[flang-commits] [flang] [flang][HLFIR] Fix crash in WHERE with exactly_once inside elemental (PR #194443)

[Michael Klemm via flang-commits]

mjklemm wrote:

> It should be `return builder.getRegion().getParentOfType<hlfir::WhereOp>();`.
> 
> Then it is impossible for an hlfir.exactly_once to be nested inside an hlfir.elemental before the parent hlfir.where.

With this, it seems that the problem is shifting and the original Fortran code now gives an error along these lines:

```
     loc("XXXX":xx:y): error: failed to  
     legalize operation 'hlfir.exactly_once': %49 = "hlfir.exactly_once"() ({...}) : () ->                      
     !hlfir.expr<?x!fir.logical<4>>                                                                             
     error: failure in HLFIR bufferization pass
     error: Lowering to LLVM IR failed                                                                          
     loc("XXXX":zz:a): error: cannot be 
     converted to LLVM IR: missing `LLVMTranslationDialectInterface` registration for dialect for op: func.func
     error: failed to create the LLVM module     
```

It seems that even though the update condition is supposed to avoid the nesting, later code-gen still trips over it.

https://github.com/llvm/llvm-project/pull/194443