Handle the scaling separately with parts64_scalbn.
Reviewed-by: Philippe Mathieu-Daudé <[email protected]>
Signed-off-by: Richard Henderson <[email protected]>
---
fpu/softfloat.c | 37 ++++++++++++++++++++++++-------------
fpu/softfloat-parts.c.inc | 20 ++++++++++----------
2 files changed, 34 insertions(+), 23 deletions(-)
diff --git a/fpu/softfloat.c b/fpu/softfloat.c
index 0a8da13e01..962528cb73 100644
--- a/fpu/softfloat.c
+++ b/fpu/softfloat.c
@@ -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;
diff --git a/fpu/softfloat-parts.c.inc b/fpu/softfloat-parts.c.inc
index 028c2daa27..b8baaf1e76 100644
--- a/fpu/softfloat-parts.c.inc
+++ b/fpu/softfloat-parts.c.inc
@@ -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
--
2.43.0
