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 #include "precompiled.hpp"
  26 #include "ci/ciArrayKlass.hpp"
  27 #include "ci/ciEnv.hpp"
  28 #include "ci/ciKlass.hpp"

  29 #include "ci/ciMethod.hpp"
  30 #include "classfile/javaClasses.inline.hpp"
  31 #include "code/dependencies.hpp"
  32 #include "compiler/compileLog.hpp"
  33 #include "oops/oop.inline.hpp"
  34 #include "runtime/handles.hpp"
  35 #include "runtime/handles.inline.hpp"

  36 #include "runtime/thread.inline.hpp"
  37 #include "utilities/copy.hpp"
  38 
  39 
  40 #ifdef ASSERT
  41 static bool must_be_in_vm() {
  42   Thread* thread = Thread::current();
  43   if (thread->is_Java_thread())
  44     return ((JavaThread*)thread)->thread_state() == _thread_in_vm;
  45   else
  46     return true;  //something like this: thread->is_VM_thread();
  47 }
  48 #endif //ASSERT
  49 








  50 void Dependencies::initialize(ciEnv* env) {
  51   Arena* arena = env->arena();
  52   _oop_recorder = env->oop_recorder();
  53   _log = env->log();
  54   _dep_seen = new(arena) GrowableArray<int>(arena, 500, 0, 0);
  55   DEBUG_ONLY(_deps[end_marker] = NULL);
  56   for (int i = (int)FIRST_TYPE; i < (int)TYPE_LIMIT; i++) {
  57     _deps[i] = new(arena) GrowableArray<ciBaseObject*>(arena, 10, 0, 0);
  58   }
  59   _content_bytes = NULL;
  60   _size_in_bytes = (size_t)-1;
  61 
  62   assert(TYPE_LIMIT <= (1<<LG2_TYPE_LIMIT), "sanity");
  63 }
  64 
  65 void Dependencies::assert_evol_method(ciMethod* m) {
  66   assert_common_1(evol_method, m);
  67 }
  68 
  69 void Dependencies::assert_leaf_type(ciKlass* ctxk) {
  70   if (ctxk->is_array_klass()) {
  71     // As a special case, support this assertion on an array type,
  72     // which reduces to an assertion on its element type.
  73     // Note that this cannot be done with assertions that
  74     // relate to concreteness or abstractness.
  75     ciType* elemt = ctxk->as_array_klass()->base_element_type();
  76     if (!elemt->is_instance_klass())  return;   // Ex:  int[][]
  77     ctxk = elemt->as_instance_klass();
  78     //if (ctxk->is_final())  return;            // Ex:  String[][]
  79   }
  80   check_ctxk(ctxk);
  81   assert_common_1(leaf_type, ctxk);
  82 }
  83 
  84 void Dependencies::assert_abstract_with_unique_concrete_subtype(ciKlass* ctxk, ciKlass* conck) {
  85   check_ctxk_abstract(ctxk);
  86   assert_common_2(abstract_with_unique_concrete_subtype, ctxk, conck);
  87 }
  88 
  89 void Dependencies::assert_abstract_with_no_concrete_subtype(ciKlass* ctxk) {
  90   check_ctxk_abstract(ctxk);
  91   assert_common_1(abstract_with_no_concrete_subtype, ctxk);
  92 }
  93 
  94 void Dependencies::assert_concrete_with_no_concrete_subtype(ciKlass* ctxk) {
  95   check_ctxk_concrete(ctxk);
  96   assert_common_1(concrete_with_no_concrete_subtype, ctxk);
  97 }
  98 
  99 void Dependencies::assert_unique_concrete_method(ciKlass* ctxk, ciMethod* uniqm) {
 100   check_ctxk(ctxk);
 101   assert_common_2(unique_concrete_method, ctxk, uniqm);
 102 }
 103 
 104 void Dependencies::assert_abstract_with_exclusive_concrete_subtypes(ciKlass* ctxk, ciKlass* k1, ciKlass* k2) {
 105   check_ctxk(ctxk);
 106   assert_common_3(abstract_with_exclusive_concrete_subtypes_2, ctxk, k1, k2);
 107 }
 108 
 109 void Dependencies::assert_exclusive_concrete_methods(ciKlass* ctxk, ciMethod* m1, ciMethod* m2) {
 110   check_ctxk(ctxk);
 111   assert_common_3(exclusive_concrete_methods_2, ctxk, m1, m2);
 112 }
 113 
 114 void Dependencies::assert_has_no_finalizable_subclasses(ciKlass* ctxk) {
 115   check_ctxk(ctxk);
 116   assert_common_1(no_finalizable_subclasses, ctxk);
 117 }
 118 
 119 void Dependencies::assert_call_site_target_value(ciCallSite* call_site, ciMethodHandle* method_handle) {
 120   assert_common_2(call_site_target_value, call_site, method_handle);
 121 }
 122 














 123 // Helper function.  If we are adding a new dep. under ctxk2,
 124 // try to find an old dep. under a broader* ctxk1.  If there is
 125 //
 126 bool Dependencies::maybe_merge_ctxk(GrowableArray<ciBaseObject*>* deps,
 127                                     int ctxk_i, ciKlass* ctxk2) {
 128   ciKlass* ctxk1 = deps->at(ctxk_i)->as_metadata()->as_klass();
 129   if (ctxk2->is_subtype_of(ctxk1)) {
 130     return true;  // success, and no need to change
 131   } else if (ctxk1->is_subtype_of(ctxk2)) {
 132     // new context class fully subsumes previous one
 133     deps->at_put(ctxk_i, ctxk2);
 134     return true;
 135   } else {
 136     return false;
 137   }
 138 }
 139 
 140 void Dependencies::assert_common_1(DepType dept, ciBaseObject* x) {
 141   assert(dep_args(dept) == 1, "sanity");
 142   log_dependency(dept, x);
 143   GrowableArray<ciBaseObject*>* deps = _deps[dept];
 144 
 145   // see if the same (or a similar) dep is already recorded
 146   if (note_dep_seen(dept, x)) {
 147     assert(deps->find(x) >= 0, "sanity");
 148   } else {
 149     deps->append(x);
 150   }
 151 }
 152 
 153 void Dependencies::assert_common_2(DepType dept,
 154                                    ciBaseObject* x0, ciBaseObject* x1) {
 155   assert(dep_args(dept) == 2, "sanity");
 156   log_dependency(dept, x0, x1);
 157   GrowableArray<ciBaseObject*>* deps = _deps[dept];
 158 
 159   // see if the same (or a similar) dep is already recorded
 160   bool has_ctxk = has_explicit_context_arg(dept);
 161   if (has_ctxk) {
 162     assert(dep_context_arg(dept) == 0, "sanity");
 163     if (note_dep_seen(dept, x1)) {
 164       // look in this bucket for redundant assertions
 165       const int stride = 2;
 166       for (int i = deps->length(); (i -= stride) >= 0; ) {
 167         ciBaseObject* y1 = deps->at(i+1);
 168         if (x1 == y1) {  // same subject; check the context
 169           if (maybe_merge_ctxk(deps, i+0, x0->as_metadata()->as_klass())) {
 170             return;
 171           }
 172         }
 173       }
 174     }
 175   } else {
 176     if (note_dep_seen(dept, x0) && note_dep_seen(dept, x1)) {
 177       // look in this bucket for redundant assertions
 178       const int stride = 2;
 179       for (int i = deps->length(); (i -= stride) >= 0; ) {
 180         ciBaseObject* y0 = deps->at(i+0);
 181         ciBaseObject* y1 = deps->at(i+1);
 182         if (x0 == y0 && x1 == y1) {
 183           return;
 184         }
 185       }
 186     }
 187   }
 188 
 189   // append the assertion in the correct bucket:
 190   deps->append(x0);
 191   deps->append(x1);
 192 }
 193 
 194 void Dependencies::assert_common_3(DepType dept,
 195                                    ciKlass* ctxk, ciBaseObject* x, ciBaseObject* x2) {
 196   assert(dep_context_arg(dept) == 0, "sanity");
 197   assert(dep_args(dept) == 3, "sanity");
 198   log_dependency(dept, ctxk, x, x2);
 199   GrowableArray<ciBaseObject*>* deps = _deps[dept];
 200 
 201   // try to normalize an unordered pair:
 202   bool swap = false;
 203   switch (dept) {
 204   case abstract_with_exclusive_concrete_subtypes_2:
 205     swap = (x->ident() > x2->ident() && x->as_metadata()->as_klass() != ctxk);
 206     break;
 207   case exclusive_concrete_methods_2:
 208     swap = (x->ident() > x2->ident() && x->as_metadata()->as_method()->holder() != ctxk);
 209     break;
 210   }
 211   if (swap) { ciBaseObject* t = x; x = x2; x2 = t; }
 212 
 213   // see if the same (or a similar) dep is already recorded
 214   if (note_dep_seen(dept, x) && note_dep_seen(dept, x2)) {
 215     // look in this bucket for redundant assertions
 216     const int stride = 3;
 217     for (int i = deps->length(); (i -= stride) >= 0; ) {
 218       ciBaseObject* y  = deps->at(i+1);
 219       ciBaseObject* y2 = deps->at(i+2);
 220       if (x == y && x2 == y2) {  // same subjects; check the context
 221         if (maybe_merge_ctxk(deps, i+0, ctxk)) {
 222           return;
 223         }
 224       }
 225     }
 226   }
 227   // append the assertion in the correct bucket:
 228   deps->append(ctxk);
 229   deps->append(x);
 230   deps->append(x2);
 231 }
 232 
 233 /// Support for encoding dependencies into an nmethod:
 234 
 235 void Dependencies::copy_to(nmethod* nm) {
 236   address beg = nm->dependencies_begin();
 237   address end = nm->dependencies_end();
 238   guarantee(end - beg >= (ptrdiff_t) size_in_bytes(), "bad sizing");
 239   Copy::disjoint_words((HeapWord*) content_bytes(),
 240                        (HeapWord*) beg,
 241                        size_in_bytes() / sizeof(HeapWord));
 242   assert(size_in_bytes() % sizeof(HeapWord) == 0, "copy by words");
 243 }
 244 
 245 static int sort_dep(ciBaseObject** p1, ciBaseObject** p2, int narg) {
 246   for (int i = 0; i < narg; i++) {
 247     int diff = p1[i]->ident() - p2[i]->ident();
 248     if (diff != 0)  return diff;
 249   }
 250   return 0;
 251 }
 252 static int sort_dep_arg_1(ciBaseObject** p1, ciBaseObject** p2)
 253 { return sort_dep(p1, p2, 1); }
 254 static int sort_dep_arg_2(ciBaseObject** p1, ciBaseObject** p2)
 255 { return sort_dep(p1, p2, 2); }
 256 static int sort_dep_arg_3(ciBaseObject** p1, ciBaseObject** p2)
 257 { return sort_dep(p1, p2, 3); }
 258 
 259 void Dependencies::sort_all_deps() {
 260   for (int deptv = (int)FIRST_TYPE; deptv < (int)TYPE_LIMIT; deptv++) {
 261     DepType dept = (DepType)deptv;
 262     GrowableArray<ciBaseObject*>* deps = _deps[dept];
 263     if (deps->length() <= 1)  continue;
 264     switch (dep_args(dept)) {
 265     case 1: deps->sort(sort_dep_arg_1, 1); break;
 266     case 2: deps->sort(sort_dep_arg_2, 2); break;
 267     case 3: deps->sort(sort_dep_arg_3, 3); break;
 268     default: ShouldNotReachHere();
 269     }
 270   }
 271 }
 272 
 273 size_t Dependencies::estimate_size_in_bytes() {
 274   size_t est_size = 100;
 275   for (int deptv = (int)FIRST_TYPE; deptv < (int)TYPE_LIMIT; deptv++) {
 276     DepType dept = (DepType)deptv;
 277     GrowableArray<ciBaseObject*>* deps = _deps[dept];
 278     est_size += deps->length()*2;  // tags and argument(s)
 279   }
 280   return est_size;
 281 }
 282 
 283 ciKlass* Dependencies::ctxk_encoded_as_null(DepType dept, ciBaseObject* x) {
 284   switch (dept) {
 285   case abstract_with_exclusive_concrete_subtypes_2:
 286     return x->as_metadata()->as_klass();
 287   case unique_concrete_method:
 288   case exclusive_concrete_methods_2:
 289     return x->as_metadata()->as_method()->holder();
 290   }
 291   return NULL;  // let NULL be NULL
 292 }
 293 
 294 Klass* Dependencies::ctxk_encoded_as_null(DepType dept, Metadata* x) {
 295   assert(must_be_in_vm(), "raw oops here");
 296   switch (dept) {
 297   case abstract_with_exclusive_concrete_subtypes_2:
 298     assert(x->is_klass(), "sanity");
 299     return (Klass*) x;
 300   case unique_concrete_method:
 301   case exclusive_concrete_methods_2:
 302     assert(x->is_method(), "sanity");
 303     return ((Method*)x)->method_holder();
 304   }
 305   return NULL;  // let NULL be NULL
 306 }
 307 
 308 void Dependencies::encode_content_bytes() {
 309   sort_all_deps();
 310 
 311   // cast is safe, no deps can overflow INT_MAX
 312   CompressedWriteStream bytes((int)estimate_size_in_bytes());
 313 
 314   for (int deptv = (int)FIRST_TYPE; deptv < (int)TYPE_LIMIT; deptv++) {
 315     DepType dept = (DepType)deptv;
 316     GrowableArray<ciBaseObject*>* deps = _deps[dept];
 317     if (deps->length() == 0)  continue;
 318     int stride = dep_args(dept);
 319     int ctxkj  = dep_context_arg(dept);  // -1 if no context arg
 320     assert(stride > 0, "sanity");
 321     for (int i = 0; i < deps->length(); i += stride) {
 322       jbyte code_byte = (jbyte)dept;
 323       int skipj = -1;
 324       if (ctxkj >= 0 && ctxkj+1 < stride) {
 325         ciKlass*  ctxk = deps->at(i+ctxkj+0)->as_metadata()->as_klass();
 326         ciBaseObject* x     = deps->at(i+ctxkj+1);  // following argument
 327         if (ctxk == ctxk_encoded_as_null(dept, x)) {
 328           skipj = ctxkj;  // we win:  maybe one less oop to keep track of
 329           code_byte |= default_context_type_bit;
 330         }
 331       }
 332       bytes.write_byte(code_byte);
 333       for (int j = 0; j < stride; j++) {
 334         if (j == skipj)  continue;
 335         ciBaseObject* v = deps->at(i+j);
 336         int idx;
 337         if (v->is_object()) {
 338           idx = _oop_recorder->find_index(v->as_object()->constant_encoding());
 339         } else {
 340           ciMetadata* meta = v->as_metadata();
 341           idx = _oop_recorder->find_index(meta->constant_encoding());
 342         }
 343         bytes.write_int(idx);
 344       }
 345     }
 346   }
 347 
 348   // write a sentinel byte to mark the end
 349   bytes.write_byte(end_marker);
 350 
 351   // round it out to a word boundary
 352   while (bytes.position() % sizeof(HeapWord) != 0) {
 353     bytes.write_byte(end_marker);
 354   }
 355 
 356   // check whether the dept byte encoding really works
 357   assert((jbyte)default_context_type_bit != 0, "byte overflow");
 358 
 359   _content_bytes = bytes.buffer();
 360   _size_in_bytes = bytes.position();
 361 }
 362 
 363 
 364 const char* Dependencies::_dep_name[TYPE_LIMIT] = {
 365   "end_marker",
 366   "evol_method",
 367   "leaf_type",
 368   "abstract_with_unique_concrete_subtype",
 369   "abstract_with_no_concrete_subtype",
 370   "concrete_with_no_concrete_subtype",
 371   "unique_concrete_method",
 372   "abstract_with_exclusive_concrete_subtypes_2",
 373   "exclusive_concrete_methods_2",
 374   "no_finalizable_subclasses",
 375   "call_site_target_value"


 376 };
 377 
 378 int Dependencies::_dep_args[TYPE_LIMIT] = {
 379   -1,// end_marker
 380   1, // evol_method m
 381   1, // leaf_type ctxk
 382   2, // abstract_with_unique_concrete_subtype ctxk, k
 383   1, // abstract_with_no_concrete_subtype ctxk
 384   1, // concrete_with_no_concrete_subtype ctxk
 385   2, // unique_concrete_method ctxk, m
 386   3, // unique_concrete_subtypes_2 ctxk, k1, k2
 387   3, // unique_concrete_methods_2 ctxk, m1, m2
 388   1, // no_finalizable_subclasses ctxk
 389   2  // call_site_target_value call_site, method_handle


 390 };
 391 
 392 const char* Dependencies::dep_name(Dependencies::DepType dept) {
 393   if (!dept_in_mask(dept, all_types))  return "?bad-dep?";
 394   return _dep_name[dept];
 395 }
 396 
 397 int Dependencies::dep_args(Dependencies::DepType dept) {
 398   if (!dept_in_mask(dept, all_types))  return -1;
 399   return _dep_args[dept];
 400 }
 401 
 402 void Dependencies::check_valid_dependency_type(DepType dept) {
 403   guarantee(FIRST_TYPE <= dept && dept < TYPE_LIMIT, err_msg("invalid dependency type: %d", (int) dept));
 404 }
 405 
 406 // for the sake of the compiler log, print out current dependencies:
 407 void Dependencies::log_all_dependencies() {
 408   if (log() == NULL)  return;
 409   ResourceMark rm;
 410   for (int deptv = (int)FIRST_TYPE; deptv < (int)TYPE_LIMIT; deptv++) {
 411     DepType dept = (DepType)deptv;
 412     GrowableArray<ciBaseObject*>* deps = _deps[dept];
 413     int deplen = deps->length();
 414     if (deplen == 0) {
 415       continue;
 416     }
 417     int stride = dep_args(dept);
 418     GrowableArray<ciBaseObject*>* ciargs = new GrowableArray<ciBaseObject*>(stride);
 419     for (int i = 0; i < deps->length(); i += stride) {
 420       for (int j = 0; j < stride; j++) {
 421         // flush out the identities before printing
 422         ciargs->push(deps->at(i+j));
 423       }
 424       write_dependency_to(log(), dept, ciargs);
 425       ciargs->clear();
 426     }
 427     guarantee(deplen == deps->length(), "deps array cannot grow inside nested ResoureMark scope");
 428   }
 429 }
 430 
 431 void Dependencies::write_dependency_to(CompileLog* log,
 432                                        DepType dept,
 433                                        GrowableArray<DepArgument>* args,
 434                                        Klass* witness) {
 435   if (log == NULL) {
 436     return;
 437   }
 438   ResourceMark rm;
 439   ciEnv* env = ciEnv::current();
 440   GrowableArray<ciBaseObject*>* ciargs = new GrowableArray<ciBaseObject*>(args->length());
 441   for (GrowableArrayIterator<DepArgument> it = args->begin(); it != args->end(); ++it) {
 442     DepArgument arg = *it;
 443     if (arg.is_oop()) {
 444       ciargs->push(env->get_object(arg.oop_value()));
 445     } else {
 446       ciargs->push(env->get_metadata(arg.metadata_value()));
 447     }
 448   }
 449   int argslen = ciargs->length();
 450   Dependencies::write_dependency_to(log, dept, ciargs, witness);
 451   guarantee(argslen == ciargs->length(), "ciargs array cannot grow inside nested ResoureMark scope");
 452 }
 453 
 454 void Dependencies::write_dependency_to(CompileLog* log,
 455                                        DepType dept,
 456                                        GrowableArray<ciBaseObject*>* args,
 457                                        Klass* witness) {
 458   if (log == NULL) {
 459     return;
 460   }
 461   ResourceMark rm;
 462   GrowableArray<int>* argids = new GrowableArray<int>(args->length());
 463   for (GrowableArrayIterator<ciBaseObject*> it = args->begin(); it != args->end(); ++it) {
 464     ciBaseObject* obj = *it;
 465     if (obj->is_object()) {
 466       argids->push(log->identify(obj->as_object()));
 467     } else {
 468       argids->push(log->identify(obj->as_metadata()));
 469     }
 470   }
 471   if (witness != NULL) {
 472     log->begin_elem("dependency_failed");
 473   } else {
 474     log->begin_elem("dependency");
 475   }
 476   log->print(" type='%s'", dep_name(dept));
 477   const int ctxkj = dep_context_arg(dept);  // -1 if no context arg
 478   if (ctxkj >= 0 && ctxkj < argids->length()) {
 479     log->print(" ctxk='%d'", argids->at(ctxkj));
 480   }
 481   // write remaining arguments, if any.
 482   for (int j = 0; j < argids->length(); j++) {
 483     if (j == ctxkj)  continue;  // already logged
 484     if (j == 1) {
 485       log->print(  " x='%d'",    argids->at(j));
 486     } else {
 487       log->print(" x%d='%d'", j, argids->at(j));
 488     }
 489   }
 490   if (witness != NULL) {
 491     log->object("witness", witness);
 492     log->stamp();
 493   }
 494   log->end_elem();
 495 }
 496 
 497 void Dependencies::write_dependency_to(xmlStream* xtty,
 498                                        DepType dept,
 499                                        GrowableArray<DepArgument>* args,
 500                                        Klass* witness) {
 501   if (xtty == NULL) {
 502     return;
 503   }
 504   ResourceMark rm;
 505   ttyLocker ttyl;
 506   int ctxkj = dep_context_arg(dept);  // -1 if no context arg
 507   if (witness != NULL) {
 508     xtty->begin_elem("dependency_failed");
 509   } else {
 510     xtty->begin_elem("dependency");
 511   }
 512   xtty->print(" type='%s'", dep_name(dept));
 513   if (ctxkj >= 0) {
 514     xtty->object("ctxk", args->at(ctxkj).metadata_value());
 515   }
 516   // write remaining arguments, if any.
 517   for (int j = 0; j < args->length(); j++) {
 518     if (j == ctxkj)  continue;  // already logged
 519     DepArgument arg = args->at(j);
 520     if (j == 1) {
 521       if (arg.is_oop()) {
 522         xtty->object("x", arg.oop_value());
 523       } else {
 524         xtty->object("x", arg.metadata_value());
 525       }
 526     } else {
 527       char xn[10]; sprintf(xn, "x%d", j);
 528       if (arg.is_oop()) {
 529         xtty->object(xn, arg.oop_value());
 530       } else {
 531         xtty->object(xn, arg.metadata_value());
 532       }
 533     }
 534   }
 535   if (witness != NULL) {
 536     xtty->object("witness", witness);
 537     xtty->stamp();
 538   }
 539   xtty->end_elem();
 540 }
 541 
 542 void Dependencies::print_dependency(DepType dept, GrowableArray<DepArgument>* args,
 543                                     Klass* witness) {
 544   ResourceMark rm;
 545   ttyLocker ttyl;   // keep the following output all in one block
 546   tty->print_cr("%s of type %s",
 547                 (witness == NULL)? "Dependency": "Failed dependency",
 548                 dep_name(dept));
 549   // print arguments
 550   int ctxkj = dep_context_arg(dept);  // -1 if no context arg
 551   for (int j = 0; j < args->length(); j++) {
 552     DepArgument arg = args->at(j);
 553     bool put_star = false;
 554     if (arg.is_null())  continue;
 555     const char* what;
 556     if (j == ctxkj) {
 557       assert(arg.is_metadata(), "must be");
 558       what = "context";
 559       put_star = !Dependencies::is_concrete_klass((Klass*)arg.metadata_value());
 560     } else if (arg.is_method()) {
 561       what = "method ";
 562       put_star = !Dependencies::is_concrete_method((Method*)arg.metadata_value(), NULL);
 563     } else if (arg.is_klass()) {
 564       what = "class  ";
 565     } else {
 566       what = "object ";
 567     }
 568     tty->print("  %s = %s", what, (put_star? "*": ""));
 569     if (arg.is_klass()) {
 570       tty->print("%s", ((Klass*)arg.metadata_value())->external_name());
 571     } else if (arg.is_method()) {
 572       ((Method*)arg.metadata_value())->print_value();
 573     } else if (arg.is_oop()) {
 574       arg.oop_value()->print_value_on(tty);
 575     } else {
 576       ShouldNotReachHere(); // Provide impl for this type.
 577     }
 578 
 579     tty->cr();
 580   }
 581   if (witness != NULL) {
 582     bool put_star = !Dependencies::is_concrete_klass(witness);
 583     tty->print_cr("  witness = %s%s",
 584                   (put_star? "*": ""),
 585                   witness->external_name());
 586   }
 587 }
 588 
 589 void Dependencies::DepStream::log_dependency(Klass* witness) {
 590   if (_deps == NULL && xtty == NULL)  return;  // fast cutout for runtime
 591   ResourceMark rm;
 592   const int nargs = argument_count();
 593   GrowableArray<DepArgument>* args = new GrowableArray<DepArgument>(nargs);
 594   for (int j = 0; j < nargs; j++) {
 595     if (is_oop_argument(j)) {
 596       args->push(argument_oop(j));
 597     } else {
 598       args->push(argument(j));
 599     }
 600   }
 601   int argslen = args->length();
 602   if (_deps != NULL && _deps->log() != NULL) {
 603     Dependencies::write_dependency_to(_deps->log(), type(), args, witness);
 604   } else {
 605     Dependencies::write_dependency_to(xtty, type(), args, witness);
 606   }
 607   guarantee(argslen == args->length(), "args array cannot grow inside nested ResoureMark scope");
 608 }
 609 
 610 void Dependencies::DepStream::print_dependency(Klass* witness, bool verbose) {
 611   ResourceMark rm;
 612   int nargs = argument_count();
 613   GrowableArray<DepArgument>* args = new GrowableArray<DepArgument>(nargs);
 614   for (int j = 0; j < nargs; j++) {
 615     if (is_oop_argument(j)) {
 616       args->push(argument_oop(j));
 617     } else {
 618       args->push(argument(j));
 619     }
 620   }
 621   int argslen = args->length();
 622   Dependencies::print_dependency(type(), args, witness);
 623   if (verbose) {
 624     if (_code != NULL) {
 625       tty->print("  code: ");
 626       _code->print_value_on(tty);
 627       tty->cr();
 628     }
 629   }
 630   guarantee(argslen == args->length(), "args array cannot grow inside nested ResoureMark scope");
 631 }
 632 
 633 
 634 /// Dependency stream support (decodes dependencies from an nmethod):
 635 
 636 #ifdef ASSERT
 637 void Dependencies::DepStream::initial_asserts(size_t byte_limit) {
 638   assert(must_be_in_vm(), "raw oops here");
 639   _byte_limit = byte_limit;
 640   _type       = (DepType)(end_marker-1);  // defeat "already at end" assert
 641   assert((_code!=NULL) + (_deps!=NULL) == 1, "one or t'other");
 642 }
 643 #endif //ASSERT
 644 
 645 bool Dependencies::DepStream::next() {
 646   assert(_type != end_marker, "already at end");
 647   if (_bytes.position() == 0 && _code != NULL
 648       && _code->dependencies_size() == 0) {
 649     // Method has no dependencies at all.
 650     return false;
 651   }
 652   int code_byte = (_bytes.read_byte() & 0xFF);
 653   if (code_byte == end_marker) {
 654     DEBUG_ONLY(_type = end_marker);
 655     return false;
 656   } else {
 657     int ctxk_bit = (code_byte & Dependencies::default_context_type_bit);
 658     code_byte -= ctxk_bit;
 659     DepType dept = (DepType)code_byte;
 660     _type = dept;
 661     Dependencies::check_valid_dependency_type(dept);
 662     int stride = _dep_args[dept];
 663     assert(stride == dep_args(dept), "sanity");
 664     int skipj = -1;
 665     if (ctxk_bit != 0) {
 666       skipj = 0;  // currently the only context argument is at zero
 667       assert(skipj == dep_context_arg(dept), "zero arg always ctxk");
 668     }
 669     for (int j = 0; j < stride; j++) {
 670       _xi[j] = (j == skipj)? 0: _bytes.read_int();
 671     }
 672     DEBUG_ONLY(_xi[stride] = -1);   // help detect overruns
 673     return true;
 674   }
 675 }
 676 
 677 inline Metadata* Dependencies::DepStream::recorded_metadata_at(int i) {
 678   Metadata* o = NULL;
 679   if (_code != NULL) {
 680     o = _code->metadata_at(i);
 681   } else {
 682     o = _deps->oop_recorder()->metadata_at(i);
 683   }
 684   return o;
 685 }
 686 
 687 inline oop Dependencies::DepStream::recorded_oop_at(int i) {
 688   return (_code != NULL)
 689          ? _code->oop_at(i)
 690     : JNIHandles::resolve(_deps->oop_recorder()->oop_at(i));
 691 }
 692 
 693 Metadata* Dependencies::DepStream::argument(int i) {
 694   Metadata* result = recorded_metadata_at(argument_index(i));
 695 
 696   if (result == NULL) { // Explicit context argument can be compressed
 697     int ctxkj = dep_context_arg(type());  // -1 if no explicit context arg
 698     if (ctxkj >= 0 && i == ctxkj && ctxkj+1 < argument_count()) {
 699       result = ctxk_encoded_as_null(type(), argument(ctxkj+1));
 700     }
 701   }
 702 
 703   assert(result == NULL || result->is_klass() || result->is_method(), "must be");
 704   return result;
 705 }
 706 
 707 /**
 708  * Returns a unique identifier for each dependency argument.
 709  */
 710 uintptr_t Dependencies::DepStream::get_identifier(int i) {
 711   if (is_oop_argument(i)) {
 712     return (uintptr_t)(oopDesc*)argument_oop(i);
 713   } else {
 714     return (uintptr_t)argument(i);
 715   }
 716 }
 717 
 718 oop Dependencies::DepStream::argument_oop(int i) {
 719   oop result = recorded_oop_at(argument_index(i));
 720   assert(result == NULL || result->is_oop(), "must be");
 721   return result;
 722 }
 723 
 724 Klass* Dependencies::DepStream::context_type() {
 725   assert(must_be_in_vm(), "raw oops here");
 726 
 727   // Most dependencies have an explicit context type argument.
 728   {
 729     int ctxkj = dep_context_arg(type());  // -1 if no explicit context arg
 730     if (ctxkj >= 0) {
 731       Metadata* k = argument(ctxkj);
 732       assert(k != NULL && k->is_klass(), "type check");
 733       return (Klass*)k;
 734     }
 735   }
 736 
 737   // Some dependencies are using the klass of the first object
 738   // argument as implicit context type.
 739   {
 740     int ctxkj = dep_implicit_context_arg(type());
 741     if (ctxkj >= 0) {
 742       Klass* k = argument_oop(ctxkj)->klass();
 743       assert(k != NULL && k->is_klass(), "type check");
 744       return (Klass*) k;
 745     }
 746   }
 747 
 748   // And some dependencies don't have a context type at all,
 749   // e.g. evol_method.
 750   return NULL;
 751 }
 752 
 753 // ----------------- DependencySignature --------------------------------------
 754 bool DependencySignature::equals(DependencySignature const& s1, DependencySignature const& s2) {
 755   if ((s1.type() != s2.type()) || (s1.args_count() != s2.args_count())) {
 756     return false;
 757   }
 758 
 759   for (int i = 0; i < s1.args_count(); i++) {
 760     if (s1.arg(i) != s2.arg(i)) {
 761       return false;
 762     }
 763   }
 764   return true;
 765 }
 766 
 767 /// Checking dependencies:
 768 
 769 // This hierarchy walker inspects subtypes of a given type,
 770 // trying to find a "bad" class which breaks a dependency.
 771 // Such a class is called a "witness" to the broken dependency.
 772 // While searching around, we ignore "participants", which
 773 // are already known to the dependency.
 774 class ClassHierarchyWalker {
 775  public:
 776   enum { PARTICIPANT_LIMIT = 3 };
 777 
 778  private:
 779   // optional method descriptor to check for:
 780   Symbol* _name;
 781   Symbol* _signature;
 782 
 783   // special classes which are not allowed to be witnesses:
 784   Klass*    _participants[PARTICIPANT_LIMIT+1];
 785   int       _num_participants;
 786 
 787   // cache of method lookups
 788   Method* _found_methods[PARTICIPANT_LIMIT+1];
 789 
 790   // if non-zero, tells how many witnesses to convert to participants
 791   int       _record_witnesses;
 792 
 793   void initialize(Klass* participant) {
 794     _record_witnesses = 0;
 795     _participants[0]  = participant;
 796     _found_methods[0] = NULL;
 797     _num_participants = 0;
 798     if (participant != NULL) {
 799       // Terminating NULL.
 800       _participants[1] = NULL;
 801       _found_methods[1] = NULL;
 802       _num_participants = 1;
 803     }
 804   }
 805 
 806   void initialize_from_method(Method* m) {
 807     assert(m != NULL && m->is_method(), "sanity");
 808     _name      = m->name();
 809     _signature = m->signature();
 810   }
 811 
 812  public:
 813   // The walker is initialized to recognize certain methods and/or types
 814   // as friendly participants.
 815   ClassHierarchyWalker(Klass* participant, Method* m) {
 816     initialize_from_method(m);
 817     initialize(participant);
 818   }
 819   ClassHierarchyWalker(Method* m) {
 820     initialize_from_method(m);
 821     initialize(NULL);
 822   }
 823   ClassHierarchyWalker(Klass* participant = NULL) {
 824     _name      = NULL;
 825     _signature = NULL;
 826     initialize(participant);
 827   }
 828 
 829   // This is common code for two searches:  One for concrete subtypes,
 830   // the other for concrete method implementations and overrides.
 831   bool doing_subtype_search() {
 832     return _name == NULL;
 833   }
 834 
 835   int num_participants() { return _num_participants; }
 836   Klass* participant(int n) {
 837     assert((uint)n <= (uint)_num_participants, "oob");
 838     return _participants[n];
 839   }
 840 
 841   // Note:  If n==num_participants, returns NULL.
 842   Method* found_method(int n) {
 843     assert((uint)n <= (uint)_num_participants, "oob");
 844     Method* fm = _found_methods[n];
 845     assert(n == _num_participants || fm != NULL, "proper usage");
 846     if (fm != NULL && fm->method_holder() != _participants[n]) {
 847       // Default methods from interfaces can be added to classes. In
 848       // that case the holder of the method is not the class but the
 849       // interface where it's defined.
 850       assert(fm->is_default_method(), "sanity");
 851       return NULL;
 852     }
 853     return fm;
 854   }
 855 
 856 #ifdef ASSERT
 857   // Assert that m is inherited into ctxk, without intervening overrides.
 858   // (May return true even if this is not true, in corner cases where we punt.)
 859   bool check_method_context(Klass* ctxk, Method* m) {
 860     if (m->method_holder() == ctxk)
 861       return true;  // Quick win.
 862     if (m->is_private())
 863       return false; // Quick lose.  Should not happen.
 864     if (!(m->is_public() || m->is_protected()))
 865       // The override story is complex when packages get involved.
 866       return true;  // Must punt the assertion to true.
 867     Klass* k = ctxk;
 868     Method* lm = k->lookup_method(m->name(), m->signature());
 869     if (lm == NULL && k->oop_is_instance()) {
 870       // It might be an interface method
 871         lm = ((InstanceKlass*)k)->lookup_method_in_ordered_interfaces(m->name(),
 872                                                                 m->signature());
 873     }
 874     if (lm == m)
 875       // Method m is inherited into ctxk.
 876       return true;
 877     if (lm != NULL) {
 878       if (!(lm->is_public() || lm->is_protected())) {
 879         // Method is [package-]private, so the override story is complex.
 880         return true;  // Must punt the assertion to true.
 881       }
 882       if (lm->is_static()) {
 883         // Static methods don't override non-static so punt
 884         return true;
 885       }
 886       if (   !Dependencies::is_concrete_method(lm, k)
 887           && !Dependencies::is_concrete_method(m, ctxk)
 888           && lm->method_holder()->is_subtype_of(m->method_holder()))
 889         // Method m is overridden by lm, but both are non-concrete.
 890         return true;
 891     }
 892     ResourceMark rm;
 893     tty->print_cr("Dependency method not found in the associated context:");
 894     tty->print_cr("  context = %s", ctxk->external_name());
 895     tty->print(   "  method = "); m->print_short_name(tty); tty->cr();
 896     if (lm != NULL) {
 897       tty->print( "  found = "); lm->print_short_name(tty); tty->cr();
 898     }
 899     return false;
 900   }
 901 #endif
 902 
 903   void add_participant(Klass* participant) {
 904     assert(_num_participants + _record_witnesses < PARTICIPANT_LIMIT, "oob");
 905     int np = _num_participants++;
 906     _participants[np] = participant;
 907     _participants[np+1] = NULL;
 908     _found_methods[np+1] = NULL;
 909   }
 910 
 911   void record_witnesses(int add) {
 912     if (add > PARTICIPANT_LIMIT)  add = PARTICIPANT_LIMIT;
 913     assert(_num_participants + add < PARTICIPANT_LIMIT, "oob");
 914     _record_witnesses = add;
 915   }
 916 
 917   bool is_witness(Klass* k) {
 918     if (doing_subtype_search()) {
 919       return Dependencies::is_concrete_klass(k);
 920     } else if (!k->oop_is_instance()) {
 921       return false; // no methods to find in an array type
 922     } else {
 923       // Search class hierarchy first.
 924       Method* m = InstanceKlass::cast(k)->find_instance_method(_name, _signature);
 925       if (!Dependencies::is_concrete_method(m, k)) {
 926         // Check interface defaults also, if any exist.
 927         Array<Method*>* default_methods = InstanceKlass::cast(k)->default_methods();
 928         if (default_methods == NULL)
 929             return false;
 930         m = InstanceKlass::cast(k)->find_method(default_methods, _name, _signature);
 931         if (!Dependencies::is_concrete_method(m, NULL))
 932             return false;
 933       }
 934       _found_methods[_num_participants] = m;
 935       // Note:  If add_participant(k) is called,
 936       // the method m will already be memoized for it.
 937       return true;
 938     }
 939   }
 940 
 941   bool is_participant(Klass* k) {
 942     if (k == _participants[0]) {
 943       return true;
 944     } else if (_num_participants <= 1) {
 945       return false;
 946     } else {
 947       return in_list(k, &_participants[1]);
 948     }
 949   }
 950   bool ignore_witness(Klass* witness) {
 951     if (_record_witnesses == 0) {
 952       return false;
 953     } else {
 954       --_record_witnesses;
 955       add_participant(witness);
 956       return true;
 957     }
 958   }
 959   static bool in_list(Klass* x, Klass** list) {
 960     for (int i = 0; ; i++) {
 961       Klass* y = list[i];
 962       if (y == NULL)  break;
 963       if (y == x)  return true;
 964     }
 965     return false;  // not in list
 966   }
 967 
 968  private:
 969   // the actual search method:
 970   Klass* find_witness_anywhere(Klass* context_type,
 971                                  bool participants_hide_witnesses,
 972                                  bool top_level_call = true);
 973   // the spot-checking version:
 974   Klass* find_witness_in(KlassDepChange& changes,
 975                          Klass* context_type,
 976                            bool participants_hide_witnesses);
 977  public:
 978   Klass* find_witness_subtype(Klass* context_type, KlassDepChange* changes = NULL) {
 979     assert(doing_subtype_search(), "must set up a subtype search");
 980     // When looking for unexpected concrete types,
 981     // do not look beneath expected ones.
 982     const bool participants_hide_witnesses = true;
 983     // CX > CC > C' is OK, even if C' is new.
 984     // CX > { CC,  C' } is not OK if C' is new, and C' is the witness.
 985     if (changes != NULL) {
 986       return find_witness_in(*changes, context_type, participants_hide_witnesses);
 987     } else {
 988       return find_witness_anywhere(context_type, participants_hide_witnesses);
 989     }
 990   }
 991   Klass* find_witness_definer(Klass* context_type, KlassDepChange* changes = NULL) {
 992     assert(!doing_subtype_search(), "must set up a method definer search");
 993     // When looking for unexpected concrete methods,
 994     // look beneath expected ones, to see if there are overrides.
 995     const bool participants_hide_witnesses = true;
 996     // CX.m > CC.m > C'.m is not OK, if C'.m is new, and C' is the witness.
 997     if (changes != NULL) {
 998       return find_witness_in(*changes, context_type, !participants_hide_witnesses);
 999     } else {
1000       return find_witness_anywhere(context_type, !participants_hide_witnesses);
1001     }
1002   }
1003 };
1004 
1005 #ifndef PRODUCT
1006 static int deps_find_witness_calls = 0;
1007 static int deps_find_witness_steps = 0;
1008 static int deps_find_witness_recursions = 0;
1009 static int deps_find_witness_singles = 0;
1010 static int deps_find_witness_print = 0; // set to -1 to force a final print
1011 static bool count_find_witness_calls() {
1012   if (TraceDependencies || LogCompilation) {
1013     int pcount = deps_find_witness_print + 1;
1014     bool final_stats      = (pcount == 0);
1015     bool initial_call     = (pcount == 1);
1016     bool occasional_print = ((pcount & ((1<<10) - 1)) == 0);
1017     if (pcount < 0)  pcount = 1; // crude overflow protection
1018     deps_find_witness_print = pcount;
1019     if (VerifyDependencies && initial_call) {
1020       tty->print_cr("Warning:  TraceDependencies results may be inflated by VerifyDependencies");
1021     }
1022     if (occasional_print || final_stats) {
1023       // Every now and then dump a little info about dependency searching.
1024       if (xtty != NULL) {
1025        ttyLocker ttyl;
1026        xtty->elem("deps_find_witness calls='%d' steps='%d' recursions='%d' singles='%d'",
1027                    deps_find_witness_calls,
1028                    deps_find_witness_steps,
1029                    deps_find_witness_recursions,
1030                    deps_find_witness_singles);
1031       }
1032       if (final_stats || (TraceDependencies && WizardMode)) {
1033         ttyLocker ttyl;
1034         tty->print_cr("Dependency check (find_witness) "
1035                       "calls=%d, steps=%d (avg=%.1f), recursions=%d, singles=%d",
1036                       deps_find_witness_calls,
1037                       deps_find_witness_steps,
1038                       (double)deps_find_witness_steps / deps_find_witness_calls,
1039                       deps_find_witness_recursions,
1040                       deps_find_witness_singles);
1041       }
1042     }
1043     return true;
1044   }
1045   return false;
1046 }
1047 #else
1048 #define count_find_witness_calls() (0)
1049 #endif //PRODUCT
1050 
1051 
1052 Klass* ClassHierarchyWalker::find_witness_in(KlassDepChange& changes,
1053                                                Klass* context_type,
1054                                                bool participants_hide_witnesses) {
1055   assert(changes.involves_context(context_type), "irrelevant dependency");
1056   Klass* new_type = changes.new_type();
1057 
1058   (void)count_find_witness_calls();
1059   NOT_PRODUCT(deps_find_witness_singles++);
1060 
1061   // Current thread must be in VM (not native mode, as in CI):
1062   assert(must_be_in_vm(), "raw oops here");
1063   // Must not move the class hierarchy during this check:
1064   assert_locked_or_safepoint(Compile_lock);
1065 
1066   int nof_impls = InstanceKlass::cast(context_type)->nof_implementors();
1067   if (nof_impls > 1) {
1068     // Avoid this case: *I.m > { A.m, C }; B.m > C
1069     // %%% Until this is fixed more systematically, bail out.
1070     // See corresponding comment in find_witness_anywhere.
1071     return context_type;
1072   }
1073 
1074   assert(!is_participant(new_type), "only old classes are participants");
1075   if (participants_hide_witnesses) {
1076     // If the new type is a subtype of a participant, we are done.
1077     for (int i = 0; i < num_participants(); i++) {
1078       Klass* part = participant(i);
1079       if (part == NULL)  continue;
1080       assert(changes.involves_context(part) == new_type->is_subtype_of(part),
1081              "correct marking of participants, b/c new_type is unique");
1082       if (changes.involves_context(part)) {
1083         // new guy is protected from this check by previous participant
1084         return NULL;
1085       }
1086     }
1087   }
1088 
1089   if (is_witness(new_type) &&
1090       !ignore_witness(new_type)) {
1091     return new_type;
1092   }
1093 
1094   return NULL;
1095 }
1096 
1097 
1098 // Walk hierarchy under a context type, looking for unexpected types.
1099 // Do not report participant types, and recursively walk beneath
1100 // them only if participants_hide_witnesses is false.
1101 // If top_level_call is false, skip testing the context type,
1102 // because the caller has already considered it.
1103 Klass* ClassHierarchyWalker::find_witness_anywhere(Klass* context_type,
1104                                                      bool participants_hide_witnesses,
1105                                                      bool top_level_call) {
1106   // Current thread must be in VM (not native mode, as in CI):
1107   assert(must_be_in_vm(), "raw oops here");
1108   // Must not move the class hierarchy during this check:
1109   assert_locked_or_safepoint(Compile_lock);
1110 
1111   bool do_counts = count_find_witness_calls();
1112 
1113   // Check the root of the sub-hierarchy first.
1114   if (top_level_call) {
1115     if (do_counts) {
1116       NOT_PRODUCT(deps_find_witness_calls++);
1117       NOT_PRODUCT(deps_find_witness_steps++);
1118     }
1119     if (is_participant(context_type)) {
1120       if (participants_hide_witnesses)  return NULL;
1121       // else fall through to search loop...
1122     } else if (is_witness(context_type) && !ignore_witness(context_type)) {
1123       // The context is an abstract class or interface, to start with.
1124       return context_type;
1125     }
1126   }
1127 
1128   // Now we must check each implementor and each subclass.
1129   // Use a short worklist to avoid blowing the stack.
1130   // Each worklist entry is a *chain* of subklass siblings to process.
1131   const int CHAINMAX = 100;  // >= 1 + InstanceKlass::implementors_limit
1132   Klass* chains[CHAINMAX];
1133   int    chaini = 0;  // index into worklist
1134   Klass* chain;       // scratch variable
1135 #define ADD_SUBCLASS_CHAIN(k)                     {  \
1136     assert(chaini < CHAINMAX, "oob");                \
1137     chain = k->subklass();                           \
1138     if (chain != NULL)  chains[chaini++] = chain;    }
1139 
1140   // Look for non-abstract subclasses.
1141   // (Note:  Interfaces do not have subclasses.)
1142   ADD_SUBCLASS_CHAIN(context_type);
1143 
1144   // If it is an interface, search its direct implementors.
1145   // (Their subclasses are additional indirect implementors.
1146   // See InstanceKlass::add_implementor.)
1147   // (Note:  nof_implementors is always zero for non-interfaces.)
1148   if (top_level_call) {
1149     int nof_impls = InstanceKlass::cast(context_type)->nof_implementors();
1150     if (nof_impls > 1) {
1151       // Avoid this case: *I.m > { A.m, C }; B.m > C
1152       // Here, I.m has 2 concrete implementations, but m appears unique
1153       // as A.m, because the search misses B.m when checking C.
1154       // The inherited method B.m was getting missed by the walker
1155       // when interface 'I' was the starting point.
1156       // %%% Until this is fixed more systematically, bail out.
1157       // (Old CHA had the same limitation.)
1158       return context_type;
1159     }
1160     if (nof_impls > 0) {
1161       Klass* impl = InstanceKlass::cast(context_type)->implementor();
1162       assert(impl != NULL, "just checking");
1163       // If impl is the same as the context_type, then more than one
1164       // implementor has seen. No exact info in this case.
1165       if (impl == context_type) {
1166         return context_type;  // report an inexact witness to this sad affair
1167       }
1168       if (do_counts)
1169         { NOT_PRODUCT(deps_find_witness_steps++); }
1170       if (is_participant(impl)) {
1171         if (!participants_hide_witnesses) {
1172           ADD_SUBCLASS_CHAIN(impl);
1173         }
1174       } else if (is_witness(impl) && !ignore_witness(impl)) {
1175         return impl;
1176       } else {
1177         ADD_SUBCLASS_CHAIN(impl);
1178       }
1179     }
1180   }
1181 
1182   // Recursively process each non-trivial sibling chain.
1183   while (chaini > 0) {
1184     Klass* chain = chains[--chaini];
1185     for (Klass* sub = chain; sub != NULL; sub = sub->next_sibling()) {
1186       if (do_counts) { NOT_PRODUCT(deps_find_witness_steps++); }
1187       if (is_participant(sub)) {
1188         if (participants_hide_witnesses)  continue;
1189         // else fall through to process this guy's subclasses
1190       } else if (is_witness(sub) && !ignore_witness(sub)) {
1191         return sub;
1192       }
1193       if (chaini < (VerifyDependencies? 2: CHAINMAX)) {
1194         // Fast path.  (Partially disabled if VerifyDependencies.)
1195         ADD_SUBCLASS_CHAIN(sub);
1196       } else {
1197         // Worklist overflow.  Do a recursive call.  Should be rare.
1198         // The recursive call will have its own worklist, of course.
1199         // (Note that sub has already been tested, so that there is
1200         // no need for the recursive call to re-test.  That's handy,
1201         // since the recursive call sees sub as the context_type.)
1202         if (do_counts) { NOT_PRODUCT(deps_find_witness_recursions++); }
1203         Klass* witness = find_witness_anywhere(sub,
1204                                                  participants_hide_witnesses,
1205                                                  /*top_level_call=*/ false);
1206         if (witness != NULL)  return witness;
1207       }
1208     }
1209   }
1210 
1211   // No witness found.  The dependency remains unbroken.
1212   return NULL;
1213 #undef ADD_SUBCLASS_CHAIN
1214 }
1215 
1216 
1217 bool Dependencies::is_concrete_klass(Klass* k) {
1218   if (k->is_abstract())  return false;
1219   // %%% We could treat classes which are concrete but
1220   // have not yet been instantiated as virtually abstract.
1221   // This would require a deoptimization barrier on first instantiation.
1222   //if (k->is_not_instantiated())  return false;
1223   return true;
1224 }
1225 
1226 bool Dependencies::is_concrete_method(Method* m, Klass * k) {
1227   // NULL is not a concrete method,
1228   // statics are irrelevant to virtual call sites,
1229   // abstract methods are not concrete,
1230   // overpass (error) methods are not concrete if k is abstract
1231   //
1232   // note "true" is conservative answer --
1233   //     overpass clause is false if k == NULL, implies return true if
1234   //     answer depends on overpass clause.
1235   return ! ( m == NULL || m -> is_static() || m -> is_abstract() ||
1236              m->is_overpass() && k != NULL && k -> is_abstract() );
1237 }
1238 
1239 
1240 Klass* Dependencies::find_finalizable_subclass(Klass* k) {
1241   if (k->is_interface())  return NULL;
1242   if (k->has_finalizer()) return k;
1243   k = k->subklass();
1244   while (k != NULL) {
1245     Klass* result = find_finalizable_subclass(k);
1246     if (result != NULL) return result;
1247     k = k->next_sibling();
1248   }
1249   return NULL;
1250 }
1251 
1252 
1253 bool Dependencies::is_concrete_klass(ciInstanceKlass* k) {
1254   if (k->is_abstract())  return false;
1255   // We could also return false if k does not yet appear to be
1256   // instantiated, if the VM version supports this distinction also.
1257   //if (k->is_not_instantiated())  return false;
1258   return true;
1259 }
1260 
1261 bool Dependencies::has_finalizable_subclass(ciInstanceKlass* k) {
1262   return k->has_finalizable_subclass();
1263 }
1264 
1265 
1266 // Any use of the contents (bytecodes) of a method must be
1267 // marked by an "evol_method" dependency, if those contents
1268 // can change.  (Note: A method is always dependent on itself.)
1269 Klass* Dependencies::check_evol_method(Method* m) {
1270   assert(must_be_in_vm(), "raw oops here");
1271   // Did somebody do a JVMTI RedefineClasses while our backs were turned?
1272   // Or is there a now a breakpoint?
1273   // (Assumes compiled code cannot handle bkpts; change if UseFastBreakpoints.)
1274   if (m->is_old()
1275       || m->number_of_breakpoints() > 0) {
1276     return m->method_holder();
1277   } else {
1278     return NULL;
1279   }
1280 }
1281 
1282 // This is a strong assertion:  It is that the given type
1283 // has no subtypes whatever.  It is most useful for
1284 // optimizing checks on reflected types or on array types.
1285 // (Checks on types which are derived from real instances
1286 // can be optimized more strongly than this, because we
1287 // know that the checked type comes from a concrete type,
1288 // and therefore we can disregard abstract types.)
1289 Klass* Dependencies::check_leaf_type(Klass* ctxk) {
1290   assert(must_be_in_vm(), "raw oops here");
1291   assert_locked_or_safepoint(Compile_lock);
1292   InstanceKlass* ctx = InstanceKlass::cast(ctxk);
1293   Klass* sub = ctx->subklass();
1294   if (sub != NULL) {
1295     return sub;
1296   } else if (ctx->nof_implementors() != 0) {
1297     // if it is an interface, it must be unimplemented
1298     // (if it is not an interface, nof_implementors is always zero)
1299     Klass* impl = ctx->implementor();
1300     assert(impl != NULL, "must be set");
1301     return impl;
1302   } else {
1303     return NULL;
1304   }
1305 }
1306 
1307 // Test the assertion that conck is the only concrete subtype* of ctxk.
1308 // The type conck itself is allowed to have have further concrete subtypes.
1309 // This allows the compiler to narrow occurrences of ctxk by conck,
1310 // when dealing with the types of actual instances.
1311 Klass* Dependencies::check_abstract_with_unique_concrete_subtype(Klass* ctxk,
1312                                                                    Klass* conck,
1313                                                                    KlassDepChange* changes) {
1314   ClassHierarchyWalker wf(conck);
1315   return wf.find_witness_subtype(ctxk, changes);
1316 }
1317 
1318 // If a non-concrete class has no concrete subtypes, it is not (yet)
1319 // instantiatable.  This can allow the compiler to make some paths go
1320 // dead, if they are gated by a test of the type.
1321 Klass* Dependencies::check_abstract_with_no_concrete_subtype(Klass* ctxk,
1322                                                                KlassDepChange* changes) {
1323   // Find any concrete subtype, with no participants:
1324   ClassHierarchyWalker wf;
1325   return wf.find_witness_subtype(ctxk, changes);
1326 }
1327 
1328 
1329 // If a concrete class has no concrete subtypes, it can always be
1330 // exactly typed.  This allows the use of a cheaper type test.
1331 Klass* Dependencies::check_concrete_with_no_concrete_subtype(Klass* ctxk,
1332                                                                KlassDepChange* changes) {
1333   // Find any concrete subtype, with only the ctxk as participant:
1334   ClassHierarchyWalker wf(ctxk);
1335   return wf.find_witness_subtype(ctxk, changes);
1336 }
1337 
1338 
1339 // Find the unique concrete proper subtype of ctxk, or NULL if there
1340 // is more than one concrete proper subtype.  If there are no concrete
1341 // proper subtypes, return ctxk itself, whether it is concrete or not.
1342 // The returned subtype is allowed to have have further concrete subtypes.
1343 // That is, return CC1 for CX > CC1 > CC2, but NULL for CX > { CC1, CC2 }.
1344 Klass* Dependencies::find_unique_concrete_subtype(Klass* ctxk) {
1345   ClassHierarchyWalker wf(ctxk);   // Ignore ctxk when walking.
1346   wf.record_witnesses(1);          // Record one other witness when walking.
1347   Klass* wit = wf.find_witness_subtype(ctxk);
1348   if (wit != NULL)  return NULL;   // Too many witnesses.
1349   Klass* conck = wf.participant(0);
1350   if (conck == NULL) {
1351 #ifndef PRODUCT
1352     // Make sure the dependency mechanism will pass this discovery:
1353     if (VerifyDependencies) {
1354       // Turn off dependency tracing while actually testing deps.
1355       FlagSetting fs(TraceDependencies, false);
1356       if (!Dependencies::is_concrete_klass(ctxk)) {
1357         guarantee(NULL ==
1358                   (void *)check_abstract_with_no_concrete_subtype(ctxk),
1359                   "verify dep.");
1360       } else {
1361         guarantee(NULL ==
1362                   (void *)check_concrete_with_no_concrete_subtype(ctxk),
1363                   "verify dep.");
1364       }
1365     }
1366 #endif //PRODUCT
1367     return ctxk;                   // Return ctxk as a flag for "no subtypes".
1368   } else {
1369 #ifndef PRODUCT
1370     // Make sure the dependency mechanism will pass this discovery:
1371     if (VerifyDependencies) {
1372       // Turn off dependency tracing while actually testing deps.
1373       FlagSetting fs(TraceDependencies, false);
1374       if (!Dependencies::is_concrete_klass(ctxk)) {
1375         guarantee(NULL == (void *)
1376                   check_abstract_with_unique_concrete_subtype(ctxk, conck),
1377                   "verify dep.");
1378       }
1379     }
1380 #endif //PRODUCT
1381     return conck;
1382   }
1383 }
1384 
1385 // Test the assertion that the k[12] are the only concrete subtypes of ctxk,
1386 // except possibly for further subtypes of k[12] themselves.
1387 // The context type must be abstract.  The types k1 and k2 are themselves
1388 // allowed to have further concrete subtypes.
1389 Klass* Dependencies::check_abstract_with_exclusive_concrete_subtypes(
1390                                                 Klass* ctxk,
1391                                                 Klass* k1,
1392                                                 Klass* k2,
1393                                                 KlassDepChange* changes) {
1394   ClassHierarchyWalker wf;
1395   wf.add_participant(k1);
1396   wf.add_participant(k2);
1397   return wf.find_witness_subtype(ctxk, changes);
1398 }
1399 
1400 // Search ctxk for concrete implementations.  If there are klen or fewer,
1401 // pack them into the given array and return the number.
1402 // Otherwise, return -1, meaning the given array would overflow.
1403 // (Note that a return of 0 means there are exactly no concrete subtypes.)
1404 // In this search, if ctxk is concrete, it will be reported alone.
1405 // For any type CC reported, no proper subtypes of CC will be reported.
1406 int Dependencies::find_exclusive_concrete_subtypes(Klass* ctxk,
1407                                                    int klen,
1408                                                    Klass* karray[]) {
1409   ClassHierarchyWalker wf;
1410   wf.record_witnesses(klen);
1411   Klass* wit = wf.find_witness_subtype(ctxk);
1412   if (wit != NULL)  return -1;  // Too many witnesses.
1413   int num = wf.num_participants();
1414   assert(num <= klen, "oob");
1415   // Pack the result array with the good news.
1416   for (int i = 0; i < num; i++)
1417     karray[i] = wf.participant(i);
1418 #ifndef PRODUCT
1419   // Make sure the dependency mechanism will pass this discovery:
1420   if (VerifyDependencies) {
1421     // Turn off dependency tracing while actually testing deps.
1422     FlagSetting fs(TraceDependencies, false);
1423     switch (Dependencies::is_concrete_klass(ctxk)? -1: num) {
1424     case -1: // ctxk was itself concrete
1425       guarantee(num == 1 && karray[0] == ctxk, "verify dep.");
1426       break;
1427     case 0:
1428       guarantee(NULL == (void *)check_abstract_with_no_concrete_subtype(ctxk),
1429                 "verify dep.");
1430       break;
1431     case 1:
1432       guarantee(NULL == (void *)
1433                 check_abstract_with_unique_concrete_subtype(ctxk, karray[0]),
1434                 "verify dep.");
1435       break;
1436     case 2:
1437       guarantee(NULL == (void *)
1438                 check_abstract_with_exclusive_concrete_subtypes(ctxk,
1439                                                                 karray[0],
1440                                                                 karray[1]),
1441                 "verify dep.");
1442       break;
1443     default:
1444       ShouldNotReachHere();  // klen > 2 yet supported
1445     }
1446   }
1447 #endif //PRODUCT
1448   return num;
1449 }
1450 
1451 // If a class (or interface) has a unique concrete method uniqm, return NULL.
1452 // Otherwise, return a class that contains an interfering method.
1453 Klass* Dependencies::check_unique_concrete_method(Klass* ctxk, Method* uniqm,
1454                                                     KlassDepChange* changes) {
1455   // Here is a missing optimization:  If uniqm->is_final(),
1456   // we don't really need to search beneath it for overrides.
1457   // This is probably not important, since we don't use dependencies
1458   // to track final methods.  (They can't be "definalized".)
1459   ClassHierarchyWalker wf(uniqm->method_holder(), uniqm);
1460   return wf.find_witness_definer(ctxk, changes);
1461 }
1462 
1463 // Find the set of all non-abstract methods under ctxk that match m.
1464 // (The method m must be defined or inherited in ctxk.)
1465 // Include m itself in the set, unless it is abstract.
1466 // If this set has exactly one element, return that element.
1467 Method* Dependencies::find_unique_concrete_method(Klass* ctxk, Method* m) {
1468   // Return NULL if m is marked old; must have been a redefined method.
1469   if (m->is_old()) {
1470     return NULL;
1471   }
1472   ClassHierarchyWalker wf(m);
1473   assert(wf.check_method_context(ctxk, m), "proper context");
1474   wf.record_witnesses(1);
1475   Klass* wit = wf.find_witness_definer(ctxk);
1476   if (wit != NULL)  return NULL;  // Too many witnesses.
1477   Method* fm = wf.found_method(0);  // Will be NULL if num_parts == 0.
1478   if (Dependencies::is_concrete_method(m, ctxk)) {
1479     if (fm == NULL) {
1480       // It turns out that m was always the only implementation.
1481       fm = m;
1482     } else if (fm != m) {
1483       // Two conflicting implementations after all.
1484       // (This can happen if m is inherited into ctxk and fm overrides it.)
1485       return NULL;
1486     }
1487   }
1488 #ifndef PRODUCT
1489   // Make sure the dependency mechanism will pass this discovery:
1490   if (VerifyDependencies && fm != NULL) {
1491     guarantee(NULL == (void *)check_unique_concrete_method(ctxk, fm),
1492               "verify dep.");
1493   }
1494 #endif //PRODUCT
1495   return fm;
1496 }
1497 
1498 Klass* Dependencies::check_exclusive_concrete_methods(Klass* ctxk,
1499                                                         Method* m1,
1500                                                         Method* m2,
1501                                                         KlassDepChange* changes) {
1502   ClassHierarchyWalker wf(m1);
1503   wf.add_participant(m1->method_holder());
1504   wf.add_participant(m2->method_holder());
1505   return wf.find_witness_definer(ctxk, changes);
1506 }
1507 
1508 Klass* Dependencies::check_has_no_finalizable_subclasses(Klass* ctxk, KlassDepChange* changes) {
1509   Klass* search_at = ctxk;
1510   if (changes != NULL)
1511     search_at = changes->new_type(); // just look at the new bit
1512   return find_finalizable_subclass(search_at);
1513 }
1514 
1515 Klass* Dependencies::check_call_site_target_value(oop call_site, oop method_handle, CallSiteDepChange* changes) {
1516   assert(!oopDesc::is_null(call_site), "sanity");
1517   assert(!oopDesc::is_null(method_handle), "sanity");
1518   assert(call_site->is_a(SystemDictionary::CallSite_klass()),     "sanity");
1519 
1520   if (changes == NULL) {
1521     // Validate all CallSites
1522     if (java_lang_invoke_CallSite::target(call_site) != method_handle)
1523       return call_site->klass();  // assertion failed
1524   } else {
1525     // Validate the given CallSite
1526     if (call_site == changes->call_site() && java_lang_invoke_CallSite::target(call_site) != changes->method_handle()) {
1527       assert(method_handle != changes->method_handle(), "must be");
1528       return call_site->klass();  // assertion failed
1529     }
1530   }
1531   return NULL;  // assertion still valid
1532 }
1533 
















1534 void Dependencies::DepStream::trace_and_log_witness(Klass* witness) {
1535   if (witness != NULL) {
1536     if (TraceDependencies) {
1537       print_dependency(witness, /*verbose=*/ true);
1538     }
1539     // The following is a no-op unless logging is enabled:
1540     log_dependency(witness);
1541   }
1542 }
1543 
1544 
1545 Klass* Dependencies::DepStream::check_klass_dependency(KlassDepChange* changes) {
1546   assert_locked_or_safepoint(Compile_lock);
1547   Dependencies::check_valid_dependency_type(type());
1548 
1549   Klass* witness = NULL;
1550   switch (type()) {
1551   case evol_method:
1552     witness = check_evol_method(method_argument(0));
1553     break;
1554   case leaf_type:
1555     witness = check_leaf_type(context_type());
1556     break;
1557   case abstract_with_unique_concrete_subtype:
1558     witness = check_abstract_with_unique_concrete_subtype(context_type(), type_argument(1), changes);
1559     break;
1560   case abstract_with_no_concrete_subtype:
1561     witness = check_abstract_with_no_concrete_subtype(context_type(), changes);
1562     break;
1563   case concrete_with_no_concrete_subtype:
1564     witness = check_concrete_with_no_concrete_subtype(context_type(), changes);
1565     break;
1566   case unique_concrete_method:
1567     witness = check_unique_concrete_method(context_type(), method_argument(1), changes);
1568     break;
1569   case abstract_with_exclusive_concrete_subtypes_2:
1570     witness = check_abstract_with_exclusive_concrete_subtypes(context_type(), type_argument(1), type_argument(2), changes);
1571     break;
1572   case exclusive_concrete_methods_2:
1573     witness = check_exclusive_concrete_methods(context_type(), method_argument(1), method_argument(2), changes);
1574     break;
1575   case no_finalizable_subclasses:
1576     witness = check_has_no_finalizable_subclasses(context_type(), changes);
1577     break;
1578   default:
1579     witness = NULL;
1580     break;
1581   }
1582   trace_and_log_witness(witness);
1583   return witness;
1584 }
1585 
1586 
1587 Klass* Dependencies::DepStream::check_call_site_dependency(CallSiteDepChange* changes) {
1588   assert_locked_or_safepoint(Compile_lock);
1589   Dependencies::check_valid_dependency_type(type());
1590 
1591   Klass* witness = NULL;
1592   switch (type()) {
1593   case call_site_target_value:
1594     witness = check_call_site_target_value(argument_oop(0), argument_oop(1), changes);
1595     break;
1596   default:
1597     witness = NULL;
1598     break;
1599   }
1600   trace_and_log_witness(witness);
1601   return witness;
1602 }
1603 
1604 
1605 Klass* Dependencies::DepStream::spot_check_dependency_at(DepChange& changes) {
1606   // Handle klass dependency
1607   if (changes.is_klass_change() && changes.as_klass_change()->involves_context(context_type()))
1608     return check_klass_dependency(changes.as_klass_change());
1609 
1610   // Handle CallSite dependency
1611   if (changes.is_call_site_change())
1612     return check_call_site_dependency(changes.as_call_site_change());
1613 



















1614   // irrelevant dependency; skip it
1615   return NULL;
1616 }
1617 
1618 
1619 void DepChange::print() {






1620   int nsup = 0, nint = 0;
1621   for (ContextStream str(*this); str.next(); ) {
1622     Klass* k = str.klass();
1623     switch (str.change_type()) {
1624     case Change_new_type:
1625       tty->print_cr("  dependee = %s", InstanceKlass::cast(k)->external_name());
1626       break;
1627     case Change_new_sub:
1628       if (!WizardMode) {
1629         ++nsup;
1630       } else {
1631         tty->print_cr("  context super = %s", InstanceKlass::cast(k)->external_name());
1632       }
1633       break;
1634     case Change_new_impl:
1635       if (!WizardMode) {
1636         ++nint;
1637       } else {
1638         tty->print_cr("  context interface = %s", InstanceKlass::cast(k)->external_name());
1639       }
1640       break;
1641     }
1642   }
1643   if (nsup + nint != 0) {
1644     tty->print_cr("  context supers = %d, interfaces = %d", nsup, nint);
1645   }
1646 }
1647 
1648 void DepChange::ContextStream::start() {
1649   Klass* new_type = _changes.is_klass_change() ? _changes.as_klass_change()->new_type() : (Klass*) NULL;
1650   _change_type = (new_type == NULL ? NO_CHANGE : Start_Klass);
1651   _klass = new_type;
1652   _ti_base = NULL;
1653   _ti_index = 0;
1654   _ti_limit = 0;
1655 }
1656 
1657 bool DepChange::ContextStream::next() {
1658   switch (_change_type) {
1659   case Start_Klass:             // initial state; _klass is the new type
1660     _ti_base = InstanceKlass::cast(_klass)->transitive_interfaces();
1661     _ti_index = 0;
1662     _change_type = Change_new_type;
1663     return true;
1664   case Change_new_type:
1665     // fall through:
1666     _change_type = Change_new_sub;
1667   case Change_new_sub:
1668     // 6598190: brackets workaround Sun Studio C++ compiler bug 6629277
1669     {
1670       _klass = InstanceKlass::cast(_klass)->super();
1671       if (_klass != NULL) {
1672         return true;
1673       }
1674     }
1675     // else set up _ti_limit and fall through:
1676     _ti_limit = (_ti_base == NULL) ? 0 : _ti_base->length();
1677     _change_type = Change_new_impl;
1678   case Change_new_impl:
1679     if (_ti_index < _ti_limit) {
1680       _klass = _ti_base->at(_ti_index++);
1681       return true;
1682     }
1683     // fall through:
1684     _change_type = NO_CHANGE;  // iterator is exhausted
1685   case NO_CHANGE:
1686     break;
1687   default:
1688     ShouldNotReachHere();
1689   }
1690   return false;
1691 }
1692 
1693 void KlassDepChange::initialize() {
1694   // entire transaction must be under this lock:
1695   assert_lock_strong(Compile_lock);
1696 
1697   // Mark all dependee and all its superclasses
1698   // Mark transitive interfaces
1699   for (ContextStream str(*this); str.next(); ) {
1700     Klass* d = str.klass();
1701     assert(!InstanceKlass::cast(d)->is_marked_dependent(), "checking");
1702     InstanceKlass::cast(d)->set_is_marked_dependent(true);
1703   }
1704 }
1705 
1706 KlassDepChange::~KlassDepChange() {
1707   // Unmark all dependee and all its superclasses
1708   // Unmark transitive interfaces
1709   for (ContextStream str(*this); str.next(); ) {
1710     Klass* d = str.klass();
1711     InstanceKlass::cast(d)->set_is_marked_dependent(false);
1712   }
1713 }
1714 
1715 bool KlassDepChange::involves_context(Klass* k) {
1716   if (k == NULL || !k->oop_is_instance()) {
1717     return false;
1718   }
1719   InstanceKlass* ik = InstanceKlass::cast(k);
1720   bool is_contained = ik->is_marked_dependent();
1721   assert(is_contained == new_type()->is_subtype_of(k),
1722          "correct marking of potential context types");
1723   return is_contained;
1724 }
1725 
1726 #ifndef PRODUCT
1727 void Dependencies::print_statistics() {
1728   if (deps_find_witness_print != 0) {
1729     // Call one final time, to flush out the data.
1730     deps_find_witness_print = -1;
1731     count_find_witness_calls();
1732   }
1733 }
1734 #endif
--- EOF ---