`f16b.rs` fails on LoongArch

[heiher]

I tried this code on LoongArch:

./x.py test

------FileCheck stderr------------------------------                                 
/var/lib/gitlab-runner/builds/la-rs-rust/la-rs/rust/rust/tests/codegen-llvm/float/f16b.rs:11:17: error: CHECK-LABEL: expected string not found in input 
// CHECK-LABEL: define{{.*}} bfloat @identity_f16b(bfloat
...
            6: ; Function Attrs: mustprogress nofree norecurse nosync nounwind willreturn memory(none) uwtable
            7: define half @identity_f16b(half returned %0) unnamed_addr #0 !guid !4 {
label:11'2     ?                                                                         possible intended match
            8: start:                                                           
            9:  ret half %0                                                     
           10: }