3dfd5493cf
This patch reimplements std::chrono::year_month_day::_S_from_days() which retrieves a date from the number of elapsed days since 1970/01/01. The new implementation is based on Proposition 6.3 of Neri and Schneider, "Euclidean Affine Functions and Applications to Calendar Algorithms" available at https://arxiv.org/abs/2102.06959. The aforementioned paper benchmarks the implementation against several counterparts, including libc++'s (which is identical to the current implementation). The results, shown in Figure 4, indicate the new algorithm is 2.2 times faster than the current one. The patch adds a test which loops through all integers in [-12687428, 11248737], and for each of them, gets the corresponding date and compares the result against its expected value. The latter is calculated using a much simpler and easy to understand algorithm but which is also much slower. The interval used in the test covers the full range of values for which a roundtrip must work [time.cal.ymd.members]. Despite its completeness the test runs in a matter of seconds. libstdc++-v3/ChangeLog: * include/std/chrono (year_month_day::_S_from_days): New implementation. * testsuite/std/time/year_month_day/3.cc: New test. |
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| ChangeLog | ||
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| config.h.in | ||
| configure | ||
| configure.ac | ||
| configure.host | ||
| crossconfig.m4 | ||
| fragment.am | ||
| linkage.m4 | ||
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| README | ||
file: libstdc++-v3/README New users may wish to point their web browsers to the file index.html in the 'doc/html' subdirectory. It contains brief building instructions and notes on how to configure the library in interesting ways.