1 /*
  2  * Copyright (c) 1997, 2023, 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 "asm/assembler.hpp"
 27 #include "classfile/symbolTable.hpp"
 28 #include "classfile/systemDictionary.hpp"
 29 #include "classfile/vmSymbols.hpp"
 30 #include "memory/oopFactory.hpp"
 31 #include "memory/resourceArea.hpp"
 32 #include "memory/universe.hpp"
 33 #include "oops/instanceKlass.hpp"
 34 #include "oops/klass.inline.hpp"
 35 #include "oops/oop.inline.hpp"
 36 #include "oops/symbol.hpp"
 37 #include "oops/typeArrayKlass.hpp"
 38 #include "oops/inlineKlass.inline.hpp"
 39 #include "runtime/fieldDescriptor.inline.hpp"
 40 #include "runtime/handles.inline.hpp"
 41 #include "runtime/interfaceSupport.inline.hpp"
 42 #include "runtime/safepointVerifiers.hpp"
 43 #include "runtime/sharedRuntime.hpp"
 44 #include "runtime/signature.hpp"
 45 #include "runtime/sharedRuntime.hpp"
 46 
 47 // Implementation of SignatureIterator
 48 
 49 // Signature syntax:
 50 //
 51 // Signature  = "(" {Parameter} ")" ReturnType.
 52 // Parameter  = FieldType.
 53 // ReturnType = FieldType | "V".
 54 // FieldType  = "B" | "C" | "D" | "F" | "I" | "J" | "S" | "Z" | "L" ClassName ";" | "Q" ValueClassName ";" | "[" FieldType.
 55 // ClassName  = string.
 56 
 57 // The ClassName string can be any JVM-style UTF8 string except:
 58 //  - an empty string (the empty string is never a name of any kind)
 59 //  - a string which begins or ends with slash '/' (the package separator)
 60 //  - a string which contains adjacent slashes '//' (no empty package names)
 61 //  - a string which contains a semicolon ';' (the end-delimiter)
 62 //  - a string which contains a left bracket '[' (the array marker)
 63 //  - a string which contains a dot '.' (the external package separator)
 64 //
 65 // Other "meta-looking" characters, such as '(' and '<' and '+',
 66 // are perfectly legitimate within a class name, for the JVM.
 67 // Class names which contain double slashes ('a//b') and non-initial
 68 // brackets ('a[b]') are reserved for possible enrichment of the
 69 // type language.
 70 
 71 void SignatureIterator::set_fingerprint(fingerprint_t fingerprint) {
 72   if (!fp_is_valid(fingerprint)) {
 73     _fingerprint = fingerprint;
 74     _return_type = T_ILLEGAL;
 75   } else if (fingerprint != _fingerprint) {
 76     assert(_fingerprint == zero_fingerprint(), "consistent fingerprint values");
 77     _fingerprint = fingerprint;
 78     _return_type = fp_return_type(fingerprint);
 79   }
 80 }
 81 
 82 BasicType SignatureIterator::return_type() {
 83   if (_return_type == T_ILLEGAL) {
 84     SignatureStream ss(_signature);
 85     ss.skip_to_return_type();
 86     _return_type = ss.type();
 87     assert(_return_type != T_ILLEGAL, "illegal return type");
 88   }
 89   return _return_type;
 90 }
 91 
 92 bool SignatureIterator::fp_is_valid_type(BasicType type, bool for_return_type) {
 93   assert(type != (BasicType)fp_parameters_done, "fingerprint is incorrectly at done");
 94   assert(((int)type & ~fp_parameter_feature_mask) == 0, "fingerprint feature mask yielded non-zero value");
 95   return (is_java_primitive(type) ||
 96           is_reference_type(type) ||
 97           (for_return_type && type == T_VOID));
 98 }
 99 
100 ArgumentSizeComputer::ArgumentSizeComputer(Symbol* signature)
101   : SignatureIterator(signature)
102 {
103   _size = 0;
104   do_parameters_on(this);  // non-virtual template execution
105 }
106 
107 ArgumentCount::ArgumentCount(Symbol* signature)
108   : SignatureIterator(signature)
109 {
110   _size = 0;
111   do_parameters_on(this);  // non-virtual template execution
112 }
113 
114 ReferenceArgumentCount::ReferenceArgumentCount(Symbol* signature)
115   : SignatureIterator(signature)
116 {
117   _refs = 0;
118   do_parameters_on(this);  // non-virtual template execution
119 }
120 
121 #if !defined(_LP64) || defined(ZERO) || defined(ASSERT)
122 static int compute_num_stack_arg_slots(Symbol* signature, int sizeargs, bool is_static) {
123   ResourceMark rm;
124   BasicType* sig_bt = NEW_RESOURCE_ARRAY(BasicType, sizeargs);
125   VMRegPair* regs   = NEW_RESOURCE_ARRAY(VMRegPair, sizeargs);
126 
127   int sig_index = 0;
128   if (!is_static) {
129     sig_bt[sig_index++] = T_OBJECT; // 'this'
130   }
131   for (SignatureStream ss(signature); !ss.at_return_type(); ss.next()) {
132     BasicType t = ss.type();
133     assert(type2size[t] == 1 || type2size[t] == 2, "size is 1 or 2");
134     sig_bt[sig_index++] = t;
135     if (type2size[t] == 2) {
136       sig_bt[sig_index++] = T_VOID;
137     }
138   }
139   assert(sig_index == sizeargs, "sig_index: %d sizeargs: %d", sig_index, sizeargs);
140 
141   return SharedRuntime::java_calling_convention(sig_bt, regs, sizeargs);
142 }
143 #endif
144 
145 void Fingerprinter::compute_fingerprint_and_return_type(bool static_flag) {
146   // See if we fingerprinted this method already
147   if (_method != nullptr) {
148     assert(!static_flag, "must not be passed by caller");
149     static_flag = _method->is_static();
150     _fingerprint = _method->constMethod()->fingerprint();
151 
152     if (_fingerprint != zero_fingerprint()) {
153       _return_type = _method->result_type();
154       assert(is_java_type(_return_type), "return type must be a java type");
155       return;
156     }
157 
158     if (_method->size_of_parameters() > fp_max_size_of_parameters) {
159       _fingerprint = overflow_fingerprint();
160       _method->constMethod()->set_fingerprint(_fingerprint);
161       // as long as we are here compute the return type:
162       _return_type = ResultTypeFinder(_method->signature()).type();
163       assert(is_java_type(_return_type), "return type must be a java type");
164       return;
165     }
166   }
167 
168   // Note:  This will always take the slow path, since _fp==zero_fp.
169   initialize_accumulator();
170   initialize_calling_convention(static_flag);
171   do_parameters_on(this);
172   assert(fp_is_valid_type(_return_type, true), "bad result type");
173 
174   // Fill in the return type and static bits:
175   _accumulator |= _return_type << fp_static_feature_size;
176   if (static_flag) {
177     _accumulator |= fp_is_static_bit;
178   } else {
179     _param_size += 1;  // this is the convention for Method::compute_size_of_parameters
180   }
181 
182 #if defined(_LP64) && !defined(ZERO)
183 #ifdef ASSERT
184   int dbg_stack_arg_slots = compute_num_stack_arg_slots(_signature, _param_size, static_flag);
185   assert(_stack_arg_slots == dbg_stack_arg_slots, "fingerprinter: %d full: %d", _stack_arg_slots, dbg_stack_arg_slots);
186 #endif
187 #else
188   // Fallback: computed _stack_arg_slots is unreliable, compute directly.
189   _stack_arg_slots = compute_num_stack_arg_slots(_signature, _param_size, static_flag);
190 #endif
191 
192   // Detect overflow.  (We counted _param_size correctly.)
193   if (_method == nullptr && _param_size > fp_max_size_of_parameters) {
194     // We did a one-pass computation of argument size, return type,
195     // and fingerprint.
196     _fingerprint = overflow_fingerprint();
197     return;
198   }
199 
200   assert(_shift_count < BitsPerLong,
201          "shift count overflow %d (%d vs. %d): %s",
202          _shift_count, _param_size, fp_max_size_of_parameters,
203          _signature->as_C_string());
204   assert((_accumulator >> _shift_count) == fp_parameters_done, "must be zero");
205 
206   // This is the result, along with _return_type:
207   _fingerprint = _accumulator;
208 
209   // Cache the result on the method itself:
210   if (_method != nullptr) {
211     _method->constMethod()->set_fingerprint(_fingerprint);
212   }
213 }
214 
215 void Fingerprinter::initialize_calling_convention(bool static_flag) {
216   _int_args = 0;
217   _fp_args = 0;
218 
219   if (!static_flag) { // `this` takes up an int register
220     _int_args++;
221   }
222 }
223 
224 void Fingerprinter::do_type_calling_convention(BasicType type) {
225   // We compute the number of slots for stack-passed arguments in compiled calls.
226   // TODO: SharedRuntime::java_calling_convention is the shared code that knows all details
227   // about the platform-specific calling conventions. This method tries to compute the stack
228   // args number... poorly, at least for 32-bit ports and for zero. Current code has the fallback
229   // that recomputes the stack args number from SharedRuntime::java_calling_convention.
230 #if defined(_LP64) && !defined(ZERO)
231   switch (type) {
232   case T_VOID:
233     break;
234   case T_BOOLEAN:
235   case T_CHAR:
236   case T_BYTE:
237   case T_SHORT:
238   case T_INT:
239     if (_int_args < Argument::n_int_register_parameters_j) {
240       _int_args++;
241     } else {
242 #if defined(PPC64) || defined(S390)
243       _stack_arg_slots += 1;
244 #else
245       _stack_arg_slots = align_up(_stack_arg_slots, 2);
246       _stack_arg_slots += 1;
247 #endif // defined(PPC64) || defined(S390)
248     }
249     break;
250   case T_LONG:
251   case T_OBJECT:
252   case T_ARRAY:
253   case T_ADDRESS:
254     if (_int_args < Argument::n_int_register_parameters_j) {
255       _int_args++;
256     } else {
257       _stack_arg_slots = align_up(_stack_arg_slots, 2);
258       _stack_arg_slots += 2;
259     }
260     break;
261   case T_FLOAT:
262     if (_fp_args < Argument::n_float_register_parameters_j) {
263       _fp_args++;
264     } else {
265 #if defined(PPC64) || defined(S390)
266       _stack_arg_slots += 1;
267 #else
268       _stack_arg_slots = align_up(_stack_arg_slots, 2);
269       _stack_arg_slots += 1;
270 #endif // defined(PPC64) || defined(S390)
271     }
272     break;
273   case T_DOUBLE:
274     if (_fp_args < Argument::n_float_register_parameters_j) {
275       _fp_args++;
276     } else {
277       _stack_arg_slots = align_up(_stack_arg_slots, 2);
278       _stack_arg_slots += 2;
279     }
280     break;
281   default:
282     ShouldNotReachHere();
283     break;
284   }
285 #endif
286 }
287 
288 // Implementation of SignatureStream
289 
290 static inline BasicType decode_signature_char(int ch) {
291   switch (ch) {
292 #define EACH_SIG(ch, bt, ignore) \
293     case ch: return bt;
294     SIGNATURE_TYPES_DO(EACH_SIG, ignore)
295 #undef EACH_SIG
296   }
297   return (BasicType)0;
298 }
299 
300 SignatureStream::SignatureStream(const Symbol* signature,
301                                  bool is_method) {
302   assert(!is_method || signature->starts_with(JVM_SIGNATURE_FUNC),
303          "method signature required");
304   _signature = signature;
305   _limit = signature->utf8_length();
306   int oz = (is_method ? _s_method : _s_field);
307   _state = oz;
308   _begin = _end = oz; // skip first '(' in method signatures
309   _array_prefix = 0;  // just for definiteness
310 
311   // assigning java/lang/Object to _previous_name means we can
312   // avoid a number of null checks in the parser
313   _previous_name = vmSymbols::java_lang_Object();
314   _names = nullptr;
315   next();
316 }
317 
318 SignatureStream::~SignatureStream() {
319   if (_previous_name == vmSymbols::java_lang_Object()) {
320     // no names were created
321     assert(_names == nullptr, "_names unexpectedly created");
322     return;
323   }
324 
325   // decrement refcount for names created during signature parsing
326   _previous_name->decrement_refcount();
327   if (_names != nullptr) {
328     for (int i = 0; i < _names->length(); i++) {
329       _names->at(i)->decrement_refcount();
330     }
331   }
332 }
333 
334 inline int SignatureStream::scan_type(BasicType type) {
335   const u1* base = _signature->bytes();
336   int end = _end;
337   int limit = _limit;
338   const u1* tem;
339   switch (type) {
340   case T_OBJECT:
341     tem = (const u1*) memchr(&base[end], JVM_SIGNATURE_ENDCLASS, limit - end);
342     return (tem == nullptr ? limit : pointer_delta_as_int(tem + 1, base));
343 
344   case T_ARRAY:
345     while ((end < limit) && ((char)base[end] == JVM_SIGNATURE_ARRAY)) { end++; }
346     // If we discovered only the string of '[', this means something is wrong.
347     if (end >= limit) {
348       assert(false, "Invalid type detected");
349       return limit;
350     }
351     _array_prefix = end - _end;  // number of '[' chars just skipped
352     if (Signature::has_envelope(base[end])) {
353       tem = (const u1 *) memchr(&base[end], JVM_SIGNATURE_ENDCLASS, limit - end);
354       return (tem == nullptr ? limit : pointer_delta_as_int(tem + 1, base));
355     }
356     // Skipping over a single character for a primitive type.
357     assert(is_java_primitive(decode_signature_char(base[end])), "only primitives expected");
358     return end + 1;
359 
360   default:
361     // Skipping over a single character for a primitive type (or void).
362     assert(!is_reference_type(type), "only primitives or void expected");
363     return end + 1;
364   }
365 }
366 
367 void SignatureStream::next() {
368   const Symbol* sig = _signature;
369   int len = _limit;
370   if (_end >= len) { set_done(); return; }
371   _begin = _end;
372   int ch = sig->char_at(_begin);
373   if (ch == JVM_SIGNATURE_ENDFUNC) {
374     assert(_state == _s_method, "must be in method");
375     _state = _s_method_return;
376     _begin = ++_end;
377     if (_end >= len) { set_done(); return; }
378     ch = sig->char_at(_begin);
379   }
380   BasicType bt = decode_signature_char(ch);
381   assert(ch == type2char(bt), "bad signature char %c/%d", ch, ch);
382   _type = bt;
383   _end = scan_type(bt);
384 }
385 
386 int SignatureStream::skip_whole_array_prefix() {
387   assert(_type == T_ARRAY, "must be");
388 
389   // we are stripping all levels of T_ARRAY,
390   // so we must decode the next character
391   int whole_array_prefix = _array_prefix;
392   int new_begin = _begin + whole_array_prefix;
393   _begin = new_begin;
394   int ch = _signature->char_at(new_begin);
395   BasicType bt = decode_signature_char(ch);
396   assert(ch == type2char(bt), "bad signature char %c/%d", ch, ch);
397   _type = bt;
398   assert(bt != T_VOID && bt != T_ARRAY, "bad signature type");
399   // Don't bother to re-scan, since it won't change the value of _end.
400   return whole_array_prefix;
401 }
402 
403 bool Signature::is_valid_array_signature(const Symbol* sig) {
404   assert(sig->utf8_length() > 1, "this should already have been checked");
405   assert(sig->char_at(0) == JVM_SIGNATURE_ARRAY, "this should already have been checked");
406   // The first character is already checked
407   int i = 1;
408   int len = sig->utf8_length();
409   // First skip all '['s
410   while(i < len - 1 && sig->char_at(i) == JVM_SIGNATURE_ARRAY) i++;
411 
412   // Check type
413   switch(sig->char_at(i)) {
414   case JVM_SIGNATURE_BYTE:
415   case JVM_SIGNATURE_CHAR:
416   case JVM_SIGNATURE_DOUBLE:
417   case JVM_SIGNATURE_FLOAT:
418   case JVM_SIGNATURE_INT:
419   case JVM_SIGNATURE_LONG:
420   case JVM_SIGNATURE_SHORT:
421   case JVM_SIGNATURE_BOOLEAN:
422     // If it is an array, the type is the last character
423     return (i + 1 == len);
424   case JVM_SIGNATURE_CLASS:
425     // If it is an object, the last character must be a ';'
426     return sig->char_at(len - 1) == JVM_SIGNATURE_ENDCLASS;
427   }
428   return false;
429 }
430 
431 BasicType Signature::basic_type(int ch) {
432   BasicType btcode = decode_signature_char(ch);
433   if (btcode == 0)  return T_ILLEGAL;
434   return btcode;
435 }
436 
437 Symbol* Signature::strip_envelope(const Symbol* signature) {
438   assert(has_envelope(signature), "precondition");
439   return SymbolTable::new_symbol((char*) signature->bytes() + 1,
440                                  signature->utf8_length() - 2);
441 }
442 
443 static const int jl_len = 10, object_len = 6, jl_object_len = jl_len + object_len;
444 static const char jl_str[] = "java/lang/";
445 
446 #ifdef ASSERT
447 static bool signature_symbols_sane() {
448   static bool done;
449   if (done)  return true;
450   done = true;
451   // test some tense code that looks for common symbol names:
452   assert(vmSymbols::java_lang_Object()->utf8_length() == jl_object_len &&
453          vmSymbols::java_lang_Object()->starts_with(jl_str, jl_len) &&
454          vmSymbols::java_lang_Object()->ends_with("Object", object_len) &&
455          vmSymbols::java_lang_Object()->is_permanent() &&
456          vmSymbols::java_lang_String()->utf8_length() == jl_object_len &&
457          vmSymbols::java_lang_String()->starts_with(jl_str, jl_len) &&
458          vmSymbols::java_lang_String()->ends_with("String", object_len) &&
459          vmSymbols::java_lang_String()->is_permanent(),
460          "sanity");
461   return true;
462 }
463 #endif //ASSERT
464 
465 // returns a symbol; the caller is responsible for decrementing it
466 Symbol* SignatureStream::find_symbol() {
467   // Create a symbol from for string _begin _end
468   int begin = raw_symbol_begin();
469   int end   = raw_symbol_end();
470 
471   const char* symbol_chars = (const char*)_signature->base() + begin;
472   int len = end - begin;
473 
474   // Quick check for common symbols in signatures
475   assert(signature_symbols_sane(), "incorrect signature sanity check");
476   if (len == jl_object_len &&
477       memcmp(symbol_chars, jl_str, jl_len) == 0) {
478     if (memcmp("String", symbol_chars + jl_len, object_len) == 0) {
479       return vmSymbols::java_lang_String();
480     } else if (memcmp("Object", symbol_chars + jl_len, object_len) == 0) {
481       return vmSymbols::java_lang_Object();
482     }
483   }
484 
485   Symbol* name = _previous_name;
486   if (name->equals(symbol_chars, len)) {
487     return name;
488   }
489 
490   // Save names for cleaning up reference count at the end of
491   // SignatureStream scope.
492   name = SymbolTable::new_symbol(symbol_chars, len);
493 
494   // Only allocate the GrowableArray for the _names buffer if more than
495   // one name is being processed in the signature.
496   if (!_previous_name->is_permanent()) {
497     if (_names == nullptr) {
498       _names = new GrowableArray<Symbol*>(10);
499     }
500     _names->push(_previous_name);
501   }
502   _previous_name = name;
503   return name;
504 }
505 
506 InlineKlass* SignatureStream::as_inline_klass(InstanceKlass* holder) {
507   ThreadInVMfromUnknown tiv;
508   JavaThread* THREAD = JavaThread::current();
509   HandleMark hm(THREAD);
510   Handle class_loader(THREAD, holder->class_loader());
511   Handle protection_domain(THREAD, holder->protection_domain());
512   Klass* k = as_klass(class_loader, protection_domain, SignatureStream::CachedOrNull, THREAD);
513   assert(!HAS_PENDING_EXCEPTION, "Should never throw");
514   if (k != nullptr && k->is_inline_klass()) {
515     return InlineKlass::cast(k);
516   } else {
517     return nullptr;
518   }
519 }
520 
521 Klass* SignatureStream::as_klass(Handle class_loader, Handle protection_domain,
522                                  FailureMode failure_mode, TRAPS) {
523   if (!is_reference()) {
524     return nullptr;
525   }
526   Symbol* name = as_symbol();
527   Klass* k = nullptr;
528   if (failure_mode == ReturnNull) {
529     // Note:  SD::resolve_or_null returns null for most failure modes,
530     // but not all.  Circularity errors, invalid PDs, etc., throw.
531     k = SystemDictionary::resolve_or_null(name, class_loader, protection_domain, CHECK_NULL);
532   } else if (failure_mode == CachedOrNull) {
533     NoSafepointVerifier nsv;  // no loading, now, we mean it!
534     assert(!HAS_PENDING_EXCEPTION, "");
535     k = SystemDictionary::find_instance_klass(THREAD, name, class_loader, protection_domain);
536     // SD::find does not trigger loading, so there should be no throws
537     // Still, bad things can happen, so we CHECK_NULL and ask callers
538     // to do likewise.
539     return k;
540   } else {
541     // The only remaining failure mode is NCDFError.
542     // The test here allows for an additional mode CNFException
543     // if callers need to request the reflective error instead.
544     bool throw_error = (failure_mode == NCDFError);
545     k = SystemDictionary::resolve_or_fail(name, class_loader, protection_domain, throw_error, CHECK_NULL);
546   }
547 
548   return k;
549 }
550 
551 oop SignatureStream::as_java_mirror(Handle class_loader, Handle protection_domain,
552                                     FailureMode failure_mode, TRAPS) {
553   if (!is_reference()) {
554     return Universe::java_mirror(type());
555   }
556   Klass* klass = as_klass(class_loader, protection_domain, failure_mode, CHECK_NULL);
557   if (klass == nullptr) {
558     return nullptr;
559   }
560   return klass->java_mirror();
561 }
562 
563 void SignatureStream::skip_to_return_type() {
564   while (!at_return_type()) {
565     next();
566   }
567 }
568 
569 ResolvingSignatureStream::ResolvingSignatureStream(Symbol* signature,
570                                                    Handle class_loader,
571                                                    Handle protection_domain,
572                                                    bool is_method)
573   : SignatureStream(signature, is_method),
574     _class_loader(class_loader), _protection_domain(protection_domain)
575 {
576   initialize_load_origin(nullptr);
577 }
578 
579 ResolvingSignatureStream::ResolvingSignatureStream(Symbol* signature, Klass* load_origin, bool is_method)
580   : SignatureStream(signature, is_method)
581 {
582   assert(load_origin != nullptr, "");
583   initialize_load_origin(load_origin);
584 }
585 
586 ResolvingSignatureStream::ResolvingSignatureStream(const Method* method)
587   : SignatureStream(method->signature(), true)
588 {
589   initialize_load_origin(method->method_holder());
590 }
591 
592 void ResolvingSignatureStream::cache_handles() {
593   assert(_load_origin != nullptr, "");
594   JavaThread* current = JavaThread::current();
595   _class_loader = Handle(current, _load_origin->class_loader());
596   _protection_domain = Handle(current, _load_origin->protection_domain());
597 }
598 
599 #ifdef ASSERT
600 extern bool signature_constants_sane(); // called from basic_types_init()
601 
602 bool signature_constants_sane() {
603   // for the lookup table, test every 8-bit code point, and then some:
604   for (int i = -256; i <= 256; i++) {
605     int btcode = 0;
606     switch (i) {
607 #define EACH_SIG(ch, bt, ignore) \
608     case ch: { btcode = bt; break; }
609     SIGNATURE_TYPES_DO(EACH_SIG, ignore)
610 #undef EACH_SIG
611     }
612     int btc = decode_signature_char(i);
613     assert(btc == btcode, "misconfigured table: %d => %d not %d", i, btc, btcode);
614   }
615   return true;
616 }
617 
618 bool SignatureVerifier::is_valid_method_signature(const Symbol* sig) {
619   const char* method_sig = (const char*)sig->bytes();
620   ssize_t len = sig->utf8_length();
621   ssize_t index = 0;
622   if (method_sig != nullptr && len > 1 && method_sig[index] == JVM_SIGNATURE_FUNC) {
623     ++index;
624     while (index < len && method_sig[index] != JVM_SIGNATURE_ENDFUNC) {
625       ssize_t res = is_valid_type(&method_sig[index], len - index);
626       if (res == -1) {
627         return false;
628       } else {
629         index += res;
630       }
631     }
632     if (index < len && method_sig[index] == JVM_SIGNATURE_ENDFUNC) {
633       // check the return type
634       ++index;
635       return (is_valid_type(&method_sig[index], len - index) == (len - index));
636     }
637   }
638   return false;
639 }
640 
641 bool SignatureVerifier::is_valid_type_signature(const Symbol* sig) {
642   const char* type_sig = (const char*)sig->bytes();
643   ssize_t len = sig->utf8_length();
644   return (type_sig != nullptr && len >= 1 &&
645           (is_valid_type(type_sig, len) == len));
646 }
647 
648 // Checks to see if the type (not to go beyond 'limit') refers to a valid type.
649 // Returns -1 if it is not, or the index of the next character that is not part
650 // of the type.  The type encoding may end before 'limit' and that's ok.
651 ssize_t SignatureVerifier::is_valid_type(const char* type, ssize_t limit) {
652   ssize_t index = 0;
653 
654   // Iterate over any number of array dimensions
655   while (index < limit && type[index] == JVM_SIGNATURE_ARRAY) ++index;
656   if (index >= limit) {
657     return -1;
658   }
659   switch (type[index]) {
660     case JVM_SIGNATURE_BYTE:
661     case JVM_SIGNATURE_CHAR:
662     case JVM_SIGNATURE_FLOAT:
663     case JVM_SIGNATURE_DOUBLE:
664     case JVM_SIGNATURE_INT:
665     case JVM_SIGNATURE_LONG:
666     case JVM_SIGNATURE_SHORT:
667     case JVM_SIGNATURE_BOOLEAN:
668     case JVM_SIGNATURE_VOID:
669       return index + 1;
670     case JVM_SIGNATURE_CLASS:
671       for (index = index + 1; index < limit; ++index) {
672         char c = type[index];
673         switch (c) {
674           case JVM_SIGNATURE_ENDCLASS:
675             return index + 1;
676           case '\0': case JVM_SIGNATURE_DOT: case JVM_SIGNATURE_ARRAY:
677             return -1;
678           default: ; // fall through
679         }
680       }
681       // fall through
682     default: ; // fall through
683   }
684   return -1;
685 }
686 
687 #endif // ASSERT
688 
689 // Adds an argument to the signature
690 void SigEntry::add_entry(GrowableArray<SigEntry>* sig, BasicType bt, Symbol* symbol, int offset) {
691   sig->append(SigEntry(bt, offset, symbol));
692   if (bt == T_LONG || bt == T_DOUBLE) {
693     sig->append(SigEntry(T_VOID, offset, symbol)); // Longs and doubles take two stack slots
694   }
695 }
696 
697 // Returns true if the argument at index 'i' is not an inline type delimiter
698 bool SigEntry::skip_value_delimiters(const GrowableArray<SigEntry>* sig, int i) {
699   return (sig->at(i)._bt != T_METADATA &&
700           (sig->at(i)._bt != T_VOID || sig->at(i-1)._bt == T_LONG || sig->at(i-1)._bt == T_DOUBLE));
701 }
702 
703 // Fill basic type array from signature array
704 int SigEntry::fill_sig_bt(const GrowableArray<SigEntry>* sig, BasicType* sig_bt) {
705   int count = 0;
706   for (int i = 0; i < sig->length(); i++) {
707     if (skip_value_delimiters(sig, i)) {
708       sig_bt[count++] = sig->at(i)._bt;
709     }
710   }
711   return count;
712 }
713 
714 // Create a temporary symbol from the signature array
715 TempNewSymbol SigEntry::create_symbol(const GrowableArray<SigEntry>* sig) {
716   ResourceMark rm;
717   int length = sig->length();
718   char* sig_str = NEW_RESOURCE_ARRAY(char, 2*length + 3);
719   int idx = 0;
720   sig_str[idx++] = '(';
721   for (int i = 0; i < length; i++) {
722     BasicType bt = sig->at(i)._bt;
723     if (bt == T_METADATA || bt == T_VOID) {
724       // Ignore
725     } else {
726       if (bt == T_ARRAY) {
727         bt = T_OBJECT; // We don't know the element type, treat as Object
728       }
729       sig_str[idx++] = type2char(bt);
730       if (bt == T_OBJECT) {
731         sig_str[idx++] = ';';
732       }
733     }
734   }
735   sig_str[idx++] = ')';
736   // Add a dummy return type. It won't be used but SignatureStream needs it.
737   sig_str[idx++] = 'V';
738   sig_str[idx++] = '\0';
739   return SymbolTable::new_symbol(sig_str);
740 }