mirrors/cpython
1
0
Fork 0
mirror of https://github.com/python/cpython.git synced 2025-10-04 06:06:44 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions 12

[3.6] fixes bpo-31373: fix undefined floating-point demotions (GH-3396) (#3424)

Browse source 
(cherry picked from commit a853a8ba78)
This commit is contained in:
Miss Islington (bot) 2017-09-07 11:35:03 -07:00 • committed by Benjamin Peterson
parent b0d0217c0e
commit b03623227e
5 changed files with 51 additions and 30 deletions
Download patch file Download diff file Expand all files Collapse all files

32
Include/pymath.h
View file

@ -187,14 +187,14 @@ PyAPI_FUNC(void) _Py_set_387controlword(unsigned short);
* result.
* Caution:
* This isn't reliable. C99 no longer requires libm to set errno under
* any exceptional condition, but does require +- HUGE_VAL return
* values on overflow. A 754 box *probably* maps HUGE_VAL to a
* double infinity, and we're cool if that's so, unless the input
* was an infinity and an infinity is the expected result. A C89
* system sets errno to ERANGE, so we check for that too. We're
* out of luck if a C99 754 box doesn't map HUGE_VAL to +Inf, or
* if the returned result is a NaN, or if a C89 box returns HUGE_VAL
* in non-overflow cases.
* any exceptional condition, but does require +- HUGE_VAL return
* values on overflow. A 754 box *probably* maps HUGE_VAL to a
* double infinity, and we're cool if that's so, unless the input
* was an infinity and an infinity is the expected result. A C89
* system sets errno to ERANGE, so we check for that too. We're
* out of luck if a C99 754 box doesn't map HUGE_VAL to +Inf, or
* if the returned result is a NaN, or if a C89 box returns HUGE_VAL
* in non-overflow cases.
* X is evaluated more than once.
* Some platforms have better way to spell this, so expect some #ifdef'ery.
*
@ -211,8 +211,20 @@ PyAPI_FUNC(void) _Py_set_387controlword(unsigned short);
#define Py_OVERFLOWED(X) isinf(X)
#else
#define Py_OVERFLOWED(X) ((X) != 0.0 && (errno == ERANGE || \
(X) == Py_HUGE_VAL || \
(X) == -Py_HUGE_VAL))
(X) == Py_HUGE_VAL || \
(X) == -Py_HUGE_VAL))
#endif
/* Return whether integral type *type* is signed or not. */
#define _Py_IntegralTypeSigned(type) ((type)(-1) < 0)
/* Return the maximum value of integral type *type*. */
#define _Py_IntegralTypeMax(type) ((_Py_IntegralTypeSigned(type)) ? (((((type)1 << (sizeof(type)*CHAR_BIT - 2)) - 1) << 1) + 1) : ~(type)0)
/* Return the minimum value of integral type *type*. */
#define _Py_IntegralTypeMin(type) ((_Py_IntegralTypeSigned(type)) ? -_Py_IntegralTypeMax(type) - 1 : 0)
/* Check whether *v* is in the range of integral type *type*. This is most
* useful if *v* is floating-point, since demoting a floating-point *v* to an
* integral type that cannot represent *v*'s integral part is undefined
* behavior. */
#define _Py_InIntegralTypeRange(type, v) (_Py_IntegralTypeMin(type) <= v && v <= _Py_IntegralTypeMax(type))
#endif /* Py_PYMATH_H */