On 11/04/09 10:14, Vladimir Makarov wrote:
I am agree with Jeff. It is hard to understand what you are doing
without the architecture knowledge and some macro values in your port
(IRA_COVER_CLASSES, MEMORY_MOVE_COST, and REGISTER_MOVE_COST).
I'd also add that besides right macro value definitions, you could use
insn alternative hints near register constraints like ? or even *.
I was wondering about the constraints in particular. ISTM that for
insns where TOP_REGS and BOTTOM_REGS have differing costs that the
constraint letters for TOP_REGS ought to have a '?' to show they're
slightly more costly than BOTTOM_REGS.
Alternately IRA_HARD_REGNO_ADD_COST_MULTIPLER might be used to get
BOTTOM_REGS preferred without having to add a zillion '?' modifiers to
the constraints in the machine description.
jeff
