[PATCH] D47394: [OpenMP][Clang][NVPTX] Replace bundling with partial linking for the OpenMP NVPTX device offloading toolchain

[Jonas Hahnfeld via Phabricator via cfe-commits]

Hahnfeld added a comment.

In https://reviews.llvm.org/D47394#1115086, @tra wrote:

> On one hand I can see how being able to treat GPU-side binaries as any other host files is convenient. On the other hand, this convenience comes with the price of targeting only NVPTX. This seems contrary to OpenMP's goal of supporting many different kinds of accelerators. I'm not sure what's the consensus in the OpenMP community these days, but I vaguely recall that generic bundling/unbundling was explicitly chosen over vendor-specific encapsulation in host .o when the bundling was implemented. If the underlying reasons have changed since then it would be great to hear more details about that.


I second this statement, static linking might come handy for all targets and Clang should try to avoid vendor specific solutions as much as possible.

In a discussion off-list I proposed adding constructor functions to all object files and handle them like shared libraries are already handled today (ie register separately and let the runtime figure out how to relocate symbols in different translation units). I don't have an implementation of that approach so I can't claim that it works and doesn't have a huge performance impact (which we don't want either), but it should be agnostic of the offloading target so it may be worth investigating.


Repository:
  rC Clang

https://reviews.llvm.org/D47394