1 /*
   2  * Copyright (c) 1997, 2014, 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 "asm/macroAssembler.hpp"
  27 #include "asm/macroAssembler.inline.hpp"
  28 #include "ci/ciReplay.hpp"
  29 #include "classfile/systemDictionary.hpp"
  30 #include "code/exceptionHandlerTable.hpp"
  31 #include "code/nmethod.hpp"
  32 #include "compiler/compileBroker.hpp"
  33 #include "compiler/compileLog.hpp"
  34 #include "compiler/disassembler.hpp"
  35 #include "compiler/oopMap.hpp"
  36 #include "opto/addnode.hpp"
  37 #include "opto/block.hpp"
  38 #include "opto/c2compiler.hpp"
  39 #include "opto/callGenerator.hpp"
  40 #include "opto/callnode.hpp"
  41 #include "opto/cfgnode.hpp"
  42 #include "opto/chaitin.hpp"
  43 #include "opto/compile.hpp"
  44 #include "opto/connode.hpp"
  45 #include "opto/divnode.hpp"
  46 #include "opto/escape.hpp"
  47 #include "opto/idealGraphPrinter.hpp"
  48 #include "opto/loopnode.hpp"
  49 #include "opto/machnode.hpp"
  50 #include "opto/macro.hpp"
  51 #include "opto/matcher.hpp"
  52 #include "opto/mathexactnode.hpp"
  53 #include "opto/memnode.hpp"
  54 #include "opto/mulnode.hpp"
  55 #include "opto/narrowptrnode.hpp"
  56 #include "opto/node.hpp"
  57 #include "opto/opcodes.hpp"
  58 #include "opto/output.hpp"
  59 #include "opto/parse.hpp"
  60 #include "opto/phaseX.hpp"
  61 #include "opto/rootnode.hpp"
  62 #include "opto/runtime.hpp"
  63 #include "opto/stringopts.hpp"
  64 #include "opto/type.hpp"
  65 #include "opto/vectornode.hpp"
  66 #include "runtime/arguments.hpp"
  67 #include "runtime/signature.hpp"
  68 #include "runtime/stubRoutines.hpp"
  69 #include "runtime/timer.hpp"
  70 #include "trace/tracing.hpp"
  71 #include "utilities/copy.hpp"
  72 
  73 
  74 // -------------------- Compile::mach_constant_base_node -----------------------
  75 // Constant table base node singleton.
  76 MachConstantBaseNode* Compile::mach_constant_base_node() {
  77   if (_mach_constant_base_node == NULL) {
  78     _mach_constant_base_node = new MachConstantBaseNode();
  79     _mach_constant_base_node->add_req(C->root());
  80   }
  81   return _mach_constant_base_node;
  82 }
  83 
  84 
  85 /// Support for intrinsics.
  86 
  87 // Return the index at which m must be inserted (or already exists).
  88 // The sort order is by the address of the ciMethod, with is_virtual as minor key.
  89 int Compile::intrinsic_insertion_index(ciMethod* m, bool is_virtual) {
  90 #ifdef ASSERT
  91   for (int i = 1; i < _intrinsics->length(); i++) {
  92     CallGenerator* cg1 = _intrinsics->at(i-1);
  93     CallGenerator* cg2 = _intrinsics->at(i);
  94     assert(cg1->method() != cg2->method()
  95            ? cg1->method()     < cg2->method()
  96            : cg1->is_virtual() < cg2->is_virtual(),
  97            "compiler intrinsics list must stay sorted");
  98   }
  99 #endif
 100   // Binary search sorted list, in decreasing intervals [lo, hi].
 101   int lo = 0, hi = _intrinsics->length()-1;
 102   while (lo <= hi) {
 103     int mid = (uint)(hi + lo) / 2;
 104     ciMethod* mid_m = _intrinsics->at(mid)->method();
 105     if (m < mid_m) {
 106       hi = mid-1;
 107     } else if (m > mid_m) {
 108       lo = mid+1;
 109     } else {
 110       // look at minor sort key
 111       bool mid_virt = _intrinsics->at(mid)->is_virtual();
 112       if (is_virtual < mid_virt) {
 113         hi = mid-1;
 114       } else if (is_virtual > mid_virt) {
 115         lo = mid+1;
 116       } else {
 117         return mid;  // exact match
 118       }
 119     }
 120   }
 121   return lo;  // inexact match
 122 }
 123 
 124 void Compile::register_intrinsic(CallGenerator* cg) {
 125   if (_intrinsics == NULL) {
 126     _intrinsics = new (comp_arena())GrowableArray<CallGenerator*>(comp_arena(), 60, 0, NULL);
 127   }
 128   // This code is stolen from ciObjectFactory::insert.
 129   // Really, GrowableArray should have methods for
 130   // insert_at, remove_at, and binary_search.
 131   int len = _intrinsics->length();
 132   int index = intrinsic_insertion_index(cg->method(), cg->is_virtual());
 133   if (index == len) {
 134     _intrinsics->append(cg);
 135   } else {
 136 #ifdef ASSERT
 137     CallGenerator* oldcg = _intrinsics->at(index);
 138     assert(oldcg->method() != cg->method() || oldcg->is_virtual() != cg->is_virtual(), "don't register twice");
 139 #endif
 140     _intrinsics->append(_intrinsics->at(len-1));
 141     int pos;
 142     for (pos = len-2; pos >= index; pos--) {
 143       _intrinsics->at_put(pos+1,_intrinsics->at(pos));
 144     }
 145     _intrinsics->at_put(index, cg);
 146   }
 147   assert(find_intrinsic(cg->method(), cg->is_virtual()) == cg, "registration worked");
 148 }
 149 
 150 CallGenerator* Compile::find_intrinsic(ciMethod* m, bool is_virtual) {
 151   assert(m->is_loaded(), "don't try this on unloaded methods");
 152   if (_intrinsics != NULL) {
 153     int index = intrinsic_insertion_index(m, is_virtual);
 154     if (index < _intrinsics->length()
 155         && _intrinsics->at(index)->method() == m
 156         && _intrinsics->at(index)->is_virtual() == is_virtual) {
 157       return _intrinsics->at(index);
 158     }
 159   }
 160   // Lazily create intrinsics for intrinsic IDs well-known in the runtime.
 161   if (m->intrinsic_id() != vmIntrinsics::_none &&
 162       m->intrinsic_id() <= vmIntrinsics::LAST_COMPILER_INLINE) {
 163     CallGenerator* cg = make_vm_intrinsic(m, is_virtual);
 164     if (cg != NULL) {
 165       // Save it for next time:
 166       register_intrinsic(cg);
 167       return cg;
 168     } else {
 169       gather_intrinsic_statistics(m->intrinsic_id(), is_virtual, _intrinsic_disabled);
 170     }
 171   }
 172   return NULL;
 173 }
 174 
 175 // Compile:: register_library_intrinsics and make_vm_intrinsic are defined
 176 // in library_call.cpp.
 177 
 178 
 179 #ifndef PRODUCT
 180 // statistics gathering...
 181 
 182 juint  Compile::_intrinsic_hist_count[vmIntrinsics::ID_LIMIT] = {0};
 183 jubyte Compile::_intrinsic_hist_flags[vmIntrinsics::ID_LIMIT] = {0};
 184 
 185 bool Compile::gather_intrinsic_statistics(vmIntrinsics::ID id, bool is_virtual, int flags) {
 186   assert(id > vmIntrinsics::_none && id < vmIntrinsics::ID_LIMIT, "oob");
 187   int oflags = _intrinsic_hist_flags[id];
 188   assert(flags != 0, "what happened?");
 189   if (is_virtual) {
 190     flags |= _intrinsic_virtual;
 191   }
 192   bool changed = (flags != oflags);
 193   if ((flags & _intrinsic_worked) != 0) {
 194     juint count = (_intrinsic_hist_count[id] += 1);
 195     if (count == 1) {
 196       changed = true;           // first time
 197     }
 198     // increment the overall count also:
 199     _intrinsic_hist_count[vmIntrinsics::_none] += 1;
 200   }
 201   if (changed) {
 202     if (((oflags ^ flags) & _intrinsic_virtual) != 0) {
 203       // Something changed about the intrinsic's virtuality.
 204       if ((flags & _intrinsic_virtual) != 0) {
 205         // This is the first use of this intrinsic as a virtual call.
 206         if (oflags != 0) {
 207           // We already saw it as a non-virtual, so note both cases.
 208           flags |= _intrinsic_both;
 209         }
 210       } else if ((oflags & _intrinsic_both) == 0) {
 211         // This is the first use of this intrinsic as a non-virtual
 212         flags |= _intrinsic_both;
 213       }
 214     }
 215     _intrinsic_hist_flags[id] = (jubyte) (oflags | flags);
 216   }
 217   // update the overall flags also:
 218   _intrinsic_hist_flags[vmIntrinsics::_none] |= (jubyte) flags;
 219   return changed;
 220 }
 221 
 222 static char* format_flags(int flags, char* buf) {
 223   buf[0] = 0;
 224   if ((flags & Compile::_intrinsic_worked) != 0)    strcat(buf, ",worked");
 225   if ((flags & Compile::_intrinsic_failed) != 0)    strcat(buf, ",failed");
 226   if ((flags & Compile::_intrinsic_disabled) != 0)  strcat(buf, ",disabled");
 227   if ((flags & Compile::_intrinsic_virtual) != 0)   strcat(buf, ",virtual");
 228   if ((flags & Compile::_intrinsic_both) != 0)      strcat(buf, ",nonvirtual");
 229   if (buf[0] == 0)  strcat(buf, ",");
 230   assert(buf[0] == ',', "must be");
 231   return &buf[1];
 232 }
 233 
 234 void Compile::print_intrinsic_statistics() {
 235   char flagsbuf[100];
 236   ttyLocker ttyl;
 237   if (xtty != NULL)  xtty->head("statistics type='intrinsic'");
 238   tty->print_cr("Compiler intrinsic usage:");
 239   juint total = _intrinsic_hist_count[vmIntrinsics::_none];
 240   if (total == 0)  total = 1;  // avoid div0 in case of no successes
 241   #define PRINT_STAT_LINE(name, c, f) \
 242     tty->print_cr("  %4d (%4.1f%%) %s (%s)", (int)(c), ((c) * 100.0) / total, name, f);
 243   for (int index = 1 + (int)vmIntrinsics::_none; index < (int)vmIntrinsics::ID_LIMIT; index++) {
 244     vmIntrinsics::ID id = (vmIntrinsics::ID) index;
 245     int   flags = _intrinsic_hist_flags[id];
 246     juint count = _intrinsic_hist_count[id];
 247     if ((flags | count) != 0) {
 248       PRINT_STAT_LINE(vmIntrinsics::name_at(id), count, format_flags(flags, flagsbuf));
 249     }
 250   }
 251   PRINT_STAT_LINE("total", total, format_flags(_intrinsic_hist_flags[vmIntrinsics::_none], flagsbuf));
 252   if (xtty != NULL)  xtty->tail("statistics");
 253 }
 254 
 255 void Compile::print_statistics() {
 256   { ttyLocker ttyl;
 257     if (xtty != NULL)  xtty->head("statistics type='opto'");
 258     Parse::print_statistics();
 259     PhaseCCP::print_statistics();
 260     PhaseRegAlloc::print_statistics();
 261     Scheduling::print_statistics();
 262     PhasePeephole::print_statistics();
 263     PhaseIdealLoop::print_statistics();
 264     if (xtty != NULL)  xtty->tail("statistics");
 265   }
 266   if (_intrinsic_hist_flags[vmIntrinsics::_none] != 0) {
 267     // put this under its own <statistics> element.
 268     print_intrinsic_statistics();
 269   }
 270 }
 271 #endif //PRODUCT
 272 
 273 // Support for bundling info
 274 Bundle* Compile::node_bundling(const Node *n) {
 275   assert(valid_bundle_info(n), "oob");
 276   return &_node_bundling_base[n->_idx];
 277 }
 278 
 279 bool Compile::valid_bundle_info(const Node *n) {
 280   return (_node_bundling_limit > n->_idx);
 281 }
 282 
 283 
 284 void Compile::gvn_replace_by(Node* n, Node* nn) {
 285   for (DUIterator_Last imin, i = n->last_outs(imin); i >= imin; ) {
 286     Node* use = n->last_out(i);
 287     bool is_in_table = initial_gvn()->hash_delete(use);
 288     uint uses_found = 0;
 289     for (uint j = 0; j < use->len(); j++) {
 290       if (use->in(j) == n) {
 291         if (j < use->req())
 292           use->set_req(j, nn);
 293         else
 294           use->set_prec(j, nn);
 295         uses_found++;
 296       }
 297     }
 298     if (is_in_table) {
 299       // reinsert into table
 300       initial_gvn()->hash_find_insert(use);
 301     }
 302     record_for_igvn(use);
 303     i -= uses_found;    // we deleted 1 or more copies of this edge
 304   }
 305 }
 306 
 307 
 308 static inline bool not_a_node(const Node* n) {
 309   if (n == NULL)                   return true;
 310   if (((intptr_t)n & 1) != 0)      return true;  // uninitialized, etc.
 311   if (*(address*)n == badAddress)  return true;  // kill by Node::destruct
 312   return false;
 313 }
 314 
 315 // Identify all nodes that are reachable from below, useful.
 316 // Use breadth-first pass that records state in a Unique_Node_List,
 317 // recursive traversal is slower.
 318 void Compile::identify_useful_nodes(Unique_Node_List &useful) {
 319   int estimated_worklist_size = unique();
 320   useful.map( estimated_worklist_size, NULL );  // preallocate space
 321 
 322   // Initialize worklist
 323   if (root() != NULL)     { useful.push(root()); }
 324   // If 'top' is cached, declare it useful to preserve cached node
 325   if( cached_top_node() ) { useful.push(cached_top_node()); }
 326 
 327   // Push all useful nodes onto the list, breadthfirst
 328   for( uint next = 0; next < useful.size(); ++next ) {
 329     assert( next < unique(), "Unique useful nodes < total nodes");
 330     Node *n  = useful.at(next);
 331     uint max = n->len();
 332     for( uint i = 0; i < max; ++i ) {
 333       Node *m = n->in(i);
 334       if (not_a_node(m))  continue;
 335       useful.push(m);
 336     }
 337   }
 338 }
 339 
 340 // Update dead_node_list with any missing dead nodes using useful
 341 // list. Consider all non-useful nodes to be useless i.e., dead nodes.
 342 void Compile::update_dead_node_list(Unique_Node_List &useful) {
 343   uint max_idx = unique();
 344   VectorSet& useful_node_set = useful.member_set();
 345 
 346   for (uint node_idx = 0; node_idx < max_idx; node_idx++) {
 347     // If node with index node_idx is not in useful set,
 348     // mark it as dead in dead node list.
 349     if (! useful_node_set.test(node_idx) ) {
 350       record_dead_node(node_idx);
 351     }
 352   }
 353 }
 354 
 355 void Compile::remove_useless_late_inlines(GrowableArray<CallGenerator*>* inlines, Unique_Node_List &useful) {
 356   int shift = 0;
 357   for (int i = 0; i < inlines->length(); i++) {
 358     CallGenerator* cg = inlines->at(i);
 359     CallNode* call = cg->call_node();
 360     if (shift > 0) {
 361       inlines->at_put(i-shift, cg);
 362     }
 363     if (!useful.member(call)) {
 364       shift++;
 365     }
 366   }
 367   inlines->trunc_to(inlines->length()-shift);
 368 }
 369 
 370 // Disconnect all useless nodes by disconnecting those at the boundary.
 371 void Compile::remove_useless_nodes(Unique_Node_List &useful) {
 372   uint next = 0;
 373   while (next < useful.size()) {
 374     Node *n = useful.at(next++);
 375     if (n->is_SafePoint()) {
 376       // We're done with a parsing phase. Replaced nodes are not valid
 377       // beyond that point.
 378       n->as_SafePoint()->delete_replaced_nodes();
 379     }
 380     // Use raw traversal of out edges since this code removes out edges
 381     int max = n->outcnt();
 382     for (int j = 0; j < max; ++j) {
 383       Node* child = n->raw_out(j);
 384       if (! useful.member(child)) {
 385         assert(!child->is_top() || child != top(),
 386                "If top is cached in Compile object it is in useful list");
 387         // Only need to remove this out-edge to the useless node
 388         n->raw_del_out(j);
 389         --j;
 390         --max;
 391       }
 392     }
 393     if (n->outcnt() == 1 && n->has_special_unique_user()) {
 394       record_for_igvn(n->unique_out());
 395     }
 396   }
 397   // Remove useless macro and predicate opaq nodes
 398   for (int i = C->macro_count()-1; i >= 0; i--) {
 399     Node* n = C->macro_node(i);
 400     if (!useful.member(n)) {
 401       remove_macro_node(n);
 402     }
 403   }
 404   // Remove useless expensive node
 405   for (int i = C->expensive_count()-1; i >= 0; i--) {
 406     Node* n = C->expensive_node(i);
 407     if (!useful.member(n)) {
 408       remove_expensive_node(n);
 409     }
 410   }
 411   // clean up the late inline lists
 412   remove_useless_late_inlines(&_string_late_inlines, useful);
 413   remove_useless_late_inlines(&_boxing_late_inlines, useful);
 414   remove_useless_late_inlines(&_late_inlines, useful);
 415   debug_only(verify_graph_edges(true/*check for no_dead_code*/);)
 416 }
 417 
 418 //------------------------------frame_size_in_words-----------------------------
 419 // frame_slots in units of words
 420 int Compile::frame_size_in_words() const {
 421   // shift is 0 in LP32 and 1 in LP64
 422   const int shift = (LogBytesPerWord - LogBytesPerInt);
 423   int words = _frame_slots >> shift;
 424   assert( words << shift == _frame_slots, "frame size must be properly aligned in LP64" );
 425   return words;
 426 }
 427 
 428 // To bang the stack of this compiled method we use the stack size
 429 // that the interpreter would need in case of a deoptimization. This
 430 // removes the need to bang the stack in the deoptimization blob which
 431 // in turn simplifies stack overflow handling.
 432 int Compile::bang_size_in_bytes() const {
 433   return MAX2(_interpreter_frame_size, frame_size_in_bytes());
 434 }
 435 
 436 // ============================================================================
 437 //------------------------------CompileWrapper---------------------------------
 438 class CompileWrapper : public StackObj {
 439   Compile *const _compile;
 440  public:
 441   CompileWrapper(Compile* compile);
 442 
 443   ~CompileWrapper();
 444 };
 445 
 446 CompileWrapper::CompileWrapper(Compile* compile) : _compile(compile) {
 447   // the Compile* pointer is stored in the current ciEnv:
 448   ciEnv* env = compile->env();
 449   assert(env == ciEnv::current(), "must already be a ciEnv active");
 450   assert(env->compiler_data() == NULL, "compile already active?");
 451   env->set_compiler_data(compile);
 452   assert(compile == Compile::current(), "sanity");
 453 
 454   compile->set_type_dict(NULL);
 455   compile->set_type_hwm(NULL);
 456   compile->set_type_last_size(0);
 457   compile->set_last_tf(NULL, NULL);
 458   compile->set_indexSet_arena(NULL);
 459   compile->set_indexSet_free_block_list(NULL);
 460   compile->init_type_arena();
 461   Type::Initialize(compile);
 462   _compile->set_scratch_buffer_blob(NULL);
 463   _compile->begin_method();
 464 }
 465 CompileWrapper::~CompileWrapper() {
 466   _compile->end_method();
 467   if (_compile->scratch_buffer_blob() != NULL)
 468     BufferBlob::free(_compile->scratch_buffer_blob());
 469   _compile->env()->set_compiler_data(NULL);
 470 }
 471 
 472 
 473 //----------------------------print_compile_messages---------------------------
 474 void Compile::print_compile_messages() {
 475 #ifndef PRODUCT
 476   // Check if recompiling
 477   if (_subsume_loads == false && PrintOpto) {
 478     // Recompiling without allowing machine instructions to subsume loads
 479     tty->print_cr("*********************************************************");
 480     tty->print_cr("** Bailout: Recompile without subsuming loads          **");
 481     tty->print_cr("*********************************************************");
 482   }
 483   if (_do_escape_analysis != DoEscapeAnalysis && PrintOpto) {
 484     // Recompiling without escape analysis
 485     tty->print_cr("*********************************************************");
 486     tty->print_cr("** Bailout: Recompile without escape analysis          **");
 487     tty->print_cr("*********************************************************");
 488   }
 489   if (_eliminate_boxing != EliminateAutoBox && PrintOpto) {
 490     // Recompiling without boxing elimination
 491     tty->print_cr("*********************************************************");
 492     tty->print_cr("** Bailout: Recompile without boxing elimination       **");
 493     tty->print_cr("*********************************************************");
 494   }
 495   if (env()->break_at_compile()) {
 496     // Open the debugger when compiling this method.
 497     tty->print("### Breaking when compiling: ");
 498     method()->print_short_name();
 499     tty->cr();
 500     BREAKPOINT;
 501   }
 502 
 503   if( PrintOpto ) {
 504     if (is_osr_compilation()) {
 505       tty->print("[OSR]%3d", _compile_id);
 506     } else {
 507       tty->print("%3d", _compile_id);
 508     }
 509   }
 510 #endif
 511 }
 512 
 513 
 514 //-----------------------init_scratch_buffer_blob------------------------------
 515 // Construct a temporary BufferBlob and cache it for this compile.
 516 void Compile::init_scratch_buffer_blob(int const_size) {
 517   // If there is already a scratch buffer blob allocated and the
 518   // constant section is big enough, use it.  Otherwise free the
 519   // current and allocate a new one.
 520   BufferBlob* blob = scratch_buffer_blob();
 521   if ((blob != NULL) && (const_size <= _scratch_const_size)) {
 522     // Use the current blob.
 523   } else {
 524     if (blob != NULL) {
 525       BufferBlob::free(blob);
 526     }
 527 
 528     ResourceMark rm;
 529     _scratch_const_size = const_size;
 530     int size = (MAX_inst_size + MAX_stubs_size + _scratch_const_size);
 531     blob = BufferBlob::create("Compile::scratch_buffer", size);
 532     // Record the buffer blob for next time.
 533     set_scratch_buffer_blob(blob);
 534     // Have we run out of code space?
 535     if (scratch_buffer_blob() == NULL) {
 536       // Let CompilerBroker disable further compilations.
 537       record_failure("Not enough space for scratch buffer in CodeCache");
 538       CompileBroker::handle_full_code_cache();
 539       return;
 540     }
 541   }
 542 
 543   // Initialize the relocation buffers
 544   relocInfo* locs_buf = (relocInfo*) blob->content_end() - MAX_locs_size;
 545   set_scratch_locs_memory(locs_buf);
 546 }
 547 
 548 
 549 //-----------------------scratch_emit_size-------------------------------------
 550 // Helper function that computes size by emitting code
 551 uint Compile::scratch_emit_size(const Node* n) {
 552   // Start scratch_emit_size section.
 553   set_in_scratch_emit_size(true);
 554 
 555   // Emit into a trash buffer and count bytes emitted.
 556   // This is a pretty expensive way to compute a size,
 557   // but it works well enough if seldom used.
 558   // All common fixed-size instructions are given a size
 559   // method by the AD file.
 560   // Note that the scratch buffer blob and locs memory are
 561   // allocated at the beginning of the compile task, and
 562   // may be shared by several calls to scratch_emit_size.
 563   // The allocation of the scratch buffer blob is particularly
 564   // expensive, since it has to grab the code cache lock.
 565   BufferBlob* blob = this->scratch_buffer_blob();
 566   assert(blob != NULL, "Initialize BufferBlob at start");
 567   assert(blob->size() > MAX_inst_size, "sanity");
 568   relocInfo* locs_buf = scratch_locs_memory();
 569   address blob_begin = blob->content_begin();
 570   address blob_end   = (address)locs_buf;
 571   assert(blob->content_contains(blob_end), "sanity");
 572   CodeBuffer buf(blob_begin, blob_end - blob_begin);
 573   buf.initialize_consts_size(_scratch_const_size);
 574   buf.initialize_stubs_size(MAX_stubs_size);
 575   assert(locs_buf != NULL, "sanity");
 576   int lsize = MAX_locs_size / 3;
 577   buf.consts()->initialize_shared_locs(&locs_buf[lsize * 0], lsize);
 578   buf.insts()->initialize_shared_locs( &locs_buf[lsize * 1], lsize);
 579   buf.stubs()->initialize_shared_locs( &locs_buf[lsize * 2], lsize);
 580 
 581   // Do the emission.
 582 
 583   Label fakeL; // Fake label for branch instructions.
 584   Label*   saveL = NULL;
 585   uint save_bnum = 0;
 586   bool is_branch = n->is_MachBranch();
 587   if (is_branch) {
 588     MacroAssembler masm(&buf);
 589     masm.bind(fakeL);
 590     n->as_MachBranch()->save_label(&saveL, &save_bnum);
 591     n->as_MachBranch()->label_set(&fakeL, 0);
 592   }
 593   n->emit(buf, this->regalloc());
 594   if (is_branch) // Restore label.
 595     n->as_MachBranch()->label_set(saveL, save_bnum);
 596 
 597   // End scratch_emit_size section.
 598   set_in_scratch_emit_size(false);
 599 
 600   return buf.insts_size();
 601 }
 602 
 603 
 604 // ============================================================================
 605 //------------------------------Compile standard-------------------------------
 606 debug_only( int Compile::_debug_idx = 100000; )
 607 
 608 // Compile a method.  entry_bci is -1 for normal compilations and indicates
 609 // the continuation bci for on stack replacement.
 610 
 611 
 612 Compile::Compile( ciEnv* ci_env, C2Compiler* compiler, ciMethod* target, int osr_bci,
 613                   bool subsume_loads, bool do_escape_analysis, bool eliminate_boxing )
 614                 : Phase(Compiler),
 615                   _env(ci_env),
 616                   _log(ci_env->log()),
 617                   _compile_id(ci_env->compile_id()),
 618                   _save_argument_registers(false),
 619                   _stub_name(NULL),
 620                   _stub_function(NULL),
 621                   _stub_entry_point(NULL),
 622                   _method(target),
 623                   _entry_bci(osr_bci),
 624                   _initial_gvn(NULL),
 625                   _for_igvn(NULL),
 626                   _warm_calls(NULL),
 627                   _subsume_loads(subsume_loads),
 628                   _do_escape_analysis(do_escape_analysis),
 629                   _eliminate_boxing(eliminate_boxing),
 630                   _failure_reason(NULL),
 631                   _code_buffer("Compile::Fill_buffer"),
 632                   _orig_pc_slot(0),
 633                   _orig_pc_slot_offset_in_bytes(0),
 634                   _has_method_handle_invokes(false),
 635                   _mach_constant_base_node(NULL),
 636                   _node_bundling_limit(0),
 637                   _node_bundling_base(NULL),
 638                   _java_calls(0),
 639                   _inner_loops(0),
 640                   _scratch_const_size(-1),
 641                   _in_scratch_emit_size(false),
 642                   _dead_node_list(comp_arena()),
 643                   _dead_node_count(0),
 644 #ifndef PRODUCT
 645                   _trace_opto_output(TraceOptoOutput || method()->has_option("TraceOptoOutput")),
 646                   _in_dump_cnt(0),
 647                   _printer(IdealGraphPrinter::printer()),
 648 #endif
 649                   _congraph(NULL),
 650                   _replay_inline_data(NULL),
 651                   _late_inlines(comp_arena(), 2, 0, NULL),
 652                   _string_late_inlines(comp_arena(), 2, 0, NULL),
 653                   _boxing_late_inlines(comp_arena(), 2, 0, NULL),
 654                   _late_inlines_pos(0),
 655                   _number_of_mh_late_inlines(0),
 656                   _inlining_progress(false),
 657                   _inlining_incrementally(false),
 658                   _print_inlining_list(NULL),
 659                   _print_inlining_stream(NULL),
 660                   _print_inlining_idx(0),
 661                   _print_inlining_output(NULL),
 662                   _interpreter_frame_size(0) {
 663   C = this;
 664 
 665   CompileWrapper cw(this);
 666 #ifndef PRODUCT
 667   if (TimeCompiler2) {
 668     tty->print(" ");
 669     target->holder()->name()->print();
 670     tty->print(".");
 671     target->print_short_name();
 672     tty->print("  ");
 673   }
 674   TraceTime t1("Total compilation time", &_t_totalCompilation, TimeCompiler, TimeCompiler2);
 675   TraceTime t2(NULL, &_t_methodCompilation, TimeCompiler, false);
 676   bool print_opto_assembly = PrintOptoAssembly || _method->has_option("PrintOptoAssembly");
 677   if (!print_opto_assembly) {
 678     bool print_assembly = (PrintAssembly || _method->should_print_assembly());
 679     if (print_assembly && !Disassembler::can_decode()) {
 680       tty->print_cr("PrintAssembly request changed to PrintOptoAssembly");
 681       print_opto_assembly = true;
 682     }
 683   }
 684   set_print_assembly(print_opto_assembly);
 685   set_parsed_irreducible_loop(false);
 686 
 687   if (method()->has_option("ReplayInline")) {
 688     _replay_inline_data = ciReplay::load_inline_data(method(), entry_bci(), ci_env->comp_level());
 689   }
 690 #endif
 691   set_print_inlining(PrintInlining || method()->has_option("PrintInlining") NOT_PRODUCT( || PrintOptoInlining));
 692   set_print_intrinsics(PrintIntrinsics || method()->has_option("PrintIntrinsics"));
 693   set_has_irreducible_loop(true); // conservative until build_loop_tree() reset it
 694 
 695   if (ProfileTraps RTM_OPT_ONLY( || UseRTMLocking )) {
 696     // Make sure the method being compiled gets its own MDO,
 697     // so we can at least track the decompile_count().
 698     // Need MDO to record RTM code generation state.
 699     method()->ensure_method_data();
 700   }
 701 
 702   Init(::AliasLevel);
 703 
 704 
 705   print_compile_messages();
 706 
 707   _ilt = InlineTree::build_inline_tree_root();
 708 
 709   // Even if NO memory addresses are used, MergeMem nodes must have at least 1 slice
 710   assert(num_alias_types() >= AliasIdxRaw, "");
 711 
 712 #define MINIMUM_NODE_HASH  1023
 713   // Node list that Iterative GVN will start with
 714   Unique_Node_List for_igvn(comp_arena());
 715   set_for_igvn(&for_igvn);
 716 
 717   // GVN that will be run immediately on new nodes
 718   uint estimated_size = method()->code_size()*4+64;
 719   estimated_size = (estimated_size < MINIMUM_NODE_HASH ? MINIMUM_NODE_HASH : estimated_size);
 720   PhaseGVN gvn(node_arena(), estimated_size);
 721   set_initial_gvn(&gvn);
 722 
 723   print_inlining_init();
 724   { // Scope for timing the parser
 725     TracePhase t3("parse", &_t_parser, true);
 726 
 727     // Put top into the hash table ASAP.
 728     initial_gvn()->transform_no_reclaim(top());
 729 
 730     // Set up tf(), start(), and find a CallGenerator.
 731     CallGenerator* cg = NULL;
 732     if (is_osr_compilation()) {
 733       const TypeTuple *domain = StartOSRNode::osr_domain();
 734       const TypeTuple *range = TypeTuple::make_range(method()->signature());
 735       init_tf(TypeFunc::make(domain, range));
 736       StartNode* s = new StartOSRNode(root(), domain);
 737       initial_gvn()->set_type_bottom(s);
 738       init_start(s);
 739       cg = CallGenerator::for_osr(method(), entry_bci());
 740     } else {
 741       // Normal case.
 742       init_tf(TypeFunc::make(method()));
 743       StartNode* s = new StartNode(root(), tf()->domain());
 744       initial_gvn()->set_type_bottom(s);
 745       init_start(s);
 746       if (method()->intrinsic_id() == vmIntrinsics::_Reference_get && UseG1GC) {
 747         // With java.lang.ref.reference.get() we must go through the
 748         // intrinsic when G1 is enabled - even when get() is the root
 749         // method of the compile - so that, if necessary, the value in
 750         // the referent field of the reference object gets recorded by
 751         // the pre-barrier code.
 752         // Specifically, if G1 is enabled, the value in the referent
 753         // field is recorded by the G1 SATB pre barrier. This will
 754         // result in the referent being marked live and the reference
 755         // object removed from the list of discovered references during
 756         // reference processing.
 757         cg = find_intrinsic(method(), false);
 758       }
 759       if (cg == NULL) {
 760         float past_uses = method()->interpreter_invocation_count();
 761         float expected_uses = past_uses;
 762         cg = CallGenerator::for_inline(method(), expected_uses);
 763       }
 764     }
 765     if (failing())  return;
 766     if (cg == NULL) {
 767       record_method_not_compilable_all_tiers("cannot parse method");
 768       return;
 769     }
 770     JVMState* jvms = build_start_state(start(), tf());
 771     if ((jvms = cg->generate(jvms)) == NULL) {
 772       record_method_not_compilable("method parse failed");
 773       return;
 774     }
 775     GraphKit kit(jvms);
 776 
 777     if (!kit.stopped()) {
 778       // Accept return values, and transfer control we know not where.
 779       // This is done by a special, unique ReturnNode bound to root.
 780       return_values(kit.jvms());
 781     }
 782 
 783     if (kit.has_exceptions()) {
 784       // Any exceptions that escape from this call must be rethrown
 785       // to whatever caller is dynamically above us on the stack.
 786       // This is done by a special, unique RethrowNode bound to root.
 787       rethrow_exceptions(kit.transfer_exceptions_into_jvms());
 788     }
 789 
 790     assert(IncrementalInline || (_late_inlines.length() == 0 && !has_mh_late_inlines()), "incremental inlining is off");
 791 
 792     if (_late_inlines.length() == 0 && !has_mh_late_inlines() && !failing() && has_stringbuilder()) {
 793       inline_string_calls(true);
 794     }
 795 
 796     if (failing())  return;
 797 
 798     print_method(PHASE_BEFORE_REMOVEUSELESS, 3);
 799 
 800     // Remove clutter produced by parsing.
 801     if (!failing()) {
 802       ResourceMark rm;
 803       PhaseRemoveUseless pru(initial_gvn(), &for_igvn);
 804     }
 805   }
 806 
 807   // Note:  Large methods are capped off in do_one_bytecode().
 808   if (failing())  return;
 809 
 810   // After parsing, node notes are no longer automagic.
 811   // They must be propagated by register_new_node_with_optimizer(),
 812   // clone(), or the like.
 813   set_default_node_notes(NULL);
 814 
 815   for (;;) {
 816     int successes = Inline_Warm();
 817     if (failing())  return;
 818     if (successes == 0)  break;
 819   }
 820 
 821   // Drain the list.
 822   Finish_Warm();
 823 #ifndef PRODUCT
 824   if (_printer) {
 825     _printer->print_inlining(this);
 826   }
 827 #endif
 828 
 829   if (failing())  return;
 830   NOT_PRODUCT( verify_graph_edges(); )
 831 
 832   // Now optimize
 833   Optimize();
 834   if (failing())  return;
 835   NOT_PRODUCT( verify_graph_edges(); )
 836 
 837 #ifndef PRODUCT
 838   if (PrintIdeal) {
 839     ttyLocker ttyl;  // keep the following output all in one block
 840     // This output goes directly to the tty, not the compiler log.
 841     // To enable tools to match it up with the compilation activity,
 842     // be sure to tag this tty output with the compile ID.
 843     if (xtty != NULL) {
 844       xtty->head("ideal compile_id='%d'%s", compile_id(),
 845                  is_osr_compilation()    ? " compile_kind='osr'" :
 846                  "");
 847     }
 848     root()->dump(9999);
 849     if (xtty != NULL) {
 850       xtty->tail("ideal");
 851     }
 852   }
 853 #endif
 854 
 855   NOT_PRODUCT( verify_barriers(); )
 856 
 857   // Dump compilation data to replay it.
 858   if (method()->has_option("DumpReplay")) {
 859     env()->dump_replay_data(_compile_id);
 860   }
 861   if (method()->has_option("DumpInline") && (ilt() != NULL)) {
 862     env()->dump_inline_data(_compile_id);
 863   }
 864 
 865   // Now that we know the size of all the monitors we can add a fixed slot
 866   // for the original deopt pc.
 867 
 868   _orig_pc_slot =  fixed_slots();
 869   int next_slot = _orig_pc_slot + (sizeof(address) / VMRegImpl::stack_slot_size);
 870   set_fixed_slots(next_slot);
 871 
 872   // Compute when to use implicit null checks. Used by matching trap based
 873   // nodes and NullCheck optimization.
 874   set_allowed_deopt_reasons();
 875 
 876   // Now generate code
 877   Code_Gen();
 878   if (failing())  return;
 879 
 880   // Check if we want to skip execution of all compiled code.
 881   {
 882 #ifndef PRODUCT
 883     if (OptoNoExecute) {
 884       record_method_not_compilable("+OptoNoExecute");  // Flag as failed
 885       return;
 886     }
 887     TracePhase t2("install_code", &_t_registerMethod, TimeCompiler);
 888 #endif
 889 
 890     if (is_osr_compilation()) {
 891       _code_offsets.set_value(CodeOffsets::Verified_Entry, 0);
 892       _code_offsets.set_value(CodeOffsets::OSR_Entry, _first_block_size);
 893     } else {
 894       _code_offsets.set_value(CodeOffsets::Verified_Entry, _first_block_size);
 895       _code_offsets.set_value(CodeOffsets::OSR_Entry, 0);
 896     }
 897 
 898     env()->register_method(_method, _entry_bci,
 899                            &_code_offsets,
 900                            _orig_pc_slot_offset_in_bytes,
 901                            code_buffer(),
 902                            frame_size_in_words(), _oop_map_set,
 903                            &_handler_table, &_inc_table,
 904                            compiler,
 905                            env()->comp_level(),
 906                            has_unsafe_access(),
 907                            SharedRuntime::is_wide_vector(max_vector_size()),
 908                            rtm_state()
 909                            );
 910 
 911     if (log() != NULL) // Print code cache state into compiler log
 912       log()->code_cache_state();
 913   }
 914 }
 915 
 916 //------------------------------Compile----------------------------------------
 917 // Compile a runtime stub
 918 Compile::Compile( ciEnv* ci_env,
 919                   TypeFunc_generator generator,
 920                   address stub_function,
 921                   const char *stub_name,
 922                   int is_fancy_jump,
 923                   bool pass_tls,
 924                   bool save_arg_registers,
 925                   bool return_pc )
 926   : Phase(Compiler),
 927     _env(ci_env),
 928     _log(ci_env->log()),
 929     _compile_id(0),
 930     _save_argument_registers(save_arg_registers),
 931     _method(NULL),
 932     _stub_name(stub_name),
 933     _stub_function(stub_function),
 934     _stub_entry_point(NULL),
 935     _entry_bci(InvocationEntryBci),
 936     _initial_gvn(NULL),
 937     _for_igvn(NULL),
 938     _warm_calls(NULL),
 939     _orig_pc_slot(0),
 940     _orig_pc_slot_offset_in_bytes(0),
 941     _subsume_loads(true),
 942     _do_escape_analysis(false),
 943     _eliminate_boxing(false),
 944     _failure_reason(NULL),
 945     _code_buffer("Compile::Fill_buffer"),
 946     _has_method_handle_invokes(false),
 947     _mach_constant_base_node(NULL),
 948     _node_bundling_limit(0),
 949     _node_bundling_base(NULL),
 950     _java_calls(0),
 951     _inner_loops(0),
 952 #ifndef PRODUCT
 953     _trace_opto_output(TraceOptoOutput),
 954     _in_dump_cnt(0),
 955     _printer(NULL),
 956 #endif
 957     _dead_node_list(comp_arena()),
 958     _dead_node_count(0),
 959     _congraph(NULL),
 960     _replay_inline_data(NULL),
 961     _number_of_mh_late_inlines(0),
 962     _inlining_progress(false),
 963     _inlining_incrementally(false),
 964     _print_inlining_list(NULL),
 965     _print_inlining_stream(NULL),
 966     _print_inlining_idx(0),
 967     _print_inlining_output(NULL),
 968     _allowed_reasons(0),
 969     _interpreter_frame_size(0) {
 970   C = this;
 971 
 972 #ifndef PRODUCT
 973   TraceTime t1(NULL, &_t_totalCompilation, TimeCompiler, false);
 974   TraceTime t2(NULL, &_t_stubCompilation, TimeCompiler, false);
 975   set_print_assembly(PrintFrameConverterAssembly);
 976   set_parsed_irreducible_loop(false);
 977 #endif
 978   set_has_irreducible_loop(false); // no loops
 979 
 980   CompileWrapper cw(this);
 981   Init(/*AliasLevel=*/ 0);
 982   init_tf((*generator)());
 983 
 984   {
 985     // The following is a dummy for the sake of GraphKit::gen_stub
 986     Unique_Node_List for_igvn(comp_arena());
 987     set_for_igvn(&for_igvn);  // not used, but some GraphKit guys push on this
 988     PhaseGVN gvn(Thread::current()->resource_area(),255);
 989     set_initial_gvn(&gvn);    // not significant, but GraphKit guys use it pervasively
 990     gvn.transform_no_reclaim(top());
 991 
 992     GraphKit kit;
 993     kit.gen_stub(stub_function, stub_name, is_fancy_jump, pass_tls, return_pc);
 994   }
 995 
 996   NOT_PRODUCT( verify_graph_edges(); )
 997   Code_Gen();
 998   if (failing())  return;
 999 
1000 
1001   // Entry point will be accessed using compile->stub_entry_point();
1002   if (code_buffer() == NULL) {
1003     Matcher::soft_match_failure();
1004   } else {
1005     if (PrintAssembly && (WizardMode || Verbose))
1006       tty->print_cr("### Stub::%s", stub_name);
1007 
1008     if (!failing()) {
1009       assert(_fixed_slots == 0, "no fixed slots used for runtime stubs");
1010 
1011       // Make the NMethod
1012       // For now we mark the frame as never safe for profile stackwalking
1013       RuntimeStub *rs = RuntimeStub::new_runtime_stub(stub_name,
1014                                                       code_buffer(),
1015                                                       CodeOffsets::frame_never_safe,
1016                                                       // _code_offsets.value(CodeOffsets::Frame_Complete),
1017                                                       frame_size_in_words(),
1018                                                       _oop_map_set,
1019                                                       save_arg_registers);
1020       assert(rs != NULL && rs->is_runtime_stub(), "sanity check");
1021 
1022       _stub_entry_point = rs->entry_point();
1023     }
1024   }
1025 }
1026 
1027 //------------------------------Init-------------------------------------------
1028 // Prepare for a single compilation
1029 void Compile::Init(int aliaslevel) {
1030   _unique  = 0;
1031   _regalloc = NULL;
1032 
1033   _tf      = NULL;  // filled in later
1034   _top     = NULL;  // cached later
1035   _matcher = NULL;  // filled in later
1036   _cfg     = NULL;  // filled in later
1037 
1038   set_24_bit_selection_and_mode(Use24BitFP, false);
1039 
1040   _node_note_array = NULL;
1041   _default_node_notes = NULL;
1042   DEBUG_ONLY( _modified_nodes = NULL; ) // Used in Optimize()
1043 
1044   _immutable_memory = NULL; // filled in at first inquiry
1045 
1046   // Globally visible Nodes
1047   // First set TOP to NULL to give safe behavior during creation of RootNode
1048   set_cached_top_node(NULL);
1049   set_root(new RootNode());
1050   // Now that you have a Root to point to, create the real TOP
1051   set_cached_top_node( new ConNode(Type::TOP) );
1052   set_recent_alloc(NULL, NULL);
1053 
1054   // Create Debug Information Recorder to record scopes, oopmaps, etc.
1055   env()->set_oop_recorder(new OopRecorder(env()->arena()));
1056   env()->set_debug_info(new DebugInformationRecorder(env()->oop_recorder()));
1057   env()->set_dependencies(new Dependencies(env()));
1058 
1059   _fixed_slots = 0;
1060   set_has_split_ifs(false);
1061   set_has_loops(has_method() && method()->has_loops()); // first approximation
1062   set_has_stringbuilder(false);
1063   set_has_boxed_value(false);
1064   _trap_can_recompile = false;  // no traps emitted yet
1065   _major_progress = true; // start out assuming good things will happen
1066   set_has_unsafe_access(false);
1067   set_max_vector_size(0);
1068   Copy::zero_to_bytes(_trap_hist, sizeof(_trap_hist));
1069   set_decompile_count(0);
1070 
1071   set_do_freq_based_layout(BlockLayoutByFrequency || method_has_option("BlockLayoutByFrequency"));
1072   set_num_loop_opts(LoopOptsCount);
1073   set_do_inlining(Inline);
1074   set_max_inline_size(MaxInlineSize);
1075   set_freq_inline_size(FreqInlineSize);
1076   set_do_scheduling(OptoScheduling);
1077   set_do_count_invocations(false);
1078   set_do_method_data_update(false);
1079   set_age_code(has_method() && method()->profile_aging());
1080   set_rtm_state(NoRTM); // No RTM lock eliding by default
1081 #if INCLUDE_RTM_OPT
1082   if (UseRTMLocking && has_method() && (method()->method_data_or_null() != NULL)) {
1083     int rtm_state = method()->method_data()->rtm_state();
1084     if (method_has_option("NoRTMLockEliding") || ((rtm_state & NoRTM) != 0)) {
1085       // Don't generate RTM lock eliding code.
1086       set_rtm_state(NoRTM);
1087     } else if (method_has_option("UseRTMLockEliding") || ((rtm_state & UseRTM) != 0) || !UseRTMDeopt) {
1088       // Generate RTM lock eliding code without abort ratio calculation code.
1089       set_rtm_state(UseRTM);
1090     } else if (UseRTMDeopt) {
1091       // Generate RTM lock eliding code and include abort ratio calculation
1092       // code if UseRTMDeopt is on.
1093       set_rtm_state(ProfileRTM);
1094     }
1095   }
1096 #endif
1097   if (debug_info()->recording_non_safepoints()) {
1098     set_node_note_array(new(comp_arena()) GrowableArray<Node_Notes*>
1099                         (comp_arena(), 8, 0, NULL));
1100     set_default_node_notes(Node_Notes::make(this));
1101   }
1102 
1103   // // -- Initialize types before each compile --
1104   // // Update cached type information
1105   // if( _method && _method->constants() )
1106   //   Type::update_loaded_types(_method, _method->constants());
1107 
1108   // Init alias_type map.
1109   if (!_do_escape_analysis && aliaslevel == 3)
1110     aliaslevel = 2;  // No unique types without escape analysis
1111   _AliasLevel = aliaslevel;
1112   const int grow_ats = 16;
1113   _max_alias_types = grow_ats;
1114   _alias_types   = NEW_ARENA_ARRAY(comp_arena(), AliasType*, grow_ats);
1115   AliasType* ats = NEW_ARENA_ARRAY(comp_arena(), AliasType,  grow_ats);
1116   Copy::zero_to_bytes(ats, sizeof(AliasType)*grow_ats);
1117   {
1118     for (int i = 0; i < grow_ats; i++)  _alias_types[i] = &ats[i];
1119   }
1120   // Initialize the first few types.
1121   _alias_types[AliasIdxTop]->Init(AliasIdxTop, NULL);
1122   _alias_types[AliasIdxBot]->Init(AliasIdxBot, TypePtr::BOTTOM);
1123   _alias_types[AliasIdxRaw]->Init(AliasIdxRaw, TypeRawPtr::BOTTOM);
1124   _num_alias_types = AliasIdxRaw+1;
1125   // Zero out the alias type cache.
1126   Copy::zero_to_bytes(_alias_cache, sizeof(_alias_cache));
1127   // A NULL adr_type hits in the cache right away.  Preload the right answer.
1128   probe_alias_cache(NULL)->_index = AliasIdxTop;
1129 
1130   _intrinsics = NULL;
1131   _macro_nodes = new(comp_arena()) GrowableArray<Node*>(comp_arena(), 8,  0, NULL);
1132   _predicate_opaqs = new(comp_arena()) GrowableArray<Node*>(comp_arena(), 8,  0, NULL);
1133   _expensive_nodes = new(comp_arena()) GrowableArray<Node*>(comp_arena(), 8,  0, NULL);
1134   register_library_intrinsics();
1135 }
1136 
1137 //---------------------------init_start----------------------------------------
1138 // Install the StartNode on this compile object.
1139 void Compile::init_start(StartNode* s) {
1140   if (failing())
1141     return; // already failing
1142   assert(s == start(), "");
1143 }
1144 
1145 StartNode* Compile::start() const {
1146   assert(!failing(), "");
1147   for (DUIterator_Fast imax, i = root()->fast_outs(imax); i < imax; i++) {
1148     Node* start = root()->fast_out(i);
1149     if( start->is_Start() )
1150       return start->as_Start();
1151   }
1152   fatal("Did not find Start node!");
1153   return NULL;
1154 }
1155 
1156 //-------------------------------immutable_memory-------------------------------------
1157 // Access immutable memory
1158 Node* Compile::immutable_memory() {
1159   if (_immutable_memory != NULL) {
1160     return _immutable_memory;
1161   }
1162   StartNode* s = start();
1163   for (DUIterator_Fast imax, i = s->fast_outs(imax); true; i++) {
1164     Node *p = s->fast_out(i);
1165     if (p != s && p->as_Proj()->_con == TypeFunc::Memory) {
1166       _immutable_memory = p;
1167       return _immutable_memory;
1168     }
1169   }
1170   ShouldNotReachHere();
1171   return NULL;
1172 }
1173 
1174 //----------------------set_cached_top_node------------------------------------
1175 // Install the cached top node, and make sure Node::is_top works correctly.
1176 void Compile::set_cached_top_node(Node* tn) {
1177   if (tn != NULL)  verify_top(tn);
1178   Node* old_top = _top;
1179   _top = tn;
1180   // Calling Node::setup_is_top allows the nodes the chance to adjust
1181   // their _out arrays.
1182   if (_top != NULL)     _top->setup_is_top();
1183   if (old_top != NULL)  old_top->setup_is_top();
1184   assert(_top == NULL || top()->is_top(), "");
1185 }
1186 
1187 #ifdef ASSERT
1188 uint Compile::count_live_nodes_by_graph_walk() {
1189   Unique_Node_List useful(comp_arena());
1190   // Get useful node list by walking the graph.
1191   identify_useful_nodes(useful);
1192   return useful.size();
1193 }
1194 
1195 void Compile::print_missing_nodes() {
1196 
1197   // Return if CompileLog is NULL and PrintIdealNodeCount is false.
1198   if ((_log == NULL) && (! PrintIdealNodeCount)) {
1199     return;
1200   }
1201 
1202   // This is an expensive function. It is executed only when the user
1203   // specifies VerifyIdealNodeCount option or otherwise knows the
1204   // additional work that needs to be done to identify reachable nodes
1205   // by walking the flow graph and find the missing ones using
1206   // _dead_node_list.
1207 
1208   Unique_Node_List useful(comp_arena());
1209   // Get useful node list by walking the graph.
1210   identify_useful_nodes(useful);
1211 
1212   uint l_nodes = C->live_nodes();
1213   uint l_nodes_by_walk = useful.size();
1214 
1215   if (l_nodes != l_nodes_by_walk) {
1216     if (_log != NULL) {
1217       _log->begin_head("mismatched_nodes count='%d'", abs((int) (l_nodes - l_nodes_by_walk)));
1218       _log->stamp();
1219       _log->end_head();
1220     }
1221     VectorSet& useful_member_set = useful.member_set();
1222     int last_idx = l_nodes_by_walk;
1223     for (int i = 0; i < last_idx; i++) {
1224       if (useful_member_set.test(i)) {
1225         if (_dead_node_list.test(i)) {
1226           if (_log != NULL) {
1227             _log->elem("mismatched_node_info node_idx='%d' type='both live and dead'", i);
1228           }
1229           if (PrintIdealNodeCount) {
1230             // Print the log message to tty
1231               tty->print_cr("mismatched_node idx='%d' both live and dead'", i);
1232               useful.at(i)->dump();
1233           }
1234         }
1235       }
1236       else if (! _dead_node_list.test(i)) {
1237         if (_log != NULL) {
1238           _log->elem("mismatched_node_info node_idx='%d' type='neither live nor dead'", i);
1239         }
1240         if (PrintIdealNodeCount) {
1241           // Print the log message to tty
1242           tty->print_cr("mismatched_node idx='%d' type='neither live nor dead'", i);
1243         }
1244       }
1245     }
1246     if (_log != NULL) {
1247       _log->tail("mismatched_nodes");
1248     }
1249   }
1250 }
1251 void Compile::record_modified_node(Node* n) {
1252   if (_modified_nodes != NULL && !_inlining_incrementally &&
1253       n->outcnt() != 0 && !n->is_Con()) {
1254     _modified_nodes->push(n);
1255   }
1256 }
1257 
1258 void Compile::remove_modified_node(Node* n) {
1259   if (_modified_nodes != NULL) {
1260     _modified_nodes->remove(n);
1261   }
1262 }
1263 #endif
1264 
1265 #ifndef PRODUCT
1266 void Compile::verify_top(Node* tn) const {
1267   if (tn != NULL) {
1268     assert(tn->is_Con(), "top node must be a constant");
1269     assert(((ConNode*)tn)->type() == Type::TOP, "top node must have correct type");
1270     assert(tn->in(0) != NULL, "must have live top node");
1271   }
1272 }
1273 #endif
1274 
1275 
1276 ///-------------------Managing Per-Node Debug & Profile Info-------------------
1277 
1278 void Compile::grow_node_notes(GrowableArray<Node_Notes*>* arr, int grow_by) {
1279   guarantee(arr != NULL, "");
1280   int num_blocks = arr->length();
1281   if (grow_by < num_blocks)  grow_by = num_blocks;
1282   int num_notes = grow_by * _node_notes_block_size;
1283   Node_Notes* notes = NEW_ARENA_ARRAY(node_arena(), Node_Notes, num_notes);
1284   Copy::zero_to_bytes(notes, num_notes * sizeof(Node_Notes));
1285   while (num_notes > 0) {
1286     arr->append(notes);
1287     notes     += _node_notes_block_size;
1288     num_notes -= _node_notes_block_size;
1289   }
1290   assert(num_notes == 0, "exact multiple, please");
1291 }
1292 
1293 bool Compile::copy_node_notes_to(Node* dest, Node* source) {
1294   if (source == NULL || dest == NULL)  return false;
1295 
1296   if (dest->is_Con())
1297     return false;               // Do not push debug info onto constants.
1298 
1299 #ifdef ASSERT
1300   // Leave a bread crumb trail pointing to the original node:
1301   if (dest != NULL && dest != source && dest->debug_orig() == NULL) {
1302     dest->set_debug_orig(source);
1303   }
1304 #endif
1305 
1306   if (node_note_array() == NULL)
1307     return false;               // Not collecting any notes now.
1308 
1309   // This is a copy onto a pre-existing node, which may already have notes.
1310   // If both nodes have notes, do not overwrite any pre-existing notes.
1311   Node_Notes* source_notes = node_notes_at(source->_idx);
1312   if (source_notes == NULL || source_notes->is_clear())  return false;
1313   Node_Notes* dest_notes   = node_notes_at(dest->_idx);
1314   if (dest_notes == NULL || dest_notes->is_clear()) {
1315     return set_node_notes_at(dest->_idx, source_notes);
1316   }
1317 
1318   Node_Notes merged_notes = (*source_notes);
1319   // The order of operations here ensures that dest notes will win...
1320   merged_notes.update_from(dest_notes);
1321   return set_node_notes_at(dest->_idx, &merged_notes);
1322 }
1323 
1324 
1325 //--------------------------allow_range_check_smearing-------------------------
1326 // Gating condition for coalescing similar range checks.
1327 // Sometimes we try 'speculatively' replacing a series of a range checks by a
1328 // single covering check that is at least as strong as any of them.
1329 // If the optimization succeeds, the simplified (strengthened) range check
1330 // will always succeed.  If it fails, we will deopt, and then give up
1331 // on the optimization.
1332 bool Compile::allow_range_check_smearing() const {
1333   // If this method has already thrown a range-check,
1334   // assume it was because we already tried range smearing
1335   // and it failed.
1336   uint already_trapped = trap_count(Deoptimization::Reason_range_check);
1337   return !already_trapped;
1338 }
1339 
1340 
1341 //------------------------------flatten_alias_type-----------------------------
1342 const TypePtr *Compile::flatten_alias_type( const TypePtr *tj ) const {
1343   int offset = tj->offset();
1344   TypePtr::PTR ptr = tj->ptr();
1345 
1346   // Known instance (scalarizable allocation) alias only with itself.
1347   bool is_known_inst = tj->isa_oopptr() != NULL &&
1348                        tj->is_oopptr()->is_known_instance();
1349 
1350   // Process weird unsafe references.
1351   if (offset == Type::OffsetBot && (tj->isa_instptr() /*|| tj->isa_klassptr()*/)) {
1352     assert(InlineUnsafeOps, "indeterminate pointers come only from unsafe ops");
1353     assert(!is_known_inst, "scalarizable allocation should not have unsafe references");
1354     tj = TypeOopPtr::BOTTOM;
1355     ptr = tj->ptr();
1356     offset = tj->offset();
1357   }
1358 
1359   // Array pointers need some flattening
1360   const TypeAryPtr *ta = tj->isa_aryptr();
1361   if (ta && ta->is_stable()) {
1362     // Erase stability property for alias analysis.
1363     tj = ta = ta->cast_to_stable(false);
1364   }
1365   if( ta && is_known_inst ) {
1366     if ( offset != Type::OffsetBot &&
1367          offset > arrayOopDesc::length_offset_in_bytes() ) {
1368       offset = Type::OffsetBot; // Flatten constant access into array body only
1369       tj = ta = TypeAryPtr::make(ptr, ta->ary(), ta->klass(), true, offset, ta->instance_id());
1370     }
1371   } else if( ta && _AliasLevel >= 2 ) {
1372     // For arrays indexed by constant indices, we flatten the alias
1373     // space to include all of the array body.  Only the header, klass
1374     // and array length can be accessed un-aliased.
1375     if( offset != Type::OffsetBot ) {
1376       if( ta->const_oop() ) { // MethodData* or Method*
1377         offset = Type::OffsetBot;   // Flatten constant access into array body
1378         tj = ta = TypeAryPtr::make(ptr,ta->const_oop(),ta->ary(),ta->klass(),false,offset);
1379       } else if( offset == arrayOopDesc::length_offset_in_bytes() ) {
1380         // range is OK as-is.
1381         tj = ta = TypeAryPtr::RANGE;
1382       } else if( offset == oopDesc::klass_offset_in_bytes() ) {
1383         tj = TypeInstPtr::KLASS; // all klass loads look alike
1384         ta = TypeAryPtr::RANGE; // generic ignored junk
1385         ptr = TypePtr::BotPTR;
1386       } else if( offset == oopDesc::mark_offset_in_bytes() ) {
1387         tj = TypeInstPtr::MARK;
1388         ta = TypeAryPtr::RANGE; // generic ignored junk
1389         ptr = TypePtr::BotPTR;
1390       } else {                  // Random constant offset into array body
1391         offset = Type::OffsetBot;   // Flatten constant access into array body
1392         tj = ta = TypeAryPtr::make(ptr,ta->ary(),ta->klass(),false,offset);
1393       }
1394     }
1395     // Arrays of fixed size alias with arrays of unknown size.
1396     if (ta->size() != TypeInt::POS) {
1397       const TypeAry *tary = TypeAry::make(ta->elem(), TypeInt::POS);
1398       tj = ta = TypeAryPtr::make(ptr,ta->const_oop(),tary,ta->klass(),false,offset);
1399     }
1400     // Arrays of known objects become arrays of unknown objects.
1401     if (ta->elem()->isa_narrowoop() && ta->elem() != TypeNarrowOop::BOTTOM) {
1402       const TypeAry *tary = TypeAry::make(TypeNarrowOop::BOTTOM, ta->size());
1403       tj = ta = TypeAryPtr::make(ptr,ta->const_oop(),tary,NULL,false,offset);
1404     }
1405     if (ta->elem()->isa_oopptr() && ta->elem() != TypeInstPtr::BOTTOM) {
1406       const TypeAry *tary = TypeAry::make(TypeInstPtr::BOTTOM, ta->size());
1407       tj = ta = TypeAryPtr::make(ptr,ta->const_oop(),tary,NULL,false,offset);
1408     }
1409     // Arrays of bytes and of booleans both use 'bastore' and 'baload' so
1410     // cannot be distinguished by bytecode alone.
1411     if (ta->elem() == TypeInt::BOOL) {
1412       const TypeAry *tary = TypeAry::make(TypeInt::BYTE, ta->size());
1413       ciKlass* aklass = ciTypeArrayKlass::make(T_BYTE);
1414       tj = ta = TypeAryPtr::make(ptr,ta->const_oop(),tary,aklass,false,offset);
1415     }
1416     // During the 2nd round of IterGVN, NotNull castings are removed.
1417     // Make sure the Bottom and NotNull variants alias the same.
1418     // Also, make sure exact and non-exact variants alias the same.
1419     if (ptr == TypePtr::NotNull || ta->klass_is_exact() || ta->speculative() != NULL) {
1420       tj = ta = TypeAryPtr::make(TypePtr::BotPTR,ta->ary(),ta->klass(),false,offset);
1421     }
1422   }
1423 
1424   // Oop pointers need some flattening
1425   const TypeInstPtr *to = tj->isa_instptr();
1426   if( to && _AliasLevel >= 2 && to != TypeOopPtr::BOTTOM ) {
1427     ciInstanceKlass *k = to->klass()->as_instance_klass();
1428     if( ptr == TypePtr::Constant ) {
1429       if (to->klass() != ciEnv::current()->Class_klass() ||
1430           offset < k->size_helper() * wordSize) {
1431         // No constant oop pointers (such as Strings); they alias with
1432         // unknown strings.
1433         assert(!is_known_inst, "not scalarizable allocation");
1434         tj = to = TypeInstPtr::make(TypePtr::BotPTR,to->klass(),false,0,offset);
1435       }
1436     } else if( is_known_inst ) {
1437       tj = to; // Keep NotNull and klass_is_exact for instance type
1438     } else if( ptr == TypePtr::NotNull || to->klass_is_exact() ) {
1439       // During the 2nd round of IterGVN, NotNull castings are removed.
1440       // Make sure the Bottom and NotNull variants alias the same.
1441       // Also, make sure exact and non-exact variants alias the same.
1442       tj = to = TypeInstPtr::make(TypePtr::BotPTR,to->klass(),false,0,offset);
1443     }
1444     if (to->speculative() != NULL) {
1445       tj = to = TypeInstPtr::make(to->ptr(),to->klass(),to->klass_is_exact(),to->const_oop(),to->offset(), to->instance_id());
1446     }
1447     // Canonicalize the holder of this field
1448     if (offset >= 0 && offset < instanceOopDesc::base_offset_in_bytes()) {
1449       // First handle header references such as a LoadKlassNode, even if the
1450       // object's klass is unloaded at compile time (4965979).
1451       if (!is_known_inst) { // Do it only for non-instance types
1452         tj = to = TypeInstPtr::make(TypePtr::BotPTR, env()->Object_klass(), false, NULL, offset);
1453       }
1454     } else if (offset < 0 || offset >= k->size_helper() * wordSize) {
1455       // Static fields are in the space above the normal instance
1456       // fields in the java.lang.Class instance.
1457       if (to->klass() != ciEnv::current()->Class_klass()) {
1458         to = NULL;
1459         tj = TypeOopPtr::BOTTOM;
1460         offset = tj->offset();
1461       }
1462     } else {
1463       ciInstanceKlass *canonical_holder = k->get_canonical_holder(offset);
1464       if (!k->equals(canonical_holder) || tj->offset() != offset) {
1465         if( is_known_inst ) {
1466           tj = to = TypeInstPtr::make(to->ptr(), canonical_holder, true, NULL, offset, to->instance_id());
1467         } else {
1468           tj = to = TypeInstPtr::make(to->ptr(), canonical_holder, false, NULL, offset);
1469         }
1470       }
1471     }
1472   }
1473 
1474   // Klass pointers to object array klasses need some flattening
1475   const TypeKlassPtr *tk = tj->isa_klassptr();
1476   if( tk ) {
1477     // If we are referencing a field within a Klass, we need
1478     // to assume the worst case of an Object.  Both exact and
1479     // inexact types must flatten to the same alias class so
1480     // use NotNull as the PTR.
1481     if ( offset == Type::OffsetBot || (offset >= 0 && (size_t)offset < sizeof(Klass)) ) {
1482 
1483       tj = tk = TypeKlassPtr::make(TypePtr::NotNull,
1484                                    TypeKlassPtr::OBJECT->klass(),
1485                                    offset);
1486     }
1487 
1488     ciKlass* klass = tk->klass();
1489     if( klass->is_obj_array_klass() ) {
1490       ciKlass* k = TypeAryPtr::OOPS->klass();
1491       if( !k || !k->is_loaded() )                  // Only fails for some -Xcomp runs
1492         k = TypeInstPtr::BOTTOM->klass();
1493       tj = tk = TypeKlassPtr::make( TypePtr::NotNull, k, offset );
1494     }
1495 
1496     // Check for precise loads from the primary supertype array and force them
1497     // to the supertype cache alias index.  Check for generic array loads from
1498     // the primary supertype array and also force them to the supertype cache
1499     // alias index.  Since the same load can reach both, we need to merge
1500     // these 2 disparate memories into the same alias class.  Since the
1501     // primary supertype array is read-only, there's no chance of confusion
1502     // where we bypass an array load and an array store.
1503     int primary_supers_offset = in_bytes(Klass::primary_supers_offset());
1504     if (offset == Type::OffsetBot ||
1505         (offset >= primary_supers_offset &&
1506          offset < (int)(primary_supers_offset + Klass::primary_super_limit() * wordSize)) ||
1507         offset == (int)in_bytes(Klass::secondary_super_cache_offset())) {
1508       offset = in_bytes(Klass::secondary_super_cache_offset());
1509       tj = tk = TypeKlassPtr::make( TypePtr::NotNull, tk->klass(), offset );
1510     }
1511   }
1512 
1513   // Flatten all Raw pointers together.
1514   if (tj->base() == Type::RawPtr)
1515     tj = TypeRawPtr::BOTTOM;
1516 
1517   if (tj->base() == Type::AnyPtr)
1518     tj = TypePtr::BOTTOM;      // An error, which the caller must check for.
1519 
1520   // Flatten all to bottom for now
1521   switch( _AliasLevel ) {
1522   case 0:
1523     tj = TypePtr::BOTTOM;
1524     break;
1525   case 1:                       // Flatten to: oop, static, field or array
1526     switch (tj->base()) {
1527     //case Type::AryPtr: tj = TypeAryPtr::RANGE;    break;
1528     case Type::RawPtr:   tj = TypeRawPtr::BOTTOM;   break;
1529     case Type::AryPtr:   // do not distinguish arrays at all
1530     case Type::InstPtr:  tj = TypeInstPtr::BOTTOM;  break;
1531     case Type::KlassPtr: tj = TypeKlassPtr::OBJECT; break;
1532     case Type::AnyPtr:   tj = TypePtr::BOTTOM;      break;  // caller checks it
1533     default: ShouldNotReachHere();
1534     }
1535     break;
1536   case 2:                       // No collapsing at level 2; keep all splits
1537   case 3:                       // No collapsing at level 3; keep all splits
1538     break;
1539   default:
1540     Unimplemented();
1541   }
1542 
1543   offset = tj->offset();
1544   assert( offset != Type::OffsetTop, "Offset has fallen from constant" );
1545 
1546   assert( (offset != Type::OffsetBot && tj->base() != Type::AryPtr) ||
1547           (offset == Type::OffsetBot && tj->base() == Type::AryPtr) ||
1548           (offset == Type::OffsetBot && tj == TypeOopPtr::BOTTOM) ||
1549           (offset == Type::OffsetBot && tj == TypePtr::BOTTOM) ||
1550           (offset == oopDesc::mark_offset_in_bytes() && tj->base() == Type::AryPtr) ||
1551           (offset == oopDesc::klass_offset_in_bytes() && tj->base() == Type::AryPtr) ||
1552           (offset == arrayOopDesc::length_offset_in_bytes() && tj->base() == Type::AryPtr)  ,
1553           "For oops, klasses, raw offset must be constant; for arrays the offset is never known" );
1554   assert( tj->ptr() != TypePtr::TopPTR &&
1555           tj->ptr() != TypePtr::AnyNull &&
1556           tj->ptr() != TypePtr::Null, "No imprecise addresses" );
1557 //    assert( tj->ptr() != TypePtr::Constant ||
1558 //            tj->base() == Type::RawPtr ||
1559 //            tj->base() == Type::KlassPtr, "No constant oop addresses" );
1560 
1561   return tj;
1562 }
1563 
1564 void Compile::AliasType::Init(int i, const TypePtr* at) {
1565   _index = i;
1566   _adr_type = at;
1567   _field = NULL;
1568   _element = NULL;
1569   _is_rewritable = true; // default
1570   const TypeOopPtr *atoop = (at != NULL) ? at->isa_oopptr() : NULL;
1571   if (atoop != NULL && atoop->is_known_instance()) {
1572     const TypeOopPtr *gt = atoop->cast_to_instance_id(TypeOopPtr::InstanceBot);
1573     _general_index = Compile::current()->get_alias_index(gt);
1574   } else {
1575     _general_index = 0;
1576   }
1577 }
1578 
1579 //---------------------------------print_on------------------------------------
1580 #ifndef PRODUCT
1581 void Compile::AliasType::print_on(outputStream* st) {
1582   if (index() < 10)
1583         st->print("@ <%d> ", index());
1584   else  st->print("@ <%d>",  index());
1585   st->print(is_rewritable() ? "   " : " RO");
1586   int offset = adr_type()->offset();
1587   if (offset == Type::OffsetBot)
1588         st->print(" +any");
1589   else  st->print(" +%-3d", offset);
1590   st->print(" in ");
1591   adr_type()->dump_on(st);
1592   const TypeOopPtr* tjp = adr_type()->isa_oopptr();
1593   if (field() != NULL && tjp) {
1594     if (tjp->klass()  != field()->holder() ||
1595         tjp->offset() != field()->offset_in_bytes()) {
1596       st->print(" != ");
1597       field()->print();
1598       st->print(" ***");
1599     }
1600   }
1601 }
1602 
1603 void print_alias_types() {
1604   Compile* C = Compile::current();
1605   tty->print_cr("--- Alias types, AliasIdxBot .. %d", C->num_alias_types()-1);
1606   for (int idx = Compile::AliasIdxBot; idx < C->num_alias_types(); idx++) {
1607     C->alias_type(idx)->print_on(tty);
1608     tty->cr();
1609   }
1610 }
1611 #endif
1612 
1613 
1614 //----------------------------probe_alias_cache--------------------------------
1615 Compile::AliasCacheEntry* Compile::probe_alias_cache(const TypePtr* adr_type) {
1616   intptr_t key = (intptr_t) adr_type;
1617   key ^= key >> logAliasCacheSize;
1618   return &_alias_cache[key & right_n_bits(logAliasCacheSize)];
1619 }
1620 
1621 
1622 //-----------------------------grow_alias_types--------------------------------
1623 void Compile::grow_alias_types() {
1624   const int old_ats  = _max_alias_types; // how many before?
1625   const int new_ats  = old_ats;          // how many more?
1626   const int grow_ats = old_ats+new_ats;  // how many now?
1627   _max_alias_types = grow_ats;
1628   _alias_types =  REALLOC_ARENA_ARRAY(comp_arena(), AliasType*, _alias_types, old_ats, grow_ats);
1629   AliasType* ats =    NEW_ARENA_ARRAY(comp_arena(), AliasType, new_ats);
1630   Copy::zero_to_bytes(ats, sizeof(AliasType)*new_ats);
1631   for (int i = 0; i < new_ats; i++)  _alias_types[old_ats+i] = &ats[i];
1632 }
1633 
1634 
1635 //--------------------------------find_alias_type------------------------------
1636 Compile::AliasType* Compile::find_alias_type(const TypePtr* adr_type, bool no_create, ciField* original_field) {
1637   if (_AliasLevel == 0)
1638     return alias_type(AliasIdxBot);
1639 
1640   AliasCacheEntry* ace = probe_alias_cache(adr_type);
1641   if (ace->_adr_type == adr_type) {
1642     return alias_type(ace->_index);
1643   }
1644 
1645   // Handle special cases.
1646   if (adr_type == NULL)             return alias_type(AliasIdxTop);
1647   if (adr_type == TypePtr::BOTTOM)  return alias_type(AliasIdxBot);
1648 
1649   // Do it the slow way.
1650   const TypePtr* flat = flatten_alias_type(adr_type);
1651 
1652 #ifdef ASSERT
1653   assert(flat == flatten_alias_type(flat), "idempotent");
1654   assert(flat != TypePtr::BOTTOM,     "cannot alias-analyze an untyped ptr");
1655   if (flat->isa_oopptr() && !flat->isa_klassptr()) {
1656     const TypeOopPtr* foop = flat->is_oopptr();
1657     // Scalarizable allocations have exact klass always.
1658     bool exact = !foop->klass_is_exact() || foop->is_known_instance();
1659     const TypePtr* xoop = foop->cast_to_exactness(exact)->is_ptr();
1660     assert(foop == flatten_alias_type(xoop), "exactness must not affect alias type");
1661   }
1662   assert(flat == flatten_alias_type(flat), "exact bit doesn't matter");
1663 #endif
1664 
1665   int idx = AliasIdxTop;
1666   for (int i = 0; i < num_alias_types(); i++) {
1667     if (alias_type(i)->adr_type() == flat) {
1668       idx = i;
1669       break;
1670     }
1671   }
1672 
1673   if (idx == AliasIdxTop) {
1674     if (no_create)  return NULL;
1675     // Grow the array if necessary.
1676     if (_num_alias_types == _max_alias_types)  grow_alias_types();
1677     // Add a new alias type.
1678     idx = _num_alias_types++;
1679     _alias_types[idx]->Init(idx, flat);
1680     if (flat == TypeInstPtr::KLASS)  alias_type(idx)->set_rewritable(false);
1681     if (flat == TypeAryPtr::RANGE)   alias_type(idx)->set_rewritable(false);
1682     if (flat->isa_instptr()) {
1683       if (flat->offset() == java_lang_Class::klass_offset_in_bytes()
1684           && flat->is_instptr()->klass() == env()->Class_klass())
1685         alias_type(idx)->set_rewritable(false);
1686     }
1687     if (flat->isa_aryptr()) {
1688 #ifdef ASSERT
1689       const int header_size_min  = arrayOopDesc::base_offset_in_bytes(T_BYTE);
1690       // (T_BYTE has the weakest alignment and size restrictions...)
1691       assert(flat->offset() < header_size_min, "array body reference must be OffsetBot");
1692 #endif
1693       if (flat->offset() == TypePtr::OffsetBot) {
1694         alias_type(idx)->set_element(flat->is_aryptr()->elem());
1695       }
1696     }
1697     if (flat->isa_klassptr()) {
1698       if (flat->offset() == in_bytes(Klass::super_check_offset_offset()))
1699         alias_type(idx)->set_rewritable(false);
1700       if (flat->offset() == in_bytes(Klass::modifier_flags_offset()))
1701         alias_type(idx)->set_rewritable(false);
1702       if (flat->offset() == in_bytes(Klass::access_flags_offset()))
1703         alias_type(idx)->set_rewritable(false);
1704       if (flat->offset() == in_bytes(Klass::java_mirror_offset()))
1705         alias_type(idx)->set_rewritable(false);
1706     }
1707     // %%% (We would like to finalize JavaThread::threadObj_offset(),
1708     // but the base pointer type is not distinctive enough to identify
1709     // references into JavaThread.)
1710 
1711     // Check for final fields.
1712     const TypeInstPtr* tinst = flat->isa_instptr();
1713     if (tinst && tinst->offset() >= instanceOopDesc::base_offset_in_bytes()) {
1714       ciField* field;
1715       if (tinst->const_oop() != NULL &&
1716           tinst->klass() == ciEnv::current()->Class_klass() &&
1717           tinst->offset() >= (tinst->klass()->as_instance_klass()->size_helper() * wordSize)) {
1718         // static field
1719         ciInstanceKlass* k = tinst->const_oop()->as_instance()->java_lang_Class_klass()->as_instance_klass();
1720         field = k->get_field_by_offset(tinst->offset(), true);
1721       } else {
1722         ciInstanceKlass *k = tinst->klass()->as_instance_klass();
1723         field = k->get_field_by_offset(tinst->offset(), false);
1724       }
1725       assert(field == NULL ||
1726              original_field == NULL ||
1727              (field->holder() == original_field->holder() &&
1728               field->offset() == original_field->offset() &&
1729               field->is_static() == original_field->is_static()), "wrong field?");
1730       // Set field() and is_rewritable() attributes.
1731       if (field != NULL)  alias_type(idx)->set_field(field);
1732     }
1733   }
1734 
1735   // Fill the cache for next time.
1736   ace->_adr_type = adr_type;
1737   ace->_index    = idx;
1738   assert(alias_type(adr_type) == alias_type(idx),  "type must be installed");
1739 
1740   // Might as well try to fill the cache for the flattened version, too.
1741   AliasCacheEntry* face = probe_alias_cache(flat);
1742   if (face->_adr_type == NULL) {
1743     face->_adr_type = flat;
1744     face->_index    = idx;
1745     assert(alias_type(flat) == alias_type(idx), "flat type must work too");
1746   }
1747 
1748   return alias_type(idx);
1749 }
1750 
1751 
1752 Compile::AliasType* Compile::alias_type(ciField* field) {
1753   const TypeOopPtr* t;
1754   if (field->is_static())
1755     t = TypeInstPtr::make(field->holder()->java_mirror());
1756   else
1757     t = TypeOopPtr::make_from_klass_raw(field->holder());
1758   AliasType* atp = alias_type(t->add_offset(field->offset_in_bytes()), field);
1759   assert((field->is_final() || field->is_stable()) == !atp->is_rewritable(), "must get the rewritable bits correct");
1760   return atp;
1761 }
1762 
1763 
1764 //------------------------------have_alias_type--------------------------------
1765 bool Compile::have_alias_type(const TypePtr* adr_type) {
1766   AliasCacheEntry* ace = probe_alias_cache(adr_type);
1767   if (ace->_adr_type == adr_type) {
1768     return true;
1769   }
1770 
1771   // Handle special cases.
1772   if (adr_type == NULL)             return true;
1773   if (adr_type == TypePtr::BOTTOM)  return true;
1774 
1775   return find_alias_type(adr_type, true, NULL) != NULL;
1776 }
1777 
1778 //-----------------------------must_alias--------------------------------------
1779 // True if all values of the given address type are in the given alias category.
1780 bool Compile::must_alias(const TypePtr* adr_type, int alias_idx) {
1781   if (alias_idx == AliasIdxBot)         return true;  // the universal category
1782   if (adr_type == NULL)                 return true;  // NULL serves as TypePtr::TOP
1783   if (alias_idx == AliasIdxTop)         return false; // the empty category
1784   if (adr_type->base() == Type::AnyPtr) return false; // TypePtr::BOTTOM or its twins
1785 
1786   // the only remaining possible overlap is identity
1787   int adr_idx = get_alias_index(adr_type);
1788   assert(adr_idx != AliasIdxBot && adr_idx != AliasIdxTop, "");
1789   assert(adr_idx == alias_idx ||
1790          (alias_type(alias_idx)->adr_type() != TypeOopPtr::BOTTOM
1791           && adr_type                       != TypeOopPtr::BOTTOM),
1792          "should not be testing for overlap with an unsafe pointer");
1793   return adr_idx == alias_idx;
1794 }
1795 
1796 //------------------------------can_alias--------------------------------------
1797 // True if any values of the given address type are in the given alias category.
1798 bool Compile::can_alias(const TypePtr* adr_type, int alias_idx) {
1799   if (alias_idx == AliasIdxTop)         return false; // the empty category
1800   if (adr_type == NULL)                 return false; // NULL serves as TypePtr::TOP
1801   if (alias_idx == AliasIdxBot)         return true;  // the universal category
1802   if (adr_type->base() == Type::AnyPtr) return true;  // TypePtr::BOTTOM or its twins
1803 
1804   // the only remaining possible overlap is identity
1805   int adr_idx = get_alias_index(adr_type);
1806   assert(adr_idx != AliasIdxBot && adr_idx != AliasIdxTop, "");
1807   return adr_idx == alias_idx;
1808 }
1809 
1810 
1811 
1812 //---------------------------pop_warm_call-------------------------------------
1813 WarmCallInfo* Compile::pop_warm_call() {
1814   WarmCallInfo* wci = _warm_calls;
1815   if (wci != NULL)  _warm_calls = wci->remove_from(wci);
1816   return wci;
1817 }
1818 
1819 //----------------------------Inline_Warm--------------------------------------
1820 int Compile::Inline_Warm() {
1821   // If there is room, try to inline some more warm call sites.
1822   // %%% Do a graph index compaction pass when we think we're out of space?
1823   if (!InlineWarmCalls)  return 0;
1824 
1825   int calls_made_hot = 0;
1826   int room_to_grow   = NodeCountInliningCutoff - unique();
1827   int amount_to_grow = MIN2(room_to_grow, (int)NodeCountInliningStep);
1828   int amount_grown   = 0;
1829   WarmCallInfo* call;
1830   while (amount_to_grow > 0 && (call = pop_warm_call()) != NULL) {
1831     int est_size = (int)call->size();
1832     if (est_size > (room_to_grow - amount_grown)) {
1833       // This one won't fit anyway.  Get rid of it.
1834       call->make_cold();
1835       continue;
1836     }
1837     call->make_hot();
1838     calls_made_hot++;
1839     amount_grown   += est_size;
1840     amount_to_grow -= est_size;
1841   }
1842 
1843   if (calls_made_hot > 0)  set_major_progress();
1844   return calls_made_hot;
1845 }
1846 
1847 
1848 //----------------------------Finish_Warm--------------------------------------
1849 void Compile::Finish_Warm() {
1850   if (!InlineWarmCalls)  return;
1851   if (failing())  return;
1852   if (warm_calls() == NULL)  return;
1853 
1854   // Clean up loose ends, if we are out of space for inlining.
1855   WarmCallInfo* call;
1856   while ((call = pop_warm_call()) != NULL) {
1857     call->make_cold();
1858   }
1859 }
1860 
1861 //---------------------cleanup_loop_predicates-----------------------
1862 // Remove the opaque nodes that protect the predicates so that all unused
1863 // checks and uncommon_traps will be eliminated from the ideal graph
1864 void Compile::cleanup_loop_predicates(PhaseIterGVN &igvn) {
1865   if (predicate_count()==0) return;
1866   for (int i = predicate_count(); i > 0; i--) {
1867     Node * n = predicate_opaque1_node(i-1);
1868     assert(n->Opcode() == Op_Opaque1, "must be");
1869     igvn.replace_node(n, n->in(1));
1870   }
1871   assert(predicate_count()==0, "should be clean!");
1872 }
1873 
1874 // StringOpts and late inlining of string methods
1875 void Compile::inline_string_calls(bool parse_time) {
1876   {
1877     // remove useless nodes to make the usage analysis simpler
1878     ResourceMark rm;
1879     PhaseRemoveUseless pru(initial_gvn(), for_igvn());
1880   }
1881 
1882   {
1883     ResourceMark rm;
1884     print_method(PHASE_BEFORE_STRINGOPTS, 3);
1885     PhaseStringOpts pso(initial_gvn(), for_igvn());
1886     print_method(PHASE_AFTER_STRINGOPTS, 3);
1887   }
1888 
1889   // now inline anything that we skipped the first time around
1890   if (!parse_time) {
1891     _late_inlines_pos = _late_inlines.length();
1892   }
1893 
1894   while (_string_late_inlines.length() > 0) {
1895     CallGenerator* cg = _string_late_inlines.pop();
1896     cg->do_late_inline();
1897     if (failing())  return;
1898   }
1899   _string_late_inlines.trunc_to(0);
1900 }
1901 
1902 // Late inlining of boxing methods
1903 void Compile::inline_boxing_calls(PhaseIterGVN& igvn) {
1904   if (_boxing_late_inlines.length() > 0) {
1905     assert(has_boxed_value(), "inconsistent");
1906 
1907     PhaseGVN* gvn = initial_gvn();
1908     set_inlining_incrementally(true);
1909 
1910     assert( igvn._worklist.size() == 0, "should be done with igvn" );
1911     for_igvn()->clear();
1912     gvn->replace_with(&igvn);
1913 
1914     _late_inlines_pos = _late_inlines.length();
1915 
1916     while (_boxing_late_inlines.length() > 0) {
1917       CallGenerator* cg = _boxing_late_inlines.pop();
1918       cg->do_late_inline();
1919       if (failing())  return;
1920     }
1921     _boxing_late_inlines.trunc_to(0);
1922 
1923     {
1924       ResourceMark rm;
1925       PhaseRemoveUseless pru(gvn, for_igvn());
1926     }
1927 
1928     igvn = PhaseIterGVN(gvn);
1929     igvn.optimize();
1930 
1931     set_inlining_progress(false);
1932     set_inlining_incrementally(false);
1933   }
1934 }
1935 
1936 void Compile::inline_incrementally_one(PhaseIterGVN& igvn) {
1937   assert(IncrementalInline, "incremental inlining should be on");
1938   PhaseGVN* gvn = initial_gvn();
1939 
1940   set_inlining_progress(false);
1941   for_igvn()->clear();
1942   gvn->replace_with(&igvn);
1943 
1944   int i = 0;
1945 
1946   for (; i <_late_inlines.length() && !inlining_progress(); i++) {
1947     CallGenerator* cg = _late_inlines.at(i);
1948     _late_inlines_pos = i+1;
1949     cg->do_late_inline();
1950     if (failing())  return;
1951   }
1952   int j = 0;
1953   for (; i < _late_inlines.length(); i++, j++) {
1954     _late_inlines.at_put(j, _late_inlines.at(i));
1955   }
1956   _late_inlines.trunc_to(j);
1957 
1958   {
1959     ResourceMark rm;
1960     PhaseRemoveUseless pru(gvn, for_igvn());
1961   }
1962 
1963   igvn = PhaseIterGVN(gvn);
1964 }
1965 
1966 // Perform incremental inlining until bound on number of live nodes is reached
1967 void Compile::inline_incrementally(PhaseIterGVN& igvn) {
1968   PhaseGVN* gvn = initial_gvn();
1969 
1970   set_inlining_incrementally(true);
1971   set_inlining_progress(true);
1972   uint low_live_nodes = 0;
1973 
1974   while(inlining_progress() && _late_inlines.length() > 0) {
1975 
1976     if (live_nodes() > (uint)LiveNodeCountInliningCutoff) {
1977       if (low_live_nodes < (uint)LiveNodeCountInliningCutoff * 8 / 10) {
1978         // PhaseIdealLoop is expensive so we only try it once we are
1979         // out of live nodes and we only try it again if the previous
1980         // helped got the number of nodes down significantly
1981         PhaseIdealLoop ideal_loop( igvn, false, true );
1982         if (failing())  return;
1983         low_live_nodes = live_nodes();
1984         _major_progress = true;
1985       }
1986 
1987       if (live_nodes() > (uint)LiveNodeCountInliningCutoff) {
1988         break;
1989       }
1990     }
1991 
1992     inline_incrementally_one(igvn);
1993 
1994     if (failing())  return;
1995 
1996     igvn.optimize();
1997 
1998     if (failing())  return;
1999   }
2000 
2001   assert( igvn._worklist.size() == 0, "should be done with igvn" );
2002 
2003   if (_string_late_inlines.length() > 0) {
2004     assert(has_stringbuilder(), "inconsistent");
2005     for_igvn()->clear();
2006     initial_gvn()->replace_with(&igvn);
2007 
2008     inline_string_calls(false);
2009 
2010     if (failing())  return;
2011 
2012     {
2013       ResourceMark rm;
2014       PhaseRemoveUseless pru(initial_gvn(), for_igvn());
2015     }
2016 
2017     igvn = PhaseIterGVN(gvn);
2018 
2019     igvn.optimize();
2020   }
2021 
2022   set_inlining_incrementally(false);
2023 }
2024 
2025 
2026 //------------------------------Optimize---------------------------------------
2027 // Given a graph, optimize it.
2028 void Compile::Optimize() {
2029   TracePhase t1("optimizer", &_t_optimizer, true);
2030 
2031 #ifndef PRODUCT
2032   if (env()->break_at_compile()) {
2033     BREAKPOINT;
2034   }
2035 
2036 #endif
2037 
2038   ResourceMark rm;
2039   int          loop_opts_cnt;
2040 
2041   print_inlining_reinit();
2042 
2043   NOT_PRODUCT( verify_graph_edges(); )
2044 
2045   print_method(PHASE_AFTER_PARSING);
2046 
2047  {
2048   // Iterative Global Value Numbering, including ideal transforms
2049   // Initialize IterGVN with types and values from parse-time GVN
2050   PhaseIterGVN igvn(initial_gvn());
2051 #ifdef ASSERT
2052   _modified_nodes = new (comp_arena()) Unique_Node_List(comp_arena());
2053 #endif
2054   {
2055     NOT_PRODUCT( TracePhase t2("iterGVN", &_t_iterGVN, TimeCompiler); )
2056     igvn.optimize();
2057   }
2058 
2059   print_method(PHASE_ITER_GVN1, 2);
2060 
2061   if (failing())  return;
2062 
2063   {
2064     NOT_PRODUCT( TracePhase t2("incrementalInline", &_t_incrInline, TimeCompiler); )
2065     inline_incrementally(igvn);
2066   }
2067 
2068   print_method(PHASE_INCREMENTAL_INLINE, 2);
2069 
2070   if (failing())  return;
2071 
2072   if (eliminate_boxing()) {
2073     NOT_PRODUCT( TracePhase t2("incrementalInline", &_t_incrInline, TimeCompiler); )
2074     // Inline valueOf() methods now.
2075     inline_boxing_calls(igvn);
2076 
2077     if (AlwaysIncrementalInline) {
2078       inline_incrementally(igvn);
2079     }
2080 
2081     print_method(PHASE_INCREMENTAL_BOXING_INLINE, 2);
2082 
2083     if (failing())  return;
2084   }
2085 
2086   // Remove the speculative part of types and clean up the graph from
2087   // the extra CastPP nodes whose only purpose is to carry them. Do
2088   // that early so that optimizations are not disrupted by the extra
2089   // CastPP nodes.
2090   remove_speculative_types(igvn);
2091 
2092   // No more new expensive nodes will be added to the list from here
2093   // so keep only the actual candidates for optimizations.
2094   cleanup_expensive_nodes(igvn);
2095 
2096   // Perform escape analysis
2097   if (_do_escape_analysis && ConnectionGraph::has_candidates(this)) {
2098     if (has_loops()) {
2099       // Cleanup graph (remove dead nodes).
2100       TracePhase t2("idealLoop", &_t_idealLoop, true);
2101       PhaseIdealLoop ideal_loop( igvn, false, true );
2102       if (major_progress()) print_method(PHASE_PHASEIDEAL_BEFORE_EA, 2);
2103       if (failing())  return;
2104     }
2105     ConnectionGraph::do_analysis(this, &igvn);
2106 
2107     if (failing())  return;
2108 
2109     // Optimize out fields loads from scalar replaceable allocations.
2110     igvn.optimize();
2111     print_method(PHASE_ITER_GVN_AFTER_EA, 2);
2112 
2113     if (failing())  return;
2114 
2115     if (congraph() != NULL && macro_count() > 0) {
2116       NOT_PRODUCT( TracePhase t2("macroEliminate", &_t_macroEliminate, TimeCompiler); )
2117       PhaseMacroExpand mexp(igvn);
2118       mexp.eliminate_macro_nodes();
2119       igvn.set_delay_transform(false);
2120 
2121       igvn.optimize();
2122       print_method(PHASE_ITER_GVN_AFTER_ELIMINATION, 2);
2123 
2124       if (failing())  return;
2125     }
2126   }
2127 
2128   // Loop transforms on the ideal graph.  Range Check Elimination,
2129   // peeling, unrolling, etc.
2130 
2131   // Set loop opts counter
2132   loop_opts_cnt = num_loop_opts();
2133   if((loop_opts_cnt > 0) && (has_loops() || has_split_ifs())) {
2134     {
2135       TracePhase t2("idealLoop", &_t_idealLoop, true);
2136       PhaseIdealLoop ideal_loop( igvn, true );
2137       loop_opts_cnt--;
2138       if (major_progress()) print_method(PHASE_PHASEIDEALLOOP1, 2);
2139       if (failing())  return;
2140     }
2141     // Loop opts pass if partial peeling occurred in previous pass
2142     if(PartialPeelLoop && major_progress() && (loop_opts_cnt > 0)) {
2143       TracePhase t3("idealLoop", &_t_idealLoop, true);
2144       PhaseIdealLoop ideal_loop( igvn, false );
2145       loop_opts_cnt--;
2146       if (major_progress()) print_method(PHASE_PHASEIDEALLOOP2, 2);
2147       if (failing())  return;
2148     }
2149     // Loop opts pass for loop-unrolling before CCP
2150     if(major_progress() && (loop_opts_cnt > 0)) {
2151       TracePhase t4("idealLoop", &_t_idealLoop, true);
2152       PhaseIdealLoop ideal_loop( igvn, false );
2153       loop_opts_cnt--;
2154       if (major_progress()) print_method(PHASE_PHASEIDEALLOOP3, 2);
2155     }
2156     if (!failing()) {
2157       // Verify that last round of loop opts produced a valid graph
2158       NOT_PRODUCT( TracePhase t2("idealLoopVerify", &_t_idealLoopVerify, TimeCompiler); )
2159       PhaseIdealLoop::verify(igvn);
2160     }
2161   }
2162   if (failing())  return;
2163 
2164   // Conditional Constant Propagation;
2165   PhaseCCP ccp( &igvn );
2166   assert( true, "Break here to ccp.dump_nodes_and_types(_root,999,1)");
2167   {
2168     TracePhase t2("ccp", &_t_ccp, true);
2169     ccp.do_transform();
2170   }
2171   print_method(PHASE_CPP1, 2);
2172 
2173   assert( true, "Break here to ccp.dump_old2new_map()");
2174 
2175   // Iterative Global Value Numbering, including ideal transforms
2176   {
2177     NOT_PRODUCT( TracePhase t2("iterGVN2", &_t_iterGVN2, TimeCompiler); )
2178     igvn = ccp;
2179     igvn.optimize();
2180   }
2181 
2182   print_method(PHASE_ITER_GVN2, 2);
2183 
2184   if (failing())  return;
2185 
2186   // Loop transforms on the ideal graph.  Range Check Elimination,
2187   // peeling, unrolling, etc.
2188   if(loop_opts_cnt > 0) {
2189     debug_only( int cnt = 0; );
2190     while(major_progress() && (loop_opts_cnt > 0)) {
2191       TracePhase t2("idealLoop", &_t_idealLoop, true);
2192       assert( cnt++ < 40, "infinite cycle in loop optimization" );
2193       PhaseIdealLoop ideal_loop( igvn, true);
2194       loop_opts_cnt--;
2195       if (major_progress()) print_method(PHASE_PHASEIDEALLOOP_ITERATIONS, 2);
2196       if (failing())  return;
2197     }
2198   }
2199 
2200   {
2201     // Verify that all previous optimizations produced a valid graph
2202     // at least to this point, even if no loop optimizations were done.
2203     NOT_PRODUCT( TracePhase t2("idealLoopVerify", &_t_idealLoopVerify, TimeCompiler); )
2204     PhaseIdealLoop::verify(igvn);
2205   }
2206 
2207   {
2208     NOT_PRODUCT( TracePhase t2("macroExpand", &_t_macroExpand, TimeCompiler); )
2209     PhaseMacroExpand  mex(igvn);
2210     if (mex.expand_macro_nodes()) {
2211       assert(failing(), "must bail out w/ explicit message");
2212       return;
2213     }
2214   }
2215 
2216   DEBUG_ONLY( _modified_nodes = NULL; )
2217  } // (End scope of igvn; run destructor if necessary for asserts.)
2218 
2219   process_print_inlining();
2220   // A method with only infinite loops has no edges entering loops from root
2221   {
2222     NOT_PRODUCT( TracePhase t2("graphReshape", &_t_graphReshaping, TimeCompiler); )
2223     if (final_graph_reshaping()) {
2224       assert(failing(), "must bail out w/ explicit message");
2225       return;
2226     }
2227   }
2228 
2229   print_method(PHASE_OPTIMIZE_FINISHED, 2);
2230 }
2231 
2232 
2233 //------------------------------Code_Gen---------------------------------------
2234 // Given a graph, generate code for it
2235 void Compile::Code_Gen() {
2236   if (failing()) {
2237     return;
2238   }
2239 
2240   // Perform instruction selection.  You might think we could reclaim Matcher
2241   // memory PDQ, but actually the Matcher is used in generating spill code.
2242   // Internals of the Matcher (including some VectorSets) must remain live
2243   // for awhile - thus I cannot reclaim Matcher memory lest a VectorSet usage
2244   // set a bit in reclaimed memory.
2245 
2246   // In debug mode can dump m._nodes.dump() for mapping of ideal to machine
2247   // nodes.  Mapping is only valid at the root of each matched subtree.
2248   NOT_PRODUCT( verify_graph_edges(); )
2249 
2250   Matcher matcher;
2251   _matcher = &matcher;
2252   {
2253     TracePhase t2("matcher", &_t_matcher, true);
2254     matcher.match();
2255   }
2256   // In debug mode can dump m._nodes.dump() for mapping of ideal to machine
2257   // nodes.  Mapping is only valid at the root of each matched subtree.
2258   NOT_PRODUCT( verify_graph_edges(); )
2259 
2260   // If you have too many nodes, or if matching has failed, bail out
2261   check_node_count(0, "out of nodes matching instructions");
2262   if (failing()) {
2263     return;
2264   }
2265 
2266   // Build a proper-looking CFG
2267   PhaseCFG cfg(node_arena(), root(), matcher);
2268   _cfg = &cfg;
2269   {
2270     NOT_PRODUCT( TracePhase t2("scheduler", &_t_scheduler, TimeCompiler); )
2271     bool success = cfg.do_global_code_motion();
2272     if (!success) {
2273       return;
2274     }
2275 
2276     print_method(PHASE_GLOBAL_CODE_MOTION, 2);
2277     NOT_PRODUCT( verify_graph_edges(); )
2278     debug_only( cfg.verify(); )
2279   }
2280 
2281   PhaseChaitin regalloc(unique(), cfg, matcher);
2282   _regalloc = &regalloc;
2283   {
2284     TracePhase t2("regalloc", &_t_registerAllocation, true);
2285     // Perform register allocation.  After Chaitin, use-def chains are
2286     // no longer accurate (at spill code) and so must be ignored.
2287     // Node->LRG->reg mappings are still accurate.
2288     _regalloc->Register_Allocate();
2289 
2290     // Bail out if the allocator builds too many nodes
2291     if (failing()) {
2292       return;
2293     }
2294   }
2295 
2296   // Prior to register allocation we kept empty basic blocks in case the
2297   // the allocator needed a place to spill.  After register allocation we
2298   // are not adding any new instructions.  If any basic block is empty, we
2299   // can now safely remove it.
2300   {
2301     NOT_PRODUCT( TracePhase t2("blockOrdering", &_t_blockOrdering, TimeCompiler); )
2302     cfg.remove_empty_blocks();
2303     if (do_freq_based_layout()) {
2304       PhaseBlockLayout layout(cfg);
2305     } else {
2306       cfg.set_loop_alignment();
2307     }
2308     cfg.fixup_flow();
2309   }
2310 
2311   // Apply peephole optimizations
2312   if( OptoPeephole ) {
2313     NOT_PRODUCT( TracePhase t2("peephole", &_t_peephole, TimeCompiler); )
2314     PhasePeephole peep( _regalloc, cfg);
2315     peep.do_transform();
2316   }
2317 
2318   // Do late expand if CPU requires this.
2319   if (Matcher::require_postalloc_expand) {
2320     NOT_PRODUCT(TracePhase t2c("postalloc_expand", &_t_postalloc_expand, true));
2321     cfg.postalloc_expand(_regalloc);
2322   }
2323 
2324   // Convert Nodes to instruction bits in a buffer
2325   {
2326     // %%%% workspace merge brought two timers together for one job
2327     TracePhase t2a("output", &_t_output, true);
2328     NOT_PRODUCT( TraceTime t2b(NULL, &_t_codeGeneration, TimeCompiler, false); )
2329     Output();
2330   }
2331 
2332   print_method(PHASE_FINAL_CODE);
2333 
2334   // He's dead, Jim.
2335   _cfg     = (PhaseCFG*)0xdeadbeef;
2336   _regalloc = (PhaseChaitin*)0xdeadbeef;
2337 }
2338 
2339 
2340 //------------------------------dump_asm---------------------------------------
2341 // Dump formatted assembly
2342 #ifndef PRODUCT
2343 void Compile::dump_asm(int *pcs, uint pc_limit) {
2344   bool cut_short = false;
2345   tty->print_cr("#");
2346   tty->print("#  ");  _tf->dump();  tty->cr();
2347   tty->print_cr("#");
2348 
2349   // For all blocks
2350   int pc = 0x0;                 // Program counter
2351   char starts_bundle = ' ';
2352   _regalloc->dump_frame();
2353 
2354   Node *n = NULL;
2355   for (uint i = 0; i < _cfg->number_of_blocks(); i++) {
2356     if (VMThread::should_terminate()) {
2357       cut_short = true;
2358       break;
2359     }
2360     Block* block = _cfg->get_block(i);
2361     if (block->is_connector() && !Verbose) {
2362       continue;
2363     }
2364     n = block->head();
2365     if (pcs && n->_idx < pc_limit) {
2366       tty->print("%3.3x   ", pcs[n->_idx]);
2367     } else {
2368       tty->print("      ");
2369     }
2370     block->dump_head(_cfg);
2371     if (block->is_connector()) {
2372       tty->print_cr("        # Empty connector block");
2373     } else if (block->num_preds() == 2 && block->pred(1)->is_CatchProj() && block->pred(1)->as_CatchProj()->_con == CatchProjNode::fall_through_index) {
2374       tty->print_cr("        # Block is sole successor of call");
2375     }
2376 
2377     // For all instructions
2378     Node *delay = NULL;
2379     for (uint j = 0; j < block->number_of_nodes(); j++) {
2380       if (VMThread::should_terminate()) {
2381         cut_short = true;
2382         break;
2383       }
2384       n = block->get_node(j);
2385       if (valid_bundle_info(n)) {
2386         Bundle* bundle = node_bundling(n);
2387         if (bundle->used_in_unconditional_delay()) {
2388           delay = n;
2389           continue;
2390         }
2391         if (bundle->starts_bundle()) {
2392           starts_bundle = '+';
2393         }
2394       }
2395 
2396       if (WizardMode) {
2397         n->dump();
2398       }
2399 
2400       if( !n->is_Region() &&    // Dont print in the Assembly
2401           !n->is_Phi() &&       // a few noisely useless nodes
2402           !n->is_Proj() &&
2403           !n->is_MachTemp() &&
2404           !n->is_SafePointScalarObject() &&
2405           !n->is_Catch() &&     // Would be nice to print exception table targets
2406           !n->is_MergeMem() &&  // Not very interesting
2407           !n->is_top() &&       // Debug info table constants
2408           !(n->is_Con() && !n->is_Mach())// Debug info table constants
2409           ) {
2410         if (pcs && n->_idx < pc_limit)
2411           tty->print("%3.3x", pcs[n->_idx]);
2412         else
2413           tty->print("   ");
2414         tty->print(" %c ", starts_bundle);
2415         starts_bundle = ' ';
2416         tty->print("\t");
2417         n->format(_regalloc, tty);
2418         tty->cr();
2419       }
2420 
2421       // If we have an instruction with a delay slot, and have seen a delay,
2422       // then back up and print it
2423       if (valid_bundle_info(n) && node_bundling(n)->use_unconditional_delay()) {
2424         assert(delay != NULL, "no unconditional delay instruction");
2425         if (WizardMode) delay->dump();
2426 
2427         if (node_bundling(delay)->starts_bundle())
2428           starts_bundle = '+';
2429         if (pcs && n->_idx < pc_limit)
2430           tty->print("%3.3x", pcs[n->_idx]);
2431         else
2432           tty->print("   ");
2433         tty->print(" %c ", starts_bundle);
2434         starts_bundle = ' ';
2435         tty->print("\t");
2436         delay->format(_regalloc, tty);
2437         tty->cr();
2438         delay = NULL;
2439       }
2440 
2441       // Dump the exception table as well
2442       if( n->is_Catch() && (Verbose || WizardMode) ) {
2443         // Print the exception table for this offset
2444         _handler_table.print_subtable_for(pc);
2445       }
2446     }
2447 
2448     if (pcs && n->_idx < pc_limit)
2449       tty->print_cr("%3.3x", pcs[n->_idx]);
2450     else
2451       tty->cr();
2452 
2453     assert(cut_short || delay == NULL, "no unconditional delay branch");
2454 
2455   } // End of per-block dump
2456   tty->cr();
2457 
2458   if (cut_short)  tty->print_cr("*** disassembly is cut short ***");
2459 }
2460 #endif
2461 
2462 //------------------------------Final_Reshape_Counts---------------------------
2463 // This class defines counters to help identify when a method
2464 // may/must be executed using hardware with only 24-bit precision.
2465 struct Final_Reshape_Counts : public StackObj {
2466   int  _call_count;             // count non-inlined 'common' calls
2467   int  _float_count;            // count float ops requiring 24-bit precision
2468   int  _double_count;           // count double ops requiring more precision
2469   int  _java_call_count;        // count non-inlined 'java' calls
2470   int  _inner_loop_count;       // count loops which need alignment
2471   VectorSet _visited;           // Visitation flags
2472   Node_List _tests;             // Set of IfNodes & PCTableNodes
2473 
2474   Final_Reshape_Counts() :
2475     _call_count(0), _float_count(0), _double_count(0),
2476     _java_call_count(0), _inner_loop_count(0),
2477     _visited( Thread::current()->resource_area() ) { }
2478 
2479   void inc_call_count  () { _call_count  ++; }
2480   void inc_float_count () { _float_count ++; }
2481   void inc_double_count() { _double_count++; }
2482   void inc_java_call_count() { _java_call_count++; }
2483   void inc_inner_loop_count() { _inner_loop_count++; }
2484 
2485   int  get_call_count  () const { return _call_count  ; }
2486   int  get_float_count () const { return _float_count ; }
2487   int  get_double_count() const { return _double_count; }
2488   int  get_java_call_count() const { return _java_call_count; }
2489   int  get_inner_loop_count() const { return _inner_loop_count; }
2490 };
2491 
2492 #ifdef ASSERT
2493 static bool oop_offset_is_sane(const TypeInstPtr* tp) {
2494   ciInstanceKlass *k = tp->klass()->as_instance_klass();
2495   // Make sure the offset goes inside the instance layout.
2496   return k->contains_field_offset(tp->offset());
2497   // Note that OffsetBot and OffsetTop are very negative.
2498 }
2499 #endif
2500 
2501 // Eliminate trivially redundant StoreCMs and accumulate their
2502 // precedence edges.
2503 void Compile::eliminate_redundant_card_marks(Node* n) {
2504   assert(n->Opcode() == Op_StoreCM, "expected StoreCM");
2505   if (n->in(MemNode::Address)->outcnt() > 1) {
2506     // There are multiple users of the same address so it might be
2507     // possible to eliminate some of the StoreCMs
2508     Node* mem = n->in(MemNode::Memory);
2509     Node* adr = n->in(MemNode::Address);
2510     Node* val = n->in(MemNode::ValueIn);
2511     Node* prev = n;
2512     bool done = false;
2513     // Walk the chain of StoreCMs eliminating ones that match.  As
2514     // long as it's a chain of single users then the optimization is
2515     // safe.  Eliminating partially redundant StoreCMs would require
2516     // cloning copies down the other paths.
2517     while (mem->Opcode() == Op_StoreCM && mem->outcnt() == 1 && !done) {
2518       if (adr == mem->in(MemNode::Address) &&
2519           val == mem->in(MemNode::ValueIn)) {
2520         // redundant StoreCM
2521         if (mem->req() > MemNode::OopStore) {
2522           // Hasn't been processed by this code yet.
2523           n->add_prec(mem->in(MemNode::OopStore));
2524         } else {
2525           // Already converted to precedence edge
2526           for (uint i = mem->req(); i < mem->len(); i++) {
2527             // Accumulate any precedence edges
2528             if (mem->in(i) != NULL) {
2529               n->add_prec(mem->in(i));
2530             }
2531           }
2532           // Everything above this point has been processed.
2533           done = true;
2534         }
2535         // Eliminate the previous StoreCM
2536         prev->set_req(MemNode::Memory, mem->in(MemNode::Memory));
2537         assert(mem->outcnt() == 0, "should be dead");
2538         mem->disconnect_inputs(NULL, this);
2539       } else {
2540         prev = mem;
2541       }
2542       mem = prev->in(MemNode::Memory);
2543     }
2544   }
2545 }
2546 
2547 //------------------------------final_graph_reshaping_impl----------------------
2548 // Implement items 1-5 from final_graph_reshaping below.
2549 void Compile::final_graph_reshaping_impl( Node *n, Final_Reshape_Counts &frc) {
2550 
2551   if ( n->outcnt() == 0 ) return; // dead node
2552   uint nop = n->Opcode();
2553 
2554   // Check for 2-input instruction with "last use" on right input.
2555   // Swap to left input.  Implements item (2).
2556   if( n->req() == 3 &&          // two-input instruction
2557       n->in(1)->outcnt() > 1 && // left use is NOT a last use
2558       (!n->in(1)->is_Phi() || n->in(1)->in(2) != n) && // it is not data loop
2559       n->in(2)->outcnt() == 1 &&// right use IS a last use
2560       !n->in(2)->is_Con() ) {   // right use is not a constant
2561     // Check for commutative opcode
2562     switch( nop ) {
2563     case Op_AddI:  case Op_AddF:  case Op_AddD:  case Op_AddL:
2564     case Op_MaxI:  case Op_MinI:
2565     case Op_MulI:  case Op_MulF:  case Op_MulD:  case Op_MulL:
2566     case Op_AndL:  case Op_XorL:  case Op_OrL:
2567     case Op_AndI:  case Op_XorI:  case Op_OrI: {
2568       // Move "last use" input to left by swapping inputs
2569       n->swap_edges(1, 2);
2570       break;
2571     }
2572     default:
2573       break;
2574     }
2575   }
2576 
2577 #ifdef ASSERT
2578   if( n->is_Mem() ) {
2579     int alias_idx = get_alias_index(n->as_Mem()->adr_type());
2580     assert( n->in(0) != NULL || alias_idx != Compile::AliasIdxRaw ||
2581             // oop will be recorded in oop map if load crosses safepoint
2582             n->is_Load() && (n->as_Load()->bottom_type()->isa_oopptr() ||
2583                              LoadNode::is_immutable_value(n->in(MemNode::Address))),
2584             "raw memory operations should have control edge");
2585   }
2586 #endif
2587   // Count FPU ops and common calls, implements item (3)
2588   switch( nop ) {
2589   // Count all float operations that may use FPU
2590   case Op_AddF:
2591   case Op_SubF:
2592   case Op_MulF:
2593   case Op_DivF:
2594   case Op_NegF:
2595   case Op_ModF:
2596   case Op_ConvI2F:
2597   case Op_ConF:
2598   case Op_CmpF:
2599   case Op_CmpF3:
2600   // case Op_ConvL2F: // longs are split into 32-bit halves
2601     frc.inc_float_count();
2602     break;
2603 
2604   case Op_ConvF2D:
2605   case Op_ConvD2F:
2606     frc.inc_float_count();
2607     frc.inc_double_count();
2608     break;
2609 
2610   // Count all double operations that may use FPU
2611   case Op_AddD:
2612   case Op_SubD:
2613   case Op_MulD:
2614   case Op_DivD:
2615   case Op_NegD:
2616   case Op_ModD:
2617   case Op_ConvI2D:
2618   case Op_ConvD2I:
2619   // case Op_ConvL2D: // handled by leaf call
2620   // case Op_ConvD2L: // handled by leaf call
2621   case Op_ConD:
2622   case Op_CmpD:
2623   case Op_CmpD3:
2624     frc.inc_double_count();
2625     break;
2626   case Op_Opaque1:              // Remove Opaque Nodes before matching
2627   case Op_Opaque2:              // Remove Opaque Nodes before matching
2628   case Op_Opaque3:
2629     n->subsume_by(n->in(1), this);
2630     break;
2631   case Op_CallStaticJava:
2632   case Op_CallJava:
2633   case Op_CallDynamicJava:
2634     frc.inc_java_call_count(); // Count java call site;
2635   case Op_CallRuntime:
2636   case Op_CallLeaf:
2637   case Op_CallLeafNoFP: {
2638     assert( n->is_Call(), "" );
2639     CallNode *call = n->as_Call();
2640     // Count call sites where the FP mode bit would have to be flipped.
2641     // Do not count uncommon runtime calls:
2642     // uncommon_trap, _complete_monitor_locking, _complete_monitor_unlocking,
2643     // _new_Java, _new_typeArray, _new_objArray, _rethrow_Java, ...
2644     if( !call->is_CallStaticJava() || !call->as_CallStaticJava()->_name ) {
2645       frc.inc_call_count();   // Count the call site
2646     } else {                  // See if uncommon argument is shared
2647       Node *n = call->in(TypeFunc::Parms);
2648       int nop = n->Opcode();
2649       // Clone shared simple arguments to uncommon calls, item (1).
2650       if( n->outcnt() > 1 &&
2651           !n->is_Proj() &&
2652           nop != Op_CreateEx &&
2653           nop != Op_CheckCastPP &&
2654           nop != Op_DecodeN &&
2655           nop != Op_DecodeNKlass &&
2656           !n->is_Mem() ) {
2657         Node *x = n->clone();
2658         call->set_req( TypeFunc::Parms, x );
2659       }
2660     }
2661     break;
2662   }
2663 
2664   case Op_StoreD:
2665   case Op_LoadD:
2666   case Op_LoadD_unaligned:
2667     frc.inc_double_count();
2668     goto handle_mem;
2669   case Op_StoreF:
2670   case Op_LoadF:
2671     frc.inc_float_count();
2672     goto handle_mem;
2673 
2674   case Op_StoreCM:
2675     {
2676       // Convert OopStore dependence into precedence edge
2677       Node* prec = n->in(MemNode::OopStore);
2678       n->del_req(MemNode::OopStore);
2679       n->add_prec(prec);
2680       eliminate_redundant_card_marks(n);
2681     }
2682 
2683     // fall through
2684 
2685   case Op_StoreB:
2686   case Op_StoreC:
2687   case Op_StorePConditional:
2688   case Op_StoreI:
2689   case Op_StoreL:
2690   case Op_StoreIConditional:
2691   case Op_StoreLConditional:
2692   case Op_CompareAndSwapI:
2693   case Op_CompareAndSwapL:
2694   case Op_CompareAndSwapP:
2695   case Op_CompareAndSwapN:
2696   case Op_GetAndAddI:
2697   case Op_GetAndAddL:
2698   case Op_GetAndSetI:
2699   case Op_GetAndSetL:
2700   case Op_GetAndSetP:
2701   case Op_GetAndSetN:
2702   case Op_StoreP:
2703   case Op_StoreN:
2704   case Op_StoreNKlass:
2705   case Op_LoadB:
2706   case Op_LoadUB:
2707   case Op_LoadUS:
2708   case Op_LoadI:
2709   case Op_LoadKlass:
2710   case Op_LoadNKlass:
2711   case Op_LoadL:
2712   case Op_LoadL_unaligned:
2713   case Op_LoadPLocked:
2714   case Op_LoadP:
2715   case Op_LoadN:
2716   case Op_LoadRange:
2717   case Op_LoadS: {
2718   handle_mem:
2719 #ifdef ASSERT
2720     if( VerifyOptoOopOffsets ) {
2721       assert( n->is_Mem(), "" );
2722       MemNode *mem  = (MemNode*)n;
2723       // Check to see if address types have grounded out somehow.
2724       const TypeInstPtr *tp = mem->in(MemNode::Address)->bottom_type()->isa_instptr();
2725       assert( !tp || oop_offset_is_sane(tp), "" );
2726     }
2727 #endif
2728     break;
2729   }
2730 
2731   case Op_AddP: {               // Assert sane base pointers
2732     Node *addp = n->in(AddPNode::Address);
2733     assert( !addp->is_AddP() ||
2734             addp->in(AddPNode::Base)->is_top() || // Top OK for allocation
2735             addp->in(AddPNode::Base) == n->in(AddPNode::Base),
2736             "Base pointers must match" );
2737 #ifdef _LP64
2738     if ((UseCompressedOops || UseCompressedClassPointers) &&
2739         addp->Opcode() == Op_ConP &&
2740         addp == n->in(AddPNode::Base) &&
2741         n->in(AddPNode::Offset)->is_Con()) {
2742       // Use addressing with narrow klass to load with offset on x86.
2743       // On sparc loading 32-bits constant and decoding it have less
2744       // instructions (4) then load 64-bits constant (7).
2745       // Do this transformation here since IGVN will convert ConN back to ConP.
2746       const Type* t = addp->bottom_type();
2747       if (t->isa_oopptr() || t->isa_klassptr()) {
2748         Node* nn = NULL;
2749 
2750         int op = t->isa_oopptr() ? Op_ConN : Op_ConNKlass;
2751 
2752         // Look for existing ConN node of the same exact type.
2753         Node* r  = root();
2754         uint cnt = r->outcnt();
2755         for (uint i = 0; i < cnt; i++) {
2756           Node* m = r->raw_out(i);
2757           if (m!= NULL && m->Opcode() == op &&
2758               m->bottom_type()->make_ptr() == t) {
2759             nn = m;
2760             break;
2761           }
2762         }
2763         if (nn != NULL) {
2764           // Decode a narrow oop to match address
2765           // [R12 + narrow_oop_reg<<3 + offset]
2766           if (t->isa_oopptr()) {
2767             nn = new DecodeNNode(nn, t);
2768           } else {
2769             nn = new DecodeNKlassNode(nn, t);
2770           }
2771           n->set_req(AddPNode::Base, nn);
2772           n->set_req(AddPNode::Address, nn);
2773           if (addp->outcnt() == 0) {
2774             addp->disconnect_inputs(NULL, this);
2775           }
2776         }
2777       }
2778     }
2779 #endif
2780     break;
2781   }
2782 
2783 #ifdef _LP64
2784   case Op_CastPP:
2785     if (n->in(1)->is_DecodeN() && Matcher::gen_narrow_oop_implicit_null_checks()) {
2786       Node* in1 = n->in(1);
2787       const Type* t = n->bottom_type();
2788       Node* new_in1 = in1->clone();
2789       new_in1->as_DecodeN()->set_type(t);
2790 
2791       if (!Matcher::narrow_oop_use_complex_address()) {
2792         //
2793         // x86, ARM and friends can handle 2 adds in addressing mode
2794         // and Matcher can fold a DecodeN node into address by using
2795         // a narrow oop directly and do implicit NULL check in address:
2796         //
2797         // [R12 + narrow_oop_reg<<3 + offset]
2798         // NullCheck narrow_oop_reg
2799         //
2800         // On other platforms (Sparc) we have to keep new DecodeN node and
2801         // use it to do implicit NULL check in address:
2802         //
2803         // decode_not_null narrow_oop_reg, base_reg
2804         // [base_reg + offset]
2805         // NullCheck base_reg
2806         //
2807         // Pin the new DecodeN node to non-null path on these platform (Sparc)
2808         // to keep the information to which NULL check the new DecodeN node
2809         // corresponds to use it as value in implicit_null_check().
2810         //
2811         new_in1->set_req(0, n->in(0));
2812       }
2813 
2814       n->subsume_by(new_in1, this);
2815       if (in1->outcnt() == 0) {
2816         in1->disconnect_inputs(NULL, this);
2817       }
2818     }
2819     break;
2820 
2821   case Op_CmpP:
2822     // Do this transformation here to preserve CmpPNode::sub() and
2823     // other TypePtr related Ideal optimizations (for example, ptr nullness).
2824     if (n->in(1)->is_DecodeNarrowPtr() || n->in(2)->is_DecodeNarrowPtr()) {
2825       Node* in1 = n->in(1);
2826       Node* in2 = n->in(2);
2827       if (!in1->is_DecodeNarrowPtr()) {
2828         in2 = in1;
2829         in1 = n->in(2);
2830       }
2831       assert(in1->is_DecodeNarrowPtr(), "sanity");
2832 
2833       Node* new_in2 = NULL;
2834       if (in2->is_DecodeNarrowPtr()) {
2835         assert(in2->Opcode() == in1->Opcode(), "must be same node type");
2836         new_in2 = in2->in(1);
2837       } else if (in2->Opcode() == Op_ConP) {
2838         const Type* t = in2->bottom_type();
2839         if (t == TypePtr::NULL_PTR) {
2840           assert(in1->is_DecodeN(), "compare klass to null?");
2841           // Don't convert CmpP null check into CmpN if compressed
2842           // oops implicit null check is not generated.
2843           // This will allow to generate normal oop implicit null check.
2844           if (Matcher::gen_narrow_oop_implicit_null_checks())
2845             new_in2 = ConNode::make(this, TypeNarrowOop::NULL_PTR);
2846           //
2847           // This transformation together with CastPP transformation above
2848           // will generated code for implicit NULL checks for compressed oops.
2849           //
2850           // The original code after Optimize()
2851           //
2852           //    LoadN memory, narrow_oop_reg
2853           //    decode narrow_oop_reg, base_reg
2854           //    CmpP base_reg, NULL
2855           //    CastPP base_reg // NotNull
2856           //    Load [base_reg + offset], val_reg
2857           //
2858           // after these transformations will be
2859           //
2860           //    LoadN memory, narrow_oop_reg
2861           //    CmpN narrow_oop_reg, NULL
2862           //    decode_not_null narrow_oop_reg, base_reg
2863           //    Load [base_reg + offset], val_reg
2864           //
2865           // and the uncommon path (== NULL) will use narrow_oop_reg directly
2866           // since narrow oops can be used in debug info now (see the code in
2867           // final_graph_reshaping_walk()).
2868           //
2869           // At the end the code will be matched to
2870           // on x86:
2871           //
2872           //    Load_narrow_oop memory, narrow_oop_reg
2873           //    Load [R12 + narrow_oop_reg<<3 + offset], val_reg
2874           //    NullCheck narrow_oop_reg
2875           //
2876           // and on sparc:
2877           //
2878           //    Load_narrow_oop memory, narrow_oop_reg
2879           //    decode_not_null narrow_oop_reg, base_reg
2880           //    Load [base_reg + offset], val_reg
2881           //    NullCheck base_reg
2882           //
2883         } else if (t->isa_oopptr()) {
2884           new_in2 = ConNode::make(this, t->make_narrowoop());
2885         } else if (t->isa_klassptr()) {
2886           new_in2 = ConNode::make(this, t->make_narrowklass());
2887         }
2888       }
2889       if (new_in2 != NULL) {
2890         Node* cmpN = new CmpNNode(in1->in(1), new_in2);
2891         n->subsume_by(cmpN, this);
2892         if (in1->outcnt() == 0) {
2893           in1->disconnect_inputs(NULL, this);
2894         }
2895         if (in2->outcnt() == 0) {
2896           in2->disconnect_inputs(NULL, this);
2897         }
2898       }
2899     }
2900     break;
2901 
2902   case Op_DecodeN:
2903   case Op_DecodeNKlass:
2904     assert(!n->in(1)->is_EncodeNarrowPtr(), "should be optimized out");
2905     // DecodeN could be pinned when it can't be fold into
2906     // an address expression, see the code for Op_CastPP above.
2907     assert(n->in(0) == NULL || (UseCompressedOops && !Matcher::narrow_oop_use_complex_address()), "no control");
2908     break;
2909 
2910   case Op_EncodeP:
2911   case Op_EncodePKlass: {
2912     Node* in1 = n->in(1);
2913     if (in1->is_DecodeNarrowPtr()) {
2914       n->subsume_by(in1->in(1), this);
2915     } else if (in1->Opcode() == Op_ConP) {
2916       const Type* t = in1->bottom_type();
2917       if (t == TypePtr::NULL_PTR) {
2918         assert(t->isa_oopptr(), "null klass?");
2919         n->subsume_by(ConNode::make(this, TypeNarrowOop::NULL_PTR), this);
2920       } else if (t->isa_oopptr()) {
2921         n->subsume_by(ConNode::make(this, t->make_narrowoop()), this);
2922       } else if (t->isa_klassptr()) {
2923         n->subsume_by(ConNode::make(this, t->make_narrowklass()), this);
2924       }
2925     }
2926     if (in1->outcnt() == 0) {
2927       in1->disconnect_inputs(NULL, this);
2928     }
2929     break;
2930   }
2931 
2932   case Op_Proj: {
2933     if (OptimizeStringConcat) {
2934       ProjNode* p = n->as_Proj();
2935       if (p->_is_io_use) {
2936         // Separate projections were used for the exception path which
2937         // are normally removed by a late inline.  If it wasn't inlined
2938         // then they will hang around and should just be replaced with
2939         // the original one.
2940         Node* proj = NULL;
2941         // Replace with just one
2942         for (SimpleDUIterator i(p->in(0)); i.has_next(); i.next()) {
2943           Node *use = i.get();
2944           if (use->is_Proj() && p != use && use->as_Proj()->_con == p->_con) {
2945             proj = use;
2946             break;
2947           }
2948         }
2949         assert(proj != NULL, "must be found");
2950         p->subsume_by(proj, this);
2951       }
2952     }
2953     break;
2954   }
2955 
2956   case Op_Phi:
2957     if (n->as_Phi()->bottom_type()->isa_narrowoop() || n->as_Phi()->bottom_type()->isa_narrowklass()) {
2958       // The EncodeP optimization may create Phi with the same edges
2959       // for all paths. It is not handled well by Register Allocator.
2960       Node* unique_in = n->in(1);
2961       assert(unique_in != NULL, "");
2962       uint cnt = n->req();
2963       for (uint i = 2; i < cnt; i++) {
2964         Node* m = n->in(i);
2965         assert(m != NULL, "");
2966         if (unique_in != m)
2967           unique_in = NULL;
2968       }
2969       if (unique_in != NULL) {
2970         n->subsume_by(unique_in, this);
2971       }
2972     }
2973     break;
2974 
2975 #endif
2976 
2977   case Op_ModI:
2978     if (UseDivMod) {
2979       // Check if a%b and a/b both exist
2980       Node* d = n->find_similar(Op_DivI);
2981       if (d) {
2982         // Replace them with a fused divmod if supported
2983         if (Matcher::has_match_rule(Op_DivModI)) {
2984           DivModINode* divmod = DivModINode::make(this, n);
2985           d->subsume_by(divmod->div_proj(), this);
2986           n->subsume_by(divmod->mod_proj(), this);
2987         } else {
2988           // replace a%b with a-((a/b)*b)
2989           Node* mult = new MulINode(d, d->in(2));
2990           Node* sub  = new SubINode(d->in(1), mult);
2991           n->subsume_by(sub, this);
2992         }
2993       }
2994     }
2995     break;
2996 
2997   case Op_ModL:
2998     if (UseDivMod) {
2999       // Check if a%b and a/b both exist
3000       Node* d = n->find_similar(Op_DivL);
3001       if (d) {
3002         // Replace them with a fused divmod if supported
3003         if (Matcher::has_match_rule(Op_DivModL)) {
3004           DivModLNode* divmod = DivModLNode::make(this, n);
3005           d->subsume_by(divmod->div_proj(), this);
3006           n->subsume_by(divmod->mod_proj(), this);
3007         } else {
3008           // replace a%b with a-((a/b)*b)
3009           Node* mult = new MulLNode(d, d->in(2));
3010           Node* sub  = new SubLNode(d->in(1), mult);
3011           n->subsume_by(sub, this);
3012         }
3013       }
3014     }
3015     break;
3016 
3017   case Op_LoadVector:
3018   case Op_StoreVector:
3019     break;
3020 
3021   case Op_PackB:
3022   case Op_PackS:
3023   case Op_PackI:
3024   case Op_PackF:
3025   case Op_PackL:
3026   case Op_PackD:
3027     if (n->req()-1 > 2) {
3028       // Replace many operand PackNodes with a binary tree for matching
3029       PackNode* p = (PackNode*) n;
3030       Node* btp = p->binary_tree_pack(this, 1, n->req());
3031       n->subsume_by(btp, this);
3032     }
3033     break;
3034   case Op_Loop:
3035   case Op_CountedLoop:
3036     if (n->as_Loop()->is_inner_loop()) {
3037       frc.inc_inner_loop_count();
3038     }
3039     break;
3040   case Op_LShiftI:
3041   case Op_RShiftI:
3042   case Op_URShiftI:
3043   case Op_LShiftL:
3044   case Op_RShiftL:
3045   case Op_URShiftL:
3046     if (Matcher::need_masked_shift_count) {
3047       // The cpu's shift instructions don't restrict the count to the
3048       // lower 5/6 bits. We need to do the masking ourselves.
3049       Node* in2 = n->in(2);
3050       juint mask = (n->bottom_type() == TypeInt::INT) ? (BitsPerInt - 1) : (BitsPerLong - 1);
3051       const TypeInt* t = in2->find_int_type();
3052       if (t != NULL && t->is_con()) {
3053         juint shift = t->get_con();
3054         if (shift > mask) { // Unsigned cmp
3055           n->set_req(2, ConNode::make(this, TypeInt::make(shift & mask)));
3056         }
3057       } else {
3058         if (t == NULL || t->_lo < 0 || t->_hi > (int)mask) {
3059           Node* shift = new AndINode(in2, ConNode::make(this, TypeInt::make(mask)));
3060           n->set_req(2, shift);
3061         }
3062       }
3063       if (in2->outcnt() == 0) { // Remove dead node
3064         in2->disconnect_inputs(NULL, this);
3065       }
3066     }
3067     break;
3068   case Op_MemBarStoreStore:
3069   case Op_MemBarRelease:
3070     // Break the link with AllocateNode: it is no longer useful and
3071     // confuses register allocation.
3072     if (n->req() > MemBarNode::Precedent) {
3073       n->set_req(MemBarNode::Precedent, top());
3074     }
3075     break;
3076   default:
3077     assert( !n->is_Call(), "" );
3078     assert( !n->is_Mem(), "" );
3079     break;
3080   }
3081 
3082   // Collect CFG split points
3083   if (n->is_MultiBranch())
3084     frc._tests.push(n);
3085 }
3086 
3087 //------------------------------final_graph_reshaping_walk---------------------
3088 // Replacing Opaque nodes with their input in final_graph_reshaping_impl(),
3089 // requires that the walk visits a node's inputs before visiting the node.
3090 void Compile::final_graph_reshaping_walk( Node_Stack &nstack, Node *root, Final_Reshape_Counts &frc ) {
3091   ResourceArea *area = Thread::current()->resource_area();
3092   Unique_Node_List sfpt(area);
3093 
3094   frc._visited.set(root->_idx); // first, mark node as visited
3095   uint cnt = root->req();
3096   Node *n = root;
3097   uint  i = 0;
3098   while (true) {
3099     if (i < cnt) {
3100       // Place all non-visited non-null inputs onto stack
3101       Node* m = n->in(i);
3102       ++i;
3103       if (m != NULL && !frc._visited.test_set(m->_idx)) {
3104         if (m->is_SafePoint() && m->as_SafePoint()->jvms() != NULL) {
3105           // compute worst case interpreter size in case of a deoptimization
3106           update_interpreter_frame_size(m->as_SafePoint()->jvms()->interpreter_frame_size());
3107 
3108           sfpt.push(m);
3109         }
3110         cnt = m->req();
3111         nstack.push(n, i); // put on stack parent and next input's index
3112         n = m;
3113         i = 0;
3114       }
3115     } else {
3116       // Now do post-visit work
3117       final_graph_reshaping_impl( n, frc );
3118       if (nstack.is_empty())
3119         break;             // finished
3120       n = nstack.node();   // Get node from stack
3121       cnt = n->req();
3122       i = nstack.index();
3123       nstack.pop();        // Shift to the next node on stack
3124     }
3125   }
3126 
3127   // Skip next transformation if compressed oops are not used.
3128   if ((UseCompressedOops && !Matcher::gen_narrow_oop_implicit_null_checks()) ||
3129       (!UseCompressedOops && !UseCompressedClassPointers))
3130     return;
3131 
3132   // Go over safepoints nodes to skip DecodeN/DecodeNKlass nodes for debug edges.
3133   // It could be done for an uncommon traps or any safepoints/calls
3134   // if the DecodeN/DecodeNKlass node is referenced only in a debug info.
3135   while (sfpt.size() > 0) {
3136     n = sfpt.pop();
3137     JVMState *jvms = n->as_SafePoint()->jvms();
3138     assert(jvms != NULL, "sanity");
3139     int start = jvms->debug_start();
3140     int end   = n->req();
3141     bool is_uncommon = (n->is_CallStaticJava() &&
3142                         n->as_CallStaticJava()->uncommon_trap_request() != 0);
3143     for (int j = start; j < end; j++) {
3144       Node* in = n->in(j);
3145       if (in->is_DecodeNarrowPtr()) {
3146         bool safe_to_skip = true;
3147         if (!is_uncommon ) {
3148           // Is it safe to skip?
3149           for (uint i = 0; i < in->outcnt(); i++) {
3150             Node* u = in->raw_out(i);
3151             if (!u->is_SafePoint() ||
3152                  u->is_Call() && u->as_Call()->has_non_debug_use(n)) {
3153               safe_to_skip = false;
3154             }
3155           }
3156         }
3157         if (safe_to_skip) {
3158           n->set_req(j, in->in(1));
3159         }
3160         if (in->outcnt() == 0) {
3161           in->disconnect_inputs(NULL, this);
3162         }
3163       }
3164     }
3165   }
3166 }
3167 
3168 //------------------------------final_graph_reshaping--------------------------
3169 // Final Graph Reshaping.
3170 //
3171 // (1) Clone simple inputs to uncommon calls, so they can be scheduled late
3172 //     and not commoned up and forced early.  Must come after regular
3173 //     optimizations to avoid GVN undoing the cloning.  Clone constant
3174 //     inputs to Loop Phis; these will be split by the allocator anyways.
3175 //     Remove Opaque nodes.
3176 // (2) Move last-uses by commutative operations to the left input to encourage
3177 //     Intel update-in-place two-address operations and better register usage
3178 //     on RISCs.  Must come after regular optimizations to avoid GVN Ideal
3179 //     calls canonicalizing them back.
3180 // (3) Count the number of double-precision FP ops, single-precision FP ops
3181 //     and call sites.  On Intel, we can get correct rounding either by
3182 //     forcing singles to memory (requires extra stores and loads after each
3183 //     FP bytecode) or we can set a rounding mode bit (requires setting and
3184 //     clearing the mode bit around call sites).  The mode bit is only used
3185 //     if the relative frequency of single FP ops to calls is low enough.
3186 //     This is a key transform for SPEC mpeg_audio.
3187 // (4) Detect infinite loops; blobs of code reachable from above but not
3188 //     below.  Several of the Code_Gen algorithms fail on such code shapes,
3189 //     so we simply bail out.  Happens a lot in ZKM.jar, but also happens
3190 //     from time to time in other codes (such as -Xcomp finalizer loops, etc).
3191 //     Detection is by looking for IfNodes where only 1 projection is
3192 //     reachable from below or CatchNodes missing some targets.
3193 // (5) Assert for insane oop offsets in debug mode.
3194 
3195 bool Compile::final_graph_reshaping() {
3196   // an infinite loop may have been eliminated by the optimizer,
3197   // in which case the graph will be empty.
3198   if (root()->req() == 1) {
3199     record_method_not_compilable("trivial infinite loop");
3200     return true;
3201   }
3202 
3203   // Expensive nodes have their control input set to prevent the GVN
3204   // from freely commoning them. There's no GVN beyond this point so
3205   // no need to keep the control input. We want the expensive nodes to
3206   // be freely moved to the least frequent code path by gcm.
3207   assert(OptimizeExpensiveOps || expensive_count() == 0, "optimization off but list non empty?");
3208   for (int i = 0; i < expensive_count(); i++) {
3209     _expensive_nodes->at(i)->set_req(0, NULL);
3210   }
3211 
3212   Final_Reshape_Counts frc;
3213 
3214   // Visit everybody reachable!
3215   // Allocate stack of size C->unique()/2 to avoid frequent realloc
3216   Node_Stack nstack(unique() >> 1);
3217   final_graph_reshaping_walk(nstack, root(), frc);
3218 
3219   // Check for unreachable (from below) code (i.e., infinite loops).
3220   for( uint i = 0; i < frc._tests.size(); i++ ) {
3221     MultiBranchNode *n = frc._tests[i]->as_MultiBranch();
3222     // Get number of CFG targets.
3223     // Note that PCTables include exception targets after calls.
3224     uint required_outcnt = n->required_outcnt();
3225     if (n->outcnt() != required_outcnt) {
3226       // Check for a few special cases.  Rethrow Nodes never take the
3227       // 'fall-thru' path, so expected kids is 1 less.
3228       if (n->is_PCTable() && n->in(0) && n->in(0)->in(0)) {
3229         if (n->in(0)->in(0)->is_Call()) {
3230           CallNode *call = n->in(0)->in(0)->as_Call();
3231           if (call->entry_point() == OptoRuntime::rethrow_stub()) {
3232             required_outcnt--;      // Rethrow always has 1 less kid
3233           } else if (call->req() > TypeFunc::Parms &&
3234                      call->is_CallDynamicJava()) {
3235             // Check for null receiver. In such case, the optimizer has
3236             // detected that the virtual call will always result in a null
3237             // pointer exception. The fall-through projection of this CatchNode
3238             // will not be populated.
3239             Node *arg0 = call->in(TypeFunc::Parms);
3240             if (arg0->is_Type() &&
3241                 arg0->as_Type()->type()->higher_equal(TypePtr::NULL_PTR)) {
3242               required_outcnt--;
3243             }
3244           } else if (call->entry_point() == OptoRuntime::new_array_Java() &&
3245                      call->req() > TypeFunc::Parms+1 &&
3246                      call->is_CallStaticJava()) {
3247             // Check for negative array length. In such case, the optimizer has
3248             // detected that the allocation attempt will always result in an
3249             // exception. There is no fall-through projection of this CatchNode .
3250             Node *arg1 = call->in(TypeFunc::Parms+1);
3251             if (arg1->is_Type() &&
3252                 arg1->as_Type()->type()->join(TypeInt::POS)->empty()) {
3253               required_outcnt--;
3254             }
3255           }
3256         }
3257       }
3258       // Recheck with a better notion of 'required_outcnt'
3259       if (n->outcnt() != required_outcnt) {
3260         record_method_not_compilable("malformed control flow");
3261         return true;            // Not all targets reachable!
3262       }
3263     }
3264     // Check that I actually visited all kids.  Unreached kids
3265     // must be infinite loops.
3266     for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++)
3267       if (!frc._visited.test(n->fast_out(j)->_idx)) {
3268         record_method_not_compilable("infinite loop");
3269         return true;            // Found unvisited kid; must be unreach
3270       }
3271   }
3272 
3273   // If original bytecodes contained a mixture of floats and doubles
3274   // check if the optimizer has made it homogenous, item (3).
3275   if( Use24BitFPMode && Use24BitFP && UseSSE == 0 &&
3276       frc.get_float_count() > 32 &&
3277       frc.get_double_count() == 0 &&
3278       (10 * frc.get_call_count() < frc.get_float_count()) ) {
3279     set_24_bit_selection_and_mode( false,  true );
3280   }
3281 
3282   set_java_calls(frc.get_java_call_count());
3283   set_inner_loops(frc.get_inner_loop_count());
3284 
3285   // No infinite loops, no reason to bail out.
3286   return false;
3287 }
3288 
3289 //-----------------------------too_many_traps----------------------------------
3290 // Report if there are too many traps at the current method and bci.
3291 // Return true if there was a trap, and/or PerMethodTrapLimit is exceeded.
3292 bool Compile::too_many_traps(ciMethod* method,
3293                              int bci,
3294                              Deoptimization::DeoptReason reason) {
3295   ciMethodData* md = method->method_data();
3296   if (md->is_empty()) {
3297     // Assume the trap has not occurred, or that it occurred only
3298     // because of a transient condition during start-up in the interpreter.
3299     return false;
3300   }
3301   ciMethod* m = Deoptimization::reason_is_speculate(reason) ? this->method() : NULL;
3302   if (md->has_trap_at(bci, m, reason) != 0) {
3303     // Assume PerBytecodeTrapLimit==0, for a more conservative heuristic.
3304     // Also, if there are multiple reasons, or if there is no per-BCI record,
3305     // assume the worst.
3306     if (log())
3307       log()->elem("observe trap='%s' count='%d'",
3308                   Deoptimization::trap_reason_name(reason),
3309                   md->trap_count(reason));
3310     return true;
3311   } else {
3312     // Ignore method/bci and see if there have been too many globally.
3313     return too_many_traps(reason, md);
3314   }
3315 }
3316 
3317 // Less-accurate variant which does not require a method and bci.
3318 bool Compile::too_many_traps(Deoptimization::DeoptReason reason,
3319                              ciMethodData* logmd) {
3320   if (trap_count(reason) >= Deoptimization::per_method_trap_limit(reason)) {
3321     // Too many traps globally.
3322     // Note that we use cumulative trap_count, not just md->trap_count.
3323     if (log()) {
3324       int mcount = (logmd == NULL)? -1: (int)logmd->trap_count(reason);
3325       log()->elem("observe trap='%s' count='0' mcount='%d' ccount='%d'",
3326                   Deoptimization::trap_reason_name(reason),
3327                   mcount, trap_count(reason));
3328     }
3329     return true;
3330   } else {
3331     // The coast is clear.
3332     return false;
3333   }
3334 }
3335 
3336 //--------------------------too_many_recompiles--------------------------------
3337 // Report if there are too many recompiles at the current method and bci.
3338 // Consults PerBytecodeRecompilationCutoff and PerMethodRecompilationCutoff.
3339 // Is not eager to return true, since this will cause the compiler to use
3340 // Action_none for a trap point, to avoid too many recompilations.
3341 bool Compile::too_many_recompiles(ciMethod* method,
3342                                   int bci,
3343                                   Deoptimization::DeoptReason reason) {
3344   ciMethodData* md = method->method_data();
3345   if (md->is_empty()) {
3346     // Assume the trap has not occurred, or that it occurred only
3347     // because of a transient condition during start-up in the interpreter.
3348     return false;
3349   }
3350   // Pick a cutoff point well within PerBytecodeRecompilationCutoff.
3351   uint bc_cutoff = (uint) PerBytecodeRecompilationCutoff / 8;
3352   uint m_cutoff  = (uint) PerMethodRecompilationCutoff / 2 + 1;  // not zero
3353   Deoptimization::DeoptReason per_bc_reason
3354     = Deoptimization::reason_recorded_per_bytecode_if_any(reason);
3355   ciMethod* m = Deoptimization::reason_is_speculate(reason) ? this->method() : NULL;
3356   if ((per_bc_reason == Deoptimization::Reason_none
3357        || md->has_trap_at(bci, m, reason) != 0)
3358       // The trap frequency measure we care about is the recompile count:
3359       && md->trap_recompiled_at(bci, m)
3360       && md->overflow_recompile_count() >= bc_cutoff) {
3361     // Do not emit a trap here if it has already caused recompilations.
3362     // Also, if there are multiple reasons, or if there is no per-BCI record,
3363     // assume the worst.
3364     if (log())
3365       log()->elem("observe trap='%s recompiled' count='%d' recompiles2='%d'",
3366                   Deoptimization::trap_reason_name(reason),
3367                   md->trap_count(reason),
3368                   md->overflow_recompile_count());
3369     return true;
3370   } else if (trap_count(reason) != 0
3371              && decompile_count() >= m_cutoff) {
3372     // Too many recompiles globally, and we have seen this sort of trap.
3373     // Use cumulative decompile_count, not just md->decompile_count.
3374     if (log())
3375       log()->elem("observe trap='%s' count='%d' mcount='%d' decompiles='%d' mdecompiles='%d'",
3376                   Deoptimization::trap_reason_name(reason),
3377                   md->trap_count(reason), trap_count(reason),
3378                   md->decompile_count(), decompile_count());
3379     return true;
3380   } else {
3381     // The coast is clear.
3382     return false;
3383   }
3384 }
3385 
3386 // Compute when not to trap. Used by matching trap based nodes and
3387 // NullCheck optimization.
3388 void Compile::set_allowed_deopt_reasons() {
3389   _allowed_reasons = 0;
3390   if (is_method_compilation()) {
3391     for (int rs = (int)Deoptimization::Reason_none+1; rs < Compile::trapHistLength; rs++) {
3392       assert(rs < BitsPerInt, "recode bit map");
3393       if (!too_many_traps((Deoptimization::DeoptReason) rs)) {
3394         _allowed_reasons |= nth_bit(rs);
3395       }
3396     }
3397   }
3398 }
3399 
3400 #ifndef PRODUCT
3401 //------------------------------verify_graph_edges---------------------------
3402 // Walk the Graph and verify that there is a one-to-one correspondence
3403 // between Use-Def edges and Def-Use edges in the graph.
3404 void Compile::verify_graph_edges(bool no_dead_code) {
3405   if (VerifyGraphEdges) {
3406     ResourceArea *area = Thread::current()->resource_area();
3407     Unique_Node_List visited(area);
3408     // Call recursive graph walk to check edges
3409     _root->verify_edges(visited);
3410     if (no_dead_code) {
3411       // Now make sure that no visited node is used by an unvisited node.
3412       bool dead_nodes = false;
3413       Unique_Node_List checked(area);
3414       while (visited.size() > 0) {
3415         Node* n = visited.pop();
3416         checked.push(n);
3417         for (uint i = 0; i < n->outcnt(); i++) {
3418           Node* use = n->raw_out(i);
3419           if (checked.member(use))  continue;  // already checked
3420           if (visited.member(use))  continue;  // already in the graph
3421           if (use->is_Con())        continue;  // a dead ConNode is OK
3422           // At this point, we have found a dead node which is DU-reachable.
3423           if (!dead_nodes) {
3424             tty->print_cr("*** Dead nodes reachable via DU edges:");
3425             dead_nodes = true;
3426           }
3427           use->dump(2);
3428           tty->print_cr("---");
3429           checked.push(use);  // No repeats; pretend it is now checked.
3430         }
3431       }
3432       assert(!dead_nodes, "using nodes must be reachable from root");
3433     }
3434   }
3435 }
3436 
3437 // Verify GC barriers consistency
3438 // Currently supported:
3439 // - G1 pre-barriers (see GraphKit::g1_write_barrier_pre())
3440 void Compile::verify_barriers() {
3441   if (UseG1GC) {
3442     // Verify G1 pre-barriers
3443     const int marking_offset = in_bytes(JavaThread::satb_mark_queue_offset() + PtrQueue::byte_offset_of_active());
3444 
3445     ResourceArea *area = Thread::current()->resource_area();
3446     Unique_Node_List visited(area);
3447     Node_List worklist(area);
3448     // We're going to walk control flow backwards starting from the Root
3449     worklist.push(_root);
3450     while (worklist.size() > 0) {
3451       Node* x = worklist.pop();
3452       if (x == NULL || x == top()) continue;
3453       if (visited.member(x)) {
3454         continue;
3455       } else {
3456         visited.push(x);
3457       }
3458 
3459       if (x->is_Region()) {
3460         for (uint i = 1; i < x->req(); i++) {
3461           worklist.push(x->in(i));
3462         }
3463       } else {
3464         worklist.push(x->in(0));
3465         // We are looking for the pattern:
3466         //                            /->ThreadLocal
3467         // If->Bool->CmpI->LoadB->AddP->ConL(marking_offset)
3468         //              \->ConI(0)
3469         // We want to verify that the If and the LoadB have the same control
3470         // See GraphKit::g1_write_barrier_pre()
3471         if (x->is_If()) {
3472           IfNode *iff = x->as_If();
3473           if (iff->in(1)->is_Bool() && iff->in(1)->in(1)->is_Cmp()) {
3474             CmpNode *cmp = iff->in(1)->in(1)->as_Cmp();
3475             if (cmp->Opcode() == Op_CmpI && cmp->in(2)->is_Con() && cmp->in(2)->bottom_type()->is_int()->get_con() == 0
3476                 && cmp->in(1)->is_Load()) {
3477               LoadNode* load = cmp->in(1)->as_Load();
3478               if (load->Opcode() == Op_LoadB && load->in(2)->is_AddP() && load->in(2)->in(2)->Opcode() == Op_ThreadLocal
3479                   && load->in(2)->in(3)->is_Con()
3480                   && load->in(2)->in(3)->bottom_type()->is_intptr_t()->get_con() == marking_offset) {
3481 
3482                 Node* if_ctrl = iff->in(0);
3483                 Node* load_ctrl = load->in(0);
3484 
3485                 if (if_ctrl != load_ctrl) {
3486                   // Skip possible CProj->NeverBranch in infinite loops
3487                   if ((if_ctrl->is_Proj() && if_ctrl->Opcode() == Op_CProj)
3488                       && (if_ctrl->in(0)->is_MultiBranch() && if_ctrl->in(0)->Opcode() == Op_NeverBranch)) {
3489                     if_ctrl = if_ctrl->in(0)->in(0);
3490                   }
3491                 }
3492                 assert(load_ctrl != NULL && if_ctrl == load_ctrl, "controls must match");
3493               }
3494             }
3495           }
3496         }
3497       }
3498     }
3499   }
3500 }
3501 
3502 #endif
3503 
3504 // The Compile object keeps track of failure reasons separately from the ciEnv.
3505 // This is required because there is not quite a 1-1 relation between the
3506 // ciEnv and its compilation task and the Compile object.  Note that one
3507 // ciEnv might use two Compile objects, if C2Compiler::compile_method decides
3508 // to backtrack and retry without subsuming loads.  Other than this backtracking
3509 // behavior, the Compile's failure reason is quietly copied up to the ciEnv
3510 // by the logic in C2Compiler.
3511 void Compile::record_failure(const char* reason) {
3512   if (log() != NULL) {
3513     log()->elem("failure reason='%s' phase='compile'", reason);
3514   }
3515   if (_failure_reason == NULL) {
3516     // Record the first failure reason.
3517     _failure_reason = reason;
3518   }
3519 
3520   EventCompilerFailure event;
3521   if (event.should_commit()) {
3522     event.set_compileID(Compile::compile_id());
3523     event.set_failure(reason);
3524     event.commit();
3525   }
3526 
3527   if (!C->failure_reason_is(C2Compiler::retry_no_subsuming_loads())) {
3528     C->print_method(PHASE_FAILURE);
3529   }
3530   _root = NULL;  // flush the graph, too
3531 }
3532 
3533 Compile::TracePhase::TracePhase(const char* name, elapsedTimer* accumulator, bool dolog)
3534   : TraceTime(NULL, accumulator, false NOT_PRODUCT( || TimeCompiler ), false),
3535     _phase_name(name), _dolog(dolog)
3536 {
3537   if (dolog) {
3538     C = Compile::current();
3539     _log = C->log();
3540   } else {
3541     C = NULL;
3542     _log = NULL;
3543   }
3544   if (_log != NULL) {
3545     _log->begin_head("phase name='%s' nodes='%d' live='%d'", _phase_name, C->unique(), C->live_nodes());
3546     _log->stamp();
3547     _log->end_head();
3548   }
3549 }
3550 
3551 Compile::TracePhase::~TracePhase() {
3552 
3553   C = Compile::current();
3554   if (_dolog) {
3555     _log = C->log();
3556   } else {
3557     _log = NULL;
3558   }
3559 
3560 #ifdef ASSERT
3561   if (PrintIdealNodeCount) {
3562     tty->print_cr("phase name='%s' nodes='%d' live='%d' live_graph_walk='%d'",
3563                   _phase_name, C->unique(), C->live_nodes(), C->count_live_nodes_by_graph_walk());
3564   }
3565 
3566   if (VerifyIdealNodeCount) {
3567     Compile::current()->print_missing_nodes();
3568   }
3569 #endif
3570 
3571   if (_log != NULL) {
3572     _log->done("phase name='%s' nodes='%d' live='%d'", _phase_name, C->unique(), C->live_nodes());
3573   }
3574 }
3575 
3576 //=============================================================================
3577 // Two Constant's are equal when the type and the value are equal.
3578 bool Compile::Constant::operator==(const Constant& other) {
3579   if (type()          != other.type()         )  return false;
3580   if (can_be_reused() != other.can_be_reused())  return false;
3581   // For floating point values we compare the bit pattern.
3582   switch (type()) {
3583   case T_FLOAT:   return (_v._value.i == other._v._value.i);
3584   case T_LONG:
3585   case T_DOUBLE:  return (_v._value.j == other._v._value.j);
3586   case T_OBJECT:
3587   case T_ADDRESS: return (_v._value.l == other._v._value.l);
3588   case T_VOID:    return (_v._value.l == other._v._value.l);  // jump-table entries
3589   case T_METADATA: return (_v._metadata == other._v._metadata);
3590   default: ShouldNotReachHere();
3591   }
3592   return false;
3593 }
3594 
3595 static int type_to_size_in_bytes(BasicType t) {
3596   switch (t) {
3597   case T_LONG:    return sizeof(jlong  );
3598   case T_FLOAT:   return sizeof(jfloat );
3599   case T_DOUBLE:  return sizeof(jdouble);
3600   case T_METADATA: return sizeof(Metadata*);
3601     // We use T_VOID as marker for jump-table entries (labels) which
3602     // need an internal word relocation.
3603   case T_VOID:
3604   case T_ADDRESS:
3605   case T_OBJECT:  return sizeof(jobject);
3606   }
3607 
3608   ShouldNotReachHere();
3609   return -1;
3610 }
3611 
3612 int Compile::ConstantTable::qsort_comparator(Constant* a, Constant* b) {
3613   // sort descending
3614   if (a->freq() > b->freq())  return -1;
3615   if (a->freq() < b->freq())  return  1;
3616   return 0;
3617 }
3618 
3619 void Compile::ConstantTable::calculate_offsets_and_size() {
3620   // First, sort the array by frequencies.
3621   _constants.sort(qsort_comparator);
3622 
3623 #ifdef ASSERT
3624   // Make sure all jump-table entries were sorted to the end of the
3625   // array (they have a negative frequency).
3626   bool found_void = false;
3627   for (int i = 0; i < _constants.length(); i++) {
3628     Constant con = _constants.at(i);
3629     if (con.type() == T_VOID)
3630       found_void = true;  // jump-tables
3631     else
3632       assert(!found_void, "wrong sorting");
3633   }
3634 #endif
3635 
3636   int offset = 0;
3637   for (int i = 0; i < _constants.length(); i++) {
3638     Constant* con = _constants.adr_at(i);
3639 
3640     // Align offset for type.
3641     int typesize = type_to_size_in_bytes(con->type());
3642     offset = align_size_up(offset, typesize);
3643     con->set_offset(offset);   // set constant's offset
3644 
3645     if (con->type() == T_VOID) {
3646       MachConstantNode* n = (MachConstantNode*) con->get_jobject();
3647       offset = offset + typesize * n->outcnt();  // expand jump-table
3648     } else {
3649       offset = offset + typesize;
3650     }
3651   }
3652 
3653   // Align size up to the next section start (which is insts; see
3654   // CodeBuffer::align_at_start).
3655   assert(_size == -1, "already set?");
3656   _size = align_size_up(offset, CodeEntryAlignment);
3657 }
3658 
3659 void Compile::ConstantTable::emit(CodeBuffer& cb) {
3660   MacroAssembler _masm(&cb);
3661   for (int i = 0; i < _constants.length(); i++) {
3662     Constant con = _constants.at(i);
3663     address constant_addr;
3664     switch (con.type()) {
3665     case T_LONG:   constant_addr = _masm.long_constant(  con.get_jlong()  ); break;
3666     case T_FLOAT:  constant_addr = _masm.float_constant( con.get_jfloat() ); break;
3667     case T_DOUBLE: constant_addr = _masm.double_constant(con.get_jdouble()); break;
3668     case T_OBJECT: {
3669       jobject obj = con.get_jobject();
3670       int oop_index = _masm.oop_recorder()->find_index(obj);
3671       constant_addr = _masm.address_constant((address) obj, oop_Relocation::spec(oop_index));
3672       break;
3673     }
3674     case T_ADDRESS: {
3675       address addr = (address) con.get_jobject();
3676       constant_addr = _masm.address_constant(addr);
3677       break;
3678     }
3679     // We use T_VOID as marker for jump-table entries (labels) which
3680     // need an internal word relocation.
3681     case T_VOID: {
3682       MachConstantNode* n = (MachConstantNode*) con.get_jobject();
3683       // Fill the jump-table with a dummy word.  The real value is
3684       // filled in later in fill_jump_table.
3685       address dummy = (address) n;
3686       constant_addr = _masm.address_constant(dummy);
3687       // Expand jump-table
3688       for (uint i = 1; i < n->outcnt(); i++) {
3689         address temp_addr = _masm.address_constant(dummy + i);
3690         assert(temp_addr, "consts section too small");
3691       }
3692       break;
3693     }
3694     case T_METADATA: {
3695       Metadata* obj = con.get_metadata();
3696       int metadata_index = _masm.oop_recorder()->find_index(obj);
3697       constant_addr = _masm.address_constant((address) obj, metadata_Relocation::spec(metadata_index));
3698       break;
3699     }
3700     default: ShouldNotReachHere();
3701     }
3702     assert(constant_addr, "consts section too small");
3703     assert((constant_addr - _masm.code()->consts()->start()) == con.offset(),
3704             err_msg_res("must be: %d == %d", (int) (constant_addr - _masm.code()->consts()->start()), (int)(con.offset())));
3705   }
3706 }
3707 
3708 int Compile::ConstantTable::find_offset(Constant& con) const {
3709   int idx = _constants.find(con);
3710   assert(idx != -1, "constant must be in constant table");
3711   int offset = _constants.at(idx).offset();
3712   assert(offset != -1, "constant table not emitted yet?");
3713   return offset;
3714 }
3715 
3716 void Compile::ConstantTable::add(Constant& con) {
3717   if (con.can_be_reused()) {
3718     int idx = _constants.find(con);
3719     if (idx != -1 && _constants.at(idx).can_be_reused()) {
3720       _constants.adr_at(idx)->inc_freq(con.freq());  // increase the frequency by the current value
3721       return;
3722     }
3723   }
3724   (void) _constants.append(con);
3725 }
3726 
3727 Compile::Constant Compile::ConstantTable::add(MachConstantNode* n, BasicType type, jvalue value) {
3728   Block* b = Compile::current()->cfg()->get_block_for_node(n);
3729   Constant con(type, value, b->_freq);
3730   add(con);
3731   return con;
3732 }
3733 
3734 Compile::Constant Compile::ConstantTable::add(Metadata* metadata) {
3735   Constant con(metadata);
3736   add(con);
3737   return con;
3738 }
3739 
3740 Compile::Constant Compile::ConstantTable::add(MachConstantNode* n, MachOper* oper) {
3741   jvalue value;
3742   BasicType type = oper->type()->basic_type();
3743   switch (type) {
3744   case T_LONG:    value.j = oper->constantL(); break;
3745   case T_FLOAT:   value.f = oper->constantF(); break;
3746   case T_DOUBLE:  value.d = oper->constantD(); break;
3747   case T_OBJECT:
3748   case T_ADDRESS: value.l = (jobject) oper->constant(); break;
3749   case T_METADATA: return add((Metadata*)oper->constant()); break;
3750   default: guarantee(false, err_msg_res("unhandled type: %s", type2name(type)));
3751   }
3752   return add(n, type, value);
3753 }
3754 
3755 Compile::Constant Compile::ConstantTable::add_jump_table(MachConstantNode* n) {
3756   jvalue value;
3757   // We can use the node pointer here to identify the right jump-table
3758   // as this method is called from Compile::Fill_buffer right before
3759   // the MachNodes are emitted and the jump-table is filled (means the
3760   // MachNode pointers do not change anymore).
3761   value.l = (jobject) n;
3762   Constant con(T_VOID, value, next_jump_table_freq(), false);  // Labels of a jump-table cannot be reused.
3763   add(con);
3764   return con;
3765 }
3766 
3767 void Compile::ConstantTable::fill_jump_table(CodeBuffer& cb, MachConstantNode* n, GrowableArray<Label*> labels) const {
3768   // If called from Compile::scratch_emit_size do nothing.
3769   if (Compile::current()->in_scratch_emit_size())  return;
3770 
3771   assert(labels.is_nonempty(), "must be");
3772   assert((uint) labels.length() == n->outcnt(), err_msg_res("must be equal: %d == %d", labels.length(), n->outcnt()));
3773 
3774   // Since MachConstantNode::constant_offset() also contains
3775   // table_base_offset() we need to subtract the table_base_offset()
3776   // to get the plain offset into the constant table.
3777   int offset = n->constant_offset() - table_base_offset();
3778 
3779   MacroAssembler _masm(&cb);
3780   address* jump_table_base = (address*) (_masm.code()->consts()->start() + offset);
3781 
3782   for (uint i = 0; i < n->outcnt(); i++) {
3783     address* constant_addr = &jump_table_base[i];
3784     assert(*constant_addr == (((address) n) + i), err_msg_res("all jump-table entries must contain adjusted node pointer: " INTPTR_FORMAT " == " INTPTR_FORMAT, p2i(*constant_addr), p2i(((address) n) + i)));
3785     *constant_addr = cb.consts()->target(*labels.at(i), (address) constant_addr);
3786     cb.consts()->relocate((address) constant_addr, relocInfo::internal_word_type);
3787   }
3788 }
3789 
3790 // The message about the current inlining is accumulated in
3791 // _print_inlining_stream and transfered into the _print_inlining_list
3792 // once we know whether inlining succeeds or not. For regular
3793 // inlining, messages are appended to the buffer pointed by
3794 // _print_inlining_idx in the _print_inlining_list. For late inlining,
3795 // a new buffer is added after _print_inlining_idx in the list. This
3796 // way we can update the inlining message for late inlining call site
3797 // when the inlining is attempted again.
3798 void Compile::print_inlining_init() {
3799   if (print_inlining() || print_intrinsics()) {
3800     _print_inlining_stream = new stringStream();
3801     _print_inlining_list = new (comp_arena())GrowableArray<PrintInliningBuffer>(comp_arena(), 1, 1, PrintInliningBuffer());
3802   }
3803 }
3804 
3805 void Compile::print_inlining_reinit() {
3806   if (print_inlining() || print_intrinsics()) {
3807     // Re allocate buffer when we change ResourceMark
3808     _print_inlining_stream = new stringStream();
3809   }
3810 }
3811 
3812 void Compile::print_inlining_reset() {
3813   _print_inlining_stream->reset();
3814 }
3815 
3816 void Compile::print_inlining_commit() {
3817   assert(print_inlining() || print_intrinsics(), "PrintInlining off?");
3818   // Transfer the message from _print_inlining_stream to the current
3819   // _print_inlining_list buffer and clear _print_inlining_stream.
3820   _print_inlining_list->at(_print_inlining_idx).ss()->write(_print_inlining_stream->as_string(), _print_inlining_stream->size());
3821   print_inlining_reset();
3822 }
3823 
3824 void Compile::print_inlining_push() {
3825   // Add new buffer to the _print_inlining_list at current position
3826   _print_inlining_idx++;
3827   _print_inlining_list->insert_before(_print_inlining_idx, PrintInliningBuffer());
3828 }
3829 
3830 Compile::PrintInliningBuffer& Compile::print_inlining_current() {
3831   return _print_inlining_list->at(_print_inlining_idx);
3832 }
3833 
3834 void Compile::print_inlining_update(CallGenerator* cg) {
3835   if (print_inlining() || print_intrinsics()) {
3836     if (!cg->is_late_inline()) {
3837       if (print_inlining_current().cg() != NULL) {
3838         print_inlining_push();
3839       }
3840       print_inlining_commit();
3841     } else {
3842       if (print_inlining_current().cg() != cg &&
3843           (print_inlining_current().cg() != NULL ||
3844            print_inlining_current().ss()->size() != 0)) {
3845         print_inlining_push();
3846       }
3847       print_inlining_commit();
3848       print_inlining_current().set_cg(cg);
3849     }
3850   }
3851 }
3852 
3853 void Compile::print_inlining_move_to(CallGenerator* cg) {
3854   // We resume inlining at a late inlining call site. Locate the
3855   // corresponding inlining buffer so that we can update it.
3856   if (print_inlining()) {
3857     for (int i = 0; i < _print_inlining_list->length(); i++) {
3858       if (_print_inlining_list->adr_at(i)->cg() == cg) {
3859         _print_inlining_idx = i;
3860         return;
3861       }
3862     }
3863     ShouldNotReachHere();
3864   }
3865 }
3866 
3867 void Compile::print_inlining_update_delayed(CallGenerator* cg) {
3868   if (print_inlining()) {
3869     assert(_print_inlining_stream->size() > 0, "missing inlining msg");
3870     assert(print_inlining_current().cg() == cg, "wrong entry");
3871     // replace message with new message
3872     _print_inlining_list->at_put(_print_inlining_idx, PrintInliningBuffer());
3873     print_inlining_commit();
3874     print_inlining_current().set_cg(cg);
3875   }
3876 }
3877 
3878 void Compile::print_inlining_assert_ready() {
3879   assert(!_print_inlining || _print_inlining_stream->size() == 0, "loosing data");
3880 }
3881 
3882 void Compile::process_print_inlining() {
3883   bool do_print_inlining = print_inlining() || print_intrinsics();
3884   if (do_print_inlining || log() != NULL) {
3885     // Print inlining message for candidates that we couldn't inline
3886     // for lack of space
3887     for (int i = 0; i < _late_inlines.length(); i++) {
3888       CallGenerator* cg = _late_inlines.at(i);
3889       if (!cg->is_mh_late_inline()) {
3890         const char* msg = "live nodes > LiveNodeCountInliningCutoff";
3891         if (do_print_inlining) {
3892           cg->print_inlining_late(msg);
3893         }
3894         log_late_inline_failure(cg, msg);
3895       }
3896     }
3897   }
3898   if (do_print_inlining) {
3899     ResourceMark rm;
3900     stringStream ss;
3901     for (int i = 0; i < _print_inlining_list->length(); i++) {
3902       ss.print("%s", _print_inlining_list->adr_at(i)->ss()->as_string());
3903     }
3904     size_t end = ss.size();
3905     _print_inlining_output = NEW_ARENA_ARRAY(comp_arena(), char, end+1);
3906     strncpy(_print_inlining_output, ss.base(), end+1);
3907     _print_inlining_output[end] = 0;
3908   }
3909 }
3910 
3911 void Compile::dump_print_inlining() {
3912   if (_print_inlining_output != NULL) {
3913     tty->print_raw(_print_inlining_output);
3914   }
3915 }
3916 
3917 void Compile::log_late_inline(CallGenerator* cg) {
3918   if (log() != NULL) {
3919     log()->head("late_inline method='%d'  inline_id='" JLONG_FORMAT "'", log()->identify(cg->method()),
3920                 cg->unique_id());
3921     JVMState* p = cg->call_node()->jvms();
3922     while (p != NULL) {
3923       log()->elem("jvms bci='%d' method='%d'", p->bci(), log()->identify(p->method()));
3924       p = p->caller();
3925     }
3926     log()->tail("late_inline");
3927   }
3928 }
3929 
3930 void Compile::log_late_inline_failure(CallGenerator* cg, const char* msg) {
3931   log_late_inline(cg);
3932   if (log() != NULL) {
3933     log()->inline_fail(msg);
3934   }
3935 }
3936 
3937 void Compile::log_inline_id(CallGenerator* cg) {
3938   if (log() != NULL) {
3939     // The LogCompilation tool needs a unique way to identify late
3940     // inline call sites. This id must be unique for this call site in
3941     // this compilation. Try to have it unique across compilations as
3942     // well because it can be convenient when grepping through the log
3943     // file.
3944     // Distinguish OSR compilations from others in case CICountOSR is
3945     // on.
3946     jlong id = ((jlong)unique()) + (((jlong)compile_id()) << 33) + (CICountOSR && is_osr_compilation() ? ((jlong)1) << 32 : 0);
3947     cg->set_unique_id(id);
3948     log()->elem("inline_id id='" JLONG_FORMAT "'", id);
3949   }
3950 }
3951 
3952 void Compile::log_inline_failure(const char* msg) {
3953   if (C->log() != NULL) {
3954     C->log()->inline_fail(msg);
3955   }
3956 }
3957 
3958 
3959 // Dump inlining replay data to the stream.
3960 // Don't change thread state and acquire any locks.
3961 void Compile::dump_inline_data(outputStream* out) {
3962   InlineTree* inl_tree = ilt();
3963   if (inl_tree != NULL) {
3964     out->print(" inline %d", inl_tree->count());
3965     inl_tree->dump_replay_data(out);
3966   }
3967 }
3968 
3969 int Compile::cmp_expensive_nodes(Node* n1, Node* n2) {
3970   if (n1->Opcode() < n2->Opcode())      return -1;
3971   else if (n1->Opcode() > n2->Opcode()) return 1;
3972 
3973   assert(n1->req() == n2->req(), err_msg_res("can't compare %s nodes: n1->req() = %d, n2->req() = %d", NodeClassNames[n1->Opcode()], n1->req(), n2->req()));
3974   for (uint i = 1; i < n1->req(); i++) {
3975     if (n1->in(i) < n2->in(i))      return -1;
3976     else if (n1->in(i) > n2->in(i)) return 1;
3977   }
3978 
3979   return 0;
3980 }
3981 
3982 int Compile::cmp_expensive_nodes(Node** n1p, Node** n2p) {
3983   Node* n1 = *n1p;
3984   Node* n2 = *n2p;
3985 
3986   return cmp_expensive_nodes(n1, n2);
3987 }
3988 
3989 void Compile::sort_expensive_nodes() {
3990   if (!expensive_nodes_sorted()) {
3991     _expensive_nodes->sort(cmp_expensive_nodes);
3992   }
3993 }
3994 
3995 bool Compile::expensive_nodes_sorted() const {
3996   for (int i = 1; i < _expensive_nodes->length(); i++) {
3997     if (cmp_expensive_nodes(_expensive_nodes->adr_at(i), _expensive_nodes->adr_at(i-1)) < 0) {
3998       return false;
3999     }
4000   }
4001   return true;
4002 }
4003 
4004 bool Compile::should_optimize_expensive_nodes(PhaseIterGVN &igvn) {
4005   if (_expensive_nodes->length() == 0) {
4006     return false;
4007   }
4008 
4009   assert(OptimizeExpensiveOps, "optimization off?");
4010 
4011   // Take this opportunity to remove dead nodes from the list
4012   int j = 0;
4013   for (int i = 0; i < _expensive_nodes->length(); i++) {
4014     Node* n = _expensive_nodes->at(i);
4015     if (!n->is_unreachable(igvn)) {
4016       assert(n->is_expensive(), "should be expensive");
4017       _expensive_nodes->at_put(j, n);
4018       j++;
4019     }
4020   }
4021   _expensive_nodes->trunc_to(j);
4022 
4023   // Then sort the list so that similar nodes are next to each other
4024   // and check for at least two nodes of identical kind with same data
4025   // inputs.
4026   sort_expensive_nodes();
4027 
4028   for (int i = 0; i < _expensive_nodes->length()-1; i++) {
4029     if (cmp_expensive_nodes(_expensive_nodes->adr_at(i), _expensive_nodes->adr_at(i+1)) == 0) {
4030       return true;
4031     }
4032   }
4033 
4034   return false;
4035 }
4036 
4037 void Compile::cleanup_expensive_nodes(PhaseIterGVN &igvn) {
4038   if (_expensive_nodes->length() == 0) {
4039     return;
4040   }
4041 
4042   assert(OptimizeExpensiveOps, "optimization off?");
4043 
4044   // Sort to bring similar nodes next to each other and clear the
4045   // control input of nodes for which there's only a single copy.
4046   sort_expensive_nodes();
4047 
4048   int j = 0;
4049   int identical = 0;
4050   int i = 0;
4051   bool modified = false;
4052   for (; i < _expensive_nodes->length()-1; i++) {
4053     assert(j <= i, "can't write beyond current index");
4054     if (_expensive_nodes->at(i)->Opcode() == _expensive_nodes->at(i+1)->Opcode()) {
4055       identical++;
4056       _expensive_nodes->at_put(j++, _expensive_nodes->at(i));
4057       continue;
4058     }
4059     if (identical > 0) {
4060       _expensive_nodes->at_put(j++, _expensive_nodes->at(i));
4061       identical = 0;
4062     } else {
4063       Node* n = _expensive_nodes->at(i);
4064       igvn.replace_input_of(n, 0, NULL);
4065       igvn.hash_insert(n);
4066       modified = true;
4067     }
4068   }
4069   if (identical > 0) {
4070     _expensive_nodes->at_put(j++, _expensive_nodes->at(i));
4071   } else if (_expensive_nodes->length() >= 1) {
4072     Node* n = _expensive_nodes->at(i);
4073     igvn.replace_input_of(n, 0, NULL);
4074     igvn.hash_insert(n);
4075     modified = true;
4076   }
4077   _expensive_nodes->trunc_to(j);
4078   if (modified) {
4079     igvn.optimize();
4080   }
4081 }
4082 
4083 void Compile::add_expensive_node(Node * n) {
4084   assert(!_expensive_nodes->contains(n), "duplicate entry in expensive list");
4085   assert(n->is_expensive(), "expensive nodes with non-null control here only");
4086   assert(!n->is_CFG() && !n->is_Mem(), "no cfg or memory nodes here");
4087   if (OptimizeExpensiveOps) {
4088     _expensive_nodes->append(n);
4089   } else {
4090     // Clear control input and let IGVN optimize expensive nodes if
4091     // OptimizeExpensiveOps is off.
4092     n->set_req(0, NULL);
4093   }
4094 }
4095 
4096 /**
4097  * Remove the speculative part of types and clean up the graph
4098  */
4099 void Compile::remove_speculative_types(PhaseIterGVN &igvn) {
4100   if (UseTypeSpeculation) {
4101     Unique_Node_List worklist;
4102     worklist.push(root());
4103     int modified = 0;
4104     // Go over all type nodes that carry a speculative type, drop the
4105     // speculative part of the type and enqueue the node for an igvn
4106     // which may optimize it out.
4107     for (uint next = 0; next < worklist.size(); ++next) {
4108       Node *n  = worklist.at(next);
4109       if (n->is_Type()) {
4110         TypeNode* tn = n->as_Type();
4111         const Type* t = tn->type();
4112         const Type* t_no_spec = t->remove_speculative();
4113         if (t_no_spec != t) {
4114           bool in_hash = igvn.hash_delete(n);
4115           assert(in_hash, "node should be in igvn hash table");
4116           tn->set_type(t_no_spec);
4117           igvn.hash_insert(n);
4118           igvn._worklist.push(n); // give it a chance to go away
4119           modified++;
4120         }
4121       }
4122       uint max = n->len();
4123       for( uint i = 0; i < max; ++i ) {
4124         Node *m = n->in(i);
4125         if (not_a_node(m))  continue;
4126         worklist.push(m);
4127       }
4128     }
4129     // Drop the speculative part of all types in the igvn's type table
4130     igvn.remove_speculative_types();
4131     if (modified > 0) {
4132       igvn.optimize();
4133     }
4134 #ifdef ASSERT
4135     // Verify that after the IGVN is over no speculative type has resurfaced
4136     worklist.clear();
4137     worklist.push(root());
4138     for (uint next = 0; next < worklist.size(); ++next) {
4139       Node *n  = worklist.at(next);
4140       const Type* t = igvn.type_or_null(n);
4141       assert((t == NULL) || (t == t->remove_speculative()), "no more speculative types");
4142       if (n->is_Type()) {
4143         t = n->as_Type()->type();
4144         assert(t == t->remove_speculative(), "no more speculative types");
4145       }
4146       uint max = n->len();
4147       for( uint i = 0; i < max; ++i ) {
4148         Node *m = n->in(i);
4149         if (not_a_node(m))  continue;
4150         worklist.push(m);
4151       }
4152     }
4153     igvn.check_no_speculative_types();
4154 #endif
4155   }
4156 }
4157 
4158 // Auxiliary method to support randomized stressing/fuzzing.
4159 //
4160 // This method can be called the arbitrary number of times, with current count
4161 // as the argument. The logic allows selecting a single candidate from the
4162 // running list of candidates as follows:
4163 //    int count = 0;
4164 //    Cand* selected = null;
4165 //    while(cand = cand->next()) {
4166 //      if (randomized_select(++count)) {
4167 //        selected = cand;
4168 //      }
4169 //    }
4170 //
4171 // Including count equalizes the chances any candidate is "selected".
4172 // This is useful when we don't have the complete list of candidates to choose
4173 // from uniformly. In this case, we need to adjust the randomicity of the
4174 // selection, or else we will end up biasing the selection towards the latter
4175 // candidates.
4176 //
4177 // Quick back-envelope calculation shows that for the list of n candidates
4178 // the equal probability for the candidate to persist as "best" can be
4179 // achieved by replacing it with "next" k-th candidate with the probability
4180 // of 1/k. It can be easily shown that by the end of the run, the
4181 // probability for any candidate is converged to 1/n, thus giving the
4182 // uniform distribution among all the candidates.
4183 //
4184 // We don't care about the domain size as long as (RANDOMIZED_DOMAIN / count) is large.
4185 #define RANDOMIZED_DOMAIN_POW 29
4186 #define RANDOMIZED_DOMAIN (1 << RANDOMIZED_DOMAIN_POW)
4187 #define RANDOMIZED_DOMAIN_MASK ((1 << (RANDOMIZED_DOMAIN_POW + 1)) - 1)
4188 bool Compile::randomized_select(int count) {
4189   assert(count > 0, "only positive");
4190   return (os::random() & RANDOMIZED_DOMAIN_MASK) < (RANDOMIZED_DOMAIN / count);
4191 }