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