Pipelining With Multicycle Operations

• Up to now we have assumed that the EX and MEM stages can always be finished in one clock cycle.

• This may be difficult or impossible to organise

• Examples:

    $\mbox{$\mathbf{\circ}$}$

  Integer multiply

    $\mbox{$\mathbf{\circ}$}$

  Integer divide

    $\mbox{$\mathbf{\circ}$}$

  Floating-point add, multiply

    $\mbox{$\mathbf{\circ}$}$

  FP divide, square root etc

  $\star$

  Cache misses

• How does this complicate pipeline control?

(H&P pp.187,201)