runtime/vm/instructions_arm.h

// 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.
// Classes that describe assembly patterns as used by inline caches.

#ifndef RUNTIME_VM_INSTRUCTIONS_ARM_H_
#define RUNTIME_VM_INSTRUCTIONS_ARM_H_

#ifndef RUNTIME_VM_INSTRUCTIONS_H_
#error Do not include instructions_arm.h directly; use instructions.h instead.
#endif

#include "vm/constants_arm.h"
#include "vm/native_entry.h"
#include "vm/object.h"

namespace dart {

class InstructionPattern : public AllStatic {
 public:
  // Decodes a load sequence ending at 'end' (the last instruction of the
  // load sequence is the instruction before the one at end).  Returns the
  // address of the first instruction in the sequence.  Returns the register
  // being loaded and the loaded object in the output parameters 'reg' and
  // 'obj' respectively.
  static uword DecodeLoadObject(uword end,
                                const ObjectPool& object_pool,
                                Register* reg,
                                Object* obj);

  // Decodes a load sequence ending at 'end' (the last instruction of the
  // load sequence is the instruction before the one at end).  Returns the
  // address of the first instruction in the sequence.  Returns the register
  // being loaded and the loaded immediate value in the output parameters
  // 'reg' and 'value' respectively.
  static uword DecodeLoadWordImmediate(uword end,
                                       Register* reg,
                                       intptr_t* value);

  // Decodes a load sequence ending at 'end' (the last instruction of the
  // load sequence is the instruction before the one at end).  Returns the
  // address of the first instruction in the sequence.  Returns the register
  // being loaded and the index in the pool being read from in the output
  // parameters 'reg' and 'index' respectively.
  // IMPORANT: When generating code loading values from pool on ARM use
  // LoadWordFromPool macro instruction instead of emitting direct load.
  // The macro instruction takes care of pool offsets that can't be
  // encoded as immediates.
  static uword DecodeLoadWordFromPool(uword end,
                                      Register* reg,
                                      intptr_t* index);
};

class CallPattern : public ValueObject {
 public:
  CallPattern(uword pc, const Code& code);

  RawICData* IcData();

  RawCode* TargetCode() const;
  void SetTargetCode(const Code& code) const;

 private:
  const ObjectPool& object_pool_;

  uword end_;
  uword ic_data_load_end_;

  intptr_t target_code_pool_index_;
  ICData& ic_data_;

  DISALLOW_COPY_AND_ASSIGN(CallPattern);
};

class NativeCallPattern : public ValueObject {
 public:
  NativeCallPattern(uword pc, const Code& code);

  RawCode* target() const;
  void set_target(const Code& target) const;

  NativeFunction native_function() const;
  void set_native_function(NativeFunction target) const;

 private:
  const ObjectPool& object_pool_;

  uword end_;
  intptr_t native_function_pool_index_;
  intptr_t target_code_pool_index_;

  DISALLOW_COPY_AND_ASSIGN(NativeCallPattern);
};

// Instance call that can switch between a direct monomorphic call, an IC call,
// and a megamorphic call.
//   load guarded cid            load ICData             load MegamorphicCache
//   load monomorphic target <-> load ICLookup stub  ->  load MMLookup stub
//   call target.entry           call stub.entry         call stub.entry
class SwitchableCallPatternBase : public ValueObject {
 public:
  explicit SwitchableCallPatternBase(const Code& code);

  RawObject* data() const;
  void SetData(const Object& data) const;

 protected:
  const ObjectPool& object_pool_;
  intptr_t data_pool_index_;
  intptr_t target_pool_index_;

 private:
  DISALLOW_COPY_AND_ASSIGN(SwitchableCallPatternBase);
};

// See [SwitchableCallBase] for a switchable calls in general.
//
// The target slot is always a [Code] object: Either the code of the
// monomorphic function or a stub code.
class SwitchableCallPattern : public SwitchableCallPatternBase {
 public:
  SwitchableCallPattern(uword pc, const Code& code);

  RawCode* target() const;
  void SetTarget(const Code& target) const;

 private:
  DISALLOW_COPY_AND_ASSIGN(SwitchableCallPattern);
};

// See [SwitchableCallBase] for a switchable calls in general.
//
// The target slot is always a direct entrypoint address: Either the entry point
// of the monomorphic function or a stub entry point.
class BareSwitchableCallPattern : public SwitchableCallPatternBase {
 public:
  BareSwitchableCallPattern(uword pc, const Code& code);

  RawCode* target() const;
  void SetTarget(const Code& target) const;

 private:
  DISALLOW_COPY_AND_ASSIGN(BareSwitchableCallPattern);
};

class ReturnPattern : public ValueObject {
 public:
  explicit ReturnPattern(uword pc);

  // bx_lr = 1.
  static const int kLengthInBytes = 1 * Instr::kInstrSize;

  int pattern_length_in_bytes() const { return kLengthInBytes; }

  bool IsValid() const;

 private:
  const uword pc_;
};

class PcRelativeCallPattern : public ValueObject {
 public:
  explicit PcRelativeCallPattern(uword pc) : pc_(pc) {}

  static const int kLengthInBytes = 1 * Instr::kInstrSize;

  int32_t distance() {
#if !defined(DART_PRECOMPILED_RUNTIME)
    return Assembler::DecodeBranchOffset(*reinterpret_cast<int32_t*>(pc_));
#else
    UNREACHABLE();
    return 0;
#endif
  }

  void set_distance(int32_t distance) {
#if !defined(DART_PRECOMPILED_RUNTIME)
    int32_t* word = reinterpret_cast<int32_t*>(pc_);
    *word = Assembler::EncodeBranchOffset(distance, *word);
#else
    UNREACHABLE();
#endif
  }

  bool IsValid() const;

 private:
  uword pc_;
};

class PcRelativeJumpPattern : public ValueObject {
 public:
  explicit PcRelativeJumpPattern(uword pc) : pc_(pc) {}

  static const int kLengthInBytes = 1 * Instr::kInstrSize;

  int32_t distance() {
#if !defined(DART_PRECOMPILED_RUNTIME)
    return Assembler::DecodeBranchOffset(*reinterpret_cast<int32_t*>(pc_));
#else
    UNREACHABLE();
    return 0;
#endif
  }

  void set_distance(int32_t distance) {
#if !defined(DART_PRECOMPILED_RUNTIME)
    int32_t* word = reinterpret_cast<int32_t*>(pc_);
    *word = Assembler::EncodeBranchOffset(distance, *word);
#else
    UNREACHABLE();
#endif
  }

  bool IsValid() const;

 private:
  uword pc_;
};

}  // namespace dart

#endif  // RUNTIME_VM_INSTRUCTIONS_ARM_H_