Re: [PATCH 09/15] Hexagon (target/hexagon) use softfloat for float-to-int conversions

[Richard Henderson]

On 3/24/21 8:50 PM, Taylor Simpson wrote:
> @@ -451,16 +456,28 @@ int32_t HELPER(conv_sf2w)(CPUHexagonState *env, float32 
> RsV)
>   {
>       int32_t RdV;
>       arch_fpop_start(env);
> -    RdV = conv_sf_to_4s(RsV, &env->fp_status);
> +    /* Hexagon returns -1 for NaN */
> +    if (float32_is_any_nan(RsV)) {
> +        float_raise(float_flag_invalid, &env->fp_status);
> +        RdV = -1;
> +    } else {
> +        RdV = float32_to_int32(RsV, &env->fp_status);
> +    }

So this is interesting.

The 8.3.x Document Bundle, which has the V67 programmer's manual, say the 
output value is IMPLEMENTATION DEFINED (without saying anything more about 
defining values for any particular implementation), while the older 2010 manual 
specifies 0x7fffffff as the result (which is what float32_to_int32 provides).

I must say I find the newer manual very lacking on details, including the 
non-specification of the Behavior pseudocode functions.

I guess the only thing we can do is document this as matching some particular 
hardware implementation?


r~