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src/hotspot/share/classfile/stackMapTable.cpp

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110   bool result = true;
111   if (match) {
112     // Has direct control flow from last instruction, need to match the two
113     // frames.
114     result = frame->is_assignable_to(stackmap_frame,
115         ctx, CHECK_VERIFY_(frame->verifier(), result));
116   }
117   if (update) {
118     // Use the frame in stackmap table as current frame
119     int lsize = stackmap_frame->locals_size();
120     int ssize = stackmap_frame->stack_size();
121     if (frame->locals_size() > lsize || frame->stack_size() > ssize) {
122       // Make sure unused type array items are all _bogus_type.
123       frame->reset();
124     }
125     frame->set_locals_size(lsize);
126     frame->copy_locals(stackmap_frame);
127     frame->set_stack_size(ssize);
128     frame->copy_stack(stackmap_frame);
129     frame->set_flags(stackmap_frame->flags());

130   }
131   return result;
132 }
133 
134 void StackMapTable::check_jump_target(
135     StackMapFrame* frame, int32_t target, TRAPS) const {
136   ErrorContext ctx;
137   bool match = match_stackmap(
138     frame, target, true, false, &ctx, CHECK_VERIFY(frame->verifier()));
139   if (!match || (target < 0 || target >= _code_length)) {
140     frame->verifier()->verify_error(ctx,
141         "Inconsistent stackmap frames at branch target %d", target);
142   }
143 }
144 
145 void StackMapTable::print_on(outputStream* str) const {
146   str->indent().print_cr("StackMapTable: frame_count = %d", _frame_count);
147   str->indent().print_cr("table = { ");
148   {
149     streamIndentor si(str);
150     for (int32_t i = 0; i < _frame_count; ++i) {
151       _frame_array->at(i)->print_on(str);
152     }
153   }
154   str->print_cr(" }");
155 }
156 
157 StackMapReader::StackMapReader(ClassVerifier* v, StackMapStream* stream,
158                                char* code_data, int32_t code_len,
159                                StackMapFrame* init_frame,
160                                u2 max_locals, u2 max_stack, TRAPS) :

161                                   _verifier(v), _stream(stream), _code_data(code_data),
162                                   _code_length(code_len), _parsed_frame_count(0),
163                                   _prev_frame(init_frame), _max_locals(max_locals),
164                                   _max_stack(max_stack), _first(true) {

165   methodHandle m = v->method();
166   if (m->has_stackmap_table()) {
167     _cp = constantPoolHandle(THREAD, m->constants());
168     _frame_count = _stream->get_u2(CHECK);
169   } else {
170     // There's no stackmap table present. Frame count and size are 0.
171     _frame_count = 0;
172   }
173 }
174 
175 int32_t StackMapReader::chop(
176     VerificationType* locals, int32_t length, int32_t chops) {
177   if (locals == nullptr) return -1;
178   int32_t pos = length - 1;
179   for (int32_t i=0; i<chops; i++) {
180     if (locals[pos].is_category2_2nd()) {
181       pos -= 2;
182     } else {
183       pos --;
184     }

186   }
187   return pos+1;
188 }
189 
190 #define CHECK_NT CHECK_(VerificationType::bogus_type())
191 
192 VerificationType StackMapReader::parse_verification_type(u1* flags, TRAPS) {
193   u1 tag = _stream->get_u1(CHECK_NT);
194   if (tag < (u1)ITEM_UninitializedThis) {
195     return VerificationType::from_tag(tag);
196   }
197   if (tag == ITEM_Object) {
198     u2 class_index = _stream->get_u2(CHECK_NT);
199     int nconstants = _cp->length();
200     if ((class_index <= 0 || class_index >= nconstants) ||
201         (!_cp->tag_at(class_index).is_klass() &&
202          !_cp->tag_at(class_index).is_unresolved_klass())) {
203       _stream->stackmap_format_error("bad class index", THREAD);
204       return VerificationType::bogus_type();
205     }
206     return VerificationType::reference_type(_cp->klass_name_at(class_index));

207   }
208   if (tag == ITEM_UninitializedThis) {
209     if (flags != nullptr) {
210       *flags |= FLAG_THIS_UNINIT;
211     }
212     return VerificationType::uninitialized_this_type();
213   }
214   if (tag == ITEM_Uninitialized) {
215     u2 offset = _stream->get_u2(CHECK_NT);
216     if (offset >= _code_length ||
217         _code_data[offset] != ClassVerifier::NEW_OFFSET) {
218       _verifier->class_format_error(
219         "StackMapTable format error: bad offset for Uninitialized");
220       return VerificationType::bogus_type();
221     }
222     return VerificationType::uninitialized_type(offset);
223   }
224   _stream->stackmap_format_error("bad verification type", THREAD);
225   return VerificationType::bogus_type();
226 }
227 
228 StackMapFrame* StackMapReader::next(TRAPS) {
229   _parsed_frame_count++;
230   check_size(CHECK_NULL);
231   StackMapFrame* frame = next_helper(CHECK_VERIFY_(_verifier, nullptr));
232   if (frame != nullptr) {
233     check_offset(frame);
234     if (frame->verifier()->has_error()) {
235       return nullptr;
236     }
237     _prev_frame = frame;
238   }
239   return frame;
240 }
241 
242 StackMapFrame* StackMapReader::next_helper(TRAPS) {
243   StackMapFrame* frame;
244   int offset;
245   VerificationType* locals = nullptr;
246   u1 frame_type = _stream->get_u1(CHECK_NULL);














































247   if (frame_type < 64) {
248     // same_frame
249     if (_first) {
250       offset = frame_type;
251       // Can't share the locals array since that is updated by the verifier.
252       if (_prev_frame->locals_size() > 0) {
253         locals = NEW_RESOURCE_ARRAY_IN_THREAD(
254           THREAD, VerificationType, _prev_frame->locals_size());
255       }
256     } else {
257       offset = _prev_frame->offset() + frame_type + 1;
258       locals = _prev_frame->locals();
259     }
260     frame = new StackMapFrame(
261       offset, _prev_frame->flags(), _prev_frame->locals_size(), 0,
262       _max_locals, _max_stack, locals, nullptr, _verifier);

263     if (_first && locals != nullptr) {
264       frame->copy_locals(_prev_frame);
265     }
266     _first = false;
267     return frame;
268   }
269   if (frame_type < 128) {
270     // same_locals_1_stack_item_frame
271     if (_first) {
272       offset = frame_type - 64;
273       // Can't share the locals array since that is updated by the verifier.
274       if (_prev_frame->locals_size() > 0) {
275         locals = NEW_RESOURCE_ARRAY_IN_THREAD(
276           THREAD, VerificationType, _prev_frame->locals_size());
277       }
278     } else {
279       offset = _prev_frame->offset() + frame_type - 63;
280       locals = _prev_frame->locals();
281     }
282     VerificationType* stack = NEW_RESOURCE_ARRAY_IN_THREAD(
283       THREAD, VerificationType, 2);
284     u2 stack_size = 1;
285     stack[0] = parse_verification_type(nullptr, CHECK_VERIFY_(_verifier, nullptr));
286     if (stack[0].is_category2()) {
287       stack[1] = stack[0].to_category2_2nd();
288       stack_size = 2;
289     }
290     check_verification_type_array_size(
291       stack_size, _max_stack, CHECK_VERIFY_(_verifier, nullptr));
292     frame = new StackMapFrame(
293       offset, _prev_frame->flags(), _prev_frame->locals_size(), stack_size,
294       _max_locals, _max_stack, locals, stack, _verifier);

295     if (_first && locals != nullptr) {
296       frame->copy_locals(_prev_frame);
297     }
298     _first = false;
299     return frame;
300   }
301 
302   u2 offset_delta = _stream->get_u2(CHECK_NULL);
303 
304   if (frame_type < SAME_LOCALS_1_STACK_ITEM_EXTENDED) {
305     // reserved frame types
306     _stream->stackmap_format_error(
307       "reserved frame type", CHECK_VERIFY_(_verifier, nullptr));
308   }
309 
310   if (frame_type == SAME_LOCALS_1_STACK_ITEM_EXTENDED) {
311     // same_locals_1_stack_item_frame_extended
312     if (_first) {
313       offset = offset_delta;
314       // Can't share the locals array since that is updated by the verifier.
315       if (_prev_frame->locals_size() > 0) {
316         locals = NEW_RESOURCE_ARRAY_IN_THREAD(
317           THREAD, VerificationType, _prev_frame->locals_size());
318       }
319     } else {
320       offset = _prev_frame->offset() + offset_delta + 1;
321       locals = _prev_frame->locals();
322     }
323     VerificationType* stack = NEW_RESOURCE_ARRAY_IN_THREAD(
324       THREAD, VerificationType, 2);
325     u2 stack_size = 1;
326     stack[0] = parse_verification_type(nullptr, CHECK_VERIFY_(_verifier, nullptr));
327     if (stack[0].is_category2()) {
328       stack[1] = stack[0].to_category2_2nd();
329       stack_size = 2;
330     }
331     check_verification_type_array_size(
332       stack_size, _max_stack, CHECK_VERIFY_(_verifier, nullptr));
333     frame = new StackMapFrame(
334       offset, _prev_frame->flags(), _prev_frame->locals_size(), stack_size,
335       _max_locals, _max_stack, locals, stack, _verifier);

336     if (_first && locals != nullptr) {
337       frame->copy_locals(_prev_frame);
338     }
339     _first = false;
340     return frame;
341   }
342 
343   if (frame_type <= SAME_EXTENDED) {
344     // chop_frame or same_frame_extended
345     locals = _prev_frame->locals();
346     int length = _prev_frame->locals_size();
347     int chops = SAME_EXTENDED - frame_type;
348     int new_length = length;
349     u1 flags = _prev_frame->flags();
350     if (chops != 0) {
351       new_length = chop(locals, length, chops);
352       check_verification_type_array_size(
353         new_length, _max_locals, CHECK_VERIFY_(_verifier, nullptr));
354       // Recompute flags since uninitializedThis could have been chopped.
355       flags = 0;

357         if (locals[i].is_uninitialized_this()) {
358           flags |= FLAG_THIS_UNINIT;
359           break;
360         }
361       }
362     }
363     if (_first) {
364       offset = offset_delta;
365       // Can't share the locals array since that is updated by the verifier.
366       if (new_length > 0) {
367         locals = NEW_RESOURCE_ARRAY_IN_THREAD(
368           THREAD, VerificationType, new_length);
369       } else {
370         locals = nullptr;
371       }
372     } else {
373       offset = _prev_frame->offset() + offset_delta + 1;
374     }
375     frame = new StackMapFrame(
376       offset, flags, new_length, 0, _max_locals, _max_stack,
377       locals, nullptr, _verifier);

378     if (_first && locals != nullptr) {
379       frame->copy_locals(_prev_frame);
380     }
381     _first = false;
382     return frame;
383   } else if (frame_type < SAME_EXTENDED + 4) {
384     // append_frame
385     int appends = frame_type - SAME_EXTENDED;
386     int real_length = _prev_frame->locals_size();
387     int new_length = real_length + appends*2;
388     locals = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, VerificationType, new_length);
389     VerificationType* pre_locals = _prev_frame->locals();
390     for (int i = 0; i < _prev_frame->locals_size(); i++) {
391       locals[i] = pre_locals[i];
392     }
393     u1 flags = _prev_frame->flags();
394     for (int i = 0; i < appends; i++) {
395       locals[real_length] = parse_verification_type(&flags, CHECK_NULL);
396       if (locals[real_length].is_category2()) {
397         locals[real_length + 1] = locals[real_length].to_category2_2nd();
398         ++real_length;
399       }
400       ++real_length;
401     }
402     check_verification_type_array_size(
403       real_length, _max_locals, CHECK_VERIFY_(_verifier, nullptr));
404     if (_first) {
405       offset = offset_delta;
406     } else {
407       offset = _prev_frame->offset() + offset_delta + 1;
408     }
409     frame = new StackMapFrame(
410       offset, flags, real_length, 0, _max_locals,
411       _max_stack, locals, nullptr, _verifier);

412     _first = false;
413     return frame;
414   }
415   if (frame_type == FULL) {
416     // full_frame
417     u1 flags = 0;
418     u2 locals_size = _stream->get_u2(CHECK_NULL);
419     int real_locals_size = 0;
420     if (locals_size > 0) {
421       locals = NEW_RESOURCE_ARRAY_IN_THREAD(
422         THREAD, VerificationType, locals_size*2);
423     }
424     for (int i = 0; i < locals_size; i++) {
425       locals[real_locals_size] = parse_verification_type(&flags, CHECK_NULL);
426       if (locals[real_locals_size].is_category2()) {
427         locals[real_locals_size + 1] =
428           locals[real_locals_size].to_category2_2nd();
429         ++real_locals_size;
430       }
431       ++real_locals_size;

439       stack = NEW_RESOURCE_ARRAY_IN_THREAD(
440         THREAD, VerificationType, stack_size*2);
441     }
442     for (int i = 0; i < stack_size; i++) {
443       stack[real_stack_size] = parse_verification_type(nullptr, CHECK_NULL);
444       if (stack[real_stack_size].is_category2()) {
445         stack[real_stack_size + 1] = stack[real_stack_size].to_category2_2nd();
446         ++real_stack_size;
447       }
448       ++real_stack_size;
449     }
450     check_verification_type_array_size(
451       real_stack_size, _max_stack, CHECK_VERIFY_(_verifier, nullptr));
452     if (_first) {
453       offset = offset_delta;
454     } else {
455       offset = _prev_frame->offset() + offset_delta + 1;
456     }
457     frame = new StackMapFrame(
458       offset, flags, real_locals_size, real_stack_size,
459       _max_locals, _max_stack, locals, stack, _verifier);

460     _first = false;
461     return frame;
462   }
463 
464   _stream->stackmap_format_error(
465     "reserved frame type", CHECK_VERIFY_(_prev_frame->verifier(), nullptr));
466   return nullptr;
467 }

110   bool result = true;
111   if (match) {
112     // Has direct control flow from last instruction, need to match the two
113     // frames.
114     result = frame->is_assignable_to(stackmap_frame,
115         ctx, CHECK_VERIFY_(frame->verifier(), result));
116   }
117   if (update) {
118     // Use the frame in stackmap table as current frame
119     int lsize = stackmap_frame->locals_size();
120     int ssize = stackmap_frame->stack_size();
121     if (frame->locals_size() > lsize || frame->stack_size() > ssize) {
122       // Make sure unused type array items are all _bogus_type.
123       frame->reset();
124     }
125     frame->set_locals_size(lsize);
126     frame->copy_locals(stackmap_frame);
127     frame->set_stack_size(ssize);
128     frame->copy_stack(stackmap_frame);
129     frame->set_flags(stackmap_frame->flags());
130     frame->set_assert_unset_fields(stackmap_frame->assert_unset_fields());
131   }
132   return result;
133 }
134 
135 void StackMapTable::check_jump_target(
136     StackMapFrame* frame, int32_t target, TRAPS) const {
137   ErrorContext ctx;
138   bool match = match_stackmap(
139     frame, target, true, false, &ctx, CHECK_VERIFY(frame->verifier()));
140   if (!match || (target < 0 || target >= _code_length)) {
141     frame->verifier()->verify_error(ctx,
142         "Inconsistent stackmap frames at branch target %d", target);
143   }
144 }
145 
146 void StackMapTable::print_on(outputStream* str) const {
147   str->indent().print_cr("StackMapTable: frame_count = %d", _frame_count);
148   str->indent().print_cr("table = { ");
149   {
150     streamIndentor si(str);
151     for (int32_t i = 0; i < _frame_count; ++i) {
152       _frame_array->at(i)->print_on(str);
153     }
154   }
155   str->print_cr(" }");
156 }
157 
158 StackMapReader::StackMapReader(ClassVerifier* v, StackMapStream* stream,
159                                char* code_data, int32_t code_len,
160                                StackMapFrame* init_frame,
161                                u2 max_locals, u2 max_stack,
162                                StackMapFrame::AssertUnsetFieldTable* initial_strict_fields, TRAPS) :
163                                   _verifier(v), _stream(stream), _code_data(code_data),
164                                   _code_length(code_len), _parsed_frame_count(0),
165                                   _prev_frame(init_frame), _max_locals(max_locals),
166                                   _max_stack(max_stack), _assert_unset_fields_buffer(initial_strict_fields),
167                                   _first(true) {
168   methodHandle m = v->method();
169   if (m->has_stackmap_table()) {
170     _cp = constantPoolHandle(THREAD, m->constants());
171     _frame_count = _stream->get_u2(CHECK);
172   } else {
173     // There's no stackmap table present. Frame count and size are 0.
174     _frame_count = 0;
175   }
176 }
177 
178 int32_t StackMapReader::chop(
179     VerificationType* locals, int32_t length, int32_t chops) {
180   if (locals == nullptr) return -1;
181   int32_t pos = length - 1;
182   for (int32_t i=0; i<chops; i++) {
183     if (locals[pos].is_category2_2nd()) {
184       pos -= 2;
185     } else {
186       pos --;
187     }

189   }
190   return pos+1;
191 }
192 
193 #define CHECK_NT CHECK_(VerificationType::bogus_type())
194 
195 VerificationType StackMapReader::parse_verification_type(u1* flags, TRAPS) {
196   u1 tag = _stream->get_u1(CHECK_NT);
197   if (tag < (u1)ITEM_UninitializedThis) {
198     return VerificationType::from_tag(tag);
199   }
200   if (tag == ITEM_Object) {
201     u2 class_index = _stream->get_u2(CHECK_NT);
202     int nconstants = _cp->length();
203     if ((class_index <= 0 || class_index >= nconstants) ||
204         (!_cp->tag_at(class_index).is_klass() &&
205          !_cp->tag_at(class_index).is_unresolved_klass())) {
206       _stream->stackmap_format_error("bad class index", THREAD);
207       return VerificationType::bogus_type();
208     }
209     Symbol* klass_name = _cp->klass_name_at(class_index);
210     return VerificationType::reference_type(klass_name);
211   }
212   if (tag == ITEM_UninitializedThis) {
213     if (flags != nullptr) {
214       *flags |= FLAG_THIS_UNINIT;
215     }
216     return VerificationType::uninitialized_this_type();
217   }
218   if (tag == ITEM_Uninitialized) {
219     u2 offset = _stream->get_u2(CHECK_NT);
220     if (offset >= _code_length ||
221         _code_data[offset] != ClassVerifier::NEW_OFFSET) {
222       _verifier->class_format_error(
223         "StackMapTable format error: bad offset for Uninitialized");
224       return VerificationType::bogus_type();
225     }
226     return VerificationType::uninitialized_type(offset);
227   }
228   _stream->stackmap_format_error("bad verification type", THREAD);
229   return VerificationType::bogus_type();
230 }
231 
232 StackMapFrame* StackMapReader::next(TRAPS) {
233   _parsed_frame_count++;
234   check_size(CHECK_NULL);
235   StackMapFrame* frame = next_helper(CHECK_VERIFY_(_verifier, nullptr));
236   if (frame != nullptr) {
237     check_offset(frame);
238     if (frame->verifier()->has_error()) {
239       return nullptr;
240     }
241     _prev_frame = frame;
242   }
243   return frame;
244 }
245 
246 StackMapFrame* StackMapReader::next_helper(TRAPS) {
247   StackMapFrame* frame;
248   int offset;
249   VerificationType* locals = nullptr;
250   u1 frame_type = _stream->get_u1(CHECK_NULL);
251   if (frame_type == EARLY_LARVAL) {
252     u2 num_unset_fields = _stream->get_u2(CHECK_NULL);
253     StackMapFrame::AssertUnsetFieldTable* new_fields = new StackMapFrame::AssertUnsetFieldTable();
254 
255     for (u2 i = 0; i < num_unset_fields; i++) {
256       u2 index = _stream->get_u2(CHECK_NULL);
257       Symbol* name = _cp->symbol_at(_cp->name_ref_index_at(index));
258       Symbol* sig = _cp->symbol_at(_cp->signature_ref_index_at(index));
259       NameAndSig tmp(name, sig);
260 
261       if (!_prev_frame->assert_unset_fields()->contains(tmp)) {
262         ResourceMark rm(THREAD);
263         log_info(verification)("Field %s%s is not found among initial strict instance fields", name->as_C_string(), sig->as_C_string());
264         StackMapFrame::print_strict_fields(_prev_frame->assert_unset_fields());
265         _prev_frame->verifier()->verify_error(
266             ErrorContext::bad_strict_fields(_prev_frame->offset(), _prev_frame),
267             "Strict fields not a subset of initial strict instance fields: %s:%s", name->as_C_string(), sig->as_C_string());
268       } else {
269         new_fields->put(tmp, false);
270       }
271     }
272 
273     // Only modify strict instance fields the frame has uninitialized this
274     if (_prev_frame->flag_this_uninit()) {
275       _assert_unset_fields_buffer = _prev_frame->merge_unset_fields(new_fields);
276     } else if (new_fields->number_of_entries() > 0) {
277       _prev_frame->verifier()->verify_error(
278         ErrorContext::bad_strict_fields(_prev_frame->offset(), _prev_frame),
279         "Cannot have uninitialized strict fields after class initialization");
280     }
281 
282     // Continue reading frame data
283     if (at_end()) {
284       _prev_frame->verifier()->verify_error(
285         ErrorContext::bad_strict_fields(_prev_frame->offset(), _prev_frame),
286         "Early larval frame must be followed by a base frame");
287     }
288 
289     frame_type = _stream->get_u1(CHECK_NULL);
290     if (frame_type == EARLY_LARVAL) {
291       _prev_frame->verifier()->verify_error(
292         ErrorContext::bad_strict_fields(_prev_frame->offset(), _prev_frame),
293         "Early larval frame must be followed by a base frame");
294     }
295   }
296 
297   if (frame_type < 64) {
298     // same_frame
299     if (_first) {
300       offset = frame_type;
301       // Can't share the locals array since that is updated by the verifier.
302       if (_prev_frame->locals_size() > 0) {
303         locals = NEW_RESOURCE_ARRAY_IN_THREAD(
304           THREAD, VerificationType, _prev_frame->locals_size());
305       }
306     } else {
307       offset = _prev_frame->offset() + frame_type + 1;
308       locals = _prev_frame->locals();
309     }
310     frame = new StackMapFrame(
311       offset, _prev_frame->flags(), _prev_frame->locals_size(), 0,
312       _max_locals, _max_stack, locals, nullptr,
313       _assert_unset_fields_buffer, _verifier);
314     if (_first && locals != nullptr) {
315       frame->copy_locals(_prev_frame);
316     }
317     _first = false;
318     return frame;
319   }
320   if (frame_type < 128) {
321     // same_locals_1_stack_item_frame
322     if (_first) {
323       offset = frame_type - 64;
324       // Can't share the locals array since that is updated by the verifier.
325       if (_prev_frame->locals_size() > 0) {
326         locals = NEW_RESOURCE_ARRAY_IN_THREAD(
327           THREAD, VerificationType, _prev_frame->locals_size());
328       }
329     } else {
330       offset = _prev_frame->offset() + frame_type - 63;
331       locals = _prev_frame->locals();
332     }
333     VerificationType* stack = NEW_RESOURCE_ARRAY_IN_THREAD(
334       THREAD, VerificationType, 2);
335     u2 stack_size = 1;
336     stack[0] = parse_verification_type(nullptr, CHECK_VERIFY_(_verifier, nullptr));
337     if (stack[0].is_category2()) {
338       stack[1] = stack[0].to_category2_2nd();
339       stack_size = 2;
340     }
341     check_verification_type_array_size(
342       stack_size, _max_stack, CHECK_VERIFY_(_verifier, nullptr));
343     frame = new StackMapFrame(
344       offset, _prev_frame->flags(), _prev_frame->locals_size(), stack_size,
345       _max_locals, _max_stack, locals, stack,
346       _assert_unset_fields_buffer, _verifier);
347     if (_first && locals != nullptr) {
348       frame->copy_locals(_prev_frame);
349     }
350     _first = false;
351     return frame;
352   }
353 
354   u2 offset_delta = _stream->get_u2(CHECK_NULL);
355 
356   if (frame_type < EARLY_LARVAL) {
357     // reserved frame types
358     _stream->stackmap_format_error(
359       "reserved frame type", CHECK_VERIFY_(_verifier, nullptr));
360   }
361 
362   if (frame_type == SAME_LOCALS_1_STACK_ITEM_EXTENDED) {
363     // same_locals_1_stack_item_frame_extended
364     if (_first) {
365       offset = offset_delta;
366       // Can't share the locals array since that is updated by the verifier.
367       if (_prev_frame->locals_size() > 0) {
368         locals = NEW_RESOURCE_ARRAY_IN_THREAD(
369           THREAD, VerificationType, _prev_frame->locals_size());
370       }
371     } else {
372       offset = _prev_frame->offset() + offset_delta + 1;
373       locals = _prev_frame->locals();
374     }
375     VerificationType* stack = NEW_RESOURCE_ARRAY_IN_THREAD(
376       THREAD, VerificationType, 2);
377     u2 stack_size = 1;
378     stack[0] = parse_verification_type(nullptr, CHECK_VERIFY_(_verifier, nullptr));
379     if (stack[0].is_category2()) {
380       stack[1] = stack[0].to_category2_2nd();
381       stack_size = 2;
382     }
383     check_verification_type_array_size(
384       stack_size, _max_stack, CHECK_VERIFY_(_verifier, nullptr));
385     frame = new StackMapFrame(
386       offset, _prev_frame->flags(), _prev_frame->locals_size(), stack_size,
387       _max_locals, _max_stack, locals, stack,
388       _assert_unset_fields_buffer, _verifier);
389     if (_first && locals != nullptr) {
390       frame->copy_locals(_prev_frame);
391     }
392     _first = false;
393     return frame;
394   }
395 
396   if (frame_type <= SAME_EXTENDED) {
397     // chop_frame or same_frame_extended
398     locals = _prev_frame->locals();
399     int length = _prev_frame->locals_size();
400     int chops = SAME_EXTENDED - frame_type;
401     int new_length = length;
402     u1 flags = _prev_frame->flags();
403     if (chops != 0) {
404       new_length = chop(locals, length, chops);
405       check_verification_type_array_size(
406         new_length, _max_locals, CHECK_VERIFY_(_verifier, nullptr));
407       // Recompute flags since uninitializedThis could have been chopped.
408       flags = 0;

410         if (locals[i].is_uninitialized_this()) {
411           flags |= FLAG_THIS_UNINIT;
412           break;
413         }
414       }
415     }
416     if (_first) {
417       offset = offset_delta;
418       // Can't share the locals array since that is updated by the verifier.
419       if (new_length > 0) {
420         locals = NEW_RESOURCE_ARRAY_IN_THREAD(
421           THREAD, VerificationType, new_length);
422       } else {
423         locals = nullptr;
424       }
425     } else {
426       offset = _prev_frame->offset() + offset_delta + 1;
427     }
428     frame = new StackMapFrame(
429       offset, flags, new_length, 0, _max_locals, _max_stack,
430       locals, nullptr,
431       _assert_unset_fields_buffer, _verifier);
432     if (_first && locals != nullptr) {
433       frame->copy_locals(_prev_frame);
434     }
435     _first = false;
436     return frame;
437   } else if (frame_type < SAME_EXTENDED + 4) {
438     // append_frame
439     int appends = frame_type - SAME_EXTENDED;
440     int real_length = _prev_frame->locals_size();
441     int new_length = real_length + appends*2;
442     locals = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, VerificationType, new_length);
443     VerificationType* pre_locals = _prev_frame->locals();
444     for (int i = 0; i < _prev_frame->locals_size(); i++) {
445       locals[i] = pre_locals[i];
446     }
447     u1 flags = _prev_frame->flags();
448     for (int i = 0; i < appends; i++) {
449       locals[real_length] = parse_verification_type(&flags, CHECK_NULL);
450       if (locals[real_length].is_category2()) {
451         locals[real_length + 1] = locals[real_length].to_category2_2nd();
452         ++real_length;
453       }
454       ++real_length;
455     }
456     check_verification_type_array_size(
457       real_length, _max_locals, CHECK_VERIFY_(_verifier, nullptr));
458     if (_first) {
459       offset = offset_delta;
460     } else {
461       offset = _prev_frame->offset() + offset_delta + 1;
462     }
463     frame = new StackMapFrame(
464       offset, flags, real_length, 0, _max_locals,
465       _max_stack, locals, nullptr,
466       _assert_unset_fields_buffer, _verifier);
467     _first = false;
468     return frame;
469   }
470   if (frame_type == FULL) {
471     // full_frame
472     u1 flags = 0;
473     u2 locals_size = _stream->get_u2(CHECK_NULL);
474     int real_locals_size = 0;
475     if (locals_size > 0) {
476       locals = NEW_RESOURCE_ARRAY_IN_THREAD(
477         THREAD, VerificationType, locals_size*2);
478     }
479     for (int i = 0; i < locals_size; i++) {
480       locals[real_locals_size] = parse_verification_type(&flags, CHECK_NULL);
481       if (locals[real_locals_size].is_category2()) {
482         locals[real_locals_size + 1] =
483           locals[real_locals_size].to_category2_2nd();
484         ++real_locals_size;
485       }
486       ++real_locals_size;

494       stack = NEW_RESOURCE_ARRAY_IN_THREAD(
495         THREAD, VerificationType, stack_size*2);
496     }
497     for (int i = 0; i < stack_size; i++) {
498       stack[real_stack_size] = parse_verification_type(nullptr, CHECK_NULL);
499       if (stack[real_stack_size].is_category2()) {
500         stack[real_stack_size + 1] = stack[real_stack_size].to_category2_2nd();
501         ++real_stack_size;
502       }
503       ++real_stack_size;
504     }
505     check_verification_type_array_size(
506       real_stack_size, _max_stack, CHECK_VERIFY_(_verifier, nullptr));
507     if (_first) {
508       offset = offset_delta;
509     } else {
510       offset = _prev_frame->offset() + offset_delta + 1;
511     }
512     frame = new StackMapFrame(
513       offset, flags, real_locals_size, real_stack_size,
514       _max_locals, _max_stack, locals, stack,
515       _assert_unset_fields_buffer, _verifier);
516     _first = false;
517     return frame;
518   }
519 
520   _stream->stackmap_format_error(
521     "reserved frame type", CHECK_VERIFY_(_prev_frame->verifier(), nullptr));
522   return nullptr;
523 }
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