Commit f131bae8 authored by Emilio G. Cota's avatar Emilio G. Cota Committed by Alex Bennée
Browse files

hardfloat: implement float32/64 square root 



Performance results for fp-bench:

Host: Intel(R) Core(TM) i7-6700K CPU @ 4.00GHz
- before:
sqrt-single: 42.30 MFlops
sqrt-double: 22.97 MFlops
- after:
sqrt-single: 311.42 MFlops
sqrt-double: 311.08 MFlops

Here USE_FP makes a huge difference for f64's, with throughput
going from ~200 MFlops to ~300 MFlops.

Reviewed-by: default avatarAlex Bennée <alex.bennee@linaro.org>
Signed-off-by: default avatarEmilio G. Cota <cota@braap.org>
Signed-off-by: default avatarAlex Bennée <alex.bennee@linaro.org>
parent ccf770ba

fpu/softfloat.c

+58 −2
Original line number Diff line number Diff line
@@ -3044,20 +3044,76 @@ float16 QEMU_FLATTEN float16_sqrt(float16 a, float_status *status) 
    return float16_round_pack_canonical(pr, status);

}



float32 QEMU_FLATTEN float32_sqrt(float32 a, float_status *status)

static float32 QEMU_SOFTFLOAT_ATTR

soft_f32_sqrt(float32 a, float_status *status)

{

    FloatParts pa = float32_unpack_canonical(a, status);

    FloatParts pr = sqrt_float(pa, status, &float32_params);

    return float32_round_pack_canonical(pr, status);

}



float64 QEMU_FLATTEN float64_sqrt(float64 a, float_status *status)

static float64 QEMU_SOFTFLOAT_ATTR

soft_f64_sqrt(float64 a, float_status *status)

{

    FloatParts pa = float64_unpack_canonical(a, status);

    FloatParts pr = sqrt_float(pa, status, &float64_params);

    return float64_round_pack_canonical(pr, status);

}



float32 QEMU_FLATTEN float32_sqrt(float32 xa, float_status *s)

{

    union_float32 ua, ur;



    ua.s = xa;

    if (unlikely(!can_use_fpu(s))) {

        goto soft;

    }



    float32_input_flush1(&ua.s, s);

    if (QEMU_HARDFLOAT_1F32_USE_FP) {

        if (unlikely(!(fpclassify(ua.h) == FP_NORMAL ||

                       fpclassify(ua.h) == FP_ZERO) ||

                     signbit(ua.h))) {

            goto soft;

        }

    } else if (unlikely(!float32_is_zero_or_normal(ua.s) ||

                        float32_is_neg(ua.s))) {

        goto soft;

    }

    ur.h = sqrtf(ua.h);

    return ur.s;



 soft:

    return soft_f32_sqrt(ua.s, s);

}



float64 QEMU_FLATTEN float64_sqrt(float64 xa, float_status *s)

{

    union_float64 ua, ur;



    ua.s = xa;

    if (unlikely(!can_use_fpu(s))) {

        goto soft;

    }



    float64_input_flush1(&ua.s, s);

    if (QEMU_HARDFLOAT_1F64_USE_FP) {

        if (unlikely(!(fpclassify(ua.h) == FP_NORMAL ||

                       fpclassify(ua.h) == FP_ZERO) ||

                     signbit(ua.h))) {

            goto soft;

        }

    } else if (unlikely(!float64_is_zero_or_normal(ua.s) ||

                        float64_is_neg(ua.s))) {

        goto soft;

    }

    ur.h = sqrt(ua.h);

    return ur.s;



 soft:

    return soft_f64_sqrt(ua.s, s);

}



/*----------------------------------------------------------------------------

| The pattern for a default generated NaN.

*----------------------------------------------------------------------------*/