diff options
| -rw-r--r-- | absl/numeric/int128.h | 13 |
1 files changed, 10 insertions, 3 deletions
diff --git a/absl/numeric/int128.h b/absl/numeric/int128.h index 2eded2f3b549..803f0ff23ab8 100644 --- a/absl/numeric/int128.h +++ b/absl/numeric/int128.h @@ -45,8 +45,8 @@ namespace absl { // as closely as is practical, including exhibiting undefined behavior in // analogous cases (e.g. division by zero). This type is intended to be a // drop-in replacement once C++ supports an intrinsic `uint128_t` type; when -// that occurs, existing uses of `uint128` will continue to work using that new -// type. +// that occurs, existing well-behaved uses of `uint128` will continue to work +// using that new type. // // Note: code written with this type will continue to compile once `uint128_t` // is introduced, provided the replacement helper functions @@ -70,6 +70,9 @@ namespace absl { // types. // * Conversion to integral types requires an explicit static_cast() to // mimic use of the `-Wnarrowing` compiler flag. +// * The alignment requirement of `uint128` may differ from that of an +// intrinsic 128-bit integer type depending on platform and build +// configuration. // // Example: // @@ -80,7 +83,11 @@ namespace absl { // absl::uint64_t i = v; // Error // absl::uint64_t i = static_cast<uint64_t>(v); // OK // -class alignas(16) uint128 { +class +#if defined(ABSL_HAVE_INTRINSIC_INT128) + alignas(unsigned __int128) +#endif // ABSL_HAVE_INTRINSIC_INT128 + uint128 { public: uint128() = default; |