From 1b615d482094e0123d187f0ad3c676ba8eb9d0a3 Mon Sep 17 00:00:00 2001 From: "Emilio G. Cota" Date: Fri, 16 Mar 2018 19:58:42 -0400 Subject: [PATCH] hardfloat: implement float32/64 addition and subtraction MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Performance results (single and double precision) for fp-bench: 1. Intel(R) Core(TM) i7-6700K CPU @ 4.00GHz - before: add-single: 135.07 MFlops add-double: 131.60 MFlops sub-single: 130.04 MFlops sub-double: 133.01 MFlops - after: add-single: 443.04 MFlops add-double: 301.95 MFlops sub-single: 411.36 MFlops sub-double: 293.15 MFlops 2. ARM Aarch64 A57 @ 2.4GHz - before: add-single: 44.79 MFlops add-double: 49.20 MFlops sub-single: 44.55 MFlops sub-double: 49.06 MFlops - after: add-single: 93.28 MFlops add-double: 88.27 MFlops sub-single: 91.47 MFlops sub-double: 88.27 MFlops 3. IBM POWER8E @ 2.1 GHz - before: add-single: 72.59 MFlops add-double: 72.27 MFlops sub-single: 75.33 MFlops sub-double: 70.54 MFlops - after: add-single: 112.95 MFlops add-double: 201.11 MFlops sub-single: 116.80 MFlops sub-double: 188.72 MFlops Note that the IBM and ARM machines benefit from having HARDFLOAT_2F{32,64}_USE_FP set to 0. Otherwise their performance can suffer significantly: - IBM Power8: add-single: [1] 54.94 vs [0] 116.37 MFlops add-double: [1] 58.92 vs [0] 201.44 MFlops - Aarch64 A57: add-single: [1] 80.72 vs [0] 93.24 MFlops add-double: [1] 82.10 vs [0] 88.18 MFlops On the Intel machine, having 2F64 set to 1 pays off, but it doesn't for 2F32: - Intel i7-6700K: add-single: [1] 285.79 vs [0] 426.70 MFlops add-double: [1] 302.15 vs [0] 278.82 MFlops Reviewed-by: Alex Bennée Signed-off-by: Emilio G. Cota Signed-off-by: Alex Bennée --- fpu/softfloat.c | 117 ++++++++++++++++++++++++++++++++++++++++-------- 1 file changed, 98 insertions(+), 19 deletions(-) diff --git a/fpu/softfloat.c b/fpu/softfloat.c index 468c4554d5..08afa861a7 100644 --- a/fpu/softfloat.c +++ b/fpu/softfloat.c @@ -1054,49 +1054,128 @@ float16 QEMU_FLATTEN float16_add(float16 a, float16 b, float_status *status) return float16_round_pack_canonical(pr, status); } -float32 QEMU_FLATTEN float32_add(float32 a, float32 b, float_status *status) +float16 QEMU_FLATTEN float16_sub(float16 a, float16 b, float_status *status) +{ + FloatParts pa = float16_unpack_canonical(a, status); + FloatParts pb = float16_unpack_canonical(b, status); + FloatParts pr = addsub_floats(pa, pb, true, status); + + return float16_round_pack_canonical(pr, status); +} + +static float32 QEMU_SOFTFLOAT_ATTR +soft_f32_addsub(float32 a, float32 b, bool subtract, float_status *status) { FloatParts pa = float32_unpack_canonical(a, status); FloatParts pb = float32_unpack_canonical(b, status); - FloatParts pr = addsub_floats(pa, pb, false, status); + FloatParts pr = addsub_floats(pa, pb, subtract, status); return float32_round_pack_canonical(pr, status); } -float64 QEMU_FLATTEN float64_add(float64 a, float64 b, float_status *status) +static inline float32 soft_f32_add(float32 a, float32 b, float_status *status) +{ + return soft_f32_addsub(a, b, false, status); +} + +static inline float32 soft_f32_sub(float32 a, float32 b, float_status *status) +{ + return soft_f32_addsub(a, b, true, status); +} + +static float64 QEMU_SOFTFLOAT_ATTR +soft_f64_addsub(float64 a, float64 b, bool subtract, float_status *status) { FloatParts pa = float64_unpack_canonical(a, status); FloatParts pb = float64_unpack_canonical(b, status); - FloatParts pr = addsub_floats(pa, pb, false, status); + FloatParts pr = addsub_floats(pa, pb, subtract, status); return float64_round_pack_canonical(pr, status); } -float16 QEMU_FLATTEN float16_sub(float16 a, float16 b, float_status *status) +static inline float64 soft_f64_add(float64 a, float64 b, float_status *status) { - FloatParts pa = float16_unpack_canonical(a, status); - FloatParts pb = float16_unpack_canonical(b, status); - FloatParts pr = addsub_floats(pa, pb, true, status); + return soft_f64_addsub(a, b, false, status); +} - return float16_round_pack_canonical(pr, status); +static inline float64 soft_f64_sub(float64 a, float64 b, float_status *status) +{ + return soft_f64_addsub(a, b, true, status); } -float32 QEMU_FLATTEN float32_sub(float32 a, float32 b, float_status *status) +static float hard_f32_add(float a, float b) { - FloatParts pa = float32_unpack_canonical(a, status); - FloatParts pb = float32_unpack_canonical(b, status); - FloatParts pr = addsub_floats(pa, pb, true, status); + return a + b; +} - return float32_round_pack_canonical(pr, status); +static float hard_f32_sub(float a, float b) +{ + return a - b; } -float64 QEMU_FLATTEN float64_sub(float64 a, float64 b, float_status *status) +static double hard_f64_add(double a, double b) { - FloatParts pa = float64_unpack_canonical(a, status); - FloatParts pb = float64_unpack_canonical(b, status); - FloatParts pr = addsub_floats(pa, pb, true, status); + return a + b; +} - return float64_round_pack_canonical(pr, status); +static double hard_f64_sub(double a, double b) +{ + return a - b; +} + +static bool f32_addsub_post(union_float32 a, union_float32 b) +{ + if (QEMU_HARDFLOAT_2F32_USE_FP) { + return !(fpclassify(a.h) == FP_ZERO && fpclassify(b.h) == FP_ZERO); + } + return !(float32_is_zero(a.s) && float32_is_zero(b.s)); +} + +static bool f64_addsub_post(union_float64 a, union_float64 b) +{ + if (QEMU_HARDFLOAT_2F64_USE_FP) { + return !(fpclassify(a.h) == FP_ZERO && fpclassify(b.h) == FP_ZERO); + } else { + return !(float64_is_zero(a.s) && float64_is_zero(b.s)); + } +} + +static float32 float32_addsub(float32 a, float32 b, float_status *s, + hard_f32_op2_fn hard, soft_f32_op2_fn soft) +{ + return float32_gen2(a, b, s, hard, soft, + f32_is_zon2, f32_addsub_post, NULL, NULL); +} + +static float64 float64_addsub(float64 a, float64 b, float_status *s, + hard_f64_op2_fn hard, soft_f64_op2_fn soft) +{ + return float64_gen2(a, b, s, hard, soft, + f64_is_zon2, f64_addsub_post, NULL, NULL); +} + +float32 QEMU_FLATTEN +float32_add(float32 a, float32 b, float_status *s) +{ + return float32_addsub(a, b, s, hard_f32_add, soft_f32_add); +} + +float32 QEMU_FLATTEN +float32_sub(float32 a, float32 b, float_status *s) +{ + return float32_addsub(a, b, s, hard_f32_sub, soft_f32_sub); +} + +float64 QEMU_FLATTEN +float64_add(float64 a, float64 b, float_status *s) +{ + return float64_addsub(a, b, s, hard_f64_add, soft_f64_add); +} + +float64 QEMU_FLATTEN +float64_sub(float64 a, float64 b, float_status *s) +{ + return float64_addsub(a, b, s, hard_f64_sub, soft_f64_sub); } /* -- GitLab