core.intrinsics

[Stefan Koch via Digitalmars-d]

Hi,

while working on a faster auto-decoding it became oblivous that 
branch-prediction primitives such as the llvm_expect or 
builtin_expect are quite useful and should be avilable in a 
cross-platform compatible way.

I propose to add a new module to to druntime called 
core.intrinsics that would have  functions like
bool likely (bool expr);
bool unlikely (bool expr);
and maybe
void prefetch(void* mem)

Please share your thoughts and tell me what other intrincic 
functions could/should be added.