1 // verify.cc - verify bytecode
3 /* Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006 Free Software Foundation
5 This file is part of libgcj.
7 This software is copyrighted work licensed under the terms of the
8 Libgcj License. Please consult the file "LIBGCJ_LICENSE" for
11 // Written by Tom Tromey <tromey@redhat.com>
13 // Define VERIFY_DEBUG to enable debugging output.
21 #include <java-insns.h>
22 #include <java-interp.h>
24 // On Solaris 10/x86, <signal.h> indirectly includes <ia32/sys/reg.h>, which
25 // defines PC since g++ predefines __EXTENSIONS__. Undef here to avoid clash
26 // with PC member of class _Jv_BytecodeVerifier below.
31 #include <java/lang/Class.h>
32 #include <java/lang/VerifyError.h>
33 #include <java/lang/Throwable.h>
34 #include <java/lang/reflect/Modifier.h>
35 #include <java/lang/StringBuffer.h>
36 #include <java/lang/NoClassDefFoundError.h>
40 #endif /* VERIFY_DEBUG */
43 // This is used to mark states which are not scheduled for
45 #define INVALID_STATE ((state *) -1)
47 static void debug_print (const char *fmt, ...)
48 __attribute__ ((format (printf, 1, 2)));
51 debug_print (MAYBE_UNUSED const char *fmt, ...)
56 vfprintf (stderr, fmt, ap);
58 #endif /* VERIFY_DEBUG */
61 // This started as a fairly ordinary verifier, and for the most part
62 // it remains so. It works in the obvious way, by modeling the effect
63 // of each opcode as it is encountered. For most opcodes, this is a
64 // straightforward operation.
66 // This verifier does not do type merging. It used to, but this
67 // results in difficulty verifying some relatively simple code
68 // involving interfaces, and it pushed some verification work into the
71 // Instead of merging reference types, when we reach a point where two
72 // flows of control merge, we simply keep the union of reference types
73 // from each branch. Then, when we need to verify a fact about a
74 // reference on the stack (e.g., that it is compatible with the
75 // argument type of a method), we check to ensure that all possible
76 // types satisfy the requirement.
78 // Another area this verifier differs from the norm is in its handling
79 // of subroutines. The JVM specification has some confusing things to
80 // say about subroutines. For instance, it makes claims about not
81 // allowing subroutines to merge and it rejects recursive subroutines.
82 // For the most part these are red herrings; we used to try to follow
83 // these things but they lead to problems. For example, the notion of
84 // "being in a subroutine" is not well-defined: is an exception
85 // handler in a subroutine? If you never execute the `ret' but
86 // instead `goto 1' do you remain in the subroutine?
88 // For clarity on what is really required for type safety, read
89 // "Simple Verification Technique for Complex Java Bytecode
90 // Subroutines" by Alessandro Coglio. Among other things this paper
91 // shows that recursive subroutines are not harmful to type safety.
92 // We implement something similar to what he proposes. Note that this
93 // means that this verifier will accept code that is rejected by some
96 // For those not wanting to read the paper, the basic observation is
97 // that we can maintain split states in subroutines. We maintain one
98 // state for each calling `jsr'. In other words, we re-verify a
99 // subroutine once for each caller, using the exact types held by the
100 // callers (as opposed to the old approach of merging types and
101 // keeping a bitmap registering what did or did not change). This
102 // approach lets us continue to verify correctly even when a
103 // subroutine is exited via `goto' or `athrow' and not `ret'.
105 // In some other areas the JVM specification is (mildly) incorrect,
106 // so we diverge. For instance, you cannot
107 // violate type safety by allocating an object with `new' and then
108 // failing to initialize it, no matter how one branches or where one
109 // stores the uninitialized reference. See "Improving the official
110 // specification of Java bytecode verification" by Alessandro Coglio.
112 // Note that there's no real point in enforcing that padding bytes or
113 // the mystery byte of invokeinterface must be 0, but we do that
116 // The verifier is currently neither completely lazy nor eager when it
117 // comes to loading classes. It tries to represent types by name when
118 // possible, and then loads them when it needs to verify a fact about
119 // the type. Checking types by name is valid because we only use
120 // names which come from the current class' constant pool. Since all
121 // such names are looked up using the same class loader, there is no
122 // danger that we might be fooled into comparing different types with
125 // In the future we plan to allow for a completely lazy mode of
126 // operation, where the verifier will construct a list of type
127 // assertions to be checked later.
129 // Some test cases for the verifier live in the "verify" module of the
130 // Mauve test suite. However, some of these are presently
131 // (2004-01-20) believed to be incorrect. (More precisely the notion
132 // of "correct" is not well-defined, and this verifier differs from
133 // others while remaining type-safe.) Some other tests live in the
134 // libgcj test suite.
135 class _Jv_BytecodeVerifier
139 static const int FLAG_INSN_START = 1;
140 static const int FLAG_BRANCH_TARGET = 2;
145 struct ref_intersection;
156 // The PC corresponding to the start of the current instruction.
159 // The current state of the stack, locals, etc.
160 state *current_state;
162 // At each branch target we keep a linked list of all the states we
163 // can process at that point. We'll only have multiple states at a
164 // given PC if they both have different return-address types in the
165 // same stack or local slot. This array is indexed by PC and holds
166 // the list of all such states.
167 linked<state> **states;
169 // We keep a linked list of all the states which we must reverify.
170 // This is the head of the list.
171 state *next_verify_state;
173 // We keep some flags for each instruction. The values are the
174 // FLAG_* constants defined above. This is an array indexed by PC.
177 // The bytecode itself.
178 unsigned char *bytecode;
180 _Jv_InterpException *exception;
183 jclass current_class;
185 _Jv_InterpMethod *current_method;
187 // A linked list of utf8 objects we allocate.
188 linked<_Jv_Utf8Const> *utf8_list;
190 // A linked list of all ref_intersection objects we allocate.
191 ref_intersection *isect_list;
193 // Create a new Utf-8 constant and return it. We do this to avoid
194 // having our Utf-8 constants prematurely collected.
195 _Jv_Utf8Const *make_utf8_const (char *s, int len)
197 linked<_Jv_Utf8Const> *lu = (linked<_Jv_Utf8Const> *)
198 _Jv_Malloc (sizeof (linked<_Jv_Utf8Const>)
199 + _Jv_Utf8Const::space_needed(s, len));
200 _Jv_Utf8Const *r = (_Jv_Utf8Const *) (lu + 1);
203 lu->next = utf8_list;
209 __attribute__ ((__noreturn__)) void verify_fail (const char *s, jint pc = -1)
211 using namespace java::lang;
212 StringBuffer *buf = new StringBuffer ();
214 buf->append (JvNewStringLatin1 ("verification failed"));
219 buf->append (JvNewStringLatin1 (" at PC "));
223 _Jv_InterpMethod *method = current_method;
224 buf->append (JvNewStringLatin1 (" in "));
225 buf->append (current_class->getName());
226 buf->append ((jchar) ':');
227 buf->append (method->get_method()->name->toString());
228 buf->append ((jchar) '(');
229 buf->append (method->get_method()->signature->toString());
230 buf->append ((jchar) ')');
232 buf->append (JvNewStringLatin1 (": "));
233 buf->append (JvNewStringLatin1 (s));
234 throw new java::lang::VerifyError (buf->toString ());
237 // This enum holds a list of tags for all the different types we
238 // need to handle. Reference types are treated specially by the
244 // The values for primitive types are chosen to correspond to values
245 // specified to newarray.
255 // Used when overwriting second word of a double or long in the
256 // local variables. Also used after merging local variable states
257 // to indicate an unusable value.
260 // This is the second word of a two-word value, i.e., a double or
264 // Everything after `reference_type' must be a reference type.
267 uninitialized_reference_type
270 // This represents a merged class type. Some verifiers (including
271 // earlier versions of this one) will compute the intersection of
272 // two class types when merging states. However, this loses
273 // critical information about interfaces implemented by the various
274 // classes. So instead we keep track of all the actual classes that
276 struct ref_intersection
278 // Whether or not this type has been resolved.
284 // For a resolved reference type, this is a pointer to the class.
286 // For other reference types, this it the name of the class.
290 // Link to the next reference in the intersection.
291 ref_intersection *ref_next;
293 // This is used to keep track of all the allocated
294 // ref_intersection objects, so we can free them.
295 // FIXME: we should allocate these in chunks.
296 ref_intersection *alloc_next;
298 ref_intersection (jclass klass, _Jv_BytecodeVerifier *verifier)
303 alloc_next = verifier->isect_list;
304 verifier->isect_list = this;
307 ref_intersection (_Jv_Utf8Const *name, _Jv_BytecodeVerifier *verifier)
312 alloc_next = verifier->isect_list;
313 verifier->isect_list = this;
316 ref_intersection (ref_intersection *dup, ref_intersection *tail,
317 _Jv_BytecodeVerifier *verifier)
320 is_resolved = dup->is_resolved;
322 alloc_next = verifier->isect_list;
323 verifier->isect_list = this;
326 bool equals (ref_intersection *other, _Jv_BytecodeVerifier *verifier)
328 if (! is_resolved && ! other->is_resolved
329 && _Jv_equalUtf8Classnames (data.name, other->data.name))
333 if (! other->is_resolved)
334 other->resolve (verifier);
335 return data.klass == other->data.klass;
338 // Merge THIS type into OTHER, returning the result. This will
339 // return OTHER if all the classes in THIS already appear in
341 ref_intersection *merge (ref_intersection *other,
342 _Jv_BytecodeVerifier *verifier)
344 ref_intersection *tail = other;
345 for (ref_intersection *self = this; self != NULL; self = self->ref_next)
348 for (ref_intersection *iter = other; iter != NULL;
349 iter = iter->ref_next)
351 if (iter->equals (self, verifier))
359 tail = new ref_intersection (self, tail, verifier);
364 void resolve (_Jv_BytecodeVerifier *verifier)
369 // This is useful if you want to see which classes have to be resolved
370 // while doing the class verification.
371 debug_print("resolving class: %s\n", data.name->chars());
373 using namespace java::lang;
374 java::lang::ClassLoader *loader
375 = verifier->current_class->getClassLoaderInternal();
377 // Due to special handling in to_array() array classes will always
378 // be of the "L ... ;" kind. The separator char ('.' or '/' may vary
380 if (data.name->limit()[-1] == ';')
382 data.klass = _Jv_FindClassFromSignature (data.name->chars(), loader);
383 if (data.klass == NULL)
384 throw new java::lang::NoClassDefFoundError(data.name->toString());
387 data.klass = Class::forName (_Jv_NewStringUtf8Const (data.name),
392 // See if an object of type OTHER can be assigned to an object of
393 // type *THIS. This might resolve classes in one chain or the
395 bool compatible (ref_intersection *other,
396 _Jv_BytecodeVerifier *verifier)
398 ref_intersection *self = this;
400 for (; self != NULL; self = self->ref_next)
402 ref_intersection *other_iter = other;
404 for (; other_iter != NULL; other_iter = other_iter->ref_next)
406 // Avoid resolving if possible.
407 if (! self->is_resolved
408 && ! other_iter->is_resolved
409 && _Jv_equalUtf8Classnames (self->data.name,
410 other_iter->data.name))
413 if (! self->is_resolved)
414 self->resolve(verifier);
416 // If the LHS of the expression is of type
417 // java.lang.Object, assignment will succeed, no matter
418 // what the type of the RHS is. Using this short-cut we
419 // don't need to resolve the class of the RHS at
420 // verification time.
421 if (self->data.klass == &java::lang::Object::class$)
424 if (! other_iter->is_resolved)
425 other_iter->resolve(verifier);
427 if (! is_assignable_from_slow (self->data.klass,
428 other_iter->data.klass))
438 // assert (ref_next == NULL);
440 return data.klass->isArray ();
442 return data.name->first() == '[';
445 bool isinterface (_Jv_BytecodeVerifier *verifier)
447 // assert (ref_next == NULL);
450 return data.klass->isInterface ();
453 bool isabstract (_Jv_BytecodeVerifier *verifier)
455 // assert (ref_next == NULL);
458 using namespace java::lang::reflect;
459 return Modifier::isAbstract (data.klass->getModifiers ());
462 jclass getclass (_Jv_BytecodeVerifier *verifier)
469 int count_dimensions ()
474 jclass k = data.klass;
475 while (k->isArray ())
477 k = k->getComponentType ();
483 char *p = data.name->chars();
490 void *operator new (size_t bytes)
492 return _Jv_Malloc (bytes);
495 void operator delete (void *mem)
501 // Return the type_val corresponding to a primitive signature
502 // character. For instance `I' returns `int.class'.
503 type_val get_type_val_for_signature (jchar sig)
536 verify_fail ("invalid signature");
541 // Return the type_val corresponding to a primitive class.
542 type_val get_type_val_for_signature (jclass k)
544 return get_type_val_for_signature ((jchar) k->method_count);
547 // This is like _Jv_IsAssignableFrom, but it works even if SOURCE or
548 // TARGET haven't been prepared.
549 static bool is_assignable_from_slow (jclass target, jclass source)
551 // First, strip arrays.
552 while (target->isArray ())
554 // If target is array, source must be as well.
555 if (! source->isArray ())
557 target = target->getComponentType ();
558 source = source->getComponentType ();
562 if (target == &java::lang::Object::class$)
567 if (source == target)
570 if (target->isPrimitive () || source->isPrimitive ())
573 if (target->isInterface ())
575 for (int i = 0; i < source->interface_count; ++i)
577 // We use a recursive call because we also need to
578 // check superinterfaces.
579 if (is_assignable_from_slow (target, source->getInterface (i)))
583 source = source->getSuperclass ();
585 while (source != NULL);
590 // The `type' class is used to represent a single type in the
597 // For reference types, the representation of the type.
598 ref_intersection *klass;
600 // This is used in two situations.
602 // First, when constructing a new object, it is the PC of the
603 // `new' instruction which created the object. We use the special
604 // value UNINIT to mean that this is uninitialized. The special
605 // value SELF is used for the case where the current method is
606 // itself the <init> method. the special value EITHER is used
607 // when we may optionally allow either an uninitialized or
608 // initialized reference to match.
610 // Second, when the key is return_address_type, this holds the PC
611 // of the instruction following the `jsr'.
614 static const int UNINIT = -2;
615 static const int SELF = -1;
616 static const int EITHER = -3;
618 // Basic constructor.
621 key = unsuitable_type;
626 // Make a new instance given the type tag. We assume a generic
627 // `reference_type' means Object.
631 // For reference_type, if KLASS==NULL then that means we are
632 // looking for a generic object of any kind, including an
633 // uninitialized reference.
638 // Make a new instance given a class.
639 type (jclass k, _Jv_BytecodeVerifier *verifier)
641 key = reference_type;
642 klass = new ref_intersection (k, verifier);
646 // Make a new instance given the name of a class.
647 type (_Jv_Utf8Const *n, _Jv_BytecodeVerifier *verifier)
649 key = reference_type;
650 klass = new ref_intersection (n, verifier);
662 // These operators are required because libgcj can't link in
664 void *operator new[] (size_t bytes)
666 return _Jv_Malloc (bytes);
669 void operator delete[] (void *mem)
674 type& operator= (type_val k)
682 type& operator= (const type& t)
690 // Promote a numeric type.
693 if (key == boolean_type || key == char_type
694 || key == byte_type || key == short_type)
699 // Mark this type as the uninitialized result of `new'.
700 void set_uninitialized (int npc, _Jv_BytecodeVerifier *verifier)
702 if (key == reference_type)
703 key = uninitialized_reference_type;
705 verifier->verify_fail ("internal error in type::uninitialized");
709 // Mark this type as now initialized.
710 void set_initialized (int npc)
712 if (npc != UNINIT && pc == npc && key == uninitialized_reference_type)
714 key = reference_type;
719 // Mark this type as a particular return address.
720 void set_return_address (int npc)
725 // Return true if this type and type OTHER are considered
726 // mergeable for the purposes of state merging. This is related
727 // to subroutine handling. For this purpose two types are
728 // considered unmergeable if they are both return-addresses but
729 // have different PCs.
730 bool state_mergeable_p (const type &other) const
732 return (key != return_address_type
733 || other.key != return_address_type
737 // Return true if an object of type K can be assigned to a variable
738 // of type *THIS. Handle various special cases too. Might modify
739 // *THIS or K. Note however that this does not perform numeric
741 bool compatible (type &k, _Jv_BytecodeVerifier *verifier)
743 // Any type is compatible with the unsuitable type.
744 if (key == unsuitable_type)
747 if (key < reference_type || k.key < reference_type)
750 // The `null' type is convertible to any initialized reference
752 if (key == null_type)
753 return k.key != uninitialized_reference_type;
754 if (k.key == null_type)
755 return key != uninitialized_reference_type;
757 // A special case for a generic reference.
761 verifier->verify_fail ("programmer error in type::compatible");
763 // Handle the special 'EITHER' case, which is only used in a
764 // special case of 'putfield'. Note that we only need to handle
765 // this on the LHS of a check.
766 if (! isinitialized () && pc == EITHER)
768 // If the RHS is uninitialized, it must be an uninitialized
770 if (! k.isinitialized () && k.pc != SELF)
773 else if (isinitialized () != k.isinitialized ())
775 // An initialized type and an uninitialized type are not
776 // otherwise compatible.
781 // Two uninitialized objects are compatible if either:
782 // * The PCs are identical, or
783 // * One PC is UNINIT.
784 if (! isinitialized ())
786 if (pc != k.pc && pc != UNINIT && k.pc != UNINIT)
791 return klass->compatible(k.klass, verifier);
794 bool equals (const type &other, _Jv_BytecodeVerifier *vfy)
796 // Only works for reference types.
797 if ((key != reference_type
798 && key != uninitialized_reference_type)
799 || (other.key != reference_type
800 && other.key != uninitialized_reference_type))
802 // Only for single-valued types.
803 if (klass->ref_next || other.klass->ref_next)
805 return klass->equals (other.klass, vfy);
810 return key == void_type;
815 return key == long_type || key == double_type;
818 // Return number of stack or local variable slots taken by this
822 return iswide () ? 2 : 1;
825 bool isarray () const
827 // We treat null_type as not an array. This is ok based on the
828 // current uses of this method.
829 if (key == reference_type)
830 return klass->isarray ();
836 return key == null_type;
839 bool isinterface (_Jv_BytecodeVerifier *verifier)
841 if (key != reference_type)
843 return klass->isinterface (verifier);
846 bool isabstract (_Jv_BytecodeVerifier *verifier)
848 if (key != reference_type)
850 return klass->isabstract (verifier);
853 // Return the element type of an array.
854 type element_type (_Jv_BytecodeVerifier *verifier)
856 if (key != reference_type)
857 verifier->verify_fail ("programmer error in type::element_type()", -1);
859 jclass k = klass->getclass (verifier)->getComponentType ();
860 if (k->isPrimitive ())
861 return type (verifier->get_type_val_for_signature (k));
862 return type (k, verifier);
865 // Return the array type corresponding to an initialized
866 // reference. We could expand this to work for other kinds of
867 // types, but currently we don't need to.
868 type to_array (_Jv_BytecodeVerifier *verifier)
870 if (key != reference_type)
871 verifier->verify_fail ("internal error in type::to_array()");
873 // In case the class is already resolved we can simply ask the runtime
874 // to give us the array version.
875 // If it is not resolved we prepend "[" to the classname to make the
876 // array usage verification more lazy. In other words: makes new Foo[300]
877 // pass the verifier if Foo.class is missing.
878 if (klass->is_resolved)
880 jclass k = klass->getclass (verifier);
882 return type (_Jv_GetArrayClass (k, k->getClassLoaderInternal()),
887 int len = klass->data.name->len();
889 // If the classname is given in the Lp1/p2/cn; format we only need
890 // to add a leading '['. The same procedure has to be done for
891 // primitive arrays (ie. provided "[I", the result should be "[[I".
892 // If the classname is given as p1.p2.cn we have to embed it into
894 if (klass->data.name->limit()[-1] == ';' ||
895 _Jv_isPrimitiveOrDerived(klass->data.name))
897 // Reserves space for leading '[' and trailing '\0' .
898 char arrayName[len + 2];
901 strcpy(&arrayName[1], klass->data.name->chars());
904 // This is only needed when we want to print the string to the
905 // screen while debugging.
906 arrayName[len + 1] = '\0';
908 debug_print("len: %d - old: '%s' - new: '%s'\n", len, klass->data.name->chars(), arrayName);
911 return type (verifier->make_utf8_const( arrayName, len + 1 ),
916 // Reserves space for leading "[L" and trailing ';' and '\0' .
917 char arrayName[len + 4];
921 strcpy(&arrayName[2], klass->data.name->chars());
922 arrayName[len + 2] = ';';
925 // This is only needed when we want to print the string to the
926 // screen while debugging.
927 arrayName[len + 3] = '\0';
929 debug_print("len: %d - old: '%s' - new: '%s'\n", len, klass->data.name->chars(), arrayName);
932 return type (verifier->make_utf8_const( arrayName, len + 3 ),
939 bool isreference () const
941 return key >= reference_type;
949 bool isinitialized () const
951 return key == reference_type || key == null_type;
954 bool isresolved () const
956 return (key == reference_type
958 || key == uninitialized_reference_type);
961 void verify_dimensions (int ndims, _Jv_BytecodeVerifier *verifier)
963 // The way this is written, we don't need to check isarray().
964 if (key != reference_type)
965 verifier->verify_fail ("internal error in verify_dimensions:"
966 " not a reference type");
968 if (klass->count_dimensions () < ndims)
969 verifier->verify_fail ("array type has fewer dimensions"
973 // Merge OLD_TYPE into this. On error throw exception. Return
974 // true if the merge caused a type change.
975 bool merge (type& old_type, bool local_semantics,
976 _Jv_BytecodeVerifier *verifier)
978 bool changed = false;
979 bool refo = old_type.isreference ();
980 bool refn = isreference ();
983 if (old_type.key == null_type)
985 else if (key == null_type)
990 else if (isinitialized () != old_type.isinitialized ())
991 verifier->verify_fail ("merging initialized and uninitialized types");
994 if (! isinitialized ())
998 else if (old_type.pc == UNINIT)
1000 else if (pc != old_type.pc)
1001 verifier->verify_fail ("merging different uninitialized types");
1004 ref_intersection *merged = old_type.klass->merge (klass,
1006 if (merged != klass)
1013 else if (refo || refn || key != old_type.key)
1015 if (local_semantics)
1017 // If we already have an `unsuitable' type, then we
1018 // don't need to change again.
1019 if (key != unsuitable_type)
1021 key = unsuitable_type;
1026 verifier->verify_fail ("unmergeable type");
1032 void print (void) const
1037 case boolean_type: c = 'Z'; break;
1038 case byte_type: c = 'B'; break;
1039 case char_type: c = 'C'; break;
1040 case short_type: c = 'S'; break;
1041 case int_type: c = 'I'; break;
1042 case long_type: c = 'J'; break;
1043 case float_type: c = 'F'; break;
1044 case double_type: c = 'D'; break;
1045 case void_type: c = 'V'; break;
1046 case unsuitable_type: c = '-'; break;
1047 case return_address_type: c = 'r'; break;
1048 case continuation_type: c = '+'; break;
1049 case reference_type: c = 'L'; break;
1050 case null_type: c = '@'; break;
1051 case uninitialized_reference_type: c = 'U'; break;
1053 debug_print ("%c", c);
1055 #endif /* VERIFY_DEBUG */
1058 // This class holds all the state information we need for a given
1062 // The current top of the stack, in terms of slots.
1064 // The current depth of the stack. This will be larger than
1065 // STACKTOP when wide types are on the stack.
1069 // The local variables.
1071 // We keep track of the type of `this' specially. This is used to
1072 // ensure that an instance initializer invokes another initializer
1073 // on `this' before returning. We must keep track of this
1074 // specially because otherwise we might be confused by code which
1075 // assigns to locals[0] (overwriting `this') and then returns
1076 // without really initializing.
1079 // The PC for this state. This is only valid on states which are
1080 // permanently attached to a given PC. For an object like
1081 // `current_state', which is used transiently, this has no
1084 // We keep a linked list of all states requiring reverification.
1085 // If this is the special value INVALID_STATE then this state is
1086 // not on the list. NULL marks the end of the linked list.
1089 // NO_NEXT is the PC value meaning that a new state must be
1090 // acquired from the verification list.
1091 static const int NO_NEXT = -1;
1098 next = INVALID_STATE;
1101 state (int max_stack, int max_locals)
1106 stack = new type[max_stack];
1107 for (int i = 0; i < max_stack; ++i)
1108 stack[i] = unsuitable_type;
1109 locals = new type[max_locals];
1110 for (int i = 0; i < max_locals; ++i)
1111 locals[i] = unsuitable_type;
1113 next = INVALID_STATE;
1116 state (const state *orig, int max_stack, int max_locals)
1118 stack = new type[max_stack];
1119 locals = new type[max_locals];
1120 copy (orig, max_stack, max_locals);
1122 next = INVALID_STATE;
1133 void *operator new[] (size_t bytes)
1135 return _Jv_Malloc (bytes);
1138 void operator delete[] (void *mem)
1143 void *operator new (size_t bytes)
1145 return _Jv_Malloc (bytes);
1148 void operator delete (void *mem)
1153 void copy (const state *copy, int max_stack, int max_locals)
1155 stacktop = copy->stacktop;
1156 stackdepth = copy->stackdepth;
1157 for (int i = 0; i < max_stack; ++i)
1158 stack[i] = copy->stack[i];
1159 for (int i = 0; i < max_locals; ++i)
1160 locals[i] = copy->locals[i];
1162 this_type = copy->this_type;
1163 // Don't modify `next' or `pc'.
1166 // Modify this state to reflect entry to an exception handler.
1167 void set_exception (type t, int max_stack)
1172 for (int i = stacktop; i < max_stack; ++i)
1173 stack[i] = unsuitable_type;
1176 inline int get_pc () const
1181 void set_pc (int npc)
1186 // Merge STATE_OLD into this state. Destructively modifies this
1187 // state. Returns true if the new state was in fact changed.
1188 // Will throw an exception if the states are not mergeable.
1189 bool merge (state *state_old, int max_locals,
1190 _Jv_BytecodeVerifier *verifier)
1192 bool changed = false;
1194 // Special handling for `this'. If one or the other is
1195 // uninitialized, then the merge is uninitialized.
1196 if (this_type.isinitialized ())
1197 this_type = state_old->this_type;
1200 if (state_old->stacktop != stacktop) // FIXME stackdepth instead?
1201 verifier->verify_fail ("stack sizes differ");
1202 for (int i = 0; i < state_old->stacktop; ++i)
1204 if (stack[i].merge (state_old->stack[i], false, verifier))
1208 // Merge local variables.
1209 for (int i = 0; i < max_locals; ++i)
1211 if (locals[i].merge (state_old->locals[i], true, verifier))
1218 // Ensure that `this' has been initialized.
1219 void check_this_initialized (_Jv_BytecodeVerifier *verifier)
1221 if (this_type.isreference () && ! this_type.isinitialized ())
1222 verifier->verify_fail ("`this' is uninitialized");
1225 // Set type of `this'.
1226 void set_this_type (const type &k)
1231 // Mark each `new'd object we know of that was allocated at PC as
1233 void set_initialized (int pc, int max_locals)
1235 for (int i = 0; i < stacktop; ++i)
1236 stack[i].set_initialized (pc);
1237 for (int i = 0; i < max_locals; ++i)
1238 locals[i].set_initialized (pc);
1239 this_type.set_initialized (pc);
1242 // This tests to see whether two states can be considered "merge
1243 // compatible". If both states have a return-address in the same
1244 // slot, and the return addresses are different, then they are not
1245 // compatible and we must not try to merge them.
1246 bool state_mergeable_p (state *other, int max_locals,
1247 _Jv_BytecodeVerifier *verifier)
1249 // This is tricky: if the stack sizes differ, then not only are
1250 // these not mergeable, but in fact we should give an error, as
1251 // we've found two execution paths that reach a branch target
1252 // with different stack depths. FIXME stackdepth instead?
1253 if (stacktop != other->stacktop)
1254 verifier->verify_fail ("stack sizes differ");
1256 for (int i = 0; i < stacktop; ++i)
1257 if (! stack[i].state_mergeable_p (other->stack[i]))
1259 for (int i = 0; i < max_locals; ++i)
1260 if (! locals[i].state_mergeable_p (other->locals[i]))
1265 void reverify (_Jv_BytecodeVerifier *verifier)
1267 if (next == INVALID_STATE)
1269 next = verifier->next_verify_state;
1270 verifier->next_verify_state = this;
1275 void print (const char *leader, int pc,
1276 int max_stack, int max_locals) const
1278 debug_print ("%s [%4d]: [stack] ", leader, pc);
1280 for (i = 0; i < stacktop; ++i)
1282 for (; i < max_stack; ++i)
1284 debug_print (" [local] ");
1285 for (i = 0; i < max_locals; ++i)
1287 debug_print (" | %p\n", this);
1290 inline void print (const char *, int, int, int) const
1293 #endif /* VERIFY_DEBUG */
1298 if (current_state->stacktop <= 0)
1299 verify_fail ("stack empty");
1300 type r = current_state->stack[--current_state->stacktop];
1301 current_state->stackdepth -= r.depth ();
1302 if (current_state->stackdepth < 0)
1303 verify_fail ("stack empty", start_PC);
1309 type r = pop_raw ();
1311 verify_fail ("narrow pop of wide type");
1315 type pop_type (type match)
1318 type t = pop_raw ();
1319 if (! match.compatible (t, this))
1320 verify_fail ("incompatible type on stack");
1324 // Pop a reference which is guaranteed to be initialized. MATCH
1325 // doesn't have to be a reference type; in this case this acts like
1327 type pop_init_ref (type match)
1329 type t = pop_raw ();
1330 if (t.isreference () && ! t.isinitialized ())
1331 verify_fail ("initialized reference required");
1332 else if (! match.compatible (t, this))
1333 verify_fail ("incompatible type on stack");
1337 // Pop a reference type or a return address.
1338 type pop_ref_or_return ()
1340 type t = pop_raw ();
1341 if (! t.isreference () && t.key != return_address_type)
1342 verify_fail ("expected reference or return address on stack");
1346 void push_type (type t)
1348 // If T is a numeric type like short, promote it to int.
1351 int depth = t.depth ();
1352 if (current_state->stackdepth + depth > current_method->max_stack)
1353 verify_fail ("stack overflow");
1354 current_state->stack[current_state->stacktop++] = t;
1355 current_state->stackdepth += depth;
1358 void set_variable (int index, type t)
1360 // If T is a numeric type like short, promote it to int.
1363 int depth = t.depth ();
1364 if (index > current_method->max_locals - depth)
1365 verify_fail ("invalid local variable");
1366 current_state->locals[index] = t;
1369 current_state->locals[index + 1] = continuation_type;
1370 if (index > 0 && current_state->locals[index - 1].iswide ())
1371 current_state->locals[index - 1] = unsuitable_type;
1374 type get_variable (int index, type t)
1376 int depth = t.depth ();
1377 if (index > current_method->max_locals - depth)
1378 verify_fail ("invalid local variable");
1379 if (! t.compatible (current_state->locals[index], this))
1380 verify_fail ("incompatible type in local variable");
1383 type t (continuation_type);
1384 if (! current_state->locals[index + 1].compatible (t, this))
1385 verify_fail ("invalid local variable");
1387 return current_state->locals[index];
1390 // Make sure ARRAY is an array type and that its elements are
1391 // compatible with type ELEMENT. Returns the actual element type.
1392 type require_array_type (type array, type element)
1394 // An odd case. Here we just pretend that everything went ok. If
1395 // the requested element type is some kind of reference, return
1396 // the null type instead.
1397 if (array.isnull ())
1398 return element.isreference () ? type (null_type) : element;
1400 if (! array.isarray ())
1401 verify_fail ("array required");
1403 type t = array.element_type (this);
1404 if (! element.compatible (t, this))
1406 // Special case for byte arrays, which must also be boolean
1409 if (element.key == byte_type)
1411 type e2 (boolean_type);
1412 ok = e2.compatible (t, this);
1415 verify_fail ("incompatible array element type");
1418 // Return T and not ELEMENT, because T might be specialized.
1424 if (PC >= current_method->code_length)
1425 verify_fail ("premature end of bytecode");
1426 return (jint) bytecode[PC++] & 0xff;
1431 jint b1 = get_byte ();
1432 jint b2 = get_byte ();
1433 return (jint) ((b1 << 8) | b2) & 0xffff;
1438 jint b1 = get_byte ();
1439 jint b2 = get_byte ();
1440 jshort s = (b1 << 8) | b2;
1446 jint b1 = get_byte ();
1447 jint b2 = get_byte ();
1448 jint b3 = get_byte ();
1449 jint b4 = get_byte ();
1450 return (b1 << 24) | (b2 << 16) | (b3 << 8) | b4;
1453 int compute_jump (int offset)
1455 int npc = start_PC + offset;
1456 if (npc < 0 || npc >= current_method->code_length)
1457 verify_fail ("branch out of range", start_PC);
1461 // Add a new state to the state list at NPC.
1462 state *add_new_state (int npc, state *old_state)
1464 state *new_state = new state (old_state, current_method->max_stack,
1465 current_method->max_locals);
1466 debug_print ("== New state in add_new_state\n");
1467 new_state->print ("New", npc, current_method->max_stack,
1468 current_method->max_locals);
1469 linked<state> *nlink
1470 = (linked<state> *) _Jv_Malloc (sizeof (linked<state>));
1471 nlink->val = new_state;
1472 nlink->next = states[npc];
1473 states[npc] = nlink;
1474 new_state->set_pc (npc);
1478 // Merge the indicated state into the state at the branch target and
1479 // schedule a new PC if there is a change. NPC is the PC of the
1480 // branch target, and FROM_STATE is the state at the source of the
1481 // branch. This method returns true if the destination state
1482 // changed and requires reverification, false otherwise.
1483 void merge_into (int npc, state *from_state)
1485 // Iterate over all target states and merge our state into each,
1486 // if applicable. FIXME one improvement we could make here is
1487 // "state destruction". Merging a new state into an existing one
1488 // might cause a return_address_type to be merged to
1489 // unsuitable_type. In this case the resulting state may now be
1490 // mergeable with other states currently held in parallel at this
1491 // location. So in this situation we could pairwise compare and
1492 // reduce the number of parallel states.
1493 bool applicable = false;
1494 for (linked<state> *iter = states[npc]; iter != NULL; iter = iter->next)
1496 state *new_state = iter->val;
1497 if (new_state->state_mergeable_p (from_state,
1498 current_method->max_locals, this))
1502 debug_print ("== Merge states in merge_into\n");
1503 from_state->print ("Frm", start_PC, current_method->max_stack,
1504 current_method->max_locals);
1505 new_state->print (" To", npc, current_method->max_stack,
1506 current_method->max_locals);
1507 bool changed = new_state->merge (from_state,
1508 current_method->max_locals,
1510 new_state->print ("New", npc, current_method->max_stack,
1511 current_method->max_locals);
1514 new_state->reverify (this);
1520 // Either we don't yet have a state at NPC, or we have a
1521 // return-address type that is in conflict with all existing
1522 // state. So, we need to create a new entry.
1523 state *new_state = add_new_state (npc, from_state);
1524 // A new state added in this way must always be reverified.
1525 new_state->reverify (this);
1529 void push_jump (int offset)
1531 int npc = compute_jump (offset);
1532 // According to the JVM Spec, we need to check for uninitialized
1533 // objects here. However, this does not actually affect type
1534 // safety, and the Eclipse java compiler generates code that
1535 // violates this constraint.
1536 merge_into (npc, current_state);
1539 void push_exception_jump (type t, int pc)
1541 // According to the JVM Spec, we need to check for uninitialized
1542 // objects here. However, this does not actually affect type
1543 // safety, and the Eclipse java compiler generates code that
1544 // violates this constraint.
1545 state s (current_state, current_method->max_stack,
1546 current_method->max_locals);
1547 if (current_method->max_stack < 1)
1548 verify_fail ("stack overflow at exception handler");
1549 s.set_exception (t, current_method->max_stack);
1550 merge_into (pc, &s);
1555 state *new_state = next_verify_state;
1556 if (new_state == INVALID_STATE)
1557 verify_fail ("programmer error in pop_jump");
1558 if (new_state != NULL)
1560 next_verify_state = new_state->next;
1561 new_state->next = INVALID_STATE;
1566 void invalidate_pc ()
1568 PC = state::NO_NEXT;
1571 void note_branch_target (int pc)
1573 // Don't check `pc <= PC', because we've advanced PC after
1574 // fetching the target and we haven't yet checked the next
1576 if (pc < PC && ! (flags[pc] & FLAG_INSN_START))
1577 verify_fail ("branch not to instruction start", start_PC);
1578 flags[pc] |= FLAG_BRANCH_TARGET;
1581 void skip_padding ()
1583 while ((PC % 4) > 0)
1584 if (get_byte () != 0)
1585 verify_fail ("found nonzero padding byte");
1588 // Do the work for a `ret' instruction. INDEX is the index into the
1590 void handle_ret_insn (int index)
1592 type ret_addr = get_variable (index, return_address_type);
1593 // It would be nice if we could do this. However, the JVM Spec
1594 // doesn't say that this is what happens. It is implied that
1595 // reusing a return address is invalid, but there's no actual
1596 // prohibition against it.
1597 // set_variable (index, unsuitable_type);
1599 int npc = ret_addr.get_pc ();
1600 // We might be returning to a `jsr' that is at the end of the
1601 // bytecode. This is ok if we never return from the called
1602 // subroutine, but if we see this here it is an error.
1603 if (npc >= current_method->code_length)
1604 verify_fail ("fell off end");
1606 // According to the JVM Spec, we need to check for uninitialized
1607 // objects here. However, this does not actually affect type
1608 // safety, and the Eclipse java compiler generates code that
1609 // violates this constraint.
1610 merge_into (npc, current_state);
1614 void handle_jsr_insn (int offset)
1616 int npc = compute_jump (offset);
1618 // According to the JVM Spec, we need to check for uninitialized
1619 // objects here. However, this does not actually affect type
1620 // safety, and the Eclipse java compiler generates code that
1621 // violates this constraint.
1623 // Modify our state as appropriate for entry into a subroutine.
1624 type ret_addr (return_address_type);
1625 ret_addr.set_return_address (PC);
1626 push_type (ret_addr);
1627 merge_into (npc, current_state);
1631 jclass construct_primitive_array_type (type_val prim)
1637 k = JvPrimClass (boolean);
1640 k = JvPrimClass (char);
1643 k = JvPrimClass (float);
1646 k = JvPrimClass (double);
1649 k = JvPrimClass (byte);
1652 k = JvPrimClass (short);
1655 k = JvPrimClass (int);
1658 k = JvPrimClass (long);
1661 // These aren't used here but we call them out to avoid
1664 case unsuitable_type:
1665 case return_address_type:
1666 case continuation_type:
1667 case reference_type:
1669 case uninitialized_reference_type:
1671 verify_fail ("unknown type in construct_primitive_array_type");
1673 k = _Jv_GetArrayClass (k, NULL);
1677 // This pass computes the location of branch targets and also
1678 // instruction starts.
1679 void branch_prepass ()
1681 flags = (char *) _Jv_Malloc (current_method->code_length);
1683 for (int i = 0; i < current_method->code_length; ++i)
1687 while (PC < current_method->code_length)
1689 // Set `start_PC' early so that error checking can have the
1692 flags[PC] |= FLAG_INSN_START;
1694 java_opcode opcode = (java_opcode) bytecode[PC++];
1698 case op_aconst_null:
1834 case op_monitorenter:
1835 case op_monitorexit:
1843 case op_arraylength:
1875 case op_invokespecial:
1876 case op_invokestatic:
1877 case op_invokevirtual:
1881 case op_multianewarray:
1904 note_branch_target (compute_jump (get_short ()));
1907 case op_tableswitch:
1910 note_branch_target (compute_jump (get_int ()));
1911 jint low = get_int ();
1912 jint hi = get_int ();
1914 verify_fail ("invalid tableswitch", start_PC);
1915 for (int i = low; i <= hi; ++i)
1916 note_branch_target (compute_jump (get_int ()));
1920 case op_lookupswitch:
1923 note_branch_target (compute_jump (get_int ()));
1924 int npairs = get_int ();
1926 verify_fail ("too few pairs in lookupswitch", start_PC);
1927 while (npairs-- > 0)
1930 note_branch_target (compute_jump (get_int ()));
1935 case op_invokeinterface:
1943 opcode = (java_opcode) get_byte ();
1945 if (opcode == op_iinc)
1952 note_branch_target (compute_jump (get_int ()));
1955 // These are unused here, but we call them out explicitly
1956 // so that -Wswitch-enum doesn't complain.
1962 case op_putstatic_1:
1963 case op_putstatic_2:
1964 case op_putstatic_4:
1965 case op_putstatic_8:
1966 case op_putstatic_a:
1968 case op_getfield_2s:
1969 case op_getfield_2u:
1973 case op_getstatic_1:
1974 case op_getstatic_2s:
1975 case op_getstatic_2u:
1976 case op_getstatic_4:
1977 case op_getstatic_8:
1978 case op_getstatic_a:
1981 verify_fail ("unrecognized instruction in branch_prepass",
1985 // See if any previous branch tried to branch to the middle of
1986 // this instruction.
1987 for (int pc = start_PC + 1; pc < PC; ++pc)
1989 if ((flags[pc] & FLAG_BRANCH_TARGET))
1990 verify_fail ("branch to middle of instruction", pc);
1994 // Verify exception handlers.
1995 for (int i = 0; i < current_method->exc_count; ++i)
1997 if (! (flags[exception[i].handler_pc.i] & FLAG_INSN_START))
1998 verify_fail ("exception handler not at instruction start",
1999 exception[i].handler_pc.i);
2000 if (! (flags[exception[i].start_pc.i] & FLAG_INSN_START))
2001 verify_fail ("exception start not at instruction start",
2002 exception[i].start_pc.i);
2003 if (exception[i].end_pc.i != current_method->code_length
2004 && ! (flags[exception[i].end_pc.i] & FLAG_INSN_START))
2005 verify_fail ("exception end not at instruction start",
2006 exception[i].end_pc.i);
2008 flags[exception[i].handler_pc.i] |= FLAG_BRANCH_TARGET;
2012 void check_pool_index (int index)
2014 if (index < 0 || index >= current_class->constants.size)
2015 verify_fail ("constant pool index out of range", start_PC);
2018 type check_class_constant (int index)
2020 check_pool_index (index);
2021 _Jv_Constants *pool = ¤t_class->constants;
2022 if (pool->tags[index] == JV_CONSTANT_ResolvedClass)
2023 return type (pool->data[index].clazz, this);
2024 else if (pool->tags[index] == JV_CONSTANT_Class)
2025 return type (pool->data[index].utf8, this);
2026 verify_fail ("expected class constant", start_PC);
2029 type check_constant (int index)
2031 check_pool_index (index);
2032 _Jv_Constants *pool = ¤t_class->constants;
2033 int tag = pool->tags[index];
2034 if (tag == JV_CONSTANT_ResolvedString || tag == JV_CONSTANT_String)
2035 return type (&java::lang::String::class$, this);
2036 else if (tag == JV_CONSTANT_Integer)
2037 return type (int_type);
2038 else if (tag == JV_CONSTANT_Float)
2039 return type (float_type);
2040 else if (current_method->is_15
2041 && (tag == JV_CONSTANT_ResolvedClass || tag == JV_CONSTANT_Class))
2042 return type (&java::lang::Class::class$, this);
2043 verify_fail ("String, int, or float constant expected", start_PC);
2046 type check_wide_constant (int index)
2048 check_pool_index (index);
2049 _Jv_Constants *pool = ¤t_class->constants;
2050 if (pool->tags[index] == JV_CONSTANT_Long)
2051 return type (long_type);
2052 else if (pool->tags[index] == JV_CONSTANT_Double)
2053 return type (double_type);
2054 verify_fail ("long or double constant expected", start_PC);
2057 // Helper for both field and method. These are laid out the same in
2058 // the constant pool.
2059 type handle_field_or_method (int index, int expected,
2060 _Jv_Utf8Const **name,
2061 _Jv_Utf8Const **fmtype)
2063 check_pool_index (index);
2064 _Jv_Constants *pool = ¤t_class->constants;
2065 if (pool->tags[index] != expected)
2066 verify_fail ("didn't see expected constant", start_PC);
2067 // Once we know we have a Fieldref or Methodref we assume that it
2068 // is correctly laid out in the constant pool. I think the code
2069 // in defineclass.cc guarantees this.
2070 _Jv_ushort class_index, name_and_type_index;
2071 _Jv_loadIndexes (&pool->data[index],
2073 name_and_type_index);
2074 _Jv_ushort name_index, desc_index;
2075 _Jv_loadIndexes (&pool->data[name_and_type_index],
2076 name_index, desc_index);
2078 *name = pool->data[name_index].utf8;
2079 *fmtype = pool->data[desc_index].utf8;
2081 return check_class_constant (class_index);
2084 // Return field's type, compute class' type if requested.
2085 // If PUTFIELD is true, use the special 'putfield' semantics.
2086 type check_field_constant (int index, type *class_type = NULL,
2087 bool putfield = false)
2089 _Jv_Utf8Const *name, *field_type;
2090 type ct = handle_field_or_method (index,
2091 JV_CONSTANT_Fieldref,
2092 &name, &field_type);
2096 if (field_type->first() == '[' || field_type->first() == 'L')
2097 result = type (field_type, this);
2099 result = get_type_val_for_signature (field_type->first());
2101 // We have an obscure special case here: we can use `putfield' on
2102 // a field declared in this class, even if `this' has not yet been
2105 && ! current_state->this_type.isinitialized ()
2106 && current_state->this_type.pc == type::SELF
2107 && current_state->this_type.equals (ct, this)
2108 // We don't look at the signature, figuring that if it is
2109 // wrong we will fail during linking. FIXME?
2110 && _Jv_Linker::has_field_p (current_class, name))
2111 // Note that we don't actually know whether we're going to match
2112 // against 'this' or some other object of the same type. So,
2113 // here we set things up so that it doesn't matter. This relies
2114 // on knowing what our caller is up to.
2115 class_type->set_uninitialized (type::EITHER, this);
2120 type check_method_constant (int index, bool is_interface,
2121 _Jv_Utf8Const **method_name,
2122 _Jv_Utf8Const **method_signature)
2124 return handle_field_or_method (index,
2126 ? JV_CONSTANT_InterfaceMethodref
2127 : JV_CONSTANT_Methodref),
2128 method_name, method_signature);
2131 type get_one_type (char *&p)
2149 _Jv_Utf8Const *name = make_utf8_const (start, p - start);
2150 return type (name, this);
2153 // Casting to jchar here is ok since we are looking at an ASCII
2155 type_val rt = get_type_val_for_signature (jchar (v));
2157 if (arraycount == 0)
2159 // Callers of this function eventually push their arguments on
2160 // the stack. So, promote them here.
2161 return type (rt).promote ();
2164 jclass k = construct_primitive_array_type (rt);
2165 while (--arraycount > 0)
2166 k = _Jv_GetArrayClass (k, NULL);
2167 return type (k, this);
2170 void compute_argument_types (_Jv_Utf8Const *signature,
2173 char *p = signature->chars();
2180 types[i++] = get_one_type (p);
2183 type compute_return_type (_Jv_Utf8Const *signature)
2185 char *p = signature->chars();
2189 return get_one_type (p);
2192 void check_return_type (type onstack)
2194 type rt = compute_return_type (current_method->self->signature);
2195 if (! rt.compatible (onstack, this))
2196 verify_fail ("incompatible return type");
2199 // Initialize the stack for the new method. Returns true if this
2200 // method is an instance initializer.
2201 bool initialize_stack ()
2204 bool is_init = _Jv_equalUtf8Consts (current_method->self->name,
2206 bool is_clinit = _Jv_equalUtf8Consts (current_method->self->name,
2209 using namespace java::lang::reflect;
2210 if (! Modifier::isStatic (current_method->self->accflags))
2212 type kurr (current_class, this);
2215 kurr.set_uninitialized (type::SELF, this);
2219 verify_fail ("<clinit> method must be static");
2220 set_variable (0, kurr);
2221 current_state->set_this_type (kurr);
2227 verify_fail ("<init> method must be non-static");
2230 // We have to handle wide arguments specially here.
2231 int arg_count = _Jv_count_arguments (current_method->self->signature);
2232 type arg_types[arg_count];
2233 compute_argument_types (current_method->self->signature, arg_types);
2234 for (int i = 0; i < arg_count; ++i)
2236 set_variable (var, arg_types[i]);
2238 if (arg_types[i].iswide ())
2245 void verify_instructions_0 ()
2247 current_state = new state (current_method->max_stack,
2248 current_method->max_locals);
2253 // True if we are verifying an instance initializer.
2254 bool this_is_init = initialize_stack ();
2256 states = (linked<state> **) _Jv_Malloc (sizeof (linked<state> *)
2257 * current_method->code_length);
2258 for (int i = 0; i < current_method->code_length; ++i)
2261 next_verify_state = NULL;
2265 // If the PC was invalidated, get a new one from the work list.
2266 if (PC == state::NO_NEXT)
2268 state *new_state = pop_jump ();
2269 // If it is null, we're done.
2270 if (new_state == NULL)
2273 PC = new_state->get_pc ();
2274 debug_print ("== State pop from pending list\n");
2275 // Set up the current state.
2276 current_state->copy (new_state, current_method->max_stack,
2277 current_method->max_locals);
2281 // We only have to do this checking in the situation where
2282 // control flow falls through from the previous
2283 // instruction. Otherwise merging is done at the time we
2284 // push the branch. Note that we'll catch the
2285 // off-the-end problem just below.
2286 if (PC < current_method->code_length && states[PC] != NULL)
2288 // We've already visited this instruction. So merge
2289 // the states together. It is simplest, but not most
2290 // efficient, to just always invalidate the PC here.
2291 merge_into (PC, current_state);
2297 // Control can't fall off the end of the bytecode. We need to
2298 // check this in both cases, not just the fall-through case,
2299 // because we don't check to see whether a `jsr' appears at
2300 // the end of the bytecode until we process a `ret'.
2301 if (PC >= current_method->code_length)
2302 verify_fail ("fell off end");
2304 // We only have to keep saved state at branch targets. If
2305 // we're at a branch target and the state here hasn't been set
2306 // yet, we set it now. You might notice that `ret' targets
2307 // won't necessarily have FLAG_BRANCH_TARGET set. This
2308 // doesn't matter, since those states will be filled in by
2310 if (states[PC] == NULL && (flags[PC] & FLAG_BRANCH_TARGET))
2311 add_new_state (PC, current_state);
2313 // Set this before handling exceptions so that debug output is
2317 // Update states for all active exception handlers. Ordinarily
2318 // there are not many exception handlers. So we simply run
2319 // through them all.
2320 for (int i = 0; i < current_method->exc_count; ++i)
2322 if (PC >= exception[i].start_pc.i && PC < exception[i].end_pc.i)
2324 type handler (&java::lang::Throwable::class$, this);
2325 if (exception[i].handler_type.i != 0)
2326 handler = check_class_constant (exception[i].handler_type.i);
2327 push_exception_jump (handler, exception[i].handler_pc.i);
2331 current_state->print (" ", PC, current_method->max_stack,
2332 current_method->max_locals);
2333 java_opcode opcode = (java_opcode) bytecode[PC++];
2339 case op_aconst_null:
2340 push_type (null_type);
2350 push_type (int_type);
2355 push_type (long_type);
2361 push_type (float_type);
2366 push_type (double_type);
2371 push_type (int_type);
2376 push_type (int_type);
2380 push_type (check_constant (get_byte ()));
2383 push_type (check_constant (get_ushort ()));
2386 push_type (check_wide_constant (get_ushort ()));
2390 push_type (get_variable (get_byte (), int_type));
2393 push_type (get_variable (get_byte (), long_type));
2396 push_type (get_variable (get_byte (), float_type));
2399 push_type (get_variable (get_byte (), double_type));
2402 push_type (get_variable (get_byte (), reference_type));
2409 push_type (get_variable (opcode - op_iload_0, int_type));
2415 push_type (get_variable (opcode - op_lload_0, long_type));
2421 push_type (get_variable (opcode - op_fload_0, float_type));
2427 push_type (get_variable (opcode - op_dload_0, double_type));
2433 push_type (get_variable (opcode - op_aload_0, reference_type));
2436 pop_type (int_type);
2437 push_type (require_array_type (pop_init_ref (reference_type),
2441 pop_type (int_type);
2442 push_type (require_array_type (pop_init_ref (reference_type),
2446 pop_type (int_type);
2447 push_type (require_array_type (pop_init_ref (reference_type),
2451 pop_type (int_type);
2452 push_type (require_array_type (pop_init_ref (reference_type),
2456 pop_type (int_type);
2457 push_type (require_array_type (pop_init_ref (reference_type),
2461 pop_type (int_type);
2462 require_array_type (pop_init_ref (reference_type), byte_type);
2463 push_type (int_type);
2466 pop_type (int_type);
2467 require_array_type (pop_init_ref (reference_type), char_type);
2468 push_type (int_type);
2471 pop_type (int_type);
2472 require_array_type (pop_init_ref (reference_type), short_type);
2473 push_type (int_type);
2476 set_variable (get_byte (), pop_type (int_type));
2479 set_variable (get_byte (), pop_type (long_type));
2482 set_variable (get_byte (), pop_type (float_type));
2485 set_variable (get_byte (), pop_type (double_type));
2488 set_variable (get_byte (), pop_ref_or_return ());
2494 set_variable (opcode - op_istore_0, pop_type (int_type));
2500 set_variable (opcode - op_lstore_0, pop_type (long_type));
2506 set_variable (opcode - op_fstore_0, pop_type (float_type));
2512 set_variable (opcode - op_dstore_0, pop_type (double_type));
2518 set_variable (opcode - op_astore_0, pop_ref_or_return ());
2521 pop_type (int_type);
2522 pop_type (int_type);
2523 require_array_type (pop_init_ref (reference_type), int_type);
2526 pop_type (long_type);
2527 pop_type (int_type);
2528 require_array_type (pop_init_ref (reference_type), long_type);
2531 pop_type (float_type);
2532 pop_type (int_type);
2533 require_array_type (pop_init_ref (reference_type), float_type);
2536 pop_type (double_type);
2537 pop_type (int_type);
2538 require_array_type (pop_init_ref (reference_type), double_type);
2541 pop_type (reference_type);
2542 pop_type (int_type);
2543 require_array_type (pop_init_ref (reference_type), reference_type);
2546 pop_type (int_type);
2547 pop_type (int_type);
2548 require_array_type (pop_init_ref (reference_type), byte_type);
2551 pop_type (int_type);
2552 pop_type (int_type);
2553 require_array_type (pop_init_ref (reference_type), char_type);
2556 pop_type (int_type);
2557 pop_type (int_type);
2558 require_array_type (pop_init_ref (reference_type), short_type);
2565 type t = pop_raw ();
2589 type t2 = pop_raw ();
2604 type t = pop_raw ();
2619 type t1 = pop_raw ();
2636 type t1 = pop_raw ();
2639 type t2 = pop_raw ();
2657 type t3 = pop_raw ();
2695 pop_type (int_type);
2696 push_type (pop_type (int_type));
2706 pop_type (long_type);
2707 push_type (pop_type (long_type));
2712 pop_type (int_type);
2713 push_type (pop_type (long_type));
2720 pop_type (float_type);
2721 push_type (pop_type (float_type));
2728 pop_type (double_type);
2729 push_type (pop_type (double_type));
2735 push_type (pop_type (int_type));
2738 push_type (pop_type (long_type));
2741 push_type (pop_type (float_type));
2744 push_type (pop_type (double_type));
2747 get_variable (get_byte (), int_type);
2751 pop_type (int_type);
2752 push_type (long_type);
2755 pop_type (int_type);
2756 push_type (float_type);
2759 pop_type (int_type);
2760 push_type (double_type);
2763 pop_type (long_type);
2764 push_type (int_type);
2767 pop_type (long_type);
2768 push_type (float_type);
2771 pop_type (long_type);
2772 push_type (double_type);
2775 pop_type (float_type);
2776 push_type (int_type);
2779 pop_type (float_type);
2780 push_type (long_type);
2783 pop_type (float_type);
2784 push_type (double_type);
2787 pop_type (double_type);
2788 push_type (int_type);
2791 pop_type (double_type);
2792 push_type (long_type);
2795 pop_type (double_type);
2796 push_type (float_type);
2799 pop_type (long_type);
2800 pop_type (long_type);
2801 push_type (int_type);
2805 pop_type (float_type);
2806 pop_type (float_type);
2807 push_type (int_type);
2811 pop_type (double_type);
2812 pop_type (double_type);
2813 push_type (int_type);
2821 pop_type (int_type);
2822 push_jump (get_short ());
2830 pop_type (int_type);
2831 pop_type (int_type);
2832 push_jump (get_short ());
2836 pop_type (reference_type);
2837 pop_type (reference_type);
2838 push_jump (get_short ());
2841 push_jump (get_short ());
2845 handle_jsr_insn (get_short ());
2848 handle_ret_insn (get_byte ());
2850 case op_tableswitch:
2852 pop_type (int_type);
2854 push_jump (get_int ());
2855 jint low = get_int ();
2856 jint high = get_int ();
2857 // Already checked LOW -vs- HIGH.
2858 for (int i = low; i <= high; ++i)
2859 push_jump (get_int ());
2864 case op_lookupswitch:
2866 pop_type (int_type);
2868 push_jump (get_int ());
2869 jint npairs = get_int ();
2870 // Already checked NPAIRS >= 0.
2872 for (int i = 0; i < npairs; ++i)
2874 jint key = get_int ();
2875 if (i > 0 && key <= lastkey)
2876 verify_fail ("lookupswitch pairs unsorted", start_PC);
2878 push_jump (get_int ());
2884 check_return_type (pop_type (int_type));
2888 check_return_type (pop_type (long_type));
2892 check_return_type (pop_type (float_type));
2896 check_return_type (pop_type (double_type));
2900 check_return_type (pop_init_ref (reference_type));
2904 // We only need to check this when the return type is
2905 // void, because all instance initializers return void.
2907 current_state->check_this_initialized (this);
2908 check_return_type (void_type);
2912 push_type (check_field_constant (get_ushort ()));
2915 pop_type (check_field_constant (get_ushort ()));
2920 type field = check_field_constant (get_ushort (), &klass);
2928 type field = check_field_constant (get_ushort (), &klass, true);
2934 case op_invokevirtual:
2935 case op_invokespecial:
2936 case op_invokestatic:
2937 case op_invokeinterface:
2939 _Jv_Utf8Const *method_name, *method_signature;
2941 = check_method_constant (get_ushort (),
2942 opcode == op_invokeinterface,
2945 // NARGS is only used when we're processing
2946 // invokeinterface. It is simplest for us to compute it
2947 // here and then verify it later.
2949 if (opcode == op_invokeinterface)
2951 nargs = get_byte ();
2952 if (get_byte () != 0)
2953 verify_fail ("invokeinterface dummy byte is wrong");
2956 bool is_init = false;
2957 if (_Jv_equalUtf8Consts (method_name, gcj::init_name))
2960 if (opcode != op_invokespecial)
2961 verify_fail ("can't invoke <init>");
2963 else if (method_name->first() == '<')
2964 verify_fail ("can't invoke method starting with `<'");
2966 // Pop arguments and check types.
2967 int arg_count = _Jv_count_arguments (method_signature);
2968 type arg_types[arg_count];
2969 compute_argument_types (method_signature, arg_types);
2970 for (int i = arg_count - 1; i >= 0; --i)
2972 // This is only used for verifying the byte for
2974 nargs -= arg_types[i].depth ();
2975 pop_init_ref (arg_types[i]);
2978 if (opcode == op_invokeinterface
2980 verify_fail ("wrong argument count for invokeinterface");
2982 if (opcode != op_invokestatic)
2984 type t = class_type;
2987 // In this case the PC doesn't matter.
2988 t.set_uninitialized (type::UNINIT, this);
2989 // FIXME: check to make sure that the <init>
2990 // call is to the right class.
2991 // It must either be super or an exact class
2994 type raw = pop_raw ();
2995 if (! t.compatible (raw, this))
2996 verify_fail ("incompatible type on stack");
2999 current_state->set_initialized (raw.get_pc (),
3000 current_method->max_locals);
3003 type rt = compute_return_type (method_signature);
3011 type t = check_class_constant (get_ushort ());
3013 verify_fail ("type is array");
3014 t.set_uninitialized (start_PC, this);
3021 int atype = get_byte ();
3022 // We intentionally have chosen constants to make this
3024 if (atype < boolean_type || atype > long_type)
3025 verify_fail ("type not primitive", start_PC);
3026 pop_type (int_type);
3027 type t (construct_primitive_array_type (type_val (atype)), this);
3032 pop_type (int_type);
3033 push_type (check_class_constant (get_ushort ()).to_array (this));
3035 case op_arraylength:
3037 type t = pop_init_ref (reference_type);
3038 if (! t.isarray () && ! t.isnull ())
3039 verify_fail ("array type expected");
3040 push_type (int_type);
3044 pop_type (type (&java::lang::Throwable::class$, this));
3048 pop_init_ref (reference_type);
3049 push_type (check_class_constant (get_ushort ()));
3052 pop_init_ref (reference_type);
3053 check_class_constant (get_ushort ());
3054 push_type (int_type);
3056 case op_monitorenter:
3057 pop_init_ref (reference_type);
3059 case op_monitorexit:
3060 pop_init_ref (reference_type);
3064 switch (get_byte ())
3067 push_type (get_variable (get_ushort (), int_type));
3070 push_type (get_variable (get_ushort (), long_type));
3073 push_type (get_variable (get_ushort (), float_type));
3076 push_type (get_variable (get_ushort (), double_type));
3079 push_type (get_variable (get_ushort (), reference_type));
3082 set_variable (get_ushort (), pop_type (int_type));
3085 set_variable (get_ushort (), pop_type (long_type));
3088 set_variable (get_ushort (), pop_type (float_type));
3091 set_variable (get_ushort (), pop_type (double_type));
3094 set_variable (get_ushort (), pop_init_ref (reference_type));
3097 handle_ret_insn (get_short ());
3100 get_variable (get_ushort (), int_type);
3104 verify_fail ("unrecognized wide instruction", start_PC);
3108 case op_multianewarray:
3110 type atype = check_class_constant (get_ushort ());
3111 int dim = get_byte ();
3113 verify_fail ("too few dimensions to multianewarray", start_PC);
3114 atype.verify_dimensions (dim, this);
3115 for (int i = 0; i < dim; ++i)
3116 pop_type (int_type);
3122 pop_type (reference_type);
3123 push_jump (get_short ());
3126 push_jump (get_int ());
3130 handle_jsr_insn (get_int ());
3133 // These are unused here, but we call them out explicitly
3134 // so that -Wswitch-enum doesn't complain.
3140 case op_putstatic_1:
3141 case op_putstatic_2:
3142 case op_putstatic_4:
3143 case op_putstatic_8:
3144 case op_putstatic_a:
3146 case op_getfield_2s:
3147 case op_getfield_2u:
3151 case op_getstatic_1:
3152 case op_getstatic_2s:
3153 case op_getstatic_2u:
3154 case op_getstatic_4:
3155 case op_getstatic_8:
3156 case op_getstatic_a:
3159 // Unrecognized opcode.
3160 verify_fail ("unrecognized instruction in verify_instructions_0",
3168 void verify_instructions ()
3171 verify_instructions_0 ();
3174 _Jv_BytecodeVerifier (_Jv_InterpMethod *m)
3176 // We just print the text as utf-8. This is just for debugging
3178 debug_print ("--------------------------------\n");
3179 debug_print ("-- Verifying method `%s'\n", m->self->name->chars());
3182 bytecode = m->bytecode ();
3183 exception = m->exceptions ();
3184 current_class = m->defining_class;
3192 ~_Jv_BytecodeVerifier ()
3197 while (utf8_list != NULL)
3199 linked<_Jv_Utf8Const> *n = utf8_list->next;
3200 _Jv_Free (utf8_list);
3204 while (isect_list != NULL)
3206 ref_intersection *next = isect_list->alloc_next;
3213 for (int i = 0; i < current_method->code_length; ++i)
3215 linked<state> *iter = states[i];
3216 while (iter != NULL)
3218 linked<state> *next = iter->next;
3230 _Jv_VerifyMethod (_Jv_InterpMethod *meth)
3232 _Jv_BytecodeVerifier v (meth);
3233 v.verify_instructions ();
3236 #endif /* INTERPRETER */