Time to switch to `icx/icpx` for Intel C/C++ compilers

[ocaisa]

The current recommendation from Intel is that we should be using the icx/icpx LLVM-based compilers by default

[ocaisa]

I think this would mean adding a version check to https://github.com/easybuilders/easybuild-framework/blob/develop/easybuild/toolchains/compiler/intel_compilers.py#L59 and overriding the values self.variables['CXX']/ self.variables['CC'] (that's assuming none of the compiler arguments have changed)

[ocaisa]

Looking at https://www.intel.com/content/www/us/en/developer/articles/guide/porting-guide-for-icc-users-to-dpcpp-or-icx.html

- ICX drivers icx and icpx will accept ICC Classic Compiler options or Clang*/LLVM Compiler options.
  - Clang*/LLVM Compiler options are interpreted directly.
  - Classic ICC Compiler options passed to ICX are translated to their Clang*/LLVM equivalents, wherever possible.
- Not all ICC Classic options are accepted and/or implemented in ICX.

We would also need to use -fiopenmp for OpenMP (according to that page).

I wonder if we will also end up with version differences compared to ifort?

[akesandgren]

Should we do this for the 2022a toolchain version?

[boegel]

@akesandgren The idea is to first implement support to opt-in to using icx/icpx/ifx via a toolchain option, and then later considering to switch to it by default perhaps, once it's been battle-tested.

There's no way we're going to make this the default for the next common toolchain versions, but it would be nice to support it properly for those...

[ocaisa]

Since #4031 includes (initial) support for these has been merged I think we can close this