src/share/vm/opto/compile.cpp

Wed, 27 Jan 2016 09:02:51 +0100

author
thartmann
date
Wed, 27 Jan 2016 09:02:51 +0100
changeset 8476
94ec11846b18
parent 8068
c1091733abe6
child 8478
c42cb5db3601
permissions
-rw-r--r--

6675699: need comprehensive fix for unconstrained ConvI2L with narrowed type
Summary: Emit CastII to make narrow ConvI2L dependent on the corresponding range check.
Reviewed-by: kvn, roland

     1 /*
     2  * Copyright (c) 1997, 2015, Oracle and/or its affiliates. All rights reserved.
     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
     4  *
     5  * This code is free software; you can redistribute it and/or modify it
     6  * under the terms of the GNU General Public License version 2 only, as
     7  * published by the Free Software Foundation.
     8  *
     9  * This code is distributed in the hope that it will be useful, but WITHOUT
    10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
    11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
    12  * version 2 for more details (a copy is included in the LICENSE file that
    13  * accompanied this code).
    14  *
    15  * You should have received a copy of the GNU General Public License version
    16  * 2 along with this work; if not, write to the Free Software Foundation,
    17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
    18  *
    19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
    20  * or visit www.oracle.com if you need additional information or have any
    21  * questions.
    22  *
    23  */
    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/compileLog.hpp"
    33 #include "compiler/disassembler.hpp"
    34 #include "compiler/oopMap.hpp"
    35 #include "opto/addnode.hpp"
    36 #include "opto/block.hpp"
    37 #include "opto/c2compiler.hpp"
    38 #include "opto/callGenerator.hpp"
    39 #include "opto/callnode.hpp"
    40 #include "opto/cfgnode.hpp"
    41 #include "opto/chaitin.hpp"
    42 #include "opto/compile.hpp"
    43 #include "opto/connode.hpp"
    44 #include "opto/divnode.hpp"
    45 #include "opto/escape.hpp"
    46 #include "opto/idealGraphPrinter.hpp"
    47 #include "opto/loopnode.hpp"
    48 #include "opto/machnode.hpp"
    49 #include "opto/macro.hpp"
    50 #include "opto/matcher.hpp"
    51 #include "opto/mathexactnode.hpp"
    52 #include "opto/memnode.hpp"
    53 #include "opto/mulnode.hpp"
    54 #include "opto/node.hpp"
    55 #include "opto/opcodes.hpp"
    56 #include "opto/output.hpp"
    57 #include "opto/parse.hpp"
    58 #include "opto/phaseX.hpp"
    59 #include "opto/rootnode.hpp"
    60 #include "opto/runtime.hpp"
    61 #include "opto/stringopts.hpp"
    62 #include "opto/type.hpp"
    63 #include "opto/vectornode.hpp"
    64 #include "runtime/arguments.hpp"
    65 #include "runtime/signature.hpp"
    66 #include "runtime/stubRoutines.hpp"
    67 #include "runtime/timer.hpp"
    68 #include "trace/tracing.hpp"
    69 #include "utilities/copy.hpp"
    70 #if defined AD_MD_HPP
    71 # include AD_MD_HPP
    72 #elif defined TARGET_ARCH_MODEL_x86_32
    73 # include "adfiles/ad_x86_32.hpp"
    74 #elif defined TARGET_ARCH_MODEL_x86_64
    75 # include "adfiles/ad_x86_64.hpp"
    76 #elif defined TARGET_ARCH_MODEL_sparc
    77 # include "adfiles/ad_sparc.hpp"
    78 #elif defined TARGET_ARCH_MODEL_zero
    79 # include "adfiles/ad_zero.hpp"
    80 #elif defined TARGET_ARCH_MODEL_ppc_64
    81 # include "adfiles/ad_ppc_64.hpp"
    82 #endif
    85 // -------------------- Compile::mach_constant_base_node -----------------------
    86 // Constant table base node singleton.
    87 MachConstantBaseNode* Compile::mach_constant_base_node() {
    88   if (_mach_constant_base_node == NULL) {
    89     _mach_constant_base_node = new (C) MachConstantBaseNode();
    90     _mach_constant_base_node->add_req(C->root());
    91   }
    92   return _mach_constant_base_node;
    93 }
    96 /// Support for intrinsics.
    98 // Return the index at which m must be inserted (or already exists).
    99 // The sort order is by the address of the ciMethod, with is_virtual as minor key.
   100 int Compile::intrinsic_insertion_index(ciMethod* m, bool is_virtual) {
   101 #ifdef ASSERT
   102   for (int i = 1; i < _intrinsics->length(); i++) {
   103     CallGenerator* cg1 = _intrinsics->at(i-1);
   104     CallGenerator* cg2 = _intrinsics->at(i);
   105     assert(cg1->method() != cg2->method()
   106            ? cg1->method()     < cg2->method()
   107            : cg1->is_virtual() < cg2->is_virtual(),
   108            "compiler intrinsics list must stay sorted");
   109   }
   110 #endif
   111   // Binary search sorted list, in decreasing intervals [lo, hi].
   112   int lo = 0, hi = _intrinsics->length()-1;
   113   while (lo <= hi) {
   114     int mid = (uint)(hi + lo) / 2;
   115     ciMethod* mid_m = _intrinsics->at(mid)->method();
   116     if (m < mid_m) {
   117       hi = mid-1;
   118     } else if (m > mid_m) {
   119       lo = mid+1;
   120     } else {
   121       // look at minor sort key
   122       bool mid_virt = _intrinsics->at(mid)->is_virtual();
   123       if (is_virtual < mid_virt) {
   124         hi = mid-1;
   125       } else if (is_virtual > mid_virt) {
   126         lo = mid+1;
   127       } else {
   128         return mid;  // exact match
   129       }
   130     }
   131   }
   132   return lo;  // inexact match
   133 }
   135 void Compile::register_intrinsic(CallGenerator* cg) {
   136   if (_intrinsics == NULL) {
   137     _intrinsics = new (comp_arena())GrowableArray<CallGenerator*>(comp_arena(), 60, 0, NULL);
   138   }
   139   // This code is stolen from ciObjectFactory::insert.
   140   // Really, GrowableArray should have methods for
   141   // insert_at, remove_at, and binary_search.
   142   int len = _intrinsics->length();
   143   int index = intrinsic_insertion_index(cg->method(), cg->is_virtual());
   144   if (index == len) {
   145     _intrinsics->append(cg);
   146   } else {
   147 #ifdef ASSERT
   148     CallGenerator* oldcg = _intrinsics->at(index);
   149     assert(oldcg->method() != cg->method() || oldcg->is_virtual() != cg->is_virtual(), "don't register twice");
   150 #endif
   151     _intrinsics->append(_intrinsics->at(len-1));
   152     int pos;
   153     for (pos = len-2; pos >= index; pos--) {
   154       _intrinsics->at_put(pos+1,_intrinsics->at(pos));
   155     }
   156     _intrinsics->at_put(index, cg);
   157   }
   158   assert(find_intrinsic(cg->method(), cg->is_virtual()) == cg, "registration worked");
   159 }
   161 CallGenerator* Compile::find_intrinsic(ciMethod* m, bool is_virtual) {
   162   assert(m->is_loaded(), "don't try this on unloaded methods");
   163   if (_intrinsics != NULL) {
   164     int index = intrinsic_insertion_index(m, is_virtual);
   165     if (index < _intrinsics->length()
   166         && _intrinsics->at(index)->method() == m
   167         && _intrinsics->at(index)->is_virtual() == is_virtual) {
   168       return _intrinsics->at(index);
   169     }
   170   }
   171   // Lazily create intrinsics for intrinsic IDs well-known in the runtime.
   172   if (m->intrinsic_id() != vmIntrinsics::_none &&
   173       m->intrinsic_id() <= vmIntrinsics::LAST_COMPILER_INLINE) {
   174     CallGenerator* cg = make_vm_intrinsic(m, is_virtual);
   175     if (cg != NULL) {
   176       // Save it for next time:
   177       register_intrinsic(cg);
   178       return cg;
   179     } else {
   180       gather_intrinsic_statistics(m->intrinsic_id(), is_virtual, _intrinsic_disabled);
   181     }
   182   }
   183   return NULL;
   184 }
   186 // Compile:: register_library_intrinsics and make_vm_intrinsic are defined
   187 // in library_call.cpp.
   190 #ifndef PRODUCT
   191 // statistics gathering...
   193 juint  Compile::_intrinsic_hist_count[vmIntrinsics::ID_LIMIT] = {0};
   194 jubyte Compile::_intrinsic_hist_flags[vmIntrinsics::ID_LIMIT] = {0};
   196 bool Compile::gather_intrinsic_statistics(vmIntrinsics::ID id, bool is_virtual, int flags) {
   197   assert(id > vmIntrinsics::_none && id < vmIntrinsics::ID_LIMIT, "oob");
   198   int oflags = _intrinsic_hist_flags[id];
   199   assert(flags != 0, "what happened?");
   200   if (is_virtual) {
   201     flags |= _intrinsic_virtual;
   202   }
   203   bool changed = (flags != oflags);
   204   if ((flags & _intrinsic_worked) != 0) {
   205     juint count = (_intrinsic_hist_count[id] += 1);
   206     if (count == 1) {
   207       changed = true;           // first time
   208     }
   209     // increment the overall count also:
   210     _intrinsic_hist_count[vmIntrinsics::_none] += 1;
   211   }
   212   if (changed) {
   213     if (((oflags ^ flags) & _intrinsic_virtual) != 0) {
   214       // Something changed about the intrinsic's virtuality.
   215       if ((flags & _intrinsic_virtual) != 0) {
   216         // This is the first use of this intrinsic as a virtual call.
   217         if (oflags != 0) {
   218           // We already saw it as a non-virtual, so note both cases.
   219           flags |= _intrinsic_both;
   220         }
   221       } else if ((oflags & _intrinsic_both) == 0) {
   222         // This is the first use of this intrinsic as a non-virtual
   223         flags |= _intrinsic_both;
   224       }
   225     }
   226     _intrinsic_hist_flags[id] = (jubyte) (oflags | flags);
   227   }
   228   // update the overall flags also:
   229   _intrinsic_hist_flags[vmIntrinsics::_none] |= (jubyte) flags;
   230   return changed;
   231 }
   233 static char* format_flags(int flags, char* buf) {
   234   buf[0] = 0;
   235   if ((flags & Compile::_intrinsic_worked) != 0)    strcat(buf, ",worked");
   236   if ((flags & Compile::_intrinsic_failed) != 0)    strcat(buf, ",failed");
   237   if ((flags & Compile::_intrinsic_disabled) != 0)  strcat(buf, ",disabled");
   238   if ((flags & Compile::_intrinsic_virtual) != 0)   strcat(buf, ",virtual");
   239   if ((flags & Compile::_intrinsic_both) != 0)      strcat(buf, ",nonvirtual");
   240   if (buf[0] == 0)  strcat(buf, ",");
   241   assert(buf[0] == ',', "must be");
   242   return &buf[1];
   243 }
   245 void Compile::print_intrinsic_statistics() {
   246   char flagsbuf[100];
   247   ttyLocker ttyl;
   248   if (xtty != NULL)  xtty->head("statistics type='intrinsic'");
   249   tty->print_cr("Compiler intrinsic usage:");
   250   juint total = _intrinsic_hist_count[vmIntrinsics::_none];
   251   if (total == 0)  total = 1;  // avoid div0 in case of no successes
   252   #define PRINT_STAT_LINE(name, c, f) \
   253     tty->print_cr("  %4d (%4.1f%%) %s (%s)", (int)(c), ((c) * 100.0) / total, name, f);
   254   for (int index = 1 + (int)vmIntrinsics::_none; index < (int)vmIntrinsics::ID_LIMIT; index++) {
   255     vmIntrinsics::ID id = (vmIntrinsics::ID) index;
   256     int   flags = _intrinsic_hist_flags[id];
   257     juint count = _intrinsic_hist_count[id];
   258     if ((flags | count) != 0) {
   259       PRINT_STAT_LINE(vmIntrinsics::name_at(id), count, format_flags(flags, flagsbuf));
   260     }
   261   }
   262   PRINT_STAT_LINE("total", total, format_flags(_intrinsic_hist_flags[vmIntrinsics::_none], flagsbuf));
   263   if (xtty != NULL)  xtty->tail("statistics");
   264 }
   266 void Compile::print_statistics() {
   267   { ttyLocker ttyl;
   268     if (xtty != NULL)  xtty->head("statistics type='opto'");
   269     Parse::print_statistics();
   270     PhaseCCP::print_statistics();
   271     PhaseRegAlloc::print_statistics();
   272     Scheduling::print_statistics();
   273     PhasePeephole::print_statistics();
   274     PhaseIdealLoop::print_statistics();
   275     if (xtty != NULL)  xtty->tail("statistics");
   276   }
   277   if (_intrinsic_hist_flags[vmIntrinsics::_none] != 0) {
   278     // put this under its own <statistics> element.
   279     print_intrinsic_statistics();
   280   }
   281 }
   282 #endif //PRODUCT
   284 // Support for bundling info
   285 Bundle* Compile::node_bundling(const Node *n) {
   286   assert(valid_bundle_info(n), "oob");
   287   return &_node_bundling_base[n->_idx];
   288 }
   290 bool Compile::valid_bundle_info(const Node *n) {
   291   return (_node_bundling_limit > n->_idx);
   292 }
   295 void Compile::gvn_replace_by(Node* n, Node* nn) {
   296   for (DUIterator_Last imin, i = n->last_outs(imin); i >= imin; ) {
   297     Node* use = n->last_out(i);
   298     bool is_in_table = initial_gvn()->hash_delete(use);
   299     uint uses_found = 0;
   300     for (uint j = 0; j < use->len(); j++) {
   301       if (use->in(j) == n) {
   302         if (j < use->req())
   303           use->set_req(j, nn);
   304         else
   305           use->set_prec(j, nn);
   306         uses_found++;
   307       }
   308     }
   309     if (is_in_table) {
   310       // reinsert into table
   311       initial_gvn()->hash_find_insert(use);
   312     }
   313     record_for_igvn(use);
   314     i -= uses_found;    // we deleted 1 or more copies of this edge
   315   }
   316 }
   319 static inline bool not_a_node(const Node* n) {
   320   if (n == NULL)                   return true;
   321   if (((intptr_t)n & 1) != 0)      return true;  // uninitialized, etc.
   322   if (*(address*)n == badAddress)  return true;  // kill by Node::destruct
   323   return false;
   324 }
   326 // Identify all nodes that are reachable from below, useful.
   327 // Use breadth-first pass that records state in a Unique_Node_List,
   328 // recursive traversal is slower.
   329 void Compile::identify_useful_nodes(Unique_Node_List &useful) {
   330   int estimated_worklist_size = live_nodes();
   331   useful.map( estimated_worklist_size, NULL );  // preallocate space
   333   // Initialize worklist
   334   if (root() != NULL)     { useful.push(root()); }
   335   // If 'top' is cached, declare it useful to preserve cached node
   336   if( cached_top_node() ) { useful.push(cached_top_node()); }
   338   // Push all useful nodes onto the list, breadthfirst
   339   for( uint next = 0; next < useful.size(); ++next ) {
   340     assert( next < unique(), "Unique useful nodes < total nodes");
   341     Node *n  = useful.at(next);
   342     uint max = n->len();
   343     for( uint i = 0; i < max; ++i ) {
   344       Node *m = n->in(i);
   345       if (not_a_node(m))  continue;
   346       useful.push(m);
   347     }
   348   }
   349 }
   351 // Update dead_node_list with any missing dead nodes using useful
   352 // list. Consider all non-useful nodes to be useless i.e., dead nodes.
   353 void Compile::update_dead_node_list(Unique_Node_List &useful) {
   354   uint max_idx = unique();
   355   VectorSet& useful_node_set = useful.member_set();
   357   for (uint node_idx = 0; node_idx < max_idx; node_idx++) {
   358     // If node with index node_idx is not in useful set,
   359     // mark it as dead in dead node list.
   360     if (! useful_node_set.test(node_idx) ) {
   361       record_dead_node(node_idx);
   362     }
   363   }
   364 }
   366 void Compile::remove_useless_late_inlines(GrowableArray<CallGenerator*>* inlines, Unique_Node_List &useful) {
   367   int shift = 0;
   368   for (int i = 0; i < inlines->length(); i++) {
   369     CallGenerator* cg = inlines->at(i);
   370     CallNode* call = cg->call_node();
   371     if (shift > 0) {
   372       inlines->at_put(i-shift, cg);
   373     }
   374     if (!useful.member(call)) {
   375       shift++;
   376     }
   377   }
   378   inlines->trunc_to(inlines->length()-shift);
   379 }
   381 // Disconnect all useless nodes by disconnecting those at the boundary.
   382 void Compile::remove_useless_nodes(Unique_Node_List &useful) {
   383   uint next = 0;
   384   while (next < useful.size()) {
   385     Node *n = useful.at(next++);
   386     if (n->is_SafePoint()) {
   387       // We're done with a parsing phase. Replaced nodes are not valid
   388       // beyond that point.
   389       n->as_SafePoint()->delete_replaced_nodes();
   390     }
   391     // Use raw traversal of out edges since this code removes out edges
   392     int max = n->outcnt();
   393     for (int j = 0; j < max; ++j) {
   394       Node* child = n->raw_out(j);
   395       if (! useful.member(child)) {
   396         assert(!child->is_top() || child != top(),
   397                "If top is cached in Compile object it is in useful list");
   398         // Only need to remove this out-edge to the useless node
   399         n->raw_del_out(j);
   400         --j;
   401         --max;
   402       }
   403     }
   404     if (n->outcnt() == 1 && n->has_special_unique_user()) {
   405       record_for_igvn(n->unique_out());
   406     }
   407   }
   408   // Remove useless macro and predicate opaq nodes
   409   for (int i = C->macro_count()-1; i >= 0; i--) {
   410     Node* n = C->macro_node(i);
   411     if (!useful.member(n)) {
   412       remove_macro_node(n);
   413     }
   414   }
   415   // Remove useless CastII nodes with range check dependency
   416   for (int i = range_check_cast_count() - 1; i >= 0; i--) {
   417     Node* cast = range_check_cast_node(i);
   418     if (!useful.member(cast)) {
   419       remove_range_check_cast(cast);
   420     }
   421   }
   422   // Remove useless expensive node
   423   for (int i = C->expensive_count()-1; i >= 0; i--) {
   424     Node* n = C->expensive_node(i);
   425     if (!useful.member(n)) {
   426       remove_expensive_node(n);
   427     }
   428   }
   429   // clean up the late inline lists
   430   remove_useless_late_inlines(&_string_late_inlines, useful);
   431   remove_useless_late_inlines(&_boxing_late_inlines, useful);
   432   remove_useless_late_inlines(&_late_inlines, useful);
   433   debug_only(verify_graph_edges(true/*check for no_dead_code*/);)
   434 }
   436 //------------------------------frame_size_in_words-----------------------------
   437 // frame_slots in units of words
   438 int Compile::frame_size_in_words() const {
   439   // shift is 0 in LP32 and 1 in LP64
   440   const int shift = (LogBytesPerWord - LogBytesPerInt);
   441   int words = _frame_slots >> shift;
   442   assert( words << shift == _frame_slots, "frame size must be properly aligned in LP64" );
   443   return words;
   444 }
   446 // To bang the stack of this compiled method we use the stack size
   447 // that the interpreter would need in case of a deoptimization. This
   448 // removes the need to bang the stack in the deoptimization blob which
   449 // in turn simplifies stack overflow handling.
   450 int Compile::bang_size_in_bytes() const {
   451   return MAX2(_interpreter_frame_size, frame_size_in_bytes());
   452 }
   454 // ============================================================================
   455 //------------------------------CompileWrapper---------------------------------
   456 class CompileWrapper : public StackObj {
   457   Compile *const _compile;
   458  public:
   459   CompileWrapper(Compile* compile);
   461   ~CompileWrapper();
   462 };
   464 CompileWrapper::CompileWrapper(Compile* compile) : _compile(compile) {
   465   // the Compile* pointer is stored in the current ciEnv:
   466   ciEnv* env = compile->env();
   467   assert(env == ciEnv::current(), "must already be a ciEnv active");
   468   assert(env->compiler_data() == NULL, "compile already active?");
   469   env->set_compiler_data(compile);
   470   assert(compile == Compile::current(), "sanity");
   472   compile->set_type_dict(NULL);
   473   compile->set_type_hwm(NULL);
   474   compile->set_type_last_size(0);
   475   compile->set_last_tf(NULL, NULL);
   476   compile->set_indexSet_arena(NULL);
   477   compile->set_indexSet_free_block_list(NULL);
   478   compile->init_type_arena();
   479   Type::Initialize(compile);
   480   _compile->set_scratch_buffer_blob(NULL);
   481   _compile->begin_method();
   482 }
   483 CompileWrapper::~CompileWrapper() {
   484   _compile->end_method();
   485   if (_compile->scratch_buffer_blob() != NULL)
   486     BufferBlob::free(_compile->scratch_buffer_blob());
   487   _compile->env()->set_compiler_data(NULL);
   488 }
   491 //----------------------------print_compile_messages---------------------------
   492 void Compile::print_compile_messages() {
   493 #ifndef PRODUCT
   494   // Check if recompiling
   495   if (_subsume_loads == false && PrintOpto) {
   496     // Recompiling without allowing machine instructions to subsume loads
   497     tty->print_cr("*********************************************************");
   498     tty->print_cr("** Bailout: Recompile without subsuming loads          **");
   499     tty->print_cr("*********************************************************");
   500   }
   501   if (_do_escape_analysis != DoEscapeAnalysis && PrintOpto) {
   502     // Recompiling without escape analysis
   503     tty->print_cr("*********************************************************");
   504     tty->print_cr("** Bailout: Recompile without escape analysis          **");
   505     tty->print_cr("*********************************************************");
   506   }
   507   if (_eliminate_boxing != EliminateAutoBox && PrintOpto) {
   508     // Recompiling without boxing elimination
   509     tty->print_cr("*********************************************************");
   510     tty->print_cr("** Bailout: Recompile without boxing elimination       **");
   511     tty->print_cr("*********************************************************");
   512   }
   513   if (env()->break_at_compile()) {
   514     // Open the debugger when compiling this method.
   515     tty->print("### Breaking when compiling: ");
   516     method()->print_short_name();
   517     tty->cr();
   518     BREAKPOINT;
   519   }
   521   if( PrintOpto ) {
   522     if (is_osr_compilation()) {
   523       tty->print("[OSR]%3d", _compile_id);
   524     } else {
   525       tty->print("%3d", _compile_id);
   526     }
   527   }
   528 #endif
   529 }
   532 //-----------------------init_scratch_buffer_blob------------------------------
   533 // Construct a temporary BufferBlob and cache it for this compile.
   534 void Compile::init_scratch_buffer_blob(int const_size) {
   535   // If there is already a scratch buffer blob allocated and the
   536   // constant section is big enough, use it.  Otherwise free the
   537   // current and allocate a new one.
   538   BufferBlob* blob = scratch_buffer_blob();
   539   if ((blob != NULL) && (const_size <= _scratch_const_size)) {
   540     // Use the current blob.
   541   } else {
   542     if (blob != NULL) {
   543       BufferBlob::free(blob);
   544     }
   546     ResourceMark rm;
   547     _scratch_const_size = const_size;
   548     int size = (MAX_inst_size + MAX_stubs_size + _scratch_const_size);
   549     blob = BufferBlob::create("Compile::scratch_buffer", size);
   550     // Record the buffer blob for next time.
   551     set_scratch_buffer_blob(blob);
   552     // Have we run out of code space?
   553     if (scratch_buffer_blob() == NULL) {
   554       // Let CompilerBroker disable further compilations.
   555       record_failure("Not enough space for scratch buffer in CodeCache");
   556       return;
   557     }
   558   }
   560   // Initialize the relocation buffers
   561   relocInfo* locs_buf = (relocInfo*) blob->content_end() - MAX_locs_size;
   562   set_scratch_locs_memory(locs_buf);
   563 }
   566 //-----------------------scratch_emit_size-------------------------------------
   567 // Helper function that computes size by emitting code
   568 uint Compile::scratch_emit_size(const Node* n) {
   569   // Start scratch_emit_size section.
   570   set_in_scratch_emit_size(true);
   572   // Emit into a trash buffer and count bytes emitted.
   573   // This is a pretty expensive way to compute a size,
   574   // but it works well enough if seldom used.
   575   // All common fixed-size instructions are given a size
   576   // method by the AD file.
   577   // Note that the scratch buffer blob and locs memory are
   578   // allocated at the beginning of the compile task, and
   579   // may be shared by several calls to scratch_emit_size.
   580   // The allocation of the scratch buffer blob is particularly
   581   // expensive, since it has to grab the code cache lock.
   582   BufferBlob* blob = this->scratch_buffer_blob();
   583   assert(blob != NULL, "Initialize BufferBlob at start");
   584   assert(blob->size() > MAX_inst_size, "sanity");
   585   relocInfo* locs_buf = scratch_locs_memory();
   586   address blob_begin = blob->content_begin();
   587   address blob_end   = (address)locs_buf;
   588   assert(blob->content_contains(blob_end), "sanity");
   589   CodeBuffer buf(blob_begin, blob_end - blob_begin);
   590   buf.initialize_consts_size(_scratch_const_size);
   591   buf.initialize_stubs_size(MAX_stubs_size);
   592   assert(locs_buf != NULL, "sanity");
   593   int lsize = MAX_locs_size / 3;
   594   buf.consts()->initialize_shared_locs(&locs_buf[lsize * 0], lsize);
   595   buf.insts()->initialize_shared_locs( &locs_buf[lsize * 1], lsize);
   596   buf.stubs()->initialize_shared_locs( &locs_buf[lsize * 2], lsize);
   598   // Do the emission.
   600   Label fakeL; // Fake label for branch instructions.
   601   Label*   saveL = NULL;
   602   uint save_bnum = 0;
   603   bool is_branch = n->is_MachBranch();
   604   if (is_branch) {
   605     MacroAssembler masm(&buf);
   606     masm.bind(fakeL);
   607     n->as_MachBranch()->save_label(&saveL, &save_bnum);
   608     n->as_MachBranch()->label_set(&fakeL, 0);
   609   }
   610   n->emit(buf, this->regalloc());
   611   if (is_branch) // Restore label.
   612     n->as_MachBranch()->label_set(saveL, save_bnum);
   614   // End scratch_emit_size section.
   615   set_in_scratch_emit_size(false);
   617   return buf.insts_size();
   618 }
   621 // ============================================================================
   622 //------------------------------Compile standard-------------------------------
   623 debug_only( int Compile::_debug_idx = 100000; )
   625 // Compile a method.  entry_bci is -1 for normal compilations and indicates
   626 // the continuation bci for on stack replacement.
   629 Compile::Compile( ciEnv* ci_env, C2Compiler* compiler, ciMethod* target, int osr_bci,
   630                   bool subsume_loads, bool do_escape_analysis, bool eliminate_boxing )
   631                 : Phase(Compiler),
   632                   _env(ci_env),
   633                   _log(ci_env->log()),
   634                   _compile_id(ci_env->compile_id()),
   635                   _save_argument_registers(false),
   636                   _stub_name(NULL),
   637                   _stub_function(NULL),
   638                   _stub_entry_point(NULL),
   639                   _method(target),
   640                   _entry_bci(osr_bci),
   641                   _initial_gvn(NULL),
   642                   _for_igvn(NULL),
   643                   _warm_calls(NULL),
   644                   _subsume_loads(subsume_loads),
   645                   _do_escape_analysis(do_escape_analysis),
   646                   _eliminate_boxing(eliminate_boxing),
   647                   _failure_reason(NULL),
   648                   _code_buffer("Compile::Fill_buffer"),
   649                   _orig_pc_slot(0),
   650                   _orig_pc_slot_offset_in_bytes(0),
   651                   _has_method_handle_invokes(false),
   652                   _mach_constant_base_node(NULL),
   653                   _node_bundling_limit(0),
   654                   _node_bundling_base(NULL),
   655                   _java_calls(0),
   656                   _inner_loops(0),
   657                   _scratch_const_size(-1),
   658                   _in_scratch_emit_size(false),
   659                   _dead_node_list(comp_arena()),
   660                   _dead_node_count(0),
   661 #ifndef PRODUCT
   662                   _trace_opto_output(TraceOptoOutput || method()->has_option("TraceOptoOutput")),
   663                   _in_dump_cnt(0),
   664                   _printer(IdealGraphPrinter::printer()),
   665 #endif
   666                   _congraph(NULL),
   667                   _comp_arena(mtCompiler),
   668                   _node_arena(mtCompiler),
   669                   _old_arena(mtCompiler),
   670                   _Compile_types(mtCompiler),
   671                   _replay_inline_data(NULL),
   672                   _late_inlines(comp_arena(), 2, 0, NULL),
   673                   _string_late_inlines(comp_arena(), 2, 0, NULL),
   674                   _boxing_late_inlines(comp_arena(), 2, 0, NULL),
   675                   _late_inlines_pos(0),
   676                   _number_of_mh_late_inlines(0),
   677                   _inlining_progress(false),
   678                   _inlining_incrementally(false),
   679                   _print_inlining_list(NULL),
   680                   _print_inlining_idx(0),
   681                   _interpreter_frame_size(0),
   682                   _max_node_limit(MaxNodeLimit) {
   683   C = this;
   685   CompileWrapper cw(this);
   686 #ifndef PRODUCT
   687   if (TimeCompiler2) {
   688     tty->print(" ");
   689     target->holder()->name()->print();
   690     tty->print(".");
   691     target->print_short_name();
   692     tty->print("  ");
   693   }
   694   TraceTime t1("Total compilation time", &_t_totalCompilation, TimeCompiler, TimeCompiler2);
   695   TraceTime t2(NULL, &_t_methodCompilation, TimeCompiler, false);
   696   bool print_opto_assembly = PrintOptoAssembly || _method->has_option("PrintOptoAssembly");
   697   if (!print_opto_assembly) {
   698     bool print_assembly = (PrintAssembly || _method->should_print_assembly());
   699     if (print_assembly && !Disassembler::can_decode()) {
   700       tty->print_cr("PrintAssembly request changed to PrintOptoAssembly");
   701       print_opto_assembly = true;
   702     }
   703   }
   704   set_print_assembly(print_opto_assembly);
   705   set_parsed_irreducible_loop(false);
   707   if (method()->has_option("ReplayInline")) {
   708     _replay_inline_data = ciReplay::load_inline_data(method(), entry_bci(), ci_env->comp_level());
   709   }
   710 #endif
   711   set_print_inlining(PrintInlining || method()->has_option("PrintInlining") NOT_PRODUCT( || PrintOptoInlining));
   712   set_print_intrinsics(PrintIntrinsics || method()->has_option("PrintIntrinsics"));
   713   set_has_irreducible_loop(true); // conservative until build_loop_tree() reset it
   715   if (ProfileTraps RTM_OPT_ONLY( || UseRTMLocking )) {
   716     // Make sure the method being compiled gets its own MDO,
   717     // so we can at least track the decompile_count().
   718     // Need MDO to record RTM code generation state.
   719     method()->ensure_method_data();
   720   }
   722   Init(::AliasLevel);
   725   print_compile_messages();
   727   _ilt = InlineTree::build_inline_tree_root();
   729   // Even if NO memory addresses are used, MergeMem nodes must have at least 1 slice
   730   assert(num_alias_types() >= AliasIdxRaw, "");
   732 #define MINIMUM_NODE_HASH  1023
   733   // Node list that Iterative GVN will start with
   734   Unique_Node_List for_igvn(comp_arena());
   735   set_for_igvn(&for_igvn);
   737   // GVN that will be run immediately on new nodes
   738   uint estimated_size = method()->code_size()*4+64;
   739   estimated_size = (estimated_size < MINIMUM_NODE_HASH ? MINIMUM_NODE_HASH : estimated_size);
   740   PhaseGVN gvn(node_arena(), estimated_size);
   741   set_initial_gvn(&gvn);
   743   if (print_inlining() || print_intrinsics()) {
   744     _print_inlining_list = new (comp_arena())GrowableArray<PrintInliningBuffer>(comp_arena(), 1, 1, PrintInliningBuffer());
   745   }
   746   { // Scope for timing the parser
   747     TracePhase t3("parse", &_t_parser, true);
   749     // Put top into the hash table ASAP.
   750     initial_gvn()->transform_no_reclaim(top());
   752     // Set up tf(), start(), and find a CallGenerator.
   753     CallGenerator* cg = NULL;
   754     if (is_osr_compilation()) {
   755       const TypeTuple *domain = StartOSRNode::osr_domain();
   756       const TypeTuple *range = TypeTuple::make_range(method()->signature());
   757       init_tf(TypeFunc::make(domain, range));
   758       StartNode* s = new (this) StartOSRNode(root(), domain);
   759       initial_gvn()->set_type_bottom(s);
   760       init_start(s);
   761       cg = CallGenerator::for_osr(method(), entry_bci());
   762     } else {
   763       // Normal case.
   764       init_tf(TypeFunc::make(method()));
   765       StartNode* s = new (this) StartNode(root(), tf()->domain());
   766       initial_gvn()->set_type_bottom(s);
   767       init_start(s);
   768       if (method()->intrinsic_id() == vmIntrinsics::_Reference_get && UseG1GC) {
   769         // With java.lang.ref.reference.get() we must go through the
   770         // intrinsic when G1 is enabled - even when get() is the root
   771         // method of the compile - so that, if necessary, the value in
   772         // the referent field of the reference object gets recorded by
   773         // the pre-barrier code.
   774         // Specifically, if G1 is enabled, the value in the referent
   775         // field is recorded by the G1 SATB pre barrier. This will
   776         // result in the referent being marked live and the reference
   777         // object removed from the list of discovered references during
   778         // reference processing.
   779         cg = find_intrinsic(method(), false);
   780       }
   781       if (cg == NULL) {
   782         float past_uses = method()->interpreter_invocation_count();
   783         float expected_uses = past_uses;
   784         cg = CallGenerator::for_inline(method(), expected_uses);
   785       }
   786     }
   787     if (failing())  return;
   788     if (cg == NULL) {
   789       record_method_not_compilable_all_tiers("cannot parse method");
   790       return;
   791     }
   792     JVMState* jvms = build_start_state(start(), tf());
   793     if ((jvms = cg->generate(jvms)) == NULL) {
   794       record_method_not_compilable("method parse failed");
   795       return;
   796     }
   797     GraphKit kit(jvms);
   799     if (!kit.stopped()) {
   800       // Accept return values, and transfer control we know not where.
   801       // This is done by a special, unique ReturnNode bound to root.
   802       return_values(kit.jvms());
   803     }
   805     if (kit.has_exceptions()) {
   806       // Any exceptions that escape from this call must be rethrown
   807       // to whatever caller is dynamically above us on the stack.
   808       // This is done by a special, unique RethrowNode bound to root.
   809       rethrow_exceptions(kit.transfer_exceptions_into_jvms());
   810     }
   812     assert(IncrementalInline || (_late_inlines.length() == 0 && !has_mh_late_inlines()), "incremental inlining is off");
   814     if (_late_inlines.length() == 0 && !has_mh_late_inlines() && !failing() && has_stringbuilder()) {
   815       inline_string_calls(true);
   816     }
   818     if (failing())  return;
   820     print_method(PHASE_BEFORE_REMOVEUSELESS, 3);
   822     // Remove clutter produced by parsing.
   823     if (!failing()) {
   824       ResourceMark rm;
   825       PhaseRemoveUseless pru(initial_gvn(), &for_igvn);
   826     }
   827   }
   829   // Note:  Large methods are capped off in do_one_bytecode().
   830   if (failing())  return;
   832   // After parsing, node notes are no longer automagic.
   833   // They must be propagated by register_new_node_with_optimizer(),
   834   // clone(), or the like.
   835   set_default_node_notes(NULL);
   837   for (;;) {
   838     int successes = Inline_Warm();
   839     if (failing())  return;
   840     if (successes == 0)  break;
   841   }
   843   // Drain the list.
   844   Finish_Warm();
   845 #ifndef PRODUCT
   846   if (_printer) {
   847     _printer->print_inlining(this);
   848   }
   849 #endif
   851   if (failing())  return;
   852   NOT_PRODUCT( verify_graph_edges(); )
   854   // Now optimize
   855   Optimize();
   856   if (failing())  return;
   857   NOT_PRODUCT( verify_graph_edges(); )
   859 #ifndef PRODUCT
   860   if (PrintIdeal) {
   861     ttyLocker ttyl;  // keep the following output all in one block
   862     // This output goes directly to the tty, not the compiler log.
   863     // To enable tools to match it up with the compilation activity,
   864     // be sure to tag this tty output with the compile ID.
   865     if (xtty != NULL) {
   866       xtty->head("ideal compile_id='%d'%s", compile_id(),
   867                  is_osr_compilation()    ? " compile_kind='osr'" :
   868                  "");
   869     }
   870     root()->dump(9999);
   871     if (xtty != NULL) {
   872       xtty->tail("ideal");
   873     }
   874   }
   875 #endif
   877   NOT_PRODUCT( verify_barriers(); )
   879   // Dump compilation data to replay it.
   880   if (method()->has_option("DumpReplay")) {
   881     env()->dump_replay_data(_compile_id);
   882   }
   883   if (method()->has_option("DumpInline") && (ilt() != NULL)) {
   884     env()->dump_inline_data(_compile_id);
   885   }
   887   // Now that we know the size of all the monitors we can add a fixed slot
   888   // for the original deopt pc.
   890   _orig_pc_slot =  fixed_slots();
   891   int next_slot = _orig_pc_slot + (sizeof(address) / VMRegImpl::stack_slot_size);
   892   set_fixed_slots(next_slot);
   894   // Compute when to use implicit null checks. Used by matching trap based
   895   // nodes and NullCheck optimization.
   896   set_allowed_deopt_reasons();
   898   // Now generate code
   899   Code_Gen();
   900   if (failing())  return;
   902   // Check if we want to skip execution of all compiled code.
   903   {
   904 #ifndef PRODUCT
   905     if (OptoNoExecute) {
   906       record_method_not_compilable("+OptoNoExecute");  // Flag as failed
   907       return;
   908     }
   909     TracePhase t2("install_code", &_t_registerMethod, TimeCompiler);
   910 #endif
   912     if (is_osr_compilation()) {
   913       _code_offsets.set_value(CodeOffsets::Verified_Entry, 0);
   914       _code_offsets.set_value(CodeOffsets::OSR_Entry, _first_block_size);
   915     } else {
   916       _code_offsets.set_value(CodeOffsets::Verified_Entry, _first_block_size);
   917       _code_offsets.set_value(CodeOffsets::OSR_Entry, 0);
   918     }
   920     env()->register_method(_method, _entry_bci,
   921                            &_code_offsets,
   922                            _orig_pc_slot_offset_in_bytes,
   923                            code_buffer(),
   924                            frame_size_in_words(), _oop_map_set,
   925                            &_handler_table, &_inc_table,
   926                            compiler,
   927                            env()->comp_level(),
   928                            has_unsafe_access(),
   929                            SharedRuntime::is_wide_vector(max_vector_size()),
   930                            rtm_state()
   931                            );
   933     if (log() != NULL) // Print code cache state into compiler log
   934       log()->code_cache_state();
   935   }
   936 }
   938 //------------------------------Compile----------------------------------------
   939 // Compile a runtime stub
   940 Compile::Compile( ciEnv* ci_env,
   941                   TypeFunc_generator generator,
   942                   address stub_function,
   943                   const char *stub_name,
   944                   int is_fancy_jump,
   945                   bool pass_tls,
   946                   bool save_arg_registers,
   947                   bool return_pc )
   948   : Phase(Compiler),
   949     _env(ci_env),
   950     _log(ci_env->log()),
   951     _compile_id(0),
   952     _save_argument_registers(save_arg_registers),
   953     _method(NULL),
   954     _stub_name(stub_name),
   955     _stub_function(stub_function),
   956     _stub_entry_point(NULL),
   957     _entry_bci(InvocationEntryBci),
   958     _initial_gvn(NULL),
   959     _for_igvn(NULL),
   960     _warm_calls(NULL),
   961     _orig_pc_slot(0),
   962     _orig_pc_slot_offset_in_bytes(0),
   963     _subsume_loads(true),
   964     _do_escape_analysis(false),
   965     _eliminate_boxing(false),
   966     _failure_reason(NULL),
   967     _code_buffer("Compile::Fill_buffer"),
   968     _has_method_handle_invokes(false),
   969     _mach_constant_base_node(NULL),
   970     _node_bundling_limit(0),
   971     _node_bundling_base(NULL),
   972     _java_calls(0),
   973     _inner_loops(0),
   974 #ifndef PRODUCT
   975     _trace_opto_output(TraceOptoOutput),
   976     _in_dump_cnt(0),
   977     _printer(NULL),
   978 #endif
   979     _comp_arena(mtCompiler),
   980     _node_arena(mtCompiler),
   981     _old_arena(mtCompiler),
   982     _Compile_types(mtCompiler),
   983     _dead_node_list(comp_arena()),
   984     _dead_node_count(0),
   985     _congraph(NULL),
   986     _replay_inline_data(NULL),
   987     _number_of_mh_late_inlines(0),
   988     _inlining_progress(false),
   989     _inlining_incrementally(false),
   990     _print_inlining_list(NULL),
   991     _print_inlining_idx(0),
   992     _allowed_reasons(0),
   993     _interpreter_frame_size(0),
   994     _max_node_limit(MaxNodeLimit) {
   995   C = this;
   997 #ifndef PRODUCT
   998   TraceTime t1(NULL, &_t_totalCompilation, TimeCompiler, false);
   999   TraceTime t2(NULL, &_t_stubCompilation, TimeCompiler, false);
  1000   set_print_assembly(PrintFrameConverterAssembly);
  1001   set_parsed_irreducible_loop(false);
  1002 #endif
  1003   set_has_irreducible_loop(false); // no loops
  1005   CompileWrapper cw(this);
  1006   Init(/*AliasLevel=*/ 0);
  1007   init_tf((*generator)());
  1010     // The following is a dummy for the sake of GraphKit::gen_stub
  1011     Unique_Node_List for_igvn(comp_arena());
  1012     set_for_igvn(&for_igvn);  // not used, but some GraphKit guys push on this
  1013     PhaseGVN gvn(Thread::current()->resource_area(),255);
  1014     set_initial_gvn(&gvn);    // not significant, but GraphKit guys use it pervasively
  1015     gvn.transform_no_reclaim(top());
  1017     GraphKit kit;
  1018     kit.gen_stub(stub_function, stub_name, is_fancy_jump, pass_tls, return_pc);
  1021   NOT_PRODUCT( verify_graph_edges(); )
  1022   Code_Gen();
  1023   if (failing())  return;
  1026   // Entry point will be accessed using compile->stub_entry_point();
  1027   if (code_buffer() == NULL) {
  1028     Matcher::soft_match_failure();
  1029   } else {
  1030     if (PrintAssembly && (WizardMode || Verbose))
  1031       tty->print_cr("### Stub::%s", stub_name);
  1033     if (!failing()) {
  1034       assert(_fixed_slots == 0, "no fixed slots used for runtime stubs");
  1036       // Make the NMethod
  1037       // For now we mark the frame as never safe for profile stackwalking
  1038       RuntimeStub *rs = RuntimeStub::new_runtime_stub(stub_name,
  1039                                                       code_buffer(),
  1040                                                       CodeOffsets::frame_never_safe,
  1041                                                       // _code_offsets.value(CodeOffsets::Frame_Complete),
  1042                                                       frame_size_in_words(),
  1043                                                       _oop_map_set,
  1044                                                       save_arg_registers);
  1045       assert(rs != NULL && rs->is_runtime_stub(), "sanity check");
  1047       _stub_entry_point = rs->entry_point();
  1052 //------------------------------Init-------------------------------------------
  1053 // Prepare for a single compilation
  1054 void Compile::Init(int aliaslevel) {
  1055   _unique  = 0;
  1056   _regalloc = NULL;
  1058   _tf      = NULL;  // filled in later
  1059   _top     = NULL;  // cached later
  1060   _matcher = NULL;  // filled in later
  1061   _cfg     = NULL;  // filled in later
  1063   set_24_bit_selection_and_mode(Use24BitFP, false);
  1065   _node_note_array = NULL;
  1066   _default_node_notes = NULL;
  1068   _immutable_memory = NULL; // filled in at first inquiry
  1070   // Globally visible Nodes
  1071   // First set TOP to NULL to give safe behavior during creation of RootNode
  1072   set_cached_top_node(NULL);
  1073   set_root(new (this) RootNode());
  1074   // Now that you have a Root to point to, create the real TOP
  1075   set_cached_top_node( new (this) ConNode(Type::TOP) );
  1076   set_recent_alloc(NULL, NULL);
  1078   // Create Debug Information Recorder to record scopes, oopmaps, etc.
  1079   env()->set_oop_recorder(new OopRecorder(env()->arena()));
  1080   env()->set_debug_info(new DebugInformationRecorder(env()->oop_recorder()));
  1081   env()->set_dependencies(new Dependencies(env()));
  1083   _fixed_slots = 0;
  1084   set_has_split_ifs(false);
  1085   set_has_loops(has_method() && method()->has_loops()); // first approximation
  1086   set_has_stringbuilder(false);
  1087   set_has_boxed_value(false);
  1088   _trap_can_recompile = false;  // no traps emitted yet
  1089   _major_progress = true; // start out assuming good things will happen
  1090   set_has_unsafe_access(false);
  1091   set_max_vector_size(0);
  1092   Copy::zero_to_bytes(_trap_hist, sizeof(_trap_hist));
  1093   set_decompile_count(0);
  1095   set_do_freq_based_layout(BlockLayoutByFrequency || method_has_option("BlockLayoutByFrequency"));
  1096   set_num_loop_opts(LoopOptsCount);
  1097   set_do_inlining(Inline);
  1098   set_max_inline_size(MaxInlineSize);
  1099   set_freq_inline_size(FreqInlineSize);
  1100   set_do_scheduling(OptoScheduling);
  1101   set_do_count_invocations(false);
  1102   set_do_method_data_update(false);
  1103   set_rtm_state(NoRTM); // No RTM lock eliding by default
  1104   method_has_option_value("MaxNodeLimit", _max_node_limit);
  1105 #if INCLUDE_RTM_OPT
  1106   if (UseRTMLocking && has_method() && (method()->method_data_or_null() != NULL)) {
  1107     int rtm_state = method()->method_data()->rtm_state();
  1108     if (method_has_option("NoRTMLockEliding") || ((rtm_state & NoRTM) != 0)) {
  1109       // Don't generate RTM lock eliding code.
  1110       set_rtm_state(NoRTM);
  1111     } else if (method_has_option("UseRTMLockEliding") || ((rtm_state & UseRTM) != 0) || !UseRTMDeopt) {
  1112       // Generate RTM lock eliding code without abort ratio calculation code.
  1113       set_rtm_state(UseRTM);
  1114     } else if (UseRTMDeopt) {
  1115       // Generate RTM lock eliding code and include abort ratio calculation
  1116       // code if UseRTMDeopt is on.
  1117       set_rtm_state(ProfileRTM);
  1120 #endif
  1121   if (debug_info()->recording_non_safepoints()) {
  1122     set_node_note_array(new(comp_arena()) GrowableArray<Node_Notes*>
  1123                         (comp_arena(), 8, 0, NULL));
  1124     set_default_node_notes(Node_Notes::make(this));
  1127   // // -- Initialize types before each compile --
  1128   // // Update cached type information
  1129   // if( _method && _method->constants() )
  1130   //   Type::update_loaded_types(_method, _method->constants());
  1132   // Init alias_type map.
  1133   if (!_do_escape_analysis && aliaslevel == 3)
  1134     aliaslevel = 2;  // No unique types without escape analysis
  1135   _AliasLevel = aliaslevel;
  1136   const int grow_ats = 16;
  1137   _max_alias_types = grow_ats;
  1138   _alias_types   = NEW_ARENA_ARRAY(comp_arena(), AliasType*, grow_ats);
  1139   AliasType* ats = NEW_ARENA_ARRAY(comp_arena(), AliasType,  grow_ats);
  1140   Copy::zero_to_bytes(ats, sizeof(AliasType)*grow_ats);
  1142     for (int i = 0; i < grow_ats; i++)  _alias_types[i] = &ats[i];
  1144   // Initialize the first few types.
  1145   _alias_types[AliasIdxTop]->Init(AliasIdxTop, NULL);
  1146   _alias_types[AliasIdxBot]->Init(AliasIdxBot, TypePtr::BOTTOM);
  1147   _alias_types[AliasIdxRaw]->Init(AliasIdxRaw, TypeRawPtr::BOTTOM);
  1148   _num_alias_types = AliasIdxRaw+1;
  1149   // Zero out the alias type cache.
  1150   Copy::zero_to_bytes(_alias_cache, sizeof(_alias_cache));
  1151   // A NULL adr_type hits in the cache right away.  Preload the right answer.
  1152   probe_alias_cache(NULL)->_index = AliasIdxTop;
  1154   _intrinsics = NULL;
  1155   _macro_nodes = new(comp_arena()) GrowableArray<Node*>(comp_arena(), 8,  0, NULL);
  1156   _predicate_opaqs = new(comp_arena()) GrowableArray<Node*>(comp_arena(), 8,  0, NULL);
  1157   _expensive_nodes = new(comp_arena()) GrowableArray<Node*>(comp_arena(), 8,  0, NULL);
  1158   _range_check_casts = new(comp_arena()) GrowableArray<Node*>(comp_arena(), 8,  0, NULL);
  1159   register_library_intrinsics();
  1162 //---------------------------init_start----------------------------------------
  1163 // Install the StartNode on this compile object.
  1164 void Compile::init_start(StartNode* s) {
  1165   if (failing())
  1166     return; // already failing
  1167   assert(s == start(), "");
  1170 StartNode* Compile::start() const {
  1171   assert(!failing(), "");
  1172   for (DUIterator_Fast imax, i = root()->fast_outs(imax); i < imax; i++) {
  1173     Node* start = root()->fast_out(i);
  1174     if( start->is_Start() )
  1175       return start->as_Start();
  1177   fatal("Did not find Start node!");
  1178   return NULL;
  1181 //-------------------------------immutable_memory-------------------------------------
  1182 // Access immutable memory
  1183 Node* Compile::immutable_memory() {
  1184   if (_immutable_memory != NULL) {
  1185     return _immutable_memory;
  1187   StartNode* s = start();
  1188   for (DUIterator_Fast imax, i = s->fast_outs(imax); true; i++) {
  1189     Node *p = s->fast_out(i);
  1190     if (p != s && p->as_Proj()->_con == TypeFunc::Memory) {
  1191       _immutable_memory = p;
  1192       return _immutable_memory;
  1195   ShouldNotReachHere();
  1196   return NULL;
  1199 //----------------------set_cached_top_node------------------------------------
  1200 // Install the cached top node, and make sure Node::is_top works correctly.
  1201 void Compile::set_cached_top_node(Node* tn) {
  1202   if (tn != NULL)  verify_top(tn);
  1203   Node* old_top = _top;
  1204   _top = tn;
  1205   // Calling Node::setup_is_top allows the nodes the chance to adjust
  1206   // their _out arrays.
  1207   if (_top != NULL)     _top->setup_is_top();
  1208   if (old_top != NULL)  old_top->setup_is_top();
  1209   assert(_top == NULL || top()->is_top(), "");
  1212 #ifdef ASSERT
  1213 uint Compile::count_live_nodes_by_graph_walk() {
  1214   Unique_Node_List useful(comp_arena());
  1215   // Get useful node list by walking the graph.
  1216   identify_useful_nodes(useful);
  1217   return useful.size();
  1220 void Compile::print_missing_nodes() {
  1222   // Return if CompileLog is NULL and PrintIdealNodeCount is false.
  1223   if ((_log == NULL) && (! PrintIdealNodeCount)) {
  1224     return;
  1227   // This is an expensive function. It is executed only when the user
  1228   // specifies VerifyIdealNodeCount option or otherwise knows the
  1229   // additional work that needs to be done to identify reachable nodes
  1230   // by walking the flow graph and find the missing ones using
  1231   // _dead_node_list.
  1233   Unique_Node_List useful(comp_arena());
  1234   // Get useful node list by walking the graph.
  1235   identify_useful_nodes(useful);
  1237   uint l_nodes = C->live_nodes();
  1238   uint l_nodes_by_walk = useful.size();
  1240   if (l_nodes != l_nodes_by_walk) {
  1241     if (_log != NULL) {
  1242       _log->begin_head("mismatched_nodes count='%d'", abs((int) (l_nodes - l_nodes_by_walk)));
  1243       _log->stamp();
  1244       _log->end_head();
  1246     VectorSet& useful_member_set = useful.member_set();
  1247     int last_idx = l_nodes_by_walk;
  1248     for (int i = 0; i < last_idx; i++) {
  1249       if (useful_member_set.test(i)) {
  1250         if (_dead_node_list.test(i)) {
  1251           if (_log != NULL) {
  1252             _log->elem("mismatched_node_info node_idx='%d' type='both live and dead'", i);
  1254           if (PrintIdealNodeCount) {
  1255             // Print the log message to tty
  1256               tty->print_cr("mismatched_node idx='%d' both live and dead'", i);
  1257               useful.at(i)->dump();
  1261       else if (! _dead_node_list.test(i)) {
  1262         if (_log != NULL) {
  1263           _log->elem("mismatched_node_info node_idx='%d' type='neither live nor dead'", i);
  1265         if (PrintIdealNodeCount) {
  1266           // Print the log message to tty
  1267           tty->print_cr("mismatched_node idx='%d' type='neither live nor dead'", i);
  1271     if (_log != NULL) {
  1272       _log->tail("mismatched_nodes");
  1276 #endif
  1278 #ifndef PRODUCT
  1279 void Compile::verify_top(Node* tn) const {
  1280   if (tn != NULL) {
  1281     assert(tn->is_Con(), "top node must be a constant");
  1282     assert(((ConNode*)tn)->type() == Type::TOP, "top node must have correct type");
  1283     assert(tn->in(0) != NULL, "must have live top node");
  1286 #endif
  1289 ///-------------------Managing Per-Node Debug & Profile Info-------------------
  1291 void Compile::grow_node_notes(GrowableArray<Node_Notes*>* arr, int grow_by) {
  1292   guarantee(arr != NULL, "");
  1293   int num_blocks = arr->length();
  1294   if (grow_by < num_blocks)  grow_by = num_blocks;
  1295   int num_notes = grow_by * _node_notes_block_size;
  1296   Node_Notes* notes = NEW_ARENA_ARRAY(node_arena(), Node_Notes, num_notes);
  1297   Copy::zero_to_bytes(notes, num_notes * sizeof(Node_Notes));
  1298   while (num_notes > 0) {
  1299     arr->append(notes);
  1300     notes     += _node_notes_block_size;
  1301     num_notes -= _node_notes_block_size;
  1303   assert(num_notes == 0, "exact multiple, please");
  1306 bool Compile::copy_node_notes_to(Node* dest, Node* source) {
  1307   if (source == NULL || dest == NULL)  return false;
  1309   if (dest->is_Con())
  1310     return false;               // Do not push debug info onto constants.
  1312 #ifdef ASSERT
  1313   // Leave a bread crumb trail pointing to the original node:
  1314   if (dest != NULL && dest != source && dest->debug_orig() == NULL) {
  1315     dest->set_debug_orig(source);
  1317 #endif
  1319   if (node_note_array() == NULL)
  1320     return false;               // Not collecting any notes now.
  1322   // This is a copy onto a pre-existing node, which may already have notes.
  1323   // If both nodes have notes, do not overwrite any pre-existing notes.
  1324   Node_Notes* source_notes = node_notes_at(source->_idx);
  1325   if (source_notes == NULL || source_notes->is_clear())  return false;
  1326   Node_Notes* dest_notes   = node_notes_at(dest->_idx);
  1327   if (dest_notes == NULL || dest_notes->is_clear()) {
  1328     return set_node_notes_at(dest->_idx, source_notes);
  1331   Node_Notes merged_notes = (*source_notes);
  1332   // The order of operations here ensures that dest notes will win...
  1333   merged_notes.update_from(dest_notes);
  1334   return set_node_notes_at(dest->_idx, &merged_notes);
  1338 //--------------------------allow_range_check_smearing-------------------------
  1339 // Gating condition for coalescing similar range checks.
  1340 // Sometimes we try 'speculatively' replacing a series of a range checks by a
  1341 // single covering check that is at least as strong as any of them.
  1342 // If the optimization succeeds, the simplified (strengthened) range check
  1343 // will always succeed.  If it fails, we will deopt, and then give up
  1344 // on the optimization.
  1345 bool Compile::allow_range_check_smearing() const {
  1346   // If this method has already thrown a range-check,
  1347   // assume it was because we already tried range smearing
  1348   // and it failed.
  1349   uint already_trapped = trap_count(Deoptimization::Reason_range_check);
  1350   return !already_trapped;
  1354 //------------------------------flatten_alias_type-----------------------------
  1355 const TypePtr *Compile::flatten_alias_type( const TypePtr *tj ) const {
  1356   int offset = tj->offset();
  1357   TypePtr::PTR ptr = tj->ptr();
  1359   // Known instance (scalarizable allocation) alias only with itself.
  1360   bool is_known_inst = tj->isa_oopptr() != NULL &&
  1361                        tj->is_oopptr()->is_known_instance();
  1363   // Process weird unsafe references.
  1364   if (offset == Type::OffsetBot && (tj->isa_instptr() /*|| tj->isa_klassptr()*/)) {
  1365     assert(InlineUnsafeOps, "indeterminate pointers come only from unsafe ops");
  1366     assert(!is_known_inst, "scalarizable allocation should not have unsafe references");
  1367     tj = TypeOopPtr::BOTTOM;
  1368     ptr = tj->ptr();
  1369     offset = tj->offset();
  1372   // Array pointers need some flattening
  1373   const TypeAryPtr *ta = tj->isa_aryptr();
  1374   if (ta && ta->is_stable()) {
  1375     // Erase stability property for alias analysis.
  1376     tj = ta = ta->cast_to_stable(false);
  1378   if( ta && is_known_inst ) {
  1379     if ( offset != Type::OffsetBot &&
  1380          offset > arrayOopDesc::length_offset_in_bytes() ) {
  1381       offset = Type::OffsetBot; // Flatten constant access into array body only
  1382       tj = ta = TypeAryPtr::make(ptr, ta->ary(), ta->klass(), true, offset, ta->instance_id());
  1384   } else if( ta && _AliasLevel >= 2 ) {
  1385     // For arrays indexed by constant indices, we flatten the alias
  1386     // space to include all of the array body.  Only the header, klass
  1387     // and array length can be accessed un-aliased.
  1388     if( offset != Type::OffsetBot ) {
  1389       if( ta->const_oop() ) { // MethodData* or Method*
  1390         offset = Type::OffsetBot;   // Flatten constant access into array body
  1391         tj = ta = TypeAryPtr::make(ptr,ta->const_oop(),ta->ary(),ta->klass(),false,offset);
  1392       } else if( offset == arrayOopDesc::length_offset_in_bytes() ) {
  1393         // range is OK as-is.
  1394         tj = ta = TypeAryPtr::RANGE;
  1395       } else if( offset == oopDesc::klass_offset_in_bytes() ) {
  1396         tj = TypeInstPtr::KLASS; // all klass loads look alike
  1397         ta = TypeAryPtr::RANGE; // generic ignored junk
  1398         ptr = TypePtr::BotPTR;
  1399       } else if( offset == oopDesc::mark_offset_in_bytes() ) {
  1400         tj = TypeInstPtr::MARK;
  1401         ta = TypeAryPtr::RANGE; // generic ignored junk
  1402         ptr = TypePtr::BotPTR;
  1403       } else {                  // Random constant offset into array body
  1404         offset = Type::OffsetBot;   // Flatten constant access into array body
  1405         tj = ta = TypeAryPtr::make(ptr,ta->ary(),ta->klass(),false,offset);
  1408     // Arrays of fixed size alias with arrays of unknown size.
  1409     if (ta->size() != TypeInt::POS) {
  1410       const TypeAry *tary = TypeAry::make(ta->elem(), TypeInt::POS);
  1411       tj = ta = TypeAryPtr::make(ptr,ta->const_oop(),tary,ta->klass(),false,offset);
  1413     // Arrays of known objects become arrays of unknown objects.
  1414     if (ta->elem()->isa_narrowoop() && ta->elem() != TypeNarrowOop::BOTTOM) {
  1415       const TypeAry *tary = TypeAry::make(TypeNarrowOop::BOTTOM, ta->size());
  1416       tj = ta = TypeAryPtr::make(ptr,ta->const_oop(),tary,NULL,false,offset);
  1418     if (ta->elem()->isa_oopptr() && ta->elem() != TypeInstPtr::BOTTOM) {
  1419       const TypeAry *tary = TypeAry::make(TypeInstPtr::BOTTOM, ta->size());
  1420       tj = ta = TypeAryPtr::make(ptr,ta->const_oop(),tary,NULL,false,offset);
  1422     // Arrays of bytes and of booleans both use 'bastore' and 'baload' so
  1423     // cannot be distinguished by bytecode alone.
  1424     if (ta->elem() == TypeInt::BOOL) {
  1425       const TypeAry *tary = TypeAry::make(TypeInt::BYTE, ta->size());
  1426       ciKlass* aklass = ciTypeArrayKlass::make(T_BYTE);
  1427       tj = ta = TypeAryPtr::make(ptr,ta->const_oop(),tary,aklass,false,offset);
  1429     // During the 2nd round of IterGVN, NotNull castings are removed.
  1430     // Make sure the Bottom and NotNull variants alias the same.
  1431     // Also, make sure exact and non-exact variants alias the same.
  1432     if (ptr == TypePtr::NotNull || ta->klass_is_exact() || ta->speculative() != NULL) {
  1433       tj = ta = TypeAryPtr::make(TypePtr::BotPTR,ta->ary(),ta->klass(),false,offset);
  1437   // Oop pointers need some flattening
  1438   const TypeInstPtr *to = tj->isa_instptr();
  1439   if( to && _AliasLevel >= 2 && to != TypeOopPtr::BOTTOM ) {
  1440     ciInstanceKlass *k = to->klass()->as_instance_klass();
  1441     if( ptr == TypePtr::Constant ) {
  1442       if (to->klass() != ciEnv::current()->Class_klass() ||
  1443           offset < k->size_helper() * wordSize) {
  1444         // No constant oop pointers (such as Strings); they alias with
  1445         // unknown strings.
  1446         assert(!is_known_inst, "not scalarizable allocation");
  1447         tj = to = TypeInstPtr::make(TypePtr::BotPTR,to->klass(),false,0,offset);
  1449     } else if( is_known_inst ) {
  1450       tj = to; // Keep NotNull and klass_is_exact for instance type
  1451     } else if( ptr == TypePtr::NotNull || to->klass_is_exact() ) {
  1452       // During the 2nd round of IterGVN, NotNull castings are removed.
  1453       // Make sure the Bottom and NotNull variants alias the same.
  1454       // Also, make sure exact and non-exact variants alias the same.
  1455       tj = to = TypeInstPtr::make(TypePtr::BotPTR,to->klass(),false,0,offset);
  1457     if (to->speculative() != NULL) {
  1458       tj = to = TypeInstPtr::make(to->ptr(),to->klass(),to->klass_is_exact(),to->const_oop(),to->offset(), to->instance_id());
  1460     // Canonicalize the holder of this field
  1461     if (offset >= 0 && offset < instanceOopDesc::base_offset_in_bytes()) {
  1462       // First handle header references such as a LoadKlassNode, even if the
  1463       // object's klass is unloaded at compile time (4965979).
  1464       if (!is_known_inst) { // Do it only for non-instance types
  1465         tj = to = TypeInstPtr::make(TypePtr::BotPTR, env()->Object_klass(), false, NULL, offset);
  1467     } else if (offset < 0 || offset >= k->size_helper() * wordSize) {
  1468       // Static fields are in the space above the normal instance
  1469       // fields in the java.lang.Class instance.
  1470       if (to->klass() != ciEnv::current()->Class_klass()) {
  1471         to = NULL;
  1472         tj = TypeOopPtr::BOTTOM;
  1473         offset = tj->offset();
  1475     } else {
  1476       ciInstanceKlass *canonical_holder = k->get_canonical_holder(offset);
  1477       if (!k->equals(canonical_holder) || tj->offset() != offset) {
  1478         if( is_known_inst ) {
  1479           tj = to = TypeInstPtr::make(to->ptr(), canonical_holder, true, NULL, offset, to->instance_id());
  1480         } else {
  1481           tj = to = TypeInstPtr::make(to->ptr(), canonical_holder, false, NULL, offset);
  1487   // Klass pointers to object array klasses need some flattening
  1488   const TypeKlassPtr *tk = tj->isa_klassptr();
  1489   if( tk ) {
  1490     // If we are referencing a field within a Klass, we need
  1491     // to assume the worst case of an Object.  Both exact and
  1492     // inexact types must flatten to the same alias class so
  1493     // use NotNull as the PTR.
  1494     if ( offset == Type::OffsetBot || (offset >= 0 && (size_t)offset < sizeof(Klass)) ) {
  1496       tj = tk = TypeKlassPtr::make(TypePtr::NotNull,
  1497                                    TypeKlassPtr::OBJECT->klass(),
  1498                                    offset);
  1501     ciKlass* klass = tk->klass();
  1502     if( klass->is_obj_array_klass() ) {
  1503       ciKlass* k = TypeAryPtr::OOPS->klass();
  1504       if( !k || !k->is_loaded() )                  // Only fails for some -Xcomp runs
  1505         k = TypeInstPtr::BOTTOM->klass();
  1506       tj = tk = TypeKlassPtr::make( TypePtr::NotNull, k, offset );
  1509     // Check for precise loads from the primary supertype array and force them
  1510     // to the supertype cache alias index.  Check for generic array loads from
  1511     // the primary supertype array and also force them to the supertype cache
  1512     // alias index.  Since the same load can reach both, we need to merge
  1513     // these 2 disparate memories into the same alias class.  Since the
  1514     // primary supertype array is read-only, there's no chance of confusion
  1515     // where we bypass an array load and an array store.
  1516     int primary_supers_offset = in_bytes(Klass::primary_supers_offset());
  1517     if (offset == Type::OffsetBot ||
  1518         (offset >= primary_supers_offset &&
  1519          offset < (int)(primary_supers_offset + Klass::primary_super_limit() * wordSize)) ||
  1520         offset == (int)in_bytes(Klass::secondary_super_cache_offset())) {
  1521       offset = in_bytes(Klass::secondary_super_cache_offset());
  1522       tj = tk = TypeKlassPtr::make( TypePtr::NotNull, tk->klass(), offset );
  1526   // Flatten all Raw pointers together.
  1527   if (tj->base() == Type::RawPtr)
  1528     tj = TypeRawPtr::BOTTOM;
  1530   if (tj->base() == Type::AnyPtr)
  1531     tj = TypePtr::BOTTOM;      // An error, which the caller must check for.
  1533   // Flatten all to bottom for now
  1534   switch( _AliasLevel ) {
  1535   case 0:
  1536     tj = TypePtr::BOTTOM;
  1537     break;
  1538   case 1:                       // Flatten to: oop, static, field or array
  1539     switch (tj->base()) {
  1540     //case Type::AryPtr: tj = TypeAryPtr::RANGE;    break;
  1541     case Type::RawPtr:   tj = TypeRawPtr::BOTTOM;   break;
  1542     case Type::AryPtr:   // do not distinguish arrays at all
  1543     case Type::InstPtr:  tj = TypeInstPtr::BOTTOM;  break;
  1544     case Type::KlassPtr: tj = TypeKlassPtr::OBJECT; break;
  1545     case Type::AnyPtr:   tj = TypePtr::BOTTOM;      break;  // caller checks it
  1546     default: ShouldNotReachHere();
  1548     break;
  1549   case 2:                       // No collapsing at level 2; keep all splits
  1550   case 3:                       // No collapsing at level 3; keep all splits
  1551     break;
  1552   default:
  1553     Unimplemented();
  1556   offset = tj->offset();
  1557   assert( offset != Type::OffsetTop, "Offset has fallen from constant" );
  1559   assert( (offset != Type::OffsetBot && tj->base() != Type::AryPtr) ||
  1560           (offset == Type::OffsetBot && tj->base() == Type::AryPtr) ||
  1561           (offset == Type::OffsetBot && tj == TypeOopPtr::BOTTOM) ||
  1562           (offset == Type::OffsetBot && tj == TypePtr::BOTTOM) ||
  1563           (offset == oopDesc::mark_offset_in_bytes() && tj->base() == Type::AryPtr) ||
  1564           (offset == oopDesc::klass_offset_in_bytes() && tj->base() == Type::AryPtr) ||
  1565           (offset == arrayOopDesc::length_offset_in_bytes() && tj->base() == Type::AryPtr)  ,
  1566           "For oops, klasses, raw offset must be constant; for arrays the offset is never known" );
  1567   assert( tj->ptr() != TypePtr::TopPTR &&
  1568           tj->ptr() != TypePtr::AnyNull &&
  1569           tj->ptr() != TypePtr::Null, "No imprecise addresses" );
  1570 //    assert( tj->ptr() != TypePtr::Constant ||
  1571 //            tj->base() == Type::RawPtr ||
  1572 //            tj->base() == Type::KlassPtr, "No constant oop addresses" );
  1574   return tj;
  1577 void Compile::AliasType::Init(int i, const TypePtr* at) {
  1578   _index = i;
  1579   _adr_type = at;
  1580   _field = NULL;
  1581   _element = NULL;
  1582   _is_rewritable = true; // default
  1583   const TypeOopPtr *atoop = (at != NULL) ? at->isa_oopptr() : NULL;
  1584   if (atoop != NULL && atoop->is_known_instance()) {
  1585     const TypeOopPtr *gt = atoop->cast_to_instance_id(TypeOopPtr::InstanceBot);
  1586     _general_index = Compile::current()->get_alias_index(gt);
  1587   } else {
  1588     _general_index = 0;
  1592 //---------------------------------print_on------------------------------------
  1593 #ifndef PRODUCT
  1594 void Compile::AliasType::print_on(outputStream* st) {
  1595   if (index() < 10)
  1596         st->print("@ <%d> ", index());
  1597   else  st->print("@ <%d>",  index());
  1598   st->print(is_rewritable() ? "   " : " RO");
  1599   int offset = adr_type()->offset();
  1600   if (offset == Type::OffsetBot)
  1601         st->print(" +any");
  1602   else  st->print(" +%-3d", offset);
  1603   st->print(" in ");
  1604   adr_type()->dump_on(st);
  1605   const TypeOopPtr* tjp = adr_type()->isa_oopptr();
  1606   if (field() != NULL && tjp) {
  1607     if (tjp->klass()  != field()->holder() ||
  1608         tjp->offset() != field()->offset_in_bytes()) {
  1609       st->print(" != ");
  1610       field()->print();
  1611       st->print(" ***");
  1616 void print_alias_types() {
  1617   Compile* C = Compile::current();
  1618   tty->print_cr("--- Alias types, AliasIdxBot .. %d", C->num_alias_types()-1);
  1619   for (int idx = Compile::AliasIdxBot; idx < C->num_alias_types(); idx++) {
  1620     C->alias_type(idx)->print_on(tty);
  1621     tty->cr();
  1624 #endif
  1627 //----------------------------probe_alias_cache--------------------------------
  1628 Compile::AliasCacheEntry* Compile::probe_alias_cache(const TypePtr* adr_type) {
  1629   intptr_t key = (intptr_t) adr_type;
  1630   key ^= key >> logAliasCacheSize;
  1631   return &_alias_cache[key & right_n_bits(logAliasCacheSize)];
  1635 //-----------------------------grow_alias_types--------------------------------
  1636 void Compile::grow_alias_types() {
  1637   const int old_ats  = _max_alias_types; // how many before?
  1638   const int new_ats  = old_ats;          // how many more?
  1639   const int grow_ats = old_ats+new_ats;  // how many now?
  1640   _max_alias_types = grow_ats;
  1641   _alias_types =  REALLOC_ARENA_ARRAY(comp_arena(), AliasType*, _alias_types, old_ats, grow_ats);
  1642   AliasType* ats =    NEW_ARENA_ARRAY(comp_arena(), AliasType, new_ats);
  1643   Copy::zero_to_bytes(ats, sizeof(AliasType)*new_ats);
  1644   for (int i = 0; i < new_ats; i++)  _alias_types[old_ats+i] = &ats[i];
  1648 //--------------------------------find_alias_type------------------------------
  1649 Compile::AliasType* Compile::find_alias_type(const TypePtr* adr_type, bool no_create, ciField* original_field) {
  1650   if (_AliasLevel == 0)
  1651     return alias_type(AliasIdxBot);
  1653   AliasCacheEntry* ace = probe_alias_cache(adr_type);
  1654   if (ace->_adr_type == adr_type) {
  1655     return alias_type(ace->_index);
  1658   // Handle special cases.
  1659   if (adr_type == NULL)             return alias_type(AliasIdxTop);
  1660   if (adr_type == TypePtr::BOTTOM)  return alias_type(AliasIdxBot);
  1662   // Do it the slow way.
  1663   const TypePtr* flat = flatten_alias_type(adr_type);
  1665 #ifdef ASSERT
  1666   assert(flat == flatten_alias_type(flat), "idempotent");
  1667   assert(flat != TypePtr::BOTTOM,     "cannot alias-analyze an untyped ptr");
  1668   if (flat->isa_oopptr() && !flat->isa_klassptr()) {
  1669     const TypeOopPtr* foop = flat->is_oopptr();
  1670     // Scalarizable allocations have exact klass always.
  1671     bool exact = !foop->klass_is_exact() || foop->is_known_instance();
  1672     const TypePtr* xoop = foop->cast_to_exactness(exact)->is_ptr();
  1673     assert(foop == flatten_alias_type(xoop), "exactness must not affect alias type");
  1675   assert(flat == flatten_alias_type(flat), "exact bit doesn't matter");
  1676 #endif
  1678   int idx = AliasIdxTop;
  1679   for (int i = 0; i < num_alias_types(); i++) {
  1680     if (alias_type(i)->adr_type() == flat) {
  1681       idx = i;
  1682       break;
  1686   if (idx == AliasIdxTop) {
  1687     if (no_create)  return NULL;
  1688     // Grow the array if necessary.
  1689     if (_num_alias_types == _max_alias_types)  grow_alias_types();
  1690     // Add a new alias type.
  1691     idx = _num_alias_types++;
  1692     _alias_types[idx]->Init(idx, flat);
  1693     if (flat == TypeInstPtr::KLASS)  alias_type(idx)->set_rewritable(false);
  1694     if (flat == TypeAryPtr::RANGE)   alias_type(idx)->set_rewritable(false);
  1695     if (flat->isa_instptr()) {
  1696       if (flat->offset() == java_lang_Class::klass_offset_in_bytes()
  1697           && flat->is_instptr()->klass() == env()->Class_klass())
  1698         alias_type(idx)->set_rewritable(false);
  1700     if (flat->isa_aryptr()) {
  1701 #ifdef ASSERT
  1702       const int header_size_min  = arrayOopDesc::base_offset_in_bytes(T_BYTE);
  1703       // (T_BYTE has the weakest alignment and size restrictions...)
  1704       assert(flat->offset() < header_size_min, "array body reference must be OffsetBot");
  1705 #endif
  1706       if (flat->offset() == TypePtr::OffsetBot) {
  1707         alias_type(idx)->set_element(flat->is_aryptr()->elem());
  1710     if (flat->isa_klassptr()) {
  1711       if (flat->offset() == in_bytes(Klass::super_check_offset_offset()))
  1712         alias_type(idx)->set_rewritable(false);
  1713       if (flat->offset() == in_bytes(Klass::modifier_flags_offset()))
  1714         alias_type(idx)->set_rewritable(false);
  1715       if (flat->offset() == in_bytes(Klass::access_flags_offset()))
  1716         alias_type(idx)->set_rewritable(false);
  1717       if (flat->offset() == in_bytes(Klass::java_mirror_offset()))
  1718         alias_type(idx)->set_rewritable(false);
  1720     // %%% (We would like to finalize JavaThread::threadObj_offset(),
  1721     // but the base pointer type is not distinctive enough to identify
  1722     // references into JavaThread.)
  1724     // Check for final fields.
  1725     const TypeInstPtr* tinst = flat->isa_instptr();
  1726     if (tinst && tinst->offset() >= instanceOopDesc::base_offset_in_bytes()) {
  1727       ciField* field;
  1728       if (tinst->const_oop() != NULL &&
  1729           tinst->klass() == ciEnv::current()->Class_klass() &&
  1730           tinst->offset() >= (tinst->klass()->as_instance_klass()->size_helper() * wordSize)) {
  1731         // static field
  1732         ciInstanceKlass* k = tinst->const_oop()->as_instance()->java_lang_Class_klass()->as_instance_klass();
  1733         field = k->get_field_by_offset(tinst->offset(), true);
  1734       } else {
  1735         ciInstanceKlass *k = tinst->klass()->as_instance_klass();
  1736         field = k->get_field_by_offset(tinst->offset(), false);
  1738       assert(field == NULL ||
  1739              original_field == NULL ||
  1740              (field->holder() == original_field->holder() &&
  1741               field->offset() == original_field->offset() &&
  1742               field->is_static() == original_field->is_static()), "wrong field?");
  1743       // Set field() and is_rewritable() attributes.
  1744       if (field != NULL)  alias_type(idx)->set_field(field);
  1748   // Fill the cache for next time.
  1749   ace->_adr_type = adr_type;
  1750   ace->_index    = idx;
  1751   assert(alias_type(adr_type) == alias_type(idx),  "type must be installed");
  1753   // Might as well try to fill the cache for the flattened version, too.
  1754   AliasCacheEntry* face = probe_alias_cache(flat);
  1755   if (face->_adr_type == NULL) {
  1756     face->_adr_type = flat;
  1757     face->_index    = idx;
  1758     assert(alias_type(flat) == alias_type(idx), "flat type must work too");
  1761   return alias_type(idx);
  1765 Compile::AliasType* Compile::alias_type(ciField* field) {
  1766   const TypeOopPtr* t;
  1767   if (field->is_static())
  1768     t = TypeInstPtr::make(field->holder()->java_mirror());
  1769   else
  1770     t = TypeOopPtr::make_from_klass_raw(field->holder());
  1771   AliasType* atp = alias_type(t->add_offset(field->offset_in_bytes()), field);
  1772   assert((field->is_final() || field->is_stable()) == !atp->is_rewritable(), "must get the rewritable bits correct");
  1773   return atp;
  1777 //------------------------------have_alias_type--------------------------------
  1778 bool Compile::have_alias_type(const TypePtr* adr_type) {
  1779   AliasCacheEntry* ace = probe_alias_cache(adr_type);
  1780   if (ace->_adr_type == adr_type) {
  1781     return true;
  1784   // Handle special cases.
  1785   if (adr_type == NULL)             return true;
  1786   if (adr_type == TypePtr::BOTTOM)  return true;
  1788   return find_alias_type(adr_type, true, NULL) != NULL;
  1791 //-----------------------------must_alias--------------------------------------
  1792 // True if all values of the given address type are in the given alias category.
  1793 bool Compile::must_alias(const TypePtr* adr_type, int alias_idx) {
  1794   if (alias_idx == AliasIdxBot)         return true;  // the universal category
  1795   if (adr_type == NULL)                 return true;  // NULL serves as TypePtr::TOP
  1796   if (alias_idx == AliasIdxTop)         return false; // the empty category
  1797   if (adr_type->base() == Type::AnyPtr) return false; // TypePtr::BOTTOM or its twins
  1799   // the only remaining possible overlap is identity
  1800   int adr_idx = get_alias_index(adr_type);
  1801   assert(adr_idx != AliasIdxBot && adr_idx != AliasIdxTop, "");
  1802   assert(adr_idx == alias_idx ||
  1803          (alias_type(alias_idx)->adr_type() != TypeOopPtr::BOTTOM
  1804           && adr_type                       != TypeOopPtr::BOTTOM),
  1805          "should not be testing for overlap with an unsafe pointer");
  1806   return adr_idx == alias_idx;
  1809 //------------------------------can_alias--------------------------------------
  1810 // True if any values of the given address type are in the given alias category.
  1811 bool Compile::can_alias(const TypePtr* adr_type, int alias_idx) {
  1812   if (alias_idx == AliasIdxTop)         return false; // the empty category
  1813   if (adr_type == NULL)                 return false; // NULL serves as TypePtr::TOP
  1814   if (alias_idx == AliasIdxBot)         return true;  // the universal category
  1815   if (adr_type->base() == Type::AnyPtr) return true;  // TypePtr::BOTTOM or its twins
  1817   // the only remaining possible overlap is identity
  1818   int adr_idx = get_alias_index(adr_type);
  1819   assert(adr_idx != AliasIdxBot && adr_idx != AliasIdxTop, "");
  1820   return adr_idx == alias_idx;
  1825 //---------------------------pop_warm_call-------------------------------------
  1826 WarmCallInfo* Compile::pop_warm_call() {
  1827   WarmCallInfo* wci = _warm_calls;
  1828   if (wci != NULL)  _warm_calls = wci->remove_from(wci);
  1829   return wci;
  1832 //----------------------------Inline_Warm--------------------------------------
  1833 int Compile::Inline_Warm() {
  1834   // If there is room, try to inline some more warm call sites.
  1835   // %%% Do a graph index compaction pass when we think we're out of space?
  1836   if (!InlineWarmCalls)  return 0;
  1838   int calls_made_hot = 0;
  1839   int room_to_grow   = NodeCountInliningCutoff - unique();
  1840   int amount_to_grow = MIN2(room_to_grow, (int)NodeCountInliningStep);
  1841   int amount_grown   = 0;
  1842   WarmCallInfo* call;
  1843   while (amount_to_grow > 0 && (call = pop_warm_call()) != NULL) {
  1844     int est_size = (int)call->size();
  1845     if (est_size > (room_to_grow - amount_grown)) {
  1846       // This one won't fit anyway.  Get rid of it.
  1847       call->make_cold();
  1848       continue;
  1850     call->make_hot();
  1851     calls_made_hot++;
  1852     amount_grown   += est_size;
  1853     amount_to_grow -= est_size;
  1856   if (calls_made_hot > 0)  set_major_progress();
  1857   return calls_made_hot;
  1861 //----------------------------Finish_Warm--------------------------------------
  1862 void Compile::Finish_Warm() {
  1863   if (!InlineWarmCalls)  return;
  1864   if (failing())  return;
  1865   if (warm_calls() == NULL)  return;
  1867   // Clean up loose ends, if we are out of space for inlining.
  1868   WarmCallInfo* call;
  1869   while ((call = pop_warm_call()) != NULL) {
  1870     call->make_cold();
  1874 //---------------------cleanup_loop_predicates-----------------------
  1875 // Remove the opaque nodes that protect the predicates so that all unused
  1876 // checks and uncommon_traps will be eliminated from the ideal graph
  1877 void Compile::cleanup_loop_predicates(PhaseIterGVN &igvn) {
  1878   if (predicate_count()==0) return;
  1879   for (int i = predicate_count(); i > 0; i--) {
  1880     Node * n = predicate_opaque1_node(i-1);
  1881     assert(n->Opcode() == Op_Opaque1, "must be");
  1882     igvn.replace_node(n, n->in(1));
  1884   assert(predicate_count()==0, "should be clean!");
  1887 void Compile::add_range_check_cast(Node* n) {
  1888   assert(n->isa_CastII()->has_range_check(), "CastII should have range check dependency");
  1889   assert(!_range_check_casts->contains(n), "duplicate entry in range check casts");
  1890   _range_check_casts->append(n);
  1893 // Remove all range check dependent CastIINodes.
  1894 void Compile::remove_range_check_casts(PhaseIterGVN &igvn) {
  1895   for (int i = range_check_cast_count(); i > 0; i--) {
  1896     Node* cast = range_check_cast_node(i-1);
  1897     assert(cast->isa_CastII()->has_range_check(), "CastII should have range check dependency");
  1898     igvn.replace_node(cast, cast->in(1));
  1900   assert(range_check_cast_count() == 0, "should be empty");
  1903 // StringOpts and late inlining of string methods
  1904 void Compile::inline_string_calls(bool parse_time) {
  1906     // remove useless nodes to make the usage analysis simpler
  1907     ResourceMark rm;
  1908     PhaseRemoveUseless pru(initial_gvn(), for_igvn());
  1912     ResourceMark rm;
  1913     print_method(PHASE_BEFORE_STRINGOPTS, 3);
  1914     PhaseStringOpts pso(initial_gvn(), for_igvn());
  1915     print_method(PHASE_AFTER_STRINGOPTS, 3);
  1918   // now inline anything that we skipped the first time around
  1919   if (!parse_time) {
  1920     _late_inlines_pos = _late_inlines.length();
  1923   while (_string_late_inlines.length() > 0) {
  1924     CallGenerator* cg = _string_late_inlines.pop();
  1925     cg->do_late_inline();
  1926     if (failing())  return;
  1928   _string_late_inlines.trunc_to(0);
  1931 // Late inlining of boxing methods
  1932 void Compile::inline_boxing_calls(PhaseIterGVN& igvn) {
  1933   if (_boxing_late_inlines.length() > 0) {
  1934     assert(has_boxed_value(), "inconsistent");
  1936     PhaseGVN* gvn = initial_gvn();
  1937     set_inlining_incrementally(true);
  1939     assert( igvn._worklist.size() == 0, "should be done with igvn" );
  1940     for_igvn()->clear();
  1941     gvn->replace_with(&igvn);
  1943     _late_inlines_pos = _late_inlines.length();
  1945     while (_boxing_late_inlines.length() > 0) {
  1946       CallGenerator* cg = _boxing_late_inlines.pop();
  1947       cg->do_late_inline();
  1948       if (failing())  return;
  1950     _boxing_late_inlines.trunc_to(0);
  1953       ResourceMark rm;
  1954       PhaseRemoveUseless pru(gvn, for_igvn());
  1957     igvn = PhaseIterGVN(gvn);
  1958     igvn.optimize();
  1960     set_inlining_progress(false);
  1961     set_inlining_incrementally(false);
  1965 void Compile::inline_incrementally_one(PhaseIterGVN& igvn) {
  1966   assert(IncrementalInline, "incremental inlining should be on");
  1967   PhaseGVN* gvn = initial_gvn();
  1969   set_inlining_progress(false);
  1970   for_igvn()->clear();
  1971   gvn->replace_with(&igvn);
  1973   int i = 0;
  1975   for (; i <_late_inlines.length() && !inlining_progress(); i++) {
  1976     CallGenerator* cg = _late_inlines.at(i);
  1977     _late_inlines_pos = i+1;
  1978     cg->do_late_inline();
  1979     if (failing())  return;
  1981   int j = 0;
  1982   for (; i < _late_inlines.length(); i++, j++) {
  1983     _late_inlines.at_put(j, _late_inlines.at(i));
  1985   _late_inlines.trunc_to(j);
  1988     ResourceMark rm;
  1989     PhaseRemoveUseless pru(gvn, for_igvn());
  1992   igvn = PhaseIterGVN(gvn);
  1995 // Perform incremental inlining until bound on number of live nodes is reached
  1996 void Compile::inline_incrementally(PhaseIterGVN& igvn) {
  1997   PhaseGVN* gvn = initial_gvn();
  1999   set_inlining_incrementally(true);
  2000   set_inlining_progress(true);
  2001   uint low_live_nodes = 0;
  2003   while(inlining_progress() && _late_inlines.length() > 0) {
  2005     if (live_nodes() > (uint)LiveNodeCountInliningCutoff) {
  2006       if (low_live_nodes < (uint)LiveNodeCountInliningCutoff * 8 / 10) {
  2007         // PhaseIdealLoop is expensive so we only try it once we are
  2008         // out of live nodes and we only try it again if the previous
  2009         // helped got the number of nodes down significantly
  2010         PhaseIdealLoop ideal_loop( igvn, false, true );
  2011         if (failing())  return;
  2012         low_live_nodes = live_nodes();
  2013         _major_progress = true;
  2016       if (live_nodes() > (uint)LiveNodeCountInliningCutoff) {
  2017         break;
  2021     inline_incrementally_one(igvn);
  2023     if (failing())  return;
  2025     igvn.optimize();
  2027     if (failing())  return;
  2030   assert( igvn._worklist.size() == 0, "should be done with igvn" );
  2032   if (_string_late_inlines.length() > 0) {
  2033     assert(has_stringbuilder(), "inconsistent");
  2034     for_igvn()->clear();
  2035     initial_gvn()->replace_with(&igvn);
  2037     inline_string_calls(false);
  2039     if (failing())  return;
  2042       ResourceMark rm;
  2043       PhaseRemoveUseless pru(initial_gvn(), for_igvn());
  2046     igvn = PhaseIterGVN(gvn);
  2048     igvn.optimize();
  2051   set_inlining_incrementally(false);
  2055 //------------------------------Optimize---------------------------------------
  2056 // Given a graph, optimize it.
  2057 void Compile::Optimize() {
  2058   TracePhase t1("optimizer", &_t_optimizer, true);
  2060 #ifndef PRODUCT
  2061   if (env()->break_at_compile()) {
  2062     BREAKPOINT;
  2065 #endif
  2067   ResourceMark rm;
  2068   int          loop_opts_cnt;
  2070   NOT_PRODUCT( verify_graph_edges(); )
  2072   print_method(PHASE_AFTER_PARSING);
  2075   // Iterative Global Value Numbering, including ideal transforms
  2076   // Initialize IterGVN with types and values from parse-time GVN
  2077   PhaseIterGVN igvn(initial_gvn());
  2079     NOT_PRODUCT( TracePhase t2("iterGVN", &_t_iterGVN, TimeCompiler); )
  2080     igvn.optimize();
  2083   print_method(PHASE_ITER_GVN1, 2);
  2085   if (failing())  return;
  2088     NOT_PRODUCT( TracePhase t2("incrementalInline", &_t_incrInline, TimeCompiler); )
  2089     inline_incrementally(igvn);
  2092   print_method(PHASE_INCREMENTAL_INLINE, 2);
  2094   if (failing())  return;
  2096   if (eliminate_boxing()) {
  2097     NOT_PRODUCT( TracePhase t2("incrementalInline", &_t_incrInline, TimeCompiler); )
  2098     // Inline valueOf() methods now.
  2099     inline_boxing_calls(igvn);
  2101     if (AlwaysIncrementalInline) {
  2102       inline_incrementally(igvn);
  2105     print_method(PHASE_INCREMENTAL_BOXING_INLINE, 2);
  2107     if (failing())  return;
  2110   // Remove the speculative part of types and clean up the graph from
  2111   // the extra CastPP nodes whose only purpose is to carry them. Do
  2112   // that early so that optimizations are not disrupted by the extra
  2113   // CastPP nodes.
  2114   remove_speculative_types(igvn);
  2116   // No more new expensive nodes will be added to the list from here
  2117   // so keep only the actual candidates for optimizations.
  2118   cleanup_expensive_nodes(igvn);
  2120   // Perform escape analysis
  2121   if (_do_escape_analysis && ConnectionGraph::has_candidates(this)) {
  2122     if (has_loops()) {
  2123       // Cleanup graph (remove dead nodes).
  2124       TracePhase t2("idealLoop", &_t_idealLoop, true);
  2125       PhaseIdealLoop ideal_loop( igvn, false, true );
  2126       if (major_progress()) print_method(PHASE_PHASEIDEAL_BEFORE_EA, 2);
  2127       if (failing())  return;
  2129     ConnectionGraph::do_analysis(this, &igvn);
  2131     if (failing())  return;
  2133     // Optimize out fields loads from scalar replaceable allocations.
  2134     igvn.optimize();
  2135     print_method(PHASE_ITER_GVN_AFTER_EA, 2);
  2137     if (failing())  return;
  2139     if (congraph() != NULL && macro_count() > 0) {
  2140       NOT_PRODUCT( TracePhase t2("macroEliminate", &_t_macroEliminate, TimeCompiler); )
  2141       PhaseMacroExpand mexp(igvn);
  2142       mexp.eliminate_macro_nodes();
  2143       igvn.set_delay_transform(false);
  2145       igvn.optimize();
  2146       print_method(PHASE_ITER_GVN_AFTER_ELIMINATION, 2);
  2148       if (failing())  return;
  2152   // Loop transforms on the ideal graph.  Range Check Elimination,
  2153   // peeling, unrolling, etc.
  2155   // Set loop opts counter
  2156   loop_opts_cnt = num_loop_opts();
  2157   if((loop_opts_cnt > 0) && (has_loops() || has_split_ifs())) {
  2159       TracePhase t2("idealLoop", &_t_idealLoop, true);
  2160       PhaseIdealLoop ideal_loop( igvn, true );
  2161       loop_opts_cnt--;
  2162       if (major_progress()) print_method(PHASE_PHASEIDEALLOOP1, 2);
  2163       if (failing())  return;
  2165     // Loop opts pass if partial peeling occurred in previous pass
  2166     if(PartialPeelLoop && major_progress() && (loop_opts_cnt > 0)) {
  2167       TracePhase t3("idealLoop", &_t_idealLoop, true);
  2168       PhaseIdealLoop ideal_loop( igvn, false );
  2169       loop_opts_cnt--;
  2170       if (major_progress()) print_method(PHASE_PHASEIDEALLOOP2, 2);
  2171       if (failing())  return;
  2173     // Loop opts pass for loop-unrolling before CCP
  2174     if(major_progress() && (loop_opts_cnt > 0)) {
  2175       TracePhase t4("idealLoop", &_t_idealLoop, true);
  2176       PhaseIdealLoop ideal_loop( igvn, false );
  2177       loop_opts_cnt--;
  2178       if (major_progress()) print_method(PHASE_PHASEIDEALLOOP3, 2);
  2180     if (!failing()) {
  2181       // Verify that last round of loop opts produced a valid graph
  2182       NOT_PRODUCT( TracePhase t2("idealLoopVerify", &_t_idealLoopVerify, TimeCompiler); )
  2183       PhaseIdealLoop::verify(igvn);
  2186   if (failing())  return;
  2188   // Conditional Constant Propagation;
  2189   PhaseCCP ccp( &igvn );
  2190   assert( true, "Break here to ccp.dump_nodes_and_types(_root,999,1)");
  2192     TracePhase t2("ccp", &_t_ccp, true);
  2193     ccp.do_transform();
  2195   print_method(PHASE_CPP1, 2);
  2197   assert( true, "Break here to ccp.dump_old2new_map()");
  2199   // Iterative Global Value Numbering, including ideal transforms
  2201     NOT_PRODUCT( TracePhase t2("iterGVN2", &_t_iterGVN2, TimeCompiler); )
  2202     igvn = ccp;
  2203     igvn.optimize();
  2206   print_method(PHASE_ITER_GVN2, 2);
  2208   if (failing())  return;
  2210   // Loop transforms on the ideal graph.  Range Check Elimination,
  2211   // peeling, unrolling, etc.
  2212   if(loop_opts_cnt > 0) {
  2213     debug_only( int cnt = 0; );
  2214     while(major_progress() && (loop_opts_cnt > 0)) {
  2215       TracePhase t2("idealLoop", &_t_idealLoop, true);
  2216       assert( cnt++ < 40, "infinite cycle in loop optimization" );
  2217       PhaseIdealLoop ideal_loop( igvn, true);
  2218       loop_opts_cnt--;
  2219       if (major_progress()) print_method(PHASE_PHASEIDEALLOOP_ITERATIONS, 2);
  2220       if (failing())  return;
  2225     // Verify that all previous optimizations produced a valid graph
  2226     // at least to this point, even if no loop optimizations were done.
  2227     NOT_PRODUCT( TracePhase t2("idealLoopVerify", &_t_idealLoopVerify, TimeCompiler); )
  2228     PhaseIdealLoop::verify(igvn);
  2231   if (range_check_cast_count() > 0) {
  2232     // No more loop optimizations. Remove all range check dependent CastIINodes.
  2233     C->remove_range_check_casts(igvn);
  2234     igvn.optimize();
  2238     NOT_PRODUCT( TracePhase t2("macroExpand", &_t_macroExpand, TimeCompiler); )
  2239     PhaseMacroExpand  mex(igvn);
  2240     if (mex.expand_macro_nodes()) {
  2241       assert(failing(), "must bail out w/ explicit message");
  2242       return;
  2246  } // (End scope of igvn; run destructor if necessary for asserts.)
  2248   dump_inlining();
  2249   // A method with only infinite loops has no edges entering loops from root
  2251     NOT_PRODUCT( TracePhase t2("graphReshape", &_t_graphReshaping, TimeCompiler); )
  2252     if (final_graph_reshaping()) {
  2253       assert(failing(), "must bail out w/ explicit message");
  2254       return;
  2258   print_method(PHASE_OPTIMIZE_FINISHED, 2);
  2262 //------------------------------Code_Gen---------------------------------------
  2263 // Given a graph, generate code for it
  2264 void Compile::Code_Gen() {
  2265   if (failing()) {
  2266     return;
  2269   // Perform instruction selection.  You might think we could reclaim Matcher
  2270   // memory PDQ, but actually the Matcher is used in generating spill code.
  2271   // Internals of the Matcher (including some VectorSets) must remain live
  2272   // for awhile - thus I cannot reclaim Matcher memory lest a VectorSet usage
  2273   // set a bit in reclaimed memory.
  2275   // In debug mode can dump m._nodes.dump() for mapping of ideal to machine
  2276   // nodes.  Mapping is only valid at the root of each matched subtree.
  2277   NOT_PRODUCT( verify_graph_edges(); )
  2279   Matcher matcher;
  2280   _matcher = &matcher;
  2282     TracePhase t2("matcher", &_t_matcher, true);
  2283     matcher.match();
  2285   // In debug mode can dump m._nodes.dump() for mapping of ideal to machine
  2286   // nodes.  Mapping is only valid at the root of each matched subtree.
  2287   NOT_PRODUCT( verify_graph_edges(); )
  2289   // If you have too many nodes, or if matching has failed, bail out
  2290   check_node_count(0, "out of nodes matching instructions");
  2291   if (failing()) {
  2292     return;
  2295   // Build a proper-looking CFG
  2296   PhaseCFG cfg(node_arena(), root(), matcher);
  2297   _cfg = &cfg;
  2299     NOT_PRODUCT( TracePhase t2("scheduler", &_t_scheduler, TimeCompiler); )
  2300     bool success = cfg.do_global_code_motion();
  2301     if (!success) {
  2302       return;
  2305     print_method(PHASE_GLOBAL_CODE_MOTION, 2);
  2306     NOT_PRODUCT( verify_graph_edges(); )
  2307     debug_only( cfg.verify(); )
  2310   PhaseChaitin regalloc(unique(), cfg, matcher);
  2311   _regalloc = &regalloc;
  2313     TracePhase t2("regalloc", &_t_registerAllocation, true);
  2314     // Perform register allocation.  After Chaitin, use-def chains are
  2315     // no longer accurate (at spill code) and so must be ignored.
  2316     // Node->LRG->reg mappings are still accurate.
  2317     _regalloc->Register_Allocate();
  2319     // Bail out if the allocator builds too many nodes
  2320     if (failing()) {
  2321       return;
  2325   // Prior to register allocation we kept empty basic blocks in case the
  2326   // the allocator needed a place to spill.  After register allocation we
  2327   // are not adding any new instructions.  If any basic block is empty, we
  2328   // can now safely remove it.
  2330     NOT_PRODUCT( TracePhase t2("blockOrdering", &_t_blockOrdering, TimeCompiler); )
  2331     cfg.remove_empty_blocks();
  2332     if (do_freq_based_layout()) {
  2333       PhaseBlockLayout layout(cfg);
  2334     } else {
  2335       cfg.set_loop_alignment();
  2337     cfg.fixup_flow();
  2340   // Apply peephole optimizations
  2341   if( OptoPeephole ) {
  2342     NOT_PRODUCT( TracePhase t2("peephole", &_t_peephole, TimeCompiler); )
  2343     PhasePeephole peep( _regalloc, cfg);
  2344     peep.do_transform();
  2347   // Do late expand if CPU requires this.
  2348   if (Matcher::require_postalloc_expand) {
  2349     NOT_PRODUCT(TracePhase t2c("postalloc_expand", &_t_postalloc_expand, true));
  2350     cfg.postalloc_expand(_regalloc);
  2353   // Convert Nodes to instruction bits in a buffer
  2355     // %%%% workspace merge brought two timers together for one job
  2356     TracePhase t2a("output", &_t_output, true);
  2357     NOT_PRODUCT( TraceTime t2b(NULL, &_t_codeGeneration, TimeCompiler, false); )
  2358     Output();
  2361   print_method(PHASE_FINAL_CODE);
  2363   // He's dead, Jim.
  2364   _cfg     = (PhaseCFG*)0xdeadbeef;
  2365   _regalloc = (PhaseChaitin*)0xdeadbeef;
  2369 //------------------------------dump_asm---------------------------------------
  2370 // Dump formatted assembly
  2371 #ifndef PRODUCT
  2372 void Compile::dump_asm(int *pcs, uint pc_limit) {
  2373   bool cut_short = false;
  2374   tty->print_cr("#");
  2375   tty->print("#  ");  _tf->dump();  tty->cr();
  2376   tty->print_cr("#");
  2378   // For all blocks
  2379   int pc = 0x0;                 // Program counter
  2380   char starts_bundle = ' ';
  2381   _regalloc->dump_frame();
  2383   Node *n = NULL;
  2384   for (uint i = 0; i < _cfg->number_of_blocks(); i++) {
  2385     if (VMThread::should_terminate()) {
  2386       cut_short = true;
  2387       break;
  2389     Block* block = _cfg->get_block(i);
  2390     if (block->is_connector() && !Verbose) {
  2391       continue;
  2393     n = block->head();
  2394     if (pcs && n->_idx < pc_limit) {
  2395       tty->print("%3.3x   ", pcs[n->_idx]);
  2396     } else {
  2397       tty->print("      ");
  2399     block->dump_head(_cfg);
  2400     if (block->is_connector()) {
  2401       tty->print_cr("        # Empty connector block");
  2402     } else if (block->num_preds() == 2 && block->pred(1)->is_CatchProj() && block->pred(1)->as_CatchProj()->_con == CatchProjNode::fall_through_index) {
  2403       tty->print_cr("        # Block is sole successor of call");
  2406     // For all instructions
  2407     Node *delay = NULL;
  2408     for (uint j = 0; j < block->number_of_nodes(); j++) {
  2409       if (VMThread::should_terminate()) {
  2410         cut_short = true;
  2411         break;
  2413       n = block->get_node(j);
  2414       if (valid_bundle_info(n)) {
  2415         Bundle* bundle = node_bundling(n);
  2416         if (bundle->used_in_unconditional_delay()) {
  2417           delay = n;
  2418           continue;
  2420         if (bundle->starts_bundle()) {
  2421           starts_bundle = '+';
  2425       if (WizardMode) {
  2426         n->dump();
  2429       if( !n->is_Region() &&    // Dont print in the Assembly
  2430           !n->is_Phi() &&       // a few noisely useless nodes
  2431           !n->is_Proj() &&
  2432           !n->is_MachTemp() &&
  2433           !n->is_SafePointScalarObject() &&
  2434           !n->is_Catch() &&     // Would be nice to print exception table targets
  2435           !n->is_MergeMem() &&  // Not very interesting
  2436           !n->is_top() &&       // Debug info table constants
  2437           !(n->is_Con() && !n->is_Mach())// Debug info table constants
  2438           ) {
  2439         if (pcs && n->_idx < pc_limit)
  2440           tty->print("%3.3x", pcs[n->_idx]);
  2441         else
  2442           tty->print("   ");
  2443         tty->print(" %c ", starts_bundle);
  2444         starts_bundle = ' ';
  2445         tty->print("\t");
  2446         n->format(_regalloc, tty);
  2447         tty->cr();
  2450       // If we have an instruction with a delay slot, and have seen a delay,
  2451       // then back up and print it
  2452       if (valid_bundle_info(n) && node_bundling(n)->use_unconditional_delay()) {
  2453         assert(delay != NULL, "no unconditional delay instruction");
  2454         if (WizardMode) delay->dump();
  2456         if (node_bundling(delay)->starts_bundle())
  2457           starts_bundle = '+';
  2458         if (pcs && n->_idx < pc_limit)
  2459           tty->print("%3.3x", pcs[n->_idx]);
  2460         else
  2461           tty->print("   ");
  2462         tty->print(" %c ", starts_bundle);
  2463         starts_bundle = ' ';
  2464         tty->print("\t");
  2465         delay->format(_regalloc, tty);
  2466         tty->cr();
  2467         delay = NULL;
  2470       // Dump the exception table as well
  2471       if( n->is_Catch() && (Verbose || WizardMode) ) {
  2472         // Print the exception table for this offset
  2473         _handler_table.print_subtable_for(pc);
  2477     if (pcs && n->_idx < pc_limit)
  2478       tty->print_cr("%3.3x", pcs[n->_idx]);
  2479     else
  2480       tty->cr();
  2482     assert(cut_short || delay == NULL, "no unconditional delay branch");
  2484   } // End of per-block dump
  2485   tty->cr();
  2487   if (cut_short)  tty->print_cr("*** disassembly is cut short ***");
  2489 #endif
  2491 //------------------------------Final_Reshape_Counts---------------------------
  2492 // This class defines counters to help identify when a method
  2493 // may/must be executed using hardware with only 24-bit precision.
  2494 struct Final_Reshape_Counts : public StackObj {
  2495   int  _call_count;             // count non-inlined 'common' calls
  2496   int  _float_count;            // count float ops requiring 24-bit precision
  2497   int  _double_count;           // count double ops requiring more precision
  2498   int  _java_call_count;        // count non-inlined 'java' calls
  2499   int  _inner_loop_count;       // count loops which need alignment
  2500   VectorSet _visited;           // Visitation flags
  2501   Node_List _tests;             // Set of IfNodes & PCTableNodes
  2503   Final_Reshape_Counts() :
  2504     _call_count(0), _float_count(0), _double_count(0),
  2505     _java_call_count(0), _inner_loop_count(0),
  2506     _visited( Thread::current()->resource_area() ) { }
  2508   void inc_call_count  () { _call_count  ++; }
  2509   void inc_float_count () { _float_count ++; }
  2510   void inc_double_count() { _double_count++; }
  2511   void inc_java_call_count() { _java_call_count++; }
  2512   void inc_inner_loop_count() { _inner_loop_count++; }
  2514   int  get_call_count  () const { return _call_count  ; }
  2515   int  get_float_count () const { return _float_count ; }
  2516   int  get_double_count() const { return _double_count; }
  2517   int  get_java_call_count() const { return _java_call_count; }
  2518   int  get_inner_loop_count() const { return _inner_loop_count; }
  2519 };
  2521 #ifdef ASSERT
  2522 static bool oop_offset_is_sane(const TypeInstPtr* tp) {
  2523   ciInstanceKlass *k = tp->klass()->as_instance_klass();
  2524   // Make sure the offset goes inside the instance layout.
  2525   return k->contains_field_offset(tp->offset());
  2526   // Note that OffsetBot and OffsetTop are very negative.
  2528 #endif
  2530 // Eliminate trivially redundant StoreCMs and accumulate their
  2531 // precedence edges.
  2532 void Compile::eliminate_redundant_card_marks(Node* n) {
  2533   assert(n->Opcode() == Op_StoreCM, "expected StoreCM");
  2534   if (n->in(MemNode::Address)->outcnt() > 1) {
  2535     // There are multiple users of the same address so it might be
  2536     // possible to eliminate some of the StoreCMs
  2537     Node* mem = n->in(MemNode::Memory);
  2538     Node* adr = n->in(MemNode::Address);
  2539     Node* val = n->in(MemNode::ValueIn);
  2540     Node* prev = n;
  2541     bool done = false;
  2542     // Walk the chain of StoreCMs eliminating ones that match.  As
  2543     // long as it's a chain of single users then the optimization is
  2544     // safe.  Eliminating partially redundant StoreCMs would require
  2545     // cloning copies down the other paths.
  2546     while (mem->Opcode() == Op_StoreCM && mem->outcnt() == 1 && !done) {
  2547       if (adr == mem->in(MemNode::Address) &&
  2548           val == mem->in(MemNode::ValueIn)) {
  2549         // redundant StoreCM
  2550         if (mem->req() > MemNode::OopStore) {
  2551           // Hasn't been processed by this code yet.
  2552           n->add_prec(mem->in(MemNode::OopStore));
  2553         } else {
  2554           // Already converted to precedence edge
  2555           for (uint i = mem->req(); i < mem->len(); i++) {
  2556             // Accumulate any precedence edges
  2557             if (mem->in(i) != NULL) {
  2558               n->add_prec(mem->in(i));
  2561           // Everything above this point has been processed.
  2562           done = true;
  2564         // Eliminate the previous StoreCM
  2565         prev->set_req(MemNode::Memory, mem->in(MemNode::Memory));
  2566         assert(mem->outcnt() == 0, "should be dead");
  2567         mem->disconnect_inputs(NULL, this);
  2568       } else {
  2569         prev = mem;
  2571       mem = prev->in(MemNode::Memory);
  2576 //------------------------------final_graph_reshaping_impl----------------------
  2577 // Implement items 1-5 from final_graph_reshaping below.
  2578 void Compile::final_graph_reshaping_impl( Node *n, Final_Reshape_Counts &frc) {
  2580   if ( n->outcnt() == 0 ) return; // dead node
  2581   uint nop = n->Opcode();
  2583   // Check for 2-input instruction with "last use" on right input.
  2584   // Swap to left input.  Implements item (2).
  2585   if( n->req() == 3 &&          // two-input instruction
  2586       n->in(1)->outcnt() > 1 && // left use is NOT a last use
  2587       (!n->in(1)->is_Phi() || n->in(1)->in(2) != n) && // it is not data loop
  2588       n->in(2)->outcnt() == 1 &&// right use IS a last use
  2589       !n->in(2)->is_Con() ) {   // right use is not a constant
  2590     // Check for commutative opcode
  2591     switch( nop ) {
  2592     case Op_AddI:  case Op_AddF:  case Op_AddD:  case Op_AddL:
  2593     case Op_MaxI:  case Op_MinI:
  2594     case Op_MulI:  case Op_MulF:  case Op_MulD:  case Op_MulL:
  2595     case Op_AndL:  case Op_XorL:  case Op_OrL:
  2596     case Op_AndI:  case Op_XorI:  case Op_OrI: {
  2597       // Move "last use" input to left by swapping inputs
  2598       n->swap_edges(1, 2);
  2599       break;
  2601     default:
  2602       break;
  2606 #ifdef ASSERT
  2607   if( n->is_Mem() ) {
  2608     int alias_idx = get_alias_index(n->as_Mem()->adr_type());
  2609     assert( n->in(0) != NULL || alias_idx != Compile::AliasIdxRaw ||
  2610             // oop will be recorded in oop map if load crosses safepoint
  2611             n->is_Load() && (n->as_Load()->bottom_type()->isa_oopptr() ||
  2612                              LoadNode::is_immutable_value(n->in(MemNode::Address))),
  2613             "raw memory operations should have control edge");
  2615 #endif
  2616   // Count FPU ops and common calls, implements item (3)
  2617   switch( nop ) {
  2618   // Count all float operations that may use FPU
  2619   case Op_AddF:
  2620   case Op_SubF:
  2621   case Op_MulF:
  2622   case Op_DivF:
  2623   case Op_NegF:
  2624   case Op_ModF:
  2625   case Op_ConvI2F:
  2626   case Op_ConF:
  2627   case Op_CmpF:
  2628   case Op_CmpF3:
  2629   // case Op_ConvL2F: // longs are split into 32-bit halves
  2630     frc.inc_float_count();
  2631     break;
  2633   case Op_ConvF2D:
  2634   case Op_ConvD2F:
  2635     frc.inc_float_count();
  2636     frc.inc_double_count();
  2637     break;
  2639   // Count all double operations that may use FPU
  2640   case Op_AddD:
  2641   case Op_SubD:
  2642   case Op_MulD:
  2643   case Op_DivD:
  2644   case Op_NegD:
  2645   case Op_ModD:
  2646   case Op_ConvI2D:
  2647   case Op_ConvD2I:
  2648   // case Op_ConvL2D: // handled by leaf call
  2649   // case Op_ConvD2L: // handled by leaf call
  2650   case Op_ConD:
  2651   case Op_CmpD:
  2652   case Op_CmpD3:
  2653     frc.inc_double_count();
  2654     break;
  2655   case Op_Opaque1:              // Remove Opaque Nodes before matching
  2656   case Op_Opaque2:              // Remove Opaque Nodes before matching
  2657   case Op_Opaque3:
  2658     n->subsume_by(n->in(1), this);
  2659     break;
  2660   case Op_CallStaticJava:
  2661   case Op_CallJava:
  2662   case Op_CallDynamicJava:
  2663     frc.inc_java_call_count(); // Count java call site;
  2664   case Op_CallRuntime:
  2665   case Op_CallLeaf:
  2666   case Op_CallLeafNoFP: {
  2667     assert( n->is_Call(), "" );
  2668     CallNode *call = n->as_Call();
  2669     // Count call sites where the FP mode bit would have to be flipped.
  2670     // Do not count uncommon runtime calls:
  2671     // uncommon_trap, _complete_monitor_locking, _complete_monitor_unlocking,
  2672     // _new_Java, _new_typeArray, _new_objArray, _rethrow_Java, ...
  2673     if( !call->is_CallStaticJava() || !call->as_CallStaticJava()->_name ) {
  2674       frc.inc_call_count();   // Count the call site
  2675     } else {                  // See if uncommon argument is shared
  2676       Node *n = call->in(TypeFunc::Parms);
  2677       int nop = n->Opcode();
  2678       // Clone shared simple arguments to uncommon calls, item (1).
  2679       if( n->outcnt() > 1 &&
  2680           !n->is_Proj() &&
  2681           nop != Op_CreateEx &&
  2682           nop != Op_CheckCastPP &&
  2683           nop != Op_DecodeN &&
  2684           nop != Op_DecodeNKlass &&
  2685           !n->is_Mem() ) {
  2686         Node *x = n->clone();
  2687         call->set_req( TypeFunc::Parms, x );
  2690     break;
  2693   case Op_StoreD:
  2694   case Op_LoadD:
  2695   case Op_LoadD_unaligned:
  2696     frc.inc_double_count();
  2697     goto handle_mem;
  2698   case Op_StoreF:
  2699   case Op_LoadF:
  2700     frc.inc_float_count();
  2701     goto handle_mem;
  2703   case Op_StoreCM:
  2705       // Convert OopStore dependence into precedence edge
  2706       Node* prec = n->in(MemNode::OopStore);
  2707       n->del_req(MemNode::OopStore);
  2708       n->add_prec(prec);
  2709       eliminate_redundant_card_marks(n);
  2712     // fall through
  2714   case Op_StoreB:
  2715   case Op_StoreC:
  2716   case Op_StorePConditional:
  2717   case Op_StoreI:
  2718   case Op_StoreL:
  2719   case Op_StoreIConditional:
  2720   case Op_StoreLConditional:
  2721   case Op_CompareAndSwapI:
  2722   case Op_CompareAndSwapL:
  2723   case Op_CompareAndSwapP:
  2724   case Op_CompareAndSwapN:
  2725   case Op_GetAndAddI:
  2726   case Op_GetAndAddL:
  2727   case Op_GetAndSetI:
  2728   case Op_GetAndSetL:
  2729   case Op_GetAndSetP:
  2730   case Op_GetAndSetN:
  2731   case Op_StoreP:
  2732   case Op_StoreN:
  2733   case Op_StoreNKlass:
  2734   case Op_LoadB:
  2735   case Op_LoadUB:
  2736   case Op_LoadUS:
  2737   case Op_LoadI:
  2738   case Op_LoadKlass:
  2739   case Op_LoadNKlass:
  2740   case Op_LoadL:
  2741   case Op_LoadL_unaligned:
  2742   case Op_LoadPLocked:
  2743   case Op_LoadP:
  2744   case Op_LoadN:
  2745   case Op_LoadRange:
  2746   case Op_LoadS: {
  2747   handle_mem:
  2748 #ifdef ASSERT
  2749     if( VerifyOptoOopOffsets ) {
  2750       assert( n->is_Mem(), "" );
  2751       MemNode *mem  = (MemNode*)n;
  2752       // Check to see if address types have grounded out somehow.
  2753       const TypeInstPtr *tp = mem->in(MemNode::Address)->bottom_type()->isa_instptr();
  2754       assert( !tp || oop_offset_is_sane(tp), "" );
  2756 #endif
  2757     break;
  2760   case Op_AddP: {               // Assert sane base pointers
  2761     Node *addp = n->in(AddPNode::Address);
  2762     assert( !addp->is_AddP() ||
  2763             addp->in(AddPNode::Base)->is_top() || // Top OK for allocation
  2764             addp->in(AddPNode::Base) == n->in(AddPNode::Base),
  2765             "Base pointers must match" );
  2766 #ifdef _LP64
  2767     if ((UseCompressedOops || UseCompressedClassPointers) &&
  2768         addp->Opcode() == Op_ConP &&
  2769         addp == n->in(AddPNode::Base) &&
  2770         n->in(AddPNode::Offset)->is_Con()) {
  2771       // Use addressing with narrow klass to load with offset on x86.
  2772       // On sparc loading 32-bits constant and decoding it have less
  2773       // instructions (4) then load 64-bits constant (7).
  2774       // Do this transformation here since IGVN will convert ConN back to ConP.
  2775       const Type* t = addp->bottom_type();
  2776       if (t->isa_oopptr() || t->isa_klassptr()) {
  2777         Node* nn = NULL;
  2779         int op = t->isa_oopptr() ? Op_ConN : Op_ConNKlass;
  2781         // Look for existing ConN node of the same exact type.
  2782         Node* r  = root();
  2783         uint cnt = r->outcnt();
  2784         for (uint i = 0; i < cnt; i++) {
  2785           Node* m = r->raw_out(i);
  2786           if (m!= NULL && m->Opcode() == op &&
  2787               m->bottom_type()->make_ptr() == t) {
  2788             nn = m;
  2789             break;
  2792         if (nn != NULL) {
  2793           // Decode a narrow oop to match address
  2794           // [R12 + narrow_oop_reg<<3 + offset]
  2795           if (t->isa_oopptr()) {
  2796             nn = new (this) DecodeNNode(nn, t);
  2797           } else {
  2798             nn = new (this) DecodeNKlassNode(nn, t);
  2800           n->set_req(AddPNode::Base, nn);
  2801           n->set_req(AddPNode::Address, nn);
  2802           if (addp->outcnt() == 0) {
  2803             addp->disconnect_inputs(NULL, this);
  2808 #endif
  2809     break;
  2812 #ifdef _LP64
  2813   case Op_CastPP:
  2814     if (n->in(1)->is_DecodeN() && Matcher::gen_narrow_oop_implicit_null_checks()) {
  2815       Node* in1 = n->in(1);
  2816       const Type* t = n->bottom_type();
  2817       Node* new_in1 = in1->clone();
  2818       new_in1->as_DecodeN()->set_type(t);
  2820       if (!Matcher::narrow_oop_use_complex_address()) {
  2821         //
  2822         // x86, ARM and friends can handle 2 adds in addressing mode
  2823         // and Matcher can fold a DecodeN node into address by using
  2824         // a narrow oop directly and do implicit NULL check in address:
  2825         //
  2826         // [R12 + narrow_oop_reg<<3 + offset]
  2827         // NullCheck narrow_oop_reg
  2828         //
  2829         // On other platforms (Sparc) we have to keep new DecodeN node and
  2830         // use it to do implicit NULL check in address:
  2831         //
  2832         // decode_not_null narrow_oop_reg, base_reg
  2833         // [base_reg + offset]
  2834         // NullCheck base_reg
  2835         //
  2836         // Pin the new DecodeN node to non-null path on these platform (Sparc)
  2837         // to keep the information to which NULL check the new DecodeN node
  2838         // corresponds to use it as value in implicit_null_check().
  2839         //
  2840         new_in1->set_req(0, n->in(0));
  2843       n->subsume_by(new_in1, this);
  2844       if (in1->outcnt() == 0) {
  2845         in1->disconnect_inputs(NULL, this);
  2848     break;
  2850   case Op_CmpP:
  2851     // Do this transformation here to preserve CmpPNode::sub() and
  2852     // other TypePtr related Ideal optimizations (for example, ptr nullness).
  2853     if (n->in(1)->is_DecodeNarrowPtr() || n->in(2)->is_DecodeNarrowPtr()) {
  2854       Node* in1 = n->in(1);
  2855       Node* in2 = n->in(2);
  2856       if (!in1->is_DecodeNarrowPtr()) {
  2857         in2 = in1;
  2858         in1 = n->in(2);
  2860       assert(in1->is_DecodeNarrowPtr(), "sanity");
  2862       Node* new_in2 = NULL;
  2863       if (in2->is_DecodeNarrowPtr()) {
  2864         assert(in2->Opcode() == in1->Opcode(), "must be same node type");
  2865         new_in2 = in2->in(1);
  2866       } else if (in2->Opcode() == Op_ConP) {
  2867         const Type* t = in2->bottom_type();
  2868         if (t == TypePtr::NULL_PTR) {
  2869           assert(in1->is_DecodeN(), "compare klass to null?");
  2870           // Don't convert CmpP null check into CmpN if compressed
  2871           // oops implicit null check is not generated.
  2872           // This will allow to generate normal oop implicit null check.
  2873           if (Matcher::gen_narrow_oop_implicit_null_checks())
  2874             new_in2 = ConNode::make(this, TypeNarrowOop::NULL_PTR);
  2875           //
  2876           // This transformation together with CastPP transformation above
  2877           // will generated code for implicit NULL checks for compressed oops.
  2878           //
  2879           // The original code after Optimize()
  2880           //
  2881           //    LoadN memory, narrow_oop_reg
  2882           //    decode narrow_oop_reg, base_reg
  2883           //    CmpP base_reg, NULL
  2884           //    CastPP base_reg // NotNull
  2885           //    Load [base_reg + offset], val_reg
  2886           //
  2887           // after these transformations will be
  2888           //
  2889           //    LoadN memory, narrow_oop_reg
  2890           //    CmpN narrow_oop_reg, NULL
  2891           //    decode_not_null narrow_oop_reg, base_reg
  2892           //    Load [base_reg + offset], val_reg
  2893           //
  2894           // and the uncommon path (== NULL) will use narrow_oop_reg directly
  2895           // since narrow oops can be used in debug info now (see the code in
  2896           // final_graph_reshaping_walk()).
  2897           //
  2898           // At the end the code will be matched to
  2899           // on x86:
  2900           //
  2901           //    Load_narrow_oop memory, narrow_oop_reg
  2902           //    Load [R12 + narrow_oop_reg<<3 + offset], val_reg
  2903           //    NullCheck narrow_oop_reg
  2904           //
  2905           // and on sparc:
  2906           //
  2907           //    Load_narrow_oop memory, narrow_oop_reg
  2908           //    decode_not_null narrow_oop_reg, base_reg
  2909           //    Load [base_reg + offset], val_reg
  2910           //    NullCheck base_reg
  2911           //
  2912         } else if (t->isa_oopptr()) {
  2913           new_in2 = ConNode::make(this, t->make_narrowoop());
  2914         } else if (t->isa_klassptr()) {
  2915           new_in2 = ConNode::make(this, t->make_narrowklass());
  2918       if (new_in2 != NULL) {
  2919         Node* cmpN = new (this) CmpNNode(in1->in(1), new_in2);
  2920         n->subsume_by(cmpN, this);
  2921         if (in1->outcnt() == 0) {
  2922           in1->disconnect_inputs(NULL, this);
  2924         if (in2->outcnt() == 0) {
  2925           in2->disconnect_inputs(NULL, this);
  2929     break;
  2931   case Op_DecodeN:
  2932   case Op_DecodeNKlass:
  2933     assert(!n->in(1)->is_EncodeNarrowPtr(), "should be optimized out");
  2934     // DecodeN could be pinned when it can't be fold into
  2935     // an address expression, see the code for Op_CastPP above.
  2936     assert(n->in(0) == NULL || (UseCompressedOops && !Matcher::narrow_oop_use_complex_address()), "no control");
  2937     break;
  2939   case Op_EncodeP:
  2940   case Op_EncodePKlass: {
  2941     Node* in1 = n->in(1);
  2942     if (in1->is_DecodeNarrowPtr()) {
  2943       n->subsume_by(in1->in(1), this);
  2944     } else if (in1->Opcode() == Op_ConP) {
  2945       const Type* t = in1->bottom_type();
  2946       if (t == TypePtr::NULL_PTR) {
  2947         assert(t->isa_oopptr(), "null klass?");
  2948         n->subsume_by(ConNode::make(this, TypeNarrowOop::NULL_PTR), this);
  2949       } else if (t->isa_oopptr()) {
  2950         n->subsume_by(ConNode::make(this, t->make_narrowoop()), this);
  2951       } else if (t->isa_klassptr()) {
  2952         n->subsume_by(ConNode::make(this, t->make_narrowklass()), this);
  2955     if (in1->outcnt() == 0) {
  2956       in1->disconnect_inputs(NULL, this);
  2958     break;
  2961   case Op_Proj: {
  2962     if (OptimizeStringConcat) {
  2963       ProjNode* p = n->as_Proj();
  2964       if (p->_is_io_use) {
  2965         // Separate projections were used for the exception path which
  2966         // are normally removed by a late inline.  If it wasn't inlined
  2967         // then they will hang around and should just be replaced with
  2968         // the original one.
  2969         Node* proj = NULL;
  2970         // Replace with just one
  2971         for (SimpleDUIterator i(p->in(0)); i.has_next(); i.next()) {
  2972           Node *use = i.get();
  2973           if (use->is_Proj() && p != use && use->as_Proj()->_con == p->_con) {
  2974             proj = use;
  2975             break;
  2978         assert(proj != NULL, "must be found");
  2979         p->subsume_by(proj, this);
  2982     break;
  2985   case Op_Phi:
  2986     if (n->as_Phi()->bottom_type()->isa_narrowoop() || n->as_Phi()->bottom_type()->isa_narrowklass()) {
  2987       // The EncodeP optimization may create Phi with the same edges
  2988       // for all paths. It is not handled well by Register Allocator.
  2989       Node* unique_in = n->in(1);
  2990       assert(unique_in != NULL, "");
  2991       uint cnt = n->req();
  2992       for (uint i = 2; i < cnt; i++) {
  2993         Node* m = n->in(i);
  2994         assert(m != NULL, "");
  2995         if (unique_in != m)
  2996           unique_in = NULL;
  2998       if (unique_in != NULL) {
  2999         n->subsume_by(unique_in, this);
  3002     break;
  3004 #endif
  3006 #ifdef ASSERT
  3007   case Op_CastII:
  3008     // Verify that all range check dependent CastII nodes were removed.
  3009     if (n->isa_CastII()->has_range_check()) {
  3010       n->dump(3);
  3011       assert(false, "Range check dependent CastII node was not removed");
  3013     break;
  3014 #endif
  3016   case Op_ModI:
  3017     if (UseDivMod) {
  3018       // Check if a%b and a/b both exist
  3019       Node* d = n->find_similar(Op_DivI);
  3020       if (d) {
  3021         // Replace them with a fused divmod if supported
  3022         if (Matcher::has_match_rule(Op_DivModI)) {
  3023           DivModINode* divmod = DivModINode::make(this, n);
  3024           d->subsume_by(divmod->div_proj(), this);
  3025           n->subsume_by(divmod->mod_proj(), this);
  3026         } else {
  3027           // replace a%b with a-((a/b)*b)
  3028           Node* mult = new (this) MulINode(d, d->in(2));
  3029           Node* sub  = new (this) SubINode(d->in(1), mult);
  3030           n->subsume_by(sub, this);
  3034     break;
  3036   case Op_ModL:
  3037     if (UseDivMod) {
  3038       // Check if a%b and a/b both exist
  3039       Node* d = n->find_similar(Op_DivL);
  3040       if (d) {
  3041         // Replace them with a fused divmod if supported
  3042         if (Matcher::has_match_rule(Op_DivModL)) {
  3043           DivModLNode* divmod = DivModLNode::make(this, n);
  3044           d->subsume_by(divmod->div_proj(), this);
  3045           n->subsume_by(divmod->mod_proj(), this);
  3046         } else {
  3047           // replace a%b with a-((a/b)*b)
  3048           Node* mult = new (this) MulLNode(d, d->in(2));
  3049           Node* sub  = new (this) SubLNode(d->in(1), mult);
  3050           n->subsume_by(sub, this);
  3054     break;
  3056   case Op_LoadVector:
  3057   case Op_StoreVector:
  3058     break;
  3060   case Op_PackB:
  3061   case Op_PackS:
  3062   case Op_PackI:
  3063   case Op_PackF:
  3064   case Op_PackL:
  3065   case Op_PackD:
  3066     if (n->req()-1 > 2) {
  3067       // Replace many operand PackNodes with a binary tree for matching
  3068       PackNode* p = (PackNode*) n;
  3069       Node* btp = p->binary_tree_pack(this, 1, n->req());
  3070       n->subsume_by(btp, this);
  3072     break;
  3073   case Op_Loop:
  3074   case Op_CountedLoop:
  3075     if (n->as_Loop()->is_inner_loop()) {
  3076       frc.inc_inner_loop_count();
  3078     break;
  3079   case Op_LShiftI:
  3080   case Op_RShiftI:
  3081   case Op_URShiftI:
  3082   case Op_LShiftL:
  3083   case Op_RShiftL:
  3084   case Op_URShiftL:
  3085     if (Matcher::need_masked_shift_count) {
  3086       // The cpu's shift instructions don't restrict the count to the
  3087       // lower 5/6 bits. We need to do the masking ourselves.
  3088       Node* in2 = n->in(2);
  3089       juint mask = (n->bottom_type() == TypeInt::INT) ? (BitsPerInt - 1) : (BitsPerLong - 1);
  3090       const TypeInt* t = in2->find_int_type();
  3091       if (t != NULL && t->is_con()) {
  3092         juint shift = t->get_con();
  3093         if (shift > mask) { // Unsigned cmp
  3094           n->set_req(2, ConNode::make(this, TypeInt::make(shift & mask)));
  3096       } else {
  3097         if (t == NULL || t->_lo < 0 || t->_hi > (int)mask) {
  3098           Node* shift = new (this) AndINode(in2, ConNode::make(this, TypeInt::make(mask)));
  3099           n->set_req(2, shift);
  3102       if (in2->outcnt() == 0) { // Remove dead node
  3103         in2->disconnect_inputs(NULL, this);
  3106     break;
  3107   case Op_MemBarStoreStore:
  3108   case Op_MemBarRelease:
  3109     // Break the link with AllocateNode: it is no longer useful and
  3110     // confuses register allocation.
  3111     if (n->req() > MemBarNode::Precedent) {
  3112       n->set_req(MemBarNode::Precedent, top());
  3114     break;
  3115   default:
  3116     assert( !n->is_Call(), "" );
  3117     assert( !n->is_Mem(), "" );
  3118     assert( nop != Op_ProfileBoolean, "should be eliminated during IGVN");
  3119     break;
  3122   // Collect CFG split points
  3123   if (n->is_MultiBranch())
  3124     frc._tests.push(n);
  3127 //------------------------------final_graph_reshaping_walk---------------------
  3128 // Replacing Opaque nodes with their input in final_graph_reshaping_impl(),
  3129 // requires that the walk visits a node's inputs before visiting the node.
  3130 void Compile::final_graph_reshaping_walk( Node_Stack &nstack, Node *root, Final_Reshape_Counts &frc ) {
  3131   ResourceArea *area = Thread::current()->resource_area();
  3132   Unique_Node_List sfpt(area);
  3134   frc._visited.set(root->_idx); // first, mark node as visited
  3135   uint cnt = root->req();
  3136   Node *n = root;
  3137   uint  i = 0;
  3138   while (true) {
  3139     if (i < cnt) {
  3140       // Place all non-visited non-null inputs onto stack
  3141       Node* m = n->in(i);
  3142       ++i;
  3143       if (m != NULL && !frc._visited.test_set(m->_idx)) {
  3144         if (m->is_SafePoint() && m->as_SafePoint()->jvms() != NULL) {
  3145           // compute worst case interpreter size in case of a deoptimization
  3146           update_interpreter_frame_size(m->as_SafePoint()->jvms()->interpreter_frame_size());
  3148           sfpt.push(m);
  3150         cnt = m->req();
  3151         nstack.push(n, i); // put on stack parent and next input's index
  3152         n = m;
  3153         i = 0;
  3155     } else {
  3156       // Now do post-visit work
  3157       final_graph_reshaping_impl( n, frc );
  3158       if (nstack.is_empty())
  3159         break;             // finished
  3160       n = nstack.node();   // Get node from stack
  3161       cnt = n->req();
  3162       i = nstack.index();
  3163       nstack.pop();        // Shift to the next node on stack
  3167   // Skip next transformation if compressed oops are not used.
  3168   if ((UseCompressedOops && !Matcher::gen_narrow_oop_implicit_null_checks()) ||
  3169       (!UseCompressedOops && !UseCompressedClassPointers))
  3170     return;
  3172   // Go over safepoints nodes to skip DecodeN/DecodeNKlass nodes for debug edges.
  3173   // It could be done for an uncommon traps or any safepoints/calls
  3174   // if the DecodeN/DecodeNKlass node is referenced only in a debug info.
  3175   while (sfpt.size() > 0) {
  3176     n = sfpt.pop();
  3177     JVMState *jvms = n->as_SafePoint()->jvms();
  3178     assert(jvms != NULL, "sanity");
  3179     int start = jvms->debug_start();
  3180     int end   = n->req();
  3181     bool is_uncommon = (n->is_CallStaticJava() &&
  3182                         n->as_CallStaticJava()->uncommon_trap_request() != 0);
  3183     for (int j = start; j < end; j++) {
  3184       Node* in = n->in(j);
  3185       if (in->is_DecodeNarrowPtr()) {
  3186         bool safe_to_skip = true;
  3187         if (!is_uncommon ) {
  3188           // Is it safe to skip?
  3189           for (uint i = 0; i < in->outcnt(); i++) {
  3190             Node* u = in->raw_out(i);
  3191             if (!u->is_SafePoint() ||
  3192                  u->is_Call() && u->as_Call()->has_non_debug_use(n)) {
  3193               safe_to_skip = false;
  3197         if (safe_to_skip) {
  3198           n->set_req(j, in->in(1));
  3200         if (in->outcnt() == 0) {
  3201           in->disconnect_inputs(NULL, this);
  3208 //------------------------------final_graph_reshaping--------------------------
  3209 // Final Graph Reshaping.
  3210 //
  3211 // (1) Clone simple inputs to uncommon calls, so they can be scheduled late
  3212 //     and not commoned up and forced early.  Must come after regular
  3213 //     optimizations to avoid GVN undoing the cloning.  Clone constant
  3214 //     inputs to Loop Phis; these will be split by the allocator anyways.
  3215 //     Remove Opaque nodes.
  3216 // (2) Move last-uses by commutative operations to the left input to encourage
  3217 //     Intel update-in-place two-address operations and better register usage
  3218 //     on RISCs.  Must come after regular optimizations to avoid GVN Ideal
  3219 //     calls canonicalizing them back.
  3220 // (3) Count the number of double-precision FP ops, single-precision FP ops
  3221 //     and call sites.  On Intel, we can get correct rounding either by
  3222 //     forcing singles to memory (requires extra stores and loads after each
  3223 //     FP bytecode) or we can set a rounding mode bit (requires setting and
  3224 //     clearing the mode bit around call sites).  The mode bit is only used
  3225 //     if the relative frequency of single FP ops to calls is low enough.
  3226 //     This is a key transform for SPEC mpeg_audio.
  3227 // (4) Detect infinite loops; blobs of code reachable from above but not
  3228 //     below.  Several of the Code_Gen algorithms fail on such code shapes,
  3229 //     so we simply bail out.  Happens a lot in ZKM.jar, but also happens
  3230 //     from time to time in other codes (such as -Xcomp finalizer loops, etc).
  3231 //     Detection is by looking for IfNodes where only 1 projection is
  3232 //     reachable from below or CatchNodes missing some targets.
  3233 // (5) Assert for insane oop offsets in debug mode.
  3235 bool Compile::final_graph_reshaping() {
  3236   // an infinite loop may have been eliminated by the optimizer,
  3237   // in which case the graph will be empty.
  3238   if (root()->req() == 1) {
  3239     record_method_not_compilable("trivial infinite loop");
  3240     return true;
  3243   // Expensive nodes have their control input set to prevent the GVN
  3244   // from freely commoning them. There's no GVN beyond this point so
  3245   // no need to keep the control input. We want the expensive nodes to
  3246   // be freely moved to the least frequent code path by gcm.
  3247   assert(OptimizeExpensiveOps || expensive_count() == 0, "optimization off but list non empty?");
  3248   for (int i = 0; i < expensive_count(); i++) {
  3249     _expensive_nodes->at(i)->set_req(0, NULL);
  3252   Final_Reshape_Counts frc;
  3254   // Visit everybody reachable!
  3255   // Allocate stack of size C->live_nodes()/2 to avoid frequent realloc
  3256   Node_Stack nstack(live_nodes() >> 1);
  3257   final_graph_reshaping_walk(nstack, root(), frc);
  3259   // Check for unreachable (from below) code (i.e., infinite loops).
  3260   for( uint i = 0; i < frc._tests.size(); i++ ) {
  3261     MultiBranchNode *n = frc._tests[i]->as_MultiBranch();
  3262     // Get number of CFG targets.
  3263     // Note that PCTables include exception targets after calls.
  3264     uint required_outcnt = n->required_outcnt();
  3265     if (n->outcnt() != required_outcnt) {
  3266       // Check for a few special cases.  Rethrow Nodes never take the
  3267       // 'fall-thru' path, so expected kids is 1 less.
  3268       if (n->is_PCTable() && n->in(0) && n->in(0)->in(0)) {
  3269         if (n->in(0)->in(0)->is_Call()) {
  3270           CallNode *call = n->in(0)->in(0)->as_Call();
  3271           if (call->entry_point() == OptoRuntime::rethrow_stub()) {
  3272             required_outcnt--;      // Rethrow always has 1 less kid
  3273           } else if (call->req() > TypeFunc::Parms &&
  3274                      call->is_CallDynamicJava()) {
  3275             // Check for null receiver. In such case, the optimizer has
  3276             // detected that the virtual call will always result in a null
  3277             // pointer exception. The fall-through projection of this CatchNode
  3278             // will not be populated.
  3279             Node *arg0 = call->in(TypeFunc::Parms);
  3280             if (arg0->is_Type() &&
  3281                 arg0->as_Type()->type()->higher_equal(TypePtr::NULL_PTR)) {
  3282               required_outcnt--;
  3284           } else if (call->entry_point() == OptoRuntime::new_array_Java() &&
  3285                      call->req() > TypeFunc::Parms+1 &&
  3286                      call->is_CallStaticJava()) {
  3287             // Check for negative array length. In such case, the optimizer has
  3288             // detected that the allocation attempt will always result in an
  3289             // exception. There is no fall-through projection of this CatchNode .
  3290             Node *arg1 = call->in(TypeFunc::Parms+1);
  3291             if (arg1->is_Type() &&
  3292                 arg1->as_Type()->type()->join(TypeInt::POS)->empty()) {
  3293               required_outcnt--;
  3298       // Recheck with a better notion of 'required_outcnt'
  3299       if (n->outcnt() != required_outcnt) {
  3300         record_method_not_compilable("malformed control flow");
  3301         return true;            // Not all targets reachable!
  3304     // Check that I actually visited all kids.  Unreached kids
  3305     // must be infinite loops.
  3306     for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++)
  3307       if (!frc._visited.test(n->fast_out(j)->_idx)) {
  3308         record_method_not_compilable("infinite loop");
  3309         return true;            // Found unvisited kid; must be unreach
  3313   // If original bytecodes contained a mixture of floats and doubles
  3314   // check if the optimizer has made it homogenous, item (3).
  3315   if( Use24BitFPMode && Use24BitFP && UseSSE == 0 &&
  3316       frc.get_float_count() > 32 &&
  3317       frc.get_double_count() == 0 &&
  3318       (10 * frc.get_call_count() < frc.get_float_count()) ) {
  3319     set_24_bit_selection_and_mode( false,  true );
  3322   set_java_calls(frc.get_java_call_count());
  3323   set_inner_loops(frc.get_inner_loop_count());
  3325   // No infinite loops, no reason to bail out.
  3326   return false;
  3329 //-----------------------------too_many_traps----------------------------------
  3330 // Report if there are too many traps at the current method and bci.
  3331 // Return true if there was a trap, and/or PerMethodTrapLimit is exceeded.
  3332 bool Compile::too_many_traps(ciMethod* method,
  3333                              int bci,
  3334                              Deoptimization::DeoptReason reason) {
  3335   ciMethodData* md = method->method_data();
  3336   if (md->is_empty()) {
  3337     // Assume the trap has not occurred, or that it occurred only
  3338     // because of a transient condition during start-up in the interpreter.
  3339     return false;
  3341   ciMethod* m = Deoptimization::reason_is_speculate(reason) ? this->method() : NULL;
  3342   if (md->has_trap_at(bci, m, reason) != 0) {
  3343     // Assume PerBytecodeTrapLimit==0, for a more conservative heuristic.
  3344     // Also, if there are multiple reasons, or if there is no per-BCI record,
  3345     // assume the worst.
  3346     if (log())
  3347       log()->elem("observe trap='%s' count='%d'",
  3348                   Deoptimization::trap_reason_name(reason),
  3349                   md->trap_count(reason));
  3350     return true;
  3351   } else {
  3352     // Ignore method/bci and see if there have been too many globally.
  3353     return too_many_traps(reason, md);
  3357 // Less-accurate variant which does not require a method and bci.
  3358 bool Compile::too_many_traps(Deoptimization::DeoptReason reason,
  3359                              ciMethodData* logmd) {
  3360   if (trap_count(reason) >= Deoptimization::per_method_trap_limit(reason)) {
  3361     // Too many traps globally.
  3362     // Note that we use cumulative trap_count, not just md->trap_count.
  3363     if (log()) {
  3364       int mcount = (logmd == NULL)? -1: (int)logmd->trap_count(reason);
  3365       log()->elem("observe trap='%s' count='0' mcount='%d' ccount='%d'",
  3366                   Deoptimization::trap_reason_name(reason),
  3367                   mcount, trap_count(reason));
  3369     return true;
  3370   } else {
  3371     // The coast is clear.
  3372     return false;
  3376 //--------------------------too_many_recompiles--------------------------------
  3377 // Report if there are too many recompiles at the current method and bci.
  3378 // Consults PerBytecodeRecompilationCutoff and PerMethodRecompilationCutoff.
  3379 // Is not eager to return true, since this will cause the compiler to use
  3380 // Action_none for a trap point, to avoid too many recompilations.
  3381 bool Compile::too_many_recompiles(ciMethod* method,
  3382                                   int bci,
  3383                                   Deoptimization::DeoptReason reason) {
  3384   ciMethodData* md = method->method_data();
  3385   if (md->is_empty()) {
  3386     // Assume the trap has not occurred, or that it occurred only
  3387     // because of a transient condition during start-up in the interpreter.
  3388     return false;
  3390   // Pick a cutoff point well within PerBytecodeRecompilationCutoff.
  3391   uint bc_cutoff = (uint) PerBytecodeRecompilationCutoff / 8;
  3392   uint m_cutoff  = (uint) PerMethodRecompilationCutoff / 2 + 1;  // not zero
  3393   Deoptimization::DeoptReason per_bc_reason
  3394     = Deoptimization::reason_recorded_per_bytecode_if_any(reason);
  3395   ciMethod* m = Deoptimization::reason_is_speculate(reason) ? this->method() : NULL;
  3396   if ((per_bc_reason == Deoptimization::Reason_none
  3397        || md->has_trap_at(bci, m, reason) != 0)
  3398       // The trap frequency measure we care about is the recompile count:
  3399       && md->trap_recompiled_at(bci, m)
  3400       && md->overflow_recompile_count() >= bc_cutoff) {
  3401     // Do not emit a trap here if it has already caused recompilations.
  3402     // Also, if there are multiple reasons, or if there is no per-BCI record,
  3403     // assume the worst.
  3404     if (log())
  3405       log()->elem("observe trap='%s recompiled' count='%d' recompiles2='%d'",
  3406                   Deoptimization::trap_reason_name(reason),
  3407                   md->trap_count(reason),
  3408                   md->overflow_recompile_count());
  3409     return true;
  3410   } else if (trap_count(reason) != 0
  3411              && decompile_count() >= m_cutoff) {
  3412     // Too many recompiles globally, and we have seen this sort of trap.
  3413     // Use cumulative decompile_count, not just md->decompile_count.
  3414     if (log())
  3415       log()->elem("observe trap='%s' count='%d' mcount='%d' decompiles='%d' mdecompiles='%d'",
  3416                   Deoptimization::trap_reason_name(reason),
  3417                   md->trap_count(reason), trap_count(reason),
  3418                   md->decompile_count(), decompile_count());
  3419     return true;
  3420   } else {
  3421     // The coast is clear.
  3422     return false;
  3426 // Compute when not to trap. Used by matching trap based nodes and
  3427 // NullCheck optimization.
  3428 void Compile::set_allowed_deopt_reasons() {
  3429   _allowed_reasons = 0;
  3430   if (is_method_compilation()) {
  3431     for (int rs = (int)Deoptimization::Reason_none+1; rs < Compile::trapHistLength; rs++) {
  3432       assert(rs < BitsPerInt, "recode bit map");
  3433       if (!too_many_traps((Deoptimization::DeoptReason) rs)) {
  3434         _allowed_reasons |= nth_bit(rs);
  3440 #ifndef PRODUCT
  3441 //------------------------------verify_graph_edges---------------------------
  3442 // Walk the Graph and verify that there is a one-to-one correspondence
  3443 // between Use-Def edges and Def-Use edges in the graph.
  3444 void Compile::verify_graph_edges(bool no_dead_code) {
  3445   if (VerifyGraphEdges) {
  3446     ResourceArea *area = Thread::current()->resource_area();
  3447     Unique_Node_List visited(area);
  3448     // Call recursive graph walk to check edges
  3449     _root->verify_edges(visited);
  3450     if (no_dead_code) {
  3451       // Now make sure that no visited node is used by an unvisited node.
  3452       bool dead_nodes = 0;
  3453       Unique_Node_List checked(area);
  3454       while (visited.size() > 0) {
  3455         Node* n = visited.pop();
  3456         checked.push(n);
  3457         for (uint i = 0; i < n->outcnt(); i++) {
  3458           Node* use = n->raw_out(i);
  3459           if (checked.member(use))  continue;  // already checked
  3460           if (visited.member(use))  continue;  // already in the graph
  3461           if (use->is_Con())        continue;  // a dead ConNode is OK
  3462           // At this point, we have found a dead node which is DU-reachable.
  3463           if (dead_nodes++ == 0)
  3464             tty->print_cr("*** Dead nodes reachable via DU edges:");
  3465           use->dump(2);
  3466           tty->print_cr("---");
  3467           checked.push(use);  // No repeats; pretend it is now checked.
  3470       assert(dead_nodes == 0, "using nodes must be reachable from root");
  3475 // Verify GC barriers consistency
  3476 // Currently supported:
  3477 // - G1 pre-barriers (see GraphKit::g1_write_barrier_pre())
  3478 void Compile::verify_barriers() {
  3479   if (UseG1GC) {
  3480     // Verify G1 pre-barriers
  3481     const int marking_offset = in_bytes(JavaThread::satb_mark_queue_offset() + PtrQueue::byte_offset_of_active());
  3483     ResourceArea *area = Thread::current()->resource_area();
  3484     Unique_Node_List visited(area);
  3485     Node_List worklist(area);
  3486     // We're going to walk control flow backwards starting from the Root
  3487     worklist.push(_root);
  3488     while (worklist.size() > 0) {
  3489       Node* x = worklist.pop();
  3490       if (x == NULL || x == top()) continue;
  3491       if (visited.member(x)) {
  3492         continue;
  3493       } else {
  3494         visited.push(x);
  3497       if (x->is_Region()) {
  3498         for (uint i = 1; i < x->req(); i++) {
  3499           worklist.push(x->in(i));
  3501       } else {
  3502         worklist.push(x->in(0));
  3503         // We are looking for the pattern:
  3504         //                            /->ThreadLocal
  3505         // If->Bool->CmpI->LoadB->AddP->ConL(marking_offset)
  3506         //              \->ConI(0)
  3507         // We want to verify that the If and the LoadB have the same control
  3508         // See GraphKit::g1_write_barrier_pre()
  3509         if (x->is_If()) {
  3510           IfNode *iff = x->as_If();
  3511           if (iff->in(1)->is_Bool() && iff->in(1)->in(1)->is_Cmp()) {
  3512             CmpNode *cmp = iff->in(1)->in(1)->as_Cmp();
  3513             if (cmp->Opcode() == Op_CmpI && cmp->in(2)->is_Con() && cmp->in(2)->bottom_type()->is_int()->get_con() == 0
  3514                 && cmp->in(1)->is_Load()) {
  3515               LoadNode* load = cmp->in(1)->as_Load();
  3516               if (load->Opcode() == Op_LoadB && load->in(2)->is_AddP() && load->in(2)->in(2)->Opcode() == Op_ThreadLocal
  3517                   && load->in(2)->in(3)->is_Con()
  3518                   && load->in(2)->in(3)->bottom_type()->is_intptr_t()->get_con() == marking_offset) {
  3520                 Node* if_ctrl = iff->in(0);
  3521                 Node* load_ctrl = load->in(0);
  3523                 if (if_ctrl != load_ctrl) {
  3524                   // Skip possible CProj->NeverBranch in infinite loops
  3525                   if ((if_ctrl->is_Proj() && if_ctrl->Opcode() == Op_CProj)
  3526                       && (if_ctrl->in(0)->is_MultiBranch() && if_ctrl->in(0)->Opcode() == Op_NeverBranch)) {
  3527                     if_ctrl = if_ctrl->in(0)->in(0);
  3530                 assert(load_ctrl != NULL && if_ctrl == load_ctrl, "controls must match");
  3540 #endif
  3542 // The Compile object keeps track of failure reasons separately from the ciEnv.
  3543 // This is required because there is not quite a 1-1 relation between the
  3544 // ciEnv and its compilation task and the Compile object.  Note that one
  3545 // ciEnv might use two Compile objects, if C2Compiler::compile_method decides
  3546 // to backtrack and retry without subsuming loads.  Other than this backtracking
  3547 // behavior, the Compile's failure reason is quietly copied up to the ciEnv
  3548 // by the logic in C2Compiler.
  3549 void Compile::record_failure(const char* reason) {
  3550   if (log() != NULL) {
  3551     log()->elem("failure reason='%s' phase='compile'", reason);
  3553   if (_failure_reason == NULL) {
  3554     // Record the first failure reason.
  3555     _failure_reason = reason;
  3558   EventCompilerFailure event;
  3559   if (event.should_commit()) {
  3560     event.set_compileID(Compile::compile_id());
  3561     event.set_failure(reason);
  3562     event.commit();
  3565   if (!C->failure_reason_is(C2Compiler::retry_no_subsuming_loads())) {
  3566     C->print_method(PHASE_FAILURE);
  3568   _root = NULL;  // flush the graph, too
  3571 Compile::TracePhase::TracePhase(const char* name, elapsedTimer* accumulator, bool dolog)
  3572   : TraceTime(NULL, accumulator, false NOT_PRODUCT( || TimeCompiler ), false),
  3573     _phase_name(name), _dolog(dolog)
  3575   if (dolog) {
  3576     C = Compile::current();
  3577     _log = C->log();
  3578   } else {
  3579     C = NULL;
  3580     _log = NULL;
  3582   if (_log != NULL) {
  3583     _log->begin_head("phase name='%s' nodes='%d' live='%d'", _phase_name, C->unique(), C->live_nodes());
  3584     _log->stamp();
  3585     _log->end_head();
  3589 Compile::TracePhase::~TracePhase() {
  3591   C = Compile::current();
  3592   if (_dolog) {
  3593     _log = C->log();
  3594   } else {
  3595     _log = NULL;
  3598 #ifdef ASSERT
  3599   if (PrintIdealNodeCount) {
  3600     tty->print_cr("phase name='%s' nodes='%d' live='%d' live_graph_walk='%d'",
  3601                   _phase_name, C->unique(), C->live_nodes(), C->count_live_nodes_by_graph_walk());
  3604   if (VerifyIdealNodeCount) {
  3605     Compile::current()->print_missing_nodes();
  3607 #endif
  3609   if (_log != NULL) {
  3610     _log->done("phase name='%s' nodes='%d' live='%d'", _phase_name, C->unique(), C->live_nodes());
  3614 //=============================================================================
  3615 // Two Constant's are equal when the type and the value are equal.
  3616 bool Compile::Constant::operator==(const Constant& other) {
  3617   if (type()          != other.type()         )  return false;
  3618   if (can_be_reused() != other.can_be_reused())  return false;
  3619   // For floating point values we compare the bit pattern.
  3620   switch (type()) {
  3621   case T_FLOAT:   return (_v._value.i == other._v._value.i);
  3622   case T_LONG:
  3623   case T_DOUBLE:  return (_v._value.j == other._v._value.j);
  3624   case T_OBJECT:
  3625   case T_ADDRESS: return (_v._value.l == other._v._value.l);
  3626   case T_VOID:    return (_v._value.l == other._v._value.l);  // jump-table entries
  3627   case T_METADATA: return (_v._metadata == other._v._metadata);
  3628   default: ShouldNotReachHere();
  3630   return false;
  3633 static int type_to_size_in_bytes(BasicType t) {
  3634   switch (t) {
  3635   case T_LONG:    return sizeof(jlong  );
  3636   case T_FLOAT:   return sizeof(jfloat );
  3637   case T_DOUBLE:  return sizeof(jdouble);
  3638   case T_METADATA: return sizeof(Metadata*);
  3639     // We use T_VOID as marker for jump-table entries (labels) which
  3640     // need an internal word relocation.
  3641   case T_VOID:
  3642   case T_ADDRESS:
  3643   case T_OBJECT:  return sizeof(jobject);
  3646   ShouldNotReachHere();
  3647   return -1;
  3650 int Compile::ConstantTable::qsort_comparator(Constant* a, Constant* b) {
  3651   // sort descending
  3652   if (a->freq() > b->freq())  return -1;
  3653   if (a->freq() < b->freq())  return  1;
  3654   return 0;
  3657 void Compile::ConstantTable::calculate_offsets_and_size() {
  3658   // First, sort the array by frequencies.
  3659   _constants.sort(qsort_comparator);
  3661 #ifdef ASSERT
  3662   // Make sure all jump-table entries were sorted to the end of the
  3663   // array (they have a negative frequency).
  3664   bool found_void = false;
  3665   for (int i = 0; i < _constants.length(); i++) {
  3666     Constant con = _constants.at(i);
  3667     if (con.type() == T_VOID)
  3668       found_void = true;  // jump-tables
  3669     else
  3670       assert(!found_void, "wrong sorting");
  3672 #endif
  3674   int offset = 0;
  3675   for (int i = 0; i < _constants.length(); i++) {
  3676     Constant* con = _constants.adr_at(i);
  3678     // Align offset for type.
  3679     int typesize = type_to_size_in_bytes(con->type());
  3680     offset = align_size_up(offset, typesize);
  3681     con->set_offset(offset);   // set constant's offset
  3683     if (con->type() == T_VOID) {
  3684       MachConstantNode* n = (MachConstantNode*) con->get_jobject();
  3685       offset = offset + typesize * n->outcnt();  // expand jump-table
  3686     } else {
  3687       offset = offset + typesize;
  3691   // Align size up to the next section start (which is insts; see
  3692   // CodeBuffer::align_at_start).
  3693   assert(_size == -1, "already set?");
  3694   _size = align_size_up(offset, CodeEntryAlignment);
  3697 void Compile::ConstantTable::emit(CodeBuffer& cb) {
  3698   MacroAssembler _masm(&cb);
  3699   for (int i = 0; i < _constants.length(); i++) {
  3700     Constant con = _constants.at(i);
  3701     address constant_addr;
  3702     switch (con.type()) {
  3703     case T_LONG:   constant_addr = _masm.long_constant(  con.get_jlong()  ); break;
  3704     case T_FLOAT:  constant_addr = _masm.float_constant( con.get_jfloat() ); break;
  3705     case T_DOUBLE: constant_addr = _masm.double_constant(con.get_jdouble()); break;
  3706     case T_OBJECT: {
  3707       jobject obj = con.get_jobject();
  3708       int oop_index = _masm.oop_recorder()->find_index(obj);
  3709       constant_addr = _masm.address_constant((address) obj, oop_Relocation::spec(oop_index));
  3710       break;
  3712     case T_ADDRESS: {
  3713       address addr = (address) con.get_jobject();
  3714       constant_addr = _masm.address_constant(addr);
  3715       break;
  3717     // We use T_VOID as marker for jump-table entries (labels) which
  3718     // need an internal word relocation.
  3719     case T_VOID: {
  3720       MachConstantNode* n = (MachConstantNode*) con.get_jobject();
  3721       // Fill the jump-table with a dummy word.  The real value is
  3722       // filled in later in fill_jump_table.
  3723       address dummy = (address) n;
  3724       constant_addr = _masm.address_constant(dummy);
  3725       // Expand jump-table
  3726       for (uint i = 1; i < n->outcnt(); i++) {
  3727         address temp_addr = _masm.address_constant(dummy + i);
  3728         assert(temp_addr, "consts section too small");
  3730       break;
  3732     case T_METADATA: {
  3733       Metadata* obj = con.get_metadata();
  3734       int metadata_index = _masm.oop_recorder()->find_index(obj);
  3735       constant_addr = _masm.address_constant((address) obj, metadata_Relocation::spec(metadata_index));
  3736       break;
  3738     default: ShouldNotReachHere();
  3740     assert(constant_addr, "consts section too small");
  3741     assert((constant_addr - _masm.code()->consts()->start()) == con.offset(),
  3742             err_msg_res("must be: %d == %d", (int) (constant_addr - _masm.code()->consts()->start()), (int)(con.offset())));
  3746 int Compile::ConstantTable::find_offset(Constant& con) const {
  3747   int idx = _constants.find(con);
  3748   assert(idx != -1, "constant must be in constant table");
  3749   int offset = _constants.at(idx).offset();
  3750   assert(offset != -1, "constant table not emitted yet?");
  3751   return offset;
  3754 void Compile::ConstantTable::add(Constant& con) {
  3755   if (con.can_be_reused()) {
  3756     int idx = _constants.find(con);
  3757     if (idx != -1 && _constants.at(idx).can_be_reused()) {
  3758       _constants.adr_at(idx)->inc_freq(con.freq());  // increase the frequency by the current value
  3759       return;
  3762   (void) _constants.append(con);
  3765 Compile::Constant Compile::ConstantTable::add(MachConstantNode* n, BasicType type, jvalue value) {
  3766   Block* b = Compile::current()->cfg()->get_block_for_node(n);
  3767   Constant con(type, value, b->_freq);
  3768   add(con);
  3769   return con;
  3772 Compile::Constant Compile::ConstantTable::add(Metadata* metadata) {
  3773   Constant con(metadata);
  3774   add(con);
  3775   return con;
  3778 Compile::Constant Compile::ConstantTable::add(MachConstantNode* n, MachOper* oper) {
  3779   jvalue value;
  3780   BasicType type = oper->type()->basic_type();
  3781   switch (type) {
  3782   case T_LONG:    value.j = oper->constantL(); break;
  3783   case T_FLOAT:   value.f = oper->constantF(); break;
  3784   case T_DOUBLE:  value.d = oper->constantD(); break;
  3785   case T_OBJECT:
  3786   case T_ADDRESS: value.l = (jobject) oper->constant(); break;
  3787   case T_METADATA: return add((Metadata*)oper->constant()); break;
  3788   default: guarantee(false, err_msg_res("unhandled type: %s", type2name(type)));
  3790   return add(n, type, value);
  3793 Compile::Constant Compile::ConstantTable::add_jump_table(MachConstantNode* n) {
  3794   jvalue value;
  3795   // We can use the node pointer here to identify the right jump-table
  3796   // as this method is called from Compile::Fill_buffer right before
  3797   // the MachNodes are emitted and the jump-table is filled (means the
  3798   // MachNode pointers do not change anymore).
  3799   value.l = (jobject) n;
  3800   Constant con(T_VOID, value, next_jump_table_freq(), false);  // Labels of a jump-table cannot be reused.
  3801   add(con);
  3802   return con;
  3805 void Compile::ConstantTable::fill_jump_table(CodeBuffer& cb, MachConstantNode* n, GrowableArray<Label*> labels) const {
  3806   // If called from Compile::scratch_emit_size do nothing.
  3807   if (Compile::current()->in_scratch_emit_size())  return;
  3809   assert(labels.is_nonempty(), "must be");
  3810   assert((uint) labels.length() == n->outcnt(), err_msg_res("must be equal: %d == %d", labels.length(), n->outcnt()));
  3812   // Since MachConstantNode::constant_offset() also contains
  3813   // table_base_offset() we need to subtract the table_base_offset()
  3814   // to get the plain offset into the constant table.
  3815   int offset = n->constant_offset() - table_base_offset();
  3817   MacroAssembler _masm(&cb);
  3818   address* jump_table_base = (address*) (_masm.code()->consts()->start() + offset);
  3820   for (uint i = 0; i < n->outcnt(); i++) {
  3821     address* constant_addr = &jump_table_base[i];
  3822     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)));
  3823     *constant_addr = cb.consts()->target(*labels.at(i), (address) constant_addr);
  3824     cb.consts()->relocate((address) constant_addr, relocInfo::internal_word_type);
  3828 void Compile::dump_inlining() {
  3829   if (print_inlining() || print_intrinsics()) {
  3830     // Print inlining message for candidates that we couldn't inline
  3831     // for lack of space or non constant receiver
  3832     for (int i = 0; i < _late_inlines.length(); i++) {
  3833       CallGenerator* cg = _late_inlines.at(i);
  3834       cg->print_inlining_late("live nodes > LiveNodeCountInliningCutoff");
  3836     Unique_Node_List useful;
  3837     useful.push(root());
  3838     for (uint next = 0; next < useful.size(); ++next) {
  3839       Node* n  = useful.at(next);
  3840       if (n->is_Call() && n->as_Call()->generator() != NULL && n->as_Call()->generator()->call_node() == n) {
  3841         CallNode* call = n->as_Call();
  3842         CallGenerator* cg = call->generator();
  3843         cg->print_inlining_late("receiver not constant");
  3845       uint max = n->len();
  3846       for ( uint i = 0; i < max; ++i ) {
  3847         Node *m = n->in(i);
  3848         if ( m == NULL ) continue;
  3849         useful.push(m);
  3852     for (int i = 0; i < _print_inlining_list->length(); i++) {
  3853       tty->print("%s", _print_inlining_list->adr_at(i)->ss()->as_string());
  3858 // Dump inlining replay data to the stream.
  3859 // Don't change thread state and acquire any locks.
  3860 void Compile::dump_inline_data(outputStream* out) {
  3861   InlineTree* inl_tree = ilt();
  3862   if (inl_tree != NULL) {
  3863     out->print(" inline %d", inl_tree->count());
  3864     inl_tree->dump_replay_data(out);
  3868 int Compile::cmp_expensive_nodes(Node* n1, Node* n2) {
  3869   if (n1->Opcode() < n2->Opcode())      return -1;
  3870   else if (n1->Opcode() > n2->Opcode()) return 1;
  3872   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()));
  3873   for (uint i = 1; i < n1->req(); i++) {
  3874     if (n1->in(i) < n2->in(i))      return -1;
  3875     else if (n1->in(i) > n2->in(i)) return 1;
  3878   return 0;
  3881 int Compile::cmp_expensive_nodes(Node** n1p, Node** n2p) {
  3882   Node* n1 = *n1p;
  3883   Node* n2 = *n2p;
  3885   return cmp_expensive_nodes(n1, n2);
  3888 void Compile::sort_expensive_nodes() {
  3889   if (!expensive_nodes_sorted()) {
  3890     _expensive_nodes->sort(cmp_expensive_nodes);
  3894 bool Compile::expensive_nodes_sorted() const {
  3895   for (int i = 1; i < _expensive_nodes->length(); i++) {
  3896     if (cmp_expensive_nodes(_expensive_nodes->adr_at(i), _expensive_nodes->adr_at(i-1)) < 0) {
  3897       return false;
  3900   return true;
  3903 bool Compile::should_optimize_expensive_nodes(PhaseIterGVN &igvn) {
  3904   if (_expensive_nodes->length() == 0) {
  3905     return false;
  3908   assert(OptimizeExpensiveOps, "optimization off?");
  3910   // Take this opportunity to remove dead nodes from the list
  3911   int j = 0;
  3912   for (int i = 0; i < _expensive_nodes->length(); i++) {
  3913     Node* n = _expensive_nodes->at(i);
  3914     if (!n->is_unreachable(igvn)) {
  3915       assert(n->is_expensive(), "should be expensive");
  3916       _expensive_nodes->at_put(j, n);
  3917       j++;
  3920   _expensive_nodes->trunc_to(j);
  3922   // Then sort the list so that similar nodes are next to each other
  3923   // and check for at least two nodes of identical kind with same data
  3924   // inputs.
  3925   sort_expensive_nodes();
  3927   for (int i = 0; i < _expensive_nodes->length()-1; i++) {
  3928     if (cmp_expensive_nodes(_expensive_nodes->adr_at(i), _expensive_nodes->adr_at(i+1)) == 0) {
  3929       return true;
  3933   return false;
  3936 void Compile::cleanup_expensive_nodes(PhaseIterGVN &igvn) {
  3937   if (_expensive_nodes->length() == 0) {
  3938     return;
  3941   assert(OptimizeExpensiveOps, "optimization off?");
  3943   // Sort to bring similar nodes next to each other and clear the
  3944   // control input of nodes for which there's only a single copy.
  3945   sort_expensive_nodes();
  3947   int j = 0;
  3948   int identical = 0;
  3949   int i = 0;
  3950   for (; i < _expensive_nodes->length()-1; i++) {
  3951     assert(j <= i, "can't write beyond current index");
  3952     if (_expensive_nodes->at(i)->Opcode() == _expensive_nodes->at(i+1)->Opcode()) {
  3953       identical++;
  3954       _expensive_nodes->at_put(j++, _expensive_nodes->at(i));
  3955       continue;
  3957     if (identical > 0) {
  3958       _expensive_nodes->at_put(j++, _expensive_nodes->at(i));
  3959       identical = 0;
  3960     } else {
  3961       Node* n = _expensive_nodes->at(i);
  3962       igvn.hash_delete(n);
  3963       n->set_req(0, NULL);
  3964       igvn.hash_insert(n);
  3967   if (identical > 0) {
  3968     _expensive_nodes->at_put(j++, _expensive_nodes->at(i));
  3969   } else if (_expensive_nodes->length() >= 1) {
  3970     Node* n = _expensive_nodes->at(i);
  3971     igvn.hash_delete(n);
  3972     n->set_req(0, NULL);
  3973     igvn.hash_insert(n);
  3975   _expensive_nodes->trunc_to(j);
  3978 void Compile::add_expensive_node(Node * n) {
  3979   assert(!_expensive_nodes->contains(n), "duplicate entry in expensive list");
  3980   assert(n->is_expensive(), "expensive nodes with non-null control here only");
  3981   assert(!n->is_CFG() && !n->is_Mem(), "no cfg or memory nodes here");
  3982   if (OptimizeExpensiveOps) {
  3983     _expensive_nodes->append(n);
  3984   } else {
  3985     // Clear control input and let IGVN optimize expensive nodes if
  3986     // OptimizeExpensiveOps is off.
  3987     n->set_req(0, NULL);
  3991 /**
  3992  * Remove the speculative part of types and clean up the graph
  3993  */
  3994 void Compile::remove_speculative_types(PhaseIterGVN &igvn) {
  3995   if (UseTypeSpeculation) {
  3996     Unique_Node_List worklist;
  3997     worklist.push(root());
  3998     int modified = 0;
  3999     // Go over all type nodes that carry a speculative type, drop the
  4000     // speculative part of the type and enqueue the node for an igvn
  4001     // which may optimize it out.
  4002     for (uint next = 0; next < worklist.size(); ++next) {
  4003       Node *n  = worklist.at(next);
  4004       if (n->is_Type()) {
  4005         TypeNode* tn = n->as_Type();
  4006         const Type* t = tn->type();
  4007         const Type* t_no_spec = t->remove_speculative();
  4008         if (t_no_spec != t) {
  4009           bool in_hash = igvn.hash_delete(n);
  4010           assert(in_hash, "node should be in igvn hash table");
  4011           tn->set_type(t_no_spec);
  4012           igvn.hash_insert(n);
  4013           igvn._worklist.push(n); // give it a chance to go away
  4014           modified++;
  4017       uint max = n->len();
  4018       for( uint i = 0; i < max; ++i ) {
  4019         Node *m = n->in(i);
  4020         if (not_a_node(m))  continue;
  4021         worklist.push(m);
  4024     // Drop the speculative part of all types in the igvn's type table
  4025     igvn.remove_speculative_types();
  4026     if (modified > 0) {
  4027       igvn.optimize();
  4029 #ifdef ASSERT
  4030     // Verify that after the IGVN is over no speculative type has resurfaced
  4031     worklist.clear();
  4032     worklist.push(root());
  4033     for (uint next = 0; next < worklist.size(); ++next) {
  4034       Node *n  = worklist.at(next);
  4035       const Type* t = igvn.type_or_null(n);
  4036       assert((t == NULL) || (t == t->remove_speculative()), "no more speculative types");
  4037       if (n->is_Type()) {
  4038         t = n->as_Type()->type();
  4039         assert(t == t->remove_speculative(), "no more speculative types");
  4041       uint max = n->len();
  4042       for( uint i = 0; i < max; ++i ) {
  4043         Node *m = n->in(i);
  4044         if (not_a_node(m))  continue;
  4045         worklist.push(m);
  4048     igvn.check_no_speculative_types();
  4049 #endif
  4053 // Convert integer value to a narrowed long type dependent on ctrl (for example, a range check)
  4054 Node* Compile::constrained_convI2L(PhaseGVN* phase, Node* value, const TypeInt* itype, Node* ctrl) {
  4055   if (ctrl != NULL) {
  4056     // Express control dependency by a CastII node with a narrow type.
  4057     value = new (phase->C) CastIINode(value, itype, false, true /* range check dependency */);
  4058     // Make the CastII node dependent on the control input to prevent the narrowed ConvI2L
  4059     // node from floating above the range check during loop optimizations. Otherwise, the
  4060     // ConvI2L node may be eliminated independently of the range check, causing the data path
  4061     // to become TOP while the control path is still there (although it's unreachable).
  4062     value->set_req(0, ctrl);
  4063     // Save CastII node to remove it after loop optimizations.
  4064     phase->C->add_range_check_cast(value);
  4065     value = phase->transform(value);
  4067   const TypeLong* ltype = TypeLong::make(itype->_lo, itype->_hi, itype->_widen);
  4068   return phase->transform(new (phase->C) ConvI2LNode(value, ltype));
  4071 // Auxiliary method to support randomized stressing/fuzzing.
  4072 //
  4073 // This method can be called the arbitrary number of times, with current count
  4074 // as the argument. The logic allows selecting a single candidate from the
  4075 // running list of candidates as follows:
  4076 //    int count = 0;
  4077 //    Cand* selected = null;
  4078 //    while(cand = cand->next()) {
  4079 //      if (randomized_select(++count)) {
  4080 //        selected = cand;
  4081 //      }
  4082 //    }
  4083 //
  4084 // Including count equalizes the chances any candidate is "selected".
  4085 // This is useful when we don't have the complete list of candidates to choose
  4086 // from uniformly. In this case, we need to adjust the randomicity of the
  4087 // selection, or else we will end up biasing the selection towards the latter
  4088 // candidates.
  4089 //
  4090 // Quick back-envelope calculation shows that for the list of n candidates
  4091 // the equal probability for the candidate to persist as "best" can be
  4092 // achieved by replacing it with "next" k-th candidate with the probability
  4093 // of 1/k. It can be easily shown that by the end of the run, the
  4094 // probability for any candidate is converged to 1/n, thus giving the
  4095 // uniform distribution among all the candidates.
  4096 //
  4097 // We don't care about the domain size as long as (RANDOMIZED_DOMAIN / count) is large.
  4098 #define RANDOMIZED_DOMAIN_POW 29
  4099 #define RANDOMIZED_DOMAIN (1 << RANDOMIZED_DOMAIN_POW)
  4100 #define RANDOMIZED_DOMAIN_MASK ((1 << (RANDOMIZED_DOMAIN_POW + 1)) - 1)
  4101 bool Compile::randomized_select(int count) {
  4102   assert(count > 0, "only positive");
  4103   return (os::random() & RANDOMIZED_DOMAIN_MASK) < (RANDOMIZED_DOMAIN / count);

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