Oko commented on replacing Clang/LLVM in the base installation earlier, and suggesting
lang/pcc.
I'll reiterate, that it would be good if in a future release that a lightweight compiler were included that can compile the kernel and FreeBSD base. GCC should be moved out completely. Then leave LLVM/Clang out of the base installation, except for a few libraries, and a program that asks, which Clang version would you like to install a package of or compile. Clang has to be installed a second time to a newer version for some programs.
It seems that, pcc can only compile C and not C++ or other base and kernel requirements, if I'm not mistaken. TenDRA (
lang/TenDRA) however does take care of C++; it is no longer in ports, because the last website it had is no longer, but it's at
http://www.tendra.org/. Its license is unclear, but it says current development is BSD licensed. If some lightweight combination of pcc or TenDRA can compile kernel and base, that would be cool.
I removed all compilers and other programs from
src.conf to build a base, in an attempt to use a package of
devel/llvm39. It did shave 2 hours off of base compile time, but it left me with a system that could only use packages or could only compile basic C programs, but not the kernel.
Another suggestion is for base compilers' and their tools' directories to be under one directory such as
/usr/compilers/. I'm not certain, but it seems that newer versions from packages of clang rely on parts from the base installation, which has a duplicate replacement.