In order to do offloading compilation we need to embed files into the
host and create fatbainaries. Clang uses a special binary format to
bundle several files along with their metadata into a single binary
image. This is currently performed using the `-fembed-offload-binary`
option. However this is not very extensibile since it requires changing
the command flag every time we want to add something and makes optional
arguments difficult. This patch introduces a new tool called
`clang-offload-packager` that behaves similarly to CUDA's `fatbinary`.
This tool takes several input files with metadata and embeds it into a
single image that can then be embedded in the host.
Reviewed By: tra
Differential Revision: https://reviews.llvm.org/D125165
Currently we require the `-fopenmp-targets=` option to specify the
triple to use for the offloading toolchains, and the `-Xopenmp-target=`
option to specify architectures to a specific toolchain. The changes
made in D124721 allowed us to use `--offload-arch=` to specify multiple
target architectures. However, this can become combersome with many
different architectures. This patch introduces functinality that
attempts to deduce the target triple and architectures from the
offloading action. Currently we will deduce known GPU architectures when
only `-fopenmp` is specified.
This required a bit of a hack to cache the deduced architectures,
without this we would've just thrown an error when we tried to look up
the architecture again when generating the job. Normally we require the
user to manually specify the toolchain arguments, but here they would
confict unless we overrode them.
Depends on: D124721
Reviewed By: saiislam
Differential Revision: https://reviews.llvm.org/D125050
Joseph Huber