diff options
author | Abseil Team <absl-team@google.com> | 2020-09-18 15:55:15 -0700 |
---|---|---|
committer | Derek Mauro <dmauro@google.com> | 2020-09-24 13:47:15 -0400 |
commit | b56cbdd23834a65682c0b46f367f8679e83bc894 (patch) | |
tree | dacab9a64dd1a9e9668737e511d1a5420ff96001 /absl/numeric/int128.cc | |
parent | b832dce8489ef7b6231384909fd9b68d5a5ff2b7 (diff) |
Abseil LTS 2020092320200923
What's New:
* `absl::StatusOr<T>` has been released. See our [blog
post](https://abseil.io/blog/2020-091021-status) for more
information.
* Abseil Flags reflection interfaces have been released.
* Abseil Flags memory usage has been significantly optimized.
* Abseil now supports a "hardened" build mode. This build mode enables
runtime checks that guard against programming errors that may lead
to security vulnerabilities.
Notable Fixes:
* Sanitizer dynamic annotations like `AnnotateRWLockCreate` that are
also defined by the compiler sanitizer implementation are no longer
also defined by Abseil.
* Sanitizer macros are now prefixed with `ABSL_` to avoid naming collisions.
* Sanitizer usage is now automatically detected and no longer requires
macros like `ADDRESS_SANITIZER` to be defined on the command line.
Breaking Changes:
* Abseil no longer contains a `dynamic_annotations` library. Users
using a supported build system (Bazel or CMake) are unaffected by
this, but users manually specifying link libraries may get an error
about a missing linker input.
Baseline: 7680a5f8efe32de4753baadbd63e74e59d95bac1
Cherry picks: None
Diffstat (limited to 'absl/numeric/int128.cc')
-rw-r--r-- | absl/numeric/int128.cc | 40 |
1 files changed, 13 insertions, 27 deletions
diff --git a/absl/numeric/int128.cc b/absl/numeric/int128.cc index b605a870..e21e5e9a 100644 --- a/absl/numeric/int128.cc +++ b/absl/numeric/int128.cc @@ -15,6 +15,7 @@ #include "absl/numeric/int128.h" #include <stddef.h> + #include <cassert> #include <iomanip> #include <ostream> // NOLINT(readability/streams) @@ -22,6 +23,9 @@ #include <string> #include <type_traits> +#include "absl/base/internal/bits.h" +#include "absl/base/optimization.h" + namespace absl { ABSL_NAMESPACE_BEGIN @@ -31,44 +35,26 @@ ABSL_DLL const uint128 kuint128max = MakeUint128( 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 - base_internal::CountLeadingZeros64(hi); } - return Fls64(Uint128Low64(n)); + const uint64_t low = Uint128Low64(n); + ABSL_INTERNAL_ASSUME(low != 0); + return 63 - base_internal::CountLeadingZeros64(low); } // Long division/modulo for uint128 implemented using the shift-subtract // division algorithm adapted from: // https://stackoverflow.com/questions/5386377/division-without-using -void DivModImpl(uint128 dividend, uint128 divisor, uint128* quotient_ret, - uint128* remainder_ret) { +inline void DivModImpl(uint128 dividend, uint128 divisor, uint128* quotient_ret, + uint128* remainder_ret) { assert(divisor != 0); if (divisor > dividend) { |