[llvm] [GlobalISel] Fall back for bf16 conversions. (PR #71470)

[Matt Arsenault via llvm-commits]

arsenm wrote:

> Now an error is reported for a very simple bf16 data addition. Is this modification too violent?
> 
> ```
> #include <arm_neon.h>
> bfloat16_t test(bfloat16_t gpara1, bfloat16_t gpara2)
> {
>     return gpara1+gpara2;
> }
> ```

No, this is exactly the kind of case that is supposed to be rejected

https://github.com/llvm/llvm-project/pull/71470