Hm. Do you do something with dmd `real_t` implementation? Compile perform float evaluation with bigger precission than runtime code, because it cast all float values to `real_t`.
What test are failed? All denormalized, or may be only real? Or only double and float but not real?
Anyway this sounds strange, because this code shouldn't depends on OS or CPU bitness. Do you use x86 or x86_64 arch?