compiler/optimizing/code_generator.cc - fp2-dev/platform/art - Gitiles

 /*
  * Copyright (C) 2014 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 #include "code_generator.h"

 #include "code_generator_arm.h"
 #include "code_generator_x86.h"
 #include "code_generator_x86_64.h"
 #include "compiled_method.h"
 #include "dex/verified_method.h"
 #include "driver/dex_compilation_unit.h"
 #include "gc_map_builder.h"
 #include "leb128.h"
 #include "mapping_table.h"
 #include "ssa_liveness_analysis.h"
 #include "utils/assembler.h"
 #include "verifier/dex_gc_map.h"
 #include "vmap_table.h"

 namespace art {

 void CodeGenerator::CompileBaseline(CodeAllocator* allocator, bool is_leaf) {
   const GrowableArray<HBasicBlock*>& blocks = GetGraph()->GetBlocks();
   DCHECK(blocks.Get(0) == GetGraph()->GetEntryBlock());
   DCHECK(GoesToNextBlock(GetGraph()->GetEntryBlock(), blocks.Get(1)));
   block_labels_.SetSize(blocks.Size());

   DCHECK_EQ(frame_size_, kUninitializedFrameSize);
   if (!is_leaf) {
     MarkNotLeaf();
   }
   ComputeFrameSize(GetGraph()->GetNumberOfLocalVRegs()
                      + GetGraph()->GetNumberOfTemporaries()
                      + 1 /* filler */,
                    0, /* the baseline compiler does not have live registers at slow path */
                    GetGraph()->GetMaximumNumberOfOutVRegs()
                      + 1 /* current method */);
   GenerateFrameEntry();

   HGraphVisitor* location_builder = GetLocationBuilder();
   HGraphVisitor* instruction_visitor = GetInstructionVisitor();
   for (size_t i = 0, e = blocks.Size(); i < e; ++i) {
     HBasicBlock* block = blocks.Get(i);
     Bind(GetLabelOf(block));
     for (HInstructionIterator it(block->GetInstructions()); !it.Done(); it.Advance()) {
       HInstruction* current = it.Current();
       current->Accept(location_builder);
       InitLocations(current);
       current->Accept(instruction_visitor);
     }
   }
   GenerateSlowPaths();

   size_t code_size = GetAssembler()->CodeSize();
   uint8_t* buffer = allocator->Allocate(code_size);
   MemoryRegion code(buffer, code_size);
   GetAssembler()->FinalizeInstructions(code);
 }

 void CodeGenerator::CompileOptimized(CodeAllocator* allocator) {
   // The frame size has already been computed during register allocation.
   DCHECK_NE(frame_size_, kUninitializedFrameSize);
   const GrowableArray<HBasicBlock*>& blocks = GetGraph()->GetBlocks();
   DCHECK(blocks.Get(0) == GetGraph()->GetEntryBlock());
   DCHECK(GoesToNextBlock(GetGraph()->GetEntryBlock(), blocks.Get(1)));
   block_labels_.SetSize(blocks.Size());

   GenerateFrameEntry();
   HGraphVisitor* instruction_visitor = GetInstructionVisitor();
   for (size_t i = 0, e = blocks.Size(); i < e; ++i) {
     HBasicBlock* block = blocks.Get(i);
     Bind(GetLabelOf(block));
     for (HInstructionIterator it(block->GetInstructions()); !it.Done(); it.Advance()) {
       HInstruction* current = it.Current();
       current->Accept(instruction_visitor);
     }
   }
   GenerateSlowPaths();

   size_t code_size = GetAssembler()->CodeSize();
   uint8_t* buffer = allocator->Allocate(code_size);
   MemoryRegion code(buffer, code_size);
   GetAssembler()->FinalizeInstructions(code);
 }

 void CodeGenerator::GenerateSlowPaths() {
   for (size_t i = 0, e = slow_paths_.Size(); i < e; ++i) {
     slow_paths_.Get(i)->EmitNativeCode(this);
   }
 }

 size_t CodeGenerator::AllocateFreeRegisterInternal(
     bool* blocked_registers, size_t number_of_registers) const {
   for (size_t regno = 0; regno < number_of_registers; regno++) {
     if (!blocked_registers[regno]) {
       blocked_registers[regno] = true;
       return regno;
     }
   }
   return -1;
 }

 void CodeGenerator::ComputeFrameSize(size_t number_of_spill_slots,
                                      size_t maximum_number_of_live_registers,
                                      size_t number_of_out_slots) {
   first_register_slot_in_slow_path_ = (number_of_out_slots + number_of_spill_slots) * kVRegSize;

   SetFrameSize(RoundUp(
       number_of_spill_slots * kVRegSize
       + number_of_out_slots * kVRegSize
       + maximum_number_of_live_registers * GetWordSize()
       + FrameEntrySpillSize(),
       kStackAlignment));
 }

 Location CodeGenerator::GetTemporaryLocation(HTemporary* temp) const {
   uint16_t number_of_locals = GetGraph()->GetNumberOfLocalVRegs();
   // Use the temporary region (right below the dex registers).
   int32_t slot = GetFrameSize() - FrameEntrySpillSize()
                                 - kVRegSize  // filler
                                 - (number_of_locals * kVRegSize)
                                 - ((1 + temp->GetIndex()) * kVRegSize);
   return Location::StackSlot(slot);
 }

 int32_t CodeGenerator::GetStackSlot(HLocal* local) const {
   uint16_t reg_number = local->GetRegNumber();
   uint16_t number_of_locals = GetGraph()->GetNumberOfLocalVRegs();
   if (reg_number >= number_of_locals) {
     // Local is a parameter of the method. It is stored in the caller's frame.
     return GetFrameSize() + kVRegSize  // ART method
                           + (reg_number - number_of_locals) * kVRegSize;
   } else {
     // Local is a temporary in this method. It is stored in this method's frame.
     return GetFrameSize() - FrameEntrySpillSize()
                           - kVRegSize  // filler.
                           - (number_of_locals * kVRegSize)
                           + (reg_number * kVRegSize);
   }
 }

 void CodeGenerator::AllocateRegistersLocally(HInstruction* instruction) const {
   LocationSummary* locations = instruction->GetLocations();
   if (locations == nullptr) return;

   for (size_t i = 0, e = GetNumberOfRegisters(); i < e; ++i) {
     blocked_registers_[i] = false;
   }

   // Mark all fixed input, temp and output registers as used.
   for (size_t i = 0, e = locations->GetInputCount(); i < e; ++i) {
     Location loc = locations->InAt(i);
     if (loc.IsRegister()) {
       // Check that a register is not specified twice in the summary.
       DCHECK(!blocked_registers_[loc.GetEncoding()]);
       blocked_registers_[loc.GetEncoding()] = true;
     }
   }

   for (size_t i = 0, e = locations->GetTempCount(); i < e; ++i) {
     Location loc = locations->GetTemp(i);
     if (loc.IsRegister()) {
       // Check that a register is not specified twice in the summary.
       DCHECK(!blocked_registers_[loc.GetEncoding()]);
       blocked_registers_[loc.GetEncoding()] = true;
     }
   }

   SetupBlockedRegisters(blocked_registers_);

   // Allocate all unallocated input locations.
   for (size_t i = 0, e = locations->GetInputCount(); i < e; ++i) {
     Location loc = locations->InAt(i);
     HInstruction* input = instruction->InputAt(i);
     if (loc.IsUnallocated()) {
       if (loc.GetPolicy() == Location::kRequiresRegister) {
         loc = Location::RegisterLocation(
             AllocateFreeRegister(input->GetType(), blocked_registers_));
       } else {
         DCHECK_EQ(loc.GetPolicy(), Location::kAny);
         HLoadLocal* load = input->AsLoadLocal();
         if (load != nullptr) {
           loc = GetStackLocation(load);
         } else {
           loc = Location::RegisterLocation(
               AllocateFreeRegister(input->GetType(), blocked_registers_));
         }
       }
       locations->SetInAt(i, loc);
     }
   }

   // Allocate all unallocated temp locations.
   for (size_t i = 0, e = locations->GetTempCount(); i < e; ++i) {
     Location loc = locations->GetTemp(i);
     if (loc.IsUnallocated()) {
       DCHECK_EQ(loc.GetPolicy(), Location::kRequiresRegister);
       // TODO: Adjust handling of temps. We currently consider temps to use
       // core registers. They may also use floating point registers at some point.
       loc = Location::RegisterLocation(static_cast<ManagedRegister>(
           AllocateFreeRegister(Primitive::kPrimInt, blocked_registers_)));
       locations->SetTempAt(i, loc);
     }
   }
   Location result_location = locations->Out();
   if (result_location.IsUnallocated()) {
     switch (result_location.GetPolicy()) {
       case Location::kAny:
       case Location::kRequiresRegister:
         result_location = Location::RegisterLocation(
             AllocateFreeRegister(instruction->GetType(), blocked_registers_));
         break;
       case Location::kSameAsFirstInput:
         result_location = locations->InAt(0);
         break;
     }
     locations->SetOut(result_location);
   }
 }

 void CodeGenerator::InitLocations(HInstruction* instruction) {
   if (instruction->GetLocations() == nullptr) {
     if (instruction->IsTemporary()) {
       HInstruction* previous = instruction->GetPrevious();
       Location temp_location = GetTemporaryLocation(instruction->AsTemporary());
       Move(previous, temp_location, instruction);
       previous->GetLocations()->SetOut(temp_location);
     }
     return;
   }
   AllocateRegistersLocally(instruction);
   for (size_t i = 0, e = instruction->InputCount(); i < e; ++i) {
     Location location = instruction->GetLocations()->InAt(i);
     if (location.IsValid()) {
       // Move the input to the desired location.
       Move(instruction->InputAt(i), location, instruction);
     }
   }
 }

 bool CodeGenerator::GoesToNextBlock(HBasicBlock* current, HBasicBlock* next) const {
   // We currently iterate over the block in insertion order.
   return current->GetBlockId() + 1 == next->GetBlockId();
 }

 Label* CodeGenerator::GetLabelOf(HBasicBlock* block) const {
   return block_labels_.GetRawStorage() + block->GetBlockId();
 }

 CodeGenerator* CodeGenerator::Create(ArenaAllocator* allocator,
                                      HGraph* graph,
                                      InstructionSet instruction_set) {
   switch (instruction_set) {
     case kArm:
     case kThumb2: {
       return new (allocator) arm::CodeGeneratorARM(graph);
     }
     case kMips:
       return nullptr;
     case kX86: {
       return new (allocator) x86::CodeGeneratorX86(graph);
     }
     case kX86_64: {
       return new (allocator) x86_64::CodeGeneratorX86_64(graph);
     }
     default:
       return nullptr;
   }
 }

 void CodeGenerator::BuildNativeGCMap(
     std::vector<uint8_t>* data, const DexCompilationUnit& dex_compilation_unit) const {
   const std::vector<uint8_t>& gc_map_raw =
       dex_compilation_unit.GetVerifiedMethod()->GetDexGcMap();
   verifier::DexPcToReferenceMap dex_gc_map(&(gc_map_raw)[0]);

   uint32_t max_native_offset = 0;
   for (size_t i = 0; i < pc_infos_.Size(); i++) {
     uint32_t native_offset = pc_infos_.Get(i).native_pc;
     if (native_offset > max_native_offset) {
       max_native_offset = native_offset;
     }
   }

   GcMapBuilder builder(data, pc_infos_.Size(), max_native_offset, dex_gc_map.RegWidth());
   for (size_t i = 0; i < pc_infos_.Size(); i++) {
     struct PcInfo pc_info = pc_infos_.Get(i);
     uint32_t native_offset = pc_info.native_pc;
     uint32_t dex_pc = pc_info.dex_pc;
     const uint8_t* references = dex_gc_map.FindBitMap(dex_pc, false);
     CHECK(references != NULL) << "Missing ref for dex pc 0x" << std::hex << dex_pc;
     builder.AddEntry(native_offset, references);
   }
 }

 void CodeGenerator::BuildMappingTable(std::vector<uint8_t>* data, SrcMap* src_map) const {
   uint32_t pc2dex_data_size = 0u;
   uint32_t pc2dex_entries = pc_infos_.Size();
   uint32_t pc2dex_offset = 0u;
   int32_t pc2dex_dalvik_offset = 0;
   uint32_t dex2pc_data_size = 0u;
   uint32_t dex2pc_entries = 0u;

   if (src_map != nullptr) {
     src_map->reserve(pc2dex_entries);
   }

   // We currently only have pc2dex entries.
   for (size_t i = 0; i < pc2dex_entries; i++) {
     struct PcInfo pc_info = pc_infos_.Get(i);
     pc2dex_data_size += UnsignedLeb128Size(pc_info.native_pc - pc2dex_offset);
     pc2dex_data_size += SignedLeb128Size(pc_info.dex_pc - pc2dex_dalvik_offset);
     pc2dex_offset = pc_info.native_pc;
     pc2dex_dalvik_offset = pc_info.dex_pc;
     if (src_map != nullptr) {
       src_map->push_back(SrcMapElem({pc2dex_offset, pc2dex_dalvik_offset}));
     }
   }

   uint32_t total_entries = pc2dex_entries + dex2pc_entries;
   uint32_t hdr_data_size = UnsignedLeb128Size(total_entries) + UnsignedLeb128Size(pc2dex_entries);
   uint32_t data_size = hdr_data_size + pc2dex_data_size + dex2pc_data_size;
   data->resize(data_size);

   uint8_t* data_ptr = &(*data)[0];
   uint8_t* write_pos = data_ptr;
   write_pos = EncodeUnsignedLeb128(write_pos, total_entries);
   write_pos = EncodeUnsignedLeb128(write_pos, pc2dex_entries);
   DCHECK_EQ(static_cast<size_t>(write_pos - data_ptr), hdr_data_size);
   uint8_t* write_pos2 = write_pos + pc2dex_data_size;

   pc2dex_offset = 0u;
   pc2dex_dalvik_offset = 0u;
   for (size_t i = 0; i < pc2dex_entries; i++) {
     struct PcInfo pc_info = pc_infos_.Get(i);
     DCHECK(pc2dex_offset <= pc_info.native_pc);
     write_pos = EncodeUnsignedLeb128(write_pos, pc_info.native_pc - pc2dex_offset);
     write_pos = EncodeSignedLeb128(write_pos, pc_info.dex_pc - pc2dex_dalvik_offset);
     pc2dex_offset = pc_info.native_pc;
     pc2dex_dalvik_offset = pc_info.dex_pc;
   }
   DCHECK_EQ(static_cast<size_t>(write_pos - data_ptr), hdr_data_size + pc2dex_data_size);
   DCHECK_EQ(static_cast<size_t>(write_pos2 - data_ptr), data_size);

   if (kIsDebugBuild) {
     // Verify the encoded table holds the expected data.
     MappingTable table(data_ptr);
     CHECK_EQ(table.TotalSize(), total_entries);
     CHECK_EQ(table.PcToDexSize(), pc2dex_entries);
     auto it = table.PcToDexBegin();
     auto it2 = table.DexToPcBegin();
     for (size_t i = 0; i < pc2dex_entries; i++) {
       struct PcInfo pc_info = pc_infos_.Get(i);
       CHECK_EQ(pc_info.native_pc, it.NativePcOffset());
       CHECK_EQ(pc_info.dex_pc, it.DexPc());
       ++it;
     }
     CHECK(it == table.PcToDexEnd());
     CHECK(it2 == table.DexToPcEnd());
   }
 }

 void CodeGenerator::BuildVMapTable(std::vector<uint8_t>* data) const {
   Leb128EncodingVector vmap_encoder;
   // We currently don't use callee-saved registers.
   size_t size = 0 + 1 /* marker */ + 0;
   vmap_encoder.Reserve(size + 1u);  // All values are likely to be one byte in ULEB128 (<128).
   vmap_encoder.PushBackUnsigned(size);
   vmap_encoder.PushBackUnsigned(VmapTable::kAdjustedFpMarker);

   *data = vmap_encoder.GetData();
 }

 void CodeGenerator::BuildStackMaps(std::vector<uint8_t>* data) {
   uint32_t size = stack_map_stream_.ComputeNeededSize();
   data->resize(size);
   MemoryRegion region(data->data(), size);
   stack_map_stream_.FillIn(region);
 }

 void CodeGenerator::RecordPcInfo(HInstruction* instruction, uint32_t dex_pc) {
   // Collect PC infos for the mapping table.
   struct PcInfo pc_info;
   pc_info.dex_pc = dex_pc;
   pc_info.native_pc = GetAssembler()->CodeSize();
   pc_infos_.Add(pc_info);

   // Populate stack map information.

   if (instruction == nullptr) {
     // For stack overflow checks.
     stack_map_stream_.AddStackMapEntry(dex_pc, pc_info.native_pc, 0, 0, 0, 0);
     return;
   }

   LocationSummary* locations = instruction->GetLocations();
   HEnvironment* environment = instruction->GetEnvironment();

   size_t environment_size = instruction->EnvironmentSize();

   size_t register_mask = 0;
   size_t inlining_depth = 0;
   stack_map_stream_.AddStackMapEntry(
       dex_pc, pc_info.native_pc, register_mask,
       locations->GetStackMask(), environment_size, inlining_depth);

   // Walk over the environment, and record the location of dex registers.
   for (size_t i = 0; i < environment_size; ++i) {
     HInstruction* current = environment->GetInstructionAt(i);
     if (current == nullptr) {
       stack_map_stream_.AddDexRegisterEntry(DexRegisterMap::kNone, 0);
       continue;
     }

     Location location = locations->GetEnvironmentAt(i);
     switch (location.GetKind()) {
       case Location::kConstant: {
         DCHECK(current == location.GetConstant());
         if (current->IsLongConstant()) {
           int64_t value = current->AsLongConstant()->GetValue();
           stack_map_stream_.AddDexRegisterEntry(DexRegisterMap::kConstant, Low32Bits(value));
           stack_map_stream_.AddDexRegisterEntry(DexRegisterMap::kConstant, High32Bits(value));
           ++i;
           DCHECK_LT(i, environment_size);
         } else {
           DCHECK(current->IsIntConstant());
           int32_t value = current->AsIntConstant()->GetValue();
           stack_map_stream_.AddDexRegisterEntry(DexRegisterMap::kConstant, value);
         }
         break;
       }

       case Location::kStackSlot: {
         stack_map_stream_.AddDexRegisterEntry(DexRegisterMap::kInStack, location.GetStackIndex());
         break;
       }

       case Location::kDoubleStackSlot: {
         stack_map_stream_.AddDexRegisterEntry(DexRegisterMap::kInStack, location.GetStackIndex());
         stack_map_stream_.AddDexRegisterEntry(DexRegisterMap::kInStack,
                                               location.GetHighStackIndex(kVRegSize));
         ++i;
         DCHECK_LT(i, environment_size);
         break;
       }

       case Location::kRegister : {
         int id = location.reg().RegId();
         stack_map_stream_.AddDexRegisterEntry(DexRegisterMap::kInRegister, id);
         if (current->GetType() == Primitive::kPrimDouble
             || current->GetType() == Primitive::kPrimLong) {
           stack_map_stream_.AddDexRegisterEntry(DexRegisterMap::kInRegister, id);
           ++i;
           DCHECK_LT(i, environment_size);
         }
         break;
       }

       default:
         LOG(FATAL) << "Unexpected kind " << location.GetKind();
     }
   }
 }

 size_t CodeGenerator::GetStackOffsetOfSavedRegister(size_t index) {
   return first_register_slot_in_slow_path_ + index * GetWordSize();
 }

 void CodeGenerator::SaveLiveRegisters(LocationSummary* locations) {
   RegisterSet* register_set = locations->GetLiveRegisters();
   uint32_t count = 0;
   for (size_t i = 0, e = GetNumberOfCoreRegisters(); i < e; ++i) {
     if (register_set->ContainsCoreRegister(i)) {
       size_t stack_offset = GetStackOffsetOfSavedRegister(count);
       ++count;
       SaveCoreRegister(Location::StackSlot(stack_offset), i);
       // If the register holds an object, update the stack mask.
       if (locations->RegisterContainsObject(i)) {
         locations->SetStackBit(stack_offset / kVRegSize);
       }
     }
   }

   for (size_t i = 0, e = GetNumberOfFloatingPointRegisters(); i < e; ++i) {
     if (register_set->ContainsFloatingPointRegister(i)) {
       LOG(FATAL) << "Unimplemented";
     }
   }
 }

 void CodeGenerator::RestoreLiveRegisters(LocationSummary* locations) {
   RegisterSet* register_set = locations->GetLiveRegisters();
   uint32_t count = 0;
   for (size_t i = 0, e = GetNumberOfCoreRegisters(); i < e; ++i) {
     if (register_set->ContainsCoreRegister(i)) {
       size_t stack_offset = GetStackOffsetOfSavedRegister(count);
       ++count;
       RestoreCoreRegister(Location::StackSlot(stack_offset), i);
     }
   }

   for (size_t i = 0, e = GetNumberOfFloatingPointRegisters(); i < e; ++i) {
     if (register_set->ContainsFloatingPointRegister(i)) {
       LOG(FATAL) << "Unimplemented";
     }
   }
 }

 void CodeGenerator::ClearSpillSlotsFromLoopPhisInStackMap(HSuspendCheck* suspend_check) const {
   LocationSummary* locations = suspend_check->GetLocations();
   HBasicBlock* block = suspend_check->GetBlock();
   DCHECK(block->GetLoopInformation()->GetSuspendCheck() == suspend_check);
   DCHECK(block->IsLoopHeader());

   for (HInstructionIterator it(block->GetPhis()); !it.Done(); it.Advance()) {
     HInstruction* current = it.Current();
     LiveInterval* interval = current->GetLiveInterval();
     // We only need to clear bits of loop phis containing objects and allocated in register.
     // Loop phis allocated on stack already have the object in the stack.
     if (current->GetType() == Primitive::kPrimNot
         && interval->HasRegister()
         && interval->HasSpillSlot()) {
       locations->ClearStackBit(interval->GetSpillSlot() / kVRegSize);
     }
   }
 }

 }  // namespace art
	/*
	* Copyright (C) 2014 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	#include "code_generator.h"

	#include "code_generator_arm.h"
	#include "code_generator_x86.h"
	#include "code_generator_x86_64.h"
	#include "compiled_method.h"
	#include "dex/verified_method.h"
	#include "driver/dex_compilation_unit.h"
	#include "gc_map_builder.h"
	#include "leb128.h"
	#include "mapping_table.h"
	#include "ssa_liveness_analysis.h"
	#include "utils/assembler.h"
	#include "verifier/dex_gc_map.h"
	#include "vmap_table.h"

	namespace art {

	void CodeGenerator::CompileBaseline(CodeAllocator* allocator, bool is_leaf) {
	const GrowableArray<HBasicBlock*>& blocks = GetGraph()->GetBlocks();
	DCHECK(blocks.Get(0) == GetGraph()->GetEntryBlock());
	DCHECK(GoesToNextBlock(GetGraph()->GetEntryBlock(), blocks.Get(1)));
	block_labels_.SetSize(blocks.Size());

	DCHECK_EQ(frame_size_, kUninitializedFrameSize);
	if (!is_leaf) {
	MarkNotLeaf();
	}
	ComputeFrameSize(GetGraph()->GetNumberOfLocalVRegs()
	+ GetGraph()->GetNumberOfTemporaries()
	+ 1 /* filler */,
	0, /* the baseline compiler does not have live registers at slow path */
	GetGraph()->GetMaximumNumberOfOutVRegs()
	+ 1 /* current method */);
	GenerateFrameEntry();

	HGraphVisitor* location_builder = GetLocationBuilder();
	HGraphVisitor* instruction_visitor = GetInstructionVisitor();
	for (size_t i = 0, e = blocks.Size(); i < e; ++i) {
	HBasicBlock* block = blocks.Get(i);
	Bind(GetLabelOf(block));
	for (HInstructionIterator it(block->GetInstructions()); !it.Done(); it.Advance()) {
	HInstruction* current = it.Current();
	current->Accept(location_builder);
	InitLocations(current);
	current->Accept(instruction_visitor);
	}
	}
	GenerateSlowPaths();

	size_t code_size = GetAssembler()->CodeSize();
	uint8_t* buffer = allocator->Allocate(code_size);
	MemoryRegion code(buffer, code_size);
	GetAssembler()->FinalizeInstructions(code);
	}

	void CodeGenerator::CompileOptimized(CodeAllocator* allocator) {
	// The frame size has already been computed during register allocation.
	DCHECK_NE(frame_size_, kUninitializedFrameSize);
	const GrowableArray<HBasicBlock*>& blocks = GetGraph()->GetBlocks();
	DCHECK(blocks.Get(0) == GetGraph()->GetEntryBlock());
	DCHECK(GoesToNextBlock(GetGraph()->GetEntryBlock(), blocks.Get(1)));
	block_labels_.SetSize(blocks.Size());

	GenerateFrameEntry();
	HGraphVisitor* instruction_visitor = GetInstructionVisitor();
	for (size_t i = 0, e = blocks.Size(); i < e; ++i) {
	HBasicBlock* block = blocks.Get(i);
	Bind(GetLabelOf(block));
	for (HInstructionIterator it(block->GetInstructions()); !it.Done(); it.Advance()) {
	HInstruction* current = it.Current();
	current->Accept(instruction_visitor);
	}
	}
	GenerateSlowPaths();

	size_t code_size = GetAssembler()->CodeSize();
	uint8_t* buffer = allocator->Allocate(code_size);
	MemoryRegion code(buffer, code_size);
	GetAssembler()->FinalizeInstructions(code);
	}

	void CodeGenerator::GenerateSlowPaths() {
	for (size_t i = 0, e = slow_paths_.Size(); i < e; ++i) {
	slow_paths_.Get(i)->EmitNativeCode(this);
	}
	}

	size_t CodeGenerator::AllocateFreeRegisterInternal(
	bool* blocked_registers, size_t number_of_registers) const {
	for (size_t regno = 0; regno < number_of_registers; regno++) {
	if (!blocked_registers[regno]) {
	blocked_registers[regno] = true;
	return regno;
	}
	}
	return -1;
	}

	void CodeGenerator::ComputeFrameSize(size_t number_of_spill_slots,
	size_t maximum_number_of_live_registers,
	size_t number_of_out_slots) {
	first_register_slot_in_slow_path_ = (number_of_out_slots + number_of_spill_slots) * kVRegSize;

	SetFrameSize(RoundUp(
	number_of_spill_slots * kVRegSize
	+ number_of_out_slots * kVRegSize
	+ maximum_number_of_live_registers * GetWordSize()
	+ FrameEntrySpillSize(),
	kStackAlignment));
	}

	Location CodeGenerator::GetTemporaryLocation(HTemporary* temp) const {
	uint16_t number_of_locals = GetGraph()->GetNumberOfLocalVRegs();
	// Use the temporary region (right below the dex registers).
	int32_t slot = GetFrameSize() - FrameEntrySpillSize()
	- kVRegSize // filler
	- (number_of_locals * kVRegSize)
	- ((1 + temp->GetIndex()) * kVRegSize);
	return Location::StackSlot(slot);
	}

	int32_t CodeGenerator::GetStackSlot(HLocal* local) const {
	uint16_t reg_number = local->GetRegNumber();
	uint16_t number_of_locals = GetGraph()->GetNumberOfLocalVRegs();
	if (reg_number >= number_of_locals) {
	// Local is a parameter of the method. It is stored in the caller's frame.
	return GetFrameSize() + kVRegSize // ART method
	+ (reg_number - number_of_locals) * kVRegSize;
	} else {
	// Local is a temporary in this method. It is stored in this method's frame.
	return GetFrameSize() - FrameEntrySpillSize()
	- kVRegSize // filler.
	- (number_of_locals * kVRegSize)
	+ (reg_number * kVRegSize);
	}
	}

	void CodeGenerator::AllocateRegistersLocally(HInstruction* instruction) const {
	LocationSummary* locations = instruction->GetLocations();
	if (locations == nullptr) return;

	for (size_t i = 0, e = GetNumberOfRegisters(); i < e; ++i) {
	blocked_registers_[i] = false;
	}

	// Mark all fixed input, temp and output registers as used.
	for (size_t i = 0, e = locations->GetInputCount(); i < e; ++i) {
	Location loc = locations->InAt(i);
	if (loc.IsRegister()) {
	// Check that a register is not specified twice in the summary.
	DCHECK(!blocked_registers_[loc.GetEncoding()]);
	blocked_registers_[loc.GetEncoding()] = true;
	}
	}

	for (size_t i = 0, e = locations->GetTempCount(); i < e; ++i) {
	Location loc = locations->GetTemp(i);
	if (loc.IsRegister()) {
	// Check that a register is not specified twice in the summary.
	DCHECK(!blocked_registers_[loc.GetEncoding()]);
	blocked_registers_[loc.GetEncoding()] = true;
	}
	}

	SetupBlockedRegisters(blocked_registers_);

	// Allocate all unallocated input locations.
	for (size_t i = 0, e = locations->GetInputCount(); i < e; ++i) {
	Location loc = locations->InAt(i);
	HInstruction* input = instruction->InputAt(i);
	if (loc.IsUnallocated()) {
	if (loc.GetPolicy() == Location::kRequiresRegister) {
	loc = Location::RegisterLocation(
	AllocateFreeRegister(input->GetType(), blocked_registers_));
	} else {
	DCHECK_EQ(loc.GetPolicy(), Location::kAny);
	HLoadLocal* load = input->AsLoadLocal();
	if (load != nullptr) {
	loc = GetStackLocation(load);
	} else {
	loc = Location::RegisterLocation(
	AllocateFreeRegister(input->GetType(), blocked_registers_));
	}
	}
	locations->SetInAt(i, loc);
	}
	}

	// Allocate all unallocated temp locations.
	for (size_t i = 0, e = locations->GetTempCount(); i < e; ++i) {
	Location loc = locations->GetTemp(i);
	if (loc.IsUnallocated()) {
	DCHECK_EQ(loc.GetPolicy(), Location::kRequiresRegister);
	// TODO: Adjust handling of temps. We currently consider temps to use
	// core registers. They may also use floating point registers at some point.
	loc = Location::RegisterLocation(static_cast<ManagedRegister>(
	AllocateFreeRegister(Primitive::kPrimInt, blocked_registers_)));
	locations->SetTempAt(i, loc);
	}
	}
	Location result_location = locations->Out();
	if (result_location.IsUnallocated()) {
	switch (result_location.GetPolicy()) {
	case Location::kAny:
	case Location::kRequiresRegister:
	result_location = Location::RegisterLocation(
	AllocateFreeRegister(instruction->GetType(), blocked_registers_));
	break;
	case Location::kSameAsFirstInput:
	result_location = locations->InAt(0);
	break;
	}
	locations->SetOut(result_location);
	}
	}

	void CodeGenerator::InitLocations(HInstruction* instruction) {
	if (instruction->GetLocations() == nullptr) {
	if (instruction->IsTemporary()) {
	HInstruction* previous = instruction->GetPrevious();
	Location temp_location = GetTemporaryLocation(instruction->AsTemporary());
	Move(previous, temp_location, instruction);
	previous->GetLocations()->SetOut(temp_location);
	}
	return;
	}
	AllocateRegistersLocally(instruction);
	for (size_t i = 0, e = instruction->InputCount(); i < e; ++i) {
	Location location = instruction->GetLocations()->InAt(i);
	if (location.IsValid()) {
	// Move the input to the desired location.
	Move(instruction->InputAt(i), location, instruction);
	}
	}
	}

	bool CodeGenerator::GoesToNextBlock(HBasicBlock* current, HBasicBlock* next) const {
	// We currently iterate over the block in insertion order.
	return current->GetBlockId() + 1 == next->GetBlockId();
	}

	Label* CodeGenerator::GetLabelOf(HBasicBlock* block) const {
	return block_labels_.GetRawStorage() + block->GetBlockId();
	}

	CodeGenerator* CodeGenerator::Create(ArenaAllocator* allocator,
	HGraph* graph,
	InstructionSet instruction_set) {
	switch (instruction_set) {
	case kArm:
	case kThumb2: {
	return new (allocator) arm::CodeGeneratorARM(graph);
	}
	case kMips:
	return nullptr;
	case kX86: {
	return new (allocator) x86::CodeGeneratorX86(graph);
	}
	case kX86_64: {
	return new (allocator) x86_64::CodeGeneratorX86_64(graph);
	}
	default:
	return nullptr;
	}
	}

	void CodeGenerator::BuildNativeGCMap(
	std::vector<uint8_t>* data, const DexCompilationUnit& dex_compilation_unit) const {
	const std::vector<uint8_t>& gc_map_raw =
	dex_compilation_unit.GetVerifiedMethod()->GetDexGcMap();
	verifier::DexPcToReferenceMap dex_gc_map(&(gc_map_raw)[0]);

	uint32_t max_native_offset = 0;
	for (size_t i = 0; i < pc_infos_.Size(); i++) {
	uint32_t native_offset = pc_infos_.Get(i).native_pc;
	if (native_offset > max_native_offset) {
	max_native_offset = native_offset;
	}
	}

	GcMapBuilder builder(data, pc_infos_.Size(), max_native_offset, dex_gc_map.RegWidth());
	for (size_t i = 0; i < pc_infos_.Size(); i++) {
	struct PcInfo pc_info = pc_infos_.Get(i);
	uint32_t native_offset = pc_info.native_pc;
	uint32_t dex_pc = pc_info.dex_pc;
	const uint8_t* references = dex_gc_map.FindBitMap(dex_pc, false);
	CHECK(references != NULL) << "Missing ref for dex pc 0x" << std::hex << dex_pc;
	builder.AddEntry(native_offset, references);
	}
	}

	void CodeGenerator::BuildMappingTable(std::vector<uint8_t>* data, SrcMap* src_map) const {
	uint32_t pc2dex_data_size = 0u;
	uint32_t pc2dex_entries = pc_infos_.Size();
	uint32_t pc2dex_offset = 0u;
	int32_t pc2dex_dalvik_offset = 0;
	uint32_t dex2pc_data_size = 0u;
	uint32_t dex2pc_entries = 0u;

	if (src_map != nullptr) {
	src_map->reserve(pc2dex_entries);
	}

	// We currently only have pc2dex entries.
	for (size_t i = 0; i < pc2dex_entries; i++) {
	struct PcInfo pc_info = pc_infos_.Get(i);
	pc2dex_data_size += UnsignedLeb128Size(pc_info.native_pc - pc2dex_offset);
	pc2dex_data_size += SignedLeb128Size(pc_info.dex_pc - pc2dex_dalvik_offset);
	pc2dex_offset = pc_info.native_pc;
	pc2dex_dalvik_offset = pc_info.dex_pc;
	if (src_map != nullptr) {
	src_map->push_back(SrcMapElem({pc2dex_offset, pc2dex_dalvik_offset}));
	}
	}

	uint32_t total_entries = pc2dex_entries + dex2pc_entries;
	uint32_t hdr_data_size = UnsignedLeb128Size(total_entries) + UnsignedLeb128Size(pc2dex_entries);
	uint32_t data_size = hdr_data_size + pc2dex_data_size + dex2pc_data_size;
	data->resize(data_size);

	uint8_t* data_ptr = &(*data)[0];
	uint8_t* write_pos = data_ptr;
	write_pos = EncodeUnsignedLeb128(write_pos, total_entries);
	write_pos = EncodeUnsignedLeb128(write_pos, pc2dex_entries);
	DCHECK_EQ(static_cast<size_t>(write_pos - data_ptr), hdr_data_size);
	uint8_t* write_pos2 = write_pos + pc2dex_data_size;

	pc2dex_offset = 0u;
	pc2dex_dalvik_offset = 0u;
	for (size_t i = 0; i < pc2dex_entries; i++) {
	struct PcInfo pc_info = pc_infos_.Get(i);
	DCHECK(pc2dex_offset <= pc_info.native_pc);
	write_pos = EncodeUnsignedLeb128(write_pos, pc_info.native_pc - pc2dex_offset);
	write_pos = EncodeSignedLeb128(write_pos, pc_info.dex_pc - pc2dex_dalvik_offset);
	pc2dex_offset = pc_info.native_pc;
	pc2dex_dalvik_offset = pc_info.dex_pc;
	}
	DCHECK_EQ(static_cast<size_t>(write_pos - data_ptr), hdr_data_size + pc2dex_data_size);
	DCHECK_EQ(static_cast<size_t>(write_pos2 - data_ptr), data_size);

	if (kIsDebugBuild) {
	// Verify the encoded table holds the expected data.
	MappingTable table(data_ptr);
	CHECK_EQ(table.TotalSize(), total_entries);
	CHECK_EQ(table.PcToDexSize(), pc2dex_entries);
	auto it = table.PcToDexBegin();
	auto it2 = table.DexToPcBegin();
	for (size_t i = 0; i < pc2dex_entries; i++) {
	struct PcInfo pc_info = pc_infos_.Get(i);
	CHECK_EQ(pc_info.native_pc, it.NativePcOffset());
	CHECK_EQ(pc_info.dex_pc, it.DexPc());
	++it;
	}
	CHECK(it == table.PcToDexEnd());
	CHECK(it2 == table.DexToPcEnd());
	}
	}

	void CodeGenerator::BuildVMapTable(std::vector<uint8_t>* data) const {
	Leb128EncodingVector vmap_encoder;
	// We currently don't use callee-saved registers.
	size_t size = 0 + 1 /* marker */ + 0;
	vmap_encoder.Reserve(size + 1u); // All values are likely to be one byte in ULEB128 (<128).
	vmap_encoder.PushBackUnsigned(size);
	vmap_encoder.PushBackUnsigned(VmapTable::kAdjustedFpMarker);

	*data = vmap_encoder.GetData();
	}

	void CodeGenerator::BuildStackMaps(std::vector<uint8_t>* data) {
	uint32_t size = stack_map_stream_.ComputeNeededSize();
	data->resize(size);
	MemoryRegion region(data->data(), size);
	stack_map_stream_.FillIn(region);
	}

	void CodeGenerator::RecordPcInfo(HInstruction* instruction, uint32_t dex_pc) {
	// Collect PC infos for the mapping table.
	struct PcInfo pc_info;
	pc_info.dex_pc = dex_pc;
	pc_info.native_pc = GetAssembler()->CodeSize();
	pc_infos_.Add(pc_info);

	// Populate stack map information.

	if (instruction == nullptr) {
	// For stack overflow checks.
	stack_map_stream_.AddStackMapEntry(dex_pc, pc_info.native_pc, 0, 0, 0, 0);
	return;
	}

	LocationSummary* locations = instruction->GetLocations();
	HEnvironment* environment = instruction->GetEnvironment();

	size_t environment_size = instruction->EnvironmentSize();

	size_t register_mask = 0;
	size_t inlining_depth = 0;
	stack_map_stream_.AddStackMapEntry(
	dex_pc, pc_info.native_pc, register_mask,
	locations->GetStackMask(), environment_size, inlining_depth);

	// Walk over the environment, and record the location of dex registers.
	for (size_t i = 0; i < environment_size; ++i) {
	HInstruction* current = environment->GetInstructionAt(i);
	if (current == nullptr) {
	stack_map_stream_.AddDexRegisterEntry(DexRegisterMap::kNone, 0);
	continue;
	}

	Location location = locations->GetEnvironmentAt(i);
	switch (location.GetKind()) {
	case Location::kConstant: {
	DCHECK(current == location.GetConstant());
	if (current->IsLongConstant()) {
	int64_t value = current->AsLongConstant()->GetValue();
	stack_map_stream_.AddDexRegisterEntry(DexRegisterMap::kConstant, Low32Bits(value));
	stack_map_stream_.AddDexRegisterEntry(DexRegisterMap::kConstant, High32Bits(value));
	++i;
	DCHECK_LT(i, environment_size);
	} else {
	DCHECK(current->IsIntConstant());
	int32_t value = current->AsIntConstant()->GetValue();
	stack_map_stream_.AddDexRegisterEntry(DexRegisterMap::kConstant, value);
	}
	break;
	}

	case Location::kStackSlot: {
	stack_map_stream_.AddDexRegisterEntry(DexRegisterMap::kInStack, location.GetStackIndex());
	break;
	}

	case Location::kDoubleStackSlot: {
	stack_map_stream_.AddDexRegisterEntry(DexRegisterMap::kInStack, location.GetStackIndex());
	stack_map_stream_.AddDexRegisterEntry(DexRegisterMap::kInStack,
	location.GetHighStackIndex(kVRegSize));
	++i;
	DCHECK_LT(i, environment_size);
	break;
	}

	case Location::kRegister : {
	int id = location.reg().RegId();
	stack_map_stream_.AddDexRegisterEntry(DexRegisterMap::kInRegister, id);
	if (current->GetType() == Primitive::kPrimDouble
	\|\| current->GetType() == Primitive::kPrimLong) {
	stack_map_stream_.AddDexRegisterEntry(DexRegisterMap::kInRegister, id);
	++i;
	DCHECK_LT(i, environment_size);
	}
	break;
	}

	default:
	LOG(FATAL) << "Unexpected kind " << location.GetKind();
	}
	}
	}

	size_t CodeGenerator::GetStackOffsetOfSavedRegister(size_t index) {
	return first_register_slot_in_slow_path_ + index * GetWordSize();
	}

	void CodeGenerator::SaveLiveRegisters(LocationSummary* locations) {
	RegisterSet* register_set = locations->GetLiveRegisters();
	uint32_t count = 0;
	for (size_t i = 0, e = GetNumberOfCoreRegisters(); i < e; ++i) {
	if (register_set->ContainsCoreRegister(i)) {
	size_t stack_offset = GetStackOffsetOfSavedRegister(count);
	++count;
	SaveCoreRegister(Location::StackSlot(stack_offset), i);
	// If the register holds an object, update the stack mask.
	if (locations->RegisterContainsObject(i)) {
	locations->SetStackBit(stack_offset / kVRegSize);
	}
	}
	}

	for (size_t i = 0, e = GetNumberOfFloatingPointRegisters(); i < e; ++i) {
	if (register_set->ContainsFloatingPointRegister(i)) {
	LOG(FATAL) << "Unimplemented";
	}
	}
	}

	void CodeGenerator::RestoreLiveRegisters(LocationSummary* locations) {
	RegisterSet* register_set = locations->GetLiveRegisters();
	uint32_t count = 0;
	for (size_t i = 0, e = GetNumberOfCoreRegisters(); i < e; ++i) {
	if (register_set->ContainsCoreRegister(i)) {
	size_t stack_offset = GetStackOffsetOfSavedRegister(count);
	++count;
	RestoreCoreRegister(Location::StackSlot(stack_offset), i);
	}
	}

	for (size_t i = 0, e = GetNumberOfFloatingPointRegisters(); i < e; ++i) {
	if (register_set->ContainsFloatingPointRegister(i)) {
	LOG(FATAL) << "Unimplemented";
	}
	}
	}

	void CodeGenerator::ClearSpillSlotsFromLoopPhisInStackMap(HSuspendCheck* suspend_check) const {
	LocationSummary* locations = suspend_check->GetLocations();
	HBasicBlock* block = suspend_check->GetBlock();
	DCHECK(block->GetLoopInformation()->GetSuspendCheck() == suspend_check);
	DCHECK(block->IsLoopHeader());

	for (HInstructionIterator it(block->GetPhis()); !it.Done(); it.Advance()) {
	HInstruction* current = it.Current();
	LiveInterval* interval = current->GetLiveInterval();
	// We only need to clear bits of loop phis containing objects and allocated in register.
	// Loop phis allocated on stack already have the object in the stack.
	if (current->GetType() == Primitive::kPrimNot
	&& interval->HasRegister()
	&& interval->HasSpillSlot()) {
	locations->ClearStackBit(interval->GetSpillSlot() / kVRegSize);
	}
	}
	}

	} // namespace art