diff options
| -rw-r--r-- | fpu/softfloat-parts.c.inc | 148 | ||||
| -rw-r--r-- | fpu/softfloat.c | 199 |
2 files changed, 192 insertions, 155 deletions
diff --git a/fpu/softfloat-parts.c.inc b/fpu/softfloat-parts.c.inc index 25bf99bd0f..efdc724770 100644 --- a/fpu/softfloat-parts.c.inc +++ b/fpu/softfloat-parts.c.inc @@ -133,3 +133,151 @@ static void partsN(canonicalize)(FloatPartsN *p, float_status *status, ? float_class_snan : float_class_qnan); } } + +/* + * Round and uncanonicalize a floating-point number by parts. There + * are FRAC_SHIFT bits that may require rounding at the bottom of the + * fraction; these bits will be removed. The exponent will be biased + * by EXP_BIAS and must be bounded by [EXP_MAX-1, 0]. + */ +static void partsN(uncanon)(FloatPartsN *p, float_status *s, + const FloatFmt *fmt) +{ + const int exp_max = fmt->exp_max; + const int frac_shift = fmt->frac_shift; + const uint64_t frac_lsb = fmt->frac_lsb; + const uint64_t frac_lsbm1 = fmt->frac_lsbm1; + const uint64_t round_mask = fmt->round_mask; + const uint64_t roundeven_mask = fmt->roundeven_mask; + uint64_t inc; + bool overflow_norm; + int exp, flags = 0; + + if (unlikely(p->cls != float_class_normal)) { + switch (p->cls) { + case float_class_zero: + p->exp = 0; + frac_clear(p); + return; + case float_class_inf: + g_assert(!fmt->arm_althp); + p->exp = fmt->exp_max; + frac_clear(p); + return; + case float_class_qnan: + case float_class_snan: + g_assert(!fmt->arm_althp); + p->exp = fmt->exp_max; + frac_shr(p, fmt->frac_shift); + return; + default: + break; + } + g_assert_not_reached(); + } + + switch (s->float_rounding_mode) { + case float_round_nearest_even: + overflow_norm = false; + inc = ((p->frac_lo & roundeven_mask) != frac_lsbm1 ? frac_lsbm1 : 0); + break; + case float_round_ties_away: + overflow_norm = false; + inc = frac_lsbm1; + break; + case float_round_to_zero: + overflow_norm = true; + inc = 0; + break; + case float_round_up: + inc = p->sign ? 0 : round_mask; + overflow_norm = p->sign; + break; + case float_round_down: + inc = p->sign ? round_mask : 0; + overflow_norm = !p->sign; + break; + case float_round_to_odd: + overflow_norm = true; + inc = p->frac_lo & frac_lsb ? 0 : round_mask; + break; + default: + g_assert_not_reached(); + } + + exp = p->exp + fmt->exp_bias; + if (likely(exp > 0)) { + if (p->frac_lo & round_mask) { + flags |= float_flag_inexact; + if (frac_addi(p, p, inc)) { + frac_shr(p, 1); + p->frac_hi |= DECOMPOSED_IMPLICIT_BIT; + exp++; + } + } + frac_shr(p, frac_shift); + + if (fmt->arm_althp) { + /* ARM Alt HP eschews Inf and NaN for a wider exponent. */ + if (unlikely(exp > exp_max)) { + /* Overflow. Return the maximum normal. */ + flags = float_flag_invalid; + exp = exp_max; + frac_allones(p); + } + } else if (unlikely(exp >= exp_max)) { + flags |= float_flag_overflow | float_flag_inexact; + if (overflow_norm) { + exp = exp_max - 1; + frac_allones(p); + } else { + p->cls = float_class_inf; + exp = exp_max; + frac_clear(p); + } + } + } else if (s->flush_to_zero) { + flags |= float_flag_output_denormal; + p->cls = float_class_zero; + exp = 0; + frac_clear(p); + } else { + bool is_tiny = s->tininess_before_rounding || exp < 0; + + if (!is_tiny) { + FloatPartsN discard; + is_tiny = !frac_addi(&discard, p, inc); + } + + frac_shrjam(p, 1 - exp); + + if (p->frac_lo & round_mask) { + /* Need to recompute round-to-even/round-to-odd. */ + switch (s->float_rounding_mode) { + case float_round_nearest_even: + inc = ((p->frac_lo & roundeven_mask) != frac_lsbm1 + ? frac_lsbm1 : 0); + break; + case float_round_to_odd: + inc = p->frac_lo & frac_lsb ? 0 : round_mask; + break; + default: + break; + } + flags |= float_flag_inexact; + frac_addi(p, p, inc); + } + + exp = (p->frac_hi & DECOMPOSED_IMPLICIT_BIT) != 0; + frac_shr(p, frac_shift); + + if (is_tiny && (flags & float_flag_inexact)) { + flags |= float_flag_underflow; + } + if (exp == 0 && frac_eqz(p)) { + p->cls = float_class_zero; + } + } + p->exp = exp; + float_raise(flags, s); +} diff --git a/fpu/softfloat.c b/fpu/softfloat.c index 535261db44..817a91de85 100644 --- a/fpu/softfloat.c +++ b/fpu/softfloat.c @@ -741,6 +741,14 @@ static void parts128_canonicalize(FloatParts128 *p, float_status *status, #define parts_canonicalize(A, S, F) \ PARTS_GENERIC_64_128(canonicalize, A)(A, S, F) +static void parts64_uncanon(FloatParts64 *p, float_status *status, + const FloatFmt *fmt); +static void parts128_uncanon(FloatParts128 *p, float_status *status, + const FloatFmt *fmt); + +#define parts_uncanon(A, S, F) \ + PARTS_GENERIC_64_128(uncanon, A)(A, S, F) + /* * Helper functions for softfloat-parts.c.inc, per-size operations. */ @@ -748,6 +756,31 @@ static void parts128_canonicalize(FloatParts128 *p, float_status *status, #define FRAC_GENERIC_64_128(NAME, P) \ QEMU_GENERIC(P, (FloatParts128 *, frac128_##NAME), frac64_##NAME) +static bool frac64_addi(FloatParts64 *r, FloatParts64 *a, uint64_t c) +{ + return uadd64_overflow(a->frac, c, &r->frac); +} + +static bool frac128_addi(FloatParts128 *r, FloatParts128 *a, uint64_t c) +{ + c = uadd64_overflow(a->frac_lo, c, &r->frac_lo); + return uadd64_overflow(a->frac_hi, c, &r->frac_hi); +} + +#define frac_addi(R, A, C) FRAC_GENERIC_64_128(addi, R)(R, A, C) + +static void frac64_allones(FloatParts64 *a) +{ + a->frac = -1; +} + +static void frac128_allones(FloatParts128 *a) +{ + a->frac_hi = a->frac_lo = -1; +} + +#define frac_allones(A) FRAC_GENERIC_64_128(allones, A)(A) + static int frac64_cmp(FloatParts64 *a, FloatParts64 *b) { return a->frac == b->frac ? 0 : a->frac < b->frac ? -1 : 1; @@ -846,161 +879,17 @@ static void frac128_shr(FloatParts128 *a, int c) #define frac_shr(A, C) FRAC_GENERIC_64_128(shr, A)(A, C) - -/* Round and uncanonicalize a floating-point number by parts. There - * are FRAC_SHIFT bits that may require rounding at the bottom of the - * fraction; these bits will be removed. The exponent will be biased - * by EXP_BIAS and must be bounded by [EXP_MAX-1, 0]. - */ - -static FloatParts64 round_canonical(FloatParts64 p, float_status *s, - const FloatFmt *parm) +static void frac64_shrjam(FloatParts64 *a, int c) { - const uint64_t frac_lsb = parm->frac_lsb; - const uint64_t frac_lsbm1 = parm->frac_lsbm1; - const uint64_t round_mask = parm->round_mask; - const uint64_t roundeven_mask = parm->roundeven_mask; - const int exp_max = parm->exp_max; - const int frac_shift = parm->frac_shift; - uint64_t frac, inc; - int exp, flags = 0; - bool overflow_norm; - - frac = p.frac; - exp = p.exp; - - switch (p.cls) { - case float_class_normal: - switch (s->float_rounding_mode) { - case float_round_nearest_even: - overflow_norm = false; - inc = ((frac & roundeven_mask) != frac_lsbm1 ? frac_lsbm1 : 0); - break; - case float_round_ties_away: - overflow_norm = false; - inc = frac_lsbm1; - break; - case float_round_to_zero: - overflow_norm = true; - inc = 0; - break; - case float_round_up: - inc = p.sign ? 0 : round_mask; - overflow_norm = p.sign; - break; - case float_round_down: - inc = p.sign ? round_mask : 0; - overflow_norm = !p.sign; - break; - case float_round_to_odd: - overflow_norm = true; - inc = frac & frac_lsb ? 0 : round_mask; - break; - default: - g_assert_not_reached(); - } - - exp += parm->exp_bias; - if (likely(exp > 0)) { - if (frac & round_mask) { - flags |= float_flag_inexact; - if (uadd64_overflow(frac, inc, &frac)) { - frac = (frac >> 1) | DECOMPOSED_IMPLICIT_BIT; - exp++; - } - } - frac >>= frac_shift; - - if (parm->arm_althp) { - /* ARM Alt HP eschews Inf and NaN for a wider exponent. */ - if (unlikely(exp > exp_max)) { - /* Overflow. Return the maximum normal. */ - flags = float_flag_invalid; - exp = exp_max; - frac = -1; - } - } else if (unlikely(exp >= exp_max)) { - flags |= float_flag_overflow | float_flag_inexact; - if (overflow_norm) { - exp = exp_max - 1; - frac = -1; - } else { - p.cls = float_class_inf; - goto do_inf; - } - } - } else if (s->flush_to_zero) { - flags |= float_flag_output_denormal; - p.cls = float_class_zero; - goto do_zero; - } else { - bool is_tiny = s->tininess_before_rounding || (exp < 0); - - if (!is_tiny) { - uint64_t discard; - is_tiny = !uadd64_overflow(frac, inc, &discard); - } - - shift64RightJamming(frac, 1 - exp, &frac); - if (frac & round_mask) { - /* Need to recompute round-to-even. */ - switch (s->float_rounding_mode) { - case float_round_nearest_even: - inc = ((frac & roundeven_mask) != frac_lsbm1 - ? frac_lsbm1 : 0); - break; - case float_round_to_odd: - inc = frac & frac_lsb ? 0 : round_mask; - break; - default: - break; - } - flags |= float_flag_inexact; - frac += inc; - } - - exp = (frac & DECOMPOSED_IMPLICIT_BIT ? 1 : 0); - frac >>= frac_shift; - - if (is_tiny && (flags & float_flag_inexact)) { - flags |= float_flag_underflow; - } - if (exp == 0 && frac == 0) { - p.cls = float_class_zero; - } - } - break; - - case float_class_zero: - do_zero: - exp = 0; - frac = 0; - break; - - case float_class_inf: - do_inf: - assert(!parm->arm_althp); - exp = exp_max; - frac = 0; - break; - - case float_class_qnan: - case float_class_snan: - assert(!parm->arm_althp); - exp = exp_max; - frac >>= parm->frac_shift; - break; - - default: - g_assert_not_reached(); - } + shift64RightJamming(a->frac, c, &a->frac); +} - float_raise(flags, s); - p.exp = exp; - p.frac = frac; - return p; +static void frac128_shrjam(FloatParts128 *a, int c) +{ + shift128RightJamming(a->frac_hi, a->frac_lo, c, &a->frac_hi, &a->frac_lo); } +#define frac_shrjam(A, C) FRAC_GENERIC_64_128(shrjam, A)(A, C) #define partsN(NAME) parts64_##NAME #define FloatPartsN FloatParts64 @@ -1045,7 +934,7 @@ static float16 float16a_round_pack_canonical(FloatParts64 *p, float_status *s, const FloatFmt *params) { - *p = round_canonical(*p, s, params); + parts_uncanon(p, s, params); return float16_pack_raw(p); } @@ -1058,7 +947,7 @@ static float16 float16_round_pack_canonical(FloatParts64 *p, static bfloat16 bfloat16_round_pack_canonical(FloatParts64 *p, float_status *s) { - *p = round_canonical(*p, s, &bfloat16_params); + parts_uncanon(p, s, &bfloat16_params); return bfloat16_pack_raw(p); } @@ -1072,7 +961,7 @@ static void float32_unpack_canonical(FloatParts64 *p, float32 f, static float32 float32_round_pack_canonical(FloatParts64 *p, float_status *s) { - *p = round_canonical(*p, s, &float32_params); + parts_uncanon(p, s, &float32_params); return float32_pack_raw(p); } @@ -1086,7 +975,7 @@ static void float64_unpack_canonical(FloatParts64 *p, float64 f, static float64 float64_round_pack_canonical(FloatParts64 *p, float_status *s) { - *p = round_canonical(*p, s, &float64_params); + parts_uncanon(p, s, &float64_params); return float64_pack_raw(p); } |