tensor indexing fails for llvm 19.1 and 18.1

e.g.

```
a_i { 0.0, 1.0, 2.0, 3.0 }
r_i { a_i[1:3] }
```

results in the error:

```
LLVM ERROR: Instruction Combining did not reach a fixpoint after 1 iterations
```

This is only for LLVM 19.1 and 18.1 that I've seen so far