// Copyright (c) 2013, 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/compiler/backend/flow_graph_compiler.h"
#include "vm/globals.h"  // Needed here to get TARGET_ARCH_XXX.

#include "platform/utils.h"
#include "vm/bit_vector.h"
#include "vm/compiler/backend/code_statistics.h"
#include "vm/compiler/backend/il_printer.h"
#include "vm/compiler/backend/inliner.h"
#include "vm/compiler/backend/linearscan.h"
#include "vm/compiler/backend/locations.h"
#include "vm/compiler/backend/loops.h"
#include "vm/compiler/cha.h"
#include "vm/compiler/intrinsifier.h"
#include "vm/compiler/jit/compiler.h"
#include "vm/dart_entry.h"
#include "vm/debugger.h"
#include "vm/deopt_instructions.h"
#include "vm/exceptions.h"
#include "vm/flags.h"
#include "vm/kernel_isolate.h"
#include "vm/log.h"
#include "vm/longjump.h"
#include "vm/object_store.h"
#include "vm/parser.h"
#include "vm/raw_object.h"
#include "vm/resolver.h"
#include "vm/service_isolate.h"
#include "vm/stack_frame.h"
#include "vm/stub_code.h"
#include "vm/symbols.h"
#include "vm/timeline.h"
#include "vm/type_testing_stubs.h"

namespace dart {

DEFINE_FLAG(bool,
            trace_inlining_intervals,
            false,
            "Inlining interval diagnostics");

DEFINE_FLAG(bool, enable_peephole, true, "Enable peephole optimization");

#if !defined(DART_PRECOMPILED_RUNTIME)

DEFINE_FLAG(bool,
            enable_simd_inline,
            true,
            "Enable inlining of SIMD related method calls.");
DEFINE_FLAG(int,
            min_optimization_counter_threshold,
            5000,
            "The minimum invocation count for a function.");
DEFINE_FLAG(int,
            optimization_counter_scale,
            2000,
            "The scale of invocation count, by size of the function.");
DEFINE_FLAG(bool, source_lines, false, "Emit source line as assembly comment.");

DECLARE_FLAG(bool, code_comments);
DECLARE_FLAG(charp, deoptimize_filter);
DECLARE_FLAG(bool, intrinsify);
DECLARE_FLAG(int, regexp_optimization_counter_threshold);
DECLARE_FLAG(int, reoptimization_counter_threshold);
DECLARE_FLAG(int, stacktrace_every);
DECLARE_FLAG(charp, stacktrace_filter);
DECLARE_FLAG(int, gc_every);
DECLARE_FLAG(bool, trace_compiler);

// Assign locations to incoming arguments, i.e., values pushed above spill slots
// with PushArgument.  Recursively allocates from outermost to innermost
// environment.
void CompilerDeoptInfo::AllocateIncomingParametersRecursive(
    Environment* env,
    intptr_t* stack_height) {
  if (env == NULL) return;
  AllocateIncomingParametersRecursive(env->outer(), stack_height);
  for (Environment::ShallowIterator it(env); !it.Done(); it.Advance()) {
    if (it.CurrentLocation().IsInvalid() &&
        it.CurrentValue()->definition()->IsPushArgument()) {
      it.SetCurrentLocation(Location::StackSlot(
          compiler::target::frame_layout.FrameSlotForVariableIndex(
              -*stack_height),
          FPREG));
      (*stack_height)++;
    }
  }
}

void CompilerDeoptInfo::EmitMaterializations(Environment* env,
                                             DeoptInfoBuilder* builder) {
  for (Environment::DeepIterator it(env); !it.Done(); it.Advance()) {
    if (it.CurrentLocation().IsInvalid()) {
      MaterializeObjectInstr* mat =
          it.CurrentValue()->definition()->AsMaterializeObject();
      ASSERT(mat != NULL);
      builder->AddMaterialization(mat);
    }
  }
}

FlowGraphCompiler::FlowGraphCompiler(
    compiler::Assembler* assembler,
    FlowGraph* flow_graph,
    const ParsedFunction& parsed_function,
    bool is_optimizing,
    SpeculativeInliningPolicy* speculative_policy,
    const GrowableArray<const Function*>& inline_id_to_function,
    const GrowableArray<TokenPosition>& inline_id_to_token_pos,
    const GrowableArray<intptr_t>& caller_inline_id,
    ZoneGrowableArray<const ICData*>* deopt_id_to_ic_data,
    CodeStatistics* stats /* = NULL */)
    : thread_(Thread::Current()),
      zone_(Thread::Current()->zone()),
      assembler_(assembler),
      parsed_function_(parsed_function),
      flow_graph_(*flow_graph),
      block_order_(*flow_graph->CodegenBlockOrder(is_optimizing)),
      current_block_(NULL),
      exception_handlers_list_(NULL),
      pc_descriptors_list_(NULL),
      stackmap_table_builder_(NULL),
      code_source_map_builder_(NULL),
      catch_entry_moves_maps_builder_(NULL),
      block_info_(block_order_.length()),
      deopt_infos_(),
      static_calls_target_table_(),
      is_optimizing_(is_optimizing),
      speculative_policy_(speculative_policy),
      may_reoptimize_(false),
      intrinsic_mode_(false),
      stats_(stats),
      double_class_(
          Class::ZoneHandle(isolate()->object_store()->double_class())),
      mint_class_(Class::ZoneHandle(isolate()->object_store()->mint_class())),
      float32x4_class_(
          Class::ZoneHandle(isolate()->object_store()->float32x4_class())),
      float64x2_class_(
          Class::ZoneHandle(isolate()->object_store()->float64x2_class())),
      int32x4_class_(
          Class::ZoneHandle(isolate()->object_store()->int32x4_class())),
      list_class_(Class::ZoneHandle(Library::Handle(Library::CoreLibrary())
                                        .LookupClass(Symbols::List()))),
      parallel_move_resolver_(this),
      pending_deoptimization_env_(NULL),
      deopt_id_to_ic_data_(deopt_id_to_ic_data),
      edge_counters_array_(Array::ZoneHandle()) {
  ASSERT(flow_graph->parsed_function().function().raw() ==
         parsed_function.function().raw());
  if (is_optimizing) {
    // No need to collect extra ICData objects created during compilation.
    deopt_id_to_ic_data_ = nullptr;
  } else {
    const intptr_t len = thread()->compiler_state().deopt_id();
    deopt_id_to_ic_data_->EnsureLength(len, nullptr);
  }
  ASSERT(assembler != NULL);
  ASSERT(!list_class_.IsNull());

#if defined(PRODUCT)
  const bool stack_traces_only = true;
#else
  const bool stack_traces_only = false;
#endif
  code_source_map_builder_ = new (zone_)
      CodeSourceMapBuilder(stack_traces_only, caller_inline_id,
                           inline_id_to_token_pos, inline_id_to_function);

  ArchSpecificInitialization();
}

bool FlowGraphCompiler::IsUnboxedField(const Field& field) {
  bool valid_class =
      (SupportsUnboxedDoubles() && (field.guarded_cid() == kDoubleCid)) ||
      (SupportsUnboxedSimd128() && (field.guarded_cid() == kFloat32x4Cid)) ||
      (SupportsUnboxedSimd128() && (field.guarded_cid() == kFloat64x2Cid));
  return field.is_unboxing_candidate() && !field.is_nullable() && valid_class;
}

bool FlowGraphCompiler::IsPotentialUnboxedField(const Field& field) {
  return field.is_unboxing_candidate() &&
         (FlowGraphCompiler::IsUnboxedField(field) ||
          (field.guarded_cid() == kIllegalCid));
}

void FlowGraphCompiler::InitCompiler() {
  pc_descriptors_list_ = new (zone()) DescriptorList(64);
  exception_handlers_list_ = new (zone()) ExceptionHandlerList();
#if defined(DART_PRECOMPILER)
  catch_entry_moves_maps_builder_ = new (zone()) CatchEntryMovesMapBuilder();
#endif
  block_info_.Clear();
  // Initialize block info and search optimized (non-OSR) code for calls
  // indicating a non-leaf routine and calls without IC data indicating
  // possible reoptimization.

  for (int i = 0; i < block_order_.length(); ++i) {
    block_info_.Add(new (zone()) BlockInfo());
    if (is_optimizing() && !flow_graph().IsCompiledForOsr()) {
      BlockEntryInstr* entry = block_order_[i];
      for (ForwardInstructionIterator it(entry); !it.Done(); it.Advance()) {
        Instruction* current = it.Current();
        if (current->IsBranch()) {
          current = current->AsBranch()->comparison();
        }
        // In optimized code, ICData is always set in the instructions.
        const ICData* ic_data = NULL;
        if (current->IsInstanceCall()) {
          ic_data = current->AsInstanceCall()->ic_data();
        }
        if ((ic_data != NULL) && (ic_data->NumberOfUsedChecks() == 0)) {
          may_reoptimize_ = true;
        }
      }
    }
  }

  if (!is_optimizing() && FLAG_reorder_basic_blocks) {
    // Initialize edge counter array.
    const intptr_t num_counters = flow_graph_.preorder().length();
    const Array& edge_counters =
        Array::Handle(Array::New(num_counters, Heap::kOld));
    const Smi& zero_smi = Smi::Handle(Smi::New(0));
    for (intptr_t i = 0; i < num_counters; ++i) {
      edge_counters.SetAt(i, zero_smi);
    }
    edge_counters_array_ = edge_counters.raw();
  }
}

bool FlowGraphCompiler::CanOptimize() {
  return FLAG_optimization_counter_threshold >= 0;
}

bool FlowGraphCompiler::CanOptimizeFunction() const {
  return CanOptimize() && !parsed_function().function().HasBreakpoint();
}

bool FlowGraphCompiler::CanOSRFunction() const {
  return isolate()->use_osr() && CanOptimizeFunction() && !is_optimizing();
}

bool FlowGraphCompiler::ForceSlowPathForStackOverflow() const {
#if !defined(PRODUCT)
  if ((FLAG_stacktrace_every > 0) || (FLAG_deoptimize_every > 0) ||
      (FLAG_gc_every > 0) ||
      (isolate()->reload_every_n_stack_overflow_checks() > 0)) {
    if (!Isolate::IsVMInternalIsolate(isolate())) {
      return true;
    }
  }
  if (FLAG_stacktrace_filter != NULL &&
      strstr(parsed_function().function().ToFullyQualifiedCString(),
             FLAG_stacktrace_filter) != NULL) {
    return true;
  }
  if (is_optimizing() && FLAG_deoptimize_filter != NULL &&
      strstr(parsed_function().function().ToFullyQualifiedCString(),
             FLAG_deoptimize_filter) != NULL) {
    return true;
  }
#endif  // !defined(PRODUCT)
  return false;
}

bool FlowGraphCompiler::IsEmptyBlock(BlockEntryInstr* block) const {
  // Entry-points cannot be merged because they must have assembly
  // prologue emitted which should not be included in any block they jump to.
  return !block->IsGraphEntry() && !block->IsFunctionEntry() &&
         !block->IsCatchBlockEntry() && !block->IsOsrEntry() &&
         !block->IsIndirectEntry() && !block->HasNonRedundantParallelMove() &&
         block->next()->IsGoto() &&
         !block->next()->AsGoto()->HasNonRedundantParallelMove();
}

void FlowGraphCompiler::CompactBlock(BlockEntryInstr* block) {
  BlockInfo* block_info = block_info_[block->postorder_number()];

  // Break out of cycles in the control flow graph.
  if (block_info->is_marked()) {
    return;
  }
  block_info->mark();

  if (IsEmptyBlock(block)) {
    // For empty blocks, record a corresponding nonempty target as their
    // jump label.
    BlockEntryInstr* target = block->next()->AsGoto()->successor();
    CompactBlock(target);
    block_info->set_jump_label(GetJumpLabel(target));
  }
}

void FlowGraphCompiler::CompactBlocks() {
  // This algorithm does not garbage collect blocks in place, but merely
  // records forwarding label information.  In this way it avoids having to
  // change join and target entries.
  compiler::Label* nonempty_label = NULL;
  for (intptr_t i = block_order().length() - 1; i >= 1; --i) {
    BlockEntryInstr* block = block_order()[i];

    // Unoptimized code must emit all possible deoptimization points.
    if (is_optimizing()) {
      CompactBlock(block);
    }

    // For nonempty blocks, record the next nonempty block in the block
    // order.  Since no code is emitted for empty blocks, control flow is
    // eligible to fall through to the next nonempty one.
    if (!WasCompacted(block)) {
      BlockInfo* block_info = block_info_[block->postorder_number()];
      block_info->set_next_nonempty_label(nonempty_label);
      nonempty_label = GetJumpLabel(block);
    }
  }

  ASSERT(block_order()[0]->IsGraphEntry());
  BlockInfo* block_info = block_info_[block_order()[0]->postorder_number()];
  block_info->set_next_nonempty_label(nonempty_label);
}

intptr_t FlowGraphCompiler::UncheckedEntryOffset() const {
  BlockEntryInstr* entry = flow_graph().graph_entry()->unchecked_entry();
  if (entry == nullptr) {
    entry = flow_graph().graph_entry()->normal_entry();
  }
  if (entry == nullptr) {
    entry = flow_graph().graph_entry()->osr_entry();
  }
  ASSERT(entry != nullptr);
  compiler::Label* target = GetJumpLabel(entry);

  if (target->IsBound()) {
    return target->Position();
  }

  // Intrinsification happened.
  if (parsed_function().function().IsDynamicFunction()) {
    return FLAG_precompiled_mode ? Instructions::kPolymorphicEntryOffsetAOT
                                 : Instructions::kPolymorphicEntryOffsetJIT;
  }

  return 0;
}

#if defined(DART_PRECOMPILER)
static intptr_t LocationToStackIndex(const Location& src) {
  ASSERT(src.HasStackIndex());
  return -compiler::target::frame_layout.VariableIndexForFrameSlot(
      src.stack_index());
}

static CatchEntryMove CatchEntryMoveFor(compiler::Assembler* assembler,
                                        Representation src_rep,
                                        const Location& src,
                                        intptr_t dst_index) {
  if (src.IsConstant()) {
    // Skip dead locations.
    if (src.constant().raw() == Symbols::OptimizedOut().raw()) {
      return CatchEntryMove();
    }
    const intptr_t pool_index =
        assembler->object_pool_builder().FindObject(src.constant());
    return CatchEntryMove::FromSlot(CatchEntryMove::SourceKind::kConstant,
                                    pool_index, dst_index);
  }

  if (src.IsPairLocation()) {
    const auto lo_loc = src.AsPairLocation()->At(0);
    const auto hi_loc = src.AsPairLocation()->At(1);
    ASSERT(lo_loc.IsStackSlot() && hi_loc.IsStackSlot());
    return CatchEntryMove::FromSlot(
        CatchEntryMove::SourceKind::kInt64PairSlot,
        CatchEntryMove::EncodePairSource(LocationToStackIndex(lo_loc),
                                         LocationToStackIndex(hi_loc)),
        dst_index);
  }

  CatchEntryMove::SourceKind src_kind;
  switch (src_rep) {
    case kTagged:
      src_kind = CatchEntryMove::SourceKind::kTaggedSlot;
      break;
    case kUnboxedInt64:
      src_kind = CatchEntryMove::SourceKind::kInt64Slot;
      break;
    case kUnboxedInt32:
      src_kind = CatchEntryMove::SourceKind::kInt32Slot;
      break;
    case kUnboxedUint32:
      src_kind = CatchEntryMove::SourceKind::kUint32Slot;
      break;
    case kUnboxedDouble:
      src_kind = CatchEntryMove::SourceKind::kDoubleSlot;
      break;
    case kUnboxedFloat32x4:
      src_kind = CatchEntryMove::SourceKind::kFloat32x4Slot;
      break;
    case kUnboxedFloat64x2:
      src_kind = CatchEntryMove::SourceKind::kFloat64x2Slot;
      break;
    case kUnboxedInt32x4:
      src_kind = CatchEntryMove::SourceKind::kInt32x4Slot;
      break;
    default:
      UNREACHABLE();
      break;
  }

  return CatchEntryMove::FromSlot(src_kind, LocationToStackIndex(src),
                                  dst_index);
}
#endif

void FlowGraphCompiler::RecordCatchEntryMoves(Environment* env,
                                              intptr_t try_index) {
#if defined(DART_PRECOMPILER)
  env = env ? env : pending_deoptimization_env_;
  try_index = try_index != kInvalidTryIndex ? try_index : CurrentTryIndex();
  if (is_optimizing() && env != nullptr && (try_index != kInvalidTryIndex)) {
    env = env->Outermost();
    CatchBlockEntryInstr* catch_block =
        flow_graph().graph_entry()->GetCatchEntry(try_index);
    const GrowableArray<Definition*>* idefs =
        catch_block->initial_definitions();
    catch_entry_moves_maps_builder_->NewMapping(assembler()->CodeSize());

    const intptr_t num_direct_parameters = flow_graph().num_direct_parameters();
    const intptr_t ex_idx =
        catch_block->raw_exception_var() != nullptr
            ? flow_graph().EnvIndex(catch_block->raw_exception_var())
            : -1;
    const intptr_t st_idx =
        catch_block->raw_stacktrace_var() != nullptr
            ? flow_graph().EnvIndex(catch_block->raw_stacktrace_var())
            : -1;
    for (intptr_t i = 0; i < flow_graph().variable_count(); ++i) {
      // Don't sync captured parameters. They are not in the environment.
      if (flow_graph().captured_parameters()->Contains(i)) continue;
      // Don't sync exception or stack trace variables.
      if (i == ex_idx || i == st_idx) continue;
      // Don't sync values that have been replaced with constants.
      if ((*idefs)[i]->IsConstant()) continue;

      Location src = env->LocationAt(i);
      // Can only occur if AllocationSinking is enabled - and it is disabled
      // in functions with try.
      ASSERT(!src.IsInvalid());
      const Representation src_rep =
          env->ValueAt(i)->definition()->representation();
      intptr_t dest_index = i - num_direct_parameters;
      const auto move =
          CatchEntryMoveFor(assembler(), src_rep, src, dest_index);
      if (!move.IsRedundant()) {
        catch_entry_moves_maps_builder_->Append(move);
      }
    }

    catch_entry_moves_maps_builder_->EndMapping();
  }
#endif  // defined(DART_PRECOMPILER) || defined(DART_PRECOMPILED_RUNTIME)
}

void FlowGraphCompiler::EmitCallsiteMetadata(TokenPosition token_pos,
                                             intptr_t deopt_id,
                                             RawPcDescriptors::Kind kind,
                                             LocationSummary* locs,
                                             Environment* env) {
  AddCurrentDescriptor(kind, deopt_id, token_pos);
  RecordSafepoint(locs);
  RecordCatchEntryMoves(env);
  if (deopt_id != DeoptId::kNone) {
    // Marks either the continuation point in unoptimized code or the
    // deoptimization point in optimized code, after call.
    const intptr_t deopt_id_after = DeoptId::ToDeoptAfter(deopt_id);
    if (is_optimizing()) {
      AddDeoptIndexAtCall(deopt_id_after);
    } else {
      // Add deoptimization continuation point after the call and before the
      // arguments are removed.
      AddCurrentDescriptor(RawPcDescriptors::kDeopt, deopt_id_after, token_pos);
    }
  }
}

void FlowGraphCompiler::EmitInstructionPrologue(Instruction* instr) {
  if (!is_optimizing()) {
    if (instr->CanBecomeDeoptimizationTarget() && !instr->IsGoto()) {
      // Instructions that can be deoptimization targets need to record kDeopt
      // PcDescriptor corresponding to their deopt id. GotoInstr records its
      // own so that it can control the placement.
      AddCurrentDescriptor(RawPcDescriptors::kDeopt, instr->deopt_id(),
                           instr->token_pos());
    }
    AllocateRegistersLocally(instr);
  }
}

void FlowGraphCompiler::EmitSourceLine(Instruction* instr) {
  if (!instr->token_pos().IsReal() || (instr->env() == NULL)) {
    return;
  }
  const Script& script =
      Script::Handle(zone(), instr->env()->function().script());
  intptr_t line_nr;
  intptr_t column_nr;
  script.GetTokenLocation(instr->token_pos(), &line_nr, &column_nr);
  const String& line = String::Handle(zone(), script.GetLine(line_nr));
  assembler()->Comment("Line %" Pd " in '%s':\n           %s", line_nr,
                       instr->env()->function().ToFullyQualifiedCString(),
                       line.ToCString());
}

#if !defined(TARGET_ARCH_DBC)

static bool IsPusher(Instruction* instr) {
  if (auto def = instr->AsDefinition()) {
    return def->HasTemp();
  }
  return false;
}

static bool IsPopper(Instruction* instr) {
  // TODO(ajcbik): even allow deopt targets by making environment aware?
  if (!instr->CanBecomeDeoptimizationTarget()) {
    return !instr->IsPushArgument() && instr->ArgumentCount() == 0 &&
           instr->InputCount() > 0;
  }
  return false;
}

#endif

bool FlowGraphCompiler::IsPeephole(Instruction* instr) const {
#if !defined(TARGET_ARCH_DBC)
  if (FLAG_enable_peephole && !is_optimizing()) {
    return IsPusher(instr) && IsPopper(instr->next());
  }
#endif
  return false;
}

void FlowGraphCompiler::VisitBlocks() {
  CompactBlocks();
  if (compiler::Assembler::EmittingComments()) {
    // The loop_info fields were cleared, recompute.
    flow_graph().ComputeLoops();
  }

  // In precompiled mode, we require the function entry to come first (after the
  // graph entry), since the polymorphic check is performed in the function
  // entry (see Instructions::EntryPoint).
  if (FLAG_precompiled_mode) {
    ASSERT(block_order()[1] == flow_graph().graph_entry()->normal_entry());
  }

  for (intptr_t i = 0; i < block_order().length(); ++i) {
    // Compile the block entry.
    BlockEntryInstr* entry = block_order()[i];
    assembler()->Comment("B%" Pd "", entry->block_id());
    set_current_block(entry);

    if (WasCompacted(entry)) {
      continue;
    }

#if defined(DEBUG) && !defined(TARGET_ARCH_DBC)
    if (!is_optimizing()) {
      FrameStateClear();
    }
#endif

    if (compiler::Assembler::EmittingComments()) {
      for (LoopInfo* l = entry->loop_info(); l != nullptr; l = l->outer()) {
        assembler()->Comment("  Loop %" Pd "", l->id());
      }
    }

    entry->set_offset(assembler()->CodeSize());
    BeginCodeSourceRange();
    ASSERT(pending_deoptimization_env_ == NULL);
    pending_deoptimization_env_ = entry->env();
    StatsBegin(entry);
    entry->EmitNativeCode(this);
    StatsEnd(entry);
    pending_deoptimization_env_ = NULL;
    EndCodeSourceRange(entry->token_pos());

    if (skip_body_compilation()) {
      ASSERT(entry == flow_graph().graph_entry()->normal_entry());
      break;
    }

    // Compile all successors until an exit, branch, or a block entry.
    for (ForwardInstructionIterator it(entry); !it.Done(); it.Advance()) {
      Instruction* instr = it.Current();
      StatsBegin(instr);
      // Compose intervals.
      code_source_map_builder_->StartInliningInterval(assembler()->CodeSize(),
                                                      instr->inlining_id());
      if (FLAG_code_comments || FLAG_disassemble ||
          FLAG_disassemble_optimized) {
        if (FLAG_source_lines) {
          EmitSourceLine(instr);
        }
        EmitComment(instr);
      }
      if (instr->IsParallelMove()) {
        parallel_move_resolver_.EmitNativeCode(instr->AsParallelMove());
      } else {
        BeginCodeSourceRange();
        EmitInstructionPrologue(instr);
        ASSERT(pending_deoptimization_env_ == NULL);
        pending_deoptimization_env_ = instr->env();
        instr->EmitNativeCode(this);
        pending_deoptimization_env_ = NULL;
        if (IsPeephole(instr)) {
          ASSERT(top_of_stack_ == nullptr);
          top_of_stack_ = instr->AsDefinition();
        } else {
          EmitInstructionEpilogue(instr);
        }
        EndCodeSourceRange(instr->token_pos());
      }

#if defined(DEBUG) && !defined(TARGET_ARCH_DBC)
      if (!is_optimizing()) {
        FrameStateUpdateWith(instr);
      }
#endif
      StatsEnd(instr);
    }

#if defined(DEBUG) && !defined(TARGET_ARCH_DBC)
    ASSERT(is_optimizing() || FrameStateIsSafeToCall());
#endif
  }

  set_current_block(NULL);
}

void FlowGraphCompiler::Bailout(const char* reason) {
  parsed_function_.Bailout("FlowGraphCompiler", reason);
}

intptr_t FlowGraphCompiler::StackSize() const {
  if (is_optimizing_) {
    return flow_graph_.graph_entry()->spill_slot_count();
  } else {
    return parsed_function_.num_stack_locals();
  }
}

intptr_t FlowGraphCompiler::ExtraStackSlotsOnOsrEntry() const {
  ASSERT(flow_graph().IsCompiledForOsr());
  const intptr_t stack_depth =
      flow_graph().graph_entry()->osr_entry()->stack_depth();
  const intptr_t num_stack_locals = flow_graph().num_stack_locals();
  return StackSize() - stack_depth - num_stack_locals;
}

compiler::Label* FlowGraphCompiler::GetJumpLabel(
    BlockEntryInstr* block_entry) const {
  const intptr_t block_index = block_entry->postorder_number();
  return block_info_[block_index]->jump_label();
}

bool FlowGraphCompiler::WasCompacted(BlockEntryInstr* block_entry) const {
  const intptr_t block_index = block_entry->postorder_number();
  return block_info_[block_index]->WasCompacted();
}

compiler::Label* FlowGraphCompiler::NextNonEmptyLabel() const {
  const intptr_t current_index = current_block()->postorder_number();
  return block_info_[current_index]->next_nonempty_label();
}

bool FlowGraphCompiler::CanFallThroughTo(BlockEntryInstr* block_entry) const {
  return NextNonEmptyLabel() == GetJumpLabel(block_entry);
}

BranchLabels FlowGraphCompiler::CreateBranchLabels(BranchInstr* branch) const {
  compiler::Label* true_label = GetJumpLabel(branch->true_successor());
  compiler::Label* false_label = GetJumpLabel(branch->false_successor());
  compiler::Label* fall_through = NextNonEmptyLabel();
  BranchLabels result = {true_label, false_label, fall_through};
  return result;
}

void FlowGraphCompiler::AddSlowPathCode(SlowPathCode* code) {
  slow_path_code_.Add(code);
}

void FlowGraphCompiler::GenerateDeferredCode() {
  for (intptr_t i = 0; i < slow_path_code_.length(); i++) {
    SlowPathCode* const slow_path = slow_path_code_[i];
    const CombinedCodeStatistics::EntryCounter stats_tag =
        CombinedCodeStatistics::SlowPathCounterFor(
            slow_path->instruction()->tag());
    SpecialStatsBegin(stats_tag);
    BeginCodeSourceRange();
    slow_path->GenerateCode(this);
    EndCodeSourceRange(slow_path->instruction()->token_pos());
    SpecialStatsEnd(stats_tag);
  }
  for (intptr_t i = 0; i < deopt_infos_.length(); i++) {
    BeginCodeSourceRange();
    deopt_infos_[i]->GenerateCode(this, i);
    EndCodeSourceRange(TokenPosition::kDeferredDeoptInfo);
  }
}

void FlowGraphCompiler::AddExceptionHandler(intptr_t try_index,
                                            intptr_t outer_try_index,
                                            intptr_t pc_offset,
                                            TokenPosition token_pos,
                                            bool is_generated,
                                            const Array& handler_types,
                                            bool needs_stacktrace) {
  exception_handlers_list_->AddHandler(try_index, outer_try_index, pc_offset,
                                       token_pos, is_generated, handler_types,
                                       needs_stacktrace);
}

void FlowGraphCompiler::SetNeedsStackTrace(intptr_t try_index) {
  exception_handlers_list_->SetNeedsStackTrace(try_index);
}

void FlowGraphCompiler::AddDescriptor(RawPcDescriptors::Kind kind,
                                      intptr_t pc_offset,
                                      intptr_t deopt_id,
                                      TokenPosition token_pos,
                                      intptr_t try_index) {
  code_source_map_builder_->NoteDescriptor(kind, pc_offset, token_pos);
  // Don't emit deopt-descriptors in AOT mode.
  if (FLAG_precompiled_mode && (kind == RawPcDescriptors::kDeopt)) return;
  pc_descriptors_list_->AddDescriptor(kind, pc_offset, deopt_id, token_pos,
                                      try_index);
}

// Uses current pc position and try-index.
void FlowGraphCompiler::AddCurrentDescriptor(RawPcDescriptors::Kind kind,
                                             intptr_t deopt_id,
                                             TokenPosition token_pos) {
  AddDescriptor(kind, assembler()->CodeSize(), deopt_id, token_pos,
                CurrentTryIndex());
}

void FlowGraphCompiler::AddNullCheck(intptr_t pc_offset,
                                     TokenPosition token_pos,
                                     intptr_t null_check_name_idx) {
  code_source_map_builder_->NoteNullCheck(pc_offset, token_pos,
                                          null_check_name_idx);
}

void FlowGraphCompiler::AddPcRelativeCallTarget(const Function& function,
                                                Code::EntryKind entry_kind) {
  ASSERT(function.IsZoneHandle());
  const auto entry_point = entry_kind == Code::EntryKind::kUnchecked
                               ? Code::kUncheckedEntry
                               : Code::kDefaultEntry;
  static_calls_target_table_.Add(
      new (zone()) StaticCallsStruct(Code::kPcRelativeCall, entry_point,
                                     assembler()->CodeSize(), &function, NULL));
}

void FlowGraphCompiler::AddPcRelativeCallStubTarget(const Code& stub_code) {
  ASSERT(stub_code.IsZoneHandle() || stub_code.IsReadOnlyHandle());
  ASSERT(!stub_code.IsNull());
  static_calls_target_table_.Add(new (zone()) StaticCallsStruct(
      Code::kPcRelativeCall, Code::kDefaultEntry, assembler()->CodeSize(), NULL,
      &stub_code));
}

void FlowGraphCompiler::AddStaticCallTarget(const Function& func,
                                            Code::EntryKind entry_kind) {
  ASSERT(func.IsZoneHandle());
  const auto entry_point = entry_kind == Code::EntryKind::kUnchecked
                               ? Code::kUncheckedEntry
                               : Code::kDefaultEntry;
  static_calls_target_table_.Add(new (zone()) StaticCallsStruct(
      Code::kCallViaCode, entry_point, assembler()->CodeSize(), &func, NULL));
}

void FlowGraphCompiler::AddStubCallTarget(const Code& code) {
  ASSERT(code.IsZoneHandle() || code.IsReadOnlyHandle());
  static_calls_target_table_.Add(
      new (zone()) StaticCallsStruct(Code::kCallViaCode, Code::kDefaultEntry,
                                     assembler()->CodeSize(), NULL, &code));
}

CompilerDeoptInfo* FlowGraphCompiler::AddDeoptIndexAtCall(intptr_t deopt_id) {
  ASSERT(is_optimizing());
  ASSERT(!intrinsic_mode());
  CompilerDeoptInfo* info =
      new (zone()) CompilerDeoptInfo(deopt_id, ICData::kDeoptAtCall,
                                     0,  // No flags.
                                     pending_deoptimization_env_);
  info->set_pc_offset(assembler()->CodeSize());
  deopt_infos_.Add(info);
  return info;
}

CompilerDeoptInfo* FlowGraphCompiler::AddSlowPathDeoptInfo(intptr_t deopt_id,
                                                           Environment* env) {
  ASSERT(deopt_id != DeoptId::kNone);
  CompilerDeoptInfo* info =
      new (zone()) CompilerDeoptInfo(deopt_id, ICData::kDeoptUnknown, 0, env);
  info->set_pc_offset(assembler()->CodeSize());
  deopt_infos_.Add(info);
  return info;
}

// This function must be in sync with FlowGraphCompiler::SaveLiveRegisters
// and FlowGraphCompiler::SlowPathEnvironmentFor.
// See StackFrame::VisitObjectPointers for the details of how stack map is
// interpreted.
void FlowGraphCompiler::RecordSafepoint(LocationSummary* locs,
                                        intptr_t slow_path_argument_count) {
  if (is_optimizing() || locs->live_registers()->HasUntaggedValues()) {
    const intptr_t spill_area_size =
        is_optimizing() ? flow_graph_.graph_entry()->spill_slot_count() : 0;

    RegisterSet* registers = locs->live_registers();
    ASSERT(registers != NULL);
    const intptr_t kFpuRegisterSpillFactor =
        kFpuRegisterSize / compiler::target::kWordSize;
    intptr_t saved_registers_size = 0;
    const bool using_shared_stub = locs->call_on_shared_slow_path();
    if (using_shared_stub) {
      saved_registers_size =
          Utils::CountOneBitsWord(kDartAvailableCpuRegs) +
          (registers->FpuRegisterCount() > 0
               ? kFpuRegisterSpillFactor * kNumberOfFpuRegisters
               : 0) +
          1 /*saved PC*/;
    } else {
      saved_registers_size =
          registers->CpuRegisterCount() +
          (registers->FpuRegisterCount() * kFpuRegisterSpillFactor);
    }

    BitmapBuilder* bitmap = locs->stack_bitmap();

// An instruction may have two safepoints in deferred code. The
// call to RecordSafepoint has the side-effect of appending the live
// registers to the bitmap. This is why the second call to RecordSafepoint
// with the same instruction (and same location summary) sees a bitmap that
// is larger that StackSize(). It will never be larger than StackSize() +
// live_registers_size.
// The first safepoint will grow the bitmap to be the size of
// spill_area_size but the second safepoint will truncate the bitmap and
// append the live registers to it again. The bitmap produced by both calls
// will be the same.
#if !defined(TARGET_ARCH_DBC)
    ASSERT(bitmap->Length() <= (spill_area_size + saved_registers_size));
    bitmap->SetLength(spill_area_size);
#else
    ASSERT(slow_path_argument_count == 0);
    if (bitmap->Length() <= (spill_area_size + saved_registers_size)) {
      bitmap->SetLength(Utils::Maximum(bitmap->Length(), spill_area_size));
    }
#endif

    ASSERT(slow_path_argument_count == 0 || !using_shared_stub);

    // Mark the bits in the stack map in the same order we push registers in
    // slow path code (see FlowGraphCompiler::SaveLiveRegisters).
    //
    // Slow path code can have registers at the safepoint.
    if (!locs->always_calls() && !using_shared_stub) {
      RegisterSet* regs = locs->live_registers();
      if (regs->FpuRegisterCount() > 0) {
        // Denote FPU registers with 0 bits in the stackmap.  Based on the
        // assumption that there are normally few live FPU registers, this
        // encoding is simpler and roughly as compact as storing a separate
        // count of FPU registers.
        //
        // FPU registers have the highest register number at the highest
        // address (i.e., first in the stackmap).
        for (intptr_t i = kNumberOfFpuRegisters - 1; i >= 0; --i) {
          FpuRegister reg = static_cast<FpuRegister>(i);
          if (regs->ContainsFpuRegister(reg)) {
            for (intptr_t j = 0; j < kFpuRegisterSpillFactor; ++j) {
              bitmap->Set(bitmap->Length(), false);
            }
          }
        }
      }

      // General purpose registers have the highest register number at the
      // highest address (i.e., first in the stackmap).
      for (intptr_t i = kNumberOfCpuRegisters - 1; i >= 0; --i) {
        Register reg = static_cast<Register>(i);
        if (locs->live_registers()->ContainsRegister(reg)) {
          bitmap->Set(bitmap->Length(), locs->live_registers()->IsTagged(reg));
        }
      }
    }

    if (using_shared_stub) {
      // To simplify the code in the shared stub, we create an untagged hole
      // in the stack frame where the shared stub can leave the return address
      // before saving registers.
      bitmap->Set(bitmap->Length(), false);
      if (registers->FpuRegisterCount() > 0) {
        bitmap->SetRange(bitmap->Length(),
                         bitmap->Length() +
                             kNumberOfFpuRegisters * kFpuRegisterSpillFactor -
                             1,
                         false);
      }
      for (intptr_t i = kNumberOfCpuRegisters - 1; i >= 0; --i) {
        if ((kReservedCpuRegisters & (1 << i)) != 0) continue;
        const Register reg = static_cast<Register>(i);
        bitmap->Set(bitmap->Length(),
                    locs->live_registers()->ContainsRegister(reg) &&
                        locs->live_registers()->IsTagged(reg));
      }
    }

    // Arguments pushed after live registers in the slow path are tagged.
    for (intptr_t i = 0; i < slow_path_argument_count; ++i) {
      bitmap->Set(bitmap->Length(), true);
    }

    // The slow path area Outside the spill area contains are live registers
    // and pushed arguments for calls inside the slow path.
    intptr_t slow_path_bit_count = bitmap->Length() - spill_area_size;
    stackmap_table_builder()->AddEntry(assembler()->CodeSize(), bitmap,
                                       slow_path_bit_count);
  }
}

// This function must be kept in sync with:
//
//     FlowGraphCompiler::RecordSafepoint
//     FlowGraphCompiler::SaveLiveRegisters
//     MaterializeObjectInstr::RemapRegisters
//
Environment* FlowGraphCompiler::SlowPathEnvironmentFor(
    Instruction* instruction,
    intptr_t num_slow_path_args) {
  const bool using_shared_stub =
      instruction->locs()->call_on_shared_slow_path();
  const bool shared_stub_save_fpu_registers =
      using_shared_stub &&
      instruction->locs()->live_registers()->FpuRegisterCount() > 0;
  // TODO(sjindel): Modify logic below to account for slow-path args with shared
  // stubs.
  ASSERT(!using_shared_stub || num_slow_path_args == 0);
  if (instruction->env() == NULL) {
    ASSERT(!is_optimizing());
    return NULL;
  }

  Environment* env = instruction->env()->DeepCopy(zone());
  // 1. Iterate the registers in the order they will be spilled to compute
  //    the slots they will be spilled to.
  intptr_t next_slot = StackSize() + env->CountArgsPushed();
  if (using_shared_stub) {
    // The PC from the call to the shared stub is pushed here.
    next_slot++;
  }
  RegisterSet* regs = instruction->locs()->live_registers();
  intptr_t fpu_reg_slots[kNumberOfFpuRegisters];
  intptr_t cpu_reg_slots[kNumberOfCpuRegisters];
  const intptr_t kFpuRegisterSpillFactor =
      kFpuRegisterSize / compiler::target::kWordSize;
  // FPU registers are spilled first from highest to lowest register number.
  for (intptr_t i = kNumberOfFpuRegisters - 1; i >= 0; --i) {
    FpuRegister reg = static_cast<FpuRegister>(i);
    if (regs->ContainsFpuRegister(reg)) {
      // We use the lowest address (thus highest index) to identify a
      // multi-word spill slot.
      next_slot += kFpuRegisterSpillFactor;
      fpu_reg_slots[i] = (next_slot - 1);
    } else {
      if (using_shared_stub && shared_stub_save_fpu_registers) {
        next_slot += kFpuRegisterSpillFactor;
      }
      fpu_reg_slots[i] = -1;
    }
  }
  // General purpose registers are spilled from highest to lowest register
  // number.
  for (intptr_t i = kNumberOfCpuRegisters - 1; i >= 0; --i) {
    if ((kReservedCpuRegisters & (1 << i)) != 0) continue;
    Register reg = static_cast<Register>(i);
    if (regs->ContainsRegister(reg)) {
      cpu_reg_slots[i] = next_slot++;
    } else {
      if (using_shared_stub) next_slot++;
      cpu_reg_slots[i] = -1;
    }
  }

  // 2. Iterate the environment and replace register locations with the
  //    corresponding spill slot locations.
  for (Environment::DeepIterator it(env); !it.Done(); it.Advance()) {
    Location loc = it.CurrentLocation();
    Value* value = it.CurrentValue();
    it.SetCurrentLocation(LocationRemapForSlowPath(
        loc, value->definition(), cpu_reg_slots, fpu_reg_slots));
  }

  return env;
}

compiler::Label* FlowGraphCompiler::AddDeoptStub(intptr_t deopt_id,
                                                 ICData::DeoptReasonId reason,
                                                 uint32_t flags) {
  if (intrinsic_mode()) {
    return intrinsic_slow_path_label_;
  }

  // No deoptimization allowed when 'FLAG_precompiled_mode' is set.
  if (FLAG_precompiled_mode) {
    if (FLAG_trace_compiler) {
      THR_Print(
          "Retrying compilation %s, suppressing inlining of deopt_id:%" Pd "\n",
          parsed_function_.function().ToFullyQualifiedCString(), deopt_id);
    }
    ASSERT(speculative_policy_->AllowsSpeculativeInlining());
    ASSERT(deopt_id != 0);  // longjmp must return non-zero value.
    Thread::Current()->long_jump_base()->Jump(
        deopt_id, Object::speculative_inlining_error());
  }

  ASSERT(is_optimizing_);
  CompilerDeoptInfoWithStub* stub = new (zone()) CompilerDeoptInfoWithStub(
      deopt_id, reason, flags, pending_deoptimization_env_);
  deopt_infos_.Add(stub);
  return stub->entry_label();
}

#if defined(TARGET_ARCH_DBC)
void FlowGraphCompiler::EmitDeopt(intptr_t deopt_id,
                                  ICData::DeoptReasonId reason,
                                  uint32_t flags) {
  ASSERT(is_optimizing());
  ASSERT(!intrinsic_mode());
  // The pending deoptimization environment may be changed after this deopt is
  // emitted, so we need to make a copy.
  Environment* env_copy = pending_deoptimization_env_->DeepCopy(zone());
  CompilerDeoptInfo* info =
      new (zone()) CompilerDeoptInfo(deopt_id, reason, flags, env_copy);
  deopt_infos_.Add(info);
  assembler()->Deopt(0, /*is_eager =*/1);
  info->set_pc_offset(assembler()->CodeSize());
}
#endif  // defined(TARGET_ARCH_DBC)

void FlowGraphCompiler::FinalizeExceptionHandlers(const Code& code) {
  ASSERT(exception_handlers_list_ != NULL);
  const ExceptionHandlers& handlers = ExceptionHandlers::Handle(
      exception_handlers_list_->FinalizeExceptionHandlers(code.PayloadStart()));
  code.set_exception_handlers(handlers);
}

void FlowGraphCompiler::FinalizePcDescriptors(const Code& code) {
  ASSERT(pc_descriptors_list_ != NULL);
  const PcDescriptors& descriptors = PcDescriptors::Handle(
      pc_descriptors_list_->FinalizePcDescriptors(code.PayloadStart()));
  if (!is_optimizing_) descriptors.Verify(parsed_function_.function());
  code.set_pc_descriptors(descriptors);
}

RawArray* FlowGraphCompiler::CreateDeoptInfo(compiler::Assembler* assembler) {
  // No deopt information if we precompile (no deoptimization allowed).
  if (FLAG_precompiled_mode) {
    return Array::empty_array().raw();
  }
  // For functions with optional arguments, all incoming arguments are copied
  // to spill slots. The deoptimization environment does not track them.
  const Function& function = parsed_function().function();
  const intptr_t incoming_arg_count =
      function.HasOptionalParameters() ? 0 : function.num_fixed_parameters();
  DeoptInfoBuilder builder(zone(), incoming_arg_count, assembler);

  intptr_t deopt_info_table_size = DeoptTable::SizeFor(deopt_infos_.length());
  if (deopt_info_table_size == 0) {
    return Object::empty_array().raw();
  } else {
    const Array& array =
        Array::Handle(Array::New(deopt_info_table_size, Heap::kOld));
    Smi& offset = Smi::Handle();
    TypedData& info = TypedData::Handle();
    Smi& reason_and_flags = Smi::Handle();
    for (intptr_t i = 0; i < deopt_infos_.length(); i++) {
      offset = Smi::New(deopt_infos_[i]->pc_offset());
      info = deopt_infos_[i]->CreateDeoptInfo(this, &builder, array);
      reason_and_flags = DeoptTable::EncodeReasonAndFlags(
          deopt_infos_[i]->reason(), deopt_infos_[i]->flags());
      DeoptTable::SetEntry(array, i, offset, info, reason_and_flags);
    }
    return array.raw();
  }
}

void FlowGraphCompiler::FinalizeStackMaps(const Code& code) {
  if (stackmap_table_builder_ == NULL) {
    code.set_stackmaps(Object::null_array());
  } else {
    // Finalize the stack map array and add it to the code object.
    code.set_stackmaps(
        Array::Handle(stackmap_table_builder_->FinalizeStackMaps(code)));
  }
}

void FlowGraphCompiler::FinalizeVarDescriptors(const Code& code) {
#if defined(PRODUCT)
// No debugger: no var descriptors.
#else
  if (code.is_optimized()) {
    // Optimized code does not need variable descriptors. They are
    // only stored in the unoptimized version.
    code.set_var_descriptors(Object::empty_var_descriptors());
    return;
  }
  LocalVarDescriptors& var_descs = LocalVarDescriptors::Handle();
  if (flow_graph().IsIrregexpFunction()) {
    // Eager local var descriptors computation for Irregexp function as it is
    // complicated to factor out.
    // TODO(srdjan): Consider canonicalizing and reusing the local var
    // descriptor for IrregexpFunction.
    ASSERT(parsed_function().scope() == nullptr);
    var_descs = LocalVarDescriptors::New(1);
    RawLocalVarDescriptors::VarInfo info;
    info.set_kind(RawLocalVarDescriptors::kSavedCurrentContext);
    info.scope_id = 0;
    info.begin_pos = TokenPosition::kMinSource;
    info.end_pos = TokenPosition::kMinSource;
    info.set_index(compiler::target::frame_layout.FrameSlotForVariable(
        parsed_function().current_context_var()));
    var_descs.SetVar(0, Symbols::CurrentContextVar(), &info);
  }
  code.set_var_descriptors(var_descs);
#endif
}

void FlowGraphCompiler::FinalizeCatchEntryMovesMap(const Code& code) {
#if defined(DART_PRECOMPILER)
  TypedData& maps = TypedData::Handle(
      catch_entry_moves_maps_builder_->FinalizeCatchEntryMovesMap());
  code.set_catch_entry_moves_maps(maps);
#else
  code.set_variables(Smi::Handle(Smi::New(flow_graph().variable_count())));
#endif
}

void FlowGraphCompiler::FinalizeStaticCallTargetsTable(const Code& code) {
  ASSERT(code.static_calls_target_table() == Array::null());
  const auto& calls = static_calls_target_table_;
  const intptr_t array_length = calls.length() * Code::kSCallTableEntryLength;
  const auto& targets =
      Array::Handle(zone(), Array::New(array_length, Heap::kOld));

  StaticCallsTable entries(targets);
  auto& kind_type_and_offset = Smi::Handle(zone());
  for (intptr_t i = 0; i < calls.length(); i++) {
    auto entry = calls[i];
    kind_type_and_offset =
        Smi::New(Code::KindField::encode(entry->call_kind) |
                 Code::EntryPointField::encode(entry->entry_point) |
                 Code::OffsetField::encode(entry->offset));
    auto view = entries[i];
    view.Set<Code::kSCallTableKindAndOffset>(kind_type_and_offset);
    const Object* target = nullptr;
    if (entry->function != nullptr) {
      view.Set<Code::kSCallTableFunctionTarget>(*calls[i]->function);
    }
    if (entry->code != NULL) {
      ASSERT(target == nullptr);
      view.Set<Code::kSCallTableCodeTarget>(*calls[i]->code);
    }
  }
  code.set_static_calls_target_table(targets);
}

void FlowGraphCompiler::FinalizeCodeSourceMap(const Code& code) {
  const Array& inlined_id_array =
      Array::Handle(zone(), code_source_map_builder_->InliningIdToFunction());
  code.set_inlined_id_to_function(inlined_id_array);

  const CodeSourceMap& map =
      CodeSourceMap::Handle(code_source_map_builder_->Finalize());
  code.set_code_source_map(map);

#if defined(DEBUG)
  // Force simulation through the last pc offset. This checks we can decode
  // the whole CodeSourceMap without hitting an unknown opcode, stack underflow,
  // etc.
  GrowableArray<const Function*> fs;
  GrowableArray<TokenPosition> tokens;
  code.GetInlinedFunctionsAtInstruction(code.Size() - 1, &fs, &tokens);
#endif
}

// Returns 'true' if regular code generation should be skipped.
bool FlowGraphCompiler::TryIntrinsify() {
  if (TryIntrinsifyHelper()) {
    fully_intrinsified_ = true;
    return true;
  }
  return false;
}

bool FlowGraphCompiler::TryIntrinsifyHelper() {
  compiler::Label exit;
  set_intrinsic_slow_path_label(&exit);

  if (FLAG_intrinsify) {
    // Intrinsification skips arguments checks, therefore disable if in checked
    // mode or strong mode.
    //
    // Though for implicit getters, which have only the receiver as parameter,
    // there are no checks necessary in any case and we can therefore intrinsify
    // them even in checked mode and strong mode.
    switch (parsed_function().function().kind()) {
      case RawFunction::kImplicitGetter: {
        Field& field = Field::Handle(function().accessor_field());
        ASSERT(!field.IsNull());
#if defined(DEBUG)
        // HACK: Clone the field to ignore assertion in Field::guarded_cid().
        // The assertion is intended to ensure that the background compiler sees
        // consistent cids, but that's not important in this case because
        // IsPotentialUnboxedField can go from true to false, but not false to
        // true, and we only do this optimisation if it is false.
        field = field.CloneFromOriginal();
#endif

        // Only intrinsify getter if the field cannot contain a mutable double.
        // Reading from a mutable double box requires allocating a fresh double.
        if (field.is_instance() &&
            (FLAG_precompiled_mode || !IsPotentialUnboxedField(field))) {
          SpecialStatsBegin(CombinedCodeStatistics::kTagIntrinsics);
          GenerateGetterIntrinsic(compiler::target::Field::OffsetOf(field));
          SpecialStatsEnd(CombinedCodeStatistics::kTagIntrinsics);
          return true;
        }
        return false;
      }
      case RawFunction::kImplicitSetter: {
        if (!isolate()->argument_type_checks()) {
          Field& field = Field::Handle(function().accessor_field());
          ASSERT(!field.IsNull());
#if defined(DEBUG)
          // HACK: Clone the field to ignore assertion in Field::guarded_cid().
          // The same reasons as above apply, but we only check if it's dynamic.
          field = field.CloneFromOriginal();
#endif

          if (field.is_instance() &&
              (FLAG_precompiled_mode || field.guarded_cid() == kDynamicCid)) {
            SpecialStatsBegin(CombinedCodeStatistics::kTagIntrinsics);
            GenerateSetterIntrinsic(compiler::target::Field::OffsetOf(field));
            SpecialStatsEnd(CombinedCodeStatistics::kTagIntrinsics);
            return true;
          }
          return false;
        }
        break;
      }
#if !defined(TARGET_ARCH_DBC) && !defined(TARGET_ARCH_IA32)
      case RawFunction::kMethodExtractor: {
        auto& extracted_method = Function::ZoneHandle(
            parsed_function().function().extracted_method_closure());
        auto& klass = Class::Handle(extracted_method.Owner());
        const intptr_t type_arguments_field_offset =
            compiler::target::Class::HasTypeArgumentsField(klass)
                ? (compiler::target::Class::TypeArgumentsFieldOffset(klass) -
                   kHeapObjectTag)
                : 0;

        SpecialStatsBegin(CombinedCodeStatistics::kTagIntrinsics);
        GenerateMethodExtractorIntrinsic(extracted_method,
                                         type_arguments_field_offset);
        SpecialStatsEnd(CombinedCodeStatistics::kTagIntrinsics);
        return true;
      }
#endif  // !defined(TARGET_ARCH_DBC) && !defined(TARGET_ARCH_IA32)
      default:
        break;
    }
  }

  EnterIntrinsicMode();

  SpecialStatsBegin(CombinedCodeStatistics::kTagIntrinsics);
  bool complete = compiler::Intrinsifier::Intrinsify(parsed_function(), this);
  SpecialStatsEnd(CombinedCodeStatistics::kTagIntrinsics);

  ExitIntrinsicMode();

  // "Deoptimization" from intrinsic continues here. All deoptimization
  // branches from intrinsic code redirect to here where the slow-path
  // (normal function body) starts.
  // This means that there must not be any side-effects in intrinsic code
  // before any deoptimization point.
  assembler()->Bind(intrinsic_slow_path_label());
  set_intrinsic_slow_path_label(nullptr);
  return complete;
}

// DBC is very different from other architectures in how it performs instance
// and static calls because it does not use stubs.
#if !defined(TARGET_ARCH_DBC)
void FlowGraphCompiler::GenerateCallWithDeopt(TokenPosition token_pos,
                                              intptr_t deopt_id,
                                              const Code& stub,
                                              RawPcDescriptors::Kind kind,
                                              LocationSummary* locs) {
  GenerateCall(token_pos, stub, kind, locs);
  const intptr_t deopt_id_after = DeoptId::ToDeoptAfter(deopt_id);
  if (is_optimizing()) {
    AddDeoptIndexAtCall(deopt_id_after);
  } else {
    // Add deoptimization continuation point after the call and before the
    // arguments are removed.
    AddCurrentDescriptor(RawPcDescriptors::kDeopt, deopt_id_after, token_pos);
  }
}

static const Code& StubEntryFor(const ICData& ic_data, bool optimized) {
  switch (ic_data.NumArgsTested()) {
    case 1:
#if defined(TARGET_ARCH_X64)
      if (ic_data.is_tracking_exactness()) {
        if (optimized) {
          return StubCode::OneArgOptimizedCheckInlineCacheWithExactnessCheck();
        } else {
          return StubCode::OneArgCheckInlineCacheWithExactnessCheck();
        }
      }
#else
      // TODO(dartbug.com/34170) Port exactness tracking to other platforms.
      ASSERT(!ic_data.is_tracking_exactness());
#endif
      return optimized ? StubCode::OneArgOptimizedCheckInlineCache()
                       : StubCode::OneArgCheckInlineCache();
    case 2:
      ASSERT(!ic_data.is_tracking_exactness());
      return optimized ? StubCode::TwoArgsOptimizedCheckInlineCache()
                       : StubCode::TwoArgsCheckInlineCache();
    default:
      ic_data.Print();
      UNIMPLEMENTED();
      return Code::Handle();
  }
}

void FlowGraphCompiler::GenerateInstanceCall(intptr_t deopt_id,
                                             TokenPosition token_pos,
                                             LocationSummary* locs,
                                             const ICData& ic_data_in,
                                             Code::EntryKind entry_kind) {
  ICData& ic_data = ICData::ZoneHandle(ic_data_in.Original());
  if (FLAG_precompiled_mode) {
    // TODO(#34162): Support unchecked entry-points in precompiled mode.
    ic_data = ic_data.AsUnaryClassChecks();
    EmitInstanceCallAOT(ic_data, deopt_id, token_pos, locs, entry_kind);
    return;
  }
  ASSERT(!ic_data.IsNull());
  if (is_optimizing() && (ic_data_in.NumberOfUsedChecks() == 0)) {
    // Emit IC call that will count and thus may need reoptimization at
    // function entry.
    ASSERT(may_reoptimize() || flow_graph().IsCompiledForOsr());
    EmitOptimizedInstanceCall(StubEntryFor(ic_data, /*optimized=*/true),
                              ic_data, deopt_id, token_pos, locs, entry_kind);
    return;
  }

  if (is_optimizing()) {
    String& name = String::Handle(ic_data_in.target_name());
    const Array& arguments_descriptor =
        Array::Handle(ic_data_in.arguments_descriptor());
    EmitMegamorphicInstanceCall(name, arguments_descriptor, deopt_id, token_pos,
                                locs, kInvalidTryIndex);
    return;
  }

  EmitInstanceCallJIT(StubEntryFor(ic_data, /*optimized=*/false), ic_data,
                      deopt_id, token_pos, locs, entry_kind);
}

void FlowGraphCompiler::GenerateStaticCall(intptr_t deopt_id,
                                           TokenPosition token_pos,
                                           const Function& function,
                                           ArgumentsInfo args_info,
                                           LocationSummary* locs,
                                           const ICData& ic_data_in,
                                           ICData::RebindRule rebind_rule,
                                           Code::EntryKind entry_kind) {
  const ICData& ic_data = ICData::ZoneHandle(ic_data_in.Original());
  const Array& arguments_descriptor = Array::ZoneHandle(
      zone(), ic_data.IsNull() ? args_info.ToArgumentsDescriptor()
                               : ic_data.arguments_descriptor());
  ASSERT(ArgumentsDescriptor(arguments_descriptor).TypeArgsLen() ==
         args_info.type_args_len);
  if (is_optimizing() && !ForcedOptimization()) {
    EmitOptimizedStaticCall(function, arguments_descriptor,
                            args_info.count_with_type_args, deopt_id, token_pos,
                            locs, entry_kind);
  } else {
    ICData& call_ic_data = ICData::ZoneHandle(zone(), ic_data.raw());
    if (call_ic_data.IsNull()) {
      const intptr_t kNumArgsChecked = 0;
      call_ic_data =
          GetOrAddStaticCallICData(deopt_id, function, arguments_descriptor,
                                   kNumArgsChecked, rebind_rule)
              ->raw();
    }
    AddCurrentDescriptor(RawPcDescriptors::kRewind, deopt_id, token_pos);
    EmitUnoptimizedStaticCall(args_info.count_with_type_args, deopt_id,
                              token_pos, locs, call_ic_data);
  }
}

void FlowGraphCompiler::GenerateNumberTypeCheck(
    Register class_id_reg,
    const AbstractType& type,
    compiler::Label* is_instance_lbl,
    compiler::Label* is_not_instance_lbl) {
  assembler()->Comment("NumberTypeCheck");
  GrowableArray<intptr_t> args;
  if (type.IsNumberType()) {
    args.Add(kDoubleCid);
    args.Add(kMintCid);
  } else if (type.IsIntType()) {
    args.Add(kMintCid);
  } else if (type.IsDoubleType()) {
    args.Add(kDoubleCid);
  }
  CheckClassIds(class_id_reg, args, is_instance_lbl, is_not_instance_lbl);
}

void FlowGraphCompiler::GenerateStringTypeCheck(
    Register class_id_reg,
    compiler::Label* is_instance_lbl,
    compiler::Label* is_not_instance_lbl) {
  assembler()->Comment("StringTypeCheck");
  GrowableArray<intptr_t> args;
  args.Add(kOneByteStringCid);
  args.Add(kTwoByteStringCid);
  args.Add(kExternalOneByteStringCid);
  args.Add(kExternalTwoByteStringCid);
  CheckClassIds(class_id_reg, args, is_instance_lbl, is_not_instance_lbl);
}

void FlowGraphCompiler::GenerateListTypeCheck(
    Register class_id_reg,
    compiler::Label* is_instance_lbl) {
  assembler()->Comment("ListTypeCheck");
  compiler::Label unknown;
  GrowableArray<intptr_t> args;
  args.Add(kArrayCid);
  args.Add(kGrowableObjectArrayCid);
  args.Add(kImmutableArrayCid);
  CheckClassIds(class_id_reg, args, is_instance_lbl, &unknown);
  assembler()->Bind(&unknown);
}
#endif  // !defined(TARGET_ARCH_DBC)

void FlowGraphCompiler::EmitComment(Instruction* instr) {
  if (!FLAG_support_il_printer || !FLAG_support_disassembler) {
    return;
  }
#ifndef PRODUCT
  char buffer[256];
  BufferFormatter f(buffer, sizeof(buffer));
  instr->PrintTo(&f);
  assembler()->Comment("%s", buffer);
#endif
}

#if !defined(TARGET_ARCH_DBC)
// TODO(vegorov) enable edge-counters on DBC if we consider them beneficial.
bool FlowGraphCompiler::NeedsEdgeCounter(BlockEntryInstr* block) {
  // Only emit an edge counter if there is not goto at the end of the block,
  // except for the entry block.
  return FLAG_reorder_basic_blocks &&
         (!block->last_instruction()->IsGoto() || block->IsFunctionEntry());
}

// Allocate a register that is not explictly blocked.
static Register AllocateFreeRegister(bool* blocked_registers) {
  for (intptr_t regno = 0; regno < kNumberOfCpuRegisters; regno++) {
    if (!blocked_registers[regno]) {
      blocked_registers[regno] = true;
      return static_cast<Register>(regno);
    }
  }
  UNREACHABLE();
  return kNoRegister;
}
#endif

void FlowGraphCompiler::AllocateRegistersLocally(Instruction* instr) {
  ASSERT(!is_optimizing());
  instr->InitializeLocationSummary(zone(), false);  // Not optimizing.

// No need to allocate registers based on LocationSummary on DBC as in
// unoptimized mode it's a stack based bytecode just like IR itself.
#if !defined(TARGET_ARCH_DBC)
  LocationSummary* locs = instr->locs();

  bool blocked_registers[kNumberOfCpuRegisters];

  // Connect input with peephole output for some special cases. All other
  // cases are handled by simply allocating registers and generating code.
  if (top_of_stack_ != nullptr) {
    const intptr_t p = locs->input_count() - 1;
    Location peephole = top_of_stack_->locs()->out(0);
    if (locs->in(p).IsUnallocated() || locs->in(p).IsConstant()) {
      // If input is unallocated, match with an output register, if set. Also,
      // if input is a direct constant, but the peephole output is a register,
      // use that register to avoid wasting the already generated code.
      if (peephole.IsRegister()) {
        locs->set_in(p, Location::RegisterLocation(peephole.reg()));
      }
    }
  }

  // Block all registers globally reserved by the assembler, etc and mark
  // the rest as free.
  for (intptr_t i = 0; i < kNumberOfCpuRegisters; i++) {
    blocked_registers[i] = (kDartAvailableCpuRegs & (1 << i)) == 0;
  }

  // Mark all fixed input, temp and output registers as used.
  for (intptr_t i = 0; i < locs->input_count(); i++) {
    Location loc = locs->in(i);
    if (loc.IsRegister()) {
      // Check that a register is not specified twice in the summary.
      ASSERT(!blocked_registers[loc.reg()]);
      blocked_registers[loc.reg()] = true;
    }
  }

  for (intptr_t i = 0; i < locs->temp_count(); i++) {
    Location loc = locs->temp(i);
    if (loc.IsRegister()) {
      // Check that a register is not specified twice in the summary.
      ASSERT(!blocked_registers[loc.reg()]);
      blocked_registers[loc.reg()] = true;
    }
  }

  if (locs->out(0).IsRegister()) {
    // Fixed output registers are allowed to overlap with
    // temps and inputs.
    blocked_registers[locs->out(0).reg()] = true;
  }

  // Allocate all unallocated input locations.
  const bool should_pop = !instr->IsPushArgument();
  for (intptr_t i = locs->input_count() - 1; i >= 0; i--) {
    Location loc = locs->in(i);
    Register reg = kNoRegister;
    if (loc.IsRegister()) {
      reg = loc.reg();
    } else if (loc.IsUnallocated()) {
      ASSERT((loc.policy() == Location::kRequiresRegister) ||
             (loc.policy() == Location::kWritableRegister) ||
             (loc.policy() == Location::kPrefersRegister) ||
             (loc.policy() == Location::kAny));
      reg = AllocateFreeRegister(blocked_registers);
      locs->set_in(i, Location::RegisterLocation(reg));
    }
    ASSERT(reg != kNoRegister || loc.IsConstant());

    // Inputs are consumed from the simulated frame (or a peephole push/pop).
    // In case of a call argument we leave it until the call instruction.
    if (should_pop) {
      if (top_of_stack_ != nullptr) {
        if (!loc.IsConstant()) {
          // Moves top of stack location of the peephole into the required
          // input. None of the required moves needs a temp register allocator.
          EmitMove(locs->in(i), top_of_stack_->locs()->out(0), nullptr);
        }
        top_of_stack_ = nullptr;  // consumed!
      } else if (loc.IsConstant()) {
        assembler()->Drop(1);
      } else {
        assembler()->PopRegister(reg);
      }
    }
  }

  // Allocate all unallocated temp locations.
  for (intptr_t i = 0; i < locs->temp_count(); i++) {
    Location loc = locs->temp(i);
    if (loc.IsUnallocated()) {
      ASSERT(loc.policy() == Location::kRequiresRegister);
      loc = Location::RegisterLocation(AllocateFreeRegister(blocked_registers));
      locs->set_temp(i, loc);
    }
  }

  Location result_location = locs->out(0);
  if (result_location.IsUnallocated()) {
    switch (result_location.policy()) {
      case Location::kAny:
      case Location::kPrefersRegister:
      case Location::kRequiresRegister:
      case Location::kWritableRegister:
        result_location =
            Location::RegisterLocation(AllocateFreeRegister(blocked_registers));
        break;
      case Location::kSameAsFirstInput:
        result_location = locs->in(0);
        break;
      case Location::kRequiresFpuRegister:
        UNREACHABLE();
        break;
    }
    locs->set_out(0, result_location);
  }
#endif  // !defined(TARGET_ARCH_DBC)
}

static uword RegMaskBit(Register reg) {
  return ((reg) != kNoRegister) ? (1 << (reg)) : 0;
}

ParallelMoveResolver::ParallelMoveResolver(FlowGraphCompiler* compiler)
    : compiler_(compiler), moves_(32) {}

void ParallelMoveResolver::EmitNativeCode(ParallelMoveInstr* parallel_move) {
  ASSERT(moves_.is_empty());
  // Build up a worklist of moves.
  BuildInitialMoveList(parallel_move);

  for (int i = 0; i < moves_.length(); ++i) {
    const MoveOperands& move = *moves_[i];
    // Skip constants to perform them last.  They don't block other moves
    // and skipping such moves with register destinations keeps those
    // registers free for the whole algorithm.
    if (!move.IsEliminated() && !move.src().IsConstant()) PerformMove(i);
  }

  // Perform the moves with constant sources.
  for (int i = 0; i < moves_.length(); ++i) {
    const MoveOperands& move = *moves_[i];
    if (!move.IsEliminated()) {
      ASSERT(move.src().IsConstant());
      compiler_->BeginCodeSourceRange();
      EmitMove(i);
      compiler_->EndCodeSourceRange(TokenPosition::kParallelMove);
    }
  }

  moves_.Clear();
}

void ParallelMoveResolver::BuildInitialMoveList(
    ParallelMoveInstr* parallel_move) {
  // Perform a linear sweep of the moves to add them to the initial list of
  // moves to perform, ignoring any move that is redundant (the source is
  // the same as the destination, the destination is ignored and
  // unallocated, or the move was already eliminated).
  for (int i = 0; i < parallel_move->NumMoves(); i++) {
    MoveOperands* move = parallel_move->MoveOperandsAt(i);
    if (!move->IsRedundant()) moves_.Add(move);
  }
}

void ParallelMoveResolver::PerformMove(int index) {
  // Each call to this function performs a move and deletes it from the move
  // graph.  We first recursively perform any move blocking this one.  We
  // mark a move as "pending" on entry to PerformMove in order to detect
  // cycles in the move graph.  We use operand swaps to resolve cycles,
  // which means that a call to PerformMove could change any source operand
  // in the move graph.

  ASSERT(!moves_[index]->IsPending());
  ASSERT(!moves_[index]->IsRedundant());

  // Clear this move's destination to indicate a pending move.  The actual
  // destination is saved in a stack-allocated local.  Recursion may allow
  // multiple moves to be pending.
  ASSERT(!moves_[index]->src().IsInvalid());
  Location destination = moves_[index]->MarkPending();

  // Perform a depth-first traversal of the move graph to resolve
  // dependencies.  Any unperformed, unpending move with a source the same
  // as this one's destination blocks this one so recursively perform all
  // such moves.
  for (int i = 0; i < moves_.length(); ++i) {
    const MoveOperands& other_move = *moves_[i];
    if (other_move.Blocks(destination) && !other_move.IsPending()) {
      // Though PerformMove can change any source operand in the move graph,
      // this call cannot create a blocking move via a swap (this loop does
      // not miss any).  Assume there is a non-blocking move with source A
      // and this move is blocked on source B and there is a swap of A and
      // B.  Then A and B must be involved in the same cycle (or they would
      // not be swapped).  Since this move's destination is B and there is
      // only a single incoming edge to an operand, this move must also be
      // involved in the same cycle.  In that case, the blocking move will
      // be created but will be "pending" when we return from PerformMove.
      PerformMove(i);
    }
  }

  // We are about to resolve this move and don't need it marked as
  // pending, so restore its destination.
  moves_[index]->ClearPending(destination);

  // This move's source may have changed due to swaps to resolve cycles and
  // so it may now be the last move in the cycle.  If so remove it.
  if (moves_[index]->src().Equals(destination)) {
    moves_[index]->Eliminate();
    return;
  }

  // The move may be blocked on a (at most one) pending move, in which case
  // we have a cycle.  Search for such a blocking move and perform a swap to
  // resolve it.
  for (int i = 0; i < moves_.length(); ++i) {
    const MoveOperands& other_move = *moves_[i];
    if (other_move.Blocks(destination)) {
      ASSERT(other_move.IsPending());
      compiler_->BeginCodeSourceRange();
      EmitSwap(index);
      compiler_->EndCodeSourceRange(TokenPosition::kParallelMove);
      return;
    }
  }

  // This move is not blocked.
  compiler_->BeginCodeSourceRange();
  EmitMove(index);
  compiler_->EndCodeSourceRange(TokenPosition::kParallelMove);
}

#if !defined(TARGET_ARCH_DBC)
void ParallelMoveResolver::EmitMove(int index) {
  MoveOperands* const move = moves_[index];
  const Location dst = move->dest();
  if (dst.IsStackSlot() || dst.IsDoubleStackSlot()) {
    ASSERT((dst.base_reg() != FPREG) ||
           ((-compiler::target::frame_layout.VariableIndexForFrameSlot(
                dst.stack_index())) < compiler_->StackSize()));
  }
  const Location src = move->src();
  ParallelMoveResolver::TemporaryAllocator temp(this, /*blocked=*/kNoRegister);
  compiler_->EmitMove(dst, src, &temp);
#if defined(DEBUG)
  // Allocating a scratch register here may cause stack spilling. Neither the
  // source nor destination register should be SP-relative in that case.
  for (const Location loc : {dst, src}) {
    ASSERT(!temp.DidAllocateTemporary() || !loc.HasStackIndex() ||
           loc.base_reg() != SPREG);
  }
#endif
  move->Eliminate();
}
#endif

bool ParallelMoveResolver::IsScratchLocation(Location loc) {
  for (int i = 0; i < moves_.length(); ++i) {
    if (moves_[i]->Blocks(loc)) {
      return false;
    }
  }

  for (int i = 0; i < moves_.length(); ++i) {
    if (moves_[i]->dest().Equals(loc)) {
      return true;
    }
  }

  return false;
}

intptr_t ParallelMoveResolver::AllocateScratchRegister(
    Location::Kind kind,
    uword blocked_mask,
    intptr_t first_free_register,
    intptr_t last_free_register,
    bool* spilled) {
  COMPILE_ASSERT(static_cast<intptr_t>(sizeof(blocked_mask)) * kBitsPerByte >=
                 kNumberOfFpuRegisters);
  COMPILE_ASSERT(static_cast<intptr_t>(sizeof(blocked_mask)) * kBitsPerByte >=
                 kNumberOfCpuRegisters);
  intptr_t scratch = -1;
  for (intptr_t reg = first_free_register; reg <= last_free_register; reg++) {
    if ((((1 << reg) & blocked_mask) == 0) &&
        IsScratchLocation(Location::MachineRegisterLocation(kind, reg))) {
      scratch = reg;
      break;
    }
  }

  if (scratch == -1) {
    *spilled = true;
    for (intptr_t reg = first_free_register; reg <= last_free_register; reg++) {
      if (((1 << reg) & blocked_mask) == 0) {
        scratch = reg;
        break;
      }
    }
  } else {
    *spilled = false;
  }

  return scratch;
}

ParallelMoveResolver::ScratchFpuRegisterScope::ScratchFpuRegisterScope(
    ParallelMoveResolver* resolver,
    FpuRegister blocked)
    : resolver_(resolver), reg_(kNoFpuRegister), spilled_(false) {
  COMPILE_ASSERT(FpuTMP != kNoFpuRegister);
  uword blocked_mask =
      ((blocked != kNoFpuRegister) ? 1 << blocked : 0) | 1 << FpuTMP;
  reg_ = static_cast<FpuRegister>(resolver_->AllocateScratchRegister(
      Location::kFpuRegister, blocked_mask, 0, kNumberOfFpuRegisters - 1,
      &spilled_));

  if (spilled_) {
    resolver->SpillFpuScratch(reg_);
  }
}

ParallelMoveResolver::ScratchFpuRegisterScope::~ScratchFpuRegisterScope() {
  if (spilled_) {
    resolver_->RestoreFpuScratch(reg_);
  }
}

ParallelMoveResolver::TemporaryAllocator::TemporaryAllocator(
    ParallelMoveResolver* resolver,
    Register blocked)
    : resolver_(resolver),
      blocked_(blocked),
      reg_(kNoRegister),
      spilled_(false) {}

Register ParallelMoveResolver::TemporaryAllocator::AllocateTemporary() {
  ASSERT(reg_ == kNoRegister);

  uword blocked_mask = RegMaskBit(blocked_) | kReservedCpuRegisters;
  if (resolver_->compiler_->intrinsic_mode()) {
    // Block additional registers that must be preserved for intrinsics.
    blocked_mask |= RegMaskBit(ARGS_DESC_REG);
#if !defined(TARGET_ARCH_IA32)
    // Need to preserve CODE_REG to be able to store the PC marker
    // and load the pool pointer.
    blocked_mask |= RegMaskBit(CODE_REG);
#endif
  }
  reg_ = static_cast<Register>(
      resolver_->AllocateScratchRegister(Location::kRegister, blocked_mask, 0,
                                         kNumberOfCpuRegisters - 1, &spilled_));

  if (spilled_) {
    resolver_->SpillScratch(reg_);
  }

  DEBUG_ONLY(allocated_ = true;)
  return reg_;
}

void ParallelMoveResolver::TemporaryAllocator::ReleaseTemporary() {
  if (spilled_) {
    resolver_->RestoreScratch(reg_);
  }
  reg_ = kNoRegister;
}

ParallelMoveResolver::ScratchRegisterScope::ScratchRegisterScope(
    ParallelMoveResolver* resolver,
    Register blocked)
    : allocator_(resolver, blocked) {
  reg_ = allocator_.AllocateTemporary();
}

ParallelMoveResolver::ScratchRegisterScope::~ScratchRegisterScope() {
  allocator_.ReleaseTemporary();
}

const ICData* FlowGraphCompiler::GetOrAddInstanceCallICData(
    intptr_t deopt_id,
    const String& target_name,
    const Array& arguments_descriptor,
    intptr_t num_args_tested,
    const AbstractType& receiver_type) {
  if ((deopt_id_to_ic_data_ != NULL) &&
      ((*deopt_id_to_ic_data_)[deopt_id] != NULL)) {
    const ICData* res = (*deopt_id_to_ic_data_)[deopt_id];
    ASSERT(res->deopt_id() == deopt_id);
    ASSERT(res->target_name() == target_name.raw());
    ASSERT(res->NumArgsTested() == num_args_tested);
    ASSERT(res->TypeArgsLen() ==
           ArgumentsDescriptor(arguments_descriptor).TypeArgsLen());
    ASSERT(!res->is_static_call());
    ASSERT(res->receivers_static_type() == receiver_type.raw());
    return res;
  }
  const ICData& ic_data = ICData::ZoneHandle(
      zone(), ICData::New(parsed_function().function(), target_name,
                          arguments_descriptor, deopt_id, num_args_tested,
                          ICData::kInstance, receiver_type));
  if (deopt_id_to_ic_data_ != NULL) {
    (*deopt_id_to_ic_data_)[deopt_id] = &ic_data;
  }
  ASSERT(!ic_data.is_static_call());
  return &ic_data;
}

const ICData* FlowGraphCompiler::GetOrAddStaticCallICData(
    intptr_t deopt_id,
    const Function& target,
    const Array& arguments_descriptor,
    intptr_t num_args_tested,
    ICData::RebindRule rebind_rule) {
  if ((deopt_id_to_ic_data_ != NULL) &&
      ((*deopt_id_to_ic_data_)[deopt_id] != NULL)) {
    const ICData* res = (*deopt_id_to_ic_data_)[deopt_id];
    ASSERT(res->deopt_id() == deopt_id);
    ASSERT(res->target_name() == target.name());
    ASSERT(res->NumArgsTested() == num_args_tested);
    ASSERT(res->TypeArgsLen() ==
           ArgumentsDescriptor(arguments_descriptor).TypeArgsLen());
    ASSERT(res->is_static_call());
    return res;
  }

  const ICData& ic_data = ICData::ZoneHandle(
      zone(),
      ICData::New(parsed_function().function(),
                  String::Handle(zone(), target.name()), arguments_descriptor,
                  deopt_id, num_args_tested, rebind_rule));
  ic_data.AddTarget(target);
  if (deopt_id_to_ic_data_ != NULL) {
    (*deopt_id_to_ic_data_)[deopt_id] = &ic_data;
  }
  return &ic_data;
}

intptr_t FlowGraphCompiler::GetOptimizationThreshold() const {
  intptr_t threshold;
  if (is_optimizing()) {
    threshold = FLAG_reoptimization_counter_threshold;
  } else if (parsed_function_.function().IsIrregexpFunction()) {
    threshold = FLAG_regexp_optimization_counter_threshold;
  } else if (FLAG_randomize_optimization_counter) {
    threshold = Thread::Current()->GetRandomUInt64() %
                FLAG_optimization_counter_threshold;
  } else {
    const intptr_t basic_blocks = flow_graph().preorder().length();
    ASSERT(basic_blocks > 0);
    threshold = FLAG_optimization_counter_scale * basic_blocks +
                FLAG_min_optimization_counter_threshold;
    if (threshold > FLAG_optimization_counter_threshold) {
      threshold = FLAG_optimization_counter_threshold;
    }
  }

  // Threshold = 0 doesn't make sense because we increment the counter before
  // testing against the threshold. Perhaps we could interpret it to mean
  // "generate optimized code immediately without unoptimized compilation
  // first", but this isn't supported in our pipeline because there would be no
  // code for the optimized code to deoptimize into.
  if (threshold == 0) threshold = 1;

  // See Compiler::CanOptimizeFunction. In short, we have to allow the
  // unoptimized code to run at least once to prevent an infinite compilation
  // loop.
  if (threshold == 1 && parsed_function().function().HasBreakpoint()) {
    threshold = 2;
  }

  return threshold;
}

const Class& FlowGraphCompiler::BoxClassFor(Representation rep) {
  switch (rep) {
    case kUnboxedFloat:
    case kUnboxedDouble:
      return double_class();
    case kUnboxedFloat32x4:
      return float32x4_class();
    case kUnboxedFloat64x2:
      return float64x2_class();
    case kUnboxedInt32x4:
      return int32x4_class();
    case kUnboxedInt64:
      return mint_class();
    default:
      UNREACHABLE();
      return Class::ZoneHandle();
  }
}

void FlowGraphCompiler::BeginCodeSourceRange() {
  code_source_map_builder_->BeginCodeSourceRange(assembler()->CodeSize());
}

void FlowGraphCompiler::EndCodeSourceRange(TokenPosition token_pos) {
  code_source_map_builder_->EndCodeSourceRange(assembler()->CodeSize(),
                                               token_pos);
}

const CallTargets* FlowGraphCompiler::ResolveCallTargetsForReceiverCid(
    intptr_t cid,
    const String& selector,
    const Array& args_desc_array) {
  Zone* zone = Thread::Current()->zone();

  ArgumentsDescriptor args_desc(args_desc_array);

  Function& fn = Function::ZoneHandle(zone);
  if (!LookupMethodFor(cid, selector, args_desc, &fn)) return NULL;

  CallTargets* targets = new (zone) CallTargets(zone);
  targets->Add(new (zone) TargetInfo(cid, cid, &fn, /* count = */ 1,
                                     StaticTypeExactnessState::NotTracking()));

  return targets;
}

bool FlowGraphCompiler::LookupMethodFor(int class_id,
                                        const String& name,
                                        const ArgumentsDescriptor& args_desc,
                                        Function* fn_return,
                                        bool* class_is_abstract_return) {
  Thread* thread = Thread::Current();
  Isolate* isolate = thread->isolate();
  Zone* zone = thread->zone();
  if (class_id < 0) return false;
  if (class_id >= isolate->class_table()->NumCids()) return false;

  RawClass* raw_class = isolate->class_table()->At(class_id);
  if (raw_class == NULL) return false;
  Class& cls = Class::Handle(zone, raw_class);
  if (cls.IsNull()) return false;
  if (!cls.is_finalized()) return false;
  if (Array::Handle(cls.functions()).IsNull()) return false;

  if (class_is_abstract_return != NULL) {
    *class_is_abstract_return = cls.is_abstract();
  }
  const bool allow_add = false;
  Function& target_function =
      Function::Handle(zone, Resolver::ResolveDynamicForReceiverClass(
                                 cls, name, args_desc, allow_add));
  if (target_function.IsNull()) return false;
  *fn_return = target_function.raw();
  return true;
}

#if !defined(TARGET_ARCH_DBC)
// DBC emits calls very differently from other architectures due to its
// interpreted nature.
void FlowGraphCompiler::EmitPolymorphicInstanceCall(
    const CallTargets& targets,
    const InstanceCallInstr& original_call,
    ArgumentsInfo args_info,
    intptr_t deopt_id,
    TokenPosition token_pos,
    LocationSummary* locs,
    bool complete,
    intptr_t total_ic_calls) {
  if (FLAG_polymorphic_with_deopt) {
    compiler::Label* deopt =
        AddDeoptStub(deopt_id, ICData::kDeoptPolymorphicInstanceCallTestFail);
    compiler::Label ok;
    EmitTestAndCall(targets, original_call.function_name(), args_info,
                    deopt,  // No cid match.
                    &ok,    // Found cid.
                    deopt_id, token_pos, locs, complete, total_ic_calls,
                    original_call.entry_kind());
    assembler()->Bind(&ok);
  } else {
    if (complete) {
      compiler::Label ok;
      EmitTestAndCall(targets, original_call.function_name(), args_info,
                      NULL,  // No cid match.
                      &ok,   // Found cid.
                      deopt_id, token_pos, locs, true, total_ic_calls,
                      original_call.entry_kind());
      assembler()->Bind(&ok);
    } else {
      const ICData& unary_checks = ICData::ZoneHandle(
          zone(), original_call.ic_data()->AsUnaryClassChecks());
      // TODO(sjindel/entrypoints): Support skiping type checks on switchable
      // calls.
      EmitInstanceCallAOT(unary_checks, deopt_id, token_pos, locs);
    }
  }
}

#define __ assembler()->
void FlowGraphCompiler::EmitTestAndCall(const CallTargets& targets,
                                        const String& function_name,
                                        ArgumentsInfo args_info,
                                        compiler::Label* failed,
                                        compiler::Label* match_found,
                                        intptr_t deopt_id,
                                        TokenPosition token_index,
                                        LocationSummary* locs,
                                        bool complete,
                                        intptr_t total_ic_calls,
                                        Code::EntryKind entry_kind) {
  ASSERT(is_optimizing());
  ASSERT(complete || (failed != nullptr));  // Complete calls can't fail.

  const Array& arguments_descriptor =
      Array::ZoneHandle(zone(), args_info.ToArgumentsDescriptor());
  EmitTestAndCallLoadReceiver(args_info.count_without_type_args,
                              arguments_descriptor);

  static const int kNoCase = -1;
  int smi_case = kNoCase;
  int which_case_to_skip = kNoCase;

  const int length = targets.length();
  ASSERT(length > 0);
  int non_smi_length = length;

  // Find out if one of the classes in one of the cases is the Smi class. We
  // will be handling that specially.
  for (int i = 0; i < length; i++) {
    const intptr_t start = targets[i].cid_start;
    if (start > kSmiCid) continue;
    const intptr_t end = targets[i].cid_end;
    if (end >= kSmiCid) {
      smi_case = i;
      if (start == kSmiCid && end == kSmiCid) {
        // If this case has only the Smi class then we won't need to emit it at
        // all later.
        which_case_to_skip = i;
        non_smi_length--;
      }
      break;
    }
  }

  if (smi_case != kNoCase) {
    compiler::Label after_smi_test;
    // If the call is complete and there are no other possible receiver
    // classes - then receiver can only be a smi value and we don't need
    // to check if it is a smi.
    if (!(complete && non_smi_length == 0)) {
      EmitTestAndCallSmiBranch(non_smi_length == 0 ? failed : &after_smi_test,
                               /* jump_if_smi= */ false);
    }

    // Do not use the code from the function, but let the code be patched so
    // that we can record the outgoing edges to other code.
    const Function& function = *targets.TargetAt(smi_case)->target;
    GenerateStaticDartCall(deopt_id, token_index, RawPcDescriptors::kOther,
                           locs, function, entry_kind);
    __ Drop(args_info.count_with_type_args);
    if (match_found != NULL) {
      __ Jump(match_found);
    }
    __ Bind(&after_smi_test);
  } else {
    if (!complete) {
      // Smi is not a valid class.
      EmitTestAndCallSmiBranch(failed, /* jump_if_smi = */ true);
    }
  }

  if (non_smi_length == 0) {
    // If non_smi_length is 0 then only a Smi check was needed; the Smi check
    // above will fail if there was only one check and receiver is not Smi.
    return;
  }

  bool add_megamorphic_call = false;
  int bias = 0;

  // Value is not Smi.
  EmitTestAndCallLoadCid(EmitTestCidRegister());

  int last_check = which_case_to_skip == length - 1 ? length - 2 : length - 1;

  for (intptr_t i = 0; i < length; i++) {
    if (i == which_case_to_skip) continue;
    const bool is_last_check = (i == last_check);
    const int count = targets.TargetAt(i)->count;
    if (!is_last_check && !complete && count < (total_ic_calls >> 5)) {
      // This case is hit too rarely to be worth writing class-id checks inline
      // for.  Note that we can't do this for calls with only one target because
      // the type propagator may have made use of that and expects a deopt if
      // a new class is seen at this calls site.  See IsMonomorphic.
      add_megamorphic_call = true;
      break;
    }
    compiler::Label next_test;
    if (!complete || !is_last_check) {
      bias = EmitTestAndCallCheckCid(assembler(),
                                     is_last_check ? failed : &next_test,
                                     EmitTestCidRegister(), targets[i], bias,
                                     /*jump_on_miss =*/true);
    }
    // Do not use the code from the function, but let the code be patched so
    // that we can record the outgoing edges to other code.
    const Function& function = *targets.TargetAt(i)->target;
    GenerateStaticDartCall(deopt_id, token_index, RawPcDescriptors::kOther,
                           locs, function, entry_kind);
    __ Drop(args_info.count_with_type_args);
    if (!is_last_check || add_megamorphic_call) {
      __ Jump(match_found);
    }
    __ Bind(&next_test);
  }
  if (add_megamorphic_call) {
    int try_index = kInvalidTryIndex;
    EmitMegamorphicInstanceCall(function_name, arguments_descriptor, deopt_id,
                                token_index, locs, try_index);
  }
}

bool FlowGraphCompiler::GenerateSubtypeRangeCheck(Register class_id_reg,
                                                  const Class& type_class,
                                                  compiler::Label* is_subtype) {
  HierarchyInfo* hi = Thread::Current()->hierarchy_info();
  if (hi != NULL) {
    const CidRangeVector& ranges =
        hi->SubtypeRangesForClass(type_class,
                                  /*include_abstract=*/false,
                                  /*exclude_null=*/false);
    if (ranges.length() <= kMaxNumberOfCidRangesToTest) {
      GenerateCidRangesCheck(assembler(), class_id_reg, ranges, is_subtype);
      return true;
    }
  }

  // We don't have cid-ranges for subclasses, so we'll just test against the
  // class directly if it's non-abstract.
  if (!type_class.is_abstract()) {
    __ CompareImmediate(class_id_reg, type_class.id());
    __ BranchIf(EQUAL, is_subtype);
  }
  return false;
}

void FlowGraphCompiler::GenerateCidRangesCheck(
    compiler::Assembler* assembler,
    Register class_id_reg,
    const CidRangeVector& cid_ranges,
    compiler::Label* inside_range_lbl,
    compiler::Label* outside_range_lbl,
    bool fall_through_if_inside) {
  // If there are no valid class ranges, the check will fail.  If we are
  // supposed to fall-through in the positive case, we'll explicitly jump to
  // the [outside_range_lbl].
  if (cid_ranges.length() == 1 && cid_ranges[0].IsIllegalRange()) {
    if (fall_through_if_inside) {
      assembler->Jump(outside_range_lbl);
    }
    return;
  }

  int bias = 0;
  for (intptr_t i = 0; i < cid_ranges.length(); ++i) {
    const CidRange& range = cid_ranges[i];
    RELEASE_ASSERT(!range.IsIllegalRange());
    const bool last_round = i == (cid_ranges.length() - 1);

    compiler::Label* jump_label = last_round && fall_through_if_inside
                                      ? outside_range_lbl
                                      : inside_range_lbl;
    const bool jump_on_miss = last_round && fall_through_if_inside;

    bias = EmitTestAndCallCheckCid(assembler, jump_label, class_id_reg, range,
                                   bias, jump_on_miss);
  }
}

bool FlowGraphCompiler::ShouldUseTypeTestingStubFor(bool optimizing,
                                                    const AbstractType& type) {
  return FLAG_precompiled_mode ||
         (optimizing &&
          (type.IsTypeParameter() || (type.IsType() && type.IsInstantiated())));
}

void FlowGraphCompiler::GenerateAssertAssignableViaTypeTestingStub(
    const AbstractType& dst_type,
    const String& dst_name,
    const Register instance_reg,
    const Register instantiator_type_args_reg,
    const Register function_type_args_reg,
    const Register subtype_cache_reg,
    const Register dst_type_reg,
    const Register scratch_reg,
    compiler::Label* done) {
  TypeUsageInfo* type_usage_info = thread()->type_usage_info();

  // If the int type is assignable to [dst_type] we special case it on the
  // caller side!
  const Type& int_type = Type::Handle(zone(), Type::IntType());
  bool is_non_smi = false;
  if (int_type.IsSubtypeOf(dst_type, Heap::kOld)) {
    __ BranchIfSmi(instance_reg, done);
    is_non_smi = true;
  }

  // We can handle certain types very efficiently on the call site (with a
  // bailout to the normal stub, which will do a runtime call).
  if (dst_type.IsTypeParameter()) {
    const TypeParameter& type_param = TypeParameter::Cast(dst_type);
    const Register kTypeArgumentsReg = type_param.IsClassTypeParameter()
                                           ? instantiator_type_args_reg
                                           : function_type_args_reg;

    // Check if type arguments are null, i.e. equivalent to vector of dynamic.
    __ CompareObject(kTypeArgumentsReg, Object::null_object());
    __ BranchIf(EQUAL, done);
    __ LoadField(
        dst_type_reg,
        compiler::FieldAddress(kTypeArgumentsReg,
                               compiler::target::TypeArguments::type_at_offset(
                                   type_param.index())));
    if (type_usage_info != NULL) {
      type_usage_info->UseTypeInAssertAssignable(dst_type);
    }
  } else {
    HierarchyInfo* hi = Thread::Current()->hierarchy_info();
    if (hi != NULL) {
      const Class& type_class = Class::Handle(zone(), dst_type.type_class());

      bool check_handled_at_callsite = false;
      bool used_cid_range_check = false;
      const bool can_use_simple_cid_range_test =
          hi->CanUseSubtypeRangeCheckFor(dst_type);
      if (can_use_simple_cid_range_test) {
        const CidRangeVector& ranges =
            hi->SubtypeRangesForClass(type_class,
                                      /*include_abstract=*/false,
                                      /*exclude_null=*/false);
        if (ranges.length() <= kMaxNumberOfCidRangesToTest) {
          if (is_non_smi) {
            __ LoadClassId(scratch_reg, instance_reg);
          } else {
            __ LoadClassIdMayBeSmi(scratch_reg, instance_reg);
          }
          GenerateCidRangesCheck(assembler(), scratch_reg, ranges, done);
          used_cid_range_check = true;
          check_handled_at_callsite = true;
        }
      }

      if (!used_cid_range_check && can_use_simple_cid_range_test &&
          IsListClass(type_class)) {
        __ LoadClassIdMayBeSmi(scratch_reg, instance_reg);
        GenerateListTypeCheck(scratch_reg, done);
        used_cid_range_check = true;
      }

      // If we haven't handled the positive case of the type check on the
      // call-site, we want an optimized type testing stub and therefore record
      // it in the [TypeUsageInfo].
      if (!check_handled_at_callsite) {
        if (type_usage_info != NULL) {
          type_usage_info->UseTypeInAssertAssignable(dst_type);
        } else {
          ASSERT(!FLAG_precompiled_mode);
        }
      }
    }
    __ LoadObject(dst_type_reg, dst_type);
  }
}

#undef __
#endif

#if defined(DEBUG) && !defined(TARGET_ARCH_DBC)
// TODO(vegorov) re-enable frame state tracking on DBC. It is
// currently disabled because it relies on LocationSummaries and
// we don't use them during unoptimized compilation on DBC.
void FlowGraphCompiler::FrameStateUpdateWith(Instruction* instr) {
  ASSERT(!is_optimizing());

  switch (instr->tag()) {
    case Instruction::kPushArgument:
      // Do nothing.
      break;

    case Instruction::kDropTemps:
      FrameStatePop(instr->locs()->input_count() +
                    instr->AsDropTemps()->num_temps());
      break;

    default:
      FrameStatePop(instr->locs()->input_count());
      break;
  }

  ASSERT(!instr->locs()->can_call() || FrameStateIsSafeToCall());

  FrameStatePop(instr->ArgumentCount());
  Definition* defn = instr->AsDefinition();
  if ((defn != NULL) && defn->HasTemp()) {
    FrameStatePush(defn);
  }
}

void FlowGraphCompiler::FrameStatePush(Definition* defn) {
  Representation rep = defn->representation();
  if ((rep == kUnboxedDouble) || (rep == kUnboxedFloat64x2) ||
      (rep == kUnboxedFloat32x4)) {
    // LoadField instruction lies about its representation in the unoptimized
    // code because Definition::representation() can't depend on the type of
    // compilation but MakeLocationSummary and EmitNativeCode can.
    ASSERT(defn->IsLoadField() && defn->AsLoadField()->IsUnboxedLoad());
    ASSERT(defn->locs()->out(0).IsRegister());
    rep = kTagged;
  }
  ASSERT(!is_optimizing());
  ASSERT((rep == kTagged) || (rep == kUntagged));
  ASSERT(rep != kUntagged || flow_graph_.IsIrregexpFunction());
  frame_state_.Add(rep);
}

void FlowGraphCompiler::FrameStatePop(intptr_t count) {
  ASSERT(!is_optimizing());
  frame_state_.TruncateTo(
      Utils::Maximum(static_cast<intptr_t>(0), frame_state_.length() - count));
}

bool FlowGraphCompiler::FrameStateIsSafeToCall() {
  ASSERT(!is_optimizing());
  for (intptr_t i = 0; i < frame_state_.length(); i++) {
    if (frame_state_[i] != kTagged) {
      return false;
    }
  }
  return true;
}

void FlowGraphCompiler::FrameStateClear() {
  ASSERT(!is_optimizing());
  frame_state_.TruncateTo(0);
}
#endif  // defined(DEBUG) && !defined(TARGET_ARCH_DBC)

#if !defined(TARGET_ARCH_DBC)
#define __ compiler->assembler()->

void ThrowErrorSlowPathCode::EmitNativeCode(FlowGraphCompiler* compiler) {
  if (compiler::Assembler::EmittingComments()) {
    __ Comment("slow path %s operation", name());
  }
  const bool use_shared_stub =
      instruction()->UseSharedSlowPathStub(compiler->is_optimizing());
  const bool live_fpu_registers =
      instruction()->locs()->live_registers()->FpuRegisterCount() > 0;
  ASSERT(!use_shared_stub || num_args_ == 0);
  __ Bind(entry_label());
  EmitCodeAtSlowPathEntry(compiler);
  LocationSummary* locs = instruction()->locs();
  // Save registers as they are needed for lazy deopt / exception handling.
  if (!use_shared_stub) {
    compiler->SaveLiveRegisters(locs);
  }
  for (intptr_t i = 0; i < num_args_; ++i) {
    __ PushRegister(locs->in(i).reg());
  }
  if (use_shared_stub) {
    EmitSharedStubCall(compiler, live_fpu_registers);
  } else {
    __ CallRuntime(runtime_entry_, num_args_);
  }
  // Can't query deopt_id() without checking if instruction can deoptimize...
  intptr_t deopt_id = DeoptId::kNone;
  if (instruction()->CanDeoptimize() ||
      instruction()->CanBecomeDeoptimizationTarget()) {
    deopt_id = instruction()->deopt_id();
  }
  compiler->AddDescriptor(RawPcDescriptors::kOther,
                          compiler->assembler()->CodeSize(), deopt_id,
                          instruction()->token_pos(), try_index_);
  AddMetadataForRuntimeCall(compiler);
  compiler->RecordSafepoint(locs, num_args_);
  if ((try_index_ != kInvalidTryIndex) ||
      (compiler->CurrentTryIndex() != kInvalidTryIndex)) {
    Environment* env =
        compiler->SlowPathEnvironmentFor(instruction(), num_args_);
    if (FLAG_precompiled_mode) {
      compiler->RecordCatchEntryMoves(env, try_index_);
    } else if (env != nullptr) {
      compiler->AddSlowPathDeoptInfo(deopt_id, env);
    }
  }
  if (!use_shared_stub) {
    __ Breakpoint();
  }
}

#undef __
#endif  //  !defined(TARGET_ARCH_DBC)

#endif  // !defined(DART_PRECOMPILED_RUNTIME)

}  // namespace dart