diff options
Diffstat (limited to 'src/third_party/abseil-cpp-master/abseil-cpp/absl/numeric/int128.cc')
| -rw-r--r-- | src/third_party/abseil-cpp-master/abseil-cpp/absl/numeric/int128.cc | 201 |
1 files changed, 170 insertions, 31 deletions
diff --git a/src/third_party/abseil-cpp-master/abseil-cpp/absl/numeric/int128.cc b/src/third_party/abseil-cpp-master/abseil-cpp/absl/numeric/int128.cc index 3c37f252a79..5160df793ea 100644 --- a/src/third_party/abseil-cpp-master/abseil-cpp/absl/numeric/int128.cc +++ b/src/third_party/abseil-cpp-master/abseil-cpp/absl/numeric/int128.cc @@ -4,7 +4,7 @@ // 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 +// https://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, @@ -15,6 +15,7 @@ #include "absl/numeric/int128.h" #include <stddef.h> + #include <cassert> #include <iomanip> #include <ostream> // NOLINT(readability/streams) @@ -22,52 +23,38 @@ #include <string> #include <type_traits> +#include "absl/base/optimization.h" +#include "absl/numeric/bits.h" + namespace absl { +ABSL_NAMESPACE_BEGIN -const uint128 kuint128max = MakeUint128(std::numeric_limits<uint64_t>::max(), - std::numeric_limits<uint64_t>::max()); +ABSL_DLL const uint128 kuint128max = MakeUint128( + std::numeric_limits<uint64_t>::max(), std::numeric_limits<uint64_t>::max()); namespace { // Returns the 0-based position of the last set bit (i.e., most significant bit) -// in the given uint64_t. The argument may not be 0. +// in the given uint128. The argument is not 0. // // For example: // Given: 5 (decimal) == 101 (binary) // Returns: 2 -#define STEP(T, n, pos, sh) \ - do { \ - if ((n) >= (static_cast<T>(1) << (sh))) { \ - (n) = (n) >> (sh); \ - (pos) |= (sh); \ - } \ - } while (0) -static inline int Fls64(uint64_t n) { - assert(n != 0); - int pos = 0; - STEP(uint64_t, n, pos, 0x20); - uint32_t n32 = static_cast<uint32_t>(n); - STEP(uint32_t, n32, pos, 0x10); - STEP(uint32_t, n32, pos, 0x08); - STEP(uint32_t, n32, pos, 0x04); - return pos + ((uint64_t{0x3333333322221100} >> (n32 << 2)) & 0x3); -} -#undef STEP - -// Like Fls64() above, but returns the 0-based position of the last set bit -// (i.e., most significant bit) in the given uint128. The argument may not be 0. -static inline int Fls128(uint128 n) { +inline ABSL_ATTRIBUTE_ALWAYS_INLINE int Fls128(uint128 n) { if (uint64_t hi = Uint128High64(n)) { - return Fls64(hi) + 64; + ABSL_INTERNAL_ASSUME(hi != 0); + return 127 - countl_zero(hi); } - return Fls64(Uint128Low64(n)); + const uint64_t low = Uint128Low64(n); + ABSL_INTERNAL_ASSUME(low != 0); + return 63 - countl_zero(low); } // Long division/modulo for uint128 implemented using the shift-subtract // division algorithm adapted from: -// http://stackoverflow.com/questions/5386377/division-without-using -void DivModImpl(uint128 dividend, uint128 divisor, uint128* quotient_ret, - uint128* remainder_ret) { +// https://stackoverflow.com/questions/5386377/division-without-using +inline void DivModImpl(uint128 dividend, uint128 divisor, uint128* quotient_ret, + uint128* remainder_ret) { assert(divisor != 0); if (divisor > dividend) { @@ -123,6 +110,28 @@ uint128 MakeUint128FromFloat(T v) { return MakeUint128(0, static_cast<uint64_t>(v)); } + +#if defined(__clang__) && !defined(__SSE3__) +// Workaround for clang bug: https://bugs.llvm.org/show_bug.cgi?id=38289 +// Casting from long double to uint64_t is miscompiled and drops bits. +// It is more work, so only use when we need the workaround. +uint128 MakeUint128FromFloat(long double v) { + // Go 50 bits at a time, that fits in a double + static_assert(std::numeric_limits<double>::digits >= 50, ""); + static_assert(std::numeric_limits<long double>::digits <= 150, ""); + // Undefined behavior if v is not finite or cannot fit into uint128. + assert(std::isfinite(v) && v > -1 && v < std::ldexp(1.0L, 128)); + + v = std::ldexp(v, -100); + uint64_t w0 = static_cast<uint64_t>(static_cast<double>(std::trunc(v))); + v = std::ldexp(v - static_cast<double>(w0), 50); + uint64_t w1 = static_cast<uint64_t>(static_cast<double>(std::trunc(v))); + v = std::ldexp(v - static_cast<double>(w1), 50); + uint64_t w2 = static_cast<uint64_t>(static_cast<double>(std::trunc(v))); + return (static_cast<uint128>(w0) << 100) | (static_cast<uint128>(w1) << 50) | + static_cast<uint128>(w2); +} +#endif // __clang__ && !__SSE3__ } // namespace uint128::uint128(float v) : uint128(MakeUint128FromFloat(v)) {} @@ -222,6 +231,112 @@ std::ostream& operator<<(std::ostream& os, uint128 v) { return os << rep; } +namespace { + +uint128 UnsignedAbsoluteValue(int128 v) { + // Cast to uint128 before possibly negating because -Int128Min() is undefined. + return Int128High64(v) < 0 ? -uint128(v) : uint128(v); +} + +} // namespace + +#if !defined(ABSL_HAVE_INTRINSIC_INT128) +namespace { + +template <typename T> +int128 MakeInt128FromFloat(T v) { + // Conversion when v is NaN or cannot fit into int128 would be undefined + // behavior if using an intrinsic 128-bit integer. + assert(std::isfinite(v) && (std::numeric_limits<T>::max_exponent <= 127 || + (v >= -std::ldexp(static_cast<T>(1), 127) && + v < std::ldexp(static_cast<T>(1), 127)))); + + // We must convert the absolute value and then negate as needed, because + // floating point types are typically sign-magnitude. Otherwise, the + // difference between the high and low 64 bits when interpreted as two's + // complement overwhelms the precision of the mantissa. + uint128 result = v < 0 ? -MakeUint128FromFloat(-v) : MakeUint128FromFloat(v); + return MakeInt128(int128_internal::BitCastToSigned(Uint128High64(result)), + Uint128Low64(result)); +} + +} // namespace + +int128::int128(float v) : int128(MakeInt128FromFloat(v)) {} +int128::int128(double v) : int128(MakeInt128FromFloat(v)) {} +int128::int128(long double v) : int128(MakeInt128FromFloat(v)) {} + +int128 operator/(int128 lhs, int128 rhs) { + assert(lhs != Int128Min() || rhs != -1); // UB on two's complement. + + uint128 quotient = 0; + uint128 remainder = 0; + DivModImpl(UnsignedAbsoluteValue(lhs), UnsignedAbsoluteValue(rhs), + "ient, &remainder); + if ((Int128High64(lhs) < 0) != (Int128High64(rhs) < 0)) quotient = -quotient; + return MakeInt128(int128_internal::BitCastToSigned(Uint128High64(quotient)), + Uint128Low64(quotient)); +} + +int128 operator%(int128 lhs, int128 rhs) { + assert(lhs != Int128Min() || rhs != -1); // UB on two's complement. + + uint128 quotient = 0; + uint128 remainder = 0; + DivModImpl(UnsignedAbsoluteValue(lhs), UnsignedAbsoluteValue(rhs), + "ient, &remainder); + if (Int128High64(lhs) < 0) remainder = -remainder; + return MakeInt128(int128_internal::BitCastToSigned(Uint128High64(remainder)), + Uint128Low64(remainder)); +} +#endif // ABSL_HAVE_INTRINSIC_INT128 + +std::ostream& operator<<(std::ostream& os, int128 v) { + std::ios_base::fmtflags flags = os.flags(); + std::string rep; + + // Add the sign if needed. + bool print_as_decimal = + (flags & std::ios::basefield) == std::ios::dec || + (flags & std::ios::basefield) == std::ios_base::fmtflags(); + if (print_as_decimal) { + if (Int128High64(v) < 0) { + rep = "-"; + } else if (flags & std::ios::showpos) { + rep = "+"; + } + } + + rep.append(Uint128ToFormattedString( + print_as_decimal ? UnsignedAbsoluteValue(v) : uint128(v), os.flags())); + + // Add the requisite padding. + std::streamsize width = os.width(0); + if (static_cast<size_t>(width) > rep.size()) { + switch (flags & std::ios::adjustfield) { + case std::ios::left: + rep.append(width - rep.size(), os.fill()); + break; + case std::ios::internal: + if (print_as_decimal && (rep[0] == '+' || rep[0] == '-')) { + rep.insert(1, width - rep.size(), os.fill()); + } else if ((flags & std::ios::basefield) == std::ios::hex && + (flags & std::ios::showbase) && v != 0) { + rep.insert(2, width - rep.size(), os.fill()); + } else { + rep.insert(0, width - rep.size(), os.fill()); + } + break; + default: // std::ios::right + rep.insert(0, width - rep.size(), os.fill()); + break; + } + } + + return os << rep; +} + +ABSL_NAMESPACE_END } // namespace absl namespace std { @@ -248,4 +363,28 @@ constexpr int numeric_limits<absl::uint128>::max_exponent; constexpr int numeric_limits<absl::uint128>::max_exponent10; constexpr bool numeric_limits<absl::uint128>::traps; constexpr bool numeric_limits<absl::uint128>::tinyness_before; + +constexpr bool numeric_limits<absl::int128>::is_specialized; +constexpr bool numeric_limits<absl::int128>::is_signed; +constexpr bool numeric_limits<absl::int128>::is_integer; +constexpr bool numeric_limits<absl::int128>::is_exact; +constexpr bool numeric_limits<absl::int128>::has_infinity; +constexpr bool numeric_limits<absl::int128>::has_quiet_NaN; +constexpr bool numeric_limits<absl::int128>::has_signaling_NaN; +constexpr float_denorm_style numeric_limits<absl::int128>::has_denorm; +constexpr bool numeric_limits<absl::int128>::has_denorm_loss; +constexpr float_round_style numeric_limits<absl::int128>::round_style; +constexpr bool numeric_limits<absl::int128>::is_iec559; +constexpr bool numeric_limits<absl::int128>::is_bounded; +constexpr bool numeric_limits<absl::int128>::is_modulo; +constexpr int numeric_limits<absl::int128>::digits; +constexpr int numeric_limits<absl::int128>::digits10; +constexpr int numeric_limits<absl::int128>::max_digits10; +constexpr int numeric_limits<absl::int128>::radix; +constexpr int numeric_limits<absl::int128>::min_exponent; +constexpr int numeric_limits<absl::int128>::min_exponent10; +constexpr int numeric_limits<absl::int128>::max_exponent; +constexpr int numeric_limits<absl::int128>::max_exponent10; +constexpr bool numeric_limits<absl::int128>::traps; +constexpr bool numeric_limits<absl::int128>::tinyness_before; } // namespace std |