[Bug target/121699] [16 regression] ICE when building mesa-25.1.8 with -march=znver4

[sjames at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121699

--- Comment #1 from Sam James <sjames at gcc dot gnu.org> ---
```
typedef struct
{
  int u32;
} nir_const_value;

nir_const_value *evaluate_prmt_nv__dst_val;

int evaluate_prmt_nv__src_0, evaluate_prmt_nv_src;

void
evaluate_prmt_nv (unsigned num_components)
{
  for (unsigned _i = 0; _i < num_components; _i++)
    {
      char x = evaluate_prmt_nv_src;
      if (evaluate_prmt_nv__src_0)
        x = x >> 7;
      evaluate_prmt_nv__dst_val[_i].u32 = x;
    }
}
```