On Mon, Apr 06, 2015 at 07:56:53PM -0400, David Edelsohn wrote: > Okay. > > What's the source of COSTS_N_INSNS(3) value?
It is the basic cost of a FP insn (i.e. it duplicates what rs6000_cost->fp would be -- all of the simple FP ops are this value, XSADDDP, XSMULDP, etc. including the two move insns XSCPSGNDP and FMR). On the power7 and power8, each basic FP op is 6 cycles, and all of the costs use the fact that COSTS_N_INSNS multiplies by 2. Obviously in the grand scheme of things, we need to rewrite the cost infrastructure, and bring it up to date, but for now, I used the values for the other insns. -- Michael Meissner, IBM IBM, M/S 2506R, 550 King Street, Littleton, MA 01460-6245, USA email: meiss...@linux.vnet.ibm.com, phone: +1 (978) 899-4797
