HelenOS sources

isless            110 uspace/lib/c/include/math.h #define isless(x, y)         __builtin_isless(x, y)
isless            132 uspace/lib/c/include/math.h #define isless(x, y)         (!!(__fcompare(sizeof(x), sizeof(y), (x), (y)) & __FCOMPARE_LESS))
isless            110 uspace/lib/posix/include/libc/math.h #define isless(x, y)         __builtin_isless(x, y)
isless            132 uspace/lib/posix/include/libc/math.h #define isless(x, y)         (!!(__fcompare(sizeof(x), sizeof(y), (x), (y)) & __FCOMPARE_LESS))