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->is_instance_klass(), "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