Very Long Instruction Word

Superscalar vs VLIW

OOO Superscalar In-Order Superscalar VLIW
IPC <=N <=N 1 Large Inst some work as N “normal” insts
How do we find indep. inst. Look at >N insts Look at next N insts in program order Just do next large inst
Hardware cost Expensive Less Expensive Even Less Expensive
Help from compiler Compiler can help Needs help Completely depends on compiler

VLIW: The Good and the Bad



VLIW Instructions

VLIW Examples

Note: good for adding -> Counting -> figuring out stuff