incorrect result - batchmode

[ZuseZ4]

rust-lang/rust#152724

The original issue reported there was an incorrect result by Enzyme in debug mode.

I tried to help minimizing but encountered a case where Enzyme creates a segfaulting binary instead:

segfault_causing.ll.txt

Here's a an automatically significantly reduced version. It still prints wrong results and then segfaults, but llvm-reduce could have introduced it's own issues:

reduced.ll.txt

[ZuseZ4]

Both can be compiled by clang-22 on an x86-64 system and have to be executed, the linked rust issue also has some ll files for macos.

[ZuseZ4]

cc @tgymnich If you have a minute, could we please get llvm-22 on the compiler explorer?

relatedly, I tried sharing the (18k LoC) compiler explorer instance, but ran into this error:

[wsmoses]

hm there's a lot of excess code here. A runtime error is harder to debug than a compile time one, can you get it down to the point the primal, and derivative calling conv is readable/understandable why it shouldn't segfault?