runtime/vm/instructions_x64.h

// Copyright (c) 2012, 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_X64_H_
#define RUNTIME_VM_INSTRUCTIONS_X64_H_

#ifndef RUNTIME_VM_INSTRUCTIONS_H_
#error Do not include instructions_ia32.h directly; use instructions.h instead.
#endif

#include "vm/allocation.h"
#include "vm/object.h"

namespace dart {

// Forward declarations.
class RawClass;
class Immediate;
class RawObject;

intptr_t IndexFromPPLoadDisp8(uword start);
intptr_t IndexFromPPLoadDisp32(uword start);

// Template class for all instruction pattern classes.
// P has to specify a static pattern and a pattern length method.
template <class P>
class InstructionPattern : public ValueObject {
 public:
  explicit InstructionPattern(uword pc) : start_(pc) { ASSERT(pc != 0); }

  // Call to check if the instruction pattern at 'pc' match the instruction.
  // 'P::pattern()' returns the expected byte pattern in form of an integer
  // array with length of 'P::pattern_length_in_bytes()'. A '-1' element means
  // 'any byte'.
  bool IsValid() const {
    return TestBytesWith(P::pattern(), P::pattern_length_in_bytes());
  }

 protected:
  uword start() const { return start_; }

 private:
  // Returns true if the 'num_bytes' bytes at 'start_' correspond to
  // array of integers 'data'. 'data' elements are either a byte or -1, which
  // represents any byte.
  bool TestBytesWith(const int* data, int num_bytes) const {
    ASSERT(data != NULL);
    const uint8_t* byte_array = reinterpret_cast<const uint8_t*>(start_);
    for (int i = 0; i < num_bytes; i++) {
      // Skip comparison for data[i] < 0.
      if ((data[i] >= 0) && (byte_array[i] != (0xFF & data[i]))) {
        return false;
      }
    }
    return true;
  }

  const uword start_;

  DISALLOW_COPY_AND_ASSIGN(InstructionPattern);
};

class ReturnPattern : public InstructionPattern<ReturnPattern> {
 public:
  explicit ReturnPattern(uword pc) : InstructionPattern(pc) {}

  static const int* pattern() {
    static const int kReturnPattern[kLengthInBytes] = {0xC3};
    return kReturnPattern;
  }

  static int pattern_length_in_bytes() { return kLengthInBytes; }

 private:
  static const int kLengthInBytes = 1;
};

// push rbp
// mov rbp, rsp
class ProloguePattern : public InstructionPattern<ProloguePattern> {
 public:
  explicit ProloguePattern(uword pc) : InstructionPattern(pc) {}

  static const int* pattern() {
    static const int kProloguePattern[kLengthInBytes] = {0x55, 0x48, 0x89,
                                                         0xe5};
    return kProloguePattern;
  }

  static int pattern_length_in_bytes() { return kLengthInBytes; }

 private:
  static const int kLengthInBytes = 4;
};

// mov rbp, rsp
class SetFramePointerPattern
    : public InstructionPattern<SetFramePointerPattern> {
 public:
  explicit SetFramePointerPattern(uword pc) : InstructionPattern(pc) {}

  static const int* pattern() {
    static const int kFramePointerPattern[kLengthInBytes] = {0x48, 0x89, 0xe5};
    return kFramePointerPattern;
  }

  static int pattern_length_in_bytes() { return kLengthInBytes; }

 private:
  static const int kLengthInBytes = 3;
};

// callq *[rip+offset]
class PcRelativeCallPattern : public InstructionPattern<PcRelativeCallPattern> {
 public:
  explicit PcRelativeCallPattern(uword pc) : InstructionPattern(pc) {}

  int32_t distance() {
    return *reinterpret_cast<int32_t*>(start() + 1) + kLengthInBytes;
  }

  void set_distance(int32_t distance) {
    // [distance] is relative to the start of the instruction, x64 considers the
    // offset relative to next PC.
    *reinterpret_cast<int32_t*>(start() + 1) = distance - kLengthInBytes;
  }

  static const int* pattern() {
    static const int kPattern[kLengthInBytes] = {0xe8, -1, -1, -1, -1};
    return kPattern;
  }

  static int pattern_length_in_bytes() { return kLengthInBytes; }

  static const int kLengthInBytes = 5;
};

// jmpq *[rip+offset]
class PcRelativeJumpPattern : public InstructionPattern<PcRelativeJumpPattern> {
 public:
  explicit PcRelativeJumpPattern(uword pc) : InstructionPattern(pc) {}

  int32_t distance() {
    return *reinterpret_cast<int32_t*>(start() + 2) + kLengthInBytes;
  }

  void set_distance(int32_t distance) {
    // [distance] is relative to the start of the instruction, x64 considers the
    // offset relative to next PC.
    *reinterpret_cast<int32_t*>(start() + 2) = distance - kLengthInBytes;
  }

  static const int* pattern() {
    static const int kPattern[kLengthInBytes] = {0xff, 0x25, -1, -1, -1, -1};
    return kPattern;
  }

  static int pattern_length_in_bytes() { return kLengthInBytes; }

  static const int kLengthInBytes = 6;
};

}  // namespace dart

#endif  // RUNTIME_VM_INSTRUCTIONS_X64_H_