Optimize builtin mul and div a bit
Optimize builtin mul and div a bit

ND-CSE-30151/elvm,ND-CSE-30151/elvm,shinh/elvm,shinh/elvm,shinh/elvm,ND-CSE-30151/elvm,shinh/elvm,shinh/elvm,shinh/elvm,shinh/elvm,shinh/elvm