https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56888
--- Comment #41 from Rich Felker <bugdal at aerifal dot cx> --- > Josef Wolf mentioned that he ran into this on the gcc-help mailing list here: > https://gcc.gnu.org/ml/gcc-help/2019-10/msg00079.html I don't think that's an instance of this issue. It's normal/expected that __builtin_foo compiles to a call to foo in the absence of factors that lead to it being optimized to something simpler. The idiom of using __builtin_foo to get the compiler to emit an optimized implementation of foo for you, to serve as the public definition of foo, is simply not valid. That's kinda a shame because it would be nice to be able to do it for lots of math library functions, but of course in order for this to be able to work gcc would have to promise it can generate code for the operation for all targets, which is unlikely to be reasonable.
