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Fix nextafter/nexttoward overflow in directed rounding modes - #362
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nextafter/nexttoward returned
x+xwhen overflowing largest finite inputs, potentially returning finite endpoints under directed rounding instead of adjacent signed infinity.We raise overflow/inexact with
x+xin the existing volatile temporary, returning the bit-step value. Five implementation changes cover the nexttowardl alias.Regression checks both signs, all four rounding modes and overflow/inexact flags, failing before/passing after. Base/patch reproducer failures: 24/48 to 0/48 across all four library/caller combinations. Both default builds pass
make testbefore/after. Other architectures, operating systems and long-double formats weren't tested.Version: base
5fe399749f9276eaa0b8403e507470da05cbbb3f, GCC 13.3/Clang 18.1, Linux x86-64, binary80 long double.Fixes #361
— ChipLab