// Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

#include "vm/precompiler.h"

#include "vm/aot_optimizer.h"
#include "vm/assembler.h"
#include "vm/ast_printer.h"
#include "vm/branch_optimizer.h"
#include "vm/cha.h"
#include "vm/code_generator.h"
#include "vm/code_patcher.h"
#include "vm/compiler.h"
#include "vm/constant_propagator.h"
#include "vm/dart_entry.h"
#include "vm/disassembler.h"
#include "vm/exceptions.h"
#include "vm/flags.h"
#include "vm/flow_graph.h"
#include "vm/flow_graph_allocator.h"
#include "vm/flow_graph_builder.h"
#include "vm/flow_graph_compiler.h"
#include "vm/flow_graph_inliner.h"
#include "vm/flow_graph_range_analysis.h"
#include "vm/flow_graph_type_propagator.h"
#include "vm/hash_table.h"
#include "vm/il_printer.h"
#include "vm/isolate.h"
#include "vm/log.h"
#include "vm/longjump.h"
#include "vm/object.h"
#include "vm/object_store.h"
#include "vm/os.h"
#include "vm/parser.h"
#include "vm/redundancy_elimination.h"
#include "vm/regexp_assembler.h"
#include "vm/regexp_parser.h"
#include "vm/resolver.h"
#include "vm/symbols.h"
#include "vm/tags.h"
#include "vm/timeline.h"
#include "vm/timer.h"
#include "vm/type_table.h"

namespace dart {


#define T (thread())
#define I (isolate())
#define Z (zone())


DEFINE_FLAG(bool, print_unique_targets, false, "Print unique dynaic targets");
DEFINE_FLAG(bool, trace_precompiler, false, "Trace precompiler.");
DEFINE_FLAG(int, max_speculative_inlining_attempts, 1,
    "Max number of attempts with speculative inlining (precompilation only)");
DEFINE_FLAG(int, precompiler_rounds, 1, "Number of precompiler iterations");

DECLARE_FLAG(bool, allocation_sinking);
DECLARE_FLAG(bool, common_subexpression_elimination);
DECLARE_FLAG(bool, constant_propagation);
DECLARE_FLAG(bool, loop_invariant_code_motion);
DECLARE_FLAG(bool, print_flow_graph);
DECLARE_FLAG(bool, print_flow_graph_optimized);
DECLARE_FLAG(bool, range_analysis);
DECLARE_FLAG(bool, trace_compiler);
DECLARE_FLAG(bool, trace_optimizing_compiler);
DECLARE_FLAG(bool, trace_bailout);
DECLARE_FLAG(bool, use_inlining);
DECLARE_FLAG(bool, verify_compiler);
DECLARE_FLAG(bool, huge_method_cutoff_in_code_size);
DECLARE_FLAG(bool, trace_failed_optimization_attempts);
DECLARE_FLAG(bool, trace_inlining_intervals);
DECLARE_FLAG(bool, trace_irregexp);

#ifdef DART_PRECOMPILER

class DartPrecompilationPipeline : public DartCompilationPipeline {
 public:
  explicit DartPrecompilationPipeline(Zone* zone,
                                      FieldTypeMap* field_map = NULL)
      : zone_(zone),
        result_type_(CompileType::None()),
        field_map_(field_map) { }

  virtual void FinalizeCompilation(FlowGraph* flow_graph) {
    if ((field_map_ != NULL )&&
        flow_graph->function().IsGenerativeConstructor()) {
      for (BlockIterator block_it = flow_graph->reverse_postorder_iterator();
           !block_it.Done();
           block_it.Advance()) {
        ForwardInstructionIterator it(block_it.Current());
        for (; !it.Done(); it.Advance()) {
          StoreInstanceFieldInstr* store = it.Current()->AsStoreInstanceField();
          if (store != NULL) {
            if (!store->field().IsNull() && store->field().is_final()) {
              if (FLAG_trace_precompiler && FLAG_support_il_printer) {
                THR_Print("Found store to %s <- %s\n",
                          store->field().ToCString(),
                          store->value()->Type()->ToCString());
              }
              FieldTypePair* entry = field_map_->Lookup(&store->field());
              if (entry == NULL) {
                field_map_->Insert(FieldTypePair(
                    &Field::Handle(zone_, store->field().raw()),  // Re-wrap.
                    store->value()->Type()->ToCid()));
                if (FLAG_trace_precompiler && FLAG_support_il_printer) {
                    THR_Print(" initial type = %s\n",
                              store->value()->Type()->ToCString());
                }
                continue;
              }
              CompileType type = CompileType::FromCid(entry->cid_);
              if (FLAG_trace_precompiler && FLAG_support_il_printer) {
                  THR_Print(" old type = %s\n", type.ToCString());
              }
              type.Union(store->value()->Type());
              if (FLAG_trace_precompiler && FLAG_support_il_printer) {
                  THR_Print(" new type = %s\n", type.ToCString());
              }
              entry->cid_ = type.ToCid();
            }
          }
        }
      }
    }

    CompileType result_type = CompileType::None();
    for (BlockIterator block_it = flow_graph->reverse_postorder_iterator();
         !block_it.Done();
         block_it.Advance()) {
      ForwardInstructionIterator it(block_it.Current());
      for (; !it.Done(); it.Advance()) {
        ReturnInstr* return_instr = it.Current()->AsReturn();
        if (return_instr != NULL) {
          result_type.Union(return_instr->InputAt(0)->Type());
        }
      }
    }
    result_type_ = result_type;
  }

  CompileType result_type() { return result_type_; }

 private:
  Zone* zone_;
  CompileType result_type_;
  FieldTypeMap* field_map_;
};


class PrecompileParsedFunctionHelper : public ValueObject {
 public:
  PrecompileParsedFunctionHelper(Precompiler* precompiler,
                                 ParsedFunction* parsed_function,
                                 bool optimized)
      : precompiler_(precompiler),
        parsed_function_(parsed_function),
        optimized_(optimized),
        thread_(Thread::Current()) {
  }

  bool Compile(CompilationPipeline* pipeline);

 private:
  ParsedFunction* parsed_function() const { return parsed_function_; }
  bool optimized() const { return optimized_; }
  Thread* thread() const { return thread_; }
  Isolate* isolate() const { return thread_->isolate(); }

  void FinalizeCompilation(Assembler* assembler,
                           FlowGraphCompiler* graph_compiler,
                           FlowGraph* flow_graph);

  Precompiler* precompiler_;
  ParsedFunction* parsed_function_;
  const bool optimized_;
  Thread* const thread_;

  DISALLOW_COPY_AND_ASSIGN(PrecompileParsedFunctionHelper);
};


static void Jump(const Error& error) {
  Thread::Current()->long_jump_base()->Jump(1, error);
}


RawError* Precompiler::CompileAll(
    Dart_QualifiedFunctionName embedder_entry_points[],
    bool reset_fields) {
  LongJumpScope jump;
  if (setjmp(*jump.Set()) == 0) {
    Precompiler precompiler(Thread::Current(), reset_fields);
    precompiler.DoCompileAll(embedder_entry_points);
    return Error::null();
  } else {
    Thread* thread = Thread::Current();
    const Error& error = Error::Handle(thread->sticky_error());
    thread->clear_sticky_error();
    return error.raw();
  }
}


bool TypeRangeCache::InstanceOfHasClassRange(const AbstractType& type,
                                             intptr_t* lower_limit,
                                             intptr_t* upper_limit) {
  ASSERT(type.IsFinalized() && !type.IsMalformedOrMalbounded());

  if (!type.IsInstantiated()) return false;
  if (type.IsFunctionType()) return false;

  Zone* zone = thread_->zone();
  const TypeArguments& type_arguments =
      TypeArguments::Handle(zone, type.arguments());
  if (!type_arguments.IsNull() &&
      !type_arguments.IsRaw(0, type_arguments.Length())) return false;


  intptr_t type_cid = type.type_class_id();
  if (lower_limits_[type_cid] == kNotContiguous) return false;
  if (lower_limits_[type_cid] != kNotComputed) {
    *lower_limit = lower_limits_[type_cid];
    *upper_limit = upper_limits_[type_cid];
    return true;
  }


  *lower_limit = -1;
  *upper_limit = -1;
  intptr_t last_matching_cid = -1;

  ClassTable* table = thread_->isolate()->class_table();
  Class& cls = Class::Handle(zone);
  AbstractType& cls_type = AbstractType::Handle(zone);
  for (intptr_t cid = kInstanceCid; cid < table->NumCids(); cid++) {
    if (!table->HasValidClassAt(cid)) continue;
    if (cid == kVoidCid) continue;
    if (cid == kDynamicCid) continue;
    cls = table->At(cid);
    if (cls.is_abstract()) continue;
    if (cls.is_patch()) continue;
    if (cls.IsTopLevel()) continue;

    cls_type = cls.RareType();
    if (cls_type.IsSubtypeOf(type, NULL, NULL, Heap::kOld)) {
      last_matching_cid = cid;
      if (*lower_limit == -1) {
        // Found beginning of range.
        *lower_limit = cid;
      } else if (*upper_limit == -1) {
        // Expanding range.
      } else {
        // Found a second range.
        lower_limits_[type_cid] = kNotContiguous;
        return false;
      }
    } else {
      if (*lower_limit == -1) {
        // Still before range.
      } else if (*upper_limit == -1) {
        // Found end of range.
        *upper_limit = last_matching_cid;
      } else {
        // After range.
      }
    }
  }
  if (*lower_limit == -1) {
    // Not implemented by any concrete class.
    *lower_limit = kIllegalCid;
    *upper_limit = kIllegalCid;
  }

  if (*upper_limit == -1) {
    ASSERT(last_matching_cid != -1);
    *upper_limit = last_matching_cid;
  }

  if (FLAG_trace_precompiler) {
    THR_Print("Type check for %s is cid range [%" Pd ", %" Pd "]\n",
              type.ToCString(), *lower_limit, *upper_limit);
  }

  lower_limits_[type_cid] = *lower_limit;
  upper_limits_[type_cid] = *upper_limit;
  return true;
}


Precompiler::Precompiler(Thread* thread, bool reset_fields) :
    thread_(thread),
    zone_(NULL),
    isolate_(thread->isolate()),
    reset_fields_(reset_fields),
    changed_(false),
    function_count_(0),
    class_count_(0),
    selector_count_(0),
    dropped_function_count_(0),
    dropped_field_count_(0),
    dropped_class_count_(0),
    dropped_typearg_count_(0),
    dropped_type_count_(0),
    dropped_library_count_(0),
    libraries_(GrowableObjectArray::Handle(I->object_store()->libraries())),
    pending_functions_(
        GrowableObjectArray::Handle(GrowableObjectArray::New())),
    sent_selectors_(),
    enqueued_functions_(),
    fields_to_retain_(),
    functions_to_retain_(),
    classes_to_retain_(),
    typeargs_to_retain_(),
    types_to_retain_(),
    consts_to_retain_(),
    field_type_map_(),
    error_(Error::Handle()),
    get_runtime_type_is_unique_(false) {
}


void Precompiler::DoCompileAll(
    Dart_QualifiedFunctionName embedder_entry_points[]) {
  ASSERT(I->compilation_allowed());

  {
    StackZone stack_zone(T);
    zone_ = stack_zone.GetZone();

    { HANDLESCOPE(T);
      // Make sure class hierarchy is stable before compilation so that CHA
      // can be used. Also ensures lookup of entry points won't miss functions
      // because their class hasn't been finalized yet.
      FinalizeAllClasses();

      SortClasses();
      TypeRangeCache trc(T, I->class_table()->NumCids());

      // Precompile static initializers to compute result type information.
      PrecompileStaticInitializers();

      // Precompile constructors to compute type information for final fields.
      ClearAllCode();
      PrecompileConstructors();

      for (intptr_t round = 0; round < FLAG_precompiler_rounds; round++) {
        if (FLAG_trace_precompiler) {
          THR_Print("Precompiler round %" Pd "\n", round);
        }

        if (round > 0) {
          ResetPrecompilerState();
        }

        // TODO(rmacnak): We should be able to do a more thorough job and drop
        // some
        //  - implicit static closures
        //  - field initializers
        //  - invoke-field-dispatchers
        //  - method-extractors
        // that are needed in early iterations but optimized away in later
        // iterations.
        ClearAllCode();

        CollectDynamicFunctionNames();

        // Start with the allocations and invocations that happen from C++.
        AddRoots(embedder_entry_points);

        // Compile newly found targets and add their callees until we reach a
        // fixed point.
        Iterate();
      }

      I->set_compilation_allowed(false);

      TraceForRetainedFunctions();
      DropFunctions();
      DropFields();
      TraceTypesFromRetainedClasses();
      DropTypes();
      DropTypeArguments();

      // Clear these before dropping classes as they may hold onto otherwise
      // dead instances of classes we will remove or otherwise unused symbols.
      DropScriptData();
      I->object_store()->set_unique_dynamic_targets(Array::null_array());
      Class& null_class = Class::Handle(Z);
      I->object_store()->set_future_class(null_class);
      I->object_store()->set_completer_class(null_class);
      I->object_store()->set_stream_iterator_class(null_class);
      I->object_store()->set_symbol_class(null_class);
      I->object_store()->set_compiletime_error_class(null_class);
    }
    DropClasses();
    DropLibraries();

    BindStaticCalls();
    SwitchICCalls();

    ShareMegamorphicBuckets();
    DedupStackmaps();
    DedupLists();

    if (FLAG_dedup_instructions) {
      // Reduces binary size but obfuscates profiler results.
      DedupInstructions();
    }

    zone_ = NULL;
  }

  intptr_t symbols_before = -1;
  intptr_t symbols_after = -1;
  intptr_t capacity = -1;
  if (FLAG_trace_precompiler) {
    Symbols::GetStats(I, &symbols_before, &capacity);
  }

  Symbols::Compact(I);

  if (FLAG_trace_precompiler) {
    Symbols::GetStats(I, &symbols_after, &capacity);
    THR_Print("Precompiled %" Pd " functions,", function_count_);
    THR_Print(" %" Pd " dynamic types,", class_count_);
    THR_Print(" %" Pd " dynamic selectors.\n", selector_count_);

    THR_Print("Dropped %" Pd " functions,", dropped_function_count_);
    THR_Print(" %" Pd " fields,", dropped_field_count_);
    THR_Print(" %" Pd " symbols,", symbols_before - symbols_after);
    THR_Print(" %" Pd " types,", dropped_type_count_);
    THR_Print(" %" Pd " type arguments,", dropped_typearg_count_);
    THR_Print(" %" Pd " classes,", dropped_class_count_);
    THR_Print(" %" Pd " libraries.\n", dropped_library_count_);
  }
}


static void CompileStaticInitializerIgnoreErrors(const Field& field) {
  LongJumpScope jump;
  if (setjmp(*jump.Set()) == 0) {
    Precompiler::CompileStaticInitializer(field, /* compute_type = */ true);
  } else {
    // Ignore compile-time errors here. If the field is actually used,
    // the error will be reported later during Iterate().
  }
}


void Precompiler::PrecompileStaticInitializers() {
  class StaticInitializerVisitor : public ClassVisitor {
   public:
    explicit StaticInitializerVisitor(Zone* zone)
      : fields_(Array::Handle(zone)),
        field_(Field::Handle(zone)),
        function_(Function::Handle(zone)) { }
    void Visit(const Class& cls) {
      fields_ = cls.fields();
      for (intptr_t j = 0; j < fields_.Length(); j++) {
        field_ ^= fields_.At(j);
        if (field_.is_static() &&
            field_.is_final() &&
            field_.has_initializer()) {
          if (FLAG_trace_precompiler) {
            THR_Print("Precompiling initializer for %s\n", field_.ToCString());
          }
          CompileStaticInitializerIgnoreErrors(field_);
        }
      }
    }

   private:
    Array& fields_;
    Field& field_;
    Function& function_;
  };

  HANDLESCOPE(T);
  StaticInitializerVisitor visitor(Z);
  VisitClasses(&visitor);
}


void Precompiler::PrecompileConstructors() {
  class ConstructorVisitor : public FunctionVisitor {
   public:
    explicit ConstructorVisitor(Precompiler* precompiler, Zone* zone)
        : precompiler_(precompiler), zone_(zone) {
    }
    void Visit(const Function& function) {
      if (!function.IsGenerativeConstructor()) return;
      if (function.HasCode()) {
        // Const constructors may have been visited before. Recompile them here
        // to collect type information for final fields for them as well.
        function.ClearCode();
      }
      if (FLAG_trace_precompiler) {
        THR_Print("Precompiling constructor %s\n", function.ToCString());
      }
      CompileFunction(precompiler_,
                      Thread::Current(),
                      zone_,
                      function,
                      precompiler_->field_type_map());
    }

   private:
    Precompiler* precompiler_;
    Zone* zone_;
  };

  HANDLESCOPE(T);
  ConstructorVisitor visitor(this, zone_);
  VisitFunctions(&visitor);

  FieldTypeMap::Iterator it(field_type_map_.GetIterator());
  for (FieldTypePair* current = it.Next();
       current != NULL;
       current = it.Next()) {
    const intptr_t cid = current->cid_;
    current->field_->set_guarded_cid(cid);
    current->field_->set_is_nullable(cid == kNullCid || cid == kDynamicCid);
    if (FLAG_trace_precompiler) {
      THR_Print("Field %s <- Type %s\n", current->field_->ToCString(),
          Class::Handle(T->isolate()->class_table()->At(cid)).ToCString());
    }
  }
}


void Precompiler::ClearAllCode() {
  class ClearCodeFunctionVisitor : public FunctionVisitor {
    void Visit(const Function& function) {
      function.ClearCode();
      function.ClearICDataArray();
    }
  };
  ClearCodeFunctionVisitor function_visitor;
  VisitFunctions(&function_visitor);

  class ClearCodeClassVisitor : public ClassVisitor {
    void Visit(const Class& cls) {
      cls.DisableAllocationStub();
    }
  };
  ClearCodeClassVisitor class_visitor;
  VisitClasses(&class_visitor);
}


void Precompiler::AddRoots(Dart_QualifiedFunctionName embedder_entry_points[]) {
  // Note that <rootlibrary>.main is not a root. The appropriate main will be
  // discovered through _getMainClosure.

  AddSelector(Symbols::NoSuchMethod());

  AddSelector(Symbols::Call());  // For speed, not correctness.

  // Allocated from C++.
  Class& cls = Class::Handle(Z);
  for (intptr_t cid = kInstanceCid; cid < kNumPredefinedCids; cid++) {
    ASSERT(isolate()->class_table()->IsValidIndex(cid));
    if (!isolate()->class_table()->HasValidClassAt(cid)) {
      continue;
    }
    if ((cid == kDynamicCid) ||
        (cid == kVoidCid) ||
        (cid == kFreeListElement) ||
        (cid == kForwardingCorpse)) {
      continue;
    }
    cls = isolate()->class_table()->At(cid);
    AddInstantiatedClass(cls);
  }

  Dart_QualifiedFunctionName vm_entry_points[] = {
    // Functions
    { "dart:async", "::", "_setScheduleImmediateClosure" },
    { "dart:core", "::", "_completeDeferredLoads" },
    { "dart:core", "AbstractClassInstantiationError",
                   "AbstractClassInstantiationError._create" },
    { "dart:core", "ArgumentError", "ArgumentError." },
    { "dart:core", "CyclicInitializationError",
                   "CyclicInitializationError." },
    { "dart:core", "FallThroughError", "FallThroughError._create" },
    { "dart:core", "FormatException", "FormatException." },
    { "dart:core", "NoSuchMethodError", "NoSuchMethodError._withType" },
    { "dart:core", "NullThrownError", "NullThrownError." },
    { "dart:core", "OutOfMemoryError", "OutOfMemoryError." },
    { "dart:core", "RangeError", "RangeError." },
    { "dart:core", "RangeError", "RangeError.range" },
    { "dart:core", "StackOverflowError", "StackOverflowError." },
    { "dart:core", "UnsupportedError", "UnsupportedError." },
    { "dart:core", "_AssertionError", "_AssertionError._create" },
    { "dart:core", "_CastError", "_CastError._create" },
    { "dart:core", "_InternalError", "_InternalError." },
    { "dart:core", "_InvocationMirror", "_allocateInvocationMirror" },
    { "dart:core", "_TypeError", "_TypeError._create" },
    { "dart:isolate", "IsolateSpawnException", "IsolateSpawnException." },
    { "dart:isolate", "::", "_getIsolateScheduleImmediateClosure" },
    { "dart:isolate", "::", "_setupHooks" },
    { "dart:isolate", "::", "_startMainIsolate" },
    { "dart:isolate", "::", "_startIsolate" },
    { "dart:isolate", "_RawReceivePortImpl", "_handleMessage" },
    { "dart:isolate", "_RawReceivePortImpl", "_lookupHandler" },
    { "dart:isolate", "_SendPortImpl", "send" },
    { "dart:typed_data", "ByteData", "ByteData." },
    { "dart:typed_data", "ByteData", "ByteData._view" },
    { "dart:typed_data", "ByteBuffer", "ByteBuffer._New" },
    { "dart:_vmservice", "::", "_registerIsolate" },
    { "dart:_vmservice", "::", "boot" },
#if !defined(PRODUCT)
    { "dart:developer", "Metrics", "_printMetrics" },
    { "dart:developer", "::", "_runExtension" },
    { "dart:isolate", "::", "_runPendingImmediateCallback" },
#endif  // !PRODUCT
    // Fields
    { "dart:core", "Error", "_stackTrace" },
    { "dart:math", "_Random", "_state" },
    { NULL, NULL, NULL }  // Must be terminated with NULL entries.
  };

  AddEntryPoints(vm_entry_points);
  AddEntryPoints(embedder_entry_points);
}


void Precompiler::AddEntryPoints(Dart_QualifiedFunctionName entry_points[]) {
  Library& lib = Library::Handle(Z);
  Class& cls = Class::Handle(Z);
  Function& func = Function::Handle(Z);
  Field& field = Field::Handle(Z);
  String& library_uri = String::Handle(Z);
  String& class_name = String::Handle(Z);
  String& function_name = String::Handle(Z);

  for (intptr_t i = 0; entry_points[i].library_uri != NULL; i++) {
    library_uri = Symbols::New(thread(), entry_points[i].library_uri);
    class_name = Symbols::New(thread(), entry_points[i].class_name);
    function_name = Symbols::New(thread(), entry_points[i].function_name);

    lib = Library::LookupLibrary(T, library_uri);
    if (lib.IsNull()) {
      String& msg = String::Handle(Z, String::NewFormatted(
          "Cannot find entry point %s\n", entry_points[i].library_uri));
      Jump(Error::Handle(Z, ApiError::New(msg)));
      UNREACHABLE();
    }

    if (class_name.raw() == Symbols::TopLevel().raw()) {
      if (Library::IsPrivate(function_name)) {
        function_name = lib.PrivateName(function_name);
      }
      func = lib.LookupLocalFunction(function_name);
      field = lib.LookupLocalField(function_name);
    } else {
      if (Library::IsPrivate(class_name)) {
        class_name = lib.PrivateName(class_name);
      }
      cls = lib.LookupLocalClass(class_name);
      if (cls.IsNull()) {
        String& msg = String::Handle(Z, String::NewFormatted(
            "Cannot find entry point %s %s\n",
            entry_points[i].library_uri,
            entry_points[i].class_name));
        Jump(Error::Handle(Z, ApiError::New(msg)));
        UNREACHABLE();
      }

      ASSERT(!cls.IsNull());
      func = cls.LookupFunctionAllowPrivate(function_name);
      field = cls.LookupFieldAllowPrivate(function_name);
    }

    if (func.IsNull() && field.IsNull()) {
      String& msg = String::Handle(Z, String::NewFormatted(
          "Cannot find entry point %s %s %s\n",
          entry_points[i].library_uri,
          entry_points[i].class_name,
          entry_points[i].function_name));
      Jump(Error::Handle(Z, ApiError::New(msg)));
      UNREACHABLE();
    }

    if (!func.IsNull()) {
      AddFunction(func);
      if (func.IsGenerativeConstructor()) {
        // Allocation stubs are referenced from the call site of the
        // constructor, not in the constructor itself. So compiling the
        // constructor isn't enough for us to discover the class is
        // instantiated if the class isn't otherwise instantiated from Dart
        // code and only instantiated from C++.
        AddInstantiatedClass(cls);
      }
    }
    if (!field.IsNull()) {
      AddField(field);
    }
  }
}


void Precompiler::Iterate() {
  Function& function = Function::Handle(Z);

  while (changed_) {
    changed_ = false;

    while (pending_functions_.Length() > 0) {
      function ^= pending_functions_.RemoveLast();
      ProcessFunction(function);
    }

    CheckForNewDynamicFunctions();
    if (!changed_) {
      TraceConstFunctions();
    }
    CollectCallbackFields();
  }
}


void Precompiler::CollectCallbackFields() {
  Library& lib = Library::Handle(Z);
  Class& cls = Class::Handle(Z);
  Class& subcls = Class::Handle(Z);
  Array& fields = Array::Handle(Z);
  Field& field = Field::Handle(Z);
  Function& function = Function::Handle(Z);
  Function& dispatcher = Function::Handle(Z);
  Array& args_desc = Array::Handle(Z);
  AbstractType& field_type = AbstractType::Handle(Z);
  String& field_name = String::Handle(Z);
  GrowableArray<intptr_t> cids;

  for (intptr_t i = 0; i < libraries_.Length(); i++) {
    lib ^= libraries_.At(i);
    ClassDictionaryIterator it(lib, ClassDictionaryIterator::kIteratePrivate);
    while (it.HasNext()) {
      cls = it.GetNextClass();

      if (!cls.is_allocated()) continue;

      fields = cls.fields();
      for (intptr_t k = 0; k < fields.Length(); k++) {
        field ^= fields.At(k);
        if (field.is_static()) continue;
        field_type = field.type();
        if (!field_type.IsFunctionType()) continue;
        field_name = field.name();
        if (!IsSent(field_name)) continue;
        // Create arguments descriptor with fixed parameters from
        // signature of field_type.
        function = Type::Cast(field_type).signature();
        if (function.HasOptionalParameters()) continue;
        if (FLAG_trace_precompiler) {
          THR_Print("Found callback field %s\n", field_name.ToCString());
        }
        args_desc =
            ArgumentsDescriptor::New(function.num_fixed_parameters());
        cids.Clear();
        if (T->cha()->ConcreteSubclasses(cls, &cids)) {
          for (intptr_t j = 0; j < cids.length(); ++j) {
            subcls ^= I->class_table()->At(cids[j]);
            if (subcls.is_allocated()) {
              // Add dispatcher to cls.
              dispatcher = subcls.GetInvocationDispatcher(
                  field_name,
                  args_desc,
                  RawFunction::kInvokeFieldDispatcher,
                  /* create_if_absent = */ true);
              if (FLAG_trace_precompiler) {
                THR_Print("Added invoke-field-dispatcher for %s to %s\n",
                          field_name.ToCString(), subcls.ToCString());
              }
              AddFunction(dispatcher);
            }
          }
        }
      }
    }
  }
}


void Precompiler::ProcessFunction(const Function& function) {
  if (!function.HasCode()) {
    function_count_++;

    if (FLAG_trace_precompiler) {
      THR_Print("Precompiling %" Pd " %s (%s, %s)\n",
                function_count_,
                function.ToLibNamePrefixedQualifiedCString(),
                function.token_pos().ToCString(),
                Function::KindToCString(function.kind()));
    }

    ASSERT(!function.is_abstract());
    ASSERT(!function.IsRedirectingFactory());

    error_ = CompileFunction(this, thread_, zone_, function);
    if (!error_.IsNull()) {
      Jump(error_);
    }
    // Used in the JIT to save type-feedback across compilations.
    function.ClearICDataArray();
  } else {
    if (FLAG_trace_precompiler) {
      // This function was compiled from somewhere other than Precompiler,
      // such as const constructors compiled by the parser.
      THR_Print("Already has code: %s (%s, %s)\n",
                function.ToLibNamePrefixedQualifiedCString(),
                function.token_pos().ToCString(),
                Function::KindToCString(function.kind()));
    }
  }

  ASSERT(function.HasCode());
  AddCalleesOf(function);
}


void Precompiler::AddCalleesOf(const Function& function) {
  ASSERT(function.HasCode());

  const Code& code = Code::Handle(Z, function.CurrentCode());

  const Array& table = Array::Handle(Z, code.static_calls_target_table());
  Object& entry = Object::Handle(Z);
  Function& target = Function::Handle(Z);
  for (intptr_t i = 0; i < table.Length(); i++) {
    entry = table.At(i);
    if (entry.IsFunction()) {
      target ^= entry.raw();
      AddFunction(target);
    }
  }

#if defined(TARGET_ARCH_IA32)
  FATAL("Callee scanning unimplemented for IA32");
#endif

  const ObjectPool& pool = ObjectPool::Handle(Z, code.GetObjectPool());
  ICData& call_site = ICData::Handle(Z);
  MegamorphicCache& cache = MegamorphicCache::Handle(Z);
  String& selector = String::Handle(Z);
  Field& field = Field::Handle(Z);
  Class& cls = Class::Handle(Z);
  Instance& instance = Instance::Handle(Z);
  Code& target_code = Code::Handle(Z);
  for (intptr_t i = 0; i < pool.Length(); i++) {
    if (pool.InfoAt(i) == ObjectPool::kTaggedObject) {
      entry = pool.ObjectAt(i);
      if (entry.IsICData()) {
        call_site ^= entry.raw();
        for (intptr_t j = 0; j < call_site.NumberOfChecks(); j++) {
          target = call_site.GetTargetAt(j);
          AddFunction(target);
          if (!target.is_static()) {
            // Super call (should not enqueue selector) or dynamic call with a
            // CHA prediction (should enqueue selector).
            selector = call_site.target_name();
            AddSelector(selector);
          }
        }
        if (call_site.NumberOfChecks() == 0) {
          // A dynamic call.
          selector = call_site.target_name();
          AddSelector(selector);
          if (selector.raw() == Symbols::Call().raw()) {
            // Potential closure call.
            AddClosureCall(call_site);
          }
        }
      } else if (entry.IsMegamorphicCache()) {
        // A dynamic call.
        cache ^= entry.raw();
        selector = cache.target_name();
        AddSelector(selector);
      } else if (entry.IsField()) {
        // Potential need for field initializer.
        field ^= entry.raw();
        AddField(field);
      } else if (entry.IsInstance()) {
        // Const object, literal or args descriptor.
        instance ^= entry.raw();
        if (entry.IsAbstractType()) {
          AddType(AbstractType::Cast(entry));
        } else {
          AddConstObject(instance);
        }
      } else if (entry.IsFunction()) {
        // Local closure function.
        target ^= entry.raw();
        AddFunction(target);
      } else if (entry.IsCode()) {
        target_code ^= entry.raw();
        if (target_code.IsAllocationStubCode()) {
          cls ^= target_code.owner();
          AddInstantiatedClass(cls);
        }
      } else if (entry.IsTypeArguments()) {
        AddTypeArguments(TypeArguments::Cast(entry));
      }
    }
  }
}


void Precompiler::AddTypesOf(const Class& cls) {
  if (cls.IsNull()) return;
  if (classes_to_retain_.Lookup(&cls) != NULL) return;
  classes_to_retain_.Insert(&Class::ZoneHandle(Z, cls.raw()));

  Array& interfaces = Array::Handle(Z, cls.interfaces());
  AbstractType& type = AbstractType::Handle(Z);
  for (intptr_t i = 0; i < interfaces.Length(); i++) {
    type ^= interfaces.At(i);
    AddType(type);
  }

  AddTypeArguments(TypeArguments::Handle(Z, cls.type_parameters()));

  type = cls.super_type();
  AddType(type);

  type = cls.mixin();
  AddType(type);

  if (cls.IsTypedefClass()) {
    AddTypesOf(Function::Handle(Z, cls.signature_function()));
  }
}


void Precompiler::AddTypesOf(const Function& function) {
  if (function.IsNull()) return;
  if (functions_to_retain_.Lookup(&function) != NULL) return;
  functions_to_retain_.Insert(&Function::ZoneHandle(Z, function.raw()));

  AbstractType& type = AbstractType::Handle(Z);
  type = function.result_type();
  AddType(type);
  for (intptr_t i = 0; i < function.NumParameters(); i++) {
    type = function.ParameterTypeAt(i);
    AddType(type);
  }
  Code& code = Code::Handle(Z, function.CurrentCode());
  if (code.IsNull()) {
    ASSERT(function.kind() == RawFunction::kSignatureFunction);
  } else {
    const ExceptionHandlers& handlers =
        ExceptionHandlers::Handle(Z, code.exception_handlers());
    if (!handlers.IsNull()) {
      Array& types = Array::Handle(Z);
      for (intptr_t i = 0; i < handlers.num_entries(); i++) {
        types = handlers.GetHandledTypes(i);
        for (intptr_t j = 0; j < types.Length(); j++) {
          type ^= types.At(j);
          AddType(type);
        }
      }
    }
  }
  // A function can always be inlined and have only a nested local function
  // remain.
  const Function& parent = Function::Handle(Z, function.parent_function());
  if (!parent.IsNull()) {
    AddTypesOf(parent);
  }
  // A class may have all functions inlined except a local function.
  const Class& owner = Class::Handle(Z, function.Owner());
  AddTypesOf(owner);
}


void Precompiler::AddType(const AbstractType& abstype) {
  if (abstype.IsNull()) return;

  if (types_to_retain_.Lookup(&abstype) != NULL) return;
  types_to_retain_.Insert(&AbstractType::ZoneHandle(Z, abstype.raw()));

  if (abstype.IsType()) {
    const Type& type = Type::Cast(abstype);
    const Class& cls = Class::Handle(Z, type.type_class());
    AddTypesOf(cls);
    const TypeArguments& vector = TypeArguments::Handle(Z, abstype.arguments());
    AddTypeArguments(vector);
    if (type.IsFunctionType()) {
      const Function& func = Function::Handle(Z, type.signature());
      AddTypesOf(func);
    }
  } else if (abstype.IsBoundedType()) {
    AbstractType& type = AbstractType::Handle(Z);
    type = BoundedType::Cast(abstype).type();
    AddType(type);
    type = BoundedType::Cast(abstype).bound();
    AddType(type);
  } else if (abstype.IsTypeRef()) {
    AbstractType& type = AbstractType::Handle(Z);
    type = TypeRef::Cast(abstype).type();
    AddType(type);
  } else if (abstype.IsTypeParameter()) {
    const AbstractType& type =
        AbstractType::Handle(Z, TypeParameter::Cast(abstype).bound());
    AddType(type);
    const Class& cls =
        Class::Handle(Z, TypeParameter::Cast(abstype).parameterized_class());
    AddTypesOf(cls);
  }
}


void Precompiler::AddTypeArguments(const TypeArguments& args) {
  if (args.IsNull()) return;

  if (typeargs_to_retain_.Lookup(&args) != NULL) return;
  typeargs_to_retain_.Insert(&TypeArguments::ZoneHandle(Z, args.raw()));

  AbstractType& arg = AbstractType::Handle(Z);
  for (intptr_t i = 0; i < args.Length(); i++) {
    arg = args.TypeAt(i);
    AddType(arg);
  }
}


void Precompiler::AddConstObject(const Instance& instance) {
  const Class& cls = Class::Handle(Z, instance.clazz());
  AddInstantiatedClass(cls);

  if (instance.IsClosure()) {
    // An implicit static closure.
    const Function& func =
        Function::Handle(Z, Closure::Cast(instance).function());
    ASSERT(func.is_static());
    AddFunction(func);
    AddTypeArguments(TypeArguments::Handle(Z, instance.GetTypeArguments()));
    return;
  }

  // Can't ask immediate objects if they're canoncial.
  if (instance.IsSmi()) return;

  // Some Instances in the ObjectPool aren't const objects, such as
  // argument descriptors.
  if (!instance.IsCanonical()) return;

  consts_to_retain_.Insert(&Instance::ZoneHandle(Z, instance.raw()));

  if (cls.NumTypeArguments() > 0) {
    AddTypeArguments(TypeArguments::Handle(Z, instance.GetTypeArguments()));
  }

  class ConstObjectVisitor : public ObjectPointerVisitor {
   public:
    ConstObjectVisitor(Precompiler* precompiler, Isolate* isolate) :
        ObjectPointerVisitor(isolate),
        precompiler_(precompiler),
        subinstance_(Object::Handle()) {}

    virtual void VisitPointers(RawObject** first, RawObject** last) {
      for (RawObject** current = first; current <= last; current++) {
        subinstance_ = *current;
        if (subinstance_.IsInstance()) {
          precompiler_->AddConstObject(Instance::Cast(subinstance_));
        }
      }
      subinstance_ = Object::null();
    }

   private:
    Precompiler* precompiler_;
    Object& subinstance_;
  };

  ConstObjectVisitor visitor(this, I);
  instance.raw()->VisitPointers(&visitor);
}


void Precompiler::AddClosureCall(const ICData& call_site) {
  const Array& arguments_descriptor =
      Array::Handle(Z, call_site.arguments_descriptor());
  const Class& cache_class =
      Class::Handle(Z, I->object_store()->closure_class());
  const Function& dispatcher = Function::Handle(Z,
      cache_class.GetInvocationDispatcher(Symbols::Call(),
                                          arguments_descriptor,
                                          RawFunction::kInvokeFieldDispatcher,
                                          true /* create_if_absent */));
  AddFunction(dispatcher);
}


void Precompiler::AddField(const Field& field) {
  fields_to_retain_.Insert(&Field::ZoneHandle(Z, field.raw()));

  if (field.is_static()) {
    const Object& value = Object::Handle(Z, field.StaticValue());
    if (value.IsInstance()) {
      AddConstObject(Instance::Cast(value));
    }

    if (field.has_initializer()) {
      // Should not be in the middle of initialization while precompiling.
      ASSERT(value.raw() != Object::transition_sentinel().raw());

      const bool is_initialized = value.raw() != Object::sentinel().raw();
      if (is_initialized && !reset_fields_) return;

      if (!field.HasPrecompiledInitializer() ||
          !Function::Handle(Z, field.PrecompiledInitializer()).HasCode()) {
        if (FLAG_trace_precompiler) {
          THR_Print("Precompiling initializer for %s\n", field.ToCString());
        }
        ASSERT(Dart::snapshot_kind() != Snapshot::kAppNoJIT);
        const Function& initializer = Function::Handle(Z,
            CompileStaticInitializer(field, /* compute_type = */ true));
        ASSERT(!initializer.IsNull());
        field.SetPrecompiledInitializer(initializer);
        AddCalleesOf(initializer);
      }
    }
  }
}


RawFunction* Precompiler::CompileStaticInitializer(const Field& field,
                                                   bool compute_type) {
  ASSERT(field.is_static());
  Thread* thread = Thread::Current();
  StackZone zone(thread);

  ParsedFunction* parsed_function = Parser::ParseStaticFieldInitializer(field);

  parsed_function->AllocateVariables();
  DartPrecompilationPipeline pipeline(zone.GetZone());
  PrecompileParsedFunctionHelper helper(/* precompiler = */ NULL,
                                        parsed_function,
                                        /* optimized = */ true);
  bool success = helper.Compile(&pipeline);
  ASSERT(success);

  if (compute_type && field.is_final()) {
    intptr_t result_cid = pipeline.result_type().ToCid();
    if (result_cid != kDynamicCid) {
      if (FLAG_trace_precompiler && FLAG_support_il_printer) {
        THR_Print("Setting guarded_cid of %s to %s\n", field.ToCString(),
                  pipeline.result_type().ToCString());
      }
      field.set_guarded_cid(result_cid);
    }
  }

  if ((FLAG_disassemble || FLAG_disassemble_optimized) &&
      FlowGraphPrinter::ShouldPrint(parsed_function->function())) {
    Disassembler::DisassembleCode(parsed_function->function(),
                                  /* optimized = */ true);
  }
  return parsed_function->function().raw();
}


RawObject* Precompiler::EvaluateStaticInitializer(const Field& field) {
  ASSERT(field.is_static());
  // The VM sets the field's value to transiton_sentinel prior to
  // evaluating the initializer value.
  ASSERT(field.StaticValue() == Object::transition_sentinel().raw());
  LongJumpScope jump;
  if (setjmp(*jump.Set()) == 0) {
    // Under precompilation, the initializer may have already been compiled, in
    // which case use it. Under lazy compilation or early in precompilation, the
    // initializer has not yet been created, so create it now, but don't bother
    // remembering it because it won't be used again.
    Function& initializer = Function::Handle();
    if (!field.HasPrecompiledInitializer()) {
      initializer = CompileStaticInitializer(field, /* compute_type = */ false);
    } else {
      initializer ^= field.PrecompiledInitializer();
    }
    // Invoke the function to evaluate the expression.
    return DartEntry::InvokeFunction(initializer, Object::empty_array());
  } else {
    Thread* const thread = Thread::Current();
    StackZone zone(thread);
    const Error& error =
        Error::Handle(thread->zone(), thread->sticky_error());
    thread->clear_sticky_error();
    return error.raw();
  }
  UNREACHABLE();
  return Object::null();
}


RawObject* Precompiler::ExecuteOnce(SequenceNode* fragment) {
  LongJumpScope jump;
  if (setjmp(*jump.Set()) == 0) {
    Thread* const thread = Thread::Current();
    if (FLAG_support_ast_printer && FLAG_trace_compiler) {
      THR_Print("compiling expression: ");
      AstPrinter ast_printer;
      ast_printer.PrintNode(fragment);
    }

    // Create a dummy function object for the code generator.
    // The function needs to be associated with a named Class: the interface
    // Function fits the bill.
    const char* kEvalConst = "eval_const";
    const Function& func = Function::ZoneHandle(Function::New(
        String::Handle(Symbols::New(thread, kEvalConst)),
        RawFunction::kRegularFunction,
        true,  // static function
        false,  // not const function
        false,  // not abstract
        false,  // not external
        false,  // not native
        Class::Handle(Type::Handle(Type::DartFunctionType()).type_class()),
        fragment->token_pos()));

    func.set_result_type(Object::dynamic_type());
    func.set_num_fixed_parameters(0);
    func.SetNumOptionalParameters(0, true);
    // Manually generated AST, do not recompile.
    func.SetIsOptimizable(false);
    func.set_is_debuggable(false);

    // We compile the function here, even though InvokeFunction() below
    // would compile func automatically. We are checking fewer invariants
    // here.
    ParsedFunction* parsed_function = new ParsedFunction(thread, func);
    parsed_function->SetNodeSequence(fragment);
    fragment->scope()->AddVariable(parsed_function->EnsureExpressionTemp());
    fragment->scope()->AddVariable(
        parsed_function->current_context_var());
    parsed_function->AllocateVariables();

    // Non-optimized code generator.
    DartPrecompilationPipeline pipeline(Thread::Current()->zone());
    PrecompileParsedFunctionHelper helper(/* precompiler = */ NULL,
                                          parsed_function,
                                          /* optimized = */ false);
    helper.Compile(&pipeline);
    Code::Handle(func.unoptimized_code()).set_var_descriptors(
        Object::empty_var_descriptors());

    const Object& result = PassiveObject::Handle(
        DartEntry::InvokeFunction(func, Object::empty_array()));
    return result.raw();
  } else {
    Thread* const thread = Thread::Current();
    const Object& result =
      PassiveObject::Handle(thread->sticky_error());
    thread->clear_sticky_error();
    return result.raw();
  }
  UNREACHABLE();
  return Object::null();
}


void Precompiler::AddFunction(const Function& function) {
  if (enqueued_functions_.Lookup(&function) != NULL) return;

  enqueued_functions_.Insert(&Function::ZoneHandle(Z, function.raw()));
  pending_functions_.Add(function);
  changed_ = true;
}


bool Precompiler::IsSent(const String& selector) {
  if (selector.IsNull()) {
    return false;
  }
  return sent_selectors_.Lookup(&selector) != NULL;
}


void Precompiler::AddSelector(const String& selector) {
  ASSERT(!selector.IsNull());

  if (!IsSent(selector)) {
    sent_selectors_.Insert(&String::ZoneHandle(Z, selector.raw()));
    selector_count_++;
    changed_ = true;

    if (FLAG_trace_precompiler) {
      THR_Print("Enqueueing selector %" Pd " %s\n",
                selector_count_,
                selector.ToCString());
    }
  }
}


void Precompiler::AddInstantiatedClass(const Class& cls) {
  if (cls.is_allocated()) return;

  class_count_++;
  cls.set_is_allocated(true);
  error_ = cls.EnsureIsFinalized(T);
  if (!error_.IsNull()) {
    Jump(error_);
  }

  changed_ = true;

  if (FLAG_trace_precompiler) {
    THR_Print("Allocation %" Pd " %s\n", class_count_, cls.ToCString());
  }

  const Class& superclass = Class::Handle(cls.SuperClass());
  if (!superclass.IsNull()) {
    AddInstantiatedClass(superclass);
  }
}


void Precompiler::CheckForNewDynamicFunctions() {
  Library& lib = Library::Handle(Z);
  Class& cls = Class::Handle(Z);
  Array& functions = Array::Handle(Z);
  Function& function = Function::Handle(Z);
  Function& function2 = Function::Handle(Z);
  String& selector = String::Handle(Z);
  String& selector2 = String::Handle(Z);
  String& selector3 = String::Handle(Z);

  for (intptr_t i = 0; i < libraries_.Length(); i++) {
    lib ^= libraries_.At(i);
    ClassDictionaryIterator it(lib, ClassDictionaryIterator::kIteratePrivate);
    while (it.HasNext()) {
      cls = it.GetNextClass();

      if (!cls.is_allocated()) continue;

      functions = cls.functions();
      for (intptr_t k = 0; k < functions.Length(); k++) {
        function ^= functions.At(k);

        if (function.is_static() || function.is_abstract()) continue;

        // Don't bail out early if there is already code because we may discover
        // the corresponding getter selector is sent in some later iteration.
        // if (function.HasCode()) continue;

        selector = function.name();
        if (IsSent(selector)) {
          AddFunction(function);
        }

        // Handle the implicit call type conversions.
        if (Field::IsGetterName(selector)) {
          selector2 = Field::NameFromGetter(selector);
          selector3 = Symbols::Lookup(thread(), selector2);
          if (IsSent(selector2)) {
            // Call-through-getter.
            // Function is get:foo and somewhere foo is called.
            AddFunction(function);
          }
          selector3 = Symbols::LookupFromConcat(thread(),
              Symbols::ClosurizePrefix(), selector2);
          if (IsSent(selector3)) {
            // Hash-closurization.
            // Function is get:foo and somewhere get:#foo is called.
            AddFunction(function);

            function2 = function.ImplicitClosureFunction();
            AddFunction(function2);

            // Add corresponding method extractor get:#foo.
            function2 = function.GetMethodExtractor(selector3);
            AddFunction(function2);
          }
        } else if (Field::IsSetterName(selector)) {
          selector2 = Symbols::LookupFromConcat(thread(),
              Symbols::ClosurizePrefix(), selector);
          if (IsSent(selector2)) {
            // Hash-closurization.
            // Function is set:foo and somewhere get:#set:foo is called.
            AddFunction(function);

            function2 = function.ImplicitClosureFunction();
            AddFunction(function2);

            // Add corresponding method extractor get:#set:foo.
            function2 = function.GetMethodExtractor(selector2);
            AddFunction(function2);
          }
        } else if (function.kind() == RawFunction::kRegularFunction) {
          selector2 = Field::LookupGetterSymbol(selector);
          if (IsSent(selector2)) {
            // Closurization.
            // Function is foo and somewhere get:foo is called.
            function2 = function.ImplicitClosureFunction();
            AddFunction(function2);

            // Add corresponding method extractor.
            function2 = function.GetMethodExtractor(selector2);
            AddFunction(function2);
          }
          selector2 = Symbols::LookupFromConcat(thread(),
              Symbols::ClosurizePrefix(), selector);
          if (IsSent(selector2)) {
            // Hash-closurization.
            // Function is foo and somewhere get:#foo is called.
            function2 = function.ImplicitClosureFunction();
            AddFunction(function2);

            // Add corresponding method extractor get:#foo
            function2 = function.GetMethodExtractor(selector2);
            AddFunction(function2);
          }
        }
      }
    }
  }
}


class NameFunctionsTraits {
 public:
  static const char* Name() { return "NameFunctionsTraits"; }
  static bool ReportStats() { return false; }

  static bool IsMatch(const Object& a, const Object& b) {
    return a.IsString() && b.IsString() &&
        String::Cast(a).Equals(String::Cast(b));
  }
  static uword Hash(const Object& obj) {
    return String::Cast(obj).Hash();
  }
  static RawObject* NewKey(const String& str) {
    return str.raw();
  }
};

typedef UnorderedHashMap<NameFunctionsTraits> Table;


static void AddNameToFunctionsTable(Zone* zone,
                                    Table* table,
                                    const String& fname,
                                    const Function& function) {
  Array& farray = Array::Handle(zone);
  farray ^= table->InsertNewOrGetValue(fname, Array::empty_array());
  farray = Array::Grow(farray, farray.Length() + 1);
  farray.SetAt(farray.Length() - 1, function);
  table->UpdateValue(fname, farray);
}


void Precompiler::CollectDynamicFunctionNames() {
  if (!FLAG_collect_dynamic_function_names) {
    return;
  }
  Library& lib = Library::Handle(Z);
  Class& cls = Class::Handle(Z);
  Array& functions = Array::Handle(Z);
  Function& function = Function::Handle(Z);
  String& fname = String::Handle(Z);
  Array& farray = Array::Handle(Z);

  Table table(HashTables::New<Table>(100));
  for (intptr_t i = 0; i < libraries_.Length(); i++) {
    lib ^= libraries_.At(i);
    ClassDictionaryIterator it(lib, ClassDictionaryIterator::kIteratePrivate);
    while (it.HasNext()) {
      cls = it.GetNextClass();
      if (cls.IsDynamicClass()) {
        continue;  // class 'dynamic' is in the read-only VM isolate.
      }
      functions = cls.functions();
      for (intptr_t j = 0; j < functions.Length(); j++) {
        function ^= functions.At(j);
        if (function.IsDynamicFunction()) {
          fname = function.name();
          if (function.IsSetterFunction() ||
              function.IsImplicitSetterFunction()) {
            AddNameToFunctionsTable(zone(), &table, fname, function);
          } else if (function.IsGetterFunction() ||
                     function.IsImplicitGetterFunction()) {
            // Enter both getter and non getter name.
            AddNameToFunctionsTable(zone(), &table, fname, function);
            fname = Field::NameFromGetter(fname);
            AddNameToFunctionsTable(zone(), &table, fname, function);
          } else if (function.IsMethodExtractor()) {
            // Skip. We already add getter names for regular methods below.
            continue;
          } else {
            // Regular function. Enter both getter and non getter name.
            AddNameToFunctionsTable(zone(), &table, fname, function);
            fname = Field::GetterName(fname);
            AddNameToFunctionsTable(zone(), &table, fname, function);
          }
        }
      }
    }
  }

  // Locate all entries with one function only
  Table::Iterator iter(&table);
  String& key = String::Handle(Z);
  UniqueFunctionsSet functions_set(HashTables::New<UniqueFunctionsSet>(20));
  while (iter.MoveNext()) {
    intptr_t curr_key = iter.Current();
    key ^= table.GetKey(curr_key);
    farray ^= table.GetOrNull(key);
    ASSERT(!farray.IsNull());
    if (farray.Length() == 1) {
      function ^= farray.At(0);
      cls = function.Owner();
      functions_set.Insert(function);
    }
  }

  farray ^= table.GetOrNull(Symbols::GetRuntimeType());

  get_runtime_type_is_unique_ = !farray.IsNull() && (farray.Length() == 1);

  if (FLAG_print_unique_targets) {
    UniqueFunctionsSet::Iterator unique_iter(&functions_set);
    while (unique_iter.MoveNext()) {
      intptr_t curr_key = unique_iter.Current();
      function ^= functions_set.GetKey(curr_key);
      THR_Print("* %s\n", function.ToQualifiedCString());
    }
    THR_Print("%" Pd " of %" Pd " dynamic selectors are unique\n",
        functions_set.NumOccupied(), table.NumOccupied());
  }

  isolate()->object_store()->set_unique_dynamic_targets(
      functions_set.Release());
  table.Release();
}


void Precompiler::TraceConstFunctions() {
  // Compilation of const accessors happens outside of the treeshakers
  // queue, so we haven't previously scanned its literal pool.

  Library& lib = Library::Handle(Z);
  Class& cls = Class::Handle(Z);
  Array& functions = Array::Handle(Z);
  Function& function = Function::Handle(Z);

  for (intptr_t i = 0; i < libraries_.Length(); i++) {
    lib ^= libraries_.At(i);
    ClassDictionaryIterator it(lib, ClassDictionaryIterator::kIteratePrivate);
    while (it.HasNext()) {
      cls = it.GetNextClass();
      if (cls.IsDynamicClass()) {
        continue;  // class 'dynamic' is in the read-only VM isolate.
      }

      functions = cls.functions();
      for (intptr_t j = 0; j < functions.Length(); j++) {
        function ^= functions.At(j);
        if (function.is_const() && function.HasCode()) {
          AddCalleesOf(function);
        }
      }
    }
  }
}


void Precompiler::TraceForRetainedFunctions() {
  Library& lib = Library::Handle(Z);
  Class& cls = Class::Handle(Z);
  Array& functions = Array::Handle(Z);
  Function& function = Function::Handle(Z);
  Function& function2 = Function::Handle(Z);
  GrowableObjectArray& closures = GrowableObjectArray::Handle(Z);

  for (intptr_t i = 0; i < libraries_.Length(); i++) {
    lib ^= libraries_.At(i);
    ClassDictionaryIterator it(lib, ClassDictionaryIterator::kIteratePrivate);
    while (it.HasNext()) {
      cls = it.GetNextClass();
      if (cls.IsDynamicClass()) {
        continue;  // class 'dynamic' is in the read-only VM isolate.
      }

      functions = cls.functions();
      for (intptr_t j = 0; j < functions.Length(); j++) {
        function ^= functions.At(j);
        bool retain = enqueued_functions_.Lookup(&function) != NULL;
        if (!retain && function.HasImplicitClosureFunction()) {
          // It can happen that all uses of an implicit closure inline their
          // target function, leaving the target function uncompiled. Keep
          // the target function anyway so we can enumerate it to bind its
          // static calls, etc.
          function2 = function.ImplicitClosureFunction();
          retain = function2.HasCode();
        }
        if (retain) {
          function.DropUncompiledImplicitClosureFunction();
          AddTypesOf(function);
        }
      }
    }
  }

  closures = isolate()->object_store()->closure_functions();
  for (intptr_t j = 0; j < closures.Length(); j++) {
    function ^= closures.At(j);
    bool retain = enqueued_functions_.Lookup(&function) != NULL;
    if (retain) {
      AddTypesOf(function);

      cls = function.Owner();
      AddTypesOf(cls);

      // It can happen that all uses of a function are inlined, leaving
      // a compiled local function with an uncompiled parent. Retain such
      // parents and their enclosing classes and libraries.
      function = function.parent_function();
      while (!function.IsNull()) {
        AddTypesOf(function);
        function = function.parent_function();
      }
    }
  }
}


void Precompiler::DropFunctions() {
  Library& lib = Library::Handle(Z);
  Class& cls = Class::Handle(Z);
  Array& functions = Array::Handle(Z);
  Function& function = Function::Handle(Z);
  GrowableObjectArray& retained_functions = GrowableObjectArray::Handle(Z);
  GrowableObjectArray& closures = GrowableObjectArray::Handle(Z);
  String& name = String::Handle(Z);

  for (intptr_t i = 0; i < libraries_.Length(); i++) {
    lib ^= libraries_.At(i);
    ClassDictionaryIterator it(lib, ClassDictionaryIterator::kIteratePrivate);
    while (it.HasNext()) {
      cls = it.GetNextClass();
      if (cls.IsDynamicClass()) {
        continue;  // class 'dynamic' is in the read-only VM isolate.
      }

      functions = cls.functions();
      retained_functions = GrowableObjectArray::New();
      for (intptr_t j = 0; j < functions.Length(); j++) {
        function ^= functions.At(j);
        bool retain = functions_to_retain_.Lookup(&function) != NULL;
        function.DropUncompiledImplicitClosureFunction();
        if (retain) {
          retained_functions.Add(function);
        } else {
          bool top_level = cls.IsTopLevel();
          if (top_level &&
              (function.kind() != RawFunction::kImplicitStaticFinalGetter)) {
            // Implicit static final getters are not added to the library
            // dictionary in the first place.
            name = function.DictionaryName();
            bool removed = lib.RemoveObject(function, name);
            ASSERT(removed);
          }
          dropped_function_count_++;
          if (FLAG_trace_precompiler) {
            THR_Print("Dropping function %s\n",
                      function.ToLibNamePrefixedQualifiedCString());
          }
        }
      }

      if (retained_functions.Length() > 0) {
        functions = Array::MakeArray(retained_functions);
        cls.SetFunctions(functions);
      } else {
        cls.SetFunctions(Object::empty_array());
      }
    }
  }

  closures = isolate()->object_store()->closure_functions();
  retained_functions = GrowableObjectArray::New();
  for (intptr_t j = 0; j < closures.Length(); j++) {
    function ^= closures.At(j);
    bool retain = functions_to_retain_.Lookup(&function) != NULL;
    if (retain) {
      retained_functions.Add(function);
    } else {
      dropped_function_count_++;
      if (FLAG_trace_precompiler) {
        THR_Print("Dropping function %s\n",
                  function.ToLibNamePrefixedQualifiedCString());
      }
    }
  }
  isolate()->object_store()->set_closure_functions(retained_functions);
}


void Precompiler::DropFields() {
  Library& lib = Library::Handle(Z);
  Class& cls = Class::Handle(Z);
  Array& fields = Array::Handle(Z);
  Field& field = Field::Handle(Z);
  GrowableObjectArray& retained_fields = GrowableObjectArray::Handle(Z);
  String& name = String::Handle(Z);
  AbstractType& type = AbstractType::Handle(Z);

  for (intptr_t i = 0; i < libraries_.Length(); i++) {
    lib ^= libraries_.At(i);
    ClassDictionaryIterator it(lib, ClassDictionaryIterator::kIteratePrivate);
    while (it.HasNext()) {
      cls = it.GetNextClass();
      if (cls.IsDynamicClass()) {
        continue;  // class 'dynamic' is in the read-only VM isolate.
      }

      fields = cls.fields();
      retained_fields = GrowableObjectArray::New();
      for (intptr_t j = 0; j < fields.Length(); j++) {
        field ^= fields.At(j);
        bool retain = fields_to_retain_.Lookup(&field) != NULL;
        if (retain) {
          retained_fields.Add(field);
          type = field.type();
          AddType(type);
        } else {
          bool top_level = cls.IsTopLevel();
          if (top_level) {
            name = field.DictionaryName();
            lib.RemoveObject(field, name);
          }
          dropped_field_count_++;
          if (FLAG_trace_precompiler) {
            THR_Print("Dropping field %s\n",
                      field.ToCString());
          }
        }
      }

      if (retained_fields.Length() > 0) {
        fields = Array::MakeArray(retained_fields);
        cls.SetFields(fields);
      } else {
        cls.SetFields(Object::empty_array());
      }
    }
  }
}


void Precompiler::DropTypes() {
  ObjectStore* object_store = I->object_store();
  GrowableObjectArray& retained_types =
      GrowableObjectArray::Handle(Z, GrowableObjectArray::New());
  Array& types_array = Array::Handle(Z);
  Type& type = Type::Handle(Z);
  // First drop all the types that are not referenced.
  {
    CanonicalTypeSet types_table(Z, object_store->canonical_types());
    types_array = HashTables::ToArray(types_table, false);
    for (intptr_t i = 0; i < (types_array.Length() - 1); i++) {
      type ^= types_array.At(i);
      bool retain = types_to_retain_.Lookup(&type) != NULL;
      if (retain) {
        retained_types.Add(type);
      } else {
        dropped_type_count_++;
      }
    }
    types_table.Release();
  }

  // Now construct a new type table and save in the object store.
  const intptr_t dict_size =
      Utils::RoundUpToPowerOfTwo(retained_types.Length() * 4 / 3);
  types_array = HashTables::New<CanonicalTypeSet>(dict_size, Heap::kOld);
  CanonicalTypeSet types_table(Z, types_array.raw());
  bool present;
  for (intptr_t i = 0; i < retained_types.Length(); i++) {
    type ^= retained_types.At(i);
    present = types_table.Insert(type);
    ASSERT(!present);
  }
  object_store->set_canonical_types(types_table.Release());
}


void Precompiler::DropTypeArguments() {
  ObjectStore* object_store = I->object_store();
  Array& typeargs_array = Array::Handle(Z);
  GrowableObjectArray& retained_typeargs =
      GrowableObjectArray::Handle(Z, GrowableObjectArray::New());
  TypeArguments& typeargs = TypeArguments::Handle(Z);
  // First drop all the type arguments that are not referenced.
  {
    CanonicalTypeArgumentsSet typeargs_table(
        Z, object_store->canonical_type_arguments());
    typeargs_array = HashTables::ToArray(typeargs_table, false);
    for (intptr_t i = 0; i < (typeargs_array.Length() - 1); i++) {
      typeargs ^= typeargs_array.At(i);
      bool retain = typeargs_to_retain_.Lookup(&typeargs) != NULL;
      if (retain) {
        retained_typeargs.Add(typeargs);
      } else {
        dropped_typearg_count_++;
      }
    }
    typeargs_table.Release();
  }

  // Now construct a new type arguments table and save in the object store.
  const intptr_t dict_size =
      Utils::RoundUpToPowerOfTwo(retained_typeargs.Length() * 4 / 3);
  typeargs_array = HashTables::New<CanonicalTypeArgumentsSet>(dict_size,
                                                              Heap::kOld);
  CanonicalTypeArgumentsSet typeargs_table(Z, typeargs_array.raw());
  bool present;
  for (intptr_t i = 0; i < retained_typeargs.Length(); i++) {
    typeargs ^= retained_typeargs.At(i);
    present = typeargs_table.Insert(typeargs);
    ASSERT(!present);
  }
  object_store->set_canonical_type_arguments(typeargs_table.Release());
}


void Precompiler::DropScriptData() {
  Library& lib = Library::Handle(Z);
  Array& scripts = Array::Handle(Z);
  Script& script = Script::Handle(Z);
  const TokenStream& null_tokens = TokenStream::Handle(Z);
  for (intptr_t i = 0; i < libraries_.Length(); i++) {
    lib ^= libraries_.At(i);
    scripts = lib.LoadedScripts();
    for (intptr_t j = 0; j < scripts.Length(); j++) {
      script ^= scripts.At(j);
      script.set_compile_time_constants(Array::null_array());
      script.set_source(String::null_string());
      script.set_tokens(null_tokens);
    }
  }
}


void Precompiler::TraceTypesFromRetainedClasses() {
  Library& lib = Library::Handle(Z);
  Class& cls = Class::Handle(Z);
  Array& members = Array::Handle(Z);
  Array& constants = Array::Handle(Z);
  GrowableObjectArray& retained_constants = GrowableObjectArray::Handle(Z);
  Instance& constant = Instance::Handle(Z);

  for (intptr_t i = 0; i < libraries_.Length(); i++) {
    lib ^= libraries_.At(i);
    ClassDictionaryIterator it(lib, ClassDictionaryIterator::kIteratePrivate);
    while (it.HasNext()) {
      cls = it.GetNextClass();
      if (cls.IsDynamicClass()) {
        continue;  // class 'dynamic' is in the read-only VM isolate.
      }

      // The subclasses array is only needed for CHA.
      cls.ClearDirectSubclasses();

      bool retain = false;
      members = cls.fields();
      if (members.Length() > 0) {
        retain = true;
      }
      members = cls.functions();
      if (members.Length() > 0) {
        retain = true;
      }
      if (cls.is_allocated()) {
        retain = true;
      }
      if (cls.is_enum_class()) {
        // Enum classes have live instances, so we cannot unregister
        // them.
        retain = true;
      }

      constants = cls.constants();
      retained_constants = GrowableObjectArray::New();
      for (intptr_t j = 0; j < constants.Length(); j++) {
        constant ^= constants.At(j);
        bool retain = consts_to_retain_.Lookup(&constant) != NULL;
        if (retain) {
          retained_constants.Add(constant);
        }
      }
      intptr_t cid = cls.id();
      if ((cid == kMintCid) || (cid == kBigintCid) || (cid == kDoubleCid)) {
        // Constants stored as a plain list, no rehashing needed.
        constants = Array::MakeArray(retained_constants);
        cls.set_constants(constants);
      } else {
        // Rehash.
        cls.set_constants(Object::empty_array());
        for (intptr_t j = 0; j < retained_constants.Length(); j++) {
          constant ^= retained_constants.At(j);
          cls.InsertCanonicalConstant(Z, constant);
        }
      }

      if (retained_constants.Length() > 0) {
        ASSERT(retain);  // This shouldn't be the reason we keep a class.
        retain = true;
      }

      if (retain) {
        AddTypesOf(cls);
      }
    }
  }
}


void Precompiler::DropClasses() {
  Library& lib = Library::Handle(Z);
  Class& cls = Class::Handle(Z);
  Array& constants = Array::Handle(Z);
  String& name = String::Handle(Z);

#if defined(DEBUG)
  // We are about to remove classes from the class table. For this to be safe,
  // there must be no instances of these classes on the heap, not even
  // corpses because the class table entry may be used to find the size of
  // corpses. Request a full GC and wait for the sweeper tasks to finish before
  // we continue.
  I->heap()->CollectAllGarbage();
  I->heap()->WaitForSweeperTasks();
#endif

  ClassTable* class_table = I->class_table();
  intptr_t num_cids = class_table->NumCids();

  for (intptr_t cid = kNumPredefinedCids; cid < num_cids; cid++) {
    if (!class_table->IsValidIndex(cid)) continue;
    if (!class_table->HasValidClassAt(cid)) continue;

    cls = class_table->At(cid);
    ASSERT(!cls.IsNull());

    if (cls.IsTopLevel()) {
      // Top-level classes are referenced directly from their library. They
      // will only be removed as a consequence of an entire library being
      // removed.
      continue;
    }

    bool retain = classes_to_retain_.Lookup(&cls) != NULL;
    if (retain) {
      continue;
    }

    ASSERT(!cls.is_allocated());
    constants = cls.constants();
    ASSERT(constants.Length() == 0);

#if defined(DEBUG)
    intptr_t instances =
        class_table->StatsWithUpdatedSize(cid)->post_gc.new_count +
        class_table->StatsWithUpdatedSize(cid)->post_gc.old_count;
    if (instances != 0) {
      FATAL2("Want to drop class %s, but it has %" Pd " instances\n",
             cls.ToCString(),
             instances);
    }
#endif

    dropped_class_count_++;
    if (FLAG_trace_precompiler) {
      THR_Print("Dropping class %" Pd " %s\n", cid, cls.ToCString());
    }

#if defined(DEBUG)
    class_table->Unregister(cid);
#endif
    cls.set_id(kIllegalCid);  // We check this when serializing.

    lib = cls.library();
    name = cls.DictionaryName();
    lib.RemoveObject(cls, name);
  }
}


void Precompiler::DropLibraries() {
  const GrowableObjectArray& retained_libraries =
      GrowableObjectArray::Handle(Z, GrowableObjectArray::New());
  const Library& root_lib = Library::Handle(Z,
      I->object_store()->root_library());
  Library& lib = Library::Handle(Z);

  for (intptr_t i = 0; i < libraries_.Length(); i++) {
    lib ^= libraries_.At(i);
    lib.DropDependencies();
    intptr_t entries = 0;
    DictionaryIterator it(lib);
    while (it.HasNext()) {
      it.GetNext();
      entries++;
    }
    bool retain = false;
    if (entries > 0) {
      retain = true;
    } else if (lib.is_dart_scheme()) {
      // The core libraries are referenced from the object store.
      retain = true;
    } else if (lib.raw() == root_lib.raw()) {
      // The root library might have no surviving members if it only exports
      // main from another library. It will still be referenced from the object
      // store, so retain it.
      retain = true;
    } else {
      // A type for a top-level class may be referenced from an object pool as
      // part of an error message.
      const Class& top = Class::Handle(Z, lib.toplevel_class());
      if (classes_to_retain_.Lookup(&top) != NULL) {
        retain = true;
      }
    }

    if (retain) {
      lib.set_index(retained_libraries.Length());
      retained_libraries.Add(lib);
    } else {
      dropped_library_count_++;
      lib.set_index(-1);
      if (FLAG_trace_precompiler) {
        THR_Print("Dropping library %s\n", lib.ToCString());
      }
    }
  }

  Library::RegisterLibraries(T, retained_libraries);
  libraries_ = retained_libraries.raw();
}


void Precompiler::BindStaticCalls() {
  class BindStaticCallsVisitor : public FunctionVisitor {
   public:
    explicit BindStaticCallsVisitor(Zone* zone) :
        code_(Code::Handle(zone)),
        table_(Array::Handle(zone)),
        pc_offset_(Smi::Handle(zone)),
        target_(Function::Handle(zone)),
        target_code_(Code::Handle(zone)) {
    }

    void Visit(const Function& function) {
      if (!function.HasCode()) {
        return;
      }
      code_ = function.CurrentCode();
      table_ = code_.static_calls_target_table();

      for (intptr_t i = 0;
           i < table_.Length();
           i += Code::kSCallTableEntryLength) {
        pc_offset_ ^= table_.At(i + Code::kSCallTableOffsetEntry);
        target_ ^= table_.At(i + Code::kSCallTableFunctionEntry);
        if (target_.IsNull()) {
          target_code_ ^= table_.At(i + Code::kSCallTableCodeEntry);
          ASSERT(!target_code_.IsNull());
          ASSERT(!target_code_.IsFunctionCode());
          // Allocation stub or AllocateContext or AllocateArray or ...
        } else {
          // Static calls initially call the CallStaticFunction stub because
          // their target might not be compiled yet. After tree shaking, all
          // static call targets are compiled.
          // Cf. runtime entry PatchStaticCall called from CallStaticFunction
          // stub.
          ASSERT(target_.HasCode());
          target_code_ ^= target_.CurrentCode();
          uword pc = pc_offset_.Value() + code_.PayloadStart();
          CodePatcher::PatchStaticCallAt(pc, code_, target_code_);
        }
      }

      // We won't patch static calls anymore, so drop the static call table to
      // save space.
      code_.set_static_calls_target_table(Object::empty_array());
    }

   private:
    Code& code_;
    Array& table_;
    Smi& pc_offset_;
    Function& target_;
    Code& target_code_;
  };

  BindStaticCallsVisitor visitor(Z);
  VisitFunctions(&visitor);
}


void Precompiler::SwitchICCalls() {
#if !defined(TARGET_ARCH_DBC)
  // Now that all functions have been compiled, we can switch to an instance
  // call sequence that loads the Code object and entry point directly from
  // the ic data array instead indirectly through a Function in the ic data
  // array. Iterate all the object pools and rewrite the ic data from
  // (cid, target function, count) to (cid, target code, entry point), and
  // replace the ICCallThroughFunction stub with ICCallThroughCode.

  class SwitchICCallsVisitor : public FunctionVisitor {
   public:
    explicit SwitchICCallsVisitor(Zone* zone) :
        zone_(zone),
        code_(Code::Handle(zone)),
        pool_(ObjectPool::Handle(zone)),
        entry_(Object::Handle(zone)),
        ic_(ICData::Handle(zone)),
        target_name_(String::Handle(zone)),
        args_descriptor_(Array::Handle(zone)),
        unlinked_(UnlinkedCall::Handle(zone)),
        target_code_(Code::Handle(zone)),
        canonical_unlinked_calls_() {
    }

    void Visit(const Function& function) {
      if (!function.HasCode()) {
        return;
      }

      code_ = function.CurrentCode();
      pool_ = code_.object_pool();
      for (intptr_t i = 0; i < pool_.Length(); i++) {
        if (pool_.InfoAt(i) != ObjectPool::kTaggedObject) continue;
        entry_ = pool_.ObjectAt(i);
        if (entry_.IsICData()) {
          // The only IC calls generated by precompilation are for switchable
          // calls.
          ic_ ^= entry_.raw();
          ic_.ResetSwitchable(zone_);

          unlinked_ = UnlinkedCall::New();
          target_name_ = ic_.target_name();
          unlinked_.set_target_name(target_name_);
          args_descriptor_ = ic_.arguments_descriptor();
          unlinked_.set_args_descriptor(args_descriptor_);
          unlinked_ = DedupUnlinkedCall(unlinked_);
          pool_.SetObjectAt(i, unlinked_);
        } else if (entry_.raw() ==
                   StubCode::ICCallThroughFunction_entry()->code()) {
          target_code_ = StubCode::UnlinkedCall_entry()->code();
          pool_.SetObjectAt(i, target_code_);
        }
      }
    }

    RawUnlinkedCall* DedupUnlinkedCall(const UnlinkedCall& unlinked) {
      const UnlinkedCall* canonical_unlinked =
          canonical_unlinked_calls_.LookupValue(&unlinked);
      if (canonical_unlinked == NULL) {
        canonical_unlinked_calls_.Insert(
            &UnlinkedCall::ZoneHandle(zone_, unlinked.raw()));
        return unlinked.raw();
      } else {
        return canonical_unlinked->raw();
      }
    }

   private:
    Zone* zone_;
    Code& code_;
    ObjectPool& pool_;
    Object& entry_;
    ICData& ic_;
    String& target_name_;
    Array& args_descriptor_;
    UnlinkedCall& unlinked_;
    Code& target_code_;
    UnlinkedCallSet canonical_unlinked_calls_;
  };

  ASSERT(!I->compilation_allowed());
  SwitchICCallsVisitor visitor(Z);
  VisitFunctions(&visitor);
#endif
}


void Precompiler::ShareMegamorphicBuckets() {
  const GrowableObjectArray& table = GrowableObjectArray::Handle(Z,
      I->object_store()->megamorphic_cache_table());
  if (table.IsNull()) return;
  MegamorphicCache& cache = MegamorphicCache::Handle(Z);

  const intptr_t capacity = 1;
  const Array& buckets = Array::Handle(Z,
      Array::New(MegamorphicCache::kEntryLength * capacity, Heap::kOld));
  const Function& handler =
      Function::Handle(Z, MegamorphicCacheTable::miss_handler(I));
  MegamorphicCache::SetEntry(buckets, 0,
                             MegamorphicCache::smi_illegal_cid(), handler);

  for (intptr_t i = 0; i < table.Length(); i++) {
    cache ^= table.At(i);
    cache.set_buckets(buckets);
    cache.set_mask(capacity - 1);
    cache.set_filled_entry_count(0);
  }
}


void Precompiler::DedupStackmaps() {
  class DedupStackmapsVisitor : public FunctionVisitor {
   public:
    explicit DedupStackmapsVisitor(Zone* zone) :
      zone_(zone),
      canonical_stackmaps_(),
      code_(Code::Handle(zone)),
      stackmaps_(Array::Handle(zone)),
      stackmap_(Stackmap::Handle(zone)) {
    }

    void Visit(const Function& function) {
      if (!function.HasCode()) {
        return;
      }
      code_ = function.CurrentCode();
      stackmaps_ = code_.stackmaps();
      if (stackmaps_.IsNull()) return;
      for (intptr_t i = 0; i < stackmaps_.Length(); i++) {
        stackmap_ ^= stackmaps_.At(i);
        stackmap_ = DedupStackmap(stackmap_);
        stackmaps_.SetAt(i, stackmap_);
      }
    }

    RawStackmap* DedupStackmap(const Stackmap& stackmap) {
      const Stackmap* canonical_stackmap =
          canonical_stackmaps_.LookupValue(&stackmap);
      if (canonical_stackmap == NULL) {
        canonical_stackmaps_.Insert(
            &Stackmap::ZoneHandle(zone_, stackmap.raw()));
        return stackmap.raw();
      } else {
        return canonical_stackmap->raw();
      }
    }

   private:
    Zone* zone_;
    StackmapSet canonical_stackmaps_;
    Code& code_;
    Array& stackmaps_;
    Stackmap& stackmap_;
  };

  DedupStackmapsVisitor visitor(Z);
  VisitFunctions(&visitor);
}


void Precompiler::DedupLists() {
  class DedupListsVisitor : public FunctionVisitor {
   public:
    explicit DedupListsVisitor(Zone* zone) :
      zone_(zone),
      canonical_lists_(),
      code_(Code::Handle(zone)),
      list_(Array::Handle(zone)) {
    }

    void Visit(const Function& function) {
      code_ = function.CurrentCode();
      if (!code_.IsNull()) {
        list_ = code_.stackmaps();
        if (!list_.IsNull()) {
          list_ = DedupList(list_);
          code_.set_stackmaps(list_);
        }
      }

      list_ = function.parameter_types();
      if (!list_.IsNull()) {
        if (!function.IsSignatureFunction() &&
            !function.IsClosureFunction() &&
            (function.name() != Symbols::Call().raw()) &&
            !list_.InVMHeap()) {
          // Parameter types not needed for function type tests.
          for (intptr_t i = 0; i < list_.Length(); i++) {
            list_.SetAt(i, Object::dynamic_type());
          }
        }
        list_ = DedupList(list_);
        function.set_parameter_types(list_);
      }

      list_ = function.parameter_names();
      if (!list_.IsNull()) {
        if (!function.HasOptionalNamedParameters() &&
            !list_.InVMHeap()) {
          // Parameter names not needed for resolution.
          for (intptr_t i = 0; i < list_.Length(); i++) {
            list_.SetAt(i, Symbols::OptimizedOut());
          }
        }
        list_ = DedupList(list_);
        function.set_parameter_names(list_);
      }
    }

    RawArray* DedupList(const Array& list) {
      const Array* canonical_list = canonical_lists_.LookupValue(&list);
      if (canonical_list == NULL) {
        canonical_lists_.Insert(&Array::ZoneHandle(zone_, list.raw()));
        return list.raw();
      } else {
        return canonical_list->raw();
      }
    }

   private:
    Zone* zone_;
    ArraySet canonical_lists_;
    Code& code_;
    Array& list_;
  };

  DedupListsVisitor visitor(Z);
  VisitFunctions(&visitor);
}


void Precompiler::DedupInstructions() {
  class DedupInstructionsVisitor : public FunctionVisitor {
   public:
    explicit DedupInstructionsVisitor(Zone* zone) :
      zone_(zone),
      canonical_instructions_set_(),
      code_(Code::Handle(zone)),
      instructions_(Instructions::Handle(zone)) {
    }

    void Visit(const Function& function) {
      if (!function.HasCode()) {
        ASSERT(function.HasImplicitClosureFunction());
        return;
      }
      code_ = function.CurrentCode();
      instructions_ = code_.instructions();
      instructions_ = DedupOneInstructions(instructions_);
      code_.SetActiveInstructions(instructions_);
      code_.set_instructions(instructions_);
      function.SetInstructions(code_);  // Update cached entry point.
    }

    RawInstructions* DedupOneInstructions(const Instructions& instructions) {
      const Instructions* canonical_instructions =
          canonical_instructions_set_.LookupValue(&instructions);
      if (canonical_instructions == NULL) {
        canonical_instructions_set_.Insert(
            &Instructions::ZoneHandle(zone_, instructions.raw()));
        return instructions.raw();
      } else {
        return canonical_instructions->raw();
      }
    }

   private:
    Zone* zone_;
    InstructionsSet canonical_instructions_set_;
    Code& code_;
    Instructions& instructions_;
  };

  DedupInstructionsVisitor visitor(Z);
  VisitFunctions(&visitor);
}


void Precompiler::VisitClasses(ClassVisitor* visitor) {
  Library& lib = Library::Handle(Z);
  Class& cls = Class::Handle(Z);

  for (intptr_t i = 0; i < libraries_.Length(); i++) {
    lib ^= libraries_.At(i);
    ClassDictionaryIterator it(lib, ClassDictionaryIterator::kIteratePrivate);
    while (it.HasNext()) {
      cls = it.GetNextClass();
      if (cls.IsDynamicClass()) {
        continue;  // class 'dynamic' is in the read-only VM isolate.
      }
      visitor->Visit(cls);
    }
  }
}


void Precompiler::VisitFunctions(FunctionVisitor* visitor) {
  Library& lib = Library::Handle(Z);
  Class& cls = Class::Handle(Z);
  Array& functions = Array::Handle(Z);
  Array& fields = Array::Handle(Z);
  Field& field = Field::Handle(Z);
  Object& object = Object::Handle(Z);
  Function& function = Function::Handle(Z);
  GrowableObjectArray& closures = GrowableObjectArray::Handle(Z);

  for (intptr_t i = 0; i < libraries_.Length(); i++) {
    lib ^= libraries_.At(i);
    ClassDictionaryIterator it(lib, ClassDictionaryIterator::kIteratePrivate);
    while (it.HasNext()) {
      cls = it.GetNextClass();
      if (cls.IsDynamicClass()) {
        continue;  // class 'dynamic' is in the read-only VM isolate.
      }

      functions = cls.functions();
      for (intptr_t j = 0; j < functions.Length(); j++) {
        function ^= functions.At(j);
        visitor->Visit(function);
        if (function.HasImplicitClosureFunction()) {
          function = function.ImplicitClosureFunction();
          visitor->Visit(function);
        }
      }

      functions = cls.invocation_dispatcher_cache();
      for (intptr_t j = 0; j < functions.Length(); j++) {
        object = functions.At(j);
        if (object.IsFunction()) {
          function ^= functions.At(j);
          visitor->Visit(function);
        }
      }
      fields = cls.fields();
      for (intptr_t j = 0; j < fields.Length(); j++) {
        field ^= fields.At(j);
        if (field.is_static() && field.HasPrecompiledInitializer()) {
          function ^= field.PrecompiledInitializer();
          visitor->Visit(function);
        }
      }
    }
  }
  closures = isolate()->object_store()->closure_functions();
  for (intptr_t j = 0; j < closures.Length(); j++) {
    function ^= closures.At(j);
    visitor->Visit(function);
    ASSERT(!function.HasImplicitClosureFunction());
  }
}


void Precompiler::FinalizeAllClasses() {
  Library& lib = Library::Handle(Z);
  Class& cls = Class::Handle(Z);

  for (intptr_t i = 0; i < libraries_.Length(); i++) {
    lib ^= libraries_.At(i);
    if (!lib.Loaded()) {
      String& uri = String::Handle(Z, lib.url());
      String& msg = String::Handle(Z, String::NewFormatted(
          "Library '%s' is not loaded. "
          "Did you forget to call Dart_FinalizeLoading?", uri.ToCString()));
      Jump(Error::Handle(Z, ApiError::New(msg)));
    }

    ClassDictionaryIterator it(lib, ClassDictionaryIterator::kIteratePrivate);
    while (it.HasNext()) {
      cls = it.GetNextClass();
      if (cls.IsDynamicClass()) {
        continue;  // class 'dynamic' is in the read-only VM isolate.
      }
      error_ = cls.EnsureIsFinalized(T);
      if (!error_.IsNull()) {
        Jump(error_);
      }
    }
  }
  I->set_all_classes_finalized(true);
}


void Precompiler::SortClasses() {
  ClassTable* table = I->class_table();
  intptr_t num_cids = table->NumCids();
  intptr_t* old_to_new_cid = new intptr_t[num_cids];
  for (intptr_t cid = 0; cid < kNumPredefinedCids; cid++) {
    old_to_new_cid[cid] = cid;  // The predefined classes cannot change cids.
  }
  for (intptr_t cid = kNumPredefinedCids; cid < num_cids; cid++) {
    old_to_new_cid[cid] = -1;
  }

  intptr_t next_new_cid = kNumPredefinedCids;
  GrowableArray<intptr_t> dfs_stack;
  Class& cls = Class::Handle(Z);
  GrowableObjectArray& subclasses = GrowableObjectArray::Handle(Z);

  // Object doesn't use its subclasses list.
  for (intptr_t cid = kNumPredefinedCids; cid < num_cids; cid++) {
    if (!table->HasValidClassAt(cid)) {
      continue;
    }
    cls = table->At(cid);
    if (cls.is_patch()) {
      continue;
    }
    if (cls.SuperClass() == I->object_store()->object_class()) {
      dfs_stack.Add(cid);
    }
  }

  while (dfs_stack.length() > 0) {
    intptr_t cid = dfs_stack.RemoveLast();
    ASSERT(table->HasValidClassAt(cid));
    cls = table->At(cid);
    ASSERT(!cls.IsNull());
    if (old_to_new_cid[cid] == -1) {
      old_to_new_cid[cid] = next_new_cid++;
      if (FLAG_trace_precompiler) {
        THR_Print("%" Pd ": %s, was %" Pd "\n",
                  old_to_new_cid[cid], cls.ToCString(), cid);
      }
    }
    subclasses = cls.direct_subclasses();
    if (!subclasses.IsNull()) {
      for (intptr_t i = 0; i < subclasses.Length(); i++) {
        cls ^= subclasses.At(i);
        ASSERT(!cls.IsNull());
        dfs_stack.Add(cls.id());
      }
    }
  }

  // Top-level classes, typedefs, patch classes, etc.
  for (intptr_t cid = kNumPredefinedCids; cid < num_cids; cid++) {
    if (old_to_new_cid[cid] == -1) {
      old_to_new_cid[cid] = next_new_cid++;
      if (FLAG_trace_precompiler && table->HasValidClassAt(cid)) {
        cls = table->At(cid);
        THR_Print("%" Pd ": %s, was %" Pd "\n",
                  old_to_new_cid[cid], cls.ToCString(), cid);
      }
    }
  }
  ASSERT(next_new_cid == num_cids);

  RemapClassIds(old_to_new_cid);
  delete[] old_to_new_cid;
}


class CidRewriteVisitor : public ObjectVisitor {
 public:
  explicit CidRewriteVisitor(intptr_t* old_to_new_cids)
      : old_to_new_cids_(old_to_new_cids) { }

  intptr_t Map(intptr_t cid) {
    ASSERT(cid != -1);
    return old_to_new_cids_[cid];
  }

  void VisitObject(RawObject* obj) {
    if (obj->IsClass()) {
      RawClass* cls = Class::RawCast(obj);
      cls->ptr()->id_ = Map(cls->ptr()->id_);
    } else if (obj->IsField()) {
      RawField* field = Field::RawCast(obj);
      field->ptr()->guarded_cid_ = Map(field->ptr()->guarded_cid_);
      field->ptr()->is_nullable_ = Map(field->ptr()->is_nullable_);
    } else if (obj->IsTypeParameter()) {
      RawTypeParameter* param = TypeParameter::RawCast(obj);
      param->ptr()->parameterized_class_id_ =
          Map(param->ptr()->parameterized_class_id_);
    } else if (obj->IsType()) {
      RawType* type = Type::RawCast(obj);
      RawObject* id = type->ptr()->type_class_id_;
      if (!id->IsHeapObject()) {
        type->ptr()->type_class_id_ =
            Smi::New(Map(Smi::Value(Smi::RawCast(id))));
      }
    } else {
      intptr_t old_cid = obj->GetClassId();
      intptr_t new_cid = Map(old_cid);
      if (old_cid != new_cid) {
        // Don't touch objects that are unchanged. In particular, Instructions,
        // which are write-protected.
        obj->SetClassId(new_cid);
      }
    }
  }

 private:
  intptr_t* old_to_new_cids_;
};


void Precompiler::RemapClassIds(intptr_t* old_to_new_cid) {
  // Code, ICData, allocation stubs have now-invalid cids.
  ClearAllCode();

  {
    HeapIterationScope his;

    // Update the class table. Do it before rewriting cids in headers, as the
    // heap walkers load an object's size *after* calling the visitor.
    I->class_table()->Remap(old_to_new_cid);

    // Rewrite cids in headers and cids in Classes, Fields, Types and
    // TypeParameters.
    {
      CidRewriteVisitor visitor(old_to_new_cid);
      I->heap()->VisitObjects(&visitor);
    }
  }

#if defined(DEBUG)
  I->class_table()->Validate();
  I->heap()->Verify();
#endif
}


void Precompiler::ResetPrecompilerState() {
  changed_ = false;
  function_count_ = 0;
  class_count_ = 0;
  selector_count_ = 0;
  dropped_function_count_ = 0;
  dropped_field_count_ = 0;
  ASSERT(pending_functions_.Length() == 0);
  sent_selectors_.Clear();
  enqueued_functions_.Clear();

  Library& lib = Library::Handle(Z);
  Class& cls = Class::Handle(Z);

  for (intptr_t i = 0; i < libraries_.Length(); i++) {
    lib ^= libraries_.At(i);
    ClassDictionaryIterator it(lib, ClassDictionaryIterator::kIteratePrivate);
    while (it.HasNext()) {
      cls = it.GetNextClass();
      if (cls.IsDynamicClass()) {
        continue;  // class 'dynamic' is in the read-only VM isolate.
      }
      cls.set_is_allocated(false);
    }
  }
}


void PrecompileParsedFunctionHelper::FinalizeCompilation(
    Assembler* assembler,
    FlowGraphCompiler* graph_compiler,
    FlowGraph* flow_graph) {
  const Function& function = parsed_function()->function();
  Zone* const zone = thread()->zone();

  CSTAT_TIMER_SCOPE(thread(), codefinalizer_timer);
  // CreateDeoptInfo uses the object pool and needs to be done before
  // FinalizeCode.
  const Array& deopt_info_array =
      Array::Handle(zone, graph_compiler->CreateDeoptInfo(assembler));
  INC_STAT(thread(), total_code_size,
           deopt_info_array.Length() * sizeof(uword));
  // Allocates instruction object. Since this occurs only at safepoint,
  // there can be no concurrent access to the instruction page.
  const Code& code = Code::Handle(
      Code::FinalizeCode(function, assembler, optimized()));
  code.set_is_optimized(optimized());
  code.set_owner(function);
  if (!function.IsOptimizable()) {
    // A function with huge unoptimized code can become non-optimizable
    // after generating unoptimized code.
    function.set_usage_counter(INT_MIN);
  }

  const Array& intervals = graph_compiler->inlined_code_intervals();
  INC_STAT(thread(), total_code_size,
           intervals.Length() * sizeof(uword));
  code.SetInlinedIntervals(intervals);

  const Array& inlined_id_array =
      Array::Handle(zone, graph_compiler->InliningIdToFunction());
  INC_STAT(thread(), total_code_size,
           inlined_id_array.Length() * sizeof(uword));
  code.SetInlinedIdToFunction(inlined_id_array);

  const Array& caller_inlining_id_map_array =
      Array::Handle(zone, graph_compiler->CallerInliningIdMap());
  INC_STAT(thread(), total_code_size,
           caller_inlining_id_map_array.Length() * sizeof(uword));
  code.SetInlinedCallerIdMap(caller_inlining_id_map_array);

  graph_compiler->FinalizePcDescriptors(code);
  code.set_deopt_info_array(deopt_info_array);

  graph_compiler->FinalizeStackmaps(code);
  graph_compiler->FinalizeVarDescriptors(code);
  graph_compiler->FinalizeExceptionHandlers(code);
  graph_compiler->FinalizeStaticCallTargetsTable(code);

  if (optimized()) {
    // Installs code while at safepoint.
    ASSERT(thread()->IsMutatorThread());
    function.InstallOptimizedCode(code, /* is_osr = */ false);
  } else {  // not optimized.
    function.set_unoptimized_code(code);
    function.AttachCode(code);
  }
  ASSERT(!parsed_function()->HasDeferredPrefixes());
  ASSERT(FLAG_load_deferred_eagerly);
}


// Return false if bailed out.
// If optimized_result_code is not NULL then it is caller's responsibility
// to install code.
bool PrecompileParsedFunctionHelper::Compile(CompilationPipeline* pipeline) {
  ASSERT(FLAG_precompiled_mode);
  const Function& function = parsed_function()->function();
  if (optimized() && !function.IsOptimizable()) {
    // All functions compiled by precompiler must be optimizable.
    UNREACHABLE();
    return false;
  }
  bool is_compiled = false;
  Zone* const zone = thread()->zone();
#ifndef PRODUCT
  TimelineStream* compiler_timeline = Timeline::GetCompilerStream();
#endif  // !PRODUCT
  CSTAT_TIMER_SCOPE(thread(), codegen_timer);
  HANDLESCOPE(thread());

  // We may reattempt compilation if the function needs to be assembled using
  // far branches on ARM and MIPS. In the else branch of the setjmp call,
  // done is set to false, and use_far_branches is set to true if there is a
  // longjmp from the ARM or MIPS assemblers. In all other paths through this
  // while loop, done is set to true. use_far_branches is always false on ia32
  // and x64.
  bool done = false;
  // volatile because the variable may be clobbered by a longjmp.
  volatile bool use_far_branches = false;
  volatile bool use_speculative_inlining =
      FLAG_max_speculative_inlining_attempts > 0;
  GrowableArray<intptr_t> inlining_black_list;

  while (!done) {
    const intptr_t prev_deopt_id = thread()->deopt_id();
    thread()->set_deopt_id(0);
    LongJumpScope jump;
    const intptr_t val = setjmp(*jump.Set());
    if (val == 0) {
      FlowGraph* flow_graph = NULL;

      // Class hierarchy analysis is registered with the thread in the
      // constructor and unregisters itself upon destruction.
      CHA cha(thread());

      // TimerScope needs an isolate to be properly terminated in case of a
      // LongJump.
      {
        CSTAT_TIMER_SCOPE(thread(), graphbuilder_timer);
        ZoneGrowableArray<const ICData*>* ic_data_array =
            new(zone) ZoneGrowableArray<const ICData*>();
#ifndef PRODUCT
        TimelineDurationScope tds(thread(),
                                  compiler_timeline,
                                  "BuildFlowGraph");
#endif  // !PRODUCT
        flow_graph = pipeline->BuildFlowGraph(zone,
                                              parsed_function(),
                                              *ic_data_array,
                                              Compiler::kNoOSRDeoptId);
      }

      const bool print_flow_graph =
          (FLAG_print_flow_graph ||
           (optimized() && FLAG_print_flow_graph_optimized)) &&
          FlowGraphPrinter::ShouldPrint(function);

      if (print_flow_graph) {
        FlowGraphPrinter::PrintGraph("Before Optimizations", flow_graph);
      }

      if (optimized()) {
#ifndef PRODUCT
        TimelineDurationScope tds(thread(),
                                  compiler_timeline,
                                  "ComputeSSA");
#endif  // !PRODUCT
        CSTAT_TIMER_SCOPE(thread(), ssa_timer);
        // Transform to SSA (virtual register 0 and no inlining arguments).
        flow_graph->ComputeSSA(0, NULL);
        DEBUG_ASSERT(flow_graph->VerifyUseLists());
        if (print_flow_graph) {
          FlowGraphPrinter::PrintGraph("After SSA", flow_graph);
        }
      }

      // Maps inline_id_to_function[inline_id] -> function. Top scope
      // function has inline_id 0. The map is populated by the inliner.
      GrowableArray<const Function*> inline_id_to_function;
      // Token position where inlining occured.
      GrowableArray<TokenPosition> inline_id_to_token_pos;
      // For a given inlining-id(index) specifies the caller's inlining-id.
      GrowableArray<intptr_t> caller_inline_id;
      // Collect all instance fields that are loaded in the graph and
      // have non-generic type feedback attached to them that can
      // potentially affect optimizations.
      if (optimized()) {
#ifndef PRODUCT
        TimelineDurationScope tds(thread(),
                                  compiler_timeline,
                                  "OptimizationPasses");
#endif  // !PRODUCT
        inline_id_to_function.Add(&function);
        // We do not add the token position now because we don't know the
        // position of the inlined call until later. A side effect of this
        // is that the length of |inline_id_to_function| is always larger
        // than the length of |inline_id_to_token_pos| by one.
        // Top scope function has no caller (-1). We do this because we expect
        // all token positions to be at an inlined call.
        // Top scope function has no caller (-1).
        caller_inline_id.Add(-1);
        CSTAT_TIMER_SCOPE(thread(), graphoptimizer_timer);

        AotOptimizer optimizer(precompiler_,
                               flow_graph,
                               use_speculative_inlining,
                               &inlining_black_list);
        optimizer.PopulateWithICData();

        optimizer.ApplyClassIds();
        DEBUG_ASSERT(flow_graph->VerifyUseLists());

        FlowGraphTypePropagator::Propagate(flow_graph);
        DEBUG_ASSERT(flow_graph->VerifyUseLists());

        optimizer.ApplyICData();
        DEBUG_ASSERT(flow_graph->VerifyUseLists());

        // Optimize (a << b) & c patterns, merge operations.
        // Run early in order to have more opportunity to optimize left shifts.
        flow_graph->TryOptimizePatterns();
        DEBUG_ASSERT(flow_graph->VerifyUseLists());

        FlowGraphInliner::SetInliningId(flow_graph, 0);

        // Inlining (mutates the flow graph)
        if (FLAG_use_inlining) {
#ifndef PRODUCT
          TimelineDurationScope tds2(thread(),
                                     compiler_timeline,
                                     "Inlining");
#endif  // !PRODUCT
          CSTAT_TIMER_SCOPE(thread(), graphinliner_timer);
          // Propagate types to create more inlining opportunities.
          FlowGraphTypePropagator::Propagate(flow_graph);
          DEBUG_ASSERT(flow_graph->VerifyUseLists());

          // Use propagated class-ids to create more inlining opportunities.
          optimizer.ApplyClassIds();
          DEBUG_ASSERT(flow_graph->VerifyUseLists());

          FlowGraphInliner inliner(flow_graph,
                                   &inline_id_to_function,
                                   &inline_id_to_token_pos,
                                   &caller_inline_id,
                                   use_speculative_inlining,
                                   &inlining_black_list,
                                   precompiler_);
          inliner.Inline();
          // Use lists are maintained and validated by the inliner.
          DEBUG_ASSERT(flow_graph->VerifyUseLists());
        }

        // Propagate types and eliminate more type tests.
        FlowGraphTypePropagator::Propagate(flow_graph);
        DEBUG_ASSERT(flow_graph->VerifyUseLists());

        {
#ifndef PRODUCT
          TimelineDurationScope tds2(thread(),
                                     compiler_timeline,
                                     "ApplyClassIds");
#endif  // !PRODUCT
          // Use propagated class-ids to optimize further.
          optimizer.ApplyClassIds();
          DEBUG_ASSERT(flow_graph->VerifyUseLists());
        }

        // Propagate types for potentially newly added instructions by
        // ApplyClassIds(). Must occur before canonicalization.
        FlowGraphTypePropagator::Propagate(flow_graph);
        DEBUG_ASSERT(flow_graph->VerifyUseLists());

        // Do optimizations that depend on the propagated type information.
        if (flow_graph->Canonicalize()) {
          // Invoke Canonicalize twice in order to fully canonicalize patterns
          // like "if (a & const == 0) { }".
          flow_graph->Canonicalize();
        }
        DEBUG_ASSERT(flow_graph->VerifyUseLists());

        {
#ifndef PRODUCT
          TimelineDurationScope tds2(thread(),
                                     compiler_timeline,
                                     "BranchSimplifier");
#endif  // !PRODUCT
          BranchSimplifier::Simplify(flow_graph);
          DEBUG_ASSERT(flow_graph->VerifyUseLists());

          IfConverter::Simplify(flow_graph);
          DEBUG_ASSERT(flow_graph->VerifyUseLists());
        }

        if (FLAG_constant_propagation) {
#ifndef PRODUCT
          TimelineDurationScope tds2(thread(),
                                     compiler_timeline,
                                     "ConstantPropagation");
#endif  // !PRODUCT
          ConstantPropagator::Optimize(flow_graph);
          DEBUG_ASSERT(flow_graph->VerifyUseLists());
          // A canonicalization pass to remove e.g. smi checks on smi constants.
          flow_graph->Canonicalize();
          DEBUG_ASSERT(flow_graph->VerifyUseLists());
          // Canonicalization introduced more opportunities for constant
          // propagation.
          ConstantPropagator::Optimize(flow_graph);
          DEBUG_ASSERT(flow_graph->VerifyUseLists());
        }

        // Optimistically convert loop phis that have a single non-smi input
        // coming from the loop pre-header into smi-phis.
        if (FLAG_loop_invariant_code_motion) {
          LICM licm(flow_graph);
          licm.OptimisticallySpecializeSmiPhis();
          DEBUG_ASSERT(flow_graph->VerifyUseLists());
        }

        // Propagate types and eliminate even more type tests.
        // Recompute types after constant propagation to infer more precise
        // types for uses that were previously reached by now eliminated phis.
        FlowGraphTypePropagator::Propagate(flow_graph);
        DEBUG_ASSERT(flow_graph->VerifyUseLists());

        {
#ifndef PRODUCT
          TimelineDurationScope tds2(thread(),
                                     compiler_timeline,
                                     "SelectRepresentations");
#endif  // !PRODUCT
          // Where beneficial convert Smi operations into Int32 operations.
          // Only meanigful for 32bit platforms right now.
          flow_graph->WidenSmiToInt32();

          // Unbox doubles. Performed after constant propagation to minimize
          // interference from phis merging double values and tagged
          // values coming from dead paths.
          flow_graph->SelectRepresentations();
          DEBUG_ASSERT(flow_graph->VerifyUseLists());
        }

        {
#ifndef PRODUCT
          TimelineDurationScope tds2(thread(),
                                     compiler_timeline,
                                     "CommonSubexpressionElinination");
#endif  // !PRODUCT
          if (FLAG_common_subexpression_elimination ||
              FLAG_loop_invariant_code_motion) {
            flow_graph->ComputeBlockEffects();
          }

          if (FLAG_common_subexpression_elimination) {
            if (DominatorBasedCSE::Optimize(flow_graph)) {
              DEBUG_ASSERT(flow_graph->VerifyUseLists());
              flow_graph->Canonicalize();
              // Do another round of CSE to take secondary effects into account:
              // e.g. when eliminating dependent loads (a.x[0] + a.x[0])
              // TODO(fschneider): Change to a one-pass optimization pass.
              if (DominatorBasedCSE::Optimize(flow_graph)) {
                flow_graph->Canonicalize();
              }
              DEBUG_ASSERT(flow_graph->VerifyUseLists());
            }
          }

          // Run loop-invariant code motion right after load elimination since
          // it depends on the numbering of loads from the previous
          // load-elimination.
          if (FLAG_loop_invariant_code_motion) {
            LICM licm(flow_graph);
            licm.Optimize();
            DEBUG_ASSERT(flow_graph->VerifyUseLists());
          }
          flow_graph->RemoveRedefinitions();
        }

        // Optimize (a << b) & c patterns, merge operations.
        // Run after CSE in order to have more opportunity to merge
        // instructions that have same inputs.
        flow_graph->TryOptimizePatterns();
        DEBUG_ASSERT(flow_graph->VerifyUseLists());

        {
#ifndef PRODUCT
          TimelineDurationScope tds2(thread(),
                                     compiler_timeline,
                                     "DeadStoreElimination");
#endif  // !PRODUCT
          DeadStoreElimination::Optimize(flow_graph);
        }

        if (FLAG_range_analysis) {
#ifndef PRODUCT
          TimelineDurationScope tds2(thread(),
                                     compiler_timeline,
                                     "RangeAnalysis");
#endif  // !PRODUCT
          // Propagate types after store-load-forwarding. Some phis may have
          // become smi phis that can be processed by range analysis.
          FlowGraphTypePropagator::Propagate(flow_graph);
          DEBUG_ASSERT(flow_graph->VerifyUseLists());

          // We have to perform range analysis after LICM because it
          // optimistically moves CheckSmi through phis into loop preheaders
          // making some phis smi.
          RangeAnalysis range_analysis(flow_graph);
          range_analysis.Analyze();
          DEBUG_ASSERT(flow_graph->VerifyUseLists());
        }

        if (FLAG_constant_propagation) {
#ifndef PRODUCT
          TimelineDurationScope tds2(thread(),
                                     compiler_timeline,
                                     "ConstantPropagator::OptimizeBranches");
#endif  // !PRODUCT
          // Constant propagation can use information from range analysis to
          // find unreachable branch targets and eliminate branches that have
          // the same true- and false-target.
          ConstantPropagator::OptimizeBranches(flow_graph);
          DEBUG_ASSERT(flow_graph->VerifyUseLists());
        }

        // Recompute types after code movement was done to ensure correct
        // reaching types for hoisted values.
        FlowGraphTypePropagator::Propagate(flow_graph);
        DEBUG_ASSERT(flow_graph->VerifyUseLists());

        {
#ifndef PRODUCT
          TimelineDurationScope tds2(thread(),
                                     compiler_timeline,
                                     "TryCatchAnalyzer::Optimize");
#endif  // !PRODUCT
          // Optimize try-blocks.
          TryCatchAnalyzer::Optimize(flow_graph);
        }

        // Detach environments from the instructions that can't deoptimize.
        // Do it before we attempt to perform allocation sinking to minimize
        // amount of materializations it has to perform.
        flow_graph->EliminateEnvironments();

        {
#ifndef PRODUCT
          TimelineDurationScope tds2(thread(),
                                     compiler_timeline,
                                     "EliminateDeadPhis");
#endif  // !PRODUCT
          DeadCodeElimination::EliminateDeadPhis(flow_graph);
          DEBUG_ASSERT(flow_graph->VerifyUseLists());
        }

        if (flow_graph->Canonicalize()) {
          flow_graph->Canonicalize();
        }

        // Attempt to sink allocations of temporary non-escaping objects to
        // the deoptimization path.
        AllocationSinking* sinking = NULL;
        if (FLAG_allocation_sinking &&
            (flow_graph->graph_entry()->SuccessorCount()  == 1)) {
#ifndef PRODUCT
          TimelineDurationScope tds2(thread(),
                                     compiler_timeline,
                                     "AllocationSinking::Optimize");
#endif  // !PRODUCT
          // TODO(fschneider): Support allocation sinking with try-catch.
          sinking = new AllocationSinking(flow_graph);
          sinking->Optimize();
        }
        DEBUG_ASSERT(flow_graph->VerifyUseLists());

        DeadCodeElimination::EliminateDeadPhis(flow_graph);
        DEBUG_ASSERT(flow_graph->VerifyUseLists());

        FlowGraphTypePropagator::Propagate(flow_graph);
        DEBUG_ASSERT(flow_graph->VerifyUseLists());

        {
#ifndef PRODUCT
          TimelineDurationScope tds2(thread(),
                                     compiler_timeline,
                                     "SelectRepresentations");
#endif  // !PRODUCT
          // Ensure that all phis inserted by optimization passes have
          // consistent representations.
          flow_graph->SelectRepresentations();
        }

        if (flow_graph->Canonicalize()) {
          // To fully remove redundant boxing (e.g. BoxDouble used only in
          // environments and UnboxDouble instructions) instruction we
          // first need to replace all their uses and then fold them away.
          // For now we just repeat Canonicalize twice to do that.
          // TODO(vegorov): implement a separate representation folding pass.
          flow_graph->Canonicalize();
        }
        DEBUG_ASSERT(flow_graph->VerifyUseLists());

        if (sinking != NULL) {
#ifndef PRODUCT
          TimelineDurationScope tds2(
              thread(),
              compiler_timeline,
              "AllocationSinking::DetachMaterializations");
#endif  // !PRODUCT
          // Remove all MaterializeObject instructions inserted by allocation
          // sinking from the flow graph and let them float on the side
          // referenced only from environments. Register allocator will consider
          // them as part of a deoptimization environment.
          sinking->DetachMaterializations();
        }

        // Replace bounds check instruction with a generic one.
        optimizer.ReplaceArrayBoundChecks();

        // Compute and store graph informations (call & instruction counts)
        // to be later used by the inliner.
        FlowGraphInliner::CollectGraphInfo(flow_graph, true);

        {
#ifndef PRODUCT
          TimelineDurationScope tds2(thread(),
                                     compiler_timeline,
                                     "AllocateRegisters");
#endif  // !PRODUCT
          // Perform register allocation on the SSA graph.
          FlowGraphAllocator allocator(*flow_graph);
          allocator.AllocateRegisters();
        }

        if (print_flow_graph) {
          FlowGraphPrinter::PrintGraph("After Optimizations", flow_graph);
        }
      }

      ASSERT(inline_id_to_function.length() == caller_inline_id.length());
      Assembler assembler(use_far_branches);
      FlowGraphCompiler graph_compiler(&assembler, flow_graph,
                                       *parsed_function(), optimized(),
                                       inline_id_to_function,
                                       inline_id_to_token_pos,
                                       caller_inline_id);
      {
        CSTAT_TIMER_SCOPE(thread(), graphcompiler_timer);
#ifndef PRODUCT
        TimelineDurationScope tds(thread(),
                                  compiler_timeline,
                                  "CompileGraph");
#endif  // !PRODUCT
        graph_compiler.CompileGraph();
        pipeline->FinalizeCompilation(flow_graph);
      }
      {
#ifndef PRODUCT
        TimelineDurationScope tds(thread(),
                                  compiler_timeline,
                                  "FinalizeCompilation");
#endif  // !PRODUCT
        ASSERT(thread()->IsMutatorThread());
        FinalizeCompilation(&assembler, &graph_compiler, flow_graph);
      }
      // Mark that this isolate now has compiled code.
      isolate()->set_has_compiled_code(true);
      // Exit the loop and the function with the correct result value.
      is_compiled = true;
      done = true;
    } else {
      // We bailed out or we encountered an error.
      const Error& error = Error::Handle(thread()->sticky_error());

      if (error.raw() == Object::branch_offset_error().raw()) {
        // Compilation failed due to an out of range branch offset in the
        // assembler. We try again (done = false) with far branches enabled.
        done = false;
        ASSERT(!use_far_branches);
        use_far_branches = true;
      } else if (error.raw() == Object::speculative_inlining_error().raw()) {
        // The return value of setjmp is the deopt id of the check instruction
        // that caused the bailout.
        done = false;
        if (!use_speculative_inlining) {
          // Assert that we don't repeatedly retry speculation.
          UNREACHABLE();
        }
#if defined(DEBUG)
        for (intptr_t i = 0; i < inlining_black_list.length(); ++i) {
          ASSERT(inlining_black_list[i] != val);
        }
#endif
        inlining_black_list.Add(val);
        const intptr_t max_attempts = FLAG_max_speculative_inlining_attempts;
        if (inlining_black_list.length() >= max_attempts) {
          use_speculative_inlining = false;
          if (FLAG_trace_compiler || FLAG_trace_optimizing_compiler) {
            THR_Print("Disabled speculative inlining after %" Pd " attempts.\n",
                      inlining_black_list.length());
          }
        }
      } else {
        // If the error isn't due to an out of range branch offset, we don't
        // try again (done = true), and indicate that we did not finish
        // compiling (is_compiled = false).
        if (FLAG_trace_bailout) {
          THR_Print("%s\n", error.ToErrorCString());
        }
        done = true;
      }

      // Clear the error if it was not a real error, but just a bailout.
      if (error.IsLanguageError() &&
          (LanguageError::Cast(error).kind() == Report::kBailout)) {
        thread()->clear_sticky_error();
      }
      is_compiled = false;
    }
    // Reset global isolate state.
    thread()->set_deopt_id(prev_deopt_id);
  }
  return is_compiled;
}


static RawError* PrecompileFunctionHelper(Precompiler* precompiler,
                                          CompilationPipeline* pipeline,
                                          const Function& function,
                                          bool optimized) {
  // Check that we optimize, except if the function is not optimizable.
  ASSERT(FLAG_precompiled_mode);
  ASSERT(!function.IsOptimizable() || optimized);
  ASSERT(!function.HasCode());
  LongJumpScope jump;
  if (setjmp(*jump.Set()) == 0) {
    Thread* const thread = Thread::Current();
    StackZone stack_zone(thread);
    Zone* const zone = stack_zone.GetZone();
    const bool trace_compiler =
        FLAG_trace_compiler ||
        (FLAG_trace_optimizing_compiler && optimized);
    Timer per_compile_timer(trace_compiler, "Compilation time");
    per_compile_timer.Start();

    ParsedFunction* parsed_function = new(zone) ParsedFunction(
        thread, Function::ZoneHandle(zone, function.raw()));
    if (trace_compiler) {
      THR_Print(
          "Precompiling %sfunction: '%s' @ token %" Pd ", size %" Pd "\n",
          (optimized ? "optimized " : ""),
          function.ToFullyQualifiedCString(),
          function.token_pos().Pos(),
          (function.end_token_pos().Pos() - function.token_pos().Pos()));
    }
    INC_STAT(thread, num_functions_compiled, 1);
    if (optimized) {
      INC_STAT(thread, num_functions_optimized, 1);
    }
    {
      HANDLESCOPE(thread);
      const int64_t num_tokens_before = STAT_VALUE(thread, num_tokens_consumed);
      pipeline->ParseFunction(parsed_function);
      const int64_t num_tokens_after = STAT_VALUE(thread, num_tokens_consumed);
      INC_STAT(thread,
               num_func_tokens_compiled,
               num_tokens_after - num_tokens_before);
    }

    PrecompileParsedFunctionHelper helper(
        precompiler, parsed_function, optimized);
    const bool success = helper.Compile(pipeline);
    if (!success) {
      // Encountered error.
      Error& error = Error::Handle();
      // We got an error during compilation.
      error = thread->sticky_error();
      thread->clear_sticky_error();
      ASSERT(error.IsLanguageError() &&
             LanguageError::Cast(error).kind() != Report::kBailout);
      return error.raw();
    }

    per_compile_timer.Stop();

    if (trace_compiler) {
      THR_Print("--> '%s' entry: %#" Px " size: %" Pd " time: %" Pd64 " us\n",
                function.ToFullyQualifiedCString(),
                Code::Handle(function.CurrentCode()).PayloadStart(),
                Code::Handle(function.CurrentCode()).Size(),
                per_compile_timer.TotalElapsedTime());
    }

    if (FLAG_disassemble && FlowGraphPrinter::ShouldPrint(function)) {
      Disassembler::DisassembleCode(function, optimized);
    } else if (FLAG_disassemble_optimized &&
               optimized &&
               FlowGraphPrinter::ShouldPrint(function)) {
      Disassembler::DisassembleCode(function, true);
    }
    return Error::null();
  } else {
    Thread* const thread = Thread::Current();
    StackZone stack_zone(thread);
    Error& error = Error::Handle();
    // We got an error during compilation.
    error = thread->sticky_error();
    thread->clear_sticky_error();
    // Precompilation may encounter compile-time errors.
    // Do not attempt to optimize functions that can cause errors.
    function.set_is_optimizable(false);
    return error.raw();
  }
  UNREACHABLE();
  return Error::null();
}


RawError* Precompiler::CompileFunction(Precompiler* precompiler,
                                       Thread* thread,
                                       Zone* zone,
                                       const Function& function,
                                       FieldTypeMap* field_type_map) {
  VMTagScope tagScope(thread, VMTag::kCompileUnoptimizedTagId);
  TIMELINE_FUNCTION_COMPILATION_DURATION(thread, "CompileFunction", function);

  ASSERT(FLAG_precompiled_mode);
  const bool optimized = function.IsOptimizable();  // False for natives.
  DartPrecompilationPipeline pipeline(zone, field_type_map);
  return PrecompileFunctionHelper(precompiler, &pipeline, function, optimized);
}

#endif  // DART_PRECOMPILER

}  // namespace dart