Same idea as the current algorithm, that is, add (half of the difference between a and b) to a.
But we use a different technique for computing the difference: we compute b - a into a pair of integers that are named "sign_bit" and "diff". We have to use a pair because subtracting two 32-bit integers produces a 33-bit result.
Computing half of that is a simple matter of shifting diff right by 1, and adding sign_bit shifted left by 31. llvm knows how to do that with one instruction: shld.
The only tricky part is that if the difference is odd and negative, then shifting it by one isn't the same as dividing it by two - shifting a negative one produces a negative one, for example. So there's one more adjustment: if the sign bit and the low bit of diff are one, we add one.
For a demonstration of the codegen difference, see https://godbolt.org/z/7ar3K9 , which also has a built-in test.
Differential Revision: https://reviews.llvm.org/D69459
Use the builtin CMake support for specifying the proper flags for the targets to
build at a certain C++ standard. This avoids unnecessary checks in CMake,
speeding up the configure phase as well as simplifies the logic overall.
PR13592 was caused by a problem in how to compiler implemented the
__is_convertible_to intrinsic. That problem, reported as PR13591,
was fixed back in 2012. We don't support such old versions of Clang
anyway, so we don't need the library workaround that had been added
to solve PR13592 (while waiting for the compiler fix).
Summary:
When the ABI namespace isn't a reserved identifier, we were issuing a
warning, but this should have been an error since the beginning. This
commit enforces that the ABI namespace is a reserved identifier, and
changes the ABI namespace used by LibFuzzer.
Reviewers: phosek, EricWF
Subscribers: mgorny, christof, jkorous, dexonsmith, #sanitizers, libcxx-commits, llvm-commits
Tags: #sanitizers, #libc, #llvm
Differential Revision: https://reviews.llvm.org/D69408
When running libc++ tests on a remote machine via SSH, we can encounter
a 'Permission denied' error.
Fix this with plain old 'chmod +x <executable>'.
Thanks to Sergej Jaskiewicz for the patch.
Differential Revision: https://reviews.llvm.org/D69170
Summary: This patch removes `shared_ptr::make_shared` as it is not part of the standard. This patch also adds __create_with_cntrl_block, which is a help function that can be used in std::allocate_shared and std::make_shared. This is the third patch (out of 4) from D66178.
Reviewers: EricWF, mclow.lists, ldionne
Subscribers: christof, dexonsmith, libcxx-commits
Tags: #libc
Differential Revision: https://reviews.llvm.org/D68805
llvm-svn: 375504
Summary:
In D67316 we added `_LIBCPP_C_HAS_NO_GETS` to signal that the C library
does not provide `gets()`, and added a test for FreeBSD 13 or higher,
using the compiler-defined `__FreeBSD__` macro.
Unfortunately this did not work that well for FreeBSD's own CI process,
since the gcc compilers used for some architectures define `__FreeBSD__`
to match the build host, not the target.
Instead, we should use the `__FreeBSD_version` macro from the userland
header `<osreldate.h>`, which is more fine-grained. See also
<https://reviews.freebsd.org/D22034>.
Reviewers: EricWF, mclow.lists, emaste, ldionne
Reviewed By: emaste, ldionne
Subscribers: dexonsmith, bsdjhb, krytarowski, christof, ldionne, libcxx-commits
Differential Revision: https://reviews.llvm.org/D69174
llvm-svn: 375340
Summary: The implementation of P1152R4 in Clang has resulted in some deprecation warnings appearing in the libc++ and libc++abi test suite. Fix or suppress these warnings.
Reviewers: mclow.lists, EricWF
Subscribers: christof, ldionne, libcxx-commits
Tags: #libc
Differential Revision: https://reviews.llvm.org/D68879
llvm-svn: 375307
* Add the conventional `return 0` to `main` in `variant.assign/conv.pass.cpp` and `variant.ctor/conv.pass.cpp`
* Fix some MSVC signed-to-unsigned conversion warnings by replacing `int` literarls with `unsigned int` literals
llvm-svn: 374723
`make_optional<string>(4, 'X')` passes `4` (an `int`) as the first argument to `string`'s `(size_t, charT)` constructor, triggering a signed/unsigned mismatch warning when compiling with MSVC at `/W4`. The incredibly simple fix is to instead use an unsigned literal (`4u`).
llvm-svn: 374684
Handle the case when libc++abi and libunwind are being built together
with libc++ in the runtimes build. This logic was used in the previous
implementation but dropped in r374116.
Differential Revision: https://reviews.llvm.org/D68791
llvm-svn: 374510
`sizeof(std::any) - sizeof(void*)` is correct for both libc++ and the MSVC standard library.
Differential Revision: https://reviews.llvm.org/D68756
llvm-svn: 374407
* Silence unused-local-typedef warnings: `map.cons/assign_initializer_list.pass.cpp` (and the `set.cons` variant) uses a local typedef only within `LIBCPP_ASSERT`s, so clang diagnoses it as unused when testing non-libc++.
* Add missing include: `c.math/abs.pass.cpp` uses `std::numeric_limits` but failed to `#include <limits>`.
* Don't test non-type: A "recent" change to `meta.trans.other/underlying_type.pass.cpp` unconditionally tests the type `F` which is conditionally defined.
* Use `hash<long long>` instead of `hash<short>` with `int` in `unordered_meow` deduction guide tests to avoid truncation warnings.
* Convert `3.14` explicitly in `midpoint.float.pass` since MSVC incorrectly diagnoses `float meow = 3.14;` as truncating.
Differential Revision: https://reviews.llvm.org/D68681
llvm-svn: 374248
Summary:
This allows the linker script generation to query CMake properties
(specifically the dependencies of libc++.so) instead of having to
carry these dependencies around manually in global variables. Notice
the removal of the LIBCXX_INTERFACE_LIBRARIES global variable.
Reviewers: phosek, EricWF
Subscribers: mgorny, christof, jkorous, dexonsmith, libcxx-commits
Tags: #libc
Differential Revision: https://reviews.llvm.org/D68343
llvm-svn: 374116
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
We tried doing that previously (in r373487) and failed (reverted in
r373506) because the benchmarks needed to link against system libraries
and relied on libc++'s dependencies being propagated. Now that this has
been fixed (in r374053), this commit marks the system libraries as
PRIVATE dependencies of libc++.
llvm-svn: 374056
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
Summary: In my last patch (D67675) I forgot a few variadics. This patch removes the remaining make_shared and allocate_shared C++03 variadics.
Reviewers: ldionne, EricWF, mclow.lists
Subscribers: christof, dexonsmith, libcxx-commits
Tags: #libc
Differential Revision: https://reviews.llvm.org/D68000
llvm-svn: 373971
If you explicitly set LIBCXX_ENABLE_EXPERIMENTAL_LIBRARY to OFF, your
project will fail to configure because the cxx_experimental target
doesn't exist.
llvm-svn: 373809
Also, set those flags for the cxx_experimental target. Otherwise,
cxx_experimental doesn't build properly when neither the static nor
the shared library is compiled (yes, that is a weird setup).
llvm-svn: 373808
Summary:
The current version of the pretty printers are not python3 compatible,
so turn them off by default until sufficiently improved.
Reviewers: MaskRay, tamur
Subscribers: mgorny, christof, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D68477
llvm-svn: 373796
The first commit removed the workaround in a old script.
This patch removes it in the file actually used by the bots.
I have no idea if this is still needed, but removing the
workaround seems like the easiest way to test.
I'll revert this change if the bots go red.
llvm-svn: 373653
I have no idea if this is still needed, but removing the
workaround seems like the easiest way to test.
I'll revert this change if the bots go red.
llvm-svn: 373650
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
In both Python 2 and Python 3, gdb.Value.string returns a 'str'. We just
need to delete a `encode("utf-8")` which would return a 'bytes' in
Python 3.
llvm-svn: 373570
This commit follows the trend of doing things per-target instead of
modifying the C++ flags globally. It does so for visibility-related
flags, other basic build flags and Windows-specific flags.
llvm-svn: 373517
This is part of a larger shift to move to per-target settings and
eradicate global variables from the CMake build. I'm starting small
with warnings only because those are easy to transition over and I
want to see how it pans out, but we can handle all flags like exceptions
and RTTI in the future.
llvm-svn: 373511
It turns out the benchmarks need to link against those libraries
explicitly too, so CMake's propagation of PUBLIC dependencies is
used.
llvm-svn: 373506
Summary:
I haven't managed a small reproduction for this bug, it involves
complicated and deeply nested data structures with a wide variety
of pretty printers. But in general, we shouldn't be combining
gdb's command line interface (via gdb.execute) with pretty-printers.
Subscribers: christof, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D68306
llvm-svn: 373402
In reality, this workaround is for the fact that LIBCXX_CXX_ABI=libcxxabi
can't be specified on Linux, since libc++abi isn't shipped with the system.
Since the build bots explicitly specify LIBCXX_CXX_ABI=libcxxabi, they fail
unless we apply the workaround.
llvm-svn: 373385
I tried applying D63883 three times and could never get around to
making it work. I'm giving up on that for now, but soon this should
be irrelevant anyway since all builds will move to the monorepo
(where we're always using the in-tree libc++abi unless explicitly
specified otherwise).
llvm-svn: 373384
Summary:
LWG 3158 marks the allocator_arg_t constructor of std::tuple as
conditionnally explicit based on whether the default constructors
of the tuple's members are explicitly default constructible.
This was previously committed as r372778 and reverted in r372832 due to
the commit breaking LLVM's build in C++14 mode. This issue has now been
addressed.
Reviewers: mclow.lists
Subscribers: christof, jkorous, dexonsmith, libcxx-commits
Tags: #libc
Differential Revision: https://reviews.llvm.org/D65232
llvm-svn: 373092
Summary:
LWG2510 makes tag types like allocator_arg_t explicitly default
constructible instead of implicitly default constructible. It also
makes the constructors for std::pair and std::tuple conditionally
explicit based on the explicit-ness of the default constructibility
for the pair/tuple's elements.
This was previously committed as r372777 and reverted in r372832 due to
the commit breaking LLVM's build in C++14 mode. This issue has now been
addressed.
Reviewers: mclow.lists
Subscribers: christof, jkorous, dexonsmith, libcxx-commits
Tags: #libc
Differential Revision: https://reviews.llvm.org/D65161
llvm-svn: 372983
Users should only get the assert() macros if they explicitly include
them.
Found after switching from the GNU C++ stdlib to the LLVM C++ stdlib.
llvm-svn: 372963
We don't support GCC 4 and older according to the documentation, so
we should pretend it doesn't exist.
This is a re-application of r372787.
llvm-svn: 372916
This declaration was previously missing despite appearing in the
synopsis. Users are still required to include <ostream> to get the
definition of the streaming operator.
llvm-svn: 372909
This also reverts:
- r372778: [libc++] Implement LWG 3158
- r372782: [libc++] Try fixing tests that fail on GCC 5 and older
- r372787: Purge mentions of GCC 4 from the test suite
Reason: the change breaks compilation of LLVM with libc++, for details see
http://lists.llvm.org/pipermail/libcxx-dev/2019-September/000599.html
llvm-svn: 372832
Summary: As suggested by @ldionne in D66178, this patch removes C++03 variadics //only//. Following patches will apply more updates.
Reviewers: ldionne, EricWF, mclow.lists
Subscribers: christof, dexonsmith, libcxx-commits, ldionne
Tags: #libc
Differential Revision: https://reviews.llvm.org/D67675
llvm-svn: 372780
Summary:
LWG 3158 marks the allocator_arg_t constructor of std::tuple as
conditionnally explicit based on whether the default constructors
of the tuple's members are explicitly default constructible.
Reviewers: EricWF, mclow.lists
Subscribers: christof, jkorous, dexonsmith, libcxx-commits
Tags: #libc
Differential Revision: https://reviews.llvm.org/D65232
llvm-svn: 372778
Summary:
LWG2510 makes tag types like allocator_arg_t explicitly default
constructible instead of implicitly default constructible. It also
makes the constructors for std::pair and std::tuple conditionally
explicit based on the explicit-ness of the default constructibility
for the pair/tuple's elements.
Reviewers: mclow.lists, EricWF
Subscribers: christof, jkorous, dexonsmith, libcxx-commits
Tags: #libc
Differential Revision: https://reviews.llvm.org/D65161
llvm-svn: 372777
std::condition_variable is currently implemented via
pthread_cond_timedwait() on systems that use pthread. This is
problematic, since that function waits by default on CLOCK_REALTIME
and libc++ does not provide any mechanism to change from this
default.
Due to this, regardless of if condition_variable::wait_until() is
called with a chrono::system_clock or chrono::steady_clock parameter,
condition_variable::wait_until() will wait using CLOCK_REALTIME. This
is not accurate to the C++ standard as calling
condition_variable::wait_until() with a chrono::steady_clock parameter
should use CLOCK_MONOTONIC.
This is particularly problematic because CLOCK_REALTIME is a bad
choice as it is subject to discontinuous time adjustments, that may
cause condition_variable::wait_until() to immediately timeout or wait
indefinitely.
This change fixes this issue with a new POSIX function,
pthread_cond_clockwait() proposed on
http://austingroupbugs.net/view.php?id=1216. The new function is
similar to pthread_cond_timedwait() with the addition of a clock
parameter that allows it to wait using either CLOCK_REALTIME or
CLOCK_MONOTONIC, thus allowing condition_variable::wait_until() to
wait using CLOCK_REALTIME for chrono::system_clock and CLOCK_MONOTONIC
for chrono::steady_clock.
pthread_cond_clockwait() is implemented in glibc (2.30 and later) and
Android's bionic (Android API version 30 and later).
This change additionally makes wait_for() and wait_until() with clocks
other than chrono::system_clock use CLOCK_MONOTONIC.<Paste>
llvm-svn: 372016
exceptions are disabled.
The patch was reverted due to some confusion about non-movable types. ie
types
that explicitly delete their move constructors. However, such types do
not meet
the requirement for `MoveConstructible`, which is required by
`std::vector`:
Summary:
`std::vector<T>` is free choose between using copy or move operations
when it
needs to resize. The standard only candidates that the correct exception
safety
guarantees are provided. When exceptions are disabled these guarantees
are
trivially satisfied. Meaning vector is free to optimize it's
implementation by
moving instead of copying.
This patch makes `std::vector` unconditionally move elements when
exceptions are
disabled. This optimization is conforming according to the current
standard wording.
There are concerns that moving in `-fno-noexceptions`mode will be a
surprise to
users. For example, a user may be surprised to find their code is slower
with
exceptions enabled than it is disabled. I'm sympathetic to this
surprised, but
I don't think it should block this optimization.
Reviewers: mclow.lists, ldionne, rsmith
Reviewed By: ldionne
Subscribers: zoecarver, christof, dexonsmith, libcxx-commits
Tags: #libc
Differential Revision: https://reviews.llvm.org/D62228
llvm-svn: 371867
Summary:
In https://svnweb.freebsd.org/changeset/base/351659 @emaste removed gets() from
FreeBSD 13's libc, and our copies of libc++ and libstdc++. In that change, the
declarations were simply deleted, but I would like to propose this conditional
test instead.
Reviewers: EricWF, mclow.lists, emaste
Reviewed By: mclow.lists
Subscribers: krytarowski, christof, ldionne, emaste, libcxx-commits
Differential Revision: https://reviews.llvm.org/D67316
llvm-svn: 371324
Summary:
This patch is an exact duplicate of https://reviews.llvm.org/D65609, except
that it uses the newly introduced testing framework to detect if gdb is present
so that the tests won't fail on machines without gdb.
Reviewers: echristo, EricWF
Subscribers: christof, ldionne, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D67238
llvm-svn: 371131
Louis Dionne