynamic_references_map.at_put(resolved_index+entry,
298 cache_index + delta);
299 }
300 }
301 }
302 }
303
304
305 // Rewrite some ldc bytecodes to _fast_aldc
306 void Rewriter::maybe_rewrite_ldc(address bcp, int offset, bool is_wide,
307 bool reverse) {
308 if (!reverse) {
309 assert((*bcp) == (is_wide ? Bytecodes::_ldc_w : Bytecodes::_ldc), "not ldc bytecode");
310 address p = bcp + offset;
311 int cp_index = is_wide ? Bytes::get_Java_u2(p) : (u1)(*p);
312 constantTag tag = _pool->tag_at(cp_index).value();
313 if (tag.is_method_handle() || tag.is_method_type() || tag.is_string()) {
314 int ref_index = cp_entry_to_resolved_references(cp_index);
315 if (is_wide) {
316 (*bcp) = Bytecodes::_fast_aldc_w;
317 assert(ref_index == (u2)ref_index, "index overflow");
318 Bytes::put_native_u2(p, ref_index);
319 } else {
320 (*bcp) = Bytecodes::_fast_aldc;
321 assert(ref_index == (u1)ref_index, "index overflow");
322 (*p) = (u1)ref_index;
323 }
324 }
325 } else {
326 Bytecodes::Code rewritten_bc =
327 (is_wide ? Bytecodes::_fast_aldc_w : Bytecodes::_fast_aldc);
328 if ((*bcp) == rewritten_bc) {
329 address p = bcp + offset;
330 int ref_index = is_wide ? Bytes::get_native_u2(p) : (u1)(*p);
331 int pool_index = resolved_references_entry_to_pool_index(ref_index);
332 if (is_wide) {
333 (*bcp) = Bytecodes::_ldc_w;
334 assert(pool_index == (u2)pool_index, "index overflow");
335 Bytes::put_Java_u2(p, pool_index);
336 } else {
337 (*bcp) = Bytecodes::_ldc;
338 assert(pool_index == (u1)pool_index, "index overflow");
339 (*p) = (u1)pool_index;
340 }
341 }
342 }
343 }
344
345
346 // Rewrites a method given the index_map information
347 void Rewriter::scan_method(Method* method, bool reverse, bool* invokespecial_error) {
348
349 int nof_jsrs = 0;
350 bool has_monitor_bytecodes = false;
351
352 {
353 // We cannot tolerate a GC in this block, because we've
354 // cached the bytecodes in 'code_base'. If the Method*
355 // moves, the bytecodes will also move.
356 NoSafepointVerifier nsv;
357 Bytecodes::Code c;
358
359 // Bytecodes and their length
360 const address code_base = method->code_base();
361 const int code_length = method->code_size();
362
363 int bc_length;
364 for (int bci = 0; bci < code_length; bci += bc_length) {
365 address bcp = code_base + bci;
366 int prefix_length = 0;
367 c = (Bytecodes::Code)(*bcp);
368
369 // Since we have the code, see if we can get the length
370 // directly. Some more complicated bytecodes will report
371 // a length of zero, meaning we need to make another method
372 // call to calculate the length.
373 bc_length = Bytecodes::length_for(c);
374 if (bc_length == 0) {
375 bc_length = Bytecodes::length_at(method, bcp);
376
377 // length_at will put us at the bytecode after the one modified
378 // by 'wide'. We don't currently examine any of the bytecodes
379 // modified by wide, but in case we do in the future...
380 if (c == Bytecodes::_wide) {
381 prefix_length = 1;
382 c = (Bytecodes::Code)bcp[1];
383 }
384 }
385
386 assert(bc_length != 0, "impossible bytecode length");
387
388 switch (c) {
389 case Bytecodes::_lookupswitch : {
390 #ifndef CC_INTERP
391 Bytecode_lookupswitch bc(method, bcp);
392 (*bcp) = (
393 bc.number_of_pairs() < BinarySwitchThreshold
394 ? Bytecodes::_fast_linearswitch
395 : Bytecodes::_fast_binaryswitch
396 );
397 #endif
398 break;
399 }
400 case Bytecodes::_fast_linearswitch:
401 case Bytecodes::_fast_binaryswitch: {
402 #ifndef CC_INTERP
403 (*bcp) = Bytecodes::_lookupswitch;
404 #endif
405 break;
406 }
407
408 case Bytecodes::_invokespecial : {
409 rewrite_invokespecial(bcp, prefix_length+1, reverse, invokespecial_error);
410 break;
411 }
412
413 case Bytecodes::_putstatic :
414 case Bytecodes::_putfield : {
415 if (!reverse) {
416 // Check if any final field of the class given as parameter is modified
417 // outside of initializer methods of the class. Fields that are modified
418 // are marked with a flag. For marked fields, the compilers do not perform
419 // constant folding (as the field can be changed after initialization).
420 //
421 // The check is performed after verification and only if verification has
422 // succeeded. Therefore, the class is guaranteed to be well-formed.
423 InstanceKlass* klass = method->method_holder();
424 u2 bc_index = Bytes::get_Java_u2(bcp + prefix_length + 1);
425 constantPoolHandle cp(method->constants());
426 Symbol* ref_class_name = cp->klass_name_at(cp->klass_ref_index_at(bc_index));
427
428 if (klass->name() == ref_class_name) {
429 Symbol* field_name = cp->name_ref_at(bc_index);
430 Symbol* field_sig = cp->signature_ref_at(bc_index);
431
432 fieldDescriptor fd;
433 if (klass->find_field(field_name, field_sig, &fd) != NULL) {
434 if (fd.access_flags().is_final()) {
435 if (fd.access_flags().is_static()) {
436 if (!method->is_static_initializer()) {
437 fd.set_has_initialized_final_update(true);
438 }
439 } else {
440 if (!method->is_object_initializer()) {
441 fd.set_has_initialized_final_update(true);
442 }
443 }
444 }
445 }
446 }
447 }
448 }
449 // fall through
450 case Bytecodes::_getstatic : // fall through
451 case Bytecodes::_getfield : // fall through
452 case Bytecodes::_invokevirtual : // fall through
453 case Bytecodes::_invokestatic :
454 case Bytecodes::_invokeinterface:
455 case Bytecodes::_invokehandle : // if reverse=true
456 rewrite_member_reference(bcp, prefix_length+1, reverse);
457 break;
458 case Bytecodes::_invokedynamic:
459 rewrite_invokedynamic(bcp, prefix_length+1, reverse);
460 break;
461 case Bytecodes::_ldc:
462 case Bytecodes::_fast_aldc: // if reverse=true
463 maybe_rewrite_ldc(bcp, prefix_length+1, false, reverse);
464 break;
465 case Bytecodes::_ldc_w:
466 case Bytecodes::_fast_aldc_w: // if reverse=true
467 maybe_rewrite_ldc(bcp, prefix_length+1, true, reverse);
468 break;
469 case Bytecodes::_jsr : // fall through
470 case Bytecodes::_jsr_w : nof_jsrs++; break;
471 case Bytecodes::_monitorenter : // fall through
472 case Bytecodes::_monitorexit : has_monitor_bytecodes = true; break;
473
474 default: break;
475 }
476 }
477 }
478
479 // Update access flags
480 if (has_monitor_bytecodes) {
481 method->set_has_monitor_bytecodes();
482 }
483
484 // The present of a jsr bytecode implies that the method might potentially
485 // have to be rewritten, so we run the oopMapGenerator on the method
486 if (nof_jsrs > 0) {
487 method->set_has_jsrs();
488 // Second pass will revisit this method.
489 assert(method->has_jsrs(), "didn't we just set this?");
490 }
491 }
492
493 // After constant pool is created, revisit methods containing jsrs.
494 methodHandle Rewriter::rewrite_jsrs(methodHandle method, TRAPS) {
495 ResourceMark rm(THREAD);
496 ResolveOopMapConflicts romc(method);
497 methodHandle original_method = method;
498 method = romc.do_potential_rewrite(CHECK_(methodHandle()));
499 // Update monitor matching info.
500 if (romc.monitor_safe()) {
501 method->set_guaranteed_monitor_matching();
502 }
503
504 return method;
505 }
506
507 void Rewriter::rewrite_bytecodes(TRAPS) {
508 assert(_pool->cache() == NULL, "constant pool cache must not be set yet");
509
510 // determine index maps for Method* rewriting
511 compute_index_maps();
512
513 if (RegisterFinalizersAtInit && _klass->name() == vmSymbols::java_lang_Object()) {
514 bool did_rewrite = false;
515 int i = _methods->length();
516 while (i-- > 0) {
517 Method* method = _methods->at(i);
518 if (method->intrinsic_id() == vmIntrinsics::_Object_init) {
519 // rewrite the return bytecodes of Object.<init> to register the
520 // object for finalization if needed.
521 methodHandle m(THREAD, method);
522 rewrite_Object_init(m, CHECK);
523 did_rewrite = true;
524 break;
525 }
526 }
527 assert(did_rewrite, "must find Object::<init> to rewrite it");
528 }
529
530 // rewrite methods, in two passes
531 int len = _methods->length();
532 bool invokespecial_error = false;
533
534 for (int i = len-1; i >= 0; i--) {
535 Method* method = _methods->at(i);
536 scan_method(method, false, &invokespecial_error);
537 if (invokespecial_error) {
538 // If you get an error here, there is no reversing bytecodes
539 // This exception is stored for this class and no further attempt is
540 // made at verifying or rewriting.
541 THROW_MSG(vmSymbols::java_lang_InternalError(),
542 "This classfile overflows invokespecial for interfaces "
543 "and cannot be loaded");
544 return;
545 }
546 }
547
548 // May have to fix invokedynamic bytecodes if invokestatic/InterfaceMethodref
549 // entries had to be added.
550 patch_invokedynamic_bytecodes();
551 }
552
553 void Rewriter::rewrite(InstanceKlass* klass, TRAPS) {
554 if (!DumpSharedSpaces) {
555 assert(!MetaspaceShared::is_in_shared_space(klass), "archive methods must not be rewritten at run time");
556 }
557 ResourceMark rm(THREAD);
558 Rewriter rw(klass, klass->constants(), klass->methods(), CHECK);
559 // (That's all, folks.)
560 }
561
562 Rewriter::Rewriter(InstanceKlass* klass, const constantPoolHandle& cpool, Array<Method*>* methods, TRAPS)
563 : _klass(klass),
564 _pool(cpool),
565 _methods(methods),
566 _cp_map(cpool->length()),
567 _cp_cache_map(cpool->length() / 2),
568 _reference_map(cpool->length()),
569 _resolved_references_map(cpool->length() / 2),
570 _invokedynamic_references_map(cpool->length() / 2),
571 _method_handle_invokers(cpool->length()),
572 _invokedynamic_cp_cache_map(cpool->length() / 4)
573 {
574
575 // Rewrite bytecodes - exception here exits.
576 rewrite_bytecodes(CHECK);
577
578 // Stress restoring bytecodes
579 if (StressRewriter) {
580 restore_bytecodes();
581 rewrite_bytecodes(CHECK);
582 }
583
584 // allocate constant pool cache, now that we've seen all the bytecodes
585 make_constant_pool_cache(THREAD);
586
587 // Restore bytecodes to their unrewritten state if there are exceptions
588 // rewriting bytecodes or allocating the cpCache
589 if (HAS_PENDING_EXCEPTION) {
590 restore_bytecodes();
591 return;
592 }
593
594 // Relocate after everything, but still do this under the is_rewritten flag,
595 // so methods with jsrs in custom class lists in aren't attempted to be
596 // rewritten in the RO section of the shared archive.
597 // Relocated bytecodes don't have to be restored, only the cp cache entries
598 int len = _methods->length();
599 for (int i = len-1; i >= 0; i--) {
600 methodHandle m(THREAD, _methods->at(i));
601
602 if (m->has_jsrs()) {
603 m = rewrite_jsrs(m, THREAD);
604 // Restore bytecodes to their unrewritten state if there are exceptions
605 // relocating bytecodes. If some are relocated, that is ok because that
606 // doesn't affect constant pool to cpCache rewriting.
607 if (HAS_PENDING_EXCEPTION) {
608 restore_bytecodes();
609 return;
610 }
611 // Method might have gotten rewritten.
612 methods->at_put(i, m());
613 }
614 }
615 }