gh-143006: Fix and optimize mixed comparison of float and int #143084
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When comparing negative non-integer float and int with the same number of bits in the integer part, __neg__() in the int subclass returning not an int caused an assertion error. Now the integer is no longer negated. Also, reduced the number of temporary created Python objects.
serhiy-storchaka
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needs backport to 3.13
skirpichev
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Dec 22, 2025
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This approach looks better for me. Few minor nits.
| /* Convert w to a double if it fits. In particular, 0 fits. */ | ||
| int64_t nbits64 = _PyLong_NumBits(w); | ||
| assert(nbits64 >= 0); | ||
| assert(!PyErr_Occurred()); |
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It checks that _PyLong_NumBits() does not fail. It newer fails now.
Objects/floatobject.c
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| } | ||
| /* v and w have the same number of bits before the radix | ||
| * point. Construct two ints that have the same comparison | ||
| * outcome. |
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skirpichev
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Dec 23, 2025
skirpichev
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| if (vsign < 0) { | ||
| op = Py_GT; // v >= w <=> trunc(v) > w | ||
| } |
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Perhaps, it might worth to do sign canonicalization, as before, to get rid of such cases. But I think we have to expose long_neg() for this.
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It will only remove 2 of 6 cases and simplify other 2. The code for negation of both arguments is more complex.
We could also use two tables, this would make the code smaller: op = table[vsign > 0][op].
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When comparing negative non-integer float and int with the same number of bits in the integer part,
__neg__()in the int subclass returning not an int caused an assertion error.Now the integer is no longer negated. Also, reduced the number of temporary created Python objects.
float_richcomparevia re-entrant__neg__#143006