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fpu/softfloat: re-factor minmax

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Let's do the same re-factor treatment for minmax functions. I still
use the MACRO trick to expand but now all the checking code is common.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
This commit is contained in:
Alex Bennée
2017-12-05 12:36:01 +00:00
parent 0bfc9f1952
commit 8936006707
2 changed files with 126 additions and 107 deletions
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227
fpu/softfloat.c
View File

@@ -1663,6 +1663,126 @@ float64 uint16_to_float64(uint16_t a, float_status *status)
return uint64_to_float64(a, status); return uint64_to_float64(a, 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.
*/
static FloatParts minmax_floats(FloatParts a, FloatParts b, bool ismin,
bool ieee, bool ismag, 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.
*/
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)) {
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;
bool a_sign, b_sign;
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;
}
a_sign = a.sign;
b_sign = b.sign;
if (ismag) {
a_sign = b_sign = 0;
}
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;
}
}
}
#define MINMAX(sz, name, ismin, isiee, ismag) \
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); \
\
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)
#undef MINMAX
/* Multiply A by 2 raised to the power N. */ /* Multiply A by 2 raised to the power N. */
static FloatParts scalbn_decomposed(FloatParts a, int n, float_status *s) static FloatParts scalbn_decomposed(FloatParts a, int n, float_status *s)
{ {
@@ -6912,113 +7032,6 @@ int float128_compare_quiet(float128 a, float128 b, float_status *status)
return float128_compare_internal(a, b, 1, status); return float128_compare_internal(a, b, 1, status);
} }
/* 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.
* 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.
*/
#define MINMAX(s) \
static inline float ## s float ## s ## _minmax(float ## s a, float ## s b, \
int ismin, int isieee, \
int ismag, \
float_status *status) \
{ \
flag aSign, bSign; \
uint ## s ## _t av, bv, aav, abv; \
a = float ## s ## _squash_input_denormal(a, status); \
b = float ## s ## _squash_input_denormal(b, status); \
if (float ## s ## _is_any_nan(a) || \
float ## s ## _is_any_nan(b)) { \
if (isieee) { \
if (float ## s ## _is_quiet_nan(a, status) && \
!float ## s ##_is_any_nan(b)) { \
return b; \
} else if (float ## s ## _is_quiet_nan(b, status) && \
!float ## s ## _is_any_nan(a)) { \
return a; \
} \
} \
return propagateFloat ## s ## NaN(a, b, status); \
} \
aSign = extractFloat ## s ## Sign(a); \
bSign = extractFloat ## s ## Sign(b); \
av = float ## s ## _val(a); \
bv = float ## s ## _val(b); \
if (ismag) { \
aav = float ## s ## _abs(av); \
abv = float ## s ## _abs(bv); \
if (aav != abv) { \
if (ismin) { \
return (aav < abv) ? a : b; \
} else { \
return (aav < abv) ? b : a; \
} \
} \
} \
if (aSign != bSign) { \
if (ismin) { \
return aSign ? a : b; \
} else { \
return aSign ? b : a; \
} \
} else { \
if (ismin) { \
return (aSign ^ (av < bv)) ? a : b; \
} else { \
return (aSign ^ (av < bv)) ? b : a; \
} \
} \
} \
\
float ## s float ## s ## _min(float ## s a, float ## s b, \
float_status *status) \
{ \
return float ## s ## _minmax(a, b, 1, 0, 0, status); \
} \
\
float ## s float ## s ## _max(float ## s a, float ## s b, \
float_status *status) \
{ \
return float ## s ## _minmax(a, b, 0, 0, 0, status); \
} \
\
float ## s float ## s ## _minnum(float ## s a, float ## s b, \
float_status *status) \
{ \
return float ## s ## _minmax(a, b, 1, 1, 0, status); \
} \
\
float ## s float ## s ## _maxnum(float ## s a, float ## s b, \
float_status *status) \
{ \
return float ## s ## _minmax(a, b, 0, 1, 0, status); \
} \
\
float ## s float ## s ## _minnummag(float ## s a, float ## s b, \
float_status *status) \
{ \
return float ## s ## _minmax(a, b, 1, 1, 1, status); \
} \
\
float ## s float ## s ## _maxnummag(float ## s a, float ## s b, \
float_status *status) \
{ \
return float ## s ## _minmax(a, b, 0, 1, 1, status); \
}
MINMAX(32)
MINMAX(64)
floatx80 floatx80_scalbn(floatx80 a, int n, float_status *status) floatx80 floatx80_scalbn(floatx80 a, int n, float_status *status)
{ {
flag aSign; flag aSign;

6
include/fpu/softfloat.h
View File

@@ -245,6 +245,12 @@ float16 float16_mul(float16, float16, float_status *status);
float16 float16_muladd(float16, float16, float16, int, float_status *status); float16 float16_muladd(float16, float16, float16, int, float_status *status);
float16 float16_div(float16, float16, float_status *status); float16 float16_div(float16, float16, float_status *status);
float16 float16_scalbn(float16, int, float_status *status); float16 float16_scalbn(float16, int, float_status *status);
float16 float16_min(float16, float16, float_status *status);
float16 float16_max(float16, float16, float_status *status);
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);
int float16_is_quiet_nan(float16, float_status *status); int float16_is_quiet_nan(float16, float_status *status);
int float16_is_signaling_nan(float16, float_status *status); int float16_is_signaling_nan(float16, float_status *status);