Commit Graph

1204 Commits

Author SHA1 Message Date
Jonathan Peyton
6564a70415 [OpenMP][libomp] Fix register constraint for tpause and umwait
Register constraint switched to "=q" which means very specifically (from
https://gcc.gnu.org/onlinedocs/gcc/Machine-Constraints.html#Machine-Constraints)

> Any register accessible as rl. In 32-bit mode, a, b, c, and d; in 64-bit
mode, any integer register.

Older gcc versions (8.x and below) were trying to use esi or edi for the
8 bit flag variable, but it wound up displaying this error in the end:

kmp_lock.cpp: In function ‘void __kmp_spin_backoff(kmp_backoff_t*)’:
kmp_lock.cpp:2684:1: error: unsupported size for integer register
Hence the correct restriction is "=q" instead of "=r".

Fixes: https://github.com/llvm/llvm-project/issues/53309
Differential Revision: https://reviews.llvm.org/D120519
2022-03-07 14:55:49 -06:00
AndreyChurbanov
6d9eb7e7ec [OpenMP] libomp: implemented task priorities.
Before this patch task priorities were ignored, that was a valid implementation
as the task priority is a hint according to OpenMP specification.

Implemented shared list of sorted (high -> low) task deques one per task
priority value. Tasks execution changed to first check if priority tasks ready
for execution exist, and these tasks executed before others;
otherwise usual tasks execution mechanics work.

Differential Revision: https://reviews.llvm.org/D119676
2022-03-07 22:24:18 +03:00
James Beddek
2d0c9b64a0 [OpenMP][CMake] Ensure linking against libm for Linux
Do the same as is done for NetBSD. Some compiler-rt/lib/builtins files call
libm functions (e.g. fmaxl, fabs). Linking libomp with --rtlib=compiler-rt
references these functions.
Downstream report: https://bugs.gentoo.org/816831

Fixes: https://github.com/llvm/llvm-project/issues/51457
2022-03-05 20:20:28 -08:00
AndreyChurbanov
1fbdb03b1d [OpenMP] libomp: omp_in_explicit_task() implemented.
Differential Revision: https://reviews.llvm.org/D120671
2022-03-05 21:46:39 +03:00
Malhar Jajoo
6d658f37a4 [Openmp]: Missing import statement in openmp interface for Fortran
Essentially removed the "use omp_lib_kinds" statement and replaced it
with import to maintain consistency (and avoid compilation error
in case the omp_lib_kinds.mod file is not accessible) in header file.

The import is required to access entities in host scoping unit.

Differential Revision: https://reviews.llvm.org/D120707
2022-03-01 17:33:06 +00:00
Jonathan Peyton
1234011b80 [OpenMP][libomp] Introduce oneAPI compiler support
Introduce KMP_COMPILER_ICX macro to represent compilation with oneAPI
compiler.

Fixup flag detection and compiler ID detection in CMake. Older CMake's
detect IntelLLVM as Clang.

Fix compiler warnings.

Fixup many of the tests to have non-empty parallel regions as they are
elided by oneAPI compiler.
2022-02-14 14:10:33 -06:00
AndreyChurbanov
cb1bee4725 [OpenMP] libomp: fix UB when LIBOMP_NUM_HIDDEN_HELPER_THREADS=1.
The __kmp_hidden_helper_threads_num set to N+1 if user requested N threads.
Thus number of worker hidden helper threads corresponds to user request,
main thread of helper team excluded as it does not participate in actual work.
This also fixes divide-by-0 issue in the code.

Fixes #48656

Differential Revision: https://reviews.llvm.org/D119586
2022-02-12 03:00:38 +03:00
AndreyChurbanov
d84dedc7d3 [OpenMP] libomp: fix bug in implementation of distribute construct.
Fixed mistaken iterations distribution between different target regions.

Differential Revision: https://reviews.llvm.org/D118393
2022-02-11 17:34:26 +03:00
Jonathan Peyton
6be7c21b57 [OpenMP][libomp] Replace accidental VLA with KMP_ALLOCA
MSVC does not support variable length arrays. Replace with KMP_ALLOCA
which is already used in the same file for stack-allocated variables.
2022-02-09 08:09:27 -06:00
Igor Kirillov
4ae885b1e3 [OpenMP] kmp_atomic_float10_max_min.c test should only be executed on x86 platform
Differential Revision: https://reviews.llvm.org/D118988
2022-02-07 10:07:54 +00:00
John Ericson
368c54b81a [openmp][cmake] CMAKE_INSTALL_BINDIR usage should not be quoted
As @mstorsjo wrote in https://reviews.llvm.org/D117945#inline-1132920 :

> This change seems to have broken one aspect: When doing `ninja
install` I now get a warning saying `Error copying file "libomp.dll" to
"libiomp5md.dll".`, and `libiomp5md.dll` isn't installed.
>
> I believe the reason is that the inline cmake snippet is written to
`runtime/src/cmake_install.cmake` and then executed on install, but on
install, `${CMAKE_INSTALL_BINDIR}` isn't set (as `GNUInstallDirs` isn't
included there). Should this maybe expand `${CMAKE_INSTALL_BINDIR}`
right here instead of deferring it to the install cmake, or what's the
right course of action?

I agree that is the right course of action. We also agreed to restore the `CMAKE_INSTALL_PREFIX` that was there before, too.

Reviewed By: mstorsjo

Differential Revision: https://reviews.llvm.org/D118528
2022-01-29 23:52:50 +00:00
Shilei Tian
d4d0ae628c [OpenMP] Fix link error on Windows caused by interop functions
This patch fixes the link error on Windows caused by `interop`
functions.

Reviewed By: mstorsjo

Differential Revision: https://reviews.llvm.org/D118524
2022-01-29 11:29:29 -05:00
Shilei Tian
184f94a8a8 [OpenMP] Fix wrong number in openmp/runtime/src/dllexports
This patch fixes the issue that numbers assigned to `interop` functions were already taken in `openmp/runtime/src/dllexports`.

Reviewed By: jdoerfert

Differential Revision: https://reviews.llvm.org/D118523
2022-01-29 00:23:08 -05:00
Sri Hari Krishna Narayanan
f44e41af41 Runtime for Interop directive
This implements the runtime portion of the interop directive.
It expects the frontend and IRBuilder portions to be in place
for proper execution. It currently works only for GPUs
and has several TODOs that should be addressed going forward.

Reviewed By: RaviNarayanaswamy

Differential Revision: https://reviews.llvm.org/D106674
2022-01-27 15:16:24 -05:00
Malhar Jajoo
c1988dbf2d [openmp] Allow x87 fp functions only in Openmp runtime for x86.
This patch allows Openmp runtime atomic functions operating on x87 high-precision
to be present only in Openmp runtime for x86 architectures

The functions affected are:

__kmpc_atomic_10
__kmpc_atomic_20
__kmpc_atomic_cmplx10_add
__kmpc_atomic_cmplx10_div
__kmpc_atomic_cmplx10_mul
__kmpc_atomic_cmplx10_sub
__kmpc_atomic_float10_add
__kmpc_atomic_float10_div
__kmpc_atomic_float10_mul
__kmpc_atomic_float10_sub

__kmpc_atomic_float10_add_fp
__kmpc_atomic_float10_div_fp
__kmpc_atomic_float10_mul_fp
__kmpc_atomic_float10_sub_fp
__kmpc_atomic_float10_max
__kmpc_atomic_float10_min

Differential Revision: https://reviews.llvm.org/D117473
2022-01-22 22:09:44 +00:00
John Ericson
0a6b4258ab [openmp][cmake] Use GNUInstallDirs to support custom installation dirs
I am breaking apart D99484 so the cause of build failures is easier to
understand.

Differential Revision: https://reviews.llvm.org/D117945
2022-01-22 18:05:36 +00:00
Terry Wilmarth
2e02579a76 [OpenMP] Add use of TPAUSE
Add use of TPAUSE (from WAITPKG) to the runtime for Intel hardware,
with an envirable to turn it on in a particular C-state.  Always uses
TPAUSE if it is selected and enabled by Intel hardware and presence of
WAITPKG, and if not, falls back to old way of checking
__kmp_use_yield, etc.

Differential Revision: https://reviews.llvm.org/D115758
2022-01-18 10:14:32 -06:00
John Ericson
da77db58d7 Revert "[cmake] Use GNUInstallDirs to support custom installation dirs."
https://lab.llvm.org/buildbot/#/builders/46/builds/21146 Still have
this odd error, not sure how to reproduce, so I will just try breaking
up my patch.

This reverts commit 4a678f8072.
2022-01-16 05:48:30 +00:00
John Ericson
4a678f8072 [cmake] Use GNUInstallDirs to support custom installation dirs.
This is the original patch in my GNUInstallDirs series, now last to merge as the final piece!

It arose as a new draft of D28234. I initially did the unorthodox thing of pushing to that when I wasn't the original author, but since I ended up

 - Using `GNUInstallDirs`, rather than mimicking it, as the original author was hesitant to do but others requested.

 - Converting all the packages, not just LLVM, effecting many more projects than LLVM itself.

I figured it was time to make a new revision.

I have used this patch series (and many back-ports) as the basis of https://github.com/NixOS/nixpkgs/pull/111487 for my distro (NixOS), which was merged last spring (2021). It looked like people were generally on board in D28234, but I make note of this here in case extra motivation is useful.

---

As pointed out in the original issue, a central tension is that LLVM already has some partial support for these sorts of things. Variables like `COMPILER_RT_INSTALL_PATH` have already been dealt with. Variables like `LLVM_LIBDIR_SUFFIX` however, will require further work, so that we may use `CMAKE_INSTALL_LIBDIR`.

These remaining items will be addressed in further patches. What is here is now rote and so we should get it out of the way before dealing more intricately with the remainder.

Reviewed By: #libunwind, #libc, #libc_abi, compnerd

Differential Revision: https://reviews.llvm.org/D99484
2022-01-16 05:33:07 +00:00
John Ericson
6e52bfe09d Revert "[cmake] Use GNUInstallDirs to support custom installation dirs."
Sorry for the disruption, I will try again later.

This reverts commit efeb501970.
2022-01-15 07:35:02 +00:00
John Ericson
efeb501970 [cmake] Use GNUInstallDirs to support custom installation dirs.
This is the original patch in my GNUInstallDirs series, now last to merge as the final piece!

It arose as a new draft of D28234. I initially did the unorthodox thing of pushing to that when I wasn't the original author, but since I ended up

 - Using `GNUInstallDirs`, rather than mimicking it, as the original author was hesitant to do but others requested.

 - Converting all the packages, not just LLVM, effecting many more projects than LLVM itself.

I figured it was time to make a new revision.

I have used this patch series (and many back-ports) as the basis of https://github.com/NixOS/nixpkgs/pull/111487 for my distro (NixOS), which was merged last spring (2021). It looked like people were generally on board in D28234, but I make note of this here in case extra motivation is useful.

---

As pointed out in the original issue, a central tension is that LLVM already has some partial support for these sorts of things. Variables like `COMPILER_RT_INSTALL_PATH` have already been dealt with. Variables like `LLVM_LIBDIR_SUFFIX` however, will require further work, so that we may use `CMAKE_INSTALL_LIBDIR`.

These remaining items will be addressed in further patches. What is here is now rote and so we should get it out of the way before dealing more intricately with the remainder.

Reviewed By: #libunwind, #libc, #libc_abi, compnerd

Differential Revision: https://reviews.llvm.org/D99484
2022-01-15 01:08:35 +00:00
Shilei Tian
458db51c10 [OpenMP] Add missing tt_hidden_helper_task_encountered along with tt_found_proxy_tasks
In most cases, hidden helper task behave similar as detached tasks. That means,
for example, if we have to wait for detached tasks, we have to do the same thing
for hidden helper tasks as well. This patch adds the missing condition for hidden
helper task accordingly along with detached task.

Reviewed By: AndreyChurbanov

Differential Revision: https://reviews.llvm.org/D107316
2021-12-29 23:22:53 -05:00
Jonathan Peyton
6a556ecaf4 [OpenMP][libomp] Add use-all syntax to KMP_HW_SUBSET
This patch allows the user to request all resources of a particular
layer (or core-attribute). The syntax of KMP_HW_SUBSET is modified
so the number of units requested is optional or can be replaced with an
'*' character.

e.g., KMP_HW_SUBSET=c:intel_atom@3 will use all the cores after offset 3
e.g., KMP_HW_SUBSET=*c:intel_core will use all the big cores
e.g., KMP_HW_SUBSET=*s,*c,1t will use all the sockets, all cores per
      each socket and 1 thread per core.

Differential Revision: https://reviews.llvm.org/D115826
2021-12-20 13:45:21 -06:00
Jonathan Peyton
9769340905 [OpenMP][libomp] Fix compile errors with new KMP_HW_SUBSET changes
Add missing guards around x86-specific code.

Reviewed By: kaz7

Differential Revision: https://reviews.llvm.org/D115664
2021-12-14 08:33:05 +01:00
John Ericson
ddcc02dbcc Quote some more destination paths with variables
Just defensive CMake-ing. I pulled this from D115544 and D99484 which
are blocked on some lldb CI failures I don't yet understand. Hoping to land
something smaller in the meantime.

Reviewed By: #libc, ldionne

Differential Revision: https://reviews.llvm.org/D115566
2021-12-13 17:29:08 +00:00
Med Ismail Bennani
30fc88bf1d Revert "Revert "Revert "Use GNUInstallDirs to support custom installation dirs. -- LLVM"""
This reverts commit 492de35df4.

I tried to apply John's changes in 8d897ec915 that were expected to
fix his patch but that didn't work unfortunately.

Reverting this again to fix the macOS bots and leave him more time to
investigate the issue.
2021-12-10 17:33:54 -08:00
John Ericson
492de35df4 Revert "Revert "Use GNUInstallDirs to support custom installation dirs. -- LLVM""
This reverts commit 797b50d4be.

See the original D99484. @mib who noticed the original problem could not longer
reproduce it, after I tried and also failed. We are threfore hoping it went
away on its own!

Reviewed By: mib

Differential Revision: https://reviews.llvm.org/D115544
2021-12-10 20:59:43 +00:00
Jonathan Peyton
df20599597 [OpenMP][libomp] Add core attributes to KMP_HW_SUBSET
Allow filtering of resources based on core attributes. There are two new
attributes added:
1) Core Type (intel_atom, intel_core)
2) Core Efficiency (integer) where the higher the efficiency, the more
   performant the core
On hybrid architectures , e.g., Alder Lake, users can specify
KMP_HW_SUBSET=4c:intel_atom,4c:intel_core to select the first four Atom
and first four Big cores. The can also use the efficiency syntax. e.g.,
KMP_HW_SUBSET=2c:eff0,2c:eff1

Differential Revision: https://reviews.llvm.org/D114901
2021-12-10 14:34:33 -06:00
AndreyChurbanov
1031e43052 [OpenMP] libomp: fix Fortran header: lines exceeded 72-char length
Added line continuation to two long lines in Fortran header.

Differential Revision: https://reviews.llvm.org/D114537
2021-12-10 16:23:21 +03:00
AndreyChurbanov
4dd8fccb71 [OpenMP] libomp: Fix crash if application send us negative thread_limit value
Regardless that specification requires thread_limit to be positive,
it is better to warn user instead of crash in case the value is negative.

Differential Revision: https://reviews.llvm.org/D115340
2021-12-08 19:02:57 +03:00
Kazushi (Jam) Marukawa
5e2358c781 [runtimes][openmp] Change to not treat ARCH-unknown-linux-gnu as errors
When OpenMP is compiled as a part runtimes for multiple targets, openmp
is compiled under build/runtimes/runtimes-arch-unknown-linux-gnu-bins
directory.  Old implementation treats this directory name as errors.
This patch adds a guard like "[Uu]known[^-]".

Reviewed By: jdoerfert

Differential Revision: https://reviews.llvm.org/D114346
2021-12-01 08:33:37 +09:00
Alexey Bataev
80256605f8 [OpenMP] support depend clause for taskwait directive, by Deepak
Eachempati.

This patch adds clang (parsing, sema, serialization, codegen) support for the 'depend' clause on the 'taskwait' directive.

Reviewed By: ABataev

Differential Revision: https://reviews.llvm.org/D113540
2021-11-19 06:30:17 -08:00
Peyton, Jonathan L
a733b18bdb [OpenMP][libomp] Enable HWLOC topology detection of multiple CPU kinds
Teach the HWLOC topology method how to detect Atom and Core
types so hybrid CPUs are properly detected and represented when using
the HWLOC topology method.

Differential Revision: https://reviews.llvm.org/D112270
2021-11-17 16:30:18 -06:00
Peyton, Jonathan L
286094af9b [OpenMP][libomp] Improve Windows Processor Group handling within topology
The current implementation of Windows Processor Groups has
a separate topology method to handle them. This patch deprecates
that specific method and uses the regular CPUID topology
method by default and inserts the Windows Processor Group objects
in the topology manually.

Notes:
* The preference for processor groups is lowered to a value less than
  socket so that the user will see sockets in the KMP_AFFINITY=verbose
  output instead of processor groups when sockets=processor groups.
* The topology's capacity is modified to handle additional topology layers
  without the need for reallocation.
* If a user asks for a granularity setting that is "above" the processor
  group layer, then the granularity is adjusted "down" to the processor
  group since this is the coarsest layer available for threads.

Differential Revision: https://reviews.llvm.org/D112273
2021-11-17 16:29:01 -06:00
Peyton, Jonathan L
1dd797168e [OpenMP][libomp] Add support for offline CPUs in Linux
If some CPUs are offline, then make sure they are not included in the
fullMask even if norespect is given to KMP_AFFINITY.

Differential Revision: https://reviews.llvm.org/D112274
2021-11-17 16:28:01 -06:00
Peyton, Jonathan L
a0afb9d0fc [OpenMP][libomp] Allow users to specify KMP_HW_SUBSET in any order
Remove restriction forcing users to specify the KMP_HW_SUBSET value in
topology order. This patch sorts the user KMP_HW_SUBSET value before
trying to apply it. For example: 1s,4c,2t is equivalent to 2t,1s,4c

Differential Revision: https://reviews.llvm.org/D112027
2021-11-17 15:27:37 -06:00
Jonathan Peyton
c46becf500 [OpenMP][libomp][NFC] Remove non-ASCII apostrophe in comment 2021-11-17 14:46:40 -06:00
Martin Storsjö
9b2b549837 [OpenMP] Silence build warnings when built with MinGW
There's an attempt to upstream this change in
https://github.com/intel/ittapi/pull/25 too.

Differential Revision: https://reviews.llvm.org/D114069
2021-11-17 18:51:18 +02:00
Nawrin Sultana
7a5680233e [OpenMP] Set default blocktime to 0 for hybrid cpu
Differential Revision:https://reviews.llvm.org/D113012
2021-11-12 12:05:35 -06:00
Bran Hagger
9f15cacc2e [OpenMP] Allow building libomp using Microsoft Visual C++ naming scheme
Differential Revision: https://reviews.llvm.org/D110354
2021-11-11 13:11:56 -06:00
Joachim Protze
52da6f562e Revert "[openmp] Add OMPT initialization in libomptarget"
Reverting initial OMPT for target implementation in favor of a
different implementation.

This reverts commit 3bc8ce5dd7.
2021-11-10 12:44:25 +01:00
Jonathan Peyton
48b67dca2c [OpenMP][libomp][CMake] use uppercase_CMAKE_BUILD_TYPE
Have standalone builds define uppercase_CMAKE_BUILD_TYPE and use it.
llvm/CMakeLists.txt defines uppercase_CMAKE_BUILD_TYPE for regular LLVM
builds with OpenMP enabled.

Differential Revision: https://reviews.llvm.org/D112951
2021-11-09 11:03:04 -06:00
Quinn Pham
c3b15b71ce [NFC] Inclusive Language: change master to main for .chm files
[NFC] As part of using inclusive language within the llvm project,
this patch replaces master with main when referring to `.chm` files.

Reviewed By: teemperor

Differential Revision: https://reviews.llvm.org/D113299
2021-11-08 08:23:04 -06:00
@t-msn
0808d956c4 [OpenMP] libomp: Fix handling of barrier pattern environment variables
It is better to set all barrier patterns to use "dist" when at least
one environment variable specifies "dist". Otherwise if only one
environment is set to "dist" and others left blank inadvertently,
it would result in mixing dist barrier with default hyper barrier
pattern.

Differential Revision: https://reviews.llvm.org/D112597
2021-11-08 15:01:26 +03:00
Med Ismail Bennani
797b50d4be Revert "Use GNUInstallDirs to support custom installation dirs. -- LLVM"
This reverts commit 6fd2db04d0 since it
broke GreenDragon LLDB-Incremental bot:

https://green.lab.llvm.org/green/job/lldb-cmake/37560/console

Signed-off-by: Med Ismail Bennani <medismail.bennani@gmail.com>
2021-11-02 19:11:44 +01:00
John Ericson
6fd2db04d0 Use GNUInstallDirs to support custom installation dirs. -- LLVM
This is a new draft of D28234. I previously did the unorthodox thing of
pushing to it when I wasn't the original author, but since this version

- Uses `GNUInstallDirs`, rather than mimics it, as the original author
  was hesitant to do but others requested.

- Is much broader, effecting many more projects than LLVM itself.

I figured it was time to make a new revision.

I am using this patch (and many back-ports) as the basis of
https://github.com/NixOS/nixpkgs/pull/111487 for my distro (NixOS). It
looked like people were generally on board in D28234, but I make note of
this here in case extra motivation is useful.

---

As pointed out in the original issue, a central tension is that LLVM
already has some partial support for these sorts of things. For example
`LLVM_LIBDIR_SUFFIX`, or `COMPILER_RT_INSTALL_PATH`. Because it's not
quite clear yet what to do about those, we are holding off on changing
libdirs and `compiler-rt`. for this initial PR.

---

On the advice of @lebedev.ri, I am splitting this up a bit per
subproject, starting with LLVM. To allow it to be more easily reviewed. This and the subsequent patch must be landed together, as this will not build alone. But the rest can be landed on their own.

Reviewed By: compnerd

Differential Revision: https://reviews.llvm.org/D100810
2021-11-02 10:23:30 -04:00
AndreyChurbanov
a64797b5b8 [OpenMP][NFC] disable test on power because of -mlong-double-80 option 2021-10-27 16:54:44 +03:00
AndreyChurbanov
c704b25b44 [OpenMP] libomp: Fix possible NULL dereference.
According to dlsym description, the value of symbol could be NULL,
and there is no error in this case. Thus dlerror will also return NULL in
this case. We need to check the value returned by dlerror before printing it.

Differential Revision: https://reviews.llvm.org/D112174
2021-10-27 16:54:44 +03:00
AndreyChurbanov
e38a1deb66 [OpenMP] libomp: disable definitions of 5.1 atomics for non-x86 arch.
Declarations of 5.1 atomic entries were added under
"#if KMP_ARCH_X86 || KMP_ARCH_X86_64" in kmp_atomic.h,
but definitions of the functions missed architecture guard in kmp_atomic.cpp.
As a result mangled symbols were available on non-x86 architecture.
The patch eliminates these unexpected symbols from the library.

Differential Revision: https://reviews.llvm.org/D112261
2021-10-25 21:17:26 +03:00
Vladimir Inđić
f41d08540b [OpenMP][OMPT] thread_num determination during execution of nested serialized parallel regions
__ompt_get_task_info_internal function is adapted to support thread_num
determination during the execution of multiple nested serialized
parallel regions enclosed by a regular parallel region.

Consider the following program that contains parallel region R1 executed
by two threads. Let the worker thread T of region R1 executes serialized
parallel regions R2 that encloses another serialized parallel region R3.
Note that the thread T is the master thread of both R2 and R3 regions.

Assume that __ompt_get_task_info_internal function is called with the
argument "ancestor_level == 1" during the execution of region R3.
The function should determine the "thread_num" of the thread T inside
the team of region R2, whose implicit task is at level 1 inside the
hierarchy of active tasks. Since the thread T is the master thread of
region R2, one should expected that "thread_num" takes a value 0.
After the while loop finishes, the following stands: "lwt != NULL",
"prev_lwt == NULL", "prev_team" represents the team information about
the innermost serialized parallel region R3. This results in executing
the assignment "thread_num = prev_team->t.t_master_tid". Note that
"prev_team->t.t_master_tid" was initialized at the moment of
R2’s creation and represents the "thread_num" of the thread T inside
the region R1 which encloses R2. Since the thread T is the worker thread
of the region R1, "the thread_num" takes value 1, which is a contradiction.

This patch proposes to use "lwt" instead of "prev_lwt" when determining
the "thread_num". If "lwt" exists, the task at the requested level belongs
to the serialized parallel region. Since the serialized parallel region
is executed by one thread only, the "thread_num" takes value 0.

Similarly, assume that __ompt_get_task_info_internal function is called
with the argument "ancestor_level == 2" during the execution of region R3.
The function should determine the "thread_num" of the thread T inside the
team of region R1. Since the thread is the worker inside the region R1,
one should expected that "thread_num" takes value 1. After the loop finishes,
the following stands: "lwt == NULL", "prev_lwt != NULL", "prev_team" represents
the team information about the innermost serialized parallel region R3.
This leads to execution of the assignment "thread_num = 0", which causes
a contradiction.

Ignoring the "prev_lwt" leads to executing the assignment
"thread_num = prev_team->t.t_master_tid" instead. From the previous explanation,
it is obvious that "thread_num" takes value 1.

Note that the "prev_lwt" variable is marked as unnecessary and thus removed.

This patch introduces the test case which represents the OpenMP program
described earlier in the summary.

Differential Revision: https://reviews.llvm.org/D110699
2021-10-25 18:21:20 +02:00