1 /*
2 * Copyright (c) 1998, 2015, 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 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 int cp_index = Bytes::get_Java_u2(p);
147 int cache_index = cp_entry_to_cp_cache(cp_index);
148 Bytes::put_native_u2(p, cache_index);
149 if (!_method_handle_invokers.is_empty())
150 maybe_rewrite_invokehandle(p - 1, cp_index, cache_index, reverse);
151 } else {
152 int cache_index = Bytes::get_native_u2(p);
153 int pool_index = cp_cache_entry_pool_index(cache_index);
154 Bytes::put_Java_u2(p, pool_index);
155 if (!_method_handle_invokers.is_empty())
156 maybe_rewrite_invokehandle(p - 1, pool_index, cache_index, reverse);
157 }
158 }
159
160 // If the constant pool entry for invokespecial is InterfaceMethodref,
161 // we need to add a separate cpCache entry for its resolution, because it is
162 // different than the resolution for invokeinterface with InterfaceMethodref.
163 // These cannot share cpCache entries. It's unclear if all invokespecial to
164 // InterfaceMethodrefs would resolve to the same thing so a new cpCache entry
165 // is created for each one. This was added with lambda.
166 void Rewriter::rewrite_invokespecial(address bcp, int offset, bool reverse, bool* invokespecial_error) {
167 address p = bcp + offset;
168 if (!reverse) {
169 int cp_index = Bytes::get_Java_u2(p);
170 if (_pool->tag_at(cp_index).is_interface_method()) {
171 int cache_index = add_invokespecial_cp_cache_entry(cp_index);
172 if (cache_index != (int)(jushort) cache_index) {
173 *invokespecial_error = true;
174 }
175 Bytes::put_native_u2(p, cache_index);
176 } else {
177 rewrite_member_reference(bcp, offset, reverse);
178 }
179 } else {
180 rewrite_member_reference(bcp, offset, reverse);
181 }
182 }
183
184
185 // Adjust the invocation bytecode for a signature-polymorphic method (MethodHandle.invoke, etc.)
186 void Rewriter::maybe_rewrite_invokehandle(address opc, int cp_index, int cache_index, bool reverse) {
187 if (!reverse) {
188 if ((*opc) == (u1)Bytecodes::_invokevirtual ||
189 // allow invokespecial as an alias, although it would be very odd:
190 (*opc) == (u1)Bytecodes::_invokespecial) {
191 assert(_pool->tag_at(cp_index).is_method(), "wrong index");
192 // Determine whether this is a signature-polymorphic method.
193 if (cp_index >= _method_handle_invokers.length()) return;
194 int status = _method_handle_invokers[cp_index];
195 assert(status >= -1 && status <= 1, "oob tri-state");
196 if (status == 0) {
197 if (_pool->klass_ref_at_noresolve(cp_index) == vmSymbols::java_lang_invoke_MethodHandle() &&
198 MethodHandles::is_signature_polymorphic_name(SystemDictionary::MethodHandle_klass(),
199 _pool->name_ref_at(cp_index))) {
200 // we may need a resolved_refs entry for the appendix
201 add_invokedynamic_resolved_references_entries(cp_index, cache_index);
202 status = +1;
203 } else {
204 status = -1;
205 }
206 _method_handle_invokers[cp_index] = status;
207 }
208 // We use a special internal bytecode for such methods (if non-static).
209 // The basic reason for this is that such methods need an extra "appendix" argument
210 // to transmit the call site's intended call type.
211 if (status > 0) {
212 (*opc) = (u1)Bytecodes::_invokehandle;
213 }
214 }
215 } else {
216 // Do not need to look at cp_index.
217 if ((*opc) == (u1)Bytecodes::_invokehandle) {
218 (*opc) = (u1)Bytecodes::_invokevirtual;
219 // Ignore corner case of original _invokespecial instruction.
220 // This is safe because (a) the signature polymorphic method was final, and
221 // (b) the implementation of MethodHandle will not call invokespecial on it.
222 }
223 }
224 }
225
226
227 void Rewriter::rewrite_invokedynamic(address bcp, int offset, bool reverse) {
228 address p = bcp + offset;
229 assert(p[-1] == Bytecodes::_invokedynamic, "not invokedynamic bytecode");
230 if (!reverse) {
231 int cp_index = Bytes::get_Java_u2(p);
232 int cache_index = add_invokedynamic_cp_cache_entry(cp_index);
233 int resolved_index = add_invokedynamic_resolved_references_entries(cp_index, cache_index);
234 // Replace the trailing four bytes with a CPC index for the dynamic
235 // call site. Unlike other CPC entries, there is one per bytecode,
236 // not just one per distinct CP entry. In other words, the
237 // CPC-to-CP relation is many-to-one for invokedynamic entries.
238 // This means we must use a larger index size than u2 to address
239 // all these entries. That is the main reason invokedynamic
240 // must have a five-byte instruction format. (Of course, other JVM
241 // implementations can use the bytes for other purposes.)
242 // Note: We use native_u4 format exclusively for 4-byte indexes.
243 Bytes::put_native_u4(p, ConstantPool::encode_invokedynamic_index(cache_index));
244 // add the bcp in case we need to patch this bytecode if we also find a
245 // invokespecial/InterfaceMethodref in the bytecode stream
246 _patch_invokedynamic_bcps->push(p);
247 _patch_invokedynamic_refs->push(resolved_index);
248 } else {
249 int cache_index = ConstantPool::decode_invokedynamic_index(
250 Bytes::get_native_u4(p));
251 // We will reverse the bytecode rewriting _after_ adjusting them.
252 // Adjust the cache index by offset to the invokedynamic entries in the
253 // cpCache plus the delta if the invokedynamic bytecodes were adjusted.
254 int adjustment = cp_cache_delta() + _first_iteration_cp_cache_limit;
255 int cp_index = invokedynamic_cp_cache_entry_pool_index(cache_index - adjustment);
256 assert(_pool->tag_at(cp_index).is_invoke_dynamic(), "wrong index");
257 // zero out 4 bytes
258 Bytes::put_Java_u4(p, 0);
259 Bytes::put_Java_u2(p, cp_index);
260 }
261 }
262
263 void Rewriter::patch_invokedynamic_bytecodes() {
264 // If the end of the cp_cache is the same as after initializing with the
265 // cpool, nothing needs to be done. Invokedynamic bytecodes are at the
266 // correct offsets. ie. no invokespecials added
267 int delta = cp_cache_delta();
268 if (delta > 0) {
269 int length = _patch_invokedynamic_bcps->length();
270 assert(length == _patch_invokedynamic_refs->length(),
271 "lengths should match");
272 for (int i = 0; i < length; i++) {
273 address p = _patch_invokedynamic_bcps->at(i);
274 int cache_index = ConstantPool::decode_invokedynamic_index(
275 Bytes::get_native_u4(p));
276 Bytes::put_native_u4(p, ConstantPool::encode_invokedynamic_index(cache_index + delta));
277
278 // invokedynamic resolved references map also points to cp cache and must
279 // add delta to each.
280 int resolved_index = _patch_invokedynamic_refs->at(i);
281 for (int entry = 0; entry < ConstantPoolCacheEntry::_indy_resolved_references_entries; entry++) {
282 assert(_invokedynamic_references_map[resolved_index+entry] == cache_index,
283 "should be the same index");
284 _invokedynamic_references_map.at_put(resolved_index+entry,
285 cache_index + delta);
286 }
287 }
288 }
289 }
290
291
292 // Rewrite some ldc bytecodes to _fast_aldc
293 void Rewriter::maybe_rewrite_ldc(address bcp, int offset, bool is_wide,
294 bool reverse) {
295 if (!reverse) {
296 assert((*bcp) == (is_wide ? Bytecodes::_ldc_w : Bytecodes::_ldc), "not ldc bytecode");
297 address p = bcp + offset;
298 int cp_index = is_wide ? Bytes::get_Java_u2(p) : (u1)(*p);
299 constantTag tag = _pool->tag_at(cp_index).value();
300 if (tag.is_method_handle() || tag.is_method_type() || tag.is_string()) {
301 int ref_index = cp_entry_to_resolved_references(cp_index);
302 if (is_wide) {
303 (*bcp) = Bytecodes::_fast_aldc_w;
304 assert(ref_index == (u2)ref_index, "index overflow");
305 Bytes::put_native_u2(p, ref_index);
306 } else {
307 (*bcp) = Bytecodes::_fast_aldc;
308 assert(ref_index == (u1)ref_index, "index overflow");
309 (*p) = (u1)ref_index;
310 }
311 }
312 } else {
313 Bytecodes::Code rewritten_bc =
314 (is_wide ? Bytecodes::_fast_aldc_w : Bytecodes::_fast_aldc);
315 if ((*bcp) == rewritten_bc) {
316 address p = bcp + offset;
317 int ref_index = is_wide ? Bytes::get_native_u2(p) : (u1)(*p);
318 int pool_index = resolved_references_entry_to_pool_index(ref_index);
319 if (is_wide) {
320 (*bcp) = Bytecodes::_ldc_w;
321 assert(pool_index == (u2)pool_index, "index overflow");
322 Bytes::put_Java_u2(p, pool_index);
323 } else {
324 (*bcp) = Bytecodes::_ldc;
325 assert(pool_index == (u1)pool_index, "index overflow");
326 (*p) = (u1)pool_index;
327 }
328 }
329 }
330 }
331
332
333 // Rewrites a method given the index_map information
334 void Rewriter::scan_method(Method* method, bool reverse, bool* invokespecial_error) {
335
336 int nof_jsrs = 0;
337 bool has_monitor_bytecodes = false;
338
339 {
340 // We cannot tolerate a GC in this block, because we've
341 // cached the bytecodes in 'code_base'. If the Method*
342 // moves, the bytecodes will also move.
343 No_Safepoint_Verifier nsv;
344 Bytecodes::Code c;
345
346 // Bytecodes and their length
347 const address code_base = method->code_base();
348 const int code_length = method->code_size();
349
350 int bc_length;
351 for (int bci = 0; bci < code_length; bci += bc_length) {
352 address bcp = code_base + bci;
353 int prefix_length = 0;
354 c = (Bytecodes::Code)(*bcp);
355
356 // Since we have the code, see if we can get the length
357 // directly. Some more complicated bytecodes will report
358 // a length of zero, meaning we need to make another method
359 // call to calculate the length.
360 bc_length = Bytecodes::length_for(c);
361 if (bc_length == 0) {
362 bc_length = Bytecodes::length_at(method, bcp);
363
364 // length_at will put us at the bytecode after the one modified
365 // by 'wide'. We don't currently examine any of the bytecodes
366 // modified by wide, but in case we do in the future...
367 if (c == Bytecodes::_wide) {
368 prefix_length = 1;
369 c = (Bytecodes::Code)bcp[1];
370 }
371 }
372
373 assert(bc_length != 0, "impossible bytecode length");
374
375 switch (c) {
376 case Bytecodes::_lookupswitch : {
377 #ifndef CC_INTERP
378 Bytecode_lookupswitch bc(method, bcp);
379 (*bcp) = (
380 bc.number_of_pairs() < BinarySwitchThreshold
381 ? Bytecodes::_fast_linearswitch
382 : Bytecodes::_fast_binaryswitch
383 );
384 #endif
385 break;
386 }
387 case Bytecodes::_fast_linearswitch:
388 case Bytecodes::_fast_binaryswitch: {
389 #ifndef CC_INTERP
390 (*bcp) = Bytecodes::_lookupswitch;
391 #endif
392 break;
393 }
394
395 case Bytecodes::_invokespecial : {
396 rewrite_invokespecial(bcp, prefix_length+1, reverse, invokespecial_error);
397 break;
398 }
399
400 case Bytecodes::_getstatic : // fall through
401 case Bytecodes::_putstatic : // fall through
402 case Bytecodes::_getfield : // fall through
403 case Bytecodes::_putfield : // fall through
404 case Bytecodes::_invokevirtual : // fall through
405 case Bytecodes::_invokestatic :
406 case Bytecodes::_invokeinterface:
407 case Bytecodes::_invokehandle : // if reverse=true
408 rewrite_member_reference(bcp, prefix_length+1, reverse);
409 break;
410 case Bytecodes::_invokedynamic:
411 rewrite_invokedynamic(bcp, prefix_length+1, reverse);
412 break;
413 case Bytecodes::_ldc:
414 case Bytecodes::_fast_aldc: // if reverse=true
415 maybe_rewrite_ldc(bcp, prefix_length+1, false, reverse);
416 break;
417 case Bytecodes::_ldc_w:
418 case Bytecodes::_fast_aldc_w: // if reverse=true
419 maybe_rewrite_ldc(bcp, prefix_length+1, true, reverse);
420 break;
421 case Bytecodes::_jsr : // fall through
422 case Bytecodes::_jsr_w : nof_jsrs++; break;
423 case Bytecodes::_monitorenter : // fall through
424 case Bytecodes::_monitorexit : has_monitor_bytecodes = true; break;
425 }
426 }
427 }
428
429 // Update access flags
430 if (has_monitor_bytecodes) {
431 method->set_has_monitor_bytecodes();
432 }
433
434 // The present of a jsr bytecode implies that the method might potentially
435 // have to be rewritten, so we run the oopMapGenerator on the method
436 if (nof_jsrs > 0) {
437 method->set_has_jsrs();
438 // Second pass will revisit this method.
439 assert(method->has_jsrs(), "didn't we just set this?");
440 }
441 }
442
443 // After constant pool is created, revisit methods containing jsrs.
444 methodHandle Rewriter::rewrite_jsrs(methodHandle method, TRAPS) {
445 ResourceMark rm(THREAD);
446 ResolveOopMapConflicts romc(method);
447 methodHandle original_method = method;
448 method = romc.do_potential_rewrite(CHECK_(methodHandle()));
449 // Update monitor matching info.
450 if (romc.monitor_safe()) {
451 method->set_guaranteed_monitor_matching();
452 }
453
454 return method;
455 }
456
457 void Rewriter::rewrite_bytecodes(TRAPS) {
458 assert(_pool->cache() == NULL, "constant pool cache must not be set yet");
459
460 // determine index maps for Method* rewriting
461 compute_index_maps();
462
463 if (RegisterFinalizersAtInit && _klass->name() == vmSymbols::java_lang_Object()) {
464 bool did_rewrite = false;
465 int i = _methods->length();
466 while (i-- > 0) {
467 Method* method = _methods->at(i);
468 if (method->intrinsic_id() == vmIntrinsics::_Object_init) {
469 // rewrite the return bytecodes of Object.<init> to register the
470 // object for finalization if needed.
471 methodHandle m(THREAD, method);
472 rewrite_Object_init(m, CHECK);
473 did_rewrite = true;
474 break;
475 }
476 }
477 assert(did_rewrite, "must find Object::<init> to rewrite it");
478 }
479
480 // rewrite methods, in two passes
481 int len = _methods->length();
482 bool invokespecial_error = false;
483
484 for (int i = len-1; i >= 0; i--) {
485 Method* method = _methods->at(i);
486 scan_method(method, false, &invokespecial_error);
487 if (invokespecial_error) {
488 // If you get an error here, there is no reversing bytecodes
489 // This exception is stored for this class and no further attempt is
490 // made at verifying or rewriting.
491 THROW_MSG(vmSymbols::java_lang_InternalError(),
492 "This classfile overflows invokespecial for interfaces "
493 "and cannot be loaded");
494 return;
495 }
496 }
497
498 // May have to fix invokedynamic bytecodes if invokestatic/InterfaceMethodref
499 // entries had to be added.
500 patch_invokedynamic_bytecodes();
501 }
502
503 void Rewriter::rewrite(instanceKlassHandle klass, TRAPS) {
504 if (!DumpSharedSpaces) {
505 assert(!MetaspaceShared::is_in_shared_space(klass()), "archive methods must not be rewritten at run time");
506 }
507 ResourceMark rm(THREAD);
508 Rewriter rw(klass, klass->constants(), klass->methods(), CHECK);
509 // (That's all, folks.)
510 }
511
512 Rewriter::Rewriter(instanceKlassHandle klass, constantPoolHandle cpool, Array<Method*>* methods, TRAPS)
513 : _klass(klass),
514 _pool(cpool),
515 _methods(methods)
516 {
517
518 // Rewrite bytecodes - exception here exits.
519 rewrite_bytecodes(CHECK);
520
521 // Stress restoring bytecodes
522 if (StressRewriter) {
523 restore_bytecodes();
524 rewrite_bytecodes(CHECK);
525 }
526
527 // allocate constant pool cache, now that we've seen all the bytecodes
528 make_constant_pool_cache(THREAD);
529
530 // Restore bytecodes to their unrewritten state if there are exceptions
531 // rewriting bytecodes or allocating the cpCache
532 if (HAS_PENDING_EXCEPTION) {
533 restore_bytecodes();
534 return;
535 }
536
537 // Relocate after everything, but still do this under the is_rewritten flag,
538 // so methods with jsrs in custom class lists in aren't attempted to be
539 // rewritten in the RO section of the shared archive.
540 // Relocated bytecodes don't have to be restored, only the cp cache entries
541 int len = _methods->length();
542 for (int i = len-1; i >= 0; i--) {
543 methodHandle m(THREAD, _methods->at(i));
544
545 if (m->has_jsrs()) {
546 m = rewrite_jsrs(m, THREAD);
547 // Restore bytecodes to their unrewritten state if there are exceptions
548 // relocating bytecodes. If some are relocated, that is ok because that
549 // doesn't affect constant pool to cpCache rewriting.
550 if (HAS_PENDING_EXCEPTION) {
551 restore_bytecodes();
552 return;
553 }
554 // Method might have gotten rewritten.
555 methods->at_put(i, m());
556 }
557 }
558 }