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Issue #24999: In longobject.c, use two shifts instead of ">> 2*PyLong_SHIFT" to 

avoid undefined behaviour when LONG_MAX type is smaller than 60 bits.

This change should fix a warning with the ICC compiler.
This commit is contained in:
Victor Stinner 2015-09-19 13:39:03 +02:00
parent f2d7ea1af1
commit 5783fd2c58
1 changed files with 6 additions and 4 deletions
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10
Objects/longobject.c
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@ -4495,11 +4495,13 @@ _PyLong_GCD(PyObject *aarg, PyObject *barg)
simple: simple:
assert(Py_REFCNT(a) > 0); assert(Py_REFCNT(a) > 0);
assert(Py_REFCNT(b) > 0); assert(Py_REFCNT(b) > 0);
#if LONG_MAX >> 2*PyLong_SHIFT /* Issue #24999: use two shifts instead of ">> 2*PyLong_SHIFT" to avoid
undefined behaviour when LONG_MAX type is smaller than 60 bits */
#if LONG_MAX >> PyLong_SHIFT >> PyLong_SHIFT
/* a fits into a long, so b must too */ /* a fits into a long, so b must too */
x = PyLong_AsLong((PyObject *)a); x = PyLong_AsLong((PyObject *)a);
y = PyLong_AsLong((PyObject *)b); y = PyLong_AsLong((PyObject *)b);
#elif defined(PY_LONG_LONG) && PY_LLONG_MAX >> 2*PyLong_SHIFT #elif defined(PY_LONG_LONG) && PY_LLONG_MAX >> PyLong_SHIFT >> PyLong_SHIFT
x = PyLong_AsLongLong((PyObject *)a); x = PyLong_AsLongLong((PyObject *)a);
y = PyLong_AsLongLong((PyObject *)b); y = PyLong_AsLongLong((PyObject *)b);
#else #else
@ -4516,9 +4518,9 @@ simple:
y = x % y; y = x % y;
x = t; x = t;
} }
#if LONG_MAX >> 2*PyLong_SHIFT #if LONG_MAX >> PyLong_SHIFT >> PyLong_SHIFT
return PyLong_FromLong(x); return PyLong_FromLong(x);
#elif defined(PY_LONG_LONG) && PY_LLONG_MAX >> 2*PyLong_SHIFT #elif defined(PY_LONG_LONG) && PY_LLONG_MAX >> PyLong_SHIFT >> PyLong_SHIFT
return PyLong_FromLongLong(x); return PyLong_FromLongLong(x);
#else #else
# error "_PyLong_GCD" # error "_PyLong_GCD"