jhuber6 wrote:
> > I don't think we want to support this. `-march` was the wrong option to use
> > in the first place, and upstream LLVM never supported specifying multiple
> > device images with `-march` so there isn't a legacy argument in trunk.
> > However, AOMP did support this and if it's deemed too disruptive to request
> > users move to `--offload-arch=a,b,c` then we can carry that change in the
> > fork.
> > > It will fix tests like:
> > > [targetid_multi_image](https://github.com/ROCm/aomp/tree/aomp-dev/test/smoke/targetid_multi_image)
> >
> >
> > I think the easier way to fix this is to update the Makefile.
>
> Irrespective of what AOMP does, I think it makes sense to ensure parity
> between the two ways of specifying architecture. People have been
> historically using `-Xopenmp-target -march` style, and using the same for
> multiple architectures seems to be the most obvious choice. Isn't it quite
> confusing to tell the users that they can use `offload-arch` style for single
> as well as multiple archs, but can use `-march` style only for single arch?
`-march` was the wrong option to use for this from the beginning. It's supposed
to be an overriding option and it shouldn't be overloaded to mean something
different here. In LLVM / trunk we never supported multiple architectures with
the `-march` option so I don't see any reason to start now. `--offload-arch=`
is a complete replacement for this behavior and I consider the single `-march`
option to be legacy. Even within this it's divergent because HIP / OpenCL /
AMDGPU use `-mcpu` but the OpenMP toolchain ignored that and uses `-march=`.
Using `--offload-arch=` is a direct replacement for `-march` in all use-cases.
It's also easier to use and interoperable with CUDA. I would just change the
test, you can replace every use of `-march` with `--offload-arch` and it will
work. See the following.
```console
> clang input.c -fopenmp -fopenmp-targets=amdgcn-amd-amdhsa,nvptx64-nvidia-cuda
> -Xopenmp-target=amdgcn-amd-amdhsa --offload-arch=gfx1030
> -Xopenmp-target=amdgcn-amd-amdhsa --offload-arch=gfx90a
> -Xopenmp-target=nvptx64-nvidia-cuda --offload-arch=sm_89
> llvm-objdump --offloading a.out
a.out: file format elf64-x86-64
OFFLOADING IMAGE [0]:
kind elf
arch sm_89
triple nvptx64-nvidia-cuda
producer openmp
OFFLOADING IMAGE [1]:
kind elf
arch gfx90a
triple amdgcn-amd-amdhsa
producer openmp
OFFLOADING IMAGE [2]:
kind elf
arch gfx1030
triple amdgcn-amd-amdhsa
producer openmp
```
https://github.com/llvm/llvm-project/pull/92290
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