tommat01 wrote:
> > Is it possible / would it make sense to directly annotate these noalias in
> > the frontend (i.e. when clang emits the outlined function)?
>
> I hadn't considered that exactly (I tried other frontend fixes) but I think
> it would work for the outlined function case. The main reason for not doing
> it in the frontend was to not repeat the same analysis for flang etc. Also
> (rightly or wrongly) I just had more confidence that Attributor would do the
> alias analysis correctly; there might be some edge cases in the frontend that
> could be missed.
Alias analysis is still necessary because the address of the captured values
might escape before the parallel region:
```
escaped = &value; // address of the slot escapes
#pragma omp parallel
{
opaque(); // might access the slot via escaped pointer
use(value);
}
```
In that case annotating the pointer to `value` with `noalias` would be wrong.
https://github.com/llvm/llvm-project/pull/218453
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