[SYCL] Skip free-function kernel global-info updates after runtime teardown (#22946)
This is a SYCL runtime bug. Likely introduced by intel/llvm PR #20422 .
For each TU containing a SYCL free-function kernel, the compiler emits a
static GlobalMapUpdater object in the integration header. Before #20422
it had only a constructor (registers kernel names). #20422 added a
destructor that calls `sycl::detail::free_function_info_map::remove(...)
→ ProgramManager::unRegisterKernelGlobalInfo`, which mutates state owned
by libsycl's `GlobalHandler` singleton.
The crash is a cross-shared-object static-destruction-order problem:
GlobalMapUpdater updater lives in liboneccl_v1.so with no destructor
priority.
libsycl tears down its GlobalHandler (and the ProgramManager map) in
shutdown_late(), run from __attribute__((destructor(110))) in
`libsycl.so`.
Destructor priority only orders teardown within a single shared object.
It does not order an independent .so (liboneccl) against libsycl. When
libsycl is torn down before oneCCL's updater destructor runs, that
destructor calls into an already-freed/unloaded libsycl → SIGBUS.
This triggers merely by linking libccl.so with a free-function kernel
present; no oneCCL API call is needed, because updater is a static
object whose destructor runs at process exit regardless.
On the workaround
`unRegisterKernelGlobalInfo/getInstance` should be robust to a torn-down
runtime, and/or the map cleanup should be skipped at process termination
(it's only meaningful for a true mid-process dlclose).
llvm
8c64b646 - [SYCL] Skip free-function kernel global-info updates after runtime teardown (#22946)
