Fixes in issue in the qsort comparison function #1997
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…of large values, when cast to an int, could lead to undefined behavior (integer overflow/underflow), resulting in data errors.
jedwards4b
approved these changes
Jan 22, 2025
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With 64-bit offsets, when comparing very large values found in ultra-high resolution configurations, the difference of the two iomap values can be greater than the size of a 32-bit integer, leading to undefined behavior, and causing incorrect reads.
Note that this change does technically double the instruction count for this part of the function from 3 -> 6 instructions under a couple of compilers looked at, but it didn't seem to have any practical impact on the few tests run. Submitting as-is for now, and if later more thorough tests show a performance problem, we can always do an ifdef based on type.