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