On Apple platforms, arc4random is faster than /dev/urandom, and it is
the recommended user-space RNG according to Apple's own OS folks.
This commit adds an ABI switch to guard ABI-break-protections in
std::random_device, and starts using arc4random instead of /dev/urandom
to implement std::random_device on Apple platforms.
Note that previously, `std::random_device` would allow passing a custom
token to its constructor, and that token would be interpreted as the name
of a file to read entropy from. This was implementation-defined and
undocumented. After this change, Apple platforms will be using arc4random()
instead, and any custom token passed to the constructor will be ignored.
This behavioral change will also impact other platforms that use the
arc4random() implementation, such as OpenBSD. This should be fine since
that is effectively a relaxation of the constructor's requirements.
rdar://86638350
Differential Revision: https://reviews.llvm.org/D116045
The documentation CI job is very cheap, so we can afford to keep it
around even with reduced capacity. This commit fixes the documentation
(which had an invalid reference in it) and re-enables that CI step.
Differential Revision: https://reviews.llvm.org/D116897
Although we moved to Github Issues. The bug report message refers to
Bugzilla still. This patch tries to update these URLs.
Reviewed By: MaskRay, Quuxplusone, jhenderson, libunwind, libc++
Differential Revision: https://reviews.llvm.org/D116351
`__cpp_lib_type_identity` was implemented way back in cf49ccd0 (Clang 8),
probably before the feature-test macro had been settled on.
`__cpp_lib_string_resize_and_overwrite` will be added by D113013 so I didn't add it here.
Fixes#46605.
Differential Revision: https://reviews.llvm.org/D116433
We didn't support noop_coroutine for GCC in previous conforming patch.
So that GCC couldn't use noop_coroutine() defined in <coroutine>. And
after this patch, GCC should be able to compile the whole <coroutine>
header.
Reviewed By: Quuxplusone
Differential Revision: https://reviews.llvm.org/D116144
Clang is gaining `auto(x)` support in D113393; sadly there
seems to be no feature-test macro for it. Zhihao is opening
a core issue for that macro.
Use `_LIBCPP_AUTO_CAST` where C++20 specifies we should use `auto(x)`;
stop using `__decay_copy(x)` in those places.
In fact, remove `__decay_copy` entirely. As of C++20, it's purely
a paper specification tool signifying "Return just `x`, but it was
perfect-forwarded, so we understand you're going to have to call
its move-constructor sometimes." I believe there's no reason we'd
ever need to do its operation explicitly in code.
This heisenbugs away a test failure on MinGW; see D112214.
Differential Revision: https://reviews.llvm.org/D115686
When P0883R2 was initially implemented in D103769 #pragma clang deprecated didn't exist yet.
We also forgot to cleanup usages in libc++ itself.
This takes care of both.
Differential Revision: https://reviews.llvm.org/D115995
Also:
- refactor out `__voidify`;
- use the `destroy` algorithm internally;
- refactor out helper classes used in tests for `uninitialized_*`
algorithms.
Differential Revision: https://reviews.llvm.org/D115626
Defined in [`specialized.algorithms`](wg21.link/specialized.algorithms).
Also:
- refactor the existing non-range implementation so that most of it
can be shared between the range-based and non-range-based algorithms;
- remove an existing test for the non-range version of
`uninitialized_default_construct{,_n}` that likely triggered undefined
behavior (it read the values of built-ins after default-initializing
them, essentially reading uninitialized memory).
Reviewed By: #libc, Quuxplusone, ldionne
Differential Revision: https://reviews.llvm.org/D115315
Microsoft would like to contribute its implementation of floating-point to_chars to libc++. This uses the impossibly fast Ryu and Ryu Printf algorithms invented by Ulf Adams at Google. Upstream repos: https://github.com/microsoft/STL and https://github.com/ulfjack/ryu .
Licensing notes: MSVC's STL is available under the Apache License v2.0 with LLVM Exception, intentionally chosen to match libc++. We've used Ryu under the Boost Software License.
This patch contains minor changes from Jorg Brown at Google, to adapt the code to libc++. He verified that it works in Google's Linux-based environment, but then I applied more changes on top of his, so any compiler errors are my fault. (I haven't tried to build and test libc++ yet.) Please tell me if we need to do anything else in order to follow https://llvm.org/docs/DeveloperPolicy.html#attribution-of-changes .
Notes:
* libc++'s integer charconv is unchanged (except for a small refactoring). MSVC's integer charconv hasn't been tuned for performance yet, so you're not missing anything.
* Floating-point from_chars isn't part of this patch because Jorg found that MSVC's implementation (derived from our CRT's strtod) was slower than Abseil's. If you're unable to use Abseil or another implementation due to licensing or technical considerations, Microsoft would be delighted if you used MSVC's from_chars (and you can just take it, or ask us to provide a patch like this). Ulf is also working on a novel algorithm for from_chars.
* This assumes that float is IEEE 32-bit, double is IEEE 64-bit, and long double is also IEEE 64-bit.
* I have added MSVC's charconv tests (the whole thing: integer/floating from_chars/to_chars), but haven't adapted them to libcxx's harness at all. (These tests will be available in the microsoft/STL repo soon.)
* Jorg added int128 codepaths. These were originally present in upstream Ryu, and I removed them from microsoft/STL purely for performance reasons (MSVC doesn't support int128; Clang on Windows does, but I found that x64 intrinsics were slightly faster).
* The implementation is split into 3 headers. In MSVC's STL, charconv contains only Microsoft-written code. xcharconv_ryu.h contains code derived from Ryu (with significant modifications and additions). xcharconv_ryu_tables.h contains Ryu's large lookup tables (they were sufficiently large to make editing inconvenient, hence the separate file). The xmeow.h convention is MSVC's for internal headers; you may wish to rename them.
* You should consider separately compiling the lookup tables (see https://github.com/microsoft/STL/issues/172 ) for compiler throughput and reduced object file size.
* See https://github.com/StephanTLavavej/llvm-project/commits/charconv for fine-grained history. (If necessary, I can perform some rebase surgery to show you what Jorg changed relative to the microsoft/STL repo; currently that's all fused into the first commit.)
Differential Revision: https://reviews.llvm.org/D70631
There's a lot of history behind this, so here's a summary:
1. I stopped forcing -fPIC when building the runtimes in 30f305efe2,
before the LLVM 9 release back in 2019.
2. Someone complained that libc++.a couldn't be used in shared libraries
built without -fPIC (http://llvm.org/PR43604) since the LLVM 9 release.
This had been caused by my removal of -fPIC when building libc++.a in (1).
3. I suggested two ways of fixing the issue, the first being to force
-fPIC back unconditionally (http://llvm.org/D104328), and the second
being to specify that option explicitly when building the LLVM release
(http://llvm.org/D104327). We converged on the first solution.
4. I landed D104328, which forced building the runtimes with -fPIC.
This was included in the LLVM 13.0 release.
5. People complained about that and requested that we be able to
customize this setting (basically we should have done the second
solution).
This patch makes it such that the LLVM release script will specifically
ask for building with -fPIC using CMAKE_POSITION_INDEPENDENT_CODE,
however by default the runtimes will not force that option onto users.
This patch has the unintended effect that Clang and the LLVM libraries
(not only the runtime ones like libc++) will also be built with -fPIC
in the release. It would be better if we could specify that -fPIC is to
be used only when building the runtimes, however this is left as a
future improvement. The release should probably be using a bootstrapping
build and passing those options to the stage that builds the runtimes
only, see https://reviews.llvm.org/D112748 for that change.
Differential Revision: https://reviews.llvm.org/D110261
Microsoft would like to contribute its implementation of floating-point to_chars to libc++. This uses the impossibly fast Ryu and Ryu Printf algorithms invented by Ulf Adams at Google. Upstream repos: https://github.com/microsoft/STL and https://github.com/ulfjack/ryu .
Licensing notes: MSVC's STL is available under the Apache License v2.0 with LLVM Exception, intentionally chosen to match libc++. We've used Ryu under the Boost Software License.
This patch contains minor changes from Jorg Brown at Google, to adapt the code to libc++. He verified that it works in Google's Linux-based environment, but then I applied more changes on top of his, so any compiler errors are my fault. (I haven't tried to build and test libc++ yet.) Please tell me if we need to do anything else in order to follow https://llvm.org/docs/DeveloperPolicy.html#attribution-of-changes .
Notes:
* libc++'s integer charconv is unchanged (except for a small refactoring). MSVC's integer charconv hasn't been tuned for performance yet, so you're not missing anything.
* Floating-point from_chars isn't part of this patch because Jorg found that MSVC's implementation (derived from our CRT's strtod) was slower than Abseil's. If you're unable to use Abseil or another implementation due to licensing or technical considerations, Microsoft would be delighted if you used MSVC's from_chars (and you can just take it, or ask us to provide a patch like this). Ulf is also working on a novel algorithm for from_chars.
* This assumes that float is IEEE 32-bit, double is IEEE 64-bit, and long double is also IEEE 64-bit.
* I have added MSVC's charconv tests (the whole thing: integer/floating from_chars/to_chars), but haven't adapted them to libcxx's harness at all. (These tests will be available in the microsoft/STL repo soon.)
* Jorg added int128 codepaths. These were originally present in upstream Ryu, and I removed them from microsoft/STL purely for performance reasons (MSVC doesn't support int128; Clang on Windows does, but I found that x64 intrinsics were slightly faster).
* The implementation is split into 3 headers. In MSVC's STL, charconv contains only Microsoft-written code. xcharconv_ryu.h contains code derived from Ryu (with significant modifications and additions). xcharconv_ryu_tables.h contains Ryu's large lookup tables (they were sufficiently large to make editing inconvenient, hence the separate file). The xmeow.h convention is MSVC's for internal headers; you may wish to rename them.
* You should consider separately compiling the lookup tables (see https://github.com/microsoft/STL/issues/172 ) for compiler throughput and reduced object file size.
* See https://github.com/StephanTLavavej/llvm-project/commits/charconv for fine-grained history. (If necessary, I can perform some rebase surgery to show you what Jorg changed relative to the microsoft/STL repo; currently that's all fused into the first commit.)
Differential Revision: https://reviews.llvm.org/D70631
Implement the exposition-only concepts specified in
`[special.mem.concepts]`. These are all thin wrappers over other
concepts.
Reviewed By: #libc, Quuxplusone, ldionne
Differential Revision: https://reviews.llvm.org/D114761
Implement P1989R2 which adds a range constructor for `string_view`.
Adjust `operator/=` in `path` to avoid atomic constraints caching issue
getting provoked from this PR.
Add defaulted template argument to `string_view`'s "sufficient
overloads" to avoid mangling issues in `clang-cl` builds. It is a
MSVC mangling bug that this works around.
Differential Revision: https://reviews.llvm.org/D113161
This patch removes the ability to build the runtimes in the 32 bit
multilib configuration, i.e. using -m32. Instead of doing this, one
should cross-compile the runtimes for the appropriate target triple,
like we do for all other triples.
As it stands, -m32 has several issues, which all seem to be related to
the fact that it's not well supported by the operating systems that
libc++ support. The simplest path towards fixing this is to remove
support for the configuration, which is also the best course of action
if there is little interest for keeping that configuration. If there
is a desire to keep this configuration around, we'll need to do some
work to figure out the underlying issues and fix them.
Differential Revision: https://reviews.llvm.org/D114473
This removes the `format_args_t` from `<format>` and adjusts the type of
the `format_args` for the `vformat_to` overloads.
The `format_context` uses a `back_insert_iterator<string>` therefore the
new `output_iterator` function uses a `string` as its temporary storage
buffer. This isn't ideal. The next patches in this series will improve
this. These improvements make it easy to also improve `format_to_n` and
`formatted_size`.
This addresses P2216 `6. Binary size`.
P2216 `5. Compile-time checks` are not part of this change.
Implements parts of:
- P2216 std::format improvements
Depends on D103670
Reviewed By: ldionne, #libc
Differential Revision: https://reviews.llvm.org/D110494
We only support Clangs that implement nullptr as an extension in C++03 mode,
and we don't support GCC in C++03 mode. Hence, this patch disables the
use of the std::nullptr_t emulation in C++03 mode by default. Doing that
is technically an ABI break since it changes the mangling for std::nullptr_t.
However:
(1) The only affected users are those compiling in C++03 mode that have
std::nullptr_t as part of their ABI, which should be reasonably rare.
(2) Those users already have a lingering problem in that their code will
be incompatible in C++03 and C++11 modes because of that very ABI break.
Hence, the only users that could really be inconvenienced about this
change is those that planned on compiling in C++03 mode forever - for
other users, we're just breaking them now instead of letting them break
themselves later on when they try to upgrade to C++11.
(3) The ABI break will cause a linker error since the mangling changed,
and will not result in an obscure runtime error.
Furthermore, if anyone is broken by this, they can define the
_LIBCPP_ABI_USE_CXX03_NULLPTR_EMULATION macro to return to the
previous behavior. We will then remove that macro after shipping
this for one release if we haven't seen widespread issues.
Concretely, the motivation for making this change is to make our own ABI
consistent in C++03 and C++11 modes and to remove complexity around the
definition of nullptr.
Furthermore, we could investigate making nullptr a keyword in C++03 mode
as a Clang extension -- I don't think that would break anyone, since
libc++ already defines nullptr as a macro to something else. Only users
that do not use libc++ and compile in C++03 mode could potentially be
broken by that.
Differential Revision: https://reviews.llvm.org/D109459
This does not include `std::compare_*_fallback`; those are coming later.
There's still an open question of how to implement std::strong_order
for `long double`, which has 80 value bits and 48 padding bits on x86-64,
and which is presumably *not* IEEE 754-compliant on PPC64 and so on.
So that part is left unimplemented.
Differential Revision: https://reviews.llvm.org/D110738
Mark [cmp.concept] implementation as completed in our documentation.
Reviewed By: ldionne, #libc
Differential Revision: https://reviews.llvm.org/D114203
We've stopped doing it in libc++ for a while now because these names
would end up rotting as we move things around and copy/paste stuff.
This cleans up all the existing files so as to stop the spreading
as people copy-paste headers around.
Mention support for MinGW in the docs. Rename the existing windows
CI jobs to Clang-cl, as both Clang-cl and MinGW are equally much
"Windows", just different toolchain environments.
Add an XFAIL for a recently added test that fails in the MinGW DLL
configuration (with an explanation of what's causing the failure).
Differential Revision: https://reviews.llvm.org/D112215
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
Since coroutine is merged in C++ standard and the support for coroutine
seems relatively stable. It's the time to move the implementation of
coroutine out of the experimental directory and the std::experimental
namespace. This patch creates header <coroutine> with conformed
implementation with C++ standard. To avoid breaking user's code too
fast, the <experimental/coroutine> header is remained. Note that
<experimental/coroutine> is deprecated and it would be removed in
LLVM15.
Reviewed By: Quuxplusone, ldionne
Differential Revision: https://reviews.llvm.org/D109433
Konstantin Varlamov