1 /*
  2  * Copyright (c) 1997, 2022, 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 != NULL) {
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   _stack_arg_slots = align_up(_stack_arg_slots, 2);
184 #ifdef ASSERT
185   int dbg_stack_arg_slots = compute_num_stack_arg_slots(_signature, _param_size, static_flag);
186   assert(_stack_arg_slots == dbg_stack_arg_slots, "fingerprinter: %d full: %d", _stack_arg_slots, dbg_stack_arg_slots);
187 #endif
188 #else
189   // Fallback: computed _stack_arg_slots is unreliable, compute directly.
190   _stack_arg_slots = compute_num_stack_arg_slots(_signature, _param_size, static_flag);
191 #endif
192 
193   // Detect overflow.  (We counted _param_size correctly.)
194   if (_method == NULL && _param_size > fp_max_size_of_parameters) {
195     // We did a one-pass computation of argument size, return type,
196     // and fingerprint.
197     _fingerprint = overflow_fingerprint();
198     return;
199   }
200 
201   assert(_shift_count < BitsPerLong,
202          "shift count overflow %d (%d vs. %d): %s",
203          _shift_count, _param_size, fp_max_size_of_parameters,
204          _signature->as_C_string());
205   assert((_accumulator >> _shift_count) == fp_parameters_done, "must be zero");
206 
207   // This is the result, along with _return_type:
208   _fingerprint = _accumulator;
209 
210   // Cache the result on the method itself:
211   if (_method != NULL) {
212     _method->constMethod()->set_fingerprint(_fingerprint);
213   }
214 }
215 
216 void Fingerprinter::initialize_calling_convention(bool static_flag) {
217   _int_args = 0;
218   _fp_args = 0;
219 
220   if (!static_flag) { // `this` takes up an int register
221     _int_args++;
222   }
223 }
224 
225 void Fingerprinter::do_type_calling_convention(BasicType type) {
226   // We compute the number of slots for stack-passed arguments in compiled calls.
227   // TODO: SharedRuntime::java_calling_convention is the shared code that knows all details
228   // about the platform-specific calling conventions. This method tries to compute the stack
229   // args number... poorly, at least for 32-bit ports and for zero. Current code has the fallback
230   // that recomputes the stack args number from SharedRuntime::java_calling_convention.
231 #if defined(_LP64) && !defined(ZERO)
232   switch (type) {
233   case T_VOID:
234     break;
235   case T_BOOLEAN:
236   case T_CHAR:
237   case T_BYTE:
238   case T_SHORT:
239   case T_INT:
240 #if defined(PPC64) || defined(S390)
241     if (_int_args < Argument::n_int_register_parameters_j) {
242       _int_args++;
243     } else {
244       _stack_arg_slots += 1;
245     }
246     break;
247 #endif // defined(PPC64) || defined(S390)
248   case T_LONG:
249   case T_OBJECT:
250   case T_ARRAY:
251   case T_ADDRESS:
252   case T_PRIMITIVE_OBJECT:
253     if (_int_args < Argument::n_int_register_parameters_j) {
254       _int_args++;
255     } else {
256       PPC64_ONLY(_stack_arg_slots = align_up(_stack_arg_slots, 2));
257       S390_ONLY(_stack_arg_slots = align_up(_stack_arg_slots, 2));
258       _stack_arg_slots += 2;
259     }
260     break;
261   case T_FLOAT:
262 #if defined(PPC64) || defined(S390)
263     if (_fp_args < Argument::n_float_register_parameters_j) {
264       _fp_args++;
265     } else {
266       _stack_arg_slots += 1;
267     }
268     break;
269 #endif // defined(PPC64) || defined(S390)
270   case T_DOUBLE:
271     if (_fp_args < Argument::n_float_register_parameters_j) {
272       _fp_args++;
273     } else {
274       PPC64_ONLY(_stack_arg_slots = align_up(_stack_arg_slots, 2));
275       S390_ONLY(_stack_arg_slots = align_up(_stack_arg_slots, 2));
276       _stack_arg_slots += 2;
277     }
278     break;
279   default:
280     ShouldNotReachHere();
281     break;
282   }
283 #endif
284 }
285 
286 // Implementation of SignatureStream
287 
288 static inline BasicType decode_signature_char(int ch) {
289   switch (ch) {
290 #define EACH_SIG(ch, bt, ignore) \
291     case ch: return bt;
292     SIGNATURE_TYPES_DO(EACH_SIG, ignore)
293 #undef EACH_SIG
294   }
295   return (BasicType)0;
296 }
297 
298 SignatureStream::SignatureStream(const Symbol* signature,
299                                  bool is_method) {
300   assert(!is_method || signature->starts_with(JVM_SIGNATURE_FUNC),
301          "method signature required");
302   _signature = signature;
303   _limit = signature->utf8_length();
304   int oz = (is_method ? _s_method : _s_field);
305   _state = oz;
306   _begin = _end = oz; // skip first '(' in method signatures
307   _array_prefix = 0;  // just for definiteness
308 
309   // assigning java/lang/Object to _previous_name means we can
310   // avoid a number of NULL checks in the parser
311   _previous_name = vmSymbols::java_lang_Object();
312   _names = NULL;
313   next();
314 }
315 
316 SignatureStream::~SignatureStream() {
317   if (_previous_name == vmSymbols::java_lang_Object()) {
318     // no names were created
319     assert(_names == NULL, "_names unexpectedly created");
320     return;
321   }
322 
323   // decrement refcount for names created during signature parsing
324   _previous_name->decrement_refcount();
325   if (_names != NULL) {
326     for (int i = 0; i < _names->length(); i++) {
327       _names->at(i)->decrement_refcount();
328     }
329   }
330 }
331 
332 inline int SignatureStream::scan_type(BasicType type) {
333   const u1* base = _signature->bytes();
334   int end = _end;
335   int limit = _limit;
336   const u1* tem;
337   switch (type) {
338   case T_OBJECT:
339   case T_PRIMITIVE_OBJECT:
340     tem = (const u1*) memchr(&base[end], JVM_SIGNATURE_ENDCLASS, limit - end);
341     return (tem == NULL ? limit : tem + 1 - base);
342 
343   case T_ARRAY:
344     while ((end < limit) && ((char)base[end] == JVM_SIGNATURE_ARRAY)) { end++; }
345     // If we discovered only the string of '[', this means something is wrong.
346     if (end >= limit) {
347       assert(false, "Invalid type detected");
348       return limit;
349     }
350     _array_prefix = end - _end;  // number of '[' chars just skipped
351     if (Signature::has_envelope(base[end])) {
352       tem = (const u1 *) memchr(&base[end], JVM_SIGNATURE_ENDCLASS, limit - end);
353       return (tem == NULL ? limit : tem + 1 - base);
354     }
355     // Skipping over a single character for a primitive type.
356     assert(is_java_primitive(decode_signature_char(base[end])), "only primitives expected");
357     return end + 1;
358 
359   default:
360     // Skipping over a single character for a primitive type (or void).
361     assert(!is_reference_type(type), "only primitives or void expected");
362     return end + 1;
363   }
364 }
365 
366 void SignatureStream::next() {
367   const Symbol* sig = _signature;
368   int len = _limit;
369   if (_end >= len) { set_done(); return; }
370   _begin = _end;
371   int ch = sig->char_at(_begin);
372   if (ch == JVM_SIGNATURE_ENDFUNC) {
373     assert(_state == _s_method, "must be in method");
374     _state = _s_method_return;
375     _begin = ++_end;
376     if (_end >= len) { set_done(); return; }
377     ch = sig->char_at(_begin);
378   }
379   BasicType bt = decode_signature_char(ch);
380   assert(ch == type2char(bt), "bad signature char %c/%d", ch, ch);
381   _type = bt;
382   _end = scan_type(bt);
383 }
384 
385 int SignatureStream::skip_whole_array_prefix() {
386   assert(_type == T_ARRAY, "must be");
387 
388   // we are stripping all levels of T_ARRAY,
389   // so we must decode the next character
390   int whole_array_prefix = _array_prefix;
391   int new_begin = _begin + whole_array_prefix;
392   _begin = new_begin;
393   int ch = _signature->char_at(new_begin);
394   BasicType bt = decode_signature_char(ch);
395   assert(ch == type2char(bt), "bad signature char %c/%d", ch, ch);
396   _type = bt;
397   assert(bt != T_VOID && bt != T_ARRAY, "bad signature type");
398   // Don't bother to re-scan, since it won't change the value of _end.
399   return whole_array_prefix;
400 }
401 
402 bool Signature::is_valid_array_signature(const Symbol* sig) {
403   assert(sig->utf8_length() > 1, "this should already have been checked");
404   assert(sig->char_at(0) == JVM_SIGNATURE_ARRAY, "this should already have been checked");
405   // The first character is already checked
406   int i = 1;
407   int len = sig->utf8_length();
408   // First skip all '['s
409   while(i < len - 1 && sig->char_at(i) == JVM_SIGNATURE_ARRAY) i++;
410 
411   // Check type
412   switch(sig->char_at(i)) {
413   case JVM_SIGNATURE_BYTE:
414   case JVM_SIGNATURE_CHAR:
415   case JVM_SIGNATURE_DOUBLE:
416   case JVM_SIGNATURE_FLOAT:
417   case JVM_SIGNATURE_INT:
418   case JVM_SIGNATURE_LONG:
419   case JVM_SIGNATURE_SHORT:
420   case JVM_SIGNATURE_BOOLEAN:
421     // If it is an array, the type is the last character
422     return (i + 1 == len);
423   case JVM_SIGNATURE_CLASS:
424   case JVM_SIGNATURE_PRIMITIVE_OBJECT:
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 == NULL) {
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   Handle class_loader(THREAD, holder->class_loader());
510   Handle protection_domain(THREAD, holder->protection_domain());
511   Klass* k = as_klass(class_loader, protection_domain, SignatureStream::CachedOrNull, THREAD);
512   assert(!HAS_PENDING_EXCEPTION, "Should never throw");
513   if (k != NULL && k->is_inline_klass()) {
514     return InlineKlass::cast(k);
515   } else {
516     return NULL;
517   }
518 }
519 
520 Klass* SignatureStream::as_klass(Handle class_loader, Handle protection_domain,
521                                  FailureMode failure_mode, TRAPS) {
522   if (!is_reference()) {
523     return NULL;
524   }
525   Symbol* name = as_symbol();
526   Klass* k = NULL;
527   if (failure_mode == ReturnNull) {
528     // Note:  SD::resolve_or_null returns NULL for most failure modes,
529     // but not all.  Circularity errors, invalid PDs, etc., throw.
530     k = SystemDictionary::resolve_or_null(name, class_loader, protection_domain, CHECK_NULL);
531   } else if (failure_mode == CachedOrNull) {
532     NoSafepointVerifier nsv;  // no loading, now, we mean it!
533     assert(!HAS_PENDING_EXCEPTION, "");
534     k = SystemDictionary::find_instance_klass(THREAD, name, class_loader, protection_domain);
535     // SD::find does not trigger loading, so there should be no throws
536     // Still, bad things can happen, so we CHECK_NULL and ask callers
537     // to do likewise.
538     return k;
539   } else {
540     // The only remaining failure mode is NCDFError.
541     // The test here allows for an additional mode CNFException
542     // if callers need to request the reflective error instead.
543     bool throw_error = (failure_mode == NCDFError);
544     k = SystemDictionary::resolve_or_fail(name, class_loader, protection_domain, throw_error, CHECK_NULL);
545   }
546 
547   return k;
548 }
549 
550 oop SignatureStream::as_java_mirror(Handle class_loader, Handle protection_domain,
551                                     FailureMode failure_mode, TRAPS) {
552   if (!is_reference()) {
553     return Universe::java_mirror(type());
554   }
555   Klass* klass = as_klass(class_loader, protection_domain, failure_mode, CHECK_NULL);
556   if (klass == NULL) {
557     return NULL;
558   }
559   return has_Q_descriptor() ? InlineKlass::cast(klass)->val_mirror()
560                             : 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(NULL);
577 }
578 
579 ResolvingSignatureStream::ResolvingSignatureStream(Symbol* signature, Klass* load_origin, bool is_method)
580   : SignatureStream(signature, is_method)
581 {
582   assert(load_origin != NULL, "");
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 ResolvingSignatureStream::ResolvingSignatureStream(fieldDescriptor& field)
593   : SignatureStream(field.signature(), false)
594 {
595   initialize_load_origin(field.field_holder());
596 }
597 
598 void ResolvingSignatureStream::cache_handles() {
599   assert(_load_origin != NULL, "");
600   JavaThread* current = JavaThread::current();
601   _class_loader = Handle(current, _load_origin->class_loader());
602   _protection_domain = Handle(current, _load_origin->protection_domain());
603 }
604 
605 Klass* ResolvingSignatureStream::as_klass_if_loaded(TRAPS) {
606   Klass* klass = as_klass(CachedOrNull, THREAD);
607   // SD::find does not trigger loading, so there should be no throws
608   // Still, bad things can happen, so we CHECK_NULL and ask callers
609   // to do likewise.
610   if (HAS_PENDING_EXCEPTION) {
611     CLEAR_PENDING_EXCEPTION;
612   }
613   return klass;
614 }
615 
616 #ifdef ASSERT
617 extern bool signature_constants_sane(); // called from basic_types_init()
618 
619 bool signature_constants_sane() {
620   // for the lookup table, test every 8-bit code point, and then some:
621   for (int i = -256; i <= 256; i++) {
622     int btcode = 0;
623     switch (i) {
624 #define EACH_SIG(ch, bt, ignore) \
625     case ch: { btcode = bt; break; }
626     SIGNATURE_TYPES_DO(EACH_SIG, ignore)
627 #undef EACH_SIG
628     }
629     int btc = decode_signature_char(i);
630     assert(btc == btcode, "misconfigured table: %d => %d not %d", i, btc, btcode);
631   }
632   return true;
633 }
634 
635 bool SignatureVerifier::is_valid_method_signature(const Symbol* sig) {
636   const char* method_sig = (const char*)sig->bytes();
637   ssize_t len = sig->utf8_length();
638   ssize_t index = 0;
639   if (method_sig != NULL && len > 1 && method_sig[index] == JVM_SIGNATURE_FUNC) {
640     ++index;
641     while (index < len && method_sig[index] != JVM_SIGNATURE_ENDFUNC) {
642       ssize_t res = is_valid_type(&method_sig[index], len - index);
643       if (res == -1) {
644         return false;
645       } else {
646         index += res;
647       }
648     }
649     if (index < len && method_sig[index] == JVM_SIGNATURE_ENDFUNC) {
650       // check the return type
651       ++index;
652       return (is_valid_type(&method_sig[index], len - index) == (len - index));
653     }
654   }
655   return false;
656 }
657 
658 bool SignatureVerifier::is_valid_type_signature(const Symbol* sig) {
659   const char* type_sig = (const char*)sig->bytes();
660   ssize_t len = sig->utf8_length();
661   return (type_sig != NULL && len >= 1 &&
662           (is_valid_type(type_sig, len) == len));
663 }
664 
665 // Checks to see if the type (not to go beyond 'limit') refers to a valid type.
666 // Returns -1 if it is not, or the index of the next character that is not part
667 // of the type.  The type encoding may end before 'limit' and that's ok.
668 ssize_t SignatureVerifier::is_valid_type(const char* type, ssize_t limit) {
669   ssize_t index = 0;
670 
671   // Iterate over any number of array dimensions
672   while (index < limit && type[index] == JVM_SIGNATURE_ARRAY) ++index;
673   if (index >= limit) {
674     return -1;
675   }
676   switch (type[index]) {
677     case JVM_SIGNATURE_BYTE:
678     case JVM_SIGNATURE_CHAR:
679     case JVM_SIGNATURE_FLOAT:
680     case JVM_SIGNATURE_DOUBLE:
681     case JVM_SIGNATURE_INT:
682     case JVM_SIGNATURE_LONG:
683     case JVM_SIGNATURE_SHORT:
684     case JVM_SIGNATURE_BOOLEAN:
685     case JVM_SIGNATURE_VOID:
686       return index + 1;
687     case JVM_SIGNATURE_PRIMITIVE_OBJECT: // fall through
688     case JVM_SIGNATURE_CLASS:
689       for (index = index + 1; index < limit; ++index) {
690         char c = type[index];
691         switch (c) {
692           case JVM_SIGNATURE_ENDCLASS:
693             return index + 1;
694           case '\0': case JVM_SIGNATURE_DOT: case JVM_SIGNATURE_ARRAY:
695             return -1;
696           default: ; // fall through
697         }
698       }
699       // fall through
700     default: ; // fall through
701   }
702   return -1;
703 }
704 
705 #endif // ASSERT
706 
707 // Adds an argument to the signature
708 void SigEntry::add_entry(GrowableArray<SigEntry>* sig, BasicType bt, Symbol* symbol, int offset) {
709   sig->append(SigEntry(bt, offset, symbol));
710   if (bt == T_LONG || bt == T_DOUBLE) {
711     sig->append(SigEntry(T_VOID, offset, symbol)); // Longs and doubles take two stack slots
712   }
713 }
714 
715 // Returns true if the argument at index 'i' is not an inline type delimiter
716 bool SigEntry::skip_value_delimiters(const GrowableArray<SigEntry>* sig, int i) {
717   return (sig->at(i)._bt != T_PRIMITIVE_OBJECT &&
718           (sig->at(i)._bt != T_VOID || sig->at(i-1)._bt == T_LONG || sig->at(i-1)._bt == T_DOUBLE));
719 }
720 
721 // Fill basic type array from signature array
722 int SigEntry::fill_sig_bt(const GrowableArray<SigEntry>* sig, BasicType* sig_bt) {
723   int count = 0;
724   for (int i = 0; i < sig->length(); i++) {
725     if (skip_value_delimiters(sig, i)) {
726       sig_bt[count++] = sig->at(i)._bt;
727     }
728   }
729   return count;
730 }
731 
732 // Create a temporary symbol from the signature array
733 TempNewSymbol SigEntry::create_symbol(const GrowableArray<SigEntry>* sig) {
734   ResourceMark rm;
735   int length = sig->length();
736   char* sig_str = NEW_RESOURCE_ARRAY(char, 2*length + 3);
737   int idx = 0;
738   sig_str[idx++] = '(';
739   for (int i = 0; i < length; i++) {
740     BasicType bt = sig->at(i)._bt;
741     if (bt == T_PRIMITIVE_OBJECT || bt == T_VOID) {
742       // Ignore
743     } else {
744       if (bt == T_ARRAY) {
745         bt = T_OBJECT; // We don't know the element type, treat as Object
746       }
747       sig_str[idx++] = type2char(bt);
748       if (bt == T_OBJECT) {
749         sig_str[idx++] = ';';
750       }
751     }
752   }
753   sig_str[idx++] = ')';
754   // Add a dummy return type. It won't be used but SignatureStream needs it.
755   sig_str[idx++] = 'V';
756   sig_str[idx++] = '\0';
757   return SymbolTable::new_symbol(sig_str);
758 }