+/// \brief The behavior an operation has on an input of 0.
+enum ZeroBehavior {
+ /// \brief The returned value is undefined.
+ ZB_Undefined,
+ /// \brief The returned value is numeric_limits<T>::max()
+ ZB_Max,
+ /// \brief The returned value is numeric_limits<T>::digits
+ ZB_Width
+};
+
+/// \brief Count number of 0's from the least significant bit to the most
+/// stopping at the first 1.
+///
+/// Only unsigned integral types are allowed.
+///
+/// \param ZB the behavior on an input of 0. Only ZB_Width and ZB_Undefined are
+/// valid arguments.
+template <typename T>
+typename enable_if_c<std::numeric_limits<T>::is_integer &&
+ !std::numeric_limits<T>::is_signed, std::size_t>::type
+countTrailingZeros(T Val, ZeroBehavior ZB = ZB_Width) {
+ (void)ZB;
+
+ if (!Val)
+ return std::numeric_limits<T>::digits;
+ if (Val & 0x1)
+ return 0;
+
+ // Bisection method.
+ std::size_t ZeroBits = 0;
+ T Shift = std::numeric_limits<T>::digits >> 1;
+ T Mask = std::numeric_limits<T>::max() >> Shift;
+ while (Shift) {
+ if ((Val & Mask) == 0) {
+ Val >>= Shift;
+ ZeroBits |= Shift;
+ }
+ Shift >>= 1;
+ Mask >>= Shift;
+ }
+ return ZeroBits;
+}
+
+// Disable signed.
+template <typename T>
+typename enable_if_c<std::numeric_limits<T>::is_integer &&
+ std::numeric_limits<T>::is_signed, std::size_t>::type
+countTrailingZeros(T Val, ZeroBehavior ZB = ZB_Width) LLVM_DELETED_FUNCTION;
+
+#if __GNUC__ >= 4 || _MSC_VER
+template <>
+inline std::size_t countTrailingZeros<uint32_t>(uint32_t Val, ZeroBehavior ZB) {
+ if (ZB != ZB_Undefined && Val == 0)
+ return 32;
+
+#if __has_builtin(__builtin_ctz) || __GNUC_PREREQ(4, 0)
+ return __builtin_ctz(Val);
+#elif _MSC_VER
+ unsigned long Index;
+ _BitScanForward(&Index, Val);
+ return Index;
+#endif
+}
+
+#if !defined(_MSC_VER) || defined(_M_X64)
+template <>
+inline std::size_t countTrailingZeros<uint64_t>(uint64_t Val, ZeroBehavior ZB) {
+ if (ZB != ZB_Undefined && Val == 0)
+ return 64;
+
+#if __has_builtin(__builtin_ctzll) || __GNUC_PREREQ(4, 0)
+ return __builtin_ctzll(Val);
+#elif _MSC_VER
+ unsigned long Index;
+ _BitScanForward64(&Index, Val);
+ return Index;
+#endif
+}
+#endif
+#endif
+
+/// \brief Count number of 0's from the most significant bit to the least
+/// stopping at the first 1.
+///
+/// Only unsigned integral types are allowed.
+///
+/// \param ZB the behavior on an input of 0. Only ZB_Width and ZB_Undefined are
+/// valid arguments.
+template <typename T>
+typename enable_if_c<std::numeric_limits<T>::is_integer &&
+ !std::numeric_limits<T>::is_signed, std::size_t>::type
+countLeadingZeros(T Val, ZeroBehavior ZB = ZB_Width) {
+ (void)ZB;
+
+ if (!Val)
+ return std::numeric_limits<T>::digits;
+
+ // Bisection method.
+ std::size_t ZeroBits = 0;
+ for (T Shift = std::numeric_limits<T>::digits >> 1; Shift; Shift >>= 1) {
+ T Tmp = Val >> Shift;
+ if (Tmp)
+ Val = Tmp;
+ else
+ ZeroBits |= Shift;
+ }
+ return ZeroBits;
+}
+
+// Disable signed.
+template <typename T>
+typename enable_if_c<std::numeric_limits<T>::is_integer &&
+ std::numeric_limits<T>::is_signed, std::size_t>::type
+countLeadingZeros(T Val, ZeroBehavior ZB = ZB_Width) LLVM_DELETED_FUNCTION;
+
+#if __GNUC__ >= 4 || _MSC_VER
+template <>
+inline std::size_t countLeadingZeros<uint32_t>(uint32_t Val, ZeroBehavior ZB) {
+ if (ZB != ZB_Undefined && Val == 0)
+ return 32;
+
+#if __has_builtin(__builtin_clz) || __GNUC_PREREQ(4, 0)
+ return __builtin_clz(Val);
+#elif _MSC_VER
+ unsigned long Index;
+ _BitScanReverse(&Index, Val);
+ return Index ^ 31;
+#endif
+}
+
+#if !defined(_MSC_VER) || defined(_M_X64)
+template <>
+inline std::size_t countLeadingZeros<uint64_t>(uint64_t Val, ZeroBehavior ZB) {
+ if (ZB != ZB_Undefined && Val == 0)
+ return 64;
+
+#if __has_builtin(__builtin_clzll) || __GNUC_PREREQ(4, 0)
+ return __builtin_clzll(Val);
+#elif _MSC_VER
+ unsigned long Index;
+ _BitScanReverse64(&Index, Val);
+ return Index ^ 63;
+#endif
+}
+#endif
+#endif
+
+/// \brief Get the index of the first set bit starting from the least
+/// significant bit.
+///
+/// Only unsigned integral types are allowed.
+///
+/// \param ZB the behavior on an input of 0. Only ZB_Max and ZB_Undefined are
+/// valid arguments.
+template <typename T>
+typename enable_if_c<std::numeric_limits<T>::is_integer &&
+ !std::numeric_limits<T>::is_signed, T>::type
+findFirstSet(T Val, ZeroBehavior ZB = ZB_Max) {
+ if (ZB == ZB_Max && Val == 0)
+ return std::numeric_limits<T>::max();
+
+ return countTrailingZeros(Val, ZB_Undefined);
+}
+
+// Disable signed.
+template <typename T>
+typename enable_if_c<std::numeric_limits<T>::is_integer &&
+ std::numeric_limits<T>::is_signed, T>::type
+findFirstSet(T Val, ZeroBehavior ZB = ZB_Max) LLVM_DELETED_FUNCTION;
+
+/// \brief Get the index of the last set bit starting from the least
+/// significant bit.
+///
+/// Only unsigned integral types are allowed.
+///
+/// \param ZB the behavior on an input of 0. Only ZB_Max and ZB_Undefined are
+/// valid arguments.
+template <typename T>
+typename enable_if_c<std::numeric_limits<T>::is_integer &&
+ !std::numeric_limits<T>::is_signed, T>::type
+findLastSet(T Val, ZeroBehavior ZB = ZB_Max) {
+ if (ZB == ZB_Max && Val == 0)
+ return std::numeric_limits<T>::max();
+
+ // Use ^ instead of - because both gcc and llvm can remove the associated ^
+ // in the __builtin_clz intrinsic on x86.
+ return countLeadingZeros(Val, ZB_Undefined) ^
+ (std::numeric_limits<T>::digits - 1);
+}
+
+// Disable signed.
+template <typename T>
+typename enable_if_c<std::numeric_limits<T>::is_integer &&
+ std::numeric_limits<T>::is_signed, T>::type
+findLastSet(T Val, ZeroBehavior ZB = ZB_Max) LLVM_DELETED_FUNCTION;
+
+/// \brief Macro compressed bit reversal table for 256 bits.
+///
+/// http://graphics.stanford.edu/~seander/bithacks.html#BitReverseTable
+static const unsigned char BitReverseTable256[256] = {
+#define R2(n) n, n + 2 * 64, n + 1 * 64, n + 3 * 64
+#define R4(n) R2(n), R2(n + 2 * 16), R2(n + 1 * 16), R2(n + 3 * 16)
+#define R6(n) R4(n), R4(n + 2 * 4), R4(n + 1 * 4), R4(n + 3 * 4)
+ R6(0), R6(2), R6(1), R6(3)
+};
+
+/// \brief Reverse the bits in \p Val.
+template <typename T>
+T reverseBits(T Val) {
+ unsigned char in[sizeof(Val)];
+ unsigned char out[sizeof(Val)];
+ std::memcpy(in, &Val, sizeof(Val));
+ for (unsigned i = 0; i < sizeof(Val); ++i)
+ out[(sizeof(Val) - i) - 1] = BitReverseTable256[in[i]];
+ std::memcpy(&Val, out, sizeof(Val));
+ return Val;
+}
+
+// NOTE: The following support functions use the _32/_64 extensions instead of
+// type overloading so that signed and unsigned integers can be used without
+// ambiguity.
+
+/// Hi_32 - This function returns the high 32 bits of a 64 bit value.
+inline uint32_t Hi_32(uint64_t Value) {
+ return static_cast<uint32_t>(Value >> 32);
+}
+
+/// Lo_32 - This function returns the low 32 bits of a 64 bit value.
+inline uint32_t Lo_32(uint64_t Value) {
+ return static_cast<uint32_t>(Value);
+}
+
+/// isInt - Checks if an integer fits into the given bit width.
+template<unsigned N>
+inline bool isInt(int64_t x) {
+ return N >= 64 || (-(INT64_C(1)<<(N-1)) <= x && x < (INT64_C(1)<<(N-1)));
+}
+// Template specializations to get better code for common cases.
+template<>
+inline bool isInt<8>(int64_t x) {
+ return static_cast<int8_t>(x) == x;
+}
+template<>
+inline bool isInt<16>(int64_t x) {
+ return static_cast<int16_t>(x) == x;
+}
+template<>
+inline bool isInt<32>(int64_t x) {
+ return static_cast<int32_t>(x) == x;
+}
+
+/// isShiftedInt<N,S> - Checks if a signed integer is an N bit number shifted
+/// left by S.
+template<unsigned N, unsigned S>
+inline bool isShiftedInt(int64_t x) {
+ return isInt<N+S>(x) && (x % (1<<S) == 0);
+}
+
+/// isUInt - Checks if an unsigned integer fits into the given bit width.
+template<unsigned N>
+inline bool isUInt(uint64_t x) {
+ return N >= 64 || x < (UINT64_C(1)<<(N));
+}
+// Template specializations to get better code for common cases.
+template<>
+inline bool isUInt<8>(uint64_t x) {
+ return static_cast<uint8_t>(x) == x;
+}
+template<>
+inline bool isUInt<16>(uint64_t x) {
+ return static_cast<uint16_t>(x) == x;
+}
+template<>
+inline bool isUInt<32>(uint64_t x) {
+ return static_cast<uint32_t>(x) == x;
+}
+
+/// isShiftedUInt<N,S> - Checks if a unsigned integer is an N bit number shifted
+/// left by S.
+template<unsigned N, unsigned S>
+inline bool isShiftedUInt(uint64_t x) {
+ return isUInt<N+S>(x) && (x % (1<<S) == 0);
+}
+
+/// isUIntN - Checks if an unsigned integer fits into the given (dynamic)
+/// bit width.
+inline bool isUIntN(unsigned N, uint64_t x) {
+ return x == (x & (~0ULL >> (64 - N)));
+}
+
+/// isIntN - Checks if an signed integer fits into the given (dynamic)
+/// bit width.
+inline bool isIntN(unsigned N, int64_t x) {
+ return N >= 64 || (-(INT64_C(1)<<(N-1)) <= x && x < (INT64_C(1)<<(N-1)));
+}
+
+/// isMask_32 - This function returns true if the argument is a sequence of ones
+/// starting at the least significant bit with the remainder zero (32 bit
+/// version). Ex. isMask_32(0x0000FFFFU) == true.
+inline bool isMask_32(uint32_t Value) {
+ return Value && ((Value + 1) & Value) == 0;
+}
+
+/// isMask_64 - This function returns true if the argument is a sequence of ones
+/// starting at the least significant bit with the remainder zero (64 bit
+/// version).
+inline bool isMask_64(uint64_t Value) {
+ return Value && ((Value + 1) & Value) == 0;
+}
+
+/// isShiftedMask_32 - This function returns true if the argument contains a
+/// sequence of ones with the remainder zero (32 bit version.)
+/// Ex. isShiftedMask_32(0x0000FF00U) == true.
+inline bool isShiftedMask_32(uint32_t Value) {
+ return isMask_32((Value - 1) | Value);
+}
+
+/// isShiftedMask_64 - This function returns true if the argument contains a
+/// sequence of ones with the remainder zero (64 bit version.)
+inline bool isShiftedMask_64(uint64_t Value) {
+ return isMask_64((Value - 1) | Value);
+}
+
+/// isPowerOf2_32 - This function returns true if the argument is a power of
+/// two > 0. Ex. isPowerOf2_32(0x00100000U) == true (32 bit edition.)
+inline bool isPowerOf2_32(uint32_t Value) {
+ return Value && !(Value & (Value - 1));
+}
+
+/// isPowerOf2_64 - This function returns true if the argument is a power of two
+/// > 0 (64 bit edition.)
+inline bool isPowerOf2_64(uint64_t Value) {
+ return Value && !(Value & (Value - int64_t(1L)));
+}
+
+/// ByteSwap_16 - This function returns a byte-swapped representation of the
+/// 16-bit argument, Value.
+inline uint16_t ByteSwap_16(uint16_t Value) {
+ return sys::SwapByteOrder_16(Value);
+}
+
+/// ByteSwap_32 - This function returns a byte-swapped representation of the
+/// 32-bit argument, Value.
+inline uint32_t ByteSwap_32(uint32_t Value) {
+ return sys::SwapByteOrder_32(Value);
+}
+
+/// ByteSwap_64 - This function returns a byte-swapped representation of the
+/// 64-bit argument, Value.
+inline uint64_t ByteSwap_64(uint64_t Value) {
+ return sys::SwapByteOrder_64(Value);
+}
+
+/// CountLeadingOnes_32 - this function performs the operation of
+/// counting the number of ones from the most significant bit to the first zero
+/// bit. Ex. CountLeadingOnes_32(0xFF0FFF00) == 8.
+/// Returns 32 if the word is all ones.
+inline unsigned CountLeadingOnes_32(uint32_t Value) {
+ return countLeadingZeros(~Value);
+}
+
+/// CountLeadingOnes_64 - This function performs the operation
+/// of counting the number of ones from the most significant bit to the first
+/// zero bit (64 bit edition.)
+/// Returns 64 if the word is all ones.
+inline unsigned CountLeadingOnes_64(uint64_t Value) {
+ return countLeadingZeros(~Value);
+}
+
+/// CountTrailingOnes_32 - this function performs the operation of
+/// counting the number of ones from the least significant bit to the first zero
+/// bit. Ex. CountTrailingOnes_32(0x00FF00FF) == 8.
+/// Returns 32 if the word is all ones.
+inline unsigned CountTrailingOnes_32(uint32_t Value) {
+ return countTrailingZeros(~Value);
+}
+
+/// CountTrailingOnes_64 - This function performs the operation
+/// of counting the number of ones from the least significant bit to the first
+/// zero bit (64 bit edition.)
+/// Returns 64 if the word is all ones.
+inline unsigned CountTrailingOnes_64(uint64_t Value) {
+ return countTrailingZeros(~Value);
+}
+
+/// CountPopulation_32 - this function counts the number of set bits in a value.
+/// Ex. CountPopulation(0xF000F000) = 8
+/// Returns 0 if the word is zero.
+inline unsigned CountPopulation_32(uint32_t Value) {
+#if __GNUC__ >= 4
+ return __builtin_popcount(Value);
+#else
+ uint32_t v = Value - ((Value >> 1) & 0x55555555);
+ v = (v & 0x33333333) + ((v >> 2) & 0x33333333);
+ return ((v + (v >> 4) & 0xF0F0F0F) * 0x1010101) >> 24;
+#endif
+}