23 Commits

Author SHA1 Message Date
Arthur O'Dwyer
928852f156 [libc++] [NFC] Remove an unused parameter from __sift_down.
Differential Revision: https://reviews.llvm.org/D116382
2021-12-29 16:25:33 -05:00
Arthur O'Dwyer
b07b5bd727 [libc++] Test that our algorithms never copy a user-provided comparator.
This is not mandated by the standard, so it goes in libcxx/test/libcxx/.
It's certainly arguable that the algorithms changed here
(`is_heap`, `is_sorted`, `min`, `max`) are harmless and we should
just let them copy their comparators once. But at the same time,
it's nice to have all our algorithms be 100% consistent and never
copy a comparator, not even once.

Differential Revision: https://reviews.llvm.org/D114136
2021-11-19 15:03:24 -05:00
Fabian Wolff
dc1c27149f [libc++] Cast to the right difference_type in various algorithms
Differential Revision: https://reviews.llvm.org/D113868
2021-11-18 17:07:36 -05:00
Arthur O'Dwyer
1ce516d43f [libc++] Minor fixups in the new introsort code.
Differential Revision: https://reviews.llvm.org/D114133
2021-11-18 11:01:41 -05:00
Danila Kutenin
a45d2287ad [libc++] Unspecified behavior randomization in libc++
This effort is dedicated to deflake the tests of the users which depend
on the unspecified behavior of algorithms and containers. This also
might help updating the sorting algorithm in libcxx which has the
quadratic worst case in the future or at least create a new one under
flag.

For detailed design, please see the design doc I provide in the patch.

Differential Revision: https://reviews.llvm.org/D96946
2021-11-16 15:55:33 -05:00
Nilay Vaish
7f287390d7 [libc++] Add introsort to avoid O(n^2) behavior
This commit adds a benchmark that tests std::sort on an adversarial inputs,
and uses introsort in std::sort to avoid O(n^2) behavior on adversarial
inputs.

Inputs where partitions are unbalanced even after 2 log(n) pivots have
been selected, the algorithm switches to heap sort to avoid the
possibility of spending O(n^2) time on sorting the input.
Benchmark results show that the intro sort implementation does
significantly better.

Benchmarking results before this change. Time represents the sorting
time required per element:

----------------------------------------------------------------------------------------------------------
Benchmark                                                                Time             CPU   Iterations
----------------------------------------------------------------------------------------------------------
BM_Sort_uint32_QuickSortAdversary_1                                   3.75 ns         3.74 ns    187432960
BM_Sort_uint32_QuickSortAdversary_4                                   3.05 ns         3.05 ns    231211008
BM_Sort_uint32_QuickSortAdversary_16                                  2.45 ns         2.45 ns    288096256
BM_Sort_uint32_QuickSortAdversary_64                                  32.8 ns         32.8 ns     21495808
BM_Sort_uint32_QuickSortAdversary_256                                  132 ns          132 ns      5505024
BM_Sort_uint32_QuickSortAdversary_1024                                 498 ns          497 ns      1572864
BM_Sort_uint32_QuickSortAdversary_16384                               3846 ns         3845 ns       262144
BM_Sort_uint32_QuickSortAdversary_262144                             61431 ns        61400 ns       262144
BM_Sort_uint64_QuickSortAdversary_1                                   3.93 ns         3.92 ns    181141504
BM_Sort_uint64_QuickSortAdversary_4                                   3.10 ns         3.09 ns    222560256
BM_Sort_uint64_QuickSortAdversary_16                                  2.50 ns         2.50 ns    283639808
BM_Sort_uint64_QuickSortAdversary_64                                  33.2 ns         33.2 ns     21757952
BM_Sort_uint64_QuickSortAdversary_256                                  132 ns          132 ns      5505024
BM_Sort_uint64_QuickSortAdversary_1024                                 478 ns          477 ns      1572864
BM_Sort_uint64_QuickSortAdversary_16384                               3932 ns         3930 ns       262144
BM_Sort_uint64_QuickSortAdversary_262144                             61646 ns        61615 ns       262144

Benchmarking results after this change:

----------------------------------------------------------------------------------------------------------
Benchmark                                                                Time             CPU   Iterations
----------------------------------------------------------------------------------------------------------
BM_Sort_uint32_QuickSortAdversary_1                                   6.31 ns         6.30 ns    107741184
BM_Sort_uint32_QuickSortAdversary_4                                   4.51 ns         4.50 ns    158859264
BM_Sort_uint32_QuickSortAdversary_16                                  3.00 ns         3.00 ns    223608832
BM_Sort_uint32_QuickSortAdversary_64                                  44.8 ns         44.8 ns     15990784
BM_Sort_uint32_QuickSortAdversary_256                                 69.0 ns         68.9 ns      9961472
BM_Sort_uint32_QuickSortAdversary_1024                                 118 ns          118 ns      6029312
BM_Sort_uint32_QuickSortAdversary_16384                                175 ns          175 ns      4194304
BM_Sort_uint32_QuickSortAdversary_262144                               210 ns          210 ns      3407872
BM_Sort_uint64_QuickSortAdversary_1                                   6.75 ns         6.73 ns    103809024
BM_Sort_uint64_QuickSortAdversary_4                                   4.53 ns         4.53 ns    160432128
BM_Sort_uint64_QuickSortAdversary_16                                  2.98 ns         2.97 ns    234356736
BM_Sort_uint64_QuickSortAdversary_64                                  44.3 ns         44.3 ns     15990784
BM_Sort_uint64_QuickSortAdversary_256                                 69.2 ns         69.2 ns     10223616
BM_Sort_uint64_QuickSortAdversary_1024                                 119 ns          119 ns      6029312
BM_Sort_uint64_QuickSortAdversary_16384                                173 ns          173 ns      4194304
BM_Sort_uint64_QuickSortAdversary_262144                               212 ns          212 ns      3407872

Differential Revision: https://reviews.llvm.org/D113413
2021-11-16 11:38:46 -05:00
Louis Dionne
855a419b92 [libc++] Add missing _LIBCPP_HIDE_FROM_ABI to __rewrap_iter 2021-11-15 10:10:33 -05:00
Louis Dionne
f4c1258d56 [libc++] Add an option to disable wide character support in libc++
Some embedded platforms do not wish to support the C library functionality
for handling wchar_t because they have no use for it. It makes sense for
libc++ to work properly on those platforms, so this commit adds a carve-out
of functionality for wchar_t.

Unfortunately, unlike some other carve-outs (e.g. random device), this
patch touches several parts of the library. However, despite the wide
impact of this patch, I still think it is important to support this
configuration since it makes it much simpler to port libc++ to some
embedded platforms.

Differential Revision: https://reviews.llvm.org/D111265
2021-10-12 06:08:23 -04:00
Arthur O'Dwyer
16bf43398a [libc++] Comma-operator-proof a lot of algorithm/container code.
Detected by evil-izing the widely used `MoveOnly` testing type.
I had to patch some tests that were themselves using its comma operator,
but I think that's a worthwhile cost in order to catch more places
in our headers that needed comma-proofing.

The trick here is that even `++ptr, SomeClass()` can find a comma operator
by ADL, if `ptr` is of type `Evil*`. (A comma between two operands
of non-class-or-enum type is always treated as the built-in
comma, without ADL. But if either operand is class-or-enum, then
ADL happens for _both_ operands' types.)

Differential Revision: https://reviews.llvm.org/D109414
2021-09-08 13:34:01 -04:00
Louis Dionne
64184b4af0 [libc++][NFC] Remove useless _LIBCPP_PUSH_MACROS
Only files that actually use min/max are required to do this dance.

Differential Revision: https://reviews.llvm.org/D108778
2021-08-27 12:41:55 -04:00
Arthur O'Dwyer
ca7926bd79 [libc++] Eliminate needless add_lvalue_reference from <algorithm> helpers. NFCI.
When `_Compare` is a function parameter already (so it's not `void`
and it's not an abominable function type), `add_lvalue_reference_t<_Compare>`
is simply a synonym for `_Compare&`. We don't need to pull in `<type_traits>`
and instantiate a template trait to figure that out.

Differential Revision: https://reviews.llvm.org/D108400
2021-08-22 11:43:12 -04:00
Joe Loser
9807626bc7 [libc++] Include <__iterator/distance.h> instead of <iterator> in a few algorithm headers
A few headers in algorithm include `<iterator>` when
`<__iterator/distance.h>` would suffice. Change them
to just include `<__iterator.distance.h>`.

Differential Revision: https://reviews.llvm.org/D108393
2021-08-20 15:02:33 -04:00
Arthur O'Dwyer
f221d905b1 [libc++] IWYU to fix Modules complaints about _LIBCPP_ASSERT. NFCI.
This fixes all places that used _LIBCPP_ASSERT without including <__debug>.

    git grep -l _LIBCPP_ASSERT | xargs git grep -L __debug
2021-08-06 09:20:59 -04:00
Louis Dionne
d03aa7d6b6 [libc++] NFCI: Remove __functional/search.h
The __search helper function was once split into __functional for circular
dependency reasons, however this is not an issue anymore now that we have
finer grained headers.
2021-06-29 11:40:47 -04:00
Louis Dionne
7756216547 [libc++] NFCI: Remove code duplication and obsolete declarations in wrap_iter
Differential Revision: https://reviews.llvm.org/D105040
2021-06-29 10:51:07 -04:00
Christopher Di Bella
6adbc83ee9 [libcxx][modularisation] moves <utility> content out of <type_traits>
Moves:

* `std::move`, `std::forward`, `std::declval`, and `std::swap` into
  `__utility/${FUNCTION_NAME}`.
* `std::swap_ranges` and `std::iter_swap` into
  `__algorithm/${FUNCTION_NAME}`

Differential Revision: https://reviews.llvm.org/D103734
2021-06-24 17:57:29 +00:00
Louis Dionne
134723edd5 [libcxx] Move all algorithms into their own headers
This is a fairly mechanical change, it just moves each algorithm into
its own header. This is intended to be a NFC.

This commit re-applies 7ed7d4ccb899, which was reverted in 692d7166f771
because the Modules build got broken. The modules build has now been
fixed, so we're re-committing this.

Differential Revision: https://reviews.llvm.org/D103583

Attribution note
----------------
I'm only committing this. This commit is a mix of D103583, D103330 and
D104171 authored by:

Co-authored-by: Christopher Di Bella <cjdb@google.com>
Co-authored-by: zoecarver <z.zoelec2@gmail.com>
2021-06-19 07:49:06 -04:00
Petr Hosek
692d7166f7 Revert "[libcxx][gardening] Move all algorithms into their own headers."
This reverts commit 7ed7d4ccb8991e2b5b95334b508f8cec2faee737 as it
uncovered a Clang bug PR50592.
2021-06-07 17:15:20 -07:00
zoecarver
7ed7d4ccb8 [libcxx][gardening] Move all algorithms into their own headers.
This is a fairly mechanical change, it just moves each algorithm into its own header. This is a NFC.

Note: during this change, I burned down all the includes, so this follows "include only and exactly what you use."

Differential Revision: https://reviews.llvm.org/D103583
2021-06-04 09:37:12 -07:00
Louis Dionne
05d164b25c Revert "[libc++] NFC: Move unwrap_iter to its own header"
This reverts commit 924ea3bb53 *again*, this time because it broke the
LLDB build with modules. We need to figure out what's up with the libc++
modules build once and for all.

Differential Revision: https://reviews.llvm.org/D103369
2021-06-02 15:58:27 -04:00
Louis Dionne
924ea3bb53 [libc++] NFC: Move unwrap_iter to its own header
This re-applies 9968896cd62a, which was reverted in b13edf6e907b because
it broke the build.

Differential Revision: https://reviews.llvm.org/D103369
2021-06-01 21:46:59 -04:00
Mark de Wever
b13edf6e90 Revert "[libc++] NFC: Move unwrap_iter to its own header"
This reverts commit 9968896cd62a62b11ac61085534dd598c4bd3c60.

This commit seems to cause the build failures of main.
2021-05-29 09:50:26 +02:00
Louis Dionne
9968896cd6 [libc++] NFC: Move unwrap_iter to its own header 2021-05-28 12:42:07 -04:00