> Every time we've tried to outsmart the compiler or library writers, it's been the wrong choice (like our old MMX code). definitely we need to protect against the case that rryan mentions, but since we're not under -WERROR I prefer to just have the warning for now.

Using a double version of fabs() is a performance issue on 32 bit targets, because this is used in a loop 3 times per sample. Since the macro does not hurt, I like to keep it.