Commit 2dfabc86 authored by Emilio G. Cota's avatar Emilio G. Cota Committed by Alex Bennée
Browse files

hardfloat: implement float32/64 multiplication 



Performance results for fp-bench:

1. Intel(R) Core(TM) i7-6700K CPU @ 4.00GHz
- before:
mul-single: 126.91 MFlops
mul-double: 118.28 MFlops
- after:
mul-single: 258.02 MFlops
mul-double: 197.96 MFlops

2. ARM Aarch64 A57 @ 2.4GHz
- before:
mul-single: 37.42 MFlops
mul-double: 38.77 MFlops
- after:
mul-single: 73.41 MFlops
mul-double: 76.93 MFlops

3. IBM POWER8E @ 2.1 GHz
- before:
mul-single: 58.40 MFlops
mul-double: 59.33 MFlops
- after:
mul-single: 60.25 MFlops
mul-double: 94.79 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 1b615d48

fpu/softfloat.c

+52 −2
Original line number Diff line number Diff line
@@ -1236,7 +1236,8 @@ float16 QEMU_FLATTEN float16_mul(float16 a, float16 b, float_status *status) 
    return float16_round_pack_canonical(pr, status);

}



float32 QEMU_FLATTEN float32_mul(float32 a, float32 b, float_status *status)

static float32 QEMU_SOFTFLOAT_ATTR

soft_f32_mul(float32 a, float32 b, float_status *status)

{

    FloatParts pa = float32_unpack_canonical(a, status);

    FloatParts pb = float32_unpack_canonical(b, status);
@@ -1245,7 +1246,8 @@ float32 QEMU_FLATTEN float32_mul(float32 a, float32 b, float_status *status) 
    return float32_round_pack_canonical(pr, status);

}



float64 QEMU_FLATTEN float64_mul(float64 a, float64 b, float_status *status)

static float64 QEMU_SOFTFLOAT_ATTR

soft_f64_mul(float64 a, float64 b, float_status *status)

{

    FloatParts pa = float64_unpack_canonical(a, status);

    FloatParts pb = float64_unpack_canonical(b, status);
@@ -1254,6 +1256,54 @@ float64 QEMU_FLATTEN float64_mul(float64 a, float64 b, float_status *status) 
    return float64_round_pack_canonical(pr, status);

}



static float hard_f32_mul(float a, float b)

{

    return a * b;

}



static double hard_f64_mul(double a, double b)

{

    return a * b;

}



static bool f32_mul_fast_test(union_float32 a, union_float32 b)

{

    return float32_is_zero(a.s) || float32_is_zero(b.s);

}



static bool f64_mul_fast_test(union_float64 a, union_float64 b)

{

    return float64_is_zero(a.s) || float64_is_zero(b.s);

}



static float32 f32_mul_fast_op(float32 a, float32 b, float_status *s)

{

    bool signbit = float32_is_neg(a) ^ float32_is_neg(b);



    return float32_set_sign(float32_zero, signbit);

}



static float64 f64_mul_fast_op(float64 a, float64 b, float_status *s)

{

    bool signbit = float64_is_neg(a) ^ float64_is_neg(b);



    return float64_set_sign(float64_zero, signbit);

}



float32 QEMU_FLATTEN

float32_mul(float32 a, float32 b, float_status *s)

{

    return float32_gen2(a, b, s, hard_f32_mul, soft_f32_mul,

                        f32_is_zon2, NULL, f32_mul_fast_test, f32_mul_fast_op);

}



float64 QEMU_FLATTEN

float64_mul(float64 a, float64 b, float_status *s)

{

    return float64_gen2(a, b, s, hard_f64_mul, soft_f64_mul,

                        f64_is_zon2, NULL, f64_mul_fast_test, f64_mul_fast_op);

}



/*

 * Returns the result of multiplying the floating-point values `a' and

 * `b' then adding 'c', with no intermediate rounding step after the