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[2003:d8:2f38:2400:62f4:c5fa:ba13:ac32]) by smtp.gmail.com with ESMTPSA id h13sm15458550wml.26.2021.05.26.06.45.48 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 26 May 2021 06:45:48 -0700 (PDT) Subject: Re: [PATCH v2 04/28] softfloat: Move minmax_flags to softfloat-parts.c.inc To: Richard Henderson , qemu-devel@nongnu.org References: <20210525150706.294968-1-richard.henderson@linaro.org> <20210525150706.294968-5-richard.henderson@linaro.org> From: David Hildenbrand Organization: Red Hat Message-ID: <34c1da32-3c06-47a7-a9d8-d9668a63e70d@redhat.com> Date: Wed, 26 May 2021 15:45:47 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.10.1 MIME-Version: 1.0 In-Reply-To: <20210525150706.294968-5-richard.henderson@linaro.org> Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=david@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=216.205.24.124; envelope-from=david@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -31 X-Spam_score: -3.2 X-Spam_bar: --- X-Spam_report: (-3.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.371, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.001, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: alex.bennee@linaro.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 25.05.21 17:06, Richard Henderson wrote: > Rename to parts$N_minmax. Combine 3 bool arguments to a bitmask, > return a tri-state value to indicate nan vs unchanged operand. > Introduce ftype_minmax functions as a common optimization point. > Fold bfloat16 expansions into the same macro as the other types. > > Signed-off-by: Richard Henderson > --- > fpu/softfloat.c | 216 ++++++++++++++++---------------------- > fpu/softfloat-parts.c.inc | 81 ++++++++++++++ > 2 files changed, 170 insertions(+), 127 deletions(-) > > diff --git a/fpu/softfloat.c b/fpu/softfloat.c > index db14bd09aa..2dadded0b5 100644 > --- a/fpu/softfloat.c > +++ b/fpu/softfloat.c > @@ -482,6 +482,15 @@ enum { > float_cmask_anynan = float_cmask_qnan | float_cmask_snan, > }; > > +/* Flags for parts_minmax. */ > +enum { > + /* Set for minimum; clear for maximum. */ > + minmax_ismin = 1, > + /* Set for the IEEE 754-2008 minNum() and maxNum() operations. */ > + minmax_isnum = 2, > + /* Set for the IEEE 754-2008 minNumMag() and minNumMag() operations. */ > + minmax_ismag = 4, > +}; > > /* Simple helpers for checking if, or what kind of, NaN we have */ > static inline __attribute__((unused)) bool is_nan(FloatClass c) > @@ -865,6 +874,14 @@ static void parts128_uint_to_float(FloatParts128 *p, uint64_t a, > #define parts_uint_to_float(P, I, Z, S) \ > PARTS_GENERIC_64_128(uint_to_float, P)(P, I, Z, S) > > +static int parts64_minmax(FloatParts64 *a, FloatParts64 *b, > + float_status *s, int flags, const FloatFmt *fmt); > +static int parts128_minmax(FloatParts128 *a, FloatParts128 *b, > + float_status *s, int flags, const FloatFmt *fmt); > + > +#define parts_minmax(A, B, S, Z, F) \ > + PARTS_GENERIC_64_128(minmax, A)(A, B, S, Z, F) > + > /* > * Helper functions for softfloat-parts.c.inc, per-size operations. > */ > @@ -3258,145 +3275,90 @@ float128 uint64_to_float128(uint64_t a, float_status *status) > return float128_round_pack_canonical(&p, status); > } > > -/* Float Min/Max */ > -/* min() and max() functions. These can't be implemented as > - * 'compare and pick one input' because that would mishandle > - * NaNs and +0 vs -0. > - * > - * minnum() and maxnum() functions. These are similar to the min() > - * and max() functions but if one of the arguments is a QNaN and > - * the other is numerical then the numerical argument is returned. > - * SNaNs will get quietened before being returned. > - * minnum() and maxnum correspond to the IEEE 754-2008 minNum() > - * and maxNum() operations. min() and max() are the typical min/max > - * semantics provided by many CPUs which predate that specification. > - * > - * minnummag() and maxnummag() functions correspond to minNumMag() > - * and minNumMag() from the IEEE-754 2008. > +/* > + * Minimum and maximum > */ > -static FloatParts64 minmax_floats(FloatParts64 a, FloatParts64 b, bool ismin, > - bool ieee, bool ismag, float_status *s) > + > +static float16 float16_minmax(float16 a, float16 b, float_status *s, int flags) > { > - 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. > - */ > - if (is_snan(a.cls) || is_snan(b.cls)) { > - return *parts_pick_nan(&a, &b, s); > - } else if (is_nan(a.cls) && !is_nan(b.cls)) { > - return b; > - } else if (is_nan(b.cls) && !is_nan(a.cls)) { > - return a; > - } > - } > - return *parts_pick_nan(&a, &b, s); > - } else { > - int a_exp, b_exp; > + FloatParts64 pa, pb; > + int which; > > - switch (a.cls) { > - case float_class_normal: > - a_exp = a.exp; > - break; > - case float_class_inf: > - a_exp = INT_MAX; > - break; > - case float_class_zero: > - a_exp = INT_MIN; > - break; > - default: > - g_assert_not_reached(); > - break; > - } > - switch (b.cls) { > - case float_class_normal: > - b_exp = b.exp; > - break; > - case float_class_inf: > - b_exp = INT_MAX; > - break; > - case float_class_zero: > - b_exp = INT_MIN; > - break; > - default: > - g_assert_not_reached(); > - break; > - } > - > - if (ismag && (a_exp != b_exp || a.frac != b.frac)) { > - bool a_less = a_exp < b_exp; > - if (a_exp == b_exp) { > - a_less = a.frac < b.frac; > - } > - return a_less ^ ismin ? b : a; > - } > - > - if (a.sign == b.sign) { > - bool a_less = a_exp < b_exp; > - if (a_exp == b_exp) { > - a_less = a.frac < b.frac; > - } > - return a.sign ^ a_less ^ ismin ? b : a; > - } else { > - return a.sign ^ ismin ? b : a; > - } > + float16_unpack_canonical(&pa, a, s); > + float16_unpack_canonical(&pb, b, s); > + which = parts_minmax(&pa, &pb, s, flags, &float16_params); > + if (unlikely(which < 0)) { > + /* Some sort of nan, need to repack default and silenced nans. */ > + return float16_round_pack_canonical(&pa, s); > } > + return which ? b : a; > } > > -#define MINMAX(sz, name, ismin, isiee, ismag) \ > -float ## sz float ## sz ## _ ## name(float ## sz a, float ## sz b, \ > - float_status *s) \ > -{ \ > - FloatParts64 pa, pb, pr; \ > - float ## sz ## _unpack_canonical(&pa, a, s); \ > - float ## sz ## _unpack_canonical(&pb, b, s); \ > - pr = minmax_floats(pa, pb, ismin, isiee, ismag, s); \ > - return float ## sz ## _round_pack_canonical(&pr, s); \ > +static bfloat16 bfloat16_minmax(bfloat16 a, bfloat16 b, > + float_status *s, int flags) > +{ > + FloatParts64 pa, pb; > + int which; > + > + bfloat16_unpack_canonical(&pa, a, s); > + bfloat16_unpack_canonical(&pb, b, s); > + which = parts_minmax(&pa, &pb, s, flags, &float16_params); > + if (unlikely(which < 0)) { > + /* Some sort of nan, need to repack default and silenced nans. */ > + return bfloat16_round_pack_canonical(&pa, s); > + } > + return which ? b : a; > } > > -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) > +static float32 float32_minmax(float32 a, float32 b, float_status *s, int flags) > +{ > + FloatParts64 pa, pb; > + int which; > > -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) > - > -#undef MINMAX > - > -#define BF16_MINMAX(name, ismin, isiee, ismag) \ > -bfloat16 bfloat16_ ## name(bfloat16 a, bfloat16 b, float_status *s) \ > -{ \ > - FloatParts64 pa, pb, pr; \ > - bfloat16_unpack_canonical(&pa, a, s); \ > - bfloat16_unpack_canonical(&pb, b, s); \ > - pr = minmax_floats(pa, pb, ismin, isiee, ismag, s); \ > - return bfloat16_round_pack_canonical(&pr, s); \ > + float32_unpack_canonical(&pa, a, s); > + float32_unpack_canonical(&pb, b, s); > + which = parts_minmax(&pa, &pb, s, flags, &float32_params); > + if (unlikely(which < 0)) { > + /* Some sort of nan, need to repack default and silenced nans. */ > + return float32_round_pack_canonical(&pa, s); > + } > + return which ? b : a; > } > > -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) > +static float64 float64_minmax(float64 a, float64 b, float_status *s, int flags) > +{ > + FloatParts64 pa, pb; > + int which; > > -#undef BF16_MINMAX > + float64_unpack_canonical(&pa, a, s); > + float64_unpack_canonical(&pb, b, s); > + which = parts_minmax(&pa, &pb, s, flags, &float64_params); > + if (unlikely(which < 0)) { > + /* Some sort of nan, need to repack default and silenced nans. */ > + return float64_round_pack_canonical(&pa, s); > + } > + return which ? b : a; > +} > + > +#define MINMAX_1(type, name, flags) \ > + type type##_##name(type a, type b, float_status *s) \ > + { return type##_minmax(a, b, s, flags); } > + > +#define MINMAX_2(type) \ > + MINMAX_1(type, max, 0) \ > + MINMAX_1(type, maxnum, minmax_isnum) \ > + MINMAX_1(type, maxnummag, minmax_isnum | minmax_ismag) \ > + MINMAX_1(type, min, minmax_ismin) \ > + MINMAX_1(type, minnum, minmax_ismin | minmax_isnum) \ > + MINMAX_1(type, minnummag, minmax_ismin | minmax_isnum | minmax_ismag) > + > +MINMAX_2(float16) > +MINMAX_2(bfloat16) > +MINMAX_2(float32) > +MINMAX_2(float64) > + > +#undef MINMAX_1 > +#undef MINMAX_2 > > /* Floating point compare */ > static FloatRelation compare_floats(FloatParts64 a, FloatParts64 b, bool is_quiet, > diff --git a/fpu/softfloat-parts.c.inc b/fpu/softfloat-parts.c.inc > index f3c4f8c8d2..d68ab8fee0 100644 > --- a/fpu/softfloat-parts.c.inc > +++ b/fpu/softfloat-parts.c.inc > @@ -936,3 +936,84 @@ static void partsN(uint_to_float)(FloatPartsN *p, uint64_t a, > p->frac_hi = a << shift; > } > } > + > +/* > + * Float min/max. > + * > + * Return -1 to return the chosen nan in *a; > + * return 0 to use the a input unchanged; 1 to use the b input unchanged. > + */ > +static int partsN(minmax)(FloatPartsN *a, FloatPartsN *b, > + float_status *s, int flags, const FloatFmt *fmt) > +{ > + int ab_mask = float_cmask(a->cls) | float_cmask(b->cls); > + int a_exp, b_exp, cmp; > + > + if (unlikely(ab_mask & float_cmask_anynan)) { > + /* > + * For minnum/maxnum, if one operand is a QNaN, and the other > + * operand is numerical, then return numerical argument. > + */ > + if ((flags & minmax_isnum) > + && !(ab_mask & float_cmask_snan) > + && (ab_mask & ~float_cmask_qnan)) { > + return is_nan(a->cls); > + } > + *a = *parts_pick_nan(a, b, s); > + return -1; > + } > + > + a_exp = a->exp; > + b_exp = b->exp; > + > + if (unlikely(ab_mask != float_cmask_normal)) { > + switch (a->cls) { > + case float_class_normal: > + break; > + case float_class_inf: > + a_exp = INT16_MAX; > + break; > + case float_class_zero: > + a_exp = INT16_MIN; > + break; > + default: > + g_assert_not_reached(); > + break; > + } > + switch (b->cls) { > + case float_class_normal: > + break; > + case float_class_inf: > + b_exp = INT16_MAX; > + break; > + case float_class_zero: > + b_exp = INT16_MIN; > + break; > + default: > + g_assert_not_reached(); > + break; > + } > + } > + > + /* Compare magnitudes. */ > + cmp = a_exp - b_exp; > + if (cmp == 0) { > + cmp = frac_cmp(a, b); > + } > + > + /* > + * Take the sign into account. > + * For ismag, only do this if the magnitudes are equal. > + */ > + if (!(flags & minmax_ismag) || cmp == 0) { > + if (a->sign != b->sign) { > + /* For differing signs, the negative operand is less. */ > + cmp = a->sign ? -1 : 1; > + } else if (a->sign) { > + /* For two negative operands, invert the magnitude comparison. */ > + cmp = -cmp; > + } > + } > + > + return (cmp < 0) ^ !!(flags & minmax_ismin); > +} > Looks good to me Reviewed-by: David Hildenbrand -- Thanks, David / dhildenb