compiler/optimizing/code_generator.h

/*
 * 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.
 */

#ifndef ART_COMPILER_OPTIMIZING_CODE_GENERATOR_H_
#define ART_COMPILER_OPTIMIZING_CODE_GENERATOR_H_

#include "base/bit_field.h"
#include "globals.h"
#include "instruction_set.h"
#include "locations.h"
#include "memory_region.h"
#include "nodes.h"
#include "utils/assembler.h"

namespace art {

static size_t constexpr kVRegSize = 4;
static size_t constexpr kUninitializedFrameSize = 0;

class DexCompilationUnit;

class CodeAllocator {
 public:
  CodeAllocator() { }
  virtual ~CodeAllocator() { }

  virtual uint8_t* Allocate(size_t size) = 0;

 private:
  DISALLOW_COPY_AND_ASSIGN(CodeAllocator);
};

struct PcInfo {
  uint32_t dex_pc;
  uintptr_t native_pc;
};

class CodeGenerator : public ArenaObject {
 public:
  // Compiles the graph to executable instructions. Returns whether the compilation
  // succeeded.
  void CompileBaseline(CodeAllocator* allocator);
  void CompileOptimized(CodeAllocator* allocator);
  static CodeGenerator* Create(ArenaAllocator* allocator,
                               HGraph* graph,
                               InstructionSet instruction_set);

  HGraph* GetGraph() const { return graph_; }

  Label* GetLabelOf(HBasicBlock* block) const;
  bool GoesToNextBlock(HBasicBlock* current, HBasicBlock* next) const;

  size_t GetStackSlotOfParameter(HParameterValue* parameter) const {
    // Note that this follows the current calling convention.
    return GetFrameSize()
        + kVRegSize  // Art method
        + parameter->GetIndex() * kVRegSize;
  }

  virtual void GenerateFrameEntry() = 0;
  virtual void GenerateFrameExit() = 0;
  virtual void Bind(Label* label) = 0;
  virtual void Move(HInstruction* instruction, Location location, HInstruction* move_for) = 0;
  virtual HGraphVisitor* GetLocationBuilder() = 0;
  virtual HGraphVisitor* GetInstructionVisitor() = 0;
  virtual Assembler* GetAssembler() = 0;
  virtual size_t GetWordSize() const = 0;
  virtual void ComputeFrameSize(size_t number_of_spill_slots) = 0;

  uint32_t GetFrameSize() const { return frame_size_; }
  void SetFrameSize(uint32_t size) { frame_size_ = size; }
  uint32_t GetCoreSpillMask() const { return core_spill_mask_; }

  virtual size_t GetNumberOfCoreRegisters() const = 0;
  virtual size_t GetNumberOfFloatingPointRegisters() const = 0;
  virtual size_t GetNumberOfRegisters() const = 0;
  virtual void SetupBlockedRegisters(bool* blocked_registers) const = 0;
  virtual void DumpCoreRegister(std::ostream& stream, int reg) const = 0;
  virtual void DumpFloatingPointRegister(std::ostream& stream, int reg) const = 0;

  void RecordPcInfo(uint32_t dex_pc) {
    struct PcInfo pc_info;
    pc_info.dex_pc = dex_pc;
    pc_info.native_pc = GetAssembler()->CodeSize();
    pc_infos_.Add(pc_info);
  }

  void BuildMappingTable(std::vector<uint8_t>* vector) const;
  void BuildVMapTable(std::vector<uint8_t>* vector) const;
  void BuildNativeGCMap(
      std::vector<uint8_t>* vector, const DexCompilationUnit& dex_compilation_unit) const;

 protected:
  CodeGenerator(HGraph* graph, size_t number_of_registers)
      : frame_size_(kUninitializedFrameSize),
        graph_(graph),
        block_labels_(graph->GetArena(), 0),
        pc_infos_(graph->GetArena(), 32),
        blocked_registers_(graph->GetArena()->AllocArray<bool>(number_of_registers)) {}
  ~CodeGenerator() {}

  // Register allocation logic.
  void AllocateRegistersLocally(HInstruction* instruction) const;

  // Backend specific implementation for allocating a register.
  virtual ManagedRegister AllocateFreeRegister(Primitive::Type type,
                                               bool* blocked_registers) const = 0;

  // Raw implementation of allocating a register: loops over blocked_registers to find
  // the first available register.
  size_t AllocateFreeRegisterInternal(bool* blocked_registers, size_t number_of_registers) const;

  virtual Location GetStackLocation(HLoadLocal* load) const = 0;

  // Frame size required for this method.
  uint32_t frame_size_;
  uint32_t core_spill_mask_;

 private:
  void InitLocations(HInstruction* instruction);

  HGraph* const graph_;

  // Labels for each block that will be compiled.
  GrowableArray<Label> block_labels_;
  GrowableArray<PcInfo> pc_infos_;

  // Temporary data structure used when doing register allocation.
  bool* const blocked_registers_;

  DISALLOW_COPY_AND_ASSIGN(CodeGenerator);
};

template <typename T>
class CallingConvention {
 public:
  CallingConvention(const T* registers, int number_of_registers)
      : registers_(registers), number_of_registers_(number_of_registers) {}

  size_t GetNumberOfRegisters() const { return number_of_registers_; }

  T GetRegisterAt(size_t index) const {
    DCHECK_LT(index, number_of_registers_);
    return registers_[index];
  }

  uint8_t GetStackOffsetOf(size_t index, size_t word_size) const {
    // We still reserve the space for parameters passed by registers.
    // Add word_size for the method pointer.
    return index * kVRegSize + word_size;
  }

 private:
  const T* registers_;
  const size_t number_of_registers_;

  DISALLOW_COPY_AND_ASSIGN(CallingConvention);
};

}  // namespace art

#endif  // ART_COMPILER_OPTIMIZING_CODE_GENERATOR_H_