Re: [RFC PATCH] softfloat: use QEMU_FLATTEN to avoid mistaken isra inlining

[Paolo Bonzini]

On 5/23/23 16:33, Richard Henderson wrote:
> The tests are poorly ordered, testing many unlikely things before the 
> most likely thing (normal).  A better ordering would be
>
>      if (likely(tp##_is_normal(arg))) {
>      } else if (tp##_is_zero(arg)) {
>      } else if (tp##_is_zero_or_denormal(arg)) {
>      } else if (tp##_is_infinity(arg)) {
>      } else {
>          // nan case
>      }

Might also benefit from a is_finite (true if zero or normal or denormal) 
predicate, to do

if (tp##_is_finite(arg)) {
    if (!tp##_is_zero_or_denormal(arg)) {
       // normal
    } else if (tp##_is_zero(arg)) {
    } else {
       // denormal
    }
} else if (tp##_is_infinity(arg)) {
} else {
    // nan
}

since is_normal is a bit more complex and inefficient than the others. 
The compiler should easily reuse the result of masking away the sign bit.

Paolo