[Bug tree-optimization/116075] Inefficient SVE INSR codegen

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116075

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Short not using the vectorizer testcase:
```
#include <arm_sve.h>

svint8_t f(void)
{
  svint8_t tt;
  tt = svdup_s8 (0);
  tt = svinsr (tt, 0);
  return tt;
}
```

Note LLVM does not optimize the above to just `mov z31.b, #0` either but does
for the original auto-vectorized testcase.