Which is certain to produce big errors at every instance where a subnormal result would have been generated or propagated otherwise.
Such options exist only for games or for experts in numeric analysis, not for general-purpose programming.
GCC does with the infamous -ffast-math as well.
IIRC that has been since split out of the flag and need to be asked for separately at link time.
If you use -ffast-math when linking an executable but not a shared library, both gcc and clang will link in crtfastmath.o which has the bit of code to set the DAZ/FTZ flags.
right, but the issue was that if an application was linked with a library that happened to link with a fast-math shared library, it would unknowingly bring along the crt code. Now the only way to get it is to use the fast-math flag when linking the final binary, which at least is an explicit request.