RFC: using clz for comparing to zero on the tree level.

[Richard Henderson]

On Thu, May 08, 2003 at 12:36:35PM -0400, David Edelsohn wrote:
> 	Not Alpha and not ARM V5, which have single instruction clz?

PPC:
	cntlz	tmp, in
	srwi	out, tmp, 5

Alpha:
	cmpeq	in, 0, out

ARM:
	cmp	in, #0
	movne	out, #0
	moveq	out, #1

Hmm, so it might be a win for ARM.  You'll have to work out
with Richard Earnshaw how you want to arrange these costs.
At the moment arm_rtx_costs doesn't tell you that the SEQ
operation takes 3 instructions.


r~