From 7616e27c73841ac1e8fa031d843bde1325307bab Mon Sep 17 00:00:00 2001 From: Chih-Min Chao Date: Thu, 30 Jul 2020 02:52:23 -0700 Subject: [PATCH 001/107] softfloat: add APIs to handle alternative sNaN propagation For "fmax/fmin ft0, ft1, ft2" and if one of the inputs is sNaN, The original logic return NaN and set invalid flag if ft1 == sNaN || ft2 == sNan The alternative path set invalid flag if ft1 == sNaN || ft2 == sNaN return NaN if ft1 == sNaN && ft2 == sNaN The ieee754 spec allows both implementation and some architecture such as riscv choose differenct defintion in two spec versions. (riscv-spec-v2.2 use original version, riscv-spec-20191213 changes to alternative) Signed-off-by: Chih-Min Chao Message-Id: <1596102747-20226-3-git-send-email-chihmin.chao@sifive.com> --- fpu/softfloat.c | 92 +++++++++++++++++++++++++---------------- include/fpu/softfloat.h | 6 +++ 2 files changed, 63 insertions(+), 35 deletions(-) diff --git a/fpu/softfloat.c b/fpu/softfloat.c index 67cfa0fd82..edaa760310 100644 --- a/fpu/softfloat.c +++ b/fpu/softfloat.c @@ -894,11 +894,16 @@ static FloatParts return_nan(FloatParts a, float_status *s) return a; } -static FloatParts pick_nan(FloatParts a, FloatParts b, float_status *s) +static void set_snan_flag(FloatParts a, FloatParts b, float_status *s) { if (is_snan(a.cls) || is_snan(b.cls)) { s->float_exception_flags |= float_flag_invalid; } +} + +static FloatParts pick_nan(FloatParts a, FloatParts b, float_status *s) +{ + set_snan_flag(a, b, s); if (s->default_nan_mode) { return parts_default_nan(s); @@ -3091,23 +3096,32 @@ bfloat16 uint16_to_bfloat16(uint16_t a, float_status *status) * and minNumMag() from the IEEE-754 2008. */ static FloatParts minmax_floats(FloatParts a, FloatParts b, bool ismin, - bool ieee, bool ismag, float_status *s) + bool ieee, bool ismag, bool issnan_prop, + float_status *s) { if (unlikely(is_nan(a.cls) || is_nan(b.cls))) { if (ieee) { /* Takes two floating-point values `a' and `b', one of * which is a NaN, and returns the appropriate NaN * result. If either `a' or `b' is a signaling NaN, - * the invalid exception is raised. + * the invalid exception is raised but the NaN + * propagation is 'shall'. */ if (is_snan(a.cls) || is_snan(b.cls)) { - return pick_nan(a, b, s); - } else if (is_nan(a.cls) && !is_nan(b.cls)) { + if (issnan_prop) { + return pick_nan(a, b, s); + } else { + set_snan_flag(a, b, s); + } + } + + if (is_nan(a.cls) && !is_nan(b.cls)) { return b; } else if (is_nan(b.cls) && !is_nan(a.cls)) { return a; } } + return pick_nan(a, b, s); } else { int a_exp, b_exp; @@ -3161,56 +3175,64 @@ static FloatParts minmax_floats(FloatParts a, FloatParts b, bool ismin, } } -#define MINMAX(sz, name, ismin, isiee, ismag) \ +#define MINMAX(sz, name, ismin, isiee, ismag, issnan_prop) \ float ## sz float ## sz ## _ ## name(float ## sz a, float ## sz b, \ float_status *s) \ { \ FloatParts pa = float ## sz ## _unpack_canonical(a, s); \ FloatParts pb = float ## sz ## _unpack_canonical(b, s); \ - FloatParts pr = minmax_floats(pa, pb, ismin, isiee, ismag, s); \ + FloatParts pr = minmax_floats(pa, pb, ismin, isiee, ismag, \ + issnan_prop, s); \ \ return float ## sz ## _round_pack_canonical(pr, s); \ } -MINMAX(16, min, true, false, false) -MINMAX(16, minnum, true, true, false) -MINMAX(16, minnummag, true, true, true) -MINMAX(16, max, false, false, false) -MINMAX(16, maxnum, false, true, false) -MINMAX(16, maxnummag, false, true, true) - -MINMAX(32, min, true, false, false) -MINMAX(32, minnum, true, true, false) -MINMAX(32, minnummag, true, true, true) -MINMAX(32, max, false, false, false) -MINMAX(32, maxnum, false, true, false) -MINMAX(32, maxnummag, false, true, true) - -MINMAX(64, min, true, false, false) -MINMAX(64, minnum, true, true, false) -MINMAX(64, minnummag, true, true, true) -MINMAX(64, max, false, false, false) -MINMAX(64, maxnum, false, true, false) -MINMAX(64, maxnummag, false, true, true) +MINMAX(16, min, true, false, false, true) +MINMAX(16, minnum, true, true, false, true) +MINMAX(16, minnum_noprop, true, true, false, false) +MINMAX(16, minnummag, true, true, true, true) +MINMAX(16, max, false, false, false, true) +MINMAX(16, maxnum, false, true, false, true) +MINMAX(16, maxnum_noprop, false, true, false, false) +MINMAX(16, maxnummag, false, true, true, true) + +MINMAX(32, min, true, false, false, true) +MINMAX(32, minnum, true, true, false, true) +MINMAX(32, minnum_noprop, true, true, false, false) +MINMAX(32, minnummag, true, true, true, true) +MINMAX(32, max, false, false, false, true) +MINMAX(32, maxnum, false, true, false, true) +MINMAX(32, maxnum_noprop, false, true, false, false) +MINMAX(32, maxnummag, false, true, true, true) + +MINMAX(64, min, true, false, false, true) +MINMAX(64, minnum, true, true, false, true) +MINMAX(64, minnum_noprop, true, true, false, false) +MINMAX(64, minnummag, true, true, true, true) +MINMAX(64, max, false, false, false, true) +MINMAX(64, maxnum, false, true, false, true) +MINMAX(64, maxnum_noprop, false, true, false, false) +MINMAX(64, maxnummag, false, true, true, true) #undef MINMAX -#define BF16_MINMAX(name, ismin, isiee, ismag) \ +#define BF16_MINMAX(name, ismin, isiee, ismag, issnan_prop) \ bfloat16 bfloat16_ ## name(bfloat16 a, bfloat16 b, float_status *s) \ { \ FloatParts pa = bfloat16_unpack_canonical(a, s); \ FloatParts pb = bfloat16_unpack_canonical(b, s); \ - FloatParts pr = minmax_floats(pa, pb, ismin, isiee, ismag, s); \ + FloatParts pr = minmax_floats(pa, pb, ismin, isiee, ismag, \ + issnan_prop, s); \ \ return bfloat16_round_pack_canonical(pr, s); \ } -BF16_MINMAX(min, true, false, false) -BF16_MINMAX(minnum, true, true, false) -BF16_MINMAX(minnummag, true, true, true) -BF16_MINMAX(max, false, false, false) -BF16_MINMAX(maxnum, false, true, false) -BF16_MINMAX(maxnummag, false, true, true) +BF16_MINMAX(min, true, false, false, true) +BF16_MINMAX(minnum, true, true, false, true) +BF16_MINMAX(minnummag, true, true, true, true) +BF16_MINMAX(max, false, false, false, true) +BF16_MINMAX(maxnum, false, true, false, true) +BF16_MINMAX(maxnummag, false, true, true, true) #undef BF16_MINMAX diff --git a/include/fpu/softfloat.h b/include/fpu/softfloat.h index 78ad5ca738..5cd7d44bc9 100644 --- a/include/fpu/softfloat.h +++ b/include/fpu/softfloat.h @@ -240,6 +240,8 @@ float16 float16_minnum(float16, float16, float_status *status); float16 float16_maxnum(float16, float16, float_status *status); float16 float16_minnummag(float16, float16, float_status *status); float16 float16_maxnummag(float16, float16, float_status *status); +float16 float16_minnum_noprop(float16, float16, float_status *status); +float16 float16_maxnum_noprop(float16, float16, float_status *status); float16 float16_sqrt(float16, float_status *status); FloatRelation float16_compare(float16, float16, float_status *status); FloatRelation float16_compare_quiet(float16, float16, float_status *status); @@ -586,6 +588,8 @@ float32 float32_minnum(float32, float32, float_status *status); float32 float32_maxnum(float32, float32, float_status *status); float32 float32_minnummag(float32, float32, float_status *status); float32 float32_maxnummag(float32, float32, float_status *status); +float32 float32_minnum_noprop(float32, float32, float_status *status); +float32 float32_maxnum_noprop(float32, float32, float_status *status); bool float32_is_quiet_nan(float32, float_status *status); bool float32_is_signaling_nan(float32, float_status *status); float32 float32_silence_nan(float32, float_status *status); @@ -775,6 +779,8 @@ float64 float64_minnum(float64, float64, float_status *status); float64 float64_maxnum(float64, float64, float_status *status); float64 float64_minnummag(float64, float64, float_status *status); float64 float64_maxnummag(float64, float64, float_status *status); +float64 float64_minnum_noprop(float64, float64, float_status *status); +float64 float64_maxnum_noprop(float64, float64, float_status *status); bool float64_is_quiet_nan(float64 a, float_status *status); bool float64_is_signaling_nan(float64, float_status *status); float64 float64_silence_nan(float64, float_status *status); -- 2.33.1