[llvm] r211287 - Remove support for LLVM runtime multi-threading.
Zachary Turner
zturner at google.com
Fri Jun 20 10:38:44 PDT 2014
Thanks. I'll try with these options as well. I have a pretty beefy
machine, so a full build only takes 2 or 3 minutes for me, let's see if I
can repro...
On Fri, Jun 20, 2014 at 10:36 AM, Yaron Keren <yaron.keren at gmail.com> wrote:
> I use a bunch more
>
> cmake -G "Visual Studio 12" -DLLVM_TARGETS_TO_BUILD=X86
> -DLLVM_ENABLE_ASSERTIONS=ON -DLLVM_INCLUDE_EXAMPLES=OFF
> -DLLVM_INCLUDE_DOCS=OFF -DLLVM_USE_CRT_RELWITHDEBINFO:STRING=MT
> -DLLVM_ENABLE_THREADS:BOOL=OFF ..
>
> and build in Release with Debug Info and with asserts.
>
> I'm still looking into this, rebuilding takes time.
>
> Yaron
>
>
>
> 2014-06-20 20:26 GMT+03:00 Zachary Turner <zturner at google.com>:
>
> It's odd that I'm not able to reproduce this. I'm also using MSVC and I
>> run cmake as
>>
>> cmake -D LLVM_ENABLE_THREADS:BOOL=OFF
>>
>> Is this what you're doing, or do you have some other options set?
>>
>
>
> On Fri, Jun 20, 2014 at 10:04 AM, Yaron Keren <yaron.keren at gmail.com>
> wrote:
>
>> No, I had not verified this yet, just hoped it may ring a bell.
>> I'll try revisions.
>>
>> Yaron
>>
>>
>>
>> 2014-06-20 19:54 GMT+03:00 Zachary Turner <zturner at google.com>:
>>
>> I am trying to reproduce locally as well.
>>
>>
>>
>> On Fri, Jun 20, 2014 at 9:52 AM, Zachary Turner <zturner at google.com>
>> wrote:
>>
>>> Did you verify that it's this revision specifically that caused it? Can
>>> you just checkout the revision immediately before this and confirm it
>>> works, and then checkout this revision and confirm it doesn't work? I
>>> suspect it's actually a different revision that caused it, since these
>>> functions were actually just no-ops at this point.
>>>
>>>
>>> On Fri, Jun 20, 2014 at 9:46 AM, Yaron Keren <yaron.keren at gmail.com>
>>> wrote:
>>>
>>>> Running ARCMT clang tests with these two tools stopped working for me
>>>> after updating to trunk today, on WIndows 64 bit Visual C++ 2013 building
>>>> 32 bit target. They just hang and never finish. I thought initially that's
>>>> related to them running in thread but the same happens even if the thread
>>>> is disabled in main() and cindextest_main() is called directly.
>>>> llvm tests complete OK as are other clang tests that do not use c-arcmt-test
>>>> and and c-index-test.
>>>>
>>>> It this possibly related to mutex changes?
>>>> Maybe LLVM must be built with threads to support the ARCMT tests?
>>>>
>>>> Yaron
>>>>
>>>>
>>>>
>>>>
>>>> 2014-06-20 19:40 GMT+03:00 Zachary Turner <zturner at google.com>:
>>>>
>>>> It should continue to work. The only thing llvm_start_multithreaded()
>>>>> and llvm_stop_multithreaded() did before, despite their names, was to
>>>>> allocate a mutex on the heap that served as a global lock. In other words,
>>>>> it didn't really do much of anything useful. You could still create
>>>>> threads even if you compiled with LLVM_ENABLE_THREADS=0. Some stuff might
>>>>> not have been safe for concurrent access, but a) that's not an issue with
>>>>> these tests anyway, since they create the thread and then join, so there is
>>>>> no concurrency, and b) the areas that were conditionally protected by this
>>>>> global lock before are now always protected.
>>>>>
>>>>> In fact, this makes me wonder if we even need the compile time flag.
>>>>>
>>>>
>>>>
>>>> On Fri, Jun 20, 2014 at 9:34 AM, Yaron Keren <yaron.keren at gmail.com>
>>>> wrote:
>>>>
>>>>> Hi,
>>>>>
>>>>> Two of the clang test tools, c-arcmt-test and and c-index-test always
>>>>> run the test through one thread only:
>>>>>
>>>>> /* We intentionally run in a separate thread to ensure we at least
>>>>> minimal
>>>>> * testing of a multithreaded environment (for example, having a
>>>>> reduced stack
>>>>> * size). */
>>>>>
>>>>> If LLVM/clang were built without thread support, can these tools
>>>>> continue the same?
>>>>>
>>>>> Yaron
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> 2014-06-19 21:18 GMT+03:00 Zachary Turner <zturner at google.com>:
>>>>>
>>>>>> Author: zturner
>>>>>> Date: Thu Jun 19 13:18:23 2014
>>>>>> New Revision: 211287
>>>>>>
>>>>>> URL: http://llvm.org/viewvc/llvm-project?rev=211287&view=rev
>>>>>> Log:
>>>>>> Remove support for LLVM runtime multi-threading.
>>>>>>
>>>>>> After a number of previous small iterations, the functions
>>>>>> llvm_start_multithreaded() and llvm_stop_multithreaded() have
>>>>>> been reduced essentially to no-ops. This change removes them
>>>>>> entirely.
>>>>>>
>>>>>> Reviewed by: rnk, dblaikie
>>>>>>
>>>>>> Differential Revision: http://reviews.llvm.org/D4216
>>>>>>
>>>>>> Modified:
>>>>>> llvm/trunk/docs/ProgrammersManual.rst
>>>>>> llvm/trunk/include/llvm-c/Core.h
>>>>>> llvm/trunk/include/llvm/Support/ManagedStatic.h
>>>>>> llvm/trunk/include/llvm/Support/Threading.h
>>>>>> llvm/trunk/lib/IR/Core.cpp
>>>>>> llvm/trunk/lib/Support/Threading.cpp
>>>>>> llvm/trunk/unittests/Support/ManagedStatic.cpp
>>>>>>
>>>>>> Modified: llvm/trunk/docs/ProgrammersManual.rst
>>>>>> URL:
>>>>>> http://llvm.org/viewvc/llvm-project/llvm/trunk/docs/ProgrammersManual.rst?rev=211287&r1=211286&r2=211287&view=diff
>>>>>>
>>>>>> ==============================================================================
>>>>>> --- llvm/trunk/docs/ProgrammersManual.rst (original)
>>>>>> +++ llvm/trunk/docs/ProgrammersManual.rst Thu Jun 19 13:18:23 2014
>>>>>> @@ -2170,46 +2170,13 @@ compiler, consider compiling LLVM and LL
>>>>>> using the resultant compiler to build a copy of LLVM with
>>>>>> multithreading
>>>>>> support.
>>>>>>
>>>>>> -.. _startmultithreaded:
>>>>>> -
>>>>>> -Entering and Exiting Multithreaded Mode
>>>>>> ----------------------------------------
>>>>>> -
>>>>>> -In order to properly protect its internal data structures while
>>>>>> avoiding
>>>>>> -excessive locking overhead in the single-threaded case, the LLVM
>>>>>> must intialize
>>>>>> -certain data structures necessary to provide guards around its
>>>>>> internals. To do
>>>>>> -so, the client program must invoke ``llvm_start_multithreaded()``
>>>>>> before making
>>>>>> -any concurrent LLVM API calls. To subsequently tear down these
>>>>>> structures, use
>>>>>> -the ``llvm_stop_multithreaded()`` call. You can also use the
>>>>>> -``llvm_is_multithreaded()`` call to check the status of
>>>>>> multithreaded mode.
>>>>>> -
>>>>>> -Note that both of these calls must be made *in isolation*. That is
>>>>>> to say that
>>>>>> -no other LLVM API calls may be executing at any time during the
>>>>>> execution of
>>>>>> -``llvm_start_multithreaded()`` or ``llvm_stop_multithreaded``. It
>>>>>> is the
>>>>>> -client's responsibility to enforce this isolation.
>>>>>> -
>>>>>> -The return value of ``llvm_start_multithreaded()`` indicates the
>>>>>> success or
>>>>>> -failure of the initialization. Failure typically indicates that
>>>>>> your copy of
>>>>>> -LLVM was built without multithreading support, typically because GCC
>>>>>> atomic
>>>>>> -intrinsics were not found in your system compiler. In this case,
>>>>>> the LLVM API
>>>>>> -will not be safe for concurrent calls. However, it *will* be safe
>>>>>> for hosting
>>>>>> -threaded applications in the JIT, though :ref:`care must be taken
>>>>>> -<jitthreading>` to ensure that side exits and the like do not
>>>>>> accidentally
>>>>>> -result in concurrent LLVM API calls.
>>>>>> -
>>>>>> .. _shutdown:
>>>>>>
>>>>>> Ending Execution with ``llvm_shutdown()``
>>>>>> -----------------------------------------
>>>>>>
>>>>>> When you are done using the LLVM APIs, you should call
>>>>>> ``llvm_shutdown()`` to
>>>>>> -deallocate memory used for internal structures. This will also
>>>>>> invoke
>>>>>> -``llvm_stop_multithreaded()`` if LLVM is operating in multithreaded
>>>>>> mode. As
>>>>>> -such, ``llvm_shutdown()`` requires the same isolation guarantees as
>>>>>> -``llvm_stop_multithreaded()``.
>>>>>> -
>>>>>> -Note that, if you use scope-based shutdown, you can use the
>>>>>> -``llvm_shutdown_obj`` class, which calls ``llvm_shutdown()`` in its
>>>>>> destructor.
>>>>>> +deallocate memory used for internal structures.
>>>>>>
>>>>>> .. _managedstatic:
>>>>>>
>>>>>> @@ -2217,15 +2184,11 @@ Lazy Initialization with ``ManagedStatic
>>>>>> ------------------------------------------
>>>>>>
>>>>>> ``ManagedStatic`` is a utility class in LLVM used to implement static
>>>>>> -initialization of static resources, such as the global type tables.
>>>>>> Before the
>>>>>> -invocation of ``llvm_shutdown()``, it implements a simple lazy
>>>>>> initialization
>>>>>> -scheme. Once ``llvm_start_multithreaded()`` returns, however, it
>>>>>> uses
>>>>>> +initialization of static resources, such as the global type tables.
>>>>>> In a
>>>>>> +single-threaded environment, it implements a simple lazy
>>>>>> initialization scheme.
>>>>>> +When LLVM is compiled with support for multi-threading, however, it
>>>>>> uses
>>>>>> double-checked locking to implement thread-safe lazy initialization.
>>>>>>
>>>>>> -Note that, because no other threads are allowed to issue LLVM API
>>>>>> calls before
>>>>>> -``llvm_start_multithreaded()`` returns, it is possible to have
>>>>>> -``ManagedStatic``\ s of ``llvm::sys::Mutex``\ s.
>>>>>> -
>>>>>> .. _llvmcontext:
>>>>>>
>>>>>> Achieving Isolation with ``LLVMContext``
>>>>>>
>>>>>> Modified: llvm/trunk/include/llvm-c/Core.h
>>>>>> URL:
>>>>>> http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm-c/Core.h?rev=211287&r1=211286&r2=211287&view=diff
>>>>>>
>>>>>> ==============================================================================
>>>>>> --- llvm/trunk/include/llvm-c/Core.h (original)
>>>>>> +++ llvm/trunk/include/llvm-c/Core.h Thu Jun 19 13:18:23 2014
>>>>>> @@ -2848,16 +2848,13 @@ void LLVMDisposePassManager(LLVMPassMana
>>>>>> * @{
>>>>>> */
>>>>>>
>>>>>> -/** Allocate and initialize structures needed to make LLVM safe for
>>>>>> - multithreading. The return value indicates whether multithreaded
>>>>>> - initialization succeeded. Must be executed in isolation from all
>>>>>> - other LLVM api calls.
>>>>>> - @see llvm::llvm_start_multithreaded */
>>>>>> +/** Deprecated: Multi-threading can only be enabled/disabled with
>>>>>> the compile
>>>>>> + time define LLVM_ENABLE_THREADS. This function always returns
>>>>>> + LLVMIsMultithreaded(). */
>>>>>> LLVMBool LLVMStartMultithreaded(void);
>>>>>>
>>>>>> -/** Deallocate structures necessary to make LLVM safe for
>>>>>> multithreading.
>>>>>> - Must be executed in isolation from all other LLVM api calls.
>>>>>> - @see llvm::llvm_stop_multithreaded */
>>>>>> +/** Deprecated: Multi-threading can only be enabled/disabled with
>>>>>> the compile
>>>>>> + time define LLVM_ENABLE_THREADS. */
>>>>>> void LLVMStopMultithreaded(void);
>>>>>>
>>>>>> /** Check whether LLVM is executing in thread-safe mode or not.
>>>>>>
>>>>>> Modified: llvm/trunk/include/llvm/Support/ManagedStatic.h
>>>>>> URL:
>>>>>> http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Support/ManagedStatic.h?rev=211287&r1=211286&r2=211287&view=diff
>>>>>>
>>>>>> ==============================================================================
>>>>>> --- llvm/trunk/include/llvm/Support/ManagedStatic.h (original)
>>>>>> +++ llvm/trunk/include/llvm/Support/ManagedStatic.h Thu Jun 19
>>>>>> 13:18:23 2014
>>>>>> @@ -103,9 +103,6 @@ void llvm_shutdown();
>>>>>> /// llvm_shutdown() when it is destroyed.
>>>>>> struct llvm_shutdown_obj {
>>>>>> llvm_shutdown_obj() { }
>>>>>> - explicit llvm_shutdown_obj(bool multithreaded) {
>>>>>> - if (multithreaded) llvm_start_multithreaded();
>>>>>> - }
>>>>>> ~llvm_shutdown_obj() { llvm_shutdown(); }
>>>>>> };
>>>>>>
>>>>>>
>>>>>> Modified: llvm/trunk/include/llvm/Support/Threading.h
>>>>>> URL:
>>>>>> http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Support/Threading.h?rev=211287&r1=211286&r2=211287&view=diff
>>>>>>
>>>>>> ==============================================================================
>>>>>> --- llvm/trunk/include/llvm/Support/Threading.h (original)
>>>>>> +++ llvm/trunk/include/llvm/Support/Threading.h Thu Jun 19 13:18:23
>>>>>> 2014
>>>>>> @@ -7,30 +7,19 @@
>>>>>> //
>>>>>>
>>>>>> //===----------------------------------------------------------------------===//
>>>>>> //
>>>>>> -// TThis file defines llvm_start_multithreaded() and friends.
>>>>>> +// This file declares helper functions for running LLVM in a
>>>>>> multi-threaded
>>>>>> +// environment.
>>>>>> //
>>>>>>
>>>>>> //===----------------------------------------------------------------------===//
>>>>>>
>>>>>> #ifndef LLVM_SUPPORT_THREADING_H
>>>>>> #define LLVM_SUPPORT_THREADING_H
>>>>>>
>>>>>> -namespace llvm {
>>>>>> - /// llvm_start_multithreaded - Allocate and initialize structures
>>>>>> needed to
>>>>>> - /// make LLVM safe for multithreading. The return value indicates
>>>>>> whether
>>>>>> - /// multithreaded initialization succeeded. LLVM will still be
>>>>>> operational
>>>>>> - /// on "failed" return, and will still be safe for hosting
>>>>>> threading
>>>>>> - /// applications in the JIT, but will not be safe for concurrent
>>>>>> calls to the
>>>>>> - /// LLVM APIs.
>>>>>> - /// THIS MUST EXECUTE IN ISOLATION FROM ALL OTHER LLVM API CALLS.
>>>>>> - bool llvm_start_multithreaded();
>>>>>> -
>>>>>> - /// llvm_stop_multithreaded - Deallocate structures necessary to
>>>>>> make LLVM
>>>>>> - /// safe for multithreading.
>>>>>> - /// THIS MUST EXECUTE IN ISOLATION FROM ALL OTHER LLVM API CALLS.
>>>>>> - void llvm_stop_multithreaded();
>>>>>> +#include "llvm/Support/Mutex.h"
>>>>>>
>>>>>> - /// llvm_is_multithreaded - Check whether LLVM is executing in
>>>>>> thread-safe
>>>>>> - /// mode or not.
>>>>>> +namespace llvm {
>>>>>> + /// Returns true if LLVM is compiled with support for
>>>>>> multi-threading, and
>>>>>> + /// false otherwise.
>>>>>> bool llvm_is_multithreaded();
>>>>>>
>>>>>> /// llvm_execute_on_thread - Execute the given \p UserFn on a
>>>>>> separate
>>>>>>
>>>>>> Modified: llvm/trunk/lib/IR/Core.cpp
>>>>>> URL:
>>>>>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/IR/Core.cpp?rev=211287&r1=211286&r2=211287&view=diff
>>>>>>
>>>>>> ==============================================================================
>>>>>> --- llvm/trunk/lib/IR/Core.cpp (original)
>>>>>> +++ llvm/trunk/lib/IR/Core.cpp Thu Jun 19 13:18:23 2014
>>>>>> @@ -2702,11 +2702,10 @@ void LLVMDisposePassManager(LLVMPassMana
>>>>>> /*===-- Threading
>>>>>> ------------------------------------------------------===*/
>>>>>>
>>>>>> LLVMBool LLVMStartMultithreaded() {
>>>>>> - return llvm_start_multithreaded();
>>>>>> + return LLVMIsMultithreaded();
>>>>>> }
>>>>>>
>>>>>> void LLVMStopMultithreaded() {
>>>>>> - llvm_stop_multithreaded();
>>>>>> }
>>>>>>
>>>>>> LLVMBool LLVMIsMultithreaded() {
>>>>>>
>>>>>> Modified: llvm/trunk/lib/Support/Threading.cpp
>>>>>> URL:
>>>>>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Support/Threading.cpp?rev=211287&r1=211286&r2=211287&view=diff
>>>>>>
>>>>>> ==============================================================================
>>>>>> --- llvm/trunk/lib/Support/Threading.cpp (original)
>>>>>> +++ llvm/trunk/lib/Support/Threading.cpp Thu Jun 19 13:18:23 2014
>>>>>> @@ -7,7 +7,8 @@
>>>>>> //
>>>>>>
>>>>>> //===----------------------------------------------------------------------===//
>>>>>> //
>>>>>> -// This file implements llvm_start_multithreaded() and friends.
>>>>>> +// This file defines helper functions for running LLVM in a
>>>>>> multi-threaded
>>>>>> +// environment.
>>>>>> //
>>>>>>
>>>>>> //===----------------------------------------------------------------------===//
>>>>>>
>>>>>> @@ -19,38 +20,14 @@
>>>>>>
>>>>>> using namespace llvm;
>>>>>>
>>>>>> -static bool multithreaded_mode = false;
>>>>>> -
>>>>>> -bool llvm::llvm_start_multithreaded() {
>>>>>> +bool llvm::llvm_is_multithreaded() {
>>>>>> #if LLVM_ENABLE_THREADS != 0
>>>>>> - assert(!multithreaded_mode && "Already multithreaded!");
>>>>>> - multithreaded_mode = true;
>>>>>> -
>>>>>> - // We fence here to ensure that all initialization is complete
>>>>>> BEFORE we
>>>>>> - // return from llvm_start_multithreaded().
>>>>>> - sys::MemoryFence();
>>>>>> return true;
>>>>>> #else
>>>>>> return false;
>>>>>> #endif
>>>>>> }
>>>>>>
>>>>>> -void llvm::llvm_stop_multithreaded() {
>>>>>> -#if LLVM_ENABLE_THREADS != 0
>>>>>> - assert(multithreaded_mode && "Not currently multithreaded!");
>>>>>> -
>>>>>> - // We fence here to insure that all threaded operations are
>>>>>> complete BEFORE we
>>>>>> - // return from llvm_stop_multithreaded().
>>>>>> - sys::MemoryFence();
>>>>>> -
>>>>>> - multithreaded_mode = false;
>>>>>> -#endif
>>>>>> -}
>>>>>> -
>>>>>> -bool llvm::llvm_is_multithreaded() {
>>>>>> - return multithreaded_mode;
>>>>>> -}
>>>>>> -
>>>>>> #if LLVM_ENABLE_THREADS != 0 && defined(HAVE_PTHREAD_H)
>>>>>> #include <pthread.h>
>>>>>>
>>>>>>
>>>>>> Modified: llvm/trunk/unittests/Support/ManagedStatic.cpp
>>>>>> URL:
>>>>>> http://llvm.org/viewvc/llvm-project/llvm/trunk/unittests/Support/ManagedStatic.cpp?rev=211287&r1=211286&r2=211287&view=diff
>>>>>>
>>>>>> ==============================================================================
>>>>>> --- llvm/trunk/unittests/Support/ManagedStatic.cpp (original)
>>>>>> +++ llvm/trunk/unittests/Support/ManagedStatic.cpp Thu Jun 19
>>>>>> 13:18:23 2014
>>>>>> @@ -47,7 +47,6 @@ TEST(Initialize, MultipleThreads) {
>>>>>> void *p1 = test1::allocate_stack(a1);
>>>>>> void *p2 = test1::allocate_stack(a2);
>>>>>>
>>>>>> - llvm_start_multithreaded();
>>>>>> pthread_t t1, t2;
>>>>>> pthread_create(&t1, &a1, test1::helper, nullptr);
>>>>>> pthread_create(&t2, &a2, test1::helper, nullptr);
>>>>>> @@ -55,7 +54,6 @@ TEST(Initialize, MultipleThreads) {
>>>>>> pthread_join(t2, nullptr);
>>>>>> free(p1);
>>>>>> free(p2);
>>>>>> - llvm_stop_multithreaded();
>>>>>> }
>>>>>> #endif
>>>>>>
>>>>>>
>>>>>>
>>>>>> _______________________________________________
>>>>>> llvm-commits mailing list
>>>>>> llvm-commits at cs.uiuc.edu
>>>>>> http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
>>>>>>
>>>>>
>>>>>
>>>>
>>>
>>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20140620/47161c25/attachment.html>
More information about the llvm-commits
mailing list