15 Commits

Author SHA1 Message Date
Nikolas Klauser
06c6a5020f
[libc++] Optimize search_n (#171389)
This changes the algorithm to more efficiently skip ranges which cannot
match the needle for random access iterators. Specifically, we now
search for a mismatching element from the back of the subrange we want
to check. When a mismatch occurs we can directly start one after the
mismatched element, since there cannot possibly be a matching subrange
starting between the start of the subrange we checked and the mismatched
element (since all elements have to be equal). The algorithm also
remembers the subrange which was already match as being equal and
doesn't try to compare it a second time, reducing the time spent in case
of a match.

```
Benchmark                                                       old             new    Difference    % Difference
---------------------------------------------------  --------------  --------------  ------------  --------------
rng::search_n(deque<int>)_(no_match)/1000                    458.33           14.22       -444.11         -96.90%
rng::search_n(deque<int>)_(no_match)/1024                    456.17           13.89       -442.28         -96.95%
rng::search_n(deque<int>)_(no_match)/1048576              453420.38           17.69    -453402.69        -100.00%
rng::search_n(deque<int>)_(no_match)/8192                   3566.08           17.60      -3548.49         -99.51%
rng::search_n(deque<int>,_pred)_(no_match)/1000              597.88           15.25       -582.63         -97.45%
rng::search_n(deque<int>,_pred)_(no_match)/1024              608.42           15.39       -593.03         -97.47%
rng::search_n(deque<int>,_pred)_(no_match)/1048576        594533.99           18.91    -594515.08        -100.00%
rng::search_n(deque<int>,_pred)_(no_match)/8192             4670.23           18.88      -4651.35         -99.60%
rng::search_n(list<int>)_(no_match)/1000                     733.72          730.22         -3.50          -0.48%
rng::search_n(list<int>)_(no_match)/1024                     759.93          753.10         -6.84          -0.90%
rng::search_n(list<int>)_(no_match)/1048576               833841.54       813483.75     -20357.79          -2.44%
rng::search_n(list<int>)_(no_match)/8192                    8352.18         8417.31         65.14           0.78%
rng::search_n(list<int>,_pred)_(no_match)/1000               776.79          789.72         12.93           1.66%
rng::search_n(list<int>,_pred)_(no_match)/1024               788.42          806.70         18.28           2.32%
rng::search_n(list<int>,_pred)_(no_match)/1048576         955536.40       982976.81      27440.41           2.87%
rng::search_n(list<int>,_pred)_(no_match)/8192              8874.02         8915.18         41.16           0.46%
rng::search_n(vector<int>)_(no_match)/1000                   212.69            3.79       -208.90         -98.22%
rng::search_n(vector<int>)_(no_match)/1024                   219.67            3.70       -215.96         -98.31%
rng::search_n(vector<int>)_(no_match)/1048576             209622.54            3.67    -209618.87        -100.00%
rng::search_n(vector<int>)_(no_match)/8192                  1643.80            3.83      -1639.98         -99.77%
rng::search_n(vector<int>,_pred)_(no_match)/1000             461.93            7.55       -454.38         -98.36%
rng::search_n(vector<int>,_pred)_(no_match)/1024             472.43            7.74       -464.69         -98.36%
rng::search_n(vector<int>,_pred)_(no_match)/1048576       546180.29            8.71    -546171.58        -100.00%
rng::search_n(vector<int>,_pred)_(no_match)/8192            3786.26            7.88      -3778.38         -99.79%
std::search_n(deque<int>)_(no_match)/1000                    455.53           14.19       -441.34         -96.88%
std::search_n(deque<int>)_(no_match)/1024                    459.79           13.98       -445.81         -96.96%
std::search_n(deque<int>)_(no_match)/1048576              449780.32           17.99    -449762.33        -100.00%
std::search_n(deque<int>)_(no_match)/8192                   3508.55           17.97      -3490.58         -99.49%
std::search_n(deque<int>,_pred)_(no_match)/1000              571.53           17.16       -554.37         -97.00%
std::search_n(deque<int>,_pred)_(no_match)/1024              584.43           17.09       -567.34         -97.08%
std::search_n(deque<int>,_pred)_(no_match)/1048576        581418.31           19.16    -581399.15        -100.00%
std::search_n(deque<int>,_pred)_(no_match)/8192             4661.97           19.36      -4642.61         -99.58%
std::search_n(list<int>)_(no_match)/1000                     722.45          710.39        -12.06          -1.67%
std::search_n(list<int>)_(no_match)/1024                     748.50          727.08        -21.42          -2.86%
std::search_n(list<int>)_(no_match)/1048576               821655.28       784520.12     -37135.16          -4.52%
std::search_n(list<int>)_(no_match)/8192                    7941.73         8002.05         60.32           0.76%
std::search_n(list<int>,_pred)_(no_match)/1000               766.59          786.31         19.72           2.57%
std::search_n(list<int>,_pred)_(no_match)/1024               785.92          804.43         18.51           2.35%
std::search_n(list<int>,_pred)_(no_match)/1048576         948252.76       969125.41      20872.65           2.20%
std::search_n(list<int>,_pred)_(no_match)/8192              8658.99         8825.71        166.72           1.93%
std::search_n(vector<int>)_(no_match)/1000                   210.36            3.47       -206.89         -98.35%
std::search_n(vector<int>)_(no_match)/1024                   217.60            4.13       -213.47         -98.10%
std::search_n(vector<int>)_(no_match)/1048576             209386.43            3.51    -209382.92        -100.00%
std::search_n(vector<int>)_(no_match)/8192                  1643.79            3.50      -1640.29         -99.79%
std::search_n(vector<int>,_pred)_(no_match)/1000             460.88            5.44       -455.45         -98.82%
std::search_n(vector<int>,_pred)_(no_match)/1024             475.36            5.43       -469.93         -98.86%
std::search_n(vector<int>,_pred)_(no_match)/1048576       682722.75            7.15    -682715.60        -100.00%
std::search_n(vector<int>,_pred)_(no_match)/8192            3779.95            5.43      -3774.52         -99.86%
Geomean                                                     4956.15           87.96      -4868.19         -98.23%
```

Fixes #129327
2026-01-08 11:26:08 +01:00
Christopher Di Bella
d10dc5a06f
[libc++] Remove dedicated namespaces for ranges functions (#76543)
We originally put implementation-detail function objects into individual
namespaces for `std::ranges` without a good reason for doing so. This
practice was continued, presumably because there was prior art. Since
there's no reason to keep these namespaces, this commit removes them,
which will slightly impact binary size.

This commit does not apply to CPOs, some of which need additional work.
2024-08-01 08:54:06 -04:00
Nikolas Klauser
83bc7b5771
[libc++] Remove _LIBCPP_DISABLE_NODISCARD_EXTENSIONS and refactor the tests (#87094)
This also adds a few tests that were missing.
2024-04-22 22:13:58 +02:00
Louis Dionne
7b4622514d
[libc++] Fix missing and incorrect push/pop macros (#79204)
We recently noticed that the unwrap_iter.h file was pushing macros, but
it was pushing them again instead of popping them at the end of the
file. This led to libc++ basically swallowing any custom definition of
these macros in user code:

    #define min HELLO
    #include <algorithm>
    // min is not HELLO anymore, it's not defined

While investigating this issue, I noticed that our push/pop pragmas were
actually entirely wrong too. Indeed, instead of pushing macros like
`move`, we'd push `move(int, int)` in the pragma, which is not a valid
macro name. As a result, we would not actually push macros like `move`
-- instead we'd simply undefine them. This led to the following code not
working:

    #define move HELLO
    #include <algorithm>
    // move is not HELLO anymore

Fixing the pragma push/pop incantations led to a cascade of issues
because we use identifiers like `move` in a large number of places, and
all of these headers would now need to do the push/pop dance.

This patch fixes all these issues. First, it adds a check that we don't
swallow important names like min, max, move or refresh as explained
above. This is done by augmenting the existing
system_reserved_names.gen.py test to also check that the macros are what
we expect after including each header.

Second, it fixes the push/pop pragmas to work properly and adds missing
pragmas to all the files I could detect a failure in via the newly added
test.

rdar://121365472
2024-01-25 15:48:46 -05:00
Louis Dionne
5aa03b648b [libc++][NFC] Apply clang-format on large parts of the code base
This commit does a pass of clang-format over files in libc++ that
don't require major changes to conform to our style guide, or for
which we're not overly concerned about conflicting with in-flight
patches or hindering the git blame.

This roughly covers:
- benchmarks
- range algorithms
- concepts
- type traits

I did a manual verification of all the changes, and in particular I
applied clang-format on/off annotations in a few places where the
result was less readable after than before. This was not necessary
in a lot of places, however I did find that clang-format had pretty
bad taste when it comes to formatting concepts.

Differential Revision: https://reviews.llvm.org/D153140
2023-06-19 11:19:51 -04:00
Nikolas Klauser
4f15267d3d [libc++][NFC] Replace _LIBCPP_STD_VER > x with _LIBCPP_STD_VER >= x
This change is almost fully mechanical. The only interesting change is in `generate_feature_test_macro_components.py` to generate `_LIBCPP_STD_VER >=` instead. To avoid churn in the git-blame this commit should be added to the `.git-blame-ignore-revs` once committed.

Reviewed By: ldionne, var-const, #libc

Spies: jloser, libcxx-commits, arichardson, arphaman, wenlei

Differential Revision: https://reviews.llvm.org/D143962
2023-02-15 16:52:25 +01:00
Nikolas Klauser
841399a218 [libc++] Add custom clang-tidy checks
Reviewed By: #libc, ldionne

Spies: jwakely, beanz, smeenai, cfe-commits, tschuett, avogelsgesang, Mordante, sstefan1, libcxx-commits, ldionne, mgorny, arichardson, miyuki

Differential Revision: https://reviews.llvm.org/D131963
2022-12-23 15:42:13 +01:00
Nikolas Klauser
660b243120 [libc++] Add [[nodiscard]] extensions to ranges algorithms
This mirrors what we have done in the classic algorithms

Reviewed By: ldionne, #libc

Spies: libcxx-commits

Differential Revision: https://reviews.llvm.org/D137186
2022-11-05 16:38:46 +01:00
Nikolas Klauser
d5e26775d0 [libc++] Granularize the rest of memory
Reviewed By: ldionne, #libc

Spies: vitalybuka, paulkirth, libcxx-commits, mgorny

Differential Revision: https://reviews.llvm.org/D132790
2022-09-05 12:36:41 +02:00
Vitaly Buka
bc8fd9c633 Revert "[libc++] Granularize the rest of memory"
Breaks buildbots.

This reverts commit 30adaa730c4768b5eb06719c808b2884fcf53cf3.
2022-09-02 19:42:49 -07:00
Nikolas Klauser
30adaa730c [libc++] Granularize the rest of memory
Reviewed By: ldionne, #libc

Spies: libcxx-commits, mgorny

Differential Revision: https://reviews.llvm.org/D132790
2022-09-02 21:42:41 +02:00
Louis Dionne
b8cb1dc9ea [libc++] Make <ranges> non-experimental
When we ship LLVM 16, <ranges> won't be considered experimental anymore.
We might as well do this sooner rather than later.

Differential Revision: https://reviews.llvm.org/D132151
2022-08-18 16:59:58 -04:00
Nikolas Klauser
101d1e9b3c [libc++] Implement ranges::find_end, ranges::search{, _n}
Reviewed By: var-const, #libc, huixie90

Spies: thakis, h-vetinari, huixie90, libcxx-commits, mgorny

Differential Revision: https://reviews.llvm.org/D124079
2022-07-13 20:30:55 +02:00
Nikolas Klauser
1f04759316 Revert "[libc++] Implement ranges::find_end, ranges::search{, _n}"
This reverts commit 76a76518507ccc59ccdad5b83f44dc8c3d9593c7.
2022-07-13 13:41:25 +02:00
Nikolas Klauser
76a7651850 [libc++] Implement ranges::find_end, ranges::search{, _n}
Reviewed By: var-const, #libc, huixie90

Spies: h-vetinari, huixie90, libcxx-commits, mgorny

Differential Revision: https://reviews.llvm.org/D124079
2022-07-13 13:11:26 +02:00