Summary:
We use the infrastructure to stand up a pretend hosted environment on
the GPU. Part of that is calling exit codes and handling the callback.
Exiting from inside a GPU region is problematic as it actually relies on
a lot of GPU magic behind the scenes. This is at least *correct* now as
we use `quick_exit` on the CPU when the GPU calls `exit`. However,
calling `quick_exit` will interfere with instrumentation or benchmarking
that expects a nice teardown order. For normal execution we should do
the friendly option and let the loader utility clean everything up
manually.
Summary:
There were a few issues with the first one, leading to some errors and
warnings. Most importantly, this was building on MSVC which isn't
supported.
Summary:
These tools `amdhsa-loader` and `nvptx-loader` are used to execute unit
tests directly on the GPU. We use this for `libc` and `libcxx` unit
tests as well as general GPU experimentation. It looks like this.
```console
> clang++ main.cpp --target=amdgcn-amd-amdhsa -mcpu=native -flto -lc ./lib/amdgcn-amd-amdhsa/crt1.o
> llvm-gpu-loader a.out
Hello World!
```
Currently these are a part of the `libc` project, but this creates
issues as `libc` itself depends on them to run tests. Right now we get
around this by force-including the `libc` project prior to running the
runtimes build so that this dependency can be built first. We should
instead just make this a simple LLVM tool so it's always available.
This has the effect of installing these by default now instead of just
when `libc` was enabled, but they should be relatively small. Right now
this only supports a 'static' configuration. That is, we locate the CUDA
and HSA dependencies at LLVM compile time. In the future we should be
able to provide this by default using `dlopen` and some API.
I don't know if it's required to reformat all of these names since they
used the `libc` naming convention so I just left it for now.
