On MinGW, thread_local storage is emutls: libgcc frees a thread's blocks
from a winpthread key destructor when the thread function returns, and
the CRT runs the thread_local destructors later, from the module's TLS
callback at thread detach. The destructors of the driver's non-trivial
thread_locals (the deferred label queue, packet profile, capture and
revalidation scratch vectors, build profile, memory counters, disk cache
buffers) therefore ran on freed storage. Under the debug heap the flip
test failed on every run at the queue worker's exit after the injected
flip failure; without it the use-after-free showed up as intermittent
heap corruption or a stack overflow on the Windows CI job.
ShaderRecompiler::ThreadOwned keeps such state behind a trivially
destructible thread_local pointer and deletes it from its own pthread key
destructor, which receives the objects directly instead of reading
emutls. The driver no longer registers any thread_local destructor.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Chad