[PATCH] D128914: [HIP] Add support for handling HIP in the linker wrapper

[Artem Belevich via Phabricator via cfe-commits]

tra added a comment.

In D128914#3643495 <https://reviews.llvm.org/D128914#3643495>, @jhuber6 wrote:

> Yes, it's actually pretty difficult to find a CUDA application using `fgpu-rdc`. It seems much more common to just stick everything that's needed in the file.I've considered finding a CUDA / HIP benchmark suite and comparing compile times using the new driver stuff. The benefit of having `fgpu-rdc` be the default is that device code basically behaves exactly like host code and LTO makes `fgpu-rdc` behave like `fno-gpu-rdc` performance wise. The downside, as you mentioned, is compile time.

For what it's worth, NCCL <https://developer.nvidia.com/nccl> is the only nontrivial library that needs RDC compilation that I'm aware of.
It's also self-contained for RDC purposes we only need to use RDC on the library TUs and do not need to propagate it to all CUDA TUs in the build.

I believe such 'constrained' RDC compilation will likely be the reasonable practical trade-off. It may not become the default compilation mode, but we should be able to control where the "fully linked GPU executable" boundary is and it's not necessarily going to match the fully-linked host executable.


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