From ec5096f48bbd7db83cbe94bdd3235c5808a5979a Mon Sep 17 00:00:00 2001 From: Jonathan Wakely Date: Mon, 7 Sep 2020 20:09:17 +0100 Subject: [PATCH] libstdc++: Simplify chrono::duration::_S_gcd We can simplify this constexpr function further because we know that period::num >= 1 and period::den >= 1 so only the remainder can ever be zero. libstdc++-v3/ChangeLog: * include/std/chrono (duration::_S_gcd): Use invariant that neither value is zero initially. --- libstdc++-v3/include/std/chrono | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/libstdc++-v3/include/std/chrono b/libstdc++-v3/include/std/chrono index 0e2efb2522b..afee7859c6d 100644 --- a/libstdc++-v3/include/std/chrono +++ b/libstdc++-v3/include/std/chrono @@ -430,17 +430,18 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION // Duration only allows positive periods so we don't need to // handle negative values here (unlike __static_gcd and std::gcd). #if __cplusplus >= 201402L - while (__m != 0 && __n != 0) + do { intmax_t __rem = __m % __n; __m = __n; __n = __rem; } - return __m + __n; + while (__n != 0); + return __m; #else // C++11 doesn't allow loops in constexpr functions, but this // recursive version can be more expensive to evaluate. - return (__m == 0) ? __n : (__n == 0) ? __m : _S_gcd(__n, __m % __n); + return (__n == 0) ? __m : _S_gcd(__n, __m % __n); #endif }