Class HiddenApiAccessFlags

Bcore/src/main/cpp/dex/hidden_api_access_flags.h:58–146

This class is used for encoding and decoding access flags of class members * from the boot class path. These access flags might contain additional two bits * of information on whether the given class member should be hidden from apps * and under what circumstances. * * The encoding is different inside DexFile, where we are concerned with size, * and at runtime where we want to optimize for s

 *
 */
class HiddenApiAccessFlags {
 public:
  enum ApiList {
    kWhitelist = 0,
    kLightGreylist,
    kDarkGreylist,
    kBlacklist,
  };

  static ALWAYS_INLINE ApiList DecodeFromDex(uint32_t dex_access_flags) {
    DexHiddenAccessFlags flags(dex_access_flags);
    uint32_t int_value = (flags.IsFirstBitSet() ? 1 : 0) + (flags.IsSecondBitSet() ? 2 : 0);
    return static_cast<ApiList>(int_value);
  }

  static ALWAYS_INLINE uint32_t RemoveFromDex(uint32_t dex_access_flags) {
    DexHiddenAccessFlags flags(dex_access_flags);
    flags.SetFirstBit(false);
    flags.SetSecondBit(false);
    return flags.GetEncoding();
  }

  static ALWAYS_INLINE uint32_t EncodeForDex(uint32_t dex_access_flags, ApiList value) {
    DexHiddenAccessFlags flags(RemoveFromDex(dex_access_flags));
    uint32_t int_value = static_cast<uint32_t>(value);
    flags.SetFirstBit((int_value & 1) != 0);
    flags.SetSecondBit((int_value & 2) != 0);
    return flags.GetEncoding();
  }

  static ALWAYS_INLINE ApiList DecodeFromRuntime(uint32_t runtime_access_flags) {
    // This is used in the fast path, only DCHECK here.
    DCHECK_EQ(runtime_access_flags & kAccIntrinsic, 0u);
    uint32_t int_value = (runtime_access_flags & kAccHiddenApiBits) >> kAccFlagsShift;
    return static_cast<ApiList>(int_value);
  }

  static ALWAYS_INLINE uint32_t EncodeForRuntime(uint32_t runtime_access_flags, ApiList value) {
    CHECK_EQ(runtime_access_flags & kAccIntrinsic, 0u);

    uint32_t hidden_api_flags = static_cast<uint32_t>(value) << kAccFlagsShift;
    CHECK_EQ(hidden_api_flags & ~kAccHiddenApiBits, 0u);

    runtime_access_flags &= ~kAccHiddenApiBits;
    return runtime_access_flags | hidden_api_flags;
  }

 private:
  static const int kAccFlagsShift = CTZ(kAccHiddenApiBits);
  static_assert(IsPowerOfTwo((kAccHiddenApiBits >> kAccFlagsShift) + 1),
                "kAccHiddenApiBits are not continuous");

  struct DexHiddenAccessFlags {
    explicit DexHiddenAccessFlags(uint32_t access_flags) : access_flags_(access_flags) {}

    ALWAYS_INLINE uint32_t GetSecondFlag() {
      return ((access_flags_ & kAccNative) != 0) ? kAccDexHiddenBitNative : kAccDexHiddenBit;
    }