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gh-104263: Rely on Py_NAN and introduce Py_INFINITY (GH-104202)

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This PR removes `_Py_dg_stdnan` and `_Py_dg_infinity` in favour of
using the standard `NAN` and `INFINITY` macros provided by C99.
This change has the side-effect of fixing a bug on MIPS where the
hard-coded value used by `_Py_dg_stdnan` gave a signalling NaN
rather than a quiet NaN.
---------

Co-authored-by: Mark Dickinson <dickinsm@gmail.com>
This commit is contained in:
Sebastian Berg 2023-05-10 18:44:52 +02:00 • committed by GitHub
parent a7a2dbbf72
commit 7a3b03509e
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GPG key ID: 4AEE18F83AFDEB23
12 changed files with 44 additions and 198 deletions
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34
Python/dtoa.c
View file

@ -273,11 +273,6 @@ typedef union { double d; ULong L[2]; } U;
#define Big0 (Frac_mask1 | Exp_msk1*(DBL_MAX_EXP+Bias-1))
#define Big1 0xffffffff
/* Standard NaN used by _Py_dg_stdnan. */
#define NAN_WORD0 0x7ff80000
#define NAN_WORD1 0
/* Bits of the representation of positive infinity. */
#define POSINF_WORD0 0x7ff00000
@ -1399,35 +1394,6 @@ bigcomp(U *rv, const char *s0, BCinfo *bc)
return 0;
}
/* Return a 'standard' NaN value.
There are exactly two quiet NaNs that don't arise by 'quieting' signaling
NaNs (see IEEE 754-2008, section 6.2.1). If sign == 0, return the one whose
sign bit is cleared. Otherwise, return the one whose sign bit is set.
*/
double
_Py_dg_stdnan(int sign)
{
U rv;
word0(&rv) = NAN_WORD0;
word1(&rv) = NAN_WORD1;
if (sign)
word0(&rv) |= Sign_bit;
return dval(&rv);
}
/* Return positive or negative infinity, according to the given sign (0 for
* positive infinity, 1 for negative infinity). */
double
_Py_dg_infinity(int sign)
{
U rv;
word0(&rv) = POSINF_WORD0;
word1(&rv) = POSINF_WORD1;
return sign ? -dval(&rv) : dval(&rv);
}
double
_Py_dg_strtod(const char *s00, char **se)

41
Python/pystrtod.c
View file

@ -23,44 +23,6 @@ case_insensitive_match(const char *s, const char *t)
return the NaN or Infinity as a double and set *endptr to point just beyond
the successfully parsed portion of the string. On failure, return -1.0 and
set *endptr to point to the start of the string. */
#if _PY_SHORT_FLOAT_REPR == 1
double
_Py_parse_inf_or_nan(const char *p, char **endptr)
{
double retval;
const char *s;
int negate = 0;
s = p;
if (*s == '-') {
negate = 1;
s++;
}
else if (*s == '+') {
s++;
}
if (case_insensitive_match(s, "inf")) {
s += 3;
if (case_insensitive_match(s, "inity"))
s += 5;
retval = _Py_dg_infinity(negate);
}
else if (case_insensitive_match(s, "nan")) {
s += 3;
retval = _Py_dg_stdnan(negate);
}
else {
s = p;
retval = -1.0;
}
*endptr = (char *)s;
return retval;
}
#else
double
_Py_parse_inf_or_nan(const char *p, char **endptr)
{
@ -84,7 +46,7 @@ _Py_parse_inf_or_nan(const char *p, char **endptr)
}
else if (case_insensitive_match(s, "nan")) {
s += 3;
retval = negate ? -Py_NAN : Py_NAN;
retval = negate ? -fabs(Py_NAN) : fabs(Py_NAN);
}
else {
s = p;
@ -94,7 +56,6 @@ _Py_parse_inf_or_nan(const char *p, char **endptr)
return retval;
}
#endif
/**
* _PyOS_ascii_strtod: