| Commit message (Collapse) | Author | Age | Files | Lines |
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Currently std::mutex has a constexpr constructor, but a non-trivial
destruction.
The constexpr constructor is required to ensure the construction of a
mutex with static storage duration happens at compile time, during
constant initialization, and not during dynamic initialization.
This means that static mutex's are always initialized and can be used
safely during dynamic initialization without the "static initialization
order fiasco".
A trivial destructor is important for similar reasons. If a mutex is
used during dynamic initialization it might also be used during program
termination. If a static mutex has a non-trivial destructor it will be
invoked during termination. This can introduce the "static
deinitialization order fiasco".
Additionally, function-local statics emit a guard variable around
non-trivially destructible types. This results in horrible codegen and
adds a runtime cost to every call to that function. non-local static's
also result in slightly worse codegen but it's not as big of a problem.
Example codegen can be found here: https://goo.gl/3CSzbM
Note: This optimization is not safe with every pthread implementation.
Some implementations allocate on the first call to pthread_mutex_lock
and free the allocation in pthread_mutex_destroy.
Also, changing the triviality of the destructor is not an ABI break.
At least to the best of my knowledge :-)
llvm-svn: 365273
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Thanks to Zoe for the (big, but simple) patch. NFC intended.
llvm-svn: 362252
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Some tests #include <iostream> but they don't use anything from the
header. Those are probably artifacts of when the tests were developped.
llvm-svn: 357181
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Reported on the NetBSD buildbot.
llvm-svn: 353622
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Summary:
Freestanding is *weird*. The standard allows it to differ in a bunch of odd
manners from regular C++, and the committee would like to improve that
situation. I'd like to make libc++ behave better with what freestanding should
be, so that it can be a tool we use in improving the standard. To do that we
need to try stuff out, both with "freestanding the language mode" and
"freestanding the library subset".
Let's start with the super basic: run the libc++ tests in freestanding, using
clang as the compiler, and see what works. The easiest hack to do this:
In utils/libcxx/test/config.py add:
self.cxx.compile_flags += ['-ffreestanding']
Run the tests and they all fail.
Why? Because in freestanding `main` isn't special. This "not special" property
has two effects: main doesn't get mangled, and main isn't allowed to omit its
`return` statement. The first means main gets mangled and the linker can't
create a valid executable for us to test. The second means we spew out warnings
(ew) and the compiler doesn't insert the `return` we omitted, and main just
falls of the end and does whatever undefined behavior (if you're luck, ud2
leading to non-zero return code).
Let's start my work with the basics. This patch changes all libc++ tests to
declare `main` as `int main(int, char**` so it mangles consistently (enabling us
to declare another `extern "C"` main for freestanding which calls the mangled
one), and adds `return 0;` to all places where it was missing. This touches 6124
files, and I apologize.
The former was done with The Magic Of Sed.
The later was done with a (not quite correct but decent) clang tool:
https://gist.github.com/jfbastien/793819ff360baa845483dde81170feed
This works for most tests, though I did have to adjust a few places when e.g.
the test runs with `-x c`, macros are used for main (such as for the filesystem
tests), etc.
Once this is in we can create a freestanding bot which will prevent further
regressions. After that, we can start the real work of supporting C++
freestanding fairly well in libc++.
<rdar://problem/47754795>
Reviewers: ldionne, mclow.lists, EricWF
Subscribers: christof, jkorous, dexonsmith, arphaman, miyuki, libcxx-commits
Differential Revision: https://reviews.llvm.org/D57624
llvm-svn: 353086
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Reported on the NetBSD 8 buildbot.
llvm-svn: 352064
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Reported on the NetBSD 8 buildbot.
llvm-svn: 351995
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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
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llvm-svn: 310155
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On Bionic PTHREAD_MUTEX_INITIALIZER contains the expression "<enum-type> & <integer-type>",
which causes ADL to perform name lookup for operator&. During this lookup Clang decides
that it requires the default member initializer for std::mutex while defining the DMI
for std::mutex::__m_.
If I'm not mistaken this is caused by the explicit noexcept declaration on the defaulted
constructor.
This patch removes the explicit noexcept and instead allows the compiler to declare
the default constructor implicitly noexcept. It also adds a static_assert to ensure
that happens.
Unfortunatly because it's not easy to change the value of _LIBCPP_MUTEX_INITIALIZER
for a single test there is no good way to test this patch.
The Clang behavior causing the trouble here was introduced in r287713, which first
appears in the 4.0 release.
llvm-svn: 304942
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Libc++ is used as a system library on macOS and iOS (amongst others). In order
for users to be able to compile a binary that is intended to be deployed to an
older version of the platform, clang provides the
availability attribute <https://clang.llvm.org/docs/AttributeReference.html#availability>_
that can be placed on declarations to describe the lifecycle of a symbol in the
library.
See docs/DesignDocs/AvailabilityMarkup.rst for more information.
Differential Revision: https://reviews.llvm.org/D31739
llvm-svn: 302172
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This patch overhalls the libc++ test format/configuration in order to fully support modules. By "fully support" I mean get almost all of the tests passing. The main hurdle for doing this is handling tests that `#define _LIBCPP_FOO` macros to test a different configuration. This patch deals with these tests in the following ways:
1. For tests that define single `_LIBCPP_ABI_FOO` macros have been annotated with `// MODULES_DEFINES: _LIBCPP_ABI_FOO`. This allows the test suite to define the macro on the command line so it uses a different set of modules.
2. Tests for libc++'s debug mode (which define custom `_LIBCPP_ASSERT`) are automatically detected by the test suite and are compiled and run with modules disabled.
This patch also cleans up how the `CXXCompiler` helper class handles enabling/disabling language features.
NOTE: This patch uses `LIT` features which were only committed to LLVM today. If this patch breaks running the libc++ tests you probably need to update LLVM.
llvm-svn: 288728
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Some of the mutex tests fail on machines with high load. This patch implements
the test directive "// FLAKY_TEST" which allows a test to be run 3 times
before it's considered a failure.
llvm-svn: 280050
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llvm-svn: 273341
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Quite a few libcxx tests seem to follow the format:
#if _LIBCPP_STD_VER > X
// Do test.
#else
// Empty test.
#endif
We should instead use the UNSUPPORTED lit directive to exclude the test on
earlier C++ standards. This gives us a more accurate number of test passes
for those standards and avoids unnecessary conflicts with other lit
directives on the same tests.
Reviewers: bcraig, ericwf, mclow.lists
Differential revision: http://reviews.llvm.org/D20730
llvm-svn: 271108
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single-threaded mode.
Differential Revision: http://reviews.llvm.org/D14731
llvm-svn: 264191
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tolerances
llvm-svn: 248993
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llvm-svn: 246055
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llvm-svn: 245918
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llvm-svn: 241067
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llvm-svn: 239562
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Summary:
The summary of the bug, provided by Stephan T. Lavavej:
In shared_timed_mutex::try_lock_until() (line 195 in 3.6.0), you need to deliver a notification. The scenario is:
* There are N threads holding the shared lock.
* One thread calls try_lock_until() to attempt to acquire the exclusive lock. It sets the "I want to write" bool/bit, then waits for the N readers to drain away.
* K more threads attempt to acquire the shared lock, but they notice that someone said "I want to write", so they block on a condition_variable.
* At least one of the N readers is stubborn and doesn't release the shared lock.
* The wannabe-writer times out, gives up, and unsets the "I want to write" bool/bit.
At this point, a notification (it needs to be notify_all) must be delivered to the condition_variable that the K wannabe-readers are waiting on. Otherwise, they can block forever without waking up.
Reviewers: mclow.lists, jyasskin
Reviewed By: jyasskin
Subscribers: jyasskin, cfe-commits
Differential Revision: http://reviews.llvm.org/D8796
llvm-svn: 233944
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llvm-svn: 224658
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