1 /*
  2  * Copyright (c) 2005, 2024, 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 #ifndef SHARE_CODE_DEPENDENCIES_HPP
 26 #define SHARE_CODE_DEPENDENCIES_HPP
 27 
 28 #include "ci/ciCallSite.hpp"
 29 #include "ci/ciKlass.hpp"
 30 #include "ci/ciMethod.hpp"
 31 #include "ci/ciMethodHandle.hpp"
 32 #include "code/compressedStream.hpp"
 33 #include "code/nmethod.hpp"
 34 #include "memory/resourceArea.hpp"
 35 #include "runtime/safepointVerifiers.hpp"
 36 #include "utilities/growableArray.hpp"
 37 
 38 //** Dependencies represent assertions (approximate invariants) within
 39 // the runtime system, e.g. class hierarchy changes.  An example is an
 40 // assertion that a given method is not overridden; another example is
 41 // that a type has only one concrete subtype.  Compiled code which
 42 // relies on such assertions must be discarded if they are overturned
 43 // by changes in the runtime system.  We can think of these assertions
 44 // as approximate invariants, because we expect them to be overturned
 45 // very infrequently.  We are willing to perform expensive recovery
 46 // operations when they are overturned.  The benefit, of course, is
 47 // performing optimistic optimizations (!) on the object code.
 48 //
 49 // Changes in the class hierarchy due to dynamic linking or
 50 // class evolution can violate dependencies.  There is enough
 51 // indexing between classes and nmethods to make dependency
 52 // checking reasonably efficient.
 53 
 54 class ciEnv;
 55 class nmethod;
 56 class OopRecorder;
 57 class xmlStream;
 58 class CompileLog;
 59 class CompileTask;
 60 class DepChange;
 61 class   KlassDepChange;
 62 class     NewKlassDepChange;
 63 class     KlassInitDepChange;
 64 class   CallSiteDepChange;
 65 class NoSafepointVerifier;
 66 
 67 class Dependencies: public ResourceObj {
 68  public:
 69   // Note: In the comments on dependency types, most uses of the terms
 70   // subtype and supertype are used in a "non-strict" or "inclusive"
 71   // sense, and are starred to remind the reader of this fact.
 72   // Strict uses of the terms use the word "proper".
 73   //
 74   // Specifically, every class is its own subtype* and supertype*.
 75   // (This trick is easier than continually saying things like "Y is a
 76   // subtype of X or X itself".)
 77   //
 78   // Sometimes we write X > Y to mean X is a proper supertype of Y.
 79   // The notation X > {Y, Z} means X has proper subtypes Y, Z.
 80   // The notation X.m > Y means that Y inherits m from X, while
 81   // X.m > Y.m means Y overrides X.m.  A star denotes abstractness,
 82   // as *I > A, meaning (abstract) interface I is a super type of A,
 83   // or A.*m > B.m, meaning B.m implements abstract method A.m.
 84   //
 85   // In this module, the terms "subtype" and "supertype" refer to
 86   // Java-level reference type conversions, as detected by
 87   // "instanceof" and performed by "checkcast" operations.  The method
 88   // Klass::is_subtype_of tests these relations.  Note that "subtype"
 89   // is richer than "subclass" (as tested by Klass::is_subclass_of),
 90   // since it takes account of relations involving interface and array
 91   // types.
 92   //
 93   // To avoid needless complexity, dependencies involving array types
 94   // are not accepted.  If you need to make an assertion about an
 95   // array type, make the assertion about its corresponding element
 96   // types.  Any assertion that might change about an array type can
 97   // be converted to an assertion about its element type.
 98   //
 99   // Most dependencies are evaluated over a "context type" CX, which
100   // stands for the set Subtypes(CX) of every Java type that is a subtype*
101   // of CX.  When the system loads a new class or interface N, it is
102   // responsible for re-evaluating changed dependencies whose context
103   // type now includes N, that is, all super types of N.
104   //
105   enum DepType {
106     // _type is initially set to -1, to prevent "already at end" assert
107     undefined_dependency = -1,
108 
109     end_marker = 0,
110 
111     // An 'evol' dependency simply notes that the contents of the
112     // method were used.  If it evolves (is replaced), the nmethod
113     // must be recompiled.  No other dependencies are implied.
114     evol_method,
115     FIRST_TYPE = evol_method,
116 
117     // A context type CX is a leaf it if has no proper subtype.
118     leaf_type,
119 
120     // An abstract class CX has exactly one concrete subtype CC.
121     abstract_with_unique_concrete_subtype,
122 
123     // Given a method M1 and a context class CX, the set MM(CX, M1) of
124     // "concrete matching methods" in CX of M1 is the set of every
125     // concrete M2 for which it is possible to create an invokevirtual
126     // or invokeinterface call site that can reach either M1 or M2.
127     // That is, M1 and M2 share a name, signature, and vtable index.
128     // We wish to notice when the set MM(CX, M1) is just {M1}, or
129     // perhaps a set of two {M1,M2}, and issue dependencies on this.
130 
131     // The set MM(CX, M1) can be computed by starting with any matching
132     // concrete M2 that is inherited into CX, and then walking the
133     // subtypes* of CX looking for concrete definitions.
134 
135     // The parameters to this dependency are the method M1 and the
136     // context class CX.  M1 must be either inherited in CX or defined
137     // in a subtype* of CX.  It asserts that MM(CX, M1) is no greater
138     // than {M1}.
139     unique_concrete_method_2, // one unique concrete method under CX
140 
141     // In addition to the method M1 and the context class CX, the parameters
142     // to this dependency are the resolved class RC1 and the
143     // resolved method RM1. It asserts that MM(CX, M1, RC1, RM1)
144     // is no greater than {M1}. RC1 and RM1 are used to improve the precision
145     // of the analysis.
146     unique_concrete_method_4, // one unique concrete method under CX
147 
148     // This dependency asserts that interface CX has a unique implementor class.
149     unique_implementor, // one unique implementor under CX
150 
151     // This dependency asserts that no instances of class or it's
152     // subclasses require finalization registration.
153     no_finalizable_subclasses,
154 
155     // This dependency asserts when the CallSite.target value changed.
156     call_site_target_value,
157 
158     TYPE_LIMIT
159   };
160   enum {
161     LG2_TYPE_LIMIT = 4,  // assert(TYPE_LIMIT <= (1<<LG2_TYPE_LIMIT))
162 
163     // handy categorizations of dependency types:
164     all_types           = ((1 << TYPE_LIMIT) - 1) & ((~0u) << FIRST_TYPE),
165 
166     non_klass_types     = (1 << call_site_target_value),
167     klass_types         = all_types & ~non_klass_types,
168 
169     non_ctxk_types      = (1 << evol_method) | (1 << call_site_target_value),
170     implicit_ctxk_types = 0,
171     explicit_ctxk_types = all_types & ~(non_ctxk_types | implicit_ctxk_types),
172 
173     max_arg_count = 4,   // current maximum number of arguments (incl. ctxk)
174 
175     // A "context type" is a class or interface that
176     // provides context for evaluating a dependency.
177     // When present, it is one of the arguments (dep_context_arg).
178     //
179     // If a dependency does not have a context type, there is a
180     // default context, depending on the type of the dependency.
181     // This bit signals that a default context has been compressed away.
182     default_context_type_bit = (1<<LG2_TYPE_LIMIT)
183   };
184 
185   static const char* dep_name(DepType dept);
186   static int         dep_args(DepType dept);
187 
188   static bool is_klass_type(           DepType dept) { return dept_in_mask(dept, klass_types        ); }
189 
190   static bool has_explicit_context_arg(DepType dept) { return dept_in_mask(dept, explicit_ctxk_types); }
191   static bool has_implicit_context_arg(DepType dept) { return dept_in_mask(dept, implicit_ctxk_types); }
192 
193   static int           dep_context_arg(DepType dept) { return has_explicit_context_arg(dept) ? 0 : -1; }
194   static int  dep_implicit_context_arg(DepType dept) { return has_implicit_context_arg(dept) ? 0 : -1; }
195 
196   static void check_valid_dependency_type(DepType dept);
197 
198 #if INCLUDE_JVMCI
199   // A Metadata* or object value recorded in an OopRecorder
200   class DepValue {
201    private:
202     // Unique identifier of the value within the associated OopRecorder that
203     // encodes both the category of the value (0: invalid, positive: metadata, negative: object)
204     // and the index within a category specific array (metadata: index + 1, object: -(index + 1))
205     int _id;
206 
207    public:
208     DepValue() : _id(0) {}
209     DepValue(OopRecorder* rec, Metadata* metadata, DepValue* candidate = nullptr) {
210       assert(candidate == nullptr || candidate->is_metadata(), "oops");
211       if (candidate != nullptr && candidate->as_metadata(rec) == metadata) {
212         _id = candidate->_id;
213       } else {
214         _id = rec->find_index(metadata) + 1;
215       }
216     }
217     DepValue(OopRecorder* rec, jobject obj, DepValue* candidate = nullptr) {
218       assert(candidate == nullptr || candidate->is_object(), "oops");
219       if (candidate != nullptr && candidate->as_object(rec) == obj) {
220         _id = candidate->_id;
221       } else {
222         _id = -(rec->find_index(obj) + 1);
223       }
224     }
225 
226     // Used to sort values in ascending order of index() with metadata values preceding object values
227     int sort_key() const { return -_id; }
228 
229     bool operator == (const DepValue& other) const   { return other._id == _id; }
230 
231     bool is_valid() const             { return _id != 0; }
232     int  index() const                { assert(is_valid(), "oops"); return _id < 0 ? -(_id + 1) : _id - 1; }
233     bool is_metadata() const          { assert(is_valid(), "oops"); return _id > 0; }
234     bool is_object() const            { assert(is_valid(), "oops"); return _id < 0; }
235 
236     Metadata*  as_metadata(OopRecorder* rec) const    { assert(is_metadata(), "oops"); return rec->metadata_at(index()); }
237     Klass*     as_klass(OopRecorder* rec) const {
238       Metadata* m = as_metadata(rec);
239       assert(m != nullptr, "as_metadata returned nullptr");
240       assert(m->is_klass(), "oops");
241       return (Klass*) m;
242     }
243     Method*    as_method(OopRecorder* rec) const {
244       Metadata* m = as_metadata(rec);
245       assert(m != nullptr, "as_metadata returned nullptr");
246       assert(m->is_method(), "oops");
247       return (Method*) m;
248     }
249     jobject    as_object(OopRecorder* rec) const      { assert(is_object(), "oops"); return rec->oop_at(index()); }
250   };
251 #endif // INCLUDE_JVMCI
252 
253  private:
254   // State for writing a new set of dependencies:
255   GrowableArray<int>*       _dep_seen;  // (seen[h->ident] & (1<<dept))
256   GrowableArray<ciBaseObject*>*  _deps[TYPE_LIMIT];
257 #if INCLUDE_JVMCI
258   bool _using_dep_values;
259   GrowableArray<DepValue>*  _dep_values[TYPE_LIMIT];
260 #endif
261 
262   static const char* _dep_name[TYPE_LIMIT];
263   static int         _dep_args[TYPE_LIMIT];
264 
265   static bool dept_in_mask(DepType dept, int mask) {
266     return (int)dept >= 0 && dept < TYPE_LIMIT && ((1<<dept) & mask) != 0;
267   }
268 
269   bool note_dep_seen(int dept, ciBaseObject* x) {
270     assert(dept < BitsPerInt, "oob");
271     int x_id = x->ident();
272     assert(_dep_seen != nullptr, "deps must be writable");
273     int seen = _dep_seen->at_grow(x_id, 0);
274     _dep_seen->at_put(x_id, seen | (1<<dept));
275     // return true if we've already seen dept/x
276     return (seen & (1<<dept)) != 0;
277   }
278 
279 #if INCLUDE_JVMCI
280   bool note_dep_seen(int dept, DepValue x) {
281     assert(dept < BitsPerInt, "oops");
282     // place metadata deps at even indexes, object deps at odd indexes
283     int x_id = x.is_metadata() ? x.index() * 2 : (x.index() * 2) + 1;
284     assert(_dep_seen != nullptr, "deps must be writable");
285     int seen = _dep_seen->at_grow(x_id, 0);
286     _dep_seen->at_put(x_id, seen | (1<<dept));
287     // return true if we've already seen dept/x
288     return (seen & (1<<dept)) != 0;
289   }
290 #endif
291 
292   bool maybe_merge_ctxk(GrowableArray<ciBaseObject*>* deps,
293                         int ctxk_i, ciKlass* ctxk);
294 #if INCLUDE_JVMCI
295   bool maybe_merge_ctxk(GrowableArray<DepValue>* deps,
296                         int ctxk_i, DepValue ctxk);
297 #endif
298 
299   void sort_all_deps();
300   size_t estimate_size_in_bytes();
301 
302   // Initialize _deps, etc.
303   void initialize(ciEnv* env);
304 
305   // State for making a new set of dependencies:
306   OopRecorder* _oop_recorder;
307 
308   // Logging support
309   CompileLog* _log;
310 
311   address  _content_bytes;  // everything but the oop references, encoded
312   size_t   _size_in_bytes;
313 
314  public:
315   // Make a new empty dependencies set.
316   Dependencies(ciEnv* env) {
317     initialize(env);
318   }
319 #if INCLUDE_JVMCI
320   Dependencies(Arena* arena, OopRecorder* oop_recorder, CompileLog* log);
321 #endif
322 
323  private:
324   // Check for a valid context type.
325   // Enforce the restriction against array types.
326   static void check_ctxk(ciKlass* ctxk) {
327     assert(ctxk->is_instance_klass(), "java types only");
328   }
329   static void check_ctxk_concrete(ciKlass* ctxk) {
330     assert(is_concrete_klass(ctxk->as_instance_klass()), "must be concrete");
331   }
332   static void check_ctxk_abstract(ciKlass* ctxk) {
333     check_ctxk(ctxk);
334     assert(!is_concrete_klass(ctxk->as_instance_klass()), "must be abstract");
335   }
336   static void check_unique_method(ciKlass* ctxk, ciMethod* m) {
337     assert(!m->can_be_statically_bound(ctxk->as_instance_klass()) || ctxk->is_interface(), "redundant");
338   }
339   static void check_unique_implementor(ciInstanceKlass* ctxk, ciInstanceKlass* uniqk) {
340     assert(ctxk->implementor() == uniqk, "not a unique implementor");
341   }
342 
343   void assert_common_1(DepType dept, ciBaseObject* x);
344   void assert_common_2(DepType dept, ciBaseObject* x0, ciBaseObject* x1);
345   void assert_common_4(DepType dept, ciKlass* ctxk, ciBaseObject* x1, ciBaseObject* x2, ciBaseObject* x3);
346 
347  public:
348   // Adding assertions to a new dependency set at compile time:
349   void assert_evol_method(ciMethod* m);
350   void assert_leaf_type(ciKlass* ctxk);
351   void assert_abstract_with_unique_concrete_subtype(ciKlass* ctxk, ciKlass* conck);
352   void assert_unique_concrete_method(ciKlass* ctxk, ciMethod* uniqm);
353   void assert_unique_concrete_method(ciKlass* ctxk, ciMethod* uniqm, ciKlass* resolved_klass, ciMethod* resolved_method);
354   void assert_unique_implementor(ciInstanceKlass* ctxk, ciInstanceKlass* uniqk);
355   void assert_has_no_finalizable_subclasses(ciKlass* ctxk);
356   void assert_call_site_target_value(ciCallSite* call_site, ciMethodHandle* method_handle);
357 #if INCLUDE_JVMCI
358  private:
359   static void check_ctxk(Klass* ctxk) {
360     assert(ctxk->is_instance_klass(), "java types only");
361   }
362   static void check_ctxk_abstract(Klass* ctxk) {
363     check_ctxk(ctxk);
364     assert(ctxk->is_abstract(), "must be abstract");
365   }
366   static void check_unique_method(Klass* ctxk, Method* m) {
367     assert(!m->can_be_statically_bound(InstanceKlass::cast(ctxk)), "redundant");
368   }
369 
370   void assert_common_1(DepType dept, DepValue x);
371   void assert_common_2(DepType dept, DepValue x0, DepValue x1);
372 
373  public:
374   void assert_evol_method(Method* m);
375   void assert_has_no_finalizable_subclasses(Klass* ctxk);
376   void assert_leaf_type(Klass* ctxk);
377   void assert_unique_implementor(InstanceKlass* ctxk, InstanceKlass* uniqk);
378   void assert_unique_concrete_method(Klass* ctxk, Method* uniqm);
379   void assert_abstract_with_unique_concrete_subtype(Klass* ctxk, Klass* conck);
380   void assert_call_site_target_value(oop callSite, oop methodHandle);
381 #endif // INCLUDE_JVMCI
382 
383   // Define whether a given method or type is concrete.
384   // These methods define the term "concrete" as used in this module.
385   // For this module, an "abstract" class is one which is non-concrete.
386   //
387   // Future optimizations may allow some classes to remain
388   // non-concrete until their first instantiation, and allow some
389   // methods to remain non-concrete until their first invocation.
390   // In that case, there would be a middle ground between concrete
391   // and abstract (as defined by the Java language and VM).
392   static bool is_concrete_klass(Klass* k);    // k is instantiable
393   static bool is_concrete_method(Method* m, Klass* k);  // m is invocable
394   static Klass* find_finalizable_subclass(InstanceKlass* ik);
395 
396   static bool is_concrete_root_method(Method* uniqm, InstanceKlass* ctxk);
397   static Klass* find_witness_AME(InstanceKlass* ctxk, Method* m, KlassDepChange* changes = nullptr);
398 
399   // These versions of the concreteness queries work through the CI.
400   // The CI versions are allowed to skew sometimes from the VM
401   // (oop-based) versions.  The cost of such a difference is a
402   // (safely) aborted compilation, or a deoptimization, or a missed
403   // optimization opportunity.
404   //
405   // In order to prevent spurious assertions, query results must
406   // remain stable within any single ciEnv instance.  (I.e., they must
407   // not go back into the VM to get their value; they must cache the
408   // bit in the CI, either eagerly or lazily.)
409   static bool is_concrete_klass(ciInstanceKlass* k); // k appears instantiable
410   static bool has_finalizable_subclass(ciInstanceKlass* k);
411 
412   // As a general rule, it is OK to compile under the assumption that
413   // a given type or method is concrete, even if it at some future
414   // point becomes abstract.  So dependency checking is one-sided, in
415   // that it permits supposedly concrete classes or methods to turn up
416   // as really abstract.  (This shouldn't happen, except during class
417   // evolution, but that's the logic of the checking.)  However, if a
418   // supposedly abstract class or method suddenly becomes concrete, a
419   // dependency on it must fail.
420 
421   // Checking old assertions at run-time (in the VM only):
422   static Klass* check_evol_method(Method* m);
423   static Klass* check_leaf_type(InstanceKlass* ctxk);
424   static Klass* check_abstract_with_unique_concrete_subtype(InstanceKlass* ctxk, Klass* conck, NewKlassDepChange* changes = nullptr);
425   static Klass* check_unique_implementor(InstanceKlass* ctxk, Klass* uniqk, NewKlassDepChange* changes = nullptr);
426   static Klass* check_unique_concrete_method(InstanceKlass* ctxk, Method* uniqm, NewKlassDepChange* changes = nullptr);
427   static Klass* check_unique_concrete_method(InstanceKlass* ctxk, Method* uniqm, Klass* resolved_klass, Method* resolved_method, KlassDepChange* changes = nullptr);
428   static Klass* check_has_no_finalizable_subclasses(InstanceKlass* ctxk, NewKlassDepChange* changes = nullptr);
429   static Klass* check_call_site_target_value(oop call_site, oop method_handle, CallSiteDepChange* changes = nullptr);
430   // A returned Klass* is nullptr if the dependency assertion is still
431   // valid.  A non-nullptr Klass* is a 'witness' to the assertion
432   // failure, a point in the class hierarchy where the assertion has
433   // been proven false.  For example, if check_leaf_type returns
434   // non-nullptr, the value is a subtype of the supposed leaf type.  This
435   // witness value may be useful for logging the dependency failure.
436   // Note that, when a dependency fails, there may be several possible
437   // witnesses to the failure.  The value returned from the check_foo
438   // method is chosen arbitrarily.
439 
440   // The 'changes' value, if non-null, requests a limited spot-check
441   // near the indicated recent changes in the class hierarchy.
442   // It is used by DepStream::spot_check_dependency_at.
443 
444   // Detecting possible new assertions:
445   static Klass*  find_unique_concrete_subtype(InstanceKlass* ctxk);
446   static Method* find_unique_concrete_method(InstanceKlass* ctxk, Method* m,
447                                              Klass** participant = nullptr); // out parameter
448   static Method* find_unique_concrete_method(InstanceKlass* ctxk, Method* m, Klass* resolved_klass, Method* resolved_method);
449 
450 #ifdef ASSERT
451   static bool verify_method_context(InstanceKlass* ctxk, Method* m);
452 #endif // ASSERT
453 
454   // Create the encoding which will be stored in an nmethod.
455   void encode_content_bytes();
456 
457   address content_bytes() {
458     assert(_content_bytes != nullptr, "encode it first");
459     return _content_bytes;
460   }
461   size_t size_in_bytes() {
462     assert(_content_bytes != nullptr, "encode it first");
463     return _size_in_bytes;
464   }
465 
466   void set_content(address content_bytes, int size_in_bytes) {
467     assert(_content_bytes == nullptr, "not intialized expected");
468     _content_bytes = content_bytes;
469     _size_in_bytes = size_in_bytes;
470   }
471 
472   OopRecorder* oop_recorder() { return _oop_recorder; }
473   CompileLog*  log()          { return _log; }
474 
475   void copy_to(nmethod* nm);
476 
477   static bool _verify_in_progress;  // turn off logging dependencies
478 
479   DepType validate_dependencies(CompileTask* task, char** failure_detail = nullptr);
480 
481   void log_all_dependencies();
482 
483   void log_dependency(DepType dept, GrowableArray<ciBaseObject*>* args) {
484     ResourceMark rm;
485     int argslen = args->length();
486     write_dependency_to(log(), dept, args);
487     guarantee(argslen == args->length(),
488               "args array cannot grow inside nested ResoureMark scope");
489   }
490 
491   void log_dependency(DepType dept,
492                       ciBaseObject* x0,
493                       ciBaseObject* x1 = nullptr,
494                       ciBaseObject* x2 = nullptr,
495                       ciBaseObject* x3 = nullptr) {
496     if (log() == nullptr) {
497       return;
498     }
499     ResourceMark rm;
500     GrowableArray<ciBaseObject*>* ciargs =
501                 new GrowableArray<ciBaseObject*>(dep_args(dept));
502     assert (x0 != nullptr, "no log x0");
503     ciargs->push(x0);
504 
505     if (x1 != nullptr) {
506       ciargs->push(x1);
507     }
508     if (x2 != nullptr) {
509       ciargs->push(x2);
510     }
511     if (x3 != nullptr) {
512       ciargs->push(x3);
513     }
514     assert(ciargs->length() == dep_args(dept), "");
515     log_dependency(dept, ciargs);
516   }
517 
518   class DepArgument : public ResourceObj {
519    private:
520     bool  _is_oop;
521     bool  _valid;
522     void* _value;
523    public:
524     DepArgument() : _is_oop(false), _valid(false), _value(nullptr) {}
525     DepArgument(oop v): _is_oop(true), _valid(true), _value(v) {}
526     DepArgument(Metadata* v): _is_oop(false), _valid(true), _value(v) {}
527 
528     bool is_null() const               { return _value == nullptr; }
529     bool is_oop() const                { return _is_oop; }
530     bool is_metadata() const           { return !_is_oop; }
531     bool is_klass() const              { return is_metadata() && metadata_value()->is_klass(); }
532     bool is_method() const             { return is_metadata() && metadata_value()->is_method(); }
533 
534     oop oop_value() const              { assert(_is_oop && _valid, "must be"); return cast_to_oop(_value); }
535     Metadata* metadata_value() const   { assert(!_is_oop && _valid, "must be"); return (Metadata*) _value; }
536   };
537 
538   static void print_dependency(DepType dept,
539                                GrowableArray<DepArgument>* args,
540                                Klass* witness = nullptr, outputStream* st = tty);
541 
542  private:
543   // helper for encoding common context types as zero:
544   static ciKlass* ctxk_encoded_as_null(DepType dept, ciBaseObject* x);
545 
546   static Klass* ctxk_encoded_as_null(DepType dept, Metadata* x);
547 
548   static void write_dependency_to(CompileLog* log,
549                                   DepType dept,
550                                   GrowableArray<ciBaseObject*>* args,
551                                   Klass* witness = nullptr);
552   static void write_dependency_to(CompileLog* log,
553                                   DepType dept,
554                                   GrowableArray<DepArgument>* args,
555                                   Klass* witness = nullptr);
556   static void write_dependency_to(xmlStream* xtty,
557                                   DepType dept,
558                                   GrowableArray<DepArgument>* args,
559                                   Klass* witness = nullptr);
560  public:
561   // Use this to iterate over an nmethod's dependency set.
562   // Works on new and old dependency sets.
563   // Usage:
564   //
565   // ;
566   // Dependencies::DepType dept;
567   // for (Dependencies::DepStream deps(nm); deps.next(); ) {
568   //   ...
569   // }
570   //
571   // The caller must be in the VM, since oops are not wrapped in handles.
572   class DepStream {
573   private:
574     nmethod*              _code;   // null if in a compiler thread
575     Dependencies*         _deps;   // null if not in a compiler thread
576     CompressedReadStream  _bytes;
577 #ifdef ASSERT
578     size_t                _byte_limit;
579 #endif
580 
581     // iteration variables:
582     DepType               _type;
583     int                   _xi[max_arg_count+1];
584 
585     void initial_asserts(size_t byte_limit) NOT_DEBUG({});
586 
587     inline Metadata* recorded_metadata_at(int i);
588     inline oop recorded_oop_at(int i);
589 
590     Klass* check_klass_dependency(KlassDepChange* changes);
591     Klass* check_new_klass_dependency(NewKlassDepChange* changes);
592     Klass* check_klass_init_dependency(KlassInitDepChange* changes);
593     Klass* check_call_site_dependency(CallSiteDepChange* changes);
594 
595     void trace_and_log_witness(Klass* witness);
596 
597   public:
598     DepStream(Dependencies* deps)
599       : _code(nullptr),
600         _deps(deps),
601         _bytes(deps->content_bytes())
602     {
603       initial_asserts(deps->size_in_bytes());
604     }
605     DepStream(nmethod* code)
606       : _code(code),
607         _deps(nullptr),
608         _bytes(code->dependencies_begin())
609     {
610       initial_asserts(code->dependencies_size());
611     }
612 
613     bool next();
614 
615     DepType type()               { return _type; }
616     bool is_oop_argument(int i)  { return type() == call_site_target_value; }
617     uintptr_t get_identifier(int i);
618 
619     int argument_count()         { return dep_args(type()); }
620     int argument_index(int i)    { assert(0 <= i && i < argument_count(), "oob");
621                                    return _xi[i]; }
622     Metadata* argument(int i);     // => recorded_oop_at(argument_index(i))
623     oop argument_oop(int i);         // => recorded_oop_at(argument_index(i))
624     InstanceKlass* context_type();
625 
626     bool is_klass_type()         { return Dependencies::is_klass_type(type()); }
627 
628     Method* method_argument(int i) {
629       Metadata* x = argument(i);
630       assert(x->is_method(), "type");
631       return (Method*) x;
632     }
633     Klass* type_argument(int i) {
634       Metadata* x = argument(i);
635       assert(x->is_klass(), "type");
636       return (Klass*) x;
637     }
638 
639     // The point of the whole exercise:  Is this dep still OK?
640     Klass* check_dependency() {
641       Klass* result = check_klass_dependency(nullptr);
642       if (result != nullptr)  return result;
643       return check_call_site_dependency(nullptr);
644     }
645 
646     // A lighter version:  Checks only around recent changes in a class
647     // hierarchy.  (See Universe::flush_dependents_on.)
648     Klass* spot_check_dependency_at(DepChange& changes);
649 
650     // Log the current dependency to xtty or compilation log.
651     void log_dependency(Klass* witness = nullptr);
652 
653     // Print the current dependency to tty.
654     void print_dependency(outputStream* st, Klass* witness = nullptr, bool verbose = false);
655   };
656   friend class Dependencies::DepStream;
657 
658   static void print_statistics();
659 };
660 
661 
662 class DependencySignature : public ResourceObj {
663  private:
664   int                   _args_count;
665   uintptr_t             _argument_hash[Dependencies::max_arg_count];
666   Dependencies::DepType _type;
667 
668  public:
669   DependencySignature(Dependencies::DepStream& dep) {
670     _args_count = dep.argument_count();
671     _type = dep.type();
672     for (int i = 0; i < _args_count; i++) {
673       _argument_hash[i] = dep.get_identifier(i);
674     }
675   }
676 
677   static bool     equals(DependencySignature const& s1, DependencySignature const& s2);
678   static unsigned hash  (DependencySignature const& s1) { return (unsigned)(s1.arg(0) >> 2); }
679 
680   int args_count()             const { return _args_count; }
681   uintptr_t arg(int idx)       const { return _argument_hash[idx]; }
682   Dependencies::DepType type() const { return _type; }
683 
684 };
685 
686 
687 // Every particular DepChange is a sub-class of this class.
688 class DepChange : public StackObj {
689  public:
690   // What kind of DepChange is this?
691   virtual bool is_klass_change()      const { return false; }
692   virtual bool is_new_klass_change()  const { return false; }
693   virtual bool is_klass_init_change() const { return false; }
694   virtual bool is_call_site_change()  const { return false; }
695 
696   // Subclass casting with assertions.
697   KlassDepChange*    as_klass_change() {
698     assert(is_klass_change(), "bad cast");
699     return (KlassDepChange*) this;
700   }
701   NewKlassDepChange* as_new_klass_change() {
702     assert(is_new_klass_change(), "bad cast");
703     return (NewKlassDepChange*) this;
704   }
705   KlassInitDepChange* as_klass_init_change() {
706     assert(is_klass_init_change(), "bad cast");
707     return (KlassInitDepChange*) this;
708   }
709   CallSiteDepChange* as_call_site_change() {
710     assert(is_call_site_change(), "bad cast");
711     return (CallSiteDepChange*) this;
712   }
713 
714   void print();
715   void print_on(outputStream* st);
716 
717  public:
718   enum ChangeType {
719     NO_CHANGE = 0,              // an uninvolved klass
720     Change_new_type,            // a newly loaded type
721     Change_new_sub,             // a super with a new subtype
722     Change_new_impl,            // an interface with a new implementation
723     CHANGE_LIMIT,
724     Start_Klass = CHANGE_LIMIT  // internal indicator for ContextStream
725   };
726 
727   // Usage:
728   // for (DepChange::ContextStream str(changes); str.next(); ) {
729   //   InstanceKlass* k = str.klass();
730   //   switch (str.change_type()) {
731   //     ...
732   //   }
733   // }
734   class ContextStream : public StackObj {
735    private:
736     DepChange&  _changes;
737     friend class DepChange;
738 
739     // iteration variables:
740     ChangeType     _change_type;
741     InstanceKlass* _klass;
742     Array<InstanceKlass*>* _ti_base;    // i.e., transitive_interfaces
743     int         _ti_index;
744     int         _ti_limit;
745 
746     // start at the beginning:
747     void start();
748 
749    public:
750     ContextStream(DepChange& changes)
751       : _changes(changes)
752     { start(); }
753 
754     ContextStream(DepChange& changes, NoSafepointVerifier& nsv)
755       : _changes(changes)
756       // the nsv argument makes it safe to hold oops like _klass
757     { start(); }
758 
759     bool next();
760 
761     ChangeType change_type()     { return _change_type; }
762     InstanceKlass* klass()       { return _klass; }
763   };
764   friend class DepChange::ContextStream;
765 };
766 
767 
768 // A class hierarchy change coming through the VM (under the Compile_lock).
769 // The change is structured as a single type with any number of supers
770 // and implemented interface types.  Other than the type, any of the
771 // super types can be context types for a relevant dependency, which the
772 // type could invalidate.
773 class KlassDepChange : public DepChange {
774  private:
775   // each change set is rooted in exactly one type (at present):
776   InstanceKlass* _type;
777 
778   void initialize();
779 
780  protected:
781   // notes the type, marks it and all its super-types
782   KlassDepChange(InstanceKlass* type) : _type(type) {
783     initialize();
784   }
785 
786   // cleans up the marks
787   ~KlassDepChange();
788 
789  public:
790   // What kind of DepChange is this?
791   virtual bool is_klass_change() const { return true; }
792 
793   InstanceKlass* type() { return _type; }
794 
795   // involves_context(k) is true if k == _type or any of its super types
796   bool involves_context(Klass* k);
797 };
798 
799 // A class hierarchy change: new type is loaded.
800 class NewKlassDepChange : public KlassDepChange {
801  public:
802   NewKlassDepChange(InstanceKlass* new_type) : KlassDepChange(new_type) {}
803 
804   // What kind of DepChange is this?
805   virtual bool is_new_klass_change() const { return true; }
806 
807   InstanceKlass* new_type() { return type(); }
808 };
809 
810 // Change in initialization state of a loaded class.
811 class KlassInitDepChange : public KlassDepChange {
812  public:
813   KlassInitDepChange(InstanceKlass* type) : KlassDepChange(type) {}
814 
815   // What kind of DepChange is this?
816   virtual bool is_klass_init_change() const { return true; }
817 };
818 
819 // A CallSite has changed its target.
820 class CallSiteDepChange : public DepChange {
821  private:
822   Handle _call_site;
823   Handle _method_handle;
824 
825  public:
826   CallSiteDepChange(Handle call_site, Handle method_handle);
827 
828   // What kind of DepChange is this?
829   virtual bool is_call_site_change() const { return true; }
830 
831   oop call_site()     const { return _call_site();     }
832   oop method_handle() const { return _method_handle(); }
833 };
834 
835 #endif // SHARE_CODE_DEPENDENCIES_HPP
--- EOF ---