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fpu: Split scalbn from partsN(muladd_scalbn)

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Handle the scaling separately with parts64_scalbn.

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This commit is contained in:
Richard Henderson
2026-04-28 08:01:10 +10:00
parent 333a9d621f
commit 1f5d3cebf0
2 changed files with 34 additions and 23 deletions
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20
fpu/softfloat-parts.c.inc
View File

@@ -669,17 +669,19 @@ static FloatPartsN *partsN(mul)(FloatPartsN *a, FloatPartsN *b,
* `b' then adding 'c', with no intermediate rounding step after the
* multiplication. The operation is performed according to the
* IEC/IEEE Standard for Binary Floating-Point Arithmetic 754-2008.
* The flags argument allows the caller to select negation of the
* addend, the intermediate product, or the final result. (The
* difference between this and having the caller do a separate
* negation is that negating externally will flip the sign bit on NaNs.)
* The flags argument allows the caller to select negation of the addend
* or the intermediate product. (The difference between this and having
* the caller do a separate negation is that negating externally will
* flip the sign bit on NaNs.) Note that float_muladd_negate_result
* is not applied here, and should be handled separately after rounding
* chooses the final sign of 0.0.
*
* Requires A and C extracted into a double-sized structure to provide the
* extra space for the widening multiply.
*/
static FloatPartsN *partsN(muladd_scalbn)(FloatPartsN *a, FloatPartsN *b,
FloatPartsN *c, int scale,
int flags, float_status *s)
static FloatPartsN *partsN(muladd)(FloatPartsN *a, FloatPartsN *b,
FloatPartsN *c,
int flags, float_status *s)
{
int ab_mask, abc_mask;
FloatPartsW p_widen, c_widen;
@@ -725,7 +727,7 @@ static FloatPartsN *partsN(muladd_scalbn)(FloatPartsN *a, FloatPartsN *b,
g_assert(ab_mask & float_cmask_zero);
if (is_anynorm(c->cls)) {
*a = *c;
goto return_normal;
goto finish_sign;
}
if (c->cls == float_class_zero) {
if (flags & float_muladd_suppress_add_product_zero) {
@@ -770,8 +772,6 @@ static FloatPartsN *partsN(muladd_scalbn)(FloatPartsN *a, FloatPartsN *b,
a->sign = p_widen.sign;
a->exp = p_widen.exp;
return_normal:
a->exp += scale;
finish_sign:
/*
* All result types except for "return the default NaN

37
fpu/softfloat.c
View File

@@ -1907,11 +1907,14 @@ float16_muladd_scalbn(float16 a, float16 b, float16 c,
FloatParts64 pa = float16_unpack_canonical(a, status);
FloatParts64 pb = float16_unpack_canonical(b, status);
FloatParts64 pc = float16_unpack_canonical(c, status);
FloatParts64 *pr =
parts64_muladd_scalbn(&pa, &pb, &pc, scale, flags, status);
FloatParts64 *pr = parts64_muladd(&pa, &pb, &pc, flags, status);
/* Round before applying negate result. */
/* Before rounding, scale. */
if (scale) {
parts64_scalbn(pr, scale, status);
}
parts64_uncanon(pr, status, &float16_params, false);
/* After rounding, apply negate result, especially for -0.0. */
if ((flags & float_muladd_negate_result) && !is_nan(pr->cls)) {
pr->sign ^= 1;
}
@@ -1931,10 +1934,14 @@ float32_muladd_scalbn(float32 a, float32 b, float32 c,
FloatParts64 pa = float32_unpack_canonical(a, status);
FloatParts64 pb = float32_unpack_canonical(b, status);
FloatParts64 pc = float32_unpack_canonical(c, status);
FloatParts64 *pr = parts64_muladd_scalbn(&pa, &pb, &pc, scale, flags, status);
FloatParts64 *pr = parts64_muladd(&pa, &pb, &pc, flags, status);
/* Round before applying negate result. */
/* Before rounding, scale. */
if (scale) {
parts64_scalbn(pr, scale, status);
}
parts64_uncanon(pr, status, &float32_params, false);
/* After rounding, apply negate result, especially for -0.0. */
if ((flags & float_muladd_negate_result) && !is_nan(pr->cls)) {
pr->sign ^= 1;
}
@@ -1948,10 +1955,14 @@ float64_muladd_scalbn(float64 a, float64 b, float64 c,
FloatParts64 pa = float64_unpack_canonical(a, status);
FloatParts64 pb = float64_unpack_canonical(b, status);
FloatParts64 pc = float64_unpack_canonical(c, status);
FloatParts64 *pr = parts64_muladd_scalbn(&pa, &pb, &pc, scale, flags, status);
FloatParts64 *pr = parts64_muladd(&pa, &pb, &pc, flags, status);
/* Round before applying negate result. */
/* Before rounding, scale. */
if (scale) {
parts64_scalbn(pr, scale, status);
}
parts64_uncanon(pr, status, &float64_params, false);
/* After rounding, apply negate result, especially for -0.0. */
if ((flags & float_muladd_negate_result) && !is_nan(pr->cls)) {
pr->sign ^= 1;
}
@@ -2105,7 +2116,7 @@ float64 float64r32_muladd(float64 a, float64 b, float64 c,
FloatParts64 pa = float64_unpack_canonical(a, status);
FloatParts64 pb = float64_unpack_canonical(b, status);
FloatParts64 pc = float64_unpack_canonical(c, status);
FloatParts64 *pr = parts64_muladd_scalbn(&pa, &pb, &pc, 0, flags, status);
FloatParts64 *pr = parts64_muladd(&pa, &pb, &pc, flags, status);
/* Round before applying negate result. */
parts64_uncanon(pr, status, &float32_params, false);
@@ -2121,7 +2132,7 @@ bfloat16 QEMU_FLATTEN bfloat16_muladd(bfloat16 a, bfloat16 b, bfloat16 c,
FloatParts64 pa = bfloat16_unpack_canonical(a, status);
FloatParts64 pb = bfloat16_unpack_canonical(b, status);
FloatParts64 pc = bfloat16_unpack_canonical(c, status);
FloatParts64 *pr = parts64_muladd_scalbn(&pa, &pb, &pc, 0, flags, status);
FloatParts64 *pr = parts64_muladd(&pa, &pb, &pc, flags, status);
/* Round before applying negate result. */
parts64_uncanon(pr, status, &bfloat16_params, false);
@@ -2137,7 +2148,7 @@ float128 QEMU_FLATTEN float128_muladd(float128 a, float128 b, float128 c,
FloatParts128 pa = float128_unpack_canonical(a, status);
FloatParts128 pb = float128_unpack_canonical(b, status);
FloatParts128 pc = float128_unpack_canonical(c, status);
FloatParts128 *pr = parts128_muladd_scalbn(&pa, &pb, &pc, 0, flags, status);
FloatParts128 *pr = parts128_muladd(&pa, &pb, &pc, flags, status);
/* Round before applying negate result. */
parts128_uncanon(pr, status, &float128_params, false);
@@ -5116,7 +5127,7 @@ float32 float32_exp2(float32 a, float_status *status)
rp = float64_unpack_canonical(float64_one, status);
for (int i = 0; i < 15; i++) {
tp = float64_unpack_canonical(float32_exp2_coefficients[i], status);
rp = *parts64_muladd_scalbn(&tp, &xnp, &rp, 0, 0, status);
rp = *parts64_muladd(&tp, &xnp, &rp, 0, status);
xnp = *parts64_mul(&xnp, &xp, status);
}
@@ -5196,8 +5207,8 @@ static void parts_s390_divide_to_integer(FloatParts64 *a, FloatParts64 *b,
/* Compute precise remainder */
r_precise_buf = *b;
r_precise = parts64_muladd_scalbn(&r_precise_buf, n, a, 0,
float_muladd_negate_product, status);
r_precise = parts64_muladd(&r_precise_buf, n, a,
float_muladd_negate_product, status);
/* Round remainder to the target format */
*r = *r_precise;