This is a part of allocator patch since I want to make sure the TLS for
allocators are correctly handled.
TLS dtors are not invoked on exit previously. This departures from major
libc implementations.
This PR fixes the issue by aligning the behavior with bionic.
https://android.googlesource.com/platform/bionic/+/refs/heads/main/libc/bionic/exit.cpp
I believe the finalization order is also consistent with glibc now:
On main thread exiting:
- pthread_key dtors are not called (unless exiting with `pthread_exit`)
- `__cxa` based tls dtors are called
- `::__cxa_atexit` and `::atexit` dtors are called
- `.fini` dtors are called
- In /libc/src/__support/ OSUtil, changed quick_exit to just exit, and
put in namespace
LIBC_NAMESPACE::internal.
- In /libc/src/stdlib added quick_exit
- Added test files for quick_exit
The usage of __builtin_unreachable after calls to quick_exit were distressing.
If a function is properly marked [[noreturn]] then __builtin_unreachable is not
necessary.
Looking into this further, we seem to have header only implementations for CPU
targets. The inline nature of these functions is curious; we're going to exit,
it doesn't matter if we need to pay the call of a function or not. If we just
make these functions have distinct TUs rather than be header only, we can clean
up the cmake rules for quick_exit which were different between CPU and GPU.
Remove darwin support for quick_exit. This isn't being tested, and we can bring
it back when necessary.
I'm trying to break up the pieces of supporting __cxa_finalize into smaller
commits. Provide this symbol first, and make use of it from exit.
Next will be to store __dso_handle, then finally to only run callbacks that
were registered from a specific dso.
Link: #85651
Link: https://itanium-cxx-abi.github.io/cxx-abi/abi.html#dso-dtor
The `exit` entrypoint calls into `quick_exit` which is marked noreturn
in some cases. This will cause errors because we then have control flow
externally. This warning can be silenced by using a
`__builtin_unreachable` instruction accordingly.
Reviewed By: sivachandra, lntue
Differential Revision: https://reviews.llvm.org/D152323
This patch implements the `exit` function on the GPU. This required
breaking the entrypoints calling eachother on `linux` since this doesn't
work with a non-aliased target. This is only partial support because
full support requires a malloc / free implementation for the exit
callbacks array.
Reviewed By: sivachandra
Differential Revision: https://reviews.llvm.org/D149363
The new container is used to store atexit callbacks. This way, we avoid
the possibility of the destructor of the container itself getting added
as an at exit callback.
Reviewed By: abrachet
Differential Revision: https://reviews.llvm.org/D121350
Often atexit is implemented using __cxa_atexit. I have not implemented __cxa_atexit here because it potentially requires more discussion. It is unique for llvm-libc (I think) that it is an exported symbol that wouldn’t be defined in any spec file because it doesn’t have a header. Implementing it will be trivial given what is here already, but I figured it would be more contentious so it can be implemented later.
Reviewed By: lntue
Differential Revision: https://reviews.llvm.org/D119512
