C++20 revised the definition of what it means to be an iterator. While
all _Cpp17InputIterators_ satisfy `std::input_iterator`, the reverse
isn't true. D100271 introduces a new test adaptor to accommodate this
new definition (`cpp20_input_iterator`).
In order to help readers immediately distinguish which input iterator
adaptor is _Cpp17InputIterator_, the current `input_iterator` adaptor
has been prefixed with `cpp17_`.
Differential Revision: https://reviews.llvm.org/D101242
While working on D70631, Microsoft's unit tests discovered an issue.
Our `std::to_chars` implementation for bases != 10 uses the range
`[first,last)` as temporary buffer. This violates the contract for
to_chars:
[charconv.to.chars]/1 http://eel.is/c++draft/charconv#to.chars-1
`to_chars_result to_chars(char* first, char* last, see below value, int base = 10);`
"If the member ec of the return value is such that the value is equal to
the value of a value-initialized errc, the conversion was successful and
the member ptr is the one-past-the-end pointer of the characters
written."
Our implementation modifies the range `[member ptr, last)`, which causes
Microsoft's test to fail. Their test verifies the buffer
`[member ptr, last)` is unchanged. (The test is only done when the
conversion is successful.)
While looking at the code I noticed the performance for bases != 10 also
is suboptimal. This is tracked in D97705.
This patch fixes the issue and adds a benchmark. This benchmark will be
used as baseline for D97705.
Reviewed By: #libc, Quuxplusone, zoecarver
Differential Revision: https://reviews.llvm.org/D100722
When using the per-target runtime build, it may be desirable to have
different __config_site headers for each target where all targets cannot
share a single configuration.
The layout used for libc++ headers after this change is:
```
include/
c++/
v1/
<libc++ headers except for __config_site>
<target1>/
c++/
v1/
__config_site
<target2>/
c++/
v1/
__config_site
<other targets>
```
This is the most optimal layout since it avoids duplication, the only
headers that's per-target is __config_site, all other headers are
shared across targets. This also means that we no need two
-isystem flags: one for the target-agnostic headers and one for
the target specific headers.
Differential Revision: https://reviews.llvm.org/D89013
Prior to this patch, we would generate a fancy <__config> header by
concatenating <__config_site> and <__config>. This complexifies the
build system and also increases the difference between what's tested
and what's actually installed.
This patch removes that complexity and instead simply installs <__config_site>
alongside the libc++ headers. <__config_site> is then included by <__config>,
which is much simpler. Doing this also opens the door to having different
<__config_site> headers depending on the target, which was impossible before.
It does change the workflow for testing header-only changes to libc++.
Previously, we would run `lit` against the headers in libcxx/include.
After this patch, we run it against a fake installation root of the
headers (containing a proper <__config_site> header). This makes use
closer to testing what we actually install, which is good, however it
does mean that we have to update that root before testing header changes.
Thus, we now need to run `ninja check-cxx-deps` before running `lit` by
hand.
Differential Revision: https://reviews.llvm.org/D97572
Some work-in-progress patches for the format header contain benchmarks.
The format header requires C++20 to build. This is a preparation to make
it easy to add these benchmarks.
Reviewed By: ldionne, #libc
Differential Revision: https://reviews.llvm.org/D96057
This is a massive revert of the following commits (from most revent to oldest):
2b9b7b5775.
529ac3319728270234f169c2087283b5aa67446e5d796645d6
After checking-in the __config_site change, a lot of things started breaking
due to widespread reliance on various aspects of libc++'s build, notably the
fact that we can include the headers from the source tree, but also reliance
on various "internal" CMake variables used by the runtimes build and compiler-rt.
These were unintended consequences of the change, and after two days, we
still haven't restored all the bots to being green. Instead, now that I
understand what specific areas this will blow up in, I should be able to
chop up the patch into smaller ones that are easier to digest.
See https://reviews.llvm.org/D89041 for more details on this adventure.
The benchmarks expect to be built in C++17 or newer, but this
isn't always how CMake configures the C++ dialect. Instead
we need to explicitly set the CXX_STANDARD target property.
Summary:
Modifies the algorithm sort bench:
- shows sorting time per element, instead of sorting time per array.
This would make comparison between different sizes of arrays easier.
- adds std::pair benchmark cases.
- uses a large number of arrays to benchmark, instead of repeatedly sorting the same array.
* sorting the same array again and again would not show actual sorting performance over randomized data sets.
Reviewers: EricWF, #libc, mvels
Reviewed By: EricWF, #libc, mvels
Subscribers: mgrang, libcxx-commits
Tags: #libc
Differential Revision: https://reviews.llvm.org/D81770
Before this patch, the __config_site header was only generated when at
least one __config_site macro needed to be defined. This lead to two
different code paths in how libc++ is configured, depending on whether
a __config_site header was generated or not. After this patch, the
__config_site is always generated, but it can be empty in case there
are no macros to define in it.
More context on why this change is important
--------------------------------------------
In addition to being confusing, this double-code-path situation lead to
broken code being checked in undetected in 2405bd6898, which introduced
the LIBCXX_HAS_MERGED_TYPEINFO_NAMES_DEFAULT CMake setting. Specifically,
the _LIBCPP_HAS_MERGED_TYPEINFO_NAMES_DEFAULT <__config_site> macro was
supposed NOT to be defined unless LIBCXX_HAS_MERGED_TYPEINFO_NAMES_DEFAULT
was specified explicitly on the CMake command line. Instead, what happened
is that it was defined to 0 if it wasn't specified explicitly and a
<__config_site> header was generated. And defining that macro to 0 had
the important effect of using the non-unique RTTI comparison implementation,
which changes the ABI.
This change in behavior wasn't noticed because the <__config_site> header
is not generated by default. However, the Apple configuration does cause
a <__config_site> header to be generated, which lead to the wrong RTTI
implementation being used, and to https://llvm.org/PR45549. We came close
to an ABI break in the dylib, but were saved due to a downstream-only
change that overrode the decision of the <__config_site> for the purpose
of RTTI comparisons in libc++abi. This is an incredible luck that we should
not rely on ever again.
While the problem itself was fixed with 2464d8135e by setting
LIBCXX_HAS_MERGED_TYPEINFO_NAMES_DEFAULT explicitly in the Apple
CMake cache and then in d0fcdcd28f by making the setting less
brittle, the point still is that we should have had a single code
path from the beginning. Unlike most normal libraries, the macros
that configure libc++ are really complex, there's a lot of them and
they control important properties of the C++ runtime. There must be
a single code path for that, and it must be simple and robust.
Differential Revision: https://reviews.llvm.org/D80927
The benchmarks are intended to be build with C++17 but the
CMAKE_CXX_STANDARD in the LLVM forces the build to use C++14 by default.
This fixes the issue by setting the CXX_STANDARD property of the benchmark
targets.
The CMake documentation is not clear whether this will use the C++1z
fallback for older compilers. So this may break the benchmarks if somebody
uses the benchmarks with pre C++17 compilers with the C++1z fallback.
Differential Revision: https://reviews.llvm.org/D75955
This change adds the following benchmarks:
- StringAssignStr
Assign a const basic::string& value
- StringAssignAsciiz
Assign a const char* asciiz value
StringAssignAsciizMix
Assign mixed long/short const char* asciiz values
- StringResizeDefaultInit
Resize default init benchmark
Patch by Martijn Vels (mvels@google.com)
Reviewed as D72343
It turns out that r374056 broke _some_ build bots again, specifically
the ones using sanitizers. Instead of trying to link the right system
libraries to the benchmarks bit-by-bit, let's just link exactly the
system libraries that libc++ itself needs.
llvm-svn: 374079
Since the benchmarks build with -nostdlib, they need to manually link
against some system libraries that are used by the benchmarks and the
GoogleBenchmark library itself.
Previously, we'd rely on the fact that these libraries were linked
through the PUBLIC dependencies of cxx_shared/cxx_static. However,
if we were to make these dependencies PRIVATE (as they should be
because they are implementation details of libc++), the benchmarks
would fail to link. This commit remediates that.
llvm-svn: 374053
It's better style to use PRIVATE when linking libraries to executables,
and it doesn't make a difference since executables don't need to propagate
their link-time dependencies anyway.
llvm-svn: 374050
This allows propagating the include automatically to targets that
depend on one of the libc++ targets such as the benchmarks. Note
that the GoogleBenchmark build itself still needs to manually specify
the -include, since I don't know of any way to have an external project
link against one of the libc++ targets (which would propagate the -include
automatically).
llvm-svn: 373631
This patch rewrites a few loops in deque and split_buffer to better
optimize the codegen. For constructors like
`deque<unsigned char> d(500000, 0);` this patch results in a 2x speedup.
The patch improves the codegen in roughly three ways:
1. Changes do { ... } while (...) loops into more typical for loops.
The optimizer can reason about normal looking loops better.
2. Split the iteration over a range into (A) iteration over the blocks,
then (B) iteration within the block. This nested structure helps LLVM
lower the inner loop to `memset`.
3. Do fewer things each iteration. Some of these loops were incrementing
or changing 4-5 variables every loop (in addition to the
construction). Previously most loops would increment the end pointer,
the size, and decrement the count of remaining items to construct.
Now we only increment a single pointer for most iterations.
llvm-svn: 368547
The optimizer is petulant and temperamental. In this case LLVM failed to lower
the the "insert at end" loop used by`vector<unsigned char>` to a `memset` despite
`memset` being substantially faster over a range of bytes.
LLVM has the ability to lower loops to `memset` whet appropriate, but the
odd nature of libc++'s loops prevented the optimization from taking places.
This patch addresses the issue by rewriting the loops from the form
`do [ ... --__n; } while (__n > 0);` to instead use a for loop over a pointer
range (For example: `for (auto *__i = ...; __i < __e; ++__i)`).
This patch also rewrites the asan annotations to unposion all additional memory
at the start of the loop instead of once per iterations. This could potentially
permit false negatives where the constructor of element N attempts to access
element N + 1 during its construction.
The before and after results for the `BM_ConstructSize/vector_byte/5140480_mean`
benchmark (run 5 times) are:
--------------------------------------------------------------------------------------------
Benchmark Time CPU Iterations
--------------------------------------------------------------------------------------------
Before
------
BM_ConstructSize/vector_byte/5140480_mean 12530140 ns 12469693 ns N/A
BM_ConstructSize/vector_byte/5140480_median 12512818 ns 12445571 ns N/A
BM_ConstructSize/vector_byte/5140480_stddev 106224 ns 107907 ns 5
-----
After
-----
BM_ConstructSize/vector_byte/5140480_mean 167285 ns 166500 ns N/A
BM_ConstructSize/vector_byte/5140480_median 166749 ns 166069 ns N/A
BM_ConstructSize/vector_byte/5140480_stddev 3242 ns 3184 ns 5
llvm-svn: 367183
Summary:
Instead of populating the global LIBCXX_LIBRARIES, we use the link-time
dependency management built into CMake to propagate link flags. This
leads to a cleaner and easier-to-follow build.
Reviewers: phosek, smeenai, EricWF
Subscribers: mgorny, christof, jkorous, dexonsmith, jfb, mstorsjo, libcxx-commits
Tags: #libc
Differential Revision: https://reviews.llvm.org/D60969
llvm-svn: 359571
Summary:
Comparing against the empty string should generate much better code that
what it does today.
We can also generate better code when comparing against literals that
are larger than the SSO space.
Reviewers: EricWF
Subscribers: christof, jdoerfert, libcxx-commits
Tags: #libc
Differential Revision: https://reviews.llvm.org/D59781
llvm-svn: 357614
Summary:
Add relational benchmark against a string constant.
These can potentially trigger inlining of the operations. We want to
benchmark that.
Reviewers: EricWF
Subscribers: christof, jdoerfert, libcxx-commits
Tags: #libc
Differential Revision: https://reviews.llvm.org/D59512
llvm-svn: 356680
Summary:
This patch treats <filesystem> as a first-class citizen of the dylib,
like all other sub-libraries (e.g. <chrono>). As such, it also removes
all special handling for installing the filesystem library separately
or disabling part of the test suite from the lit command line.
Unlike the previous attempt (r356500), this doesn't remove all the
filesystem tests.
Reviewers: mclow.lists, EricWF, serge-sans-paille
Subscribers: mgorny, christof, jkorous, dexonsmith, jfb, jdoerfert, libcxx-commits
Differential Revision: https://reviews.llvm.org/D59152
llvm-svn: 356518
When I applied r356500 (https://reviews.llvm.org/D59152), I somehow
deleted all of filesystem's tests. I will revert r356500 and re-apply
it properly.
llvm-svn: 356505
Summary:
This patch treats <filesystem> as a first-class citizen of the dylib,
like all other sub-libraries (e.g. <chrono>). As such, it also removes
all special handling for installing the filesystem library separately
or disabling part of the test suite from the lit command line.
Reviewers: mclow.lists, EricWF, serge-sans-paille
Subscribers: mgorny, christof, jkorous, dexonsmith, jfb, jdoerfert, libcxx-commits
Differential Revision: https://reviews.llvm.org/D59152
llvm-svn: 356500
When linking library dependencies, we shouldn't need to export linked
libraries to dependents. We should be explicit about this in
target_link_libraries, otherwise other targets that depend on these such
as sanitizers get repeated (and possibly even conflicting) dependencies.
Differential Revision: https://reviews.llvm.org/D57456
llvm-svn: 352688
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
This is a re-application of r345525, which had been reverted by fear of
a regression.
Reviewed as https://reviews.llvm.org/D53994.
Thanks to Denis Yaroshevskiy for the patch.
llvm-svn: 349358
Summary:
Benchmarks for std::sort, std::stable_sort, std::make_heap,
std::sort_heap, std::pop_heap and std::push_heap.
The benchmarks are run with integers and strings, and with different
sorted input.
Reviewers: EricWF
Subscribers: christof, mgrang, ldionne, libcxx-commits
Differential Revision: https://reviews.llvm.org/D53978
llvm-svn: 347329
This patch renames the cxx-benchmark-unittests to check-cxx-benchmarks
and converts the target to use LIT in order to make the tests run faster
and provide better output.
In particular this runs each benchmark in a suite one by one, allowing
more parallelism while ensuring output isn't garbage with multiple threads.
Additionally, it adds the CMake flag '-DLIBCXX_BENCHMARK_TEST_ARGS=<list>'
to specify what options are passed when running the benchmarks.
llvm-svn: 346888
This patch adds the cxx-benchmark-unittests target so we can start
getting test coverage on the benchmarks, including building with
sanitizers. Because we're only looking for test-coverage, the benchmarks
run for the shortest time possible, and in parallel.
The target is excluded from all by default. It only
builds and runs the libcxx configurations of the benchmarks, and not
any versions built against the systems native standard library.
llvm-svn: 346811
Christopher Di Bella