Merge commit 5300a6731e98 from llvm-project (by Jonathan Peyton):

[OpenMP] Fix re-locking hang found in issue 86684 (#88539)

This was initially reported here (including stacktraces):
https://stackoverflow.com/questions/78183545/does-compiling-imagick-with-openmp-enabled-in-freebsd-13-2-cause-sched-yield

If `__kmp_register_library_startup()` detects that another instance of
the library is present, `__kmp_is_address_mapped()` is eventually
called. which uses `kmpc_alloc()` to allocate memory. This function
calls `__kmp_entry_thread()` to access the thread-local memory pool,
which is a bad idea during initialization. This macro internally calls
`__kmp_get_global_thread_id_reg()` which sets the bootstrap lock at the
beginning (before calling `__kmp_register_library_startup()`).

The fix is to use `KMP_INTERNAL_MALLOC()`/`KMP_INTERNAL_FREE()` instead
of `kmpc_malloc()`/`kmpc_free()`. `KMP_INTERNAL_MALLOC` and
`KMP_INTERNAL_FREE` do not use any bootstrap locks. They just translate
to `malloc()`/`free()` and are meant to be used during library
initialization before other library-specific allocators have been
initialized.

Fixes: #86684

This should fix OpenMP processes sometimes getting locked with 100% CPU
usage, endlessly calling sched_yield(2).

PR: 278845
Reported by: Cassidy B. Larson <cbl@cbl.us>
MFC after: 3 days

Merge llvm-project release/18.x llvmorg-18.1.3-0-gc13b7485b879

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvm-project release/18.x llvmorg-18.1.3-0-gc13b7485b879.

PR: 276104
MFC after: 1 month

Merge llvm-project main llvmorg-18-init-16864-g3b3ee1f53424

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvm-project main llvmorg-18-init-16864-g3b3ee1f53424.

PR: 276104
MFC after: 1 month

Merge llvm-project main llvmorg-18-init-16595-g7c00a5be5cde

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvm-project main llvmorg-18-init-16595-g7c00a5be5cde.

PR: 276104
MFC after: 1 month

Merge llvm-project main llvmorg-18-init-15088-gd14ee76181fb

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvm-project main llvmorg-18-init-15088-gd14ee76181fb.

PR: 276104
MFC after: 1 month

Merge llvm-project main llvmorg-17-init-19304-gd0b54bb50e51

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvm-project main llvmorg-17-init-19304-gd0b54bb50e51, the
last commit before the upstream release/17.x branch was created.

PR: 273753
MFC after: 1 month

Merge llvm-project main llvmorg-16-init-18548-gb0daacf58f41

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-16-init-18548-gb0daacf58f41.

PR: 271047
MFC after: 1 month

Merge llvm-project main llvmorg-15-init-17485-ga3e38b4a206b

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-15-init-17485-ga3e38b4a206b.

PR: 265425
MFC after: 2 weeks

Merge llvm-project main llvmorg-14-init-10186-gff7f2cfa959b

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-14-init-10186-gff7f2cfa959b.

PR: 261742
MFC after: 2 weeks

Merge llvm-project main llvmorg-13-init-16847-g88e66fa60ae5

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-13-init-16847-g88e66fa60ae5, the last commit before
the upstream release/13.x branch was created.

PR: 258209
MFC after: 2 weeks

Merge llvm-project main llvmorg-12-init-17869-g8e464dd76bef

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-12-init-17869-g8e464dd76bef, the last commit before the
upstream release/12.x branch was created.

PR: 255570
MFC after: 6 weeks

Merge llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and openmp
master 2e10b7a39b9, the last commit before the llvmorg-12-init tag, from
which release/11.x was branched.

Note that for now, I rolled back all our local changes to make merging
easier, and I will reapply the still-relevant ones after updating to
11.0.0-rc1.

Merge ^/vendor/lvm-project/master up to its last change (upstream commit
e26a78e70), and resolve conflicts.

Merge ^/vendor/llvm-openmp/dist up to its last change, and resolve conflicts.

Move all sources from the llvm project into contrib/llvm-project.

This uses the new layout of the upstream repository, which was recently
migrated to GitHub, and converted into a "monorepo". That is, most of
the earlier separate sub-projects with their own branches and tags were
consolidated into one top-level directory, and are now branched and
tagged together.

Updating the vendor area to match this layout is next.

Merge llvm-project main llvmorg-17-init-19304-gd0b54bb50e51

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvm-project main llvmorg-17-init-19304-gd0b54bb50e51, the
last commit before the upstream release/17.x branch was created.

PR: 273753
MFC after: 1 month

Merge llvm-project main llvmorg-16-init-18548-gb0daacf58f41

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-16-init-18548-gb0daacf58f41.

PR: 271047
MFC after: 1 month

Merge llvm-project main llvmorg-15-init-17485-ga3e38b4a206b

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-15-init-17485-ga3e38b4a206b.

PR: 265425
MFC after: 2 weeks

Merge llvm-project main llvmorg-14-init-10186-gff7f2cfa959b

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-14-init-10186-gff7f2cfa959b.

PR: 261742
MFC after: 2 weeks

Merge llvm-project main llvmorg-13-init-16847-g88e66fa60ae5

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-13-init-16847-g88e66fa60ae5, the last commit before
the upstream release/13.x branch was created.

PR: 258209
MFC after: 2 weeks

Merge llvm-project main llvmorg-12-init-17869-g8e464dd76bef

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-12-init-17869-g8e464dd76bef, the last commit before the
upstream release/12.x branch was created.

PR: 255570
MFC after: 6 weeks

Merge llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and openmp
master 2e10b7a39b9, the last commit before the llvmorg-12-init tag, from
which release/11.x was branched.

Note that for now, I rolled back all our local changes to make merging
easier, and I will reapply the still-relevant ones after updating to
11.0.0-rc1.

Merge ^/vendor/lvm-project/master up to its last change (upstream commit
e26a78e70), and resolve conflicts.

Merge ^/vendor/llvm-openmp/dist up to its last change, and resolve conflicts.

Move all sources from the llvm project into contrib/llvm-project.

This uses the new layout of the upstream repository, which was recently
migrated to GitHub, and converted into a "monorepo". That is, most of
the earlier separate sub-projects with their own branches and tags were
consolidated into one top-level directory, and are now branched and
tagged together.

Updating the vendor area to match this layout is next.

Merge llvm-project main llvmorg-16-init-18548-gb0daacf58f41

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-16-init-18548-gb0daacf58f41.

PR: 271047
MFC after: 1 month

Merge llvm-project main llvmorg-15-init-17485-ga3e38b4a206b

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-15-init-17485-ga3e38b4a206b.

PR: 265425
MFC after: 2 weeks

Merge llvm-project main llvmorg-14-init-10186-gff7f2cfa959b

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-14-init-10186-gff7f2cfa959b.

PR: 261742
MFC after: 2 weeks

Merge llvm-project main llvmorg-13-init-16847-g88e66fa60ae5

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-13-init-16847-g88e66fa60ae5, the last commit before
the upstream release/13.x branch was created.

PR: 258209
MFC after: 2 weeks

Merge llvm-project main llvmorg-12-init-17869-g8e464dd76bef

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-12-init-17869-g8e464dd76bef, the last commit before the
upstream release/12.x branch was created.

PR: 255570
MFC after: 6 weeks

Merge llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and openmp
master 2e10b7a39b9, the last commit before the llvmorg-12-init tag, from
which release/11.x was branched.

Note that for now, I rolled back all our local changes to make merging
easier, and I will reapply the still-relevant ones after updating to
11.0.0-rc1.

Merge ^/vendor/lvm-project/master up to its last change (upstream commit
e26a78e70), and resolve conflicts.

Merge ^/vendor/llvm-openmp/dist up to its last change, and resolve conflicts.

Move all sources from the llvm project into contrib/llvm-project.

This uses the new layout of the upstream repository, which was recently
migrated to GitHub, and converted into a "monorepo". That is, most of
the earlier separate sub-projects with their own branches and tags were
consolidated into one top-level directory, and are now branched and
tagged together.

Updating the vendor area to match this layout is next.

Merge llvm-project main llvmorg-15-init-17485-ga3e38b4a206b

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-15-init-17485-ga3e38b4a206b.

PR: 265425
MFC after: 2 weeks

Merge llvm-project main llvmorg-14-init-10186-gff7f2cfa959b

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-14-init-10186-gff7f2cfa959b.

PR: 261742
MFC after: 2 weeks

Merge llvm-project main llvmorg-13-init-16847-g88e66fa60ae5

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-13-init-16847-g88e66fa60ae5, the last commit before
the upstream release/13.x branch was created.

PR: 258209
MFC after: 2 weeks

Merge llvm-project main llvmorg-12-init-17869-g8e464dd76bef

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-12-init-17869-g8e464dd76bef, the last commit before the
upstream release/12.x branch was created.

PR: 255570
MFC after: 6 weeks

Merge llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and openmp
master 2e10b7a39b9, the last commit before the llvmorg-12-init tag, from
which release/11.x was branched.

Note that for now, I rolled back all our local changes to make merging
easier, and I will reapply the still-relevant ones after updating to
11.0.0-rc1.

Merge ^/vendor/lvm-project/master up to its last change (upstream commit
e26a78e70), and resolve conflicts.

Merge ^/vendor/llvm-openmp/dist up to its last change, and resolve conflicts.

Move all sources from the llvm project into contrib/llvm-project.

This uses the new layout of the upstream repository, which was recently
migrated to GitHub, and converted into a "monorepo". That is, most of
the earlier separate sub-projects with their own branches and tags were
consolidated into one top-level directory, and are now branched and
tagged together.

Updating the vendor area to match this layout is next.

Merge llvm-project main llvmorg-14-init-10186-gff7f2cfa959b

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-14-init-10186-gff7f2cfa959b.

PR: 261742
MFC after: 2 weeks

Merge llvm-project main llvmorg-13-init-16847-g88e66fa60ae5

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-13-init-16847-g88e66fa60ae5, the last commit before
the upstream release/13.x branch was created.

PR: 258209
MFC after: 2 weeks

Merge llvm-project main llvmorg-12-init-17869-g8e464dd76bef

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-12-init-17869-g8e464dd76bef, the last commit before the
upstream release/12.x branch was created.

PR: 255570
MFC after: 6 weeks

Merge llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and openmp
master 2e10b7a39b9, the last commit before the llvmorg-12-init tag, from
which release/11.x was branched.

Note that for now, I rolled back all our local changes to make merging
easier, and I will reapply the still-relevant ones after updating to
11.0.0-rc1.

Merge ^/vendor/lvm-project/master up to its last change (upstream commit
e26a78e70), and resolve conflicts.

Merge ^/vendor/llvm-openmp/dist up to its last change, and resolve conflicts.

Move all sources from the llvm project into contrib/llvm-project.

This uses the new layout of the upstream repository, which was recently
migrated to GitHub, and converted into a "monorepo". That is, most of
the earlier separate sub-projects with their own branches and tags were
consolidated into one top-level directory, and are now branched and
tagged together.

Updating the vendor area to match this layout is next.

Merge llvm-project main llvmorg-13-init-16847-g88e66fa60ae5

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-13-init-16847-g88e66fa60ae5, the last commit before
the upstream release/13.x branch was created.

PR: 258209
MFC after: 2 weeks

Merge llvm-project main llvmorg-12-init-17869-g8e464dd76bef

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-12-init-17869-g8e464dd76bef, the last commit before the
upstream release/12.x branch was created.

PR: 255570
MFC after: 6 weeks

Merge llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and openmp
master 2e10b7a39b9, the last commit before the llvmorg-12-init tag, from
which release/11.x was branched.

Note that for now, I rolled back all our local changes to make merging
easier, and I will reapply the still-relevant ones after updating to
11.0.0-rc1.

Merge ^/vendor/lvm-project/master up to its last change (upstream commit
e26a78e70), and resolve conflicts.

Merge ^/vendor/llvm-openmp/dist up to its last change, and resolve conflicts.

Move all sources from the llvm project into contrib/llvm-project.

This uses the new layout of the upstream repository, which was recently
migrated to GitHub, and converted into a "monorepo". That is, most of
the earlier separate sub-projects with their own branches and tags were
consolidated into one top-level directory, and are now branched and
tagged together.

Updating the vendor area to match this layout is next.

Move all sources from the llvm project into contrib/llvm-project.

This uses the new layout of the upstream repository, which was recently
migrated to GitHub, and converted into a "monorepo". That is, most of
the earlier separate sub-projects with their own branches and tags were
consolidated into one top-level directory, and are now branched and
tagged together.

Updating the vendor area to match this layout is next.