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author | 2021-08-19 13:34:28 -0700 | |
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committer | 2021-08-19 22:49:58 -0400 | |
commit | a05366d851c5cb88065272f951e03955197e7c11 (patch) | |
tree | 70b87b4feb75fc1464d2deae56da62128ce6d813 /absl/numeric/int128_no_intrinsic.inc | |
parent | 189d55a57f57731d335fd84999d5dccf771b8e6b (diff) |
Export of internal Abseil changes
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04cb3b22497190170aa5b774e98080c5de2ba60b by Abseil Team <absl-team@google.com>:
Alternative bit mixer for LowLevelHash on ARM
LowLevelHash's bit-mixer is inefficient on ARM because it calculates a 128-bit product of two 64-bit numbers. On ARM, this requires a sequence of two instructions with a high combined latency and poor throughput. This change provides alternative bit-mixing code for ARM that uses only 64-bit arithmetic (multiplication, xor, and left-shifts) and speeds things up considerably.
The bit-mixing code for ARM was inspired by by Woothash[1] and xxh3[1]. Once I landed on a sequence of operations that provided good mixing, I used a test harness to search for the combination of shift / rotate factors that provided the best mixing, as indicated by SMHasher hash quality tests. The new mixing code passes 13 out of 15 of the hash quality test suites in SMHasher, with the two failures being in the noise range: e.g. 1 collision vs. zero expected in a keyset of ~8m keys.
[1]: https://github.com/tommyettinger/waterhash/blob/49f5cf0b63b9/woothash.h#L16-L20
[2]: https://github.com/Cyan4973/xxHash/blob/6853ddc36e46/xxhash.h#L3240-L3265
PiperOrigin-RevId: 391833008
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17a4de1f9d623155c75b19285d414cd55a487cd6 by Saleem Abdulrasool <abdulras@google.com>:
debugging: add support for unwinding on RISCV Linux
This adds partial support for unwinding the RISCV call stack. It is largely
duplicated from the AArch64 support with alterations for the ELF RISCV psABI.
This covers RISCV64 and RISCV32, though not the ILP32E calling convention.
PiperOrigin-RevId: 391818522
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32c93e449327b2cea32b32f6365e84b420fe1ed3 by Gennadiy Rozental <rogeeff@google.com>:
New storage for types smaller than 8 bytes.
Also adding new read interface for types smaller than or rqual to 8 bytes to avoid passing the pointer.
PiperOrigin-RevId: 391726822
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e987ac08a7787801cbfc7d7c96649e97fa8cff1a by Abseil Team <absl-team@google.com>:
Extern template `find_first_non_full` to reduce linkage size for TU with single not inlined function.
PiperOrigin-RevId: 391718862
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73af9bfcb5bf045089133e18bbd20eb5bb699172 by Gennadiy Rozental <rogeeff@google.com>:
Make most non-mutable most int128 methods and friend free functions constexpr.
Some functions are implemented offline (at least in some configurations) and can't be made constexpr. Mutable methods can't be made constexpr until we drop c++11 support.
Fixes #978
PiperOrigin-RevId: 391706535
GitOrigin-RevId: 04cb3b22497190170aa5b774e98080c5de2ba60b
Change-Id: If051fad5ff004e2e82fa53618fc04a6fe3d2d4be
Diffstat (limited to 'absl/numeric/int128_no_intrinsic.inc')
-rw-r--r-- | absl/numeric/int128_no_intrinsic.inc | 133 |
1 files changed, 65 insertions, 68 deletions
diff --git a/absl/numeric/int128_no_intrinsic.inc b/absl/numeric/int128_no_intrinsic.inc index c753771a..66f6809f 100644 --- a/absl/numeric/int128_no_intrinsic.inc +++ b/absl/numeric/int128_no_intrinsic.inc @@ -134,10 +134,6 @@ constexpr int128::operator unsigned long long() const { // NOLINT(runtime/int) return static_cast<unsigned long long>(lo_); // NOLINT(runtime/int) } -// Forward declaration for conversion operators to floating point types. -int128 operator-(int128 v); -bool operator!=(int128 lhs, int128 rhs); - inline int128::operator float() const { // We must convert the absolute value and then negate as needed, because // floating point types are typically sign-magnitude. Otherwise, the @@ -169,76 +165,80 @@ inline int128::operator long double() const { // Comparison operators. -inline bool operator==(int128 lhs, int128 rhs) { +constexpr bool operator==(int128 lhs, int128 rhs) { return (Int128Low64(lhs) == Int128Low64(rhs) && Int128High64(lhs) == Int128High64(rhs)); } -inline bool operator!=(int128 lhs, int128 rhs) { - return !(lhs == rhs); -} +constexpr bool operator!=(int128 lhs, int128 rhs) { return !(lhs == rhs); } -inline bool operator<(int128 lhs, int128 rhs) { +constexpr bool operator<(int128 lhs, int128 rhs) { return (Int128High64(lhs) == Int128High64(rhs)) ? (Int128Low64(lhs) < Int128Low64(rhs)) : (Int128High64(lhs) < Int128High64(rhs)); } -inline bool operator>(int128 lhs, int128 rhs) { +constexpr bool operator>(int128 lhs, int128 rhs) { return (Int128High64(lhs) == Int128High64(rhs)) ? (Int128Low64(lhs) > Int128Low64(rhs)) : (Int128High64(lhs) > Int128High64(rhs)); } -inline bool operator<=(int128 lhs, int128 rhs) { - return !(lhs > rhs); -} +constexpr bool operator<=(int128 lhs, int128 rhs) { return !(lhs > rhs); } -inline bool operator>=(int128 lhs, int128 rhs) { - return !(lhs < rhs); -} +constexpr bool operator>=(int128 lhs, int128 rhs) { return !(lhs < rhs); } // Unary operators. -inline int128 operator-(int128 v) { - int64_t hi = ~Int128High64(v); - uint64_t lo = ~Int128Low64(v) + 1; - if (lo == 0) ++hi; // carry - return MakeInt128(hi, lo); +constexpr int128 operator-(int128 v) { + return MakeInt128(~Int128High64(v) + (Int128Low64(v) == 0), + ~Int128Low64(v) + 1); } -inline bool operator!(int128 v) { +constexpr bool operator!(int128 v) { return !Int128Low64(v) && !Int128High64(v); } -inline int128 operator~(int128 val) { +constexpr int128 operator~(int128 val) { return MakeInt128(~Int128High64(val), ~Int128Low64(val)); } // Arithmetic operators. -inline int128 operator+(int128 lhs, int128 rhs) { - int128 result = MakeInt128(Int128High64(lhs) + Int128High64(rhs), - Int128Low64(lhs) + Int128Low64(rhs)); - if (Int128Low64(result) < Int128Low64(lhs)) { // check for carry - return MakeInt128(Int128High64(result) + 1, Int128Low64(result)); - } - return result; +namespace int128_internal { +constexpr int128 SignedAddResult(int128 result, int128 lhs) { + // check for carry + return (Int128Low64(result) < Int128Low64(lhs)) + ? MakeInt128(Int128High64(result) + 1, Int128Low64(result)) + : result; +} +} // namespace int128_internal +constexpr int128 operator+(int128 lhs, int128 rhs) { + return int128_internal::SignedAddResult( + MakeInt128(Int128High64(lhs) + Int128High64(rhs), + Int128Low64(lhs) + Int128Low64(rhs)), + lhs); } -inline int128 operator-(int128 lhs, int128 rhs) { - int128 result = MakeInt128(Int128High64(lhs) - Int128High64(rhs), - Int128Low64(lhs) - Int128Low64(rhs)); - if (Int128Low64(lhs) < Int128Low64(rhs)) { // check for carry - return MakeInt128(Int128High64(result) - 1, Int128Low64(result)); - } - return result; +namespace int128_internal { +constexpr int128 SignedSubstructResult(int128 result, int128 lhs, int128 rhs) { + // check for carry + return (Int128Low64(lhs) < Int128Low64(rhs)) + ? MakeInt128(Int128High64(result) - 1, Int128Low64(result)) + : result; +} +} // namespace int128_internal +constexpr int128 operator-(int128 lhs, int128 rhs) { + return int128_internal::SignedSubstructResult( + MakeInt128(Int128High64(lhs) - Int128High64(rhs), + Int128Low64(lhs) - Int128Low64(rhs)), + lhs, rhs); } inline int128 operator*(int128 lhs, int128 rhs) { - uint128 result = uint128(lhs) * rhs; - return MakeInt128(int128_internal::BitCastToSigned(Uint128High64(result)), - Uint128Low64(result)); + return MakeInt128( + int128_internal::BitCastToSigned(Uint128High64(uint128(lhs) * rhs)), + Uint128Low64(uint128(lhs) * rhs)); } inline int128 int128::operator++(int) { @@ -263,46 +263,43 @@ inline int128& int128::operator--() { return *this; } -inline int128 operator|(int128 lhs, int128 rhs) { +constexpr int128 operator|(int128 lhs, int128 rhs) { return MakeInt128(Int128High64(lhs) | Int128High64(rhs), Int128Low64(lhs) | Int128Low64(rhs)); } -inline int128 operator&(int128 lhs, int128 rhs) { +constexpr int128 operator&(int128 lhs, int128 rhs) { return MakeInt128(Int128High64(lhs) & Int128High64(rhs), Int128Low64(lhs) & Int128Low64(rhs)); } -inline int128 operator^(int128 lhs, int128 rhs) { +constexpr int128 operator^(int128 lhs, int128 rhs) { return MakeInt128(Int128High64(lhs) ^ Int128High64(rhs), Int128Low64(lhs) ^ Int128Low64(rhs)); } -inline int128 operator<<(int128 lhs, int amount) { +constexpr int128 operator<<(int128 lhs, int amount) { // uint64_t shifts of >= 64 are undefined, so we need some special-casing. - if (amount < 64) { - if (amount != 0) { - return MakeInt128( - (Int128High64(lhs) << amount) | - static_cast<int64_t>(Int128Low64(lhs) >> (64 - amount)), - Int128Low64(lhs) << amount); - } - return lhs; - } - return MakeInt128(static_cast<int64_t>(Int128Low64(lhs) << (amount - 64)), 0); -} - -inline int128 operator>>(int128 lhs, int amount) { + return amount >= 64 + ? MakeInt128( + static_cast<int64_t>(Int128Low64(lhs) << (amount - 64)), 0) + : amount == 0 + ? lhs + : MakeInt128( + (Int128High64(lhs) << amount) | + static_cast<int64_t>(Int128Low64(lhs) >> (64 - amount)), + Int128Low64(lhs) << amount); +} + +constexpr int128 operator>>(int128 lhs, int amount) { // uint64_t shifts of >= 64 are undefined, so we need some special-casing. - if (amount < 64) { - if (amount != 0) { - return MakeInt128( - Int128High64(lhs) >> amount, - (Int128Low64(lhs) >> amount) | - (static_cast<uint64_t>(Int128High64(lhs)) << (64 - amount))); - } - return lhs; - } - return MakeInt128(0, - static_cast<uint64_t>(Int128High64(lhs) >> (amount - 64))); + return amount >= 64 + ? MakeInt128( + 0, static_cast<uint64_t>(Int128High64(lhs) >> (amount - 64))) + : amount == 0 + ? lhs + : MakeInt128(Int128High64(lhs) >> amount, + (Int128Low64(lhs) >> amount) | + (static_cast<uint64_t>(Int128High64(lhs)) + << (64 - amount))); } |