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Update umul128_upper64 to use optimised x64 version of umul128

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Laurent GIORELLO 2023-11-10 03:45:30 +00:00
parent eb6085d99a
commit 1436fc76e9
1 changed files with 3 additions and 1 deletions
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4
include/fmt/format.h
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@ -1535,7 +1535,9 @@ inline int floor_log2_pow10(int e) noexcept {
// Computes upper 64 bits of multiplication of two 64-bit unsigned integers. // Computes upper 64 bits of multiplication of two 64-bit unsigned integers.
inline uint64_t umul128_upper64(uint64_t x, uint64_t y) noexcept { inline uint64_t umul128_upper64(uint64_t x, uint64_t y) noexcept {
#if FMT_USE_INT128 #if __x86_64__ && (__GNUC__ || __clang__)
return umul128(x, y).high();
#elif FMT_USE_INT128
auto p = static_cast<uint128_opt>(x) * static_cast<uint128_opt>(y); auto p = static_cast<uint128_opt>(x) * static_cast<uint128_opt>(y);
return static_cast<uint64_t>(p >> 64); return static_cast<uint64_t>(p >> 64);
#elif defined(_MSC_VER) && defined(_M_X64) #elif defined(_MSC_VER) && defined(_M_X64)