This gets rid of the memory fence in the hot path (dereferencing the
ManagedStatic), trading for an extra mutex lock in the cold path (when
the ManagedStatic was uninitialized). Since this only happens on the
first accesses it shouldn't matter much. On strict architectures like
x86 this removes any atomic instructions from the hot path.
Also remove the tsan annotations, tsan knows how standard atomics work
so they should be unnecessary now.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@274131 91177308-0d34-0410-b5e6-96231b3b80d8
CALL_ONCE_... macro in the legacy pass manager with the new
llvm::call_once facility.
Nothing changed sicne the last attempt in r271781 which I reverted in
r271788. At least one of the failures I saw was spurious, and I want to
make sure the other failures are real before I work around them -- they
appeared to only effect ppc64le and ppc64be.
Original commit message of r271781:
----
[LPM] Reinstate r271652 to replace the CALL_ONCE_... macro in the legacy
pass manager with the new llvm::call_once facility.
This reverts commit r271657 and re-applies r271652 with a fix to
actually work with arguments. In the original version, we just ended up
directly calling std::call_once via ADL because of the std::once_flag
argument. The llvm::call_once never worked with arguments. Now,
llvm::call_once is a variadic template that perfectly forwards
everything. As a part of this it had to move to the header and we use
a generic functor rather than an explict function pointer. It would be
nice to use std::invoke here but we don't have it yet. That means
pointer to members won't work here, but that seems a tolerable
compromise.
I've also tested this by forcing the fallback path, so hopefully it
sticks this time.
----
Original commit message of r271652:
----
[LPM] Replace the CALL_ONCE_... macro in the legacy pass manager with
the new llvm::call_once facility.
This facility matches the standard APIs and when the platform supports
it actually directly uses the standard provided functionality. This is
both more efficient on some platforms and much more TSan friendly.
The only remaining user of the cas_flag and home-rolled atomics is the
fallback implementation of call_once. I have a patch that removes them
entirely, but it needs a Windows patch to land first.
This alone substantially cleans up the macros for the legacy pass
manager, and should subsume some of the work Mehdi was doing to clear
the path for TSan testing of ThinLTO, a really important step to have
reliable upstream testing of ThinLTO in all forms.
----
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@271800 91177308-0d34-0410-b5e6-96231b3b80d8
There appears to be a strange exception thrown and crash using call_once
on a PPC build bot, and a *really* weird windows link error for
GCMetadata.obj. Still need to investigate the cause of both problems.
Original change summary:
[LPM] Reinstate r271652 to replace the CALL_ONCE_... macro in the legacy
pass manager with the new llvm::call_once facility.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@271788 91177308-0d34-0410-b5e6-96231b3b80d8
pass manager with the new llvm::call_once facility.
This reverts commit r271657 and re-applies r271652 with a fix to
actually work with arguments. In the original version, we just ended up
directly calling std::call_once via ADL because of the std::once_flag
argument. The llvm::call_once never worked with arguments. Now,
llvm::call_once is a variadic template that perfectly forwards
everything. As a part of this it had to move to the header and we use
a generic functor rather than an explict function pointer. It would be
nice to use std::invoke here but we don't have it yet. That means
pointer to members won't work here, but that seems a tolerable
compromise.
I've also tested this by forcing the fallback path, so hopefully it
sticks this time.
Original commit message:
----
[LPM] Replace the CALL_ONCE_... macro in the legacy pass manager with
the new llvm::call_once facility.
This facility matches the standard APIs and when the platform supports
it actually directly uses the standard provided functionality. This is
both more efficient on some platforms and much more TSan friendly.
The only remaining user of the cas_flag and home-rolled atomics is the
fallback implementation of call_once. I have a patch that removes them
entirely, but it needs a Windows patch to land first.
This alone substantially cleans up the macros for the legacy pass
manager, and should subsume some of the work Mehdi was doing to clear
the path for TSan testing of ThinLTO, a really important step to have
reliable upstream testing of ThinLTO in all forms.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@271781 91177308-0d34-0410-b5e6-96231b3b80d8
D19271.
Previous attempt was broken by NetBSD, so in this version I've made the
fallback path generic rather than Windows specific and sent both Windows
and NetBSD to it.
I've also re-formatted the code some, and used an exact clone of the
code in PassSupport.h for doing manual call-once using our atomics
rather than rolling a new one.
If this sticks, we can replace the fallback path for Windows with
a Windows-specific implementation that is more reliable.
Original commit message:
This patch adds an llvm_call_once which is a wrapper around
std::call_once on platforms where it is available and devoid
of bugs. The patch also migrates the ManagedStatic mutex to
be allocated using llvm_call_once.
These changes are philosophically equivalent to the changes
added in r219638, which were reverted due to a hang on Win32
which was the result of a bug in the Windows implementation
of std::call_once.
Differential Revision: http://reviews.llvm.org/D5922
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@271558 91177308-0d34-0410-b5e6-96231b3b80d8
This reverts commit r269577.
Broke NetBSD, waiting for Kamil to investigate
From: Mehdi Amini <mehdi.amini@apple.com>
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@269584 91177308-0d34-0410-b5e6-96231b3b80d8
This reverts commit r221331 and reinstate r220932 as discussed in D19271.
Original commit message was:
This patch adds an llvm_call_once which is a wrapper around
std::call_once on platforms where it is available and devoid
of bugs. The patch also migrates the ManagedStatic mutex to
be allocated using llvm_call_once.
These changes are philosophically equivalent to the changes
added in r219638, which were reverted due to a hang on Win32
which was the result of a bug in the Windows implementation
of std::call_once.
Differential Revision: http://reviews.llvm.org/D5922
From: Mehdi Amini <mehdi.amini@apple.com>
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@269577 91177308-0d34-0410-b5e6-96231b3b80d8
Remove support for Valgrind-based TSan, which hasn't been maintained for a
few years. We now use the TSan annotations only if LLVM is compiled with
-fsanitize=thread. We no longer need the weak function definitions as we
are guaranteed that our program is linked directly with the TSan runtime.
Differential Revision: http://reviews.llvm.org/D12121
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@245374 91177308-0d34-0410-b5e6-96231b3b80d8
Commit 220932 caused crash when building clang-tblgen on aarch64 debian target,
so it's blocking all daily tests.
The std::call_once implementation in pthread has bug for aarch64 debian.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221331 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
This patch adds an llvm_call_once which is a wrapper around std::call_once on platforms where it is available and devoid of bugs. The patch also migrates the ManagedStatic mutex to be allocated using llvm_call_once.
These changes are philosophically equivalent to the changes added in r219638, which were reverted due to a hang on Win32 which was the result of a bug in the Windows implementation of std::call_once.
Reviewers: aaron.ballman, chapuni, chandlerc, rnk
Reviewed By: rnk
Subscribers: majnemer, llvm-commits
Differential Revision: http://reviews.llvm.org/D5922
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220932 91177308-0d34-0410-b5e6-96231b3b80d8
This patch adds a new llvm_call_once function which is used by the ManagedStatic implementation to safely initialize a global to avoid static construction and destruction.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@219638 91177308-0d34-0410-b5e6-96231b3b80d8
std::recursive_mutex are not available on MinGW and breaks the
builder. Revert to using a function local static and sys::Mutex
just to get the tree green until we figure out a better solution.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211424 91177308-0d34-0410-b5e6-96231b3b80d8
This patch removes the LLVM global lock, and updates all existing
users of the global lock to use their own mutex. None of the
existing users of the global lock were protecting code that was
mutually exclusive with any of the other users of the global
lock, so its purpose was not being met.
Reviewed by: rnk
Differential Revision: http://reviews.llvm.org/D4142
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211277 91177308-0d34-0410-b5e6-96231b3b80d8
This patch removes the functions llvm_start_multithreaded() and
llvm_stop_multithreaded(), and changes llvm_is_multithreaded()
to return a constant value based on the value of the compile-time
definition LLVM_ENABLE_THREADS.
Previously, it was possible to have compile-time support for
threads on, and runtime support for threads off, in which case
certain mutexes were not allocated or ever acquired. Now, if the
build is created with threads enabled, mutexes are always acquired.
A test before/after patch of compiling a very large TU showed no
noticeable performance impact of this change.
Reviewers: rnk
Differential Revision: http://reviews.llvm.org/D4076
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@210600 91177308-0d34-0410-b5e6-96231b3b80d8
Breaks the MSVC build.
DataStream.cpp(44): error C2552: 'llvm::Statistic::Value' : non-aggregates cannot be initialized with initializer list
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@202731 91177308-0d34-0410-b5e6-96231b3b80d8
With C++11 we finally have a standardized way to specify atomic operations. Use
them to replace the existing custom implemention. Sadly the translation is not
entirely trivial as std::atomic allows more fine-grained control over the
atomicity. I tried to preserve the old semantics as well as possible.
Differential Revision: http://llvm-reviews.chandlerc.com/D2915
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@202730 91177308-0d34-0410-b5e6-96231b3b80d8
These annotations are disabled entirely when either ENABLE_THREADS is off, or
building a release build. When enabled, they add calls to functions with no
statements to ManagedStatic's getters.
Use these annotations to inform tsan that the race used inside ManagedStatic
initialization is actually benign. Thanks to Kostya Serebryany for helping
write this patch!
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@144567 91177308-0d34-0410-b5e6-96231b3b80d8
