1 /*
  2  * Copyright (c) 1999, 2019, 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 "ci/ciConstant.hpp"
 27 #include "ci/ciField.hpp"
 28 #include "ci/ciKlass.hpp"
 29 #include "ci/ciObjArrayKlass.hpp"
 30 #include "ci/ciStreams.hpp"
 31 #include "ci/ciSymbols.hpp"
 32 #include "ci/ciUtilities.inline.hpp"
 33 #include "runtime/handles.inline.hpp"
 34 
 35 // ciExceptionHandlerStream
 36 //
 37 // Walk over some selected set of a methods exception handlers.
 38 
 39 // ------------------------------------------------------------------
 40 // ciExceptionHandlerStream::count
 41 //
 42 // How many exception handlers are there in this stream?
 43 //
 44 // Implementation note: Compiler2 needs this functionality, so I had
 45 int ciExceptionHandlerStream::count() {
 46   int save_pos = _pos;
 47   int save_end = _end;
 48 
 49   int count = 0;
 50 
 51   _pos = -1;
 52   _end = _method->_handler_count;
 53 
 54 
 55   next();
 56   while (!is_done()) {
 57     count++;
 58     next();
 59   }
 60 
 61   _pos = save_pos;
 62   _end = save_end;
 63 
 64   return count;
 65 }
 66 
 67 int ciExceptionHandlerStream::count_remaining() {
 68   int save_pos = _pos;
 69   int save_end = _end;
 70 
 71   int count = 0;
 72 
 73   while (!is_done()) {
 74     count++;
 75     next();
 76   }
 77 
 78   _pos = save_pos;
 79   _end = save_end;
 80 
 81   return count;
 82 }
 83 
 84 // ciBytecodeStream
 85 //
 86 // The class is used to iterate over the bytecodes of a method.
 87 // It hides the details of constant pool structure/access by
 88 // providing accessors for constant pool items.
 89 
 90 // ------------------------------------------------------------------
 91 // ciBytecodeStream::next_wide_or_table
 92 //
 93 // Special handling for switch ops
 94 Bytecodes::Code ciBytecodeStream::next_wide_or_table(Bytecodes::Code bc) {
 95   switch (bc) {                // Check for special bytecode handling
 96   case Bytecodes::_wide:
 97     // Special handling for the wide bytcode
 98     // Get following bytecode; do not return wide
 99     assert(Bytecodes::Code(_pc[0]) == Bytecodes::_wide, "");
100     bc = Bytecodes::java_code(_raw_bc = (Bytecodes::Code)_pc[1]);
101     assert(Bytecodes::wide_length_for(bc) > 2, "must make progress");
102     _pc += Bytecodes::wide_length_for(bc);
103     _was_wide = _pc;              // Flag last wide bytecode found
104     assert(is_wide(), "accessor works right");
105     break;
106 
107   case Bytecodes::_lookupswitch:
108     _pc++;                      // Skip wide bytecode
109     _pc += (_start-_pc)&3;      // Word align
110     _table_base = (jint*)_pc;   // Capture for later usage
111                                 // table_base[0] is default far_dest
112     // Table has 2 lead elements (default, length), then pairs of u4 values.
113     // So load table length, and compute address at end of table
114     _pc = (address)&_table_base[2+ 2*Bytes::get_Java_u4((address)&_table_base[1])];
115     break;
116 
117   case Bytecodes::_tableswitch: {
118     _pc++;                      // Skip wide bytecode
119     _pc += (_start-_pc)&3;      // Word align
120     _table_base = (jint*)_pc;   // Capture for later usage
121                                 // table_base[0] is default far_dest
122     int lo = Bytes::get_Java_u4((address)&_table_base[1]);// Low bound
123     int hi = Bytes::get_Java_u4((address)&_table_base[2]);// High bound
124     int len = hi - lo + 1;      // Dense table size
125     _pc = (address)&_table_base[3+len]; // Skip past table
126     break;
127   }
128 
129   default:
130     fatal("unhandled bytecode");
131   }
132   return bc;
133 }
134 
135 // ------------------------------------------------------------------
136 // ciBytecodeStream::reset_to_bci
137 void ciBytecodeStream::reset_to_bci( int bci ) {
138   _bc_start=_was_wide=0;
139   _pc = _start+bci;
140 }
141 
142 // ------------------------------------------------------------------
143 // ciBytecodeStream::force_bci
144 void ciBytecodeStream::force_bci(int bci) {
145   if (bci < 0) {
146     reset_to_bci(0);
147     _bc_start = _start + bci;
148     _bc = EOBC();
149   } else {
150     reset_to_bci(bci);
151     next();
152   }
153 }
154 
155 
156 // ------------------------------------------------------------------
157 // Constant pool access
158 // ------------------------------------------------------------------
159 
160 // ------------------------------------------------------------------
161 // ciBytecodeStream::get_klass_index
162 //
163 // If this bytecodes references a klass, return the index of the
164 // referenced klass.
165 int ciBytecodeStream::get_klass_index() const {
166   switch(cur_bc()) {
167   case Bytecodes::_ldc:
168     return get_index_u1();
169   case Bytecodes::_ldc_w:
170   case Bytecodes::_ldc2_w:
171   case Bytecodes::_checkcast:
172   case Bytecodes::_instanceof:
173   case Bytecodes::_anewarray:
174   case Bytecodes::_multianewarray:
175   case Bytecodes::_new:
176   case Bytecodes::_aconst_init:
177   case Bytecodes::_newarray:
178     return get_index_u2();
179   default:
180     ShouldNotReachHere();
181     return 0;
182   }
183 }
184 
185 // ------------------------------------------------------------------
186 // ciBytecodeStream::get_klass
187 //
188 // If this bytecode is a new, newarray, multianewarray, instanceof,
189 // or checkcast, get the referenced klass.
190 ciKlass* ciBytecodeStream::get_klass(bool& will_link) {
191   VM_ENTRY_MARK;
192   constantPoolHandle cpool(THREAD, _method->get_Method()->constants());
193   return CURRENT_ENV->get_klass_by_index(cpool, get_klass_index(), will_link, _holder);
194 }
195 
196 // ciBytecodeStream::get_klass
197 //
198 // If this bytecode is a new, newarray, multianewarray, instanceof,
199 // or checkcast, get the referenced klass. Retuns an unloaded ciKlass
200 // if the referenced klass is not accessible.
201 ciKlass* ciBytecodeStream::get_klass() {
202   bool will_link;
203   ciKlass* klass = get_klass(will_link);
204   if (!will_link && klass->is_loaded()) { // klass not accessible
205     VM_ENTRY_MARK;
206     klass = CURRENT_ENV->get_unloaded_klass(_holder, klass->name());
207   }
208   return klass;
209 }
210 
211 // ------------------------------------------------------------------
212 // ciBytecodeStream::is_inline_klass
213 //
214 // Check if the klass is an inline klass.
215 bool ciBytecodeStream::has_Q_signature() const {
216   VM_ENTRY_MARK;
217   constantPoolHandle cpool(THREAD, _method->get_Method()->constants());
218   return CURRENT_ENV->has_Q_signature(cpool, get_klass_index());
219 }
220 
221 // ------------------------------------------------------------------
222 // ciBytecodeStream::get_constant_raw_index
223 //
224 // If this bytecode is one of the ldc variants, get the index of the
225 // referenced constant.
226 int ciBytecodeStream::get_constant_raw_index() const {
227   // work-alike for Bytecode_loadconstant::raw_index()
228   switch (cur_bc()) {
229   case Bytecodes::_ldc:
230     return get_index_u1();
231   case Bytecodes::_ldc_w:
232   case Bytecodes::_ldc2_w:
233     return get_index_u2();
234   default:
235     ShouldNotReachHere();
236     return 0;
237   }
238 }
239 
240 // ------------------------------------------------------------------
241 // ciBytecodeStream::get_constant_pool_index
242 // Decode any reference index into a regular pool index.
243 int ciBytecodeStream::get_constant_pool_index() const {
244   // work-alike for Bytecode_loadconstant::pool_index()
245   int index = get_constant_raw_index();
246   if (has_cache_index()) {
247     VM_ENTRY_MARK;
248     constantPoolHandle cpool(THREAD, _method->get_Method()->constants());
249     return cpool->object_to_cp_index(index);
250   }
251   return index;
252 }
253 
254 // ------------------------------------------------------------------
255 // ciBytecodeStream::get_constant
256 //
257 // If this bytecode is one of the ldc variants, get the referenced
258 // constant.
259 ciConstant ciBytecodeStream::get_constant() {
260   VM_ENTRY_MARK;
261   constantPoolHandle cpool(THREAD, _method->get_Method()->constants());
262   int pool_index = get_constant_raw_index();
263   int cache_index = -1;
264   if (has_cache_index()) {
265     cache_index = pool_index;
266     pool_index = cpool->object_to_cp_index(cache_index);
267   } else if (cpool->tag_at(pool_index).is_dynamic_constant() ||
268              cpool->tag_at(pool_index).is_dynamic_constant_in_error()) {
269     // Condy with primitive type is not quickened, so the index into resolved reference cache should be reconstructed.
270     assert(is_java_primitive(cpool->basic_type_for_constant_at(pool_index)), "not quickened");
271     cache_index = cpool->cp_to_object_index(pool_index);
272   }
273   return CURRENT_ENV->get_constant_by_index(cpool, pool_index, cache_index, _holder);
274 }
275 
276 // ------------------------------------------------------------------
277 // ciBytecodeStream::get_constant_pool_tag
278 //
279 // If this bytecode is one of the ldc variants, get the referenced
280 // constant.
281 constantTag ciBytecodeStream::get_constant_pool_tag(int index) const {
282   VM_ENTRY_MARK;
283   return _method->get_Method()->constants()->constant_tag_at(index);
284 }
285 
286 // ------------------------------------------------------------------
287 // ciBytecodeStream::get_raw_pool_tag
288 //
289 constantTag ciBytecodeStream::get_raw_pool_tag_at(int index) const {
290   VM_ENTRY_MARK;
291   return _method->get_Method()->constants()->tag_at(index);
292 }
293 
294 // ------------------------------------------------------------------
295 // ciBytecodeStream::get_basic_type_for_constant_at
296 //
297 BasicType ciBytecodeStream::get_basic_type_for_constant_at(int index) const {
298   VM_ENTRY_MARK;
299   return _method->get_Method()->constants()->basic_type_for_constant_at(index);
300 }
301 
302 // ------------------------------------------------------------------
303 // ciBytecodeStream::get_field_index
304 //
305 // If this is a field access bytecode, get the constant pool
306 // index of the referenced field.
307 int ciBytecodeStream::get_field_index() {
308   assert(cur_bc() == Bytecodes::_getfield ||
309          cur_bc() == Bytecodes::_putfield ||
310          cur_bc() == Bytecodes::_getstatic ||
311          cur_bc() == Bytecodes::_putstatic ||
312          cur_bc() == Bytecodes::_withfield, "wrong bc");
313   return get_index_u2_cpcache();
314 }
315 
316 
317 // ------------------------------------------------------------------
318 // ciBytecodeStream::get_field
319 //
320 // If this bytecode is one of get_field, get_static, put_field,
321 // or put_static, get the referenced field.
322 ciField* ciBytecodeStream::get_field(bool& will_link) {
323   ciField* f = CURRENT_ENV->get_field_by_index(_holder, get_field_index());
324   will_link = f->will_link(_method, _bc);
325   return f;
326 }
327 
328 
329 // ------------------------------------------------------------------
330 // ciBytecodeStream::get_declared_field_holder
331 //
332 // Get the declared holder of the currently referenced field.
333 //
334 // Usage note: the holder() of a ciField class returns the canonical
335 // holder of the field, rather than the holder declared in the
336 // bytecodes.
337 //
338 // There is no "will_link" result passed back.  The user is responsible
339 // for checking linkability when retrieving the associated field.
340 ciInstanceKlass* ciBytecodeStream::get_declared_field_holder() {
341   VM_ENTRY_MARK;
342   constantPoolHandle cpool(THREAD, _method->get_Method()->constants());
343   int holder_index = get_field_holder_index();
344   bool ignore;
345   return CURRENT_ENV->get_klass_by_index(cpool, holder_index, ignore, _holder)
346       ->as_instance_klass();
347 }
348 
349 // ------------------------------------------------------------------
350 // ciBytecodeStream::get_field_holder_index
351 //
352 // Get the constant pool index of the declared holder of the field
353 // referenced by the current bytecode.  Used for generating
354 // deoptimization information.
355 int ciBytecodeStream::get_field_holder_index() {
356   GUARDED_VM_ENTRY(
357     ConstantPool* cpool = _holder->get_instanceKlass()->constants();
358     return cpool->klass_ref_index_at(get_field_index());
359   )
360 }
361 
362 // ------------------------------------------------------------------
363 // ciBytecodeStream::get_method_index
364 //
365 // If this is a method invocation bytecode, get the constant pool
366 // index of the invoked method.
367 int ciBytecodeStream::get_method_index() {
368   assert(Bytecodes::is_invoke(cur_bc()), "invalid bytecode: %s", Bytecodes::name(cur_bc()));
369   if (has_index_u4())
370     return get_index_u4();  // invokedynamic
371   return get_index_u2_cpcache();
372 }
373 
374 // ------------------------------------------------------------------
375 // ciBytecodeStream::get_method
376 //
377 // If this is a method invocation bytecode, get the invoked method.
378 // Additionally return the declared signature to get more concrete
379 // type information if required (Cf. invokedynamic and invokehandle).
380 ciMethod* ciBytecodeStream::get_method(bool& will_link, ciSignature* *declared_signature_result) {
381   VM_ENTRY_MARK;
382   ciEnv* env = CURRENT_ENV;
383   constantPoolHandle cpool(THREAD, _method->get_Method()->constants());
384   ciMethod* m = env->get_method_by_index(cpool, get_method_index(), cur_bc(), _holder);
385   will_link = m->is_loaded();
386 
387   // Use the signature stored in the CP cache to create a signature
388   // with correct types (in respect to class loaders).
389   //
390   // In classic Java (before Java 7) there is never the slightest
391   // difference between the signature at the call site and that of the
392   // method.  Such a difference would have been a type error in the
393   // JVM.
394   //
395   // Now there are a few circumstances where the signature of a call
396   // site (which controls the outgoing stacked arguments) can differ
397   // from the signature of the method (which controls the receipt of
398   // those arguments at the method entry point).
399   //
400   // A. The signatures can differ if the callee is a static method and
401   // the caller thinks it is calling a non-static method (VH.get).
402   // This requires the method signature to have an explicit leading
403   // argument for the implicit 'this', not present at the call site.
404   //
405   // B. The call site can have less specific parameter types than the
406   // method, allowing loosely-typed code to handle strongly-typed
407   // methods.  This happens with linkToStatic and related linker
408   // commands.  Obviously the loosely-typed code has to ensure that
409   // the strongly typed method's invariants are respected, and this is
410   // done by issuing dynamic casts.
411   //
412   // C. The call site can have more specific parameter types than the
413   // method, allowing loosely-typed methods to handle strongly-typed
414   // requests.
415   //
416   // D. There are corresponding effects with return values, such as
417   // boolean method returning an int to an int-receiving call site,
418   // even though the method thought it returned just a boolean.
419   //
420   // E. The calling sequence at a particular call site may add an
421   // "appendix" argument not mentioned in the call site signature.  It
422   // is expected by the method signature, though, and this adds to the
423   // method's arity, even after 'this' parameter effects (A) are
424   // discounted.  Appendixes are used by invokehandle and
425   // invokedynamic instructions.
426   //
427   // F. A linker method (linkToStatic, etc.) can also take an extra
428   // argument, a MemberName which routes the call to a concrete
429   // strongly-typed method.  In this case the linker method may also
430   // differ in any of the ways A-D.  The eventual method will ignore
431   // the presence of the extra argument.
432   //
433   // None of these changes to calling sequences requires an argument
434   // to be moved or reformatted in any way.  This works because all
435   // references look alike to the JVM, as do all primitives (except
436   // float/long/double).  Another required property of the JVM is
437   // that, if a trailing argument is added or dropped, the placement
438   // of other arguments does not change.  This allows cases E and F to
439   // work smoothly, against without any moving or reformatting,
440   // despite the arity change.
441   //
442   if (has_local_signature()) {
443     Symbol* local_signature = cpool->symbol_at(get_method_signature_index(cpool));
444     ciSymbol* sig_sym  = env->get_symbol(local_signature);
445     ciKlass* pool_holder = env->get_klass(cpool->pool_holder());
446     ciSignature* call_site_sig = new (env->arena()) ciSignature(pool_holder, cpool, sig_sym);
447     // Examples of how the call site signature can differ from the method's own signature:
448     //
449     //  meth = static jboolean java.lang.invoke.VarHandleGuards.guard_LII_Z(jobject, jobject, jint, jint, jobject)
450     //  msig = (Ljava/lang/invoke/VarHandle;Ljava/lang/Object;IILjava/lang/invoke/VarHandle$AccessDescriptor;)Z
451     //  call = (Ljava/util/concurrent/locks/AbstractQueuedSynchronizer;II)Z
452     //
453     //  meth = static jobject java.lang.invoke.LambdaForm$MH/0x0000000800066840.linkToTargetMethod(jobject, jobject)
454     //  msig = (Ljava/lang/Object;Ljava/lang/Object;)Ljava/lang/Object;
455     //  call = (Ljava/lang/String;)Ljava/util/function/Predicate;
456     //
457     (*declared_signature_result) = call_site_sig;
458 
459   } else {
460     // We can just use the method's own signature.  It may differ from the call site, but not by much.
461     //
462     // Examples of how the call site signature can differ from the method's signature:
463     //
464     // meth = static final native jint java.lang.invoke.MethodHandle.linkToStatic(jobject, jobject, jint, jint, jobject)
465     // msig = (Ljava/lang/Object;Ljava/lang/Object;IILjava/lang/invoke/MemberName;)I
466     // call = (Ljava/lang/invoke/VarHandle;Ljava/lang/Object;IILjava/lang/invoke/MemberName;)Z
467     //
468     // meth = final native jint java.lang.invoke.MethodHandle.invokeBasic(jobject, jobject, jint, jint)
469     // msig = (Ljava/lang/Object;Ljava/lang/Object;II)I
470     // call = (Ljava/lang/invoke/VarHandle;Ljava/lang/Object;II)Z
471     //
472     (*declared_signature_result) = m->signature();
473   }
474   return m;
475 }
476 
477 // ------------------------------------------------------------------
478 // ciBytecodeStream::has_appendix
479 //
480 // Returns true if there is an appendix argument stored in the
481 // constant pool cache at the current bci.
482 bool ciBytecodeStream::has_appendix() {
483   VM_ENTRY_MARK;
484   constantPoolHandle cpool(THREAD, _method->get_Method()->constants());
485   return ConstantPool::has_appendix_at_if_loaded(cpool, get_method_index());
486 }
487 
488 // ------------------------------------------------------------------
489 // ciBytecodeStream::get_appendix
490 //
491 // Return the appendix argument stored in the constant pool cache at
492 // the current bci.
493 ciObject* ciBytecodeStream::get_appendix() {
494   VM_ENTRY_MARK;
495   constantPoolHandle cpool(THREAD, _method->get_Method()->constants());
496   oop appendix_oop = ConstantPool::appendix_at_if_loaded(cpool, get_method_index());
497   return CURRENT_ENV->get_object(appendix_oop);
498 }
499 
500 // ------------------------------------------------------------------
501 // ciBytecodeStream::has_local_signature
502 //
503 // Returns true if the method stored in the constant
504 // pool cache at the current bci has a local signature.
505 bool ciBytecodeStream::has_local_signature() {
506   GUARDED_VM_ENTRY(
507     constantPoolHandle cpool(Thread::current(), _method->get_Method()->constants());
508     return ConstantPool::has_local_signature_at_if_loaded(cpool, get_method_index());
509   )
510 }
511 
512 // ------------------------------------------------------------------
513 // ciBytecodeStream::get_declared_method_holder
514 //
515 // Get the declared holder of the currently referenced method.
516 //
517 // Usage note: the holder() of a ciMethod class returns the canonical
518 // holder of the method, rather than the holder declared in the
519 // bytecodes.
520 //
521 // There is no "will_link" result passed back.  The user is responsible
522 // for checking linkability when retrieving the associated method.
523 ciKlass* ciBytecodeStream::get_declared_method_holder() {
524   VM_ENTRY_MARK;
525   constantPoolHandle cpool(THREAD, _method->get_Method()->constants());
526   bool ignore;
527   // report as MethodHandle for invokedynamic, which is syntactically classless
528   if (cur_bc() == Bytecodes::_invokedynamic) {
529     return CURRENT_ENV->MethodHandle_klass();
530   }
531   return CURRENT_ENV->get_klass_by_index(cpool, get_method_holder_index(), ignore, _holder);
532 }
533 
534 // ------------------------------------------------------------------
535 // ciBytecodeStream::get_method_holder_index
536 //
537 // Get the constant pool index of the declared holder of the method
538 // referenced by the current bytecode.  Used for generating
539 // deoptimization information.
540 int ciBytecodeStream::get_method_holder_index() {
541   ConstantPool* cpool = _method->get_Method()->constants();
542   return cpool->klass_ref_index_at(get_method_index());
543 }
544 
545 // ------------------------------------------------------------------
546 // ciBytecodeStream::get_method_signature_index
547 //
548 // Get the constant pool index of the signature of the method
549 // referenced by the current bytecode.  Used for generating
550 // deoptimization information.
551 int ciBytecodeStream::get_method_signature_index(const constantPoolHandle& cpool) {
552   GUARDED_VM_ENTRY(
553     const int method_index = get_method_index();
554     const int name_and_type_index = cpool->name_and_type_ref_index_at(method_index);
555     return cpool->signature_ref_index_at(name_and_type_index);
556   )
557 }
558