1 /*
   2  * Copyright (c) 2005, 2015, 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_VM_CODE_DEPENDENCIES_HPP
  26 #define SHARE_VM_CODE_DEPENDENCIES_HPP
  27 
  28 #include "ci/ciCallSite.hpp"
  29 #include "ci/ciKlass.hpp"
  30 #include "ci/ciMethodHandle.hpp"
  31 #include "classfile/systemDictionary.hpp"
  32 #include "code/compressedStream.hpp"
  33 #include "code/nmethod.hpp"
  34 #include "memory/resourceArea.hpp"
  35 #include "utilities/growableArray.hpp"
  36 #include "utilities/hashtable.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 DepChange;
  60 class   KlassDepChange;
  61 class   CallSiteDepChange;
  62 class No_Safepoint_Verifier;
  63 
  64 class Dependencies: public ResourceObj {
  65  public:
  66   // Note: In the comments on dependency types, most uses of the terms
  67   // subtype and supertype are used in a "non-strict" or "inclusive"
  68   // sense, and are starred to remind the reader of this fact.
  69   // Strict uses of the terms use the word "proper".
  70   //
  71   // Specifically, every class is its own subtype* and supertype*.
  72   // (This trick is easier than continually saying things like "Y is a
  73   // subtype of X or X itself".)
  74   //
  75   // Sometimes we write X > Y to mean X is a proper supertype of Y.
  76   // The notation X > {Y, Z} means X has proper subtypes Y, Z.
  77   // The notation X.m > Y means that Y inherits m from X, while
  78   // X.m > Y.m means Y overrides X.m.  A star denotes abstractness,
  79   // as *I > A, meaning (abstract) interface I is a super type of A,
  80   // or A.*m > B.m, meaning B.m implements abstract method A.m.
  81   //
  82   // In this module, the terms "subtype" and "supertype" refer to
  83   // Java-level reference type conversions, as detected by
  84   // "instanceof" and performed by "checkcast" operations.  The method
  85   // Klass::is_subtype_of tests these relations.  Note that "subtype"
  86   // is richer than "subclass" (as tested by Klass::is_subclass_of),
  87   // since it takes account of relations involving interface and array
  88   // types.
  89   //
  90   // To avoid needless complexity, dependencies involving array types
  91   // are not accepted.  If you need to make an assertion about an
  92   // array type, make the assertion about its corresponding element
  93   // types.  Any assertion that might change about an array type can
  94   // be converted to an assertion about its element type.
  95   //
  96   // Most dependencies are evaluated over a "context type" CX, which
  97   // stands for the set Subtypes(CX) of every Java type that is a subtype*
  98   // of CX.  When the system loads a new class or interface N, it is
  99   // responsible for re-evaluating changed dependencies whose context
 100   // type now includes N, that is, all super types of N.
 101   //
 102   enum DepType {
 103     end_marker = 0,
 104 
 105     // An 'evol' dependency simply notes that the contents of the
 106     // method were used.  If it evolves (is replaced), the nmethod
 107     // must be recompiled.  No other dependencies are implied.
 108     evol_method,
 109     FIRST_TYPE = evol_method,
 110 
 111     // A context type CX is a leaf it if has no proper subtype.
 112     leaf_type,
 113 
 114     // An abstract class CX has exactly one concrete subtype CC.
 115     abstract_with_unique_concrete_subtype,
 116 
 117     // The type CX is purely abstract, with no concrete subtype* at all.
 118     abstract_with_no_concrete_subtype,
 119 
 120     // The concrete CX is free of concrete proper subtypes.
 121     concrete_with_no_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,       // one unique concrete method under CX
 140 
 141     // An "exclusive" assertion concerns two methods or subtypes, and
 142     // declares that there are at most two (or perhaps later N>2)
 143     // specific items that jointly satisfy the restriction.
 144     // We list all items explicitly rather than just giving their
 145     // count, for robustness in the face of complex schema changes.
 146 
 147     // A context class CX (which may be either abstract or concrete)
 148     // has two exclusive concrete subtypes* C1, C2 if every concrete
 149     // subtype* of CX is either C1 or C2.  Note that if neither C1 or C2
 150     // are equal to CX, then CX itself must be abstract.  But it is
 151     // also possible (for example) that C1 is CX (a concrete class)
 152     // and C2 is a proper subtype of C1.
 153     abstract_with_exclusive_concrete_subtypes_2,
 154 
 155     // This dependency asserts that MM(CX, M1) is no greater than {M1,M2}.
 156     exclusive_concrete_methods_2,
 157 
 158     // This dependency asserts that no instances of class or it's
 159     // subclasses require finalization registration.
 160     no_finalizable_subclasses,
 161 
 162     // This dependency asserts when the CallSite.target value changed.
 163     call_site_target_value,
 164 
 165     TYPE_LIMIT
 166   };
 167   enum {
 168     LG2_TYPE_LIMIT = 4,  // assert(TYPE_LIMIT <= (1<<LG2_TYPE_LIMIT))
 169 
 170     // handy categorizations of dependency types:
 171     all_types           = ((1 << TYPE_LIMIT) - 1) & ((-1) << FIRST_TYPE),
 172 
 173     non_klass_types     = (1 << call_site_target_value),
 174     klass_types         = all_types & ~non_klass_types,
 175 
 176     non_ctxk_types      = (1 << evol_method) | (1 << call_site_target_value),
 177     implicit_ctxk_types = 0,
 178     explicit_ctxk_types = all_types & ~(non_ctxk_types | implicit_ctxk_types),
 179 
 180     max_arg_count = 3,   // current maximum number of arguments (incl. ctxk)
 181 
 182     // A "context type" is a class or interface that
 183     // provides context for evaluating a dependency.
 184     // When present, it is one of the arguments (dep_context_arg).
 185     //
 186     // If a dependency does not have a context type, there is a
 187     // default context, depending on the type of the dependency.
 188     // This bit signals that a default context has been compressed away.
 189     default_context_type_bit = (1<<LG2_TYPE_LIMIT)
 190   };
 191 
 192   static const char* dep_name(DepType dept);
 193   static int         dep_args(DepType dept);
 194 
 195   static bool is_klass_type(           DepType dept) { return dept_in_mask(dept, klass_types        ); }
 196 
 197   static bool has_explicit_context_arg(DepType dept) { return dept_in_mask(dept, explicit_ctxk_types); }
 198   static bool has_implicit_context_arg(DepType dept) { return dept_in_mask(dept, implicit_ctxk_types); }
 199 
 200   static int           dep_context_arg(DepType dept) { return has_explicit_context_arg(dept) ? 0 : -1; }
 201   static int  dep_implicit_context_arg(DepType dept) { return has_implicit_context_arg(dept) ? 0 : -1; }
 202 
 203   static void check_valid_dependency_type(DepType dept);
 204 
 205 #if INCLUDE_JVMCI
 206   // A Metadata* or object value recorded in an OopRecorder
 207   class DepValue VALUE_OBJ_CLASS_SPEC {
 208    private:
 209     // Unique identifier of the value within the associated OopRecorder that
 210     // encodes both the category of the value (0: invalid, positive: metadata, negative: object)
 211     // and the index within a category specific array (metadata: index + 1, object: -(index + 1))
 212     int _id;
 213 
 214    public:
 215     DepValue() : _id(0) {}
 216     DepValue(OopRecorder* rec, Metadata* metadata, DepValue* candidate = NULL) {
 217       assert(candidate == NULL || candidate->is_metadata(), "oops");
 218       if (candidate != NULL && candidate->as_metadata(rec) == metadata) {
 219         _id = candidate->_id;
 220       } else {
 221         _id = rec->find_index(metadata) + 1;
 222       }
 223     }
 224     DepValue(OopRecorder* rec, jobject obj, DepValue* candidate = NULL) {
 225       assert(candidate == NULL || candidate->is_object(), "oops");
 226       if (candidate != NULL && candidate->as_object(rec) == obj) {
 227         _id = candidate->_id;
 228       } else {
 229         _id = -(rec->find_index(obj) + 1);
 230       }
 231     }
 232 
 233     // Used to sort values in ascending order of index() with metadata values preceding object values
 234     int sort_key() const { return -_id; }
 235 
 236     bool operator == (const DepValue& other) const   { return other._id == _id; }
 237 
 238     bool is_valid() const             { return _id != 0; }
 239     int  index() const                { assert(is_valid(), "oops"); return _id < 0 ? -(_id + 1) : _id - 1; }
 240     bool is_metadata() const          { assert(is_valid(), "oops"); return _id > 0; }
 241     bool is_object() const            { assert(is_valid(), "oops"); return _id < 0; }
 242 
 243     Metadata*  as_metadata(OopRecorder* rec) const    { assert(is_metadata(), "oops"); return rec->metadata_at(index()); }
 244     Klass*     as_klass(OopRecorder* rec) const       { assert(as_metadata(rec)->is_klass(), "oops"); return (Klass*) as_metadata(rec); }
 245     Method*    as_method(OopRecorder* rec) const      { assert(as_metadata(rec)->is_method(), "oops"); return (Method*) as_metadata(rec); }
 246     jobject    as_object(OopRecorder* rec) const      { assert(is_object(), "oops"); return rec->oop_at(index()); }
 247   };
 248 #endif // INCLUDE_JVMCI
 249 
 250  private:
 251   // State for writing a new set of dependencies:
 252   GrowableArray<int>*       _dep_seen;  // (seen[h->ident] & (1<<dept))
 253   GrowableArray<ciBaseObject*>*  _deps[TYPE_LIMIT];
 254 #if INCLUDE_JVMCI
 255   bool _using_dep_values;
 256   GrowableArray<DepValue>*  _dep_values[TYPE_LIMIT];
 257 #endif
 258 
 259   static const char* _dep_name[TYPE_LIMIT];
 260   static int         _dep_args[TYPE_LIMIT];
 261 
 262   static bool dept_in_mask(DepType dept, int mask) {
 263     return (int)dept >= 0 && dept < TYPE_LIMIT && ((1<<dept) & mask) != 0;
 264   }
 265 
 266   bool note_dep_seen(int dept, ciBaseObject* x) {
 267     assert(dept < BitsPerInt, "oob");
 268     int x_id = x->ident();
 269     assert(_dep_seen != NULL, "deps must be writable");
 270     int seen = _dep_seen->at_grow(x_id, 0);
 271     _dep_seen->at_put(x_id, seen | (1<<dept));
 272     // return true if we've already seen dept/x
 273     return (seen & (1<<dept)) != 0;
 274   }
 275 
 276 #if INCLUDE_JVMCI
 277   bool note_dep_seen(int dept, DepValue x) {
 278     assert(dept < BitsPerInt, "oops");
 279     // place metadata deps at even indexes, object deps at odd indexes
 280     int x_id = x.is_metadata() ? x.index() * 2 : (x.index() * 2) + 1;
 281     assert(_dep_seen != NULL, "deps must be writable");
 282     int seen = _dep_seen->at_grow(x_id, 0);
 283     _dep_seen->at_put(x_id, seen | (1<<dept));
 284     // return true if we've already seen dept/x
 285     return (seen & (1<<dept)) != 0;
 286   }
 287 #endif
 288 
 289   bool maybe_merge_ctxk(GrowableArray<ciBaseObject*>* deps,
 290                         int ctxk_i, ciKlass* ctxk);
 291 #if INCLUDE_JVMCI
 292   bool maybe_merge_ctxk(GrowableArray<DepValue>* deps,
 293                         int ctxk_i, DepValue ctxk);
 294 #endif
 295 
 296   void sort_all_deps();
 297   size_t estimate_size_in_bytes();
 298 
 299   // Initialize _deps, etc.
 300   void initialize(ciEnv* env);
 301 
 302   // State for making a new set of dependencies:
 303   OopRecorder* _oop_recorder;
 304 
 305   // Logging support
 306   CompileLog* _log;
 307 
 308   address  _content_bytes;  // everything but the oop references, encoded
 309   size_t   _size_in_bytes;
 310 
 311  public:
 312   // Make a new empty dependencies set.
 313   Dependencies(ciEnv* env) {
 314     initialize(env);
 315   }
 316 #if INCLUDE_JVMCI
 317   Dependencies(Arena* arena, OopRecorder* oop_recorder, CompileLog* log);
 318 #endif
 319 
 320  private:
 321   // Check for a valid context type.
 322   // Enforce the restriction against array types.
 323   static void check_ctxk(ciKlass* ctxk) {
 324     assert(ctxk->is_instance_klass(), "java types only");
 325   }
 326   static void check_ctxk_concrete(ciKlass* ctxk) {
 327     assert(is_concrete_klass(ctxk->as_instance_klass()), "must be concrete");
 328   }
 329   static void check_ctxk_abstract(ciKlass* ctxk) {
 330     check_ctxk(ctxk);
 331     assert(!is_concrete_klass(ctxk->as_instance_klass()), "must be abstract");
 332   }
 333 
 334   void assert_common_1(DepType dept, ciBaseObject* x);
 335   void assert_common_2(DepType dept, ciBaseObject* x0, ciBaseObject* x1);
 336   void assert_common_3(DepType dept, ciKlass* ctxk, ciBaseObject* x1, ciBaseObject* x2);
 337 
 338  public:
 339   // Adding assertions to a new dependency set at compile time:
 340   void assert_evol_method(ciMethod* m);
 341   void assert_leaf_type(ciKlass* ctxk);
 342   void assert_abstract_with_unique_concrete_subtype(ciKlass* ctxk, ciKlass* conck);
 343   void assert_abstract_with_no_concrete_subtype(ciKlass* ctxk);
 344   void assert_concrete_with_no_concrete_subtype(ciKlass* ctxk);
 345   void assert_unique_concrete_method(ciKlass* ctxk, ciMethod* uniqm);
 346   void assert_abstract_with_exclusive_concrete_subtypes(ciKlass* ctxk, ciKlass* k1, ciKlass* k2);
 347   void assert_exclusive_concrete_methods(ciKlass* ctxk, ciMethod* m1, ciMethod* m2);
 348   void assert_has_no_finalizable_subclasses(ciKlass* ctxk);
 349   void assert_call_site_target_value(ciCallSite* call_site, ciMethodHandle* method_handle);
 350 
 351 #if INCLUDE_JVMCI
 352  private:
 353   static void check_ctxk(Klass* ctxk) {
 354     assert(ctxk->oop_is_instance(), "java types only");
 355   }
 356   static void check_ctxk_abstract(Klass* ctxk) {
 357     check_ctxk(ctxk);
 358     assert(ctxk->is_abstract(), "must be abstract");
 359   }
 360   void assert_common_1(DepType dept, DepValue x);
 361   void assert_common_2(DepType dept, DepValue x0, DepValue x1);
 362 
 363  public:
 364   void assert_evol_method(Method* m);
 365   void assert_has_no_finalizable_subclasses(Klass* ctxk);
 366   void assert_leaf_type(Klass* ctxk);
 367   void assert_unique_concrete_method(Klass* ctxk, Method* uniqm);
 368   void assert_abstract_with_unique_concrete_subtype(Klass* ctxk, Klass* conck);
 369   void assert_call_site_target_value(oop callSite, oop methodHandle);
 370 #endif // INCLUDE_JVMCI
 371 
 372   // Define whether a given method or type is concrete.
 373   // These methods define the term "concrete" as used in this module.
 374   // For this module, an "abstract" class is one which is non-concrete.
 375   //
 376   // Future optimizations may allow some classes to remain
 377   // non-concrete until their first instantiation, and allow some
 378   // methods to remain non-concrete until their first invocation.
 379   // In that case, there would be a middle ground between concrete
 380   // and abstract (as defined by the Java language and VM).
 381   static bool is_concrete_klass(Klass* k);    // k is instantiable
 382   static bool is_concrete_method(Method* m, Klass* k);  // m is invocable
 383   static Klass* find_finalizable_subclass(Klass* k);
 384 
 385   // These versions of the concreteness queries work through the CI.
 386   // The CI versions are allowed to skew sometimes from the VM
 387   // (oop-based) versions.  The cost of such a difference is a
 388   // (safely) aborted compilation, or a deoptimization, or a missed
 389   // optimization opportunity.
 390   //
 391   // In order to prevent spurious assertions, query results must
 392   // remain stable within any single ciEnv instance.  (I.e., they must
 393   // not go back into the VM to get their value; they must cache the
 394   // bit in the CI, either eagerly or lazily.)
 395   static bool is_concrete_klass(ciInstanceKlass* k); // k appears instantiable
 396   static bool has_finalizable_subclass(ciInstanceKlass* k);
 397 
 398   // As a general rule, it is OK to compile under the assumption that
 399   // a given type or method is concrete, even if it at some future
 400   // point becomes abstract.  So dependency checking is one-sided, in
 401   // that it permits supposedly concrete classes or methods to turn up
 402   // as really abstract.  (This shouldn't happen, except during class
 403   // evolution, but that's the logic of the checking.)  However, if a
 404   // supposedly abstract class or method suddenly becomes concrete, a
 405   // dependency on it must fail.
 406 
 407   // Checking old assertions at run-time (in the VM only):
 408   static Klass* check_evol_method(Method* m);
 409   static Klass* check_leaf_type(Klass* ctxk);
 410   static Klass* check_abstract_with_unique_concrete_subtype(Klass* ctxk, Klass* conck,
 411                                                               KlassDepChange* changes = NULL);
 412   static Klass* check_abstract_with_no_concrete_subtype(Klass* ctxk,
 413                                                           KlassDepChange* changes = NULL);
 414   static Klass* check_concrete_with_no_concrete_subtype(Klass* ctxk,
 415                                                           KlassDepChange* changes = NULL);
 416   static Klass* check_unique_concrete_method(Klass* ctxk, Method* uniqm,
 417                                                KlassDepChange* changes = NULL);
 418   static Klass* check_abstract_with_exclusive_concrete_subtypes(Klass* ctxk, Klass* k1, Klass* k2,
 419                                                                   KlassDepChange* changes = NULL);
 420   static Klass* check_exclusive_concrete_methods(Klass* ctxk, Method* m1, Method* m2,
 421                                                    KlassDepChange* changes = NULL);
 422   static Klass* check_has_no_finalizable_subclasses(Klass* ctxk, KlassDepChange* changes = NULL);
 423   static Klass* check_call_site_target_value(oop call_site, oop method_handle, CallSiteDepChange* changes = NULL);
 424   // A returned Klass* is NULL if the dependency assertion is still
 425   // valid.  A non-NULL Klass* is a 'witness' to the assertion
 426   // failure, a point in the class hierarchy where the assertion has
 427   // been proven false.  For example, if check_leaf_type returns
 428   // non-NULL, the value is a subtype of the supposed leaf type.  This
 429   // witness value may be useful for logging the dependency failure.
 430   // Note that, when a dependency fails, there may be several possible
 431   // witnesses to the failure.  The value returned from the check_foo
 432   // method is chosen arbitrarily.
 433 
 434   // The 'changes' value, if non-null, requests a limited spot-check
 435   // near the indicated recent changes in the class hierarchy.
 436   // It is used by DepStream::spot_check_dependency_at.
 437 
 438   // Detecting possible new assertions:
 439   static Klass*    find_unique_concrete_subtype(Klass* ctxk);
 440   static Method*   find_unique_concrete_method(Klass* ctxk, Method* m);
 441   static int       find_exclusive_concrete_subtypes(Klass* ctxk, int klen, Klass* k[]);
 442 
 443   // Create the encoding which will be stored in an nmethod.
 444   void encode_content_bytes();
 445 
 446   address content_bytes() {
 447     assert(_content_bytes != NULL, "encode it first");
 448     return _content_bytes;
 449   }
 450   size_t size_in_bytes() {
 451     assert(_content_bytes != NULL, "encode it first");
 452     return _size_in_bytes;
 453   }
 454 
 455   OopRecorder* oop_recorder() { return _oop_recorder; }
 456   CompileLog*  log()          { return _log; }
 457 
 458   void copy_to(nmethod* nm);
 459 
 460   void log_all_dependencies();
 461 
 462   void log_dependency(DepType dept, GrowableArray<ciBaseObject*>* args) {
 463     ResourceMark rm;
 464     int argslen = args->length();
 465     write_dependency_to(log(), dept, args);
 466     guarantee(argslen == args->length(),
 467               "args array cannot grow inside nested ResoureMark scope");
 468   }
 469 
 470   void log_dependency(DepType dept,
 471                       ciBaseObject* x0,
 472                       ciBaseObject* x1 = NULL,
 473                       ciBaseObject* x2 = NULL) {
 474     if (log() == NULL) {
 475       return;
 476     }
 477     ResourceMark rm;
 478     GrowableArray<ciBaseObject*>* ciargs =
 479                 new GrowableArray<ciBaseObject*>(dep_args(dept));
 480     assert (x0 != NULL, "no log x0");
 481     ciargs->push(x0);
 482 
 483     if (x1 != NULL) {
 484       ciargs->push(x1);
 485     }
 486     if (x2 != NULL) {
 487       ciargs->push(x2);
 488     }
 489     assert(ciargs->length() == dep_args(dept), "");
 490     log_dependency(dept, ciargs);
 491   }
 492 
 493   class DepArgument : public ResourceObj {
 494    private:
 495     bool  _is_oop;
 496     bool  _valid;
 497     void* _value;
 498    public:
 499     DepArgument() : _is_oop(false), _value(NULL), _valid(false) {}
 500     DepArgument(oop v): _is_oop(true), _value(v), _valid(true) {}
 501     DepArgument(Metadata* v): _is_oop(false), _value(v), _valid(true) {}
 502 
 503     bool is_null() const               { return _value == NULL; }
 504     bool is_oop() const                { return _is_oop; }
 505     bool is_metadata() const           { return !_is_oop; }
 506     bool is_klass() const              { return is_metadata() && metadata_value()->is_klass(); }
 507     bool is_method() const              { return is_metadata() && metadata_value()->is_method(); }
 508 
 509     oop oop_value() const              { assert(_is_oop && _valid, "must be"); return (oop) _value; }
 510     Metadata* metadata_value() const { assert(!_is_oop && _valid, "must be"); return (Metadata*) _value; }
 511   };
 512 
 513   static void print_dependency(DepType dept,
 514                                GrowableArray<DepArgument>* args,
 515                                Klass* witness = NULL, outputStream* st = tty);
 516 
 517  private:
 518   // helper for encoding common context types as zero:
 519   static ciKlass* ctxk_encoded_as_null(DepType dept, ciBaseObject* x);
 520 
 521   static Klass* ctxk_encoded_as_null(DepType dept, Metadata* x);
 522 
 523   static void write_dependency_to(CompileLog* log,
 524                                   DepType dept,
 525                                   GrowableArray<ciBaseObject*>* args,
 526                                   Klass* witness = NULL);
 527   static void write_dependency_to(CompileLog* log,
 528                                   DepType dept,
 529                                   GrowableArray<DepArgument>* args,
 530                                   Klass* witness = NULL);
 531   static void write_dependency_to(xmlStream* xtty,
 532                                   DepType dept,
 533                                   GrowableArray<DepArgument>* args,
 534                                   Klass* witness = NULL);
 535  public:
 536   // Use this to iterate over an nmethod's dependency set.
 537   // Works on new and old dependency sets.
 538   // Usage:
 539   //
 540   // ;
 541   // Dependencies::DepType dept;
 542   // for (Dependencies::DepStream deps(nm); deps.next(); ) {
 543   //   ...
 544   // }
 545   //
 546   // The caller must be in the VM, since oops are not wrapped in handles.
 547   class DepStream {
 548   private:
 549     nmethod*              _code;   // null if in a compiler thread
 550     Dependencies*         _deps;   // null if not in a compiler thread
 551     CompressedReadStream  _bytes;
 552 #ifdef ASSERT
 553     size_t                _byte_limit;
 554 #endif
 555 
 556     // iteration variables:
 557     DepType               _type;
 558     int                   _xi[max_arg_count+1];
 559 
 560     void initial_asserts(size_t byte_limit) NOT_DEBUG({});
 561 
 562     inline Metadata* recorded_metadata_at(int i);
 563     inline oop recorded_oop_at(int i);
 564 
 565     Klass* check_klass_dependency(KlassDepChange* changes);
 566     Klass* check_call_site_dependency(CallSiteDepChange* changes);
 567 
 568     void trace_and_log_witness(Klass* witness);
 569 
 570   public:
 571     DepStream(Dependencies* deps)
 572       : _deps(deps),
 573         _code(NULL),
 574         _bytes(deps->content_bytes())
 575     {
 576       initial_asserts(deps->size_in_bytes());
 577     }
 578     DepStream(nmethod* code)
 579       : _deps(NULL),
 580         _code(code),
 581         _bytes(code->dependencies_begin())
 582     {
 583       initial_asserts(code->dependencies_size());
 584     }
 585 
 586     bool next();
 587 
 588     DepType type()               { return _type; }
 589     bool is_oop_argument(int i)  { return type() == call_site_target_value; }
 590     uintptr_t get_identifier(int i);
 591 
 592     int argument_count()         { return dep_args(type()); }
 593     int argument_index(int i)    { assert(0 <= i && i < argument_count(), "oob");
 594                                    return _xi[i]; }
 595     Metadata* argument(int i);     // => recorded_oop_at(argument_index(i))
 596     oop argument_oop(int i);         // => recorded_oop_at(argument_index(i))
 597     Klass* context_type();
 598 
 599     bool is_klass_type()         { return Dependencies::is_klass_type(type()); }
 600 
 601     Method* method_argument(int i) {
 602       Metadata* x = argument(i);
 603       assert(x->is_method(), "type");
 604       return (Method*) x;
 605     }
 606     Klass* type_argument(int i) {
 607       Metadata* x = argument(i);
 608       assert(x->is_klass(), "type");
 609       return (Klass*) x;
 610     }
 611 
 612     // The point of the whole exercise:  Is this dep still OK?
 613     Klass* check_dependency() {
 614       Klass* result = check_klass_dependency(NULL);
 615       if (result != NULL)  return result;
 616       return check_call_site_dependency(NULL);
 617     }
 618 
 619     // A lighter version:  Checks only around recent changes in a class
 620     // hierarchy.  (See Universe::flush_dependents_on.)
 621     Klass* spot_check_dependency_at(DepChange& changes);
 622 
 623     // Log the current dependency to xtty or compilation log.
 624     void log_dependency(Klass* witness = NULL);
 625 
 626     // Print the current dependency to tty.
 627     void print_dependency(Klass* witness = NULL, bool verbose = false, outputStream* st = tty);
 628   };
 629   friend class Dependencies::DepStream;
 630 
 631   static void print_statistics() PRODUCT_RETURN;
 632 };
 633 
 634 
 635 class DependencySignature : public ResourceObj {
 636  private:
 637   int                   _args_count;
 638   uintptr_t             _argument_hash[Dependencies::max_arg_count];
 639   Dependencies::DepType _type;
 640 
 641  public:
 642   DependencySignature(Dependencies::DepStream& dep) {
 643     _args_count = dep.argument_count();
 644     _type = dep.type();
 645     for (int i = 0; i < _args_count; i++) {
 646       _argument_hash[i] = dep.get_identifier(i);
 647     }
 648   }
 649 
 650   static bool     equals(DependencySignature const& s1, DependencySignature const& s2);
 651   static unsigned hash  (DependencySignature const& s1) { return s1.arg(0) >> 2; }
 652 
 653   int args_count()             const { return _args_count; }
 654   uintptr_t arg(int idx)       const { return _argument_hash[idx]; }
 655   Dependencies::DepType type() const { return _type; }
 656 
 657 };
 658 
 659 
 660 // Every particular DepChange is a sub-class of this class.
 661 class DepChange : public StackObj {
 662  public:
 663   // What kind of DepChange is this?
 664   virtual bool is_klass_change()     const { return false; }
 665   virtual bool is_call_site_change() const { return false; }
 666 
 667   // Subclass casting with assertions.
 668   KlassDepChange*    as_klass_change() {
 669     assert(is_klass_change(), "bad cast");
 670     return (KlassDepChange*) this;
 671   }
 672   CallSiteDepChange* as_call_site_change() {
 673     assert(is_call_site_change(), "bad cast");
 674     return (CallSiteDepChange*) this;
 675   }
 676 
 677   void print();
 678 
 679  public:
 680   enum ChangeType {
 681     NO_CHANGE = 0,              // an uninvolved klass
 682     Change_new_type,            // a newly loaded type
 683     Change_new_sub,             // a super with a new subtype
 684     Change_new_impl,            // an interface with a new implementation
 685     CHANGE_LIMIT,
 686     Start_Klass = CHANGE_LIMIT  // internal indicator for ContextStream
 687   };
 688 
 689   // Usage:
 690   // for (DepChange::ContextStream str(changes); str.next(); ) {
 691   //   Klass* k = str.klass();
 692   //   switch (str.change_type()) {
 693   //     ...
 694   //   }
 695   // }
 696   class ContextStream : public StackObj {
 697    private:
 698     DepChange&  _changes;
 699     friend class DepChange;
 700 
 701     // iteration variables:
 702     ChangeType  _change_type;
 703     Klass*      _klass;
 704     Array<Klass*>* _ti_base;    // i.e., transitive_interfaces
 705     int         _ti_index;
 706     int         _ti_limit;
 707 
 708     // start at the beginning:
 709     void start();
 710 
 711    public:
 712     ContextStream(DepChange& changes)
 713       : _changes(changes)
 714     { start(); }
 715 
 716     ContextStream(DepChange& changes, No_Safepoint_Verifier& nsv)
 717       : _changes(changes)
 718       // the nsv argument makes it safe to hold oops like _klass
 719     { start(); }
 720 
 721     bool next();
 722 
 723     ChangeType change_type()     { return _change_type; }
 724     Klass*     klass()           { return _klass; }
 725   };
 726   friend class DepChange::ContextStream;
 727 };
 728 
 729 
 730 // A class hierarchy change coming through the VM (under the Compile_lock).
 731 // The change is structured as a single new type with any number of supers
 732 // and implemented interface types.  Other than the new type, any of the
 733 // super types can be context types for a relevant dependency, which the
 734 // new type could invalidate.
 735 class KlassDepChange : public DepChange {
 736  private:
 737   // each change set is rooted in exactly one new type (at present):
 738   KlassHandle _new_type;
 739 
 740   void initialize();
 741 
 742  public:
 743   // notes the new type, marks it and all its super-types
 744   KlassDepChange(KlassHandle new_type)
 745     : _new_type(new_type)
 746   {
 747     initialize();
 748   }
 749 
 750   // cleans up the marks
 751   ~KlassDepChange();
 752 
 753   // What kind of DepChange is this?
 754   virtual bool is_klass_change() const { return true; }
 755 
 756   Klass* new_type() { return _new_type(); }
 757 
 758   // involves_context(k) is true if k is new_type or any of the super types
 759   bool involves_context(Klass* k);
 760 };
 761 
 762 
 763 // A CallSite has changed its target.
 764 class CallSiteDepChange : public DepChange {
 765  private:
 766   Handle _call_site;
 767   Handle _method_handle;
 768 
 769  public:
 770   CallSiteDepChange(Handle call_site, Handle method_handle)
 771     : _call_site(call_site),
 772       _method_handle(method_handle)
 773   {
 774     assert(_call_site()    ->is_a(SystemDictionary::CallSite_klass()),     "must be");
 775     assert(_method_handle.is_null() || _method_handle()->is_a(SystemDictionary::MethodHandle_klass()), "must be");
 776   }
 777 
 778   // What kind of DepChange is this?
 779   virtual bool is_call_site_change() const { return true; }
 780 
 781   oop call_site()     const { return _call_site();     }
 782   oop method_handle() const { return _method_handle(); }
 783 };
 784 
 785 #endif // SHARE_VM_CODE_DEPENDENCIES_HPP
--- EOF ---