MAINT: improved overflow check to avoid undefined behavior #21658
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I am not sure that this is bad, but feel that it can't hurt (except that it may create a merge conflict for @ganesh-k13's PR ;)). Thanks for this "detour", @Micky774! |
ganesh-k13
reviewed
Jun 9, 2022
| @@ -164,7 +166,7 @@ static NPY_INLINE int | |||
| return NPY_FPE_DIVIDEBYZERO; | |||
| } | |||
| #if @neg@ | |||
| else if (b == -1 && a < 0 && a == -a) { | |||
| else if (b == -1 && a == NPY_MIN_@NAME@) { | |||
| *out = a / b; | |||
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@seberg this leads to arithmetic exception yeah?
Thread 1 "python3.10" received signal SIGFPE, Arithmetic exception.
0x00007ffff6f9d7e0 in int_ctype_divide (out=<synthetic pointer>, b=-1, a=-2147483648) at numpy/core/src/umath/scalarmath.c.src:179
179 *out = a / b;Why do we allow a / b when its a guarantee overflow. ref: #21507
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My bad, I guess... you are right, this is nonsense, we took a bad turn somewhere here :/. Are you including the fix in your PR?
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Thanks for confirming. Yep: https://github.com/numpy/numpy/pull/21507/files#r893596218
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Related Issues/PRs
Related to #21648
Changes
NAMEtemplate to@name@_ctype_dividea == -atoa == NPY_MIN_@NAME@Comments
The old behavior was pointed out to be undefined, see: #21648 (comment))