Lukas Petr

I have tried to build `4.18.0-305.el8` and it seems that you are correct.

I looked at this and it looks like: - When using the standard dev shell (`nix develop`) for both downloading (with `rhel-kernel-get` script) and building the mentioned kernels (`diffkemp build-kernel`)...

Solved by #372 (detects if some configs are missing and exits with error message).

The problem was not encountered when trying it in normal Fedora (not in docker).

It looks like it will probably not be possible to use `-O2`. I [changed `build-kernel`](https://github.com/PLukas2018/diffkemp/commit/b0faed3915533572c4b992505085adcba56d639b) to use `-O2` and to not use custom passes (run `opt`). For the regression (pytest)...

> * `build-kernel` uses `-O1 -Xclang -disable-llvm-passes` and then applies custom passes by running opt (see [kernel_llvm_source_builder.py:412](https://github.com/viktormalik/diffkemp/blob/master/diffkemp/llvm_ir/kernel_llvm_source_builder.py#L412)). It originally used `-O0` but [91f72dd](https://github.com/viktormalik/diffkemp/commit/91f72dd76d4b6712c887bad3b03691995cee2cf2) changed that b/c of LLVM 5.0. We...

I have started to work on the unification of program compilation in the `build`/`build-kernel` command. I have one question (@viktormalik , @lenticularis39 ), do we want to keep using RPython...

Thank you both for your responses. I have tried [Cython](https://cython.readthedocs.io/en/latest/index.html), [Nuitka](https://github.com/Nuitka/Nuitka) and [Mypyc](https://mypyc.readthedocs.io/en/latest/introduction.html) so far I was unsuccessful in getting much better performance than Python has, so I am leaving...

> It looks like it is not possible to get back to `-O0` because then the passes (eg. `mem2reg`) do not work and the tests do not pass. I do...

> I don't think that we rely on the `tbaa` metadata at all. Could you point me to the cases which are failing? It does not have to be necessary...