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