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See the [roadmap](https://github.com/rust-cuda/wg/blob/master/documents/roadmap.md). **Goal**: cross-compiling to `nvptx` from the Tier-1 `x86_64` targets should always work. This moves `nvptx` from a Tier-3 to a Tier-2 target. **Main objective**: create an example host crate that links to a device crate containing a simple kernel using some `core::arch::nvptx` intrinsics and math function. Launch the kernel from the host crate using `cuda-sys`. Compiling these crates from the `x86_64` Tier-1 targets should never fail. That is, PRs to `rustc`, `libcore` (`stdsimd`, etc.) that would break the build for this example crate should not be merge-able - that is, the CI systems of `rustc`, `stdsimd`, etc. will detect this and fail. Our current goal is only about making sure that cross-compiling always works. That is, ensuring that the host crate actually runs correctly and passes a run-time tests, e.g., with the kernel running on a real GPU, is not necessary to achieve our goal and is not part of the objective - it could be our next goal. This main objective is split into 4 sub-objectives: **compiler**: we need to make sure that the compiler is always able to compile `nvptx` kernels without erroring. We should add tests for this, and enable those in Rust's CI. This would be codegen tests, compile-pass tests, etc. No run-time tests at this point. **library**: we need to make sure that the `nvptx` intrinsics (e.g. `syncthreads`) always compile. We need to add tests to `stdsimd` to build these intrinsics. **linker**: we need to make sure that linking `nvptx` to the host crate always work, we need to test this, and we need to make sure that rustc changes are blocked on not breaking this. **testing**: our first focus is on getting the toolchain to an "always builds" state. However, "always builds" is not very useful if nothing works at run-time. We should implement ways of testing that the `ptx` code generated is correct, without doing run-time tests.
No due date