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

[via llvm-commits]

erickq 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

clang -O0 -march=armv8.2-a+bf16 test.c

I don't really understand that at this point our hardware already supports the bf16 data type.


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