libm -fno-builtin

[Jon Beniston]

Hi,

 

libm is currently built with -fno-builtin. This results in sub-optimal code
for uses of functions such as fabs & floor. Without -fno-builtin, gcc can
inline these to single instructions on many targets. As is, we end up with
function calls, to slower generic code.

 

Can -fno-builtin therefore be removed? If there are specific builtins that
need to be prevented from being used, these can prevented with
-fno-builtin-function, perhaps even on a per file basis rather than
globally.

 

Are there any known traps before I give it a try?

 

Cheers,

Jon