Implements parts of P1614R2
Implemented `operator<=>` for `multiset` and `set`
Reviewed By: #libc, Mordante
Differential Revision: https://reviews.llvm.org/D148416
The implementation makes use of the freedom added by LWG 3410. We have
two variants of this algorithm:
* a fast path for random access iterators: This fast path computes the
maximum number of loop iterations up-front and does not compare the
iterators against their limits on every loop iteration.
* A basic implementation for all other iterators: This implementation
compares the iterators against their limits in every loop iteration.
However, it still takes advantage of the freedom added by LWG 3410 to
avoid unnecessary additional iterator comparisons, as originally
specified by P1614R2.
https://godbolt.org/z/7xbMEen5e shows the benefit of the fast path:
The hot loop generated of `lexicographical_compare_three_way3` is
more tight than for `lexicographical_compare_three_way1`. The added
benchmark illustrates how this leads to a 30% - 50% performance
improvement on integer vectors.
Implements part of P1614R2 "The Mothership has Landed"
Fixes LWG 3410 and LWG 3350
Differential Revision: https://reviews.llvm.org/D131395
I accidentally wrote `testComparisons(...)` instead of
`assert(testComparisons(...))`. This compiled without issues, but
did not provide the intended test coverage. By adding a `nodiscard`,
we can make sure that the compiler catches such mistakes for us.
Differential Revision: https://reviews.llvm.org/D131364
In D130295 @mumbleskates wondered why `std::strong_ordering::equal` had
special code since it's the same as `std::strong_ordering::equivalent`.
This is indeed the case so the special case can be removed.
Reviewed By: mumbleskates, #libc, avogelsgesang, ldionne
Differential Revision: https://reviews.llvm.org/D131419
to reflect the new license. These used slightly different spellings that
defeated my regular expressions.
We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.
Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.
llvm-svn: 351648
