On Mon, Jul 17, 2017 at 12:20:16PM +0200, Richard Biener wrote: > > So I argue that we want to have a hook for insn cost. > > And I think at previous GNU Cauldrons we agreed to that.
Excellent! So now it just needs to happen ;-) > > Now what should it take as input? An rtx_insn, or just the pattern > > (as insn_rtx_cost does)? > > Is there any useful info on the other operands of an rtx_insn? If not > then passing in the pattern (a rtx) might be somewhat more flexible. > Of course it's then way easier to confuse rtx_cost and insn_cost ... > > > And if an rtx_insn, should that than be an > > rtx_insn that is already linked into the insn chain (so we can see what > > other insns generate its inputs, and which of its outputs are unused, > > etc.)? I think you need an insn for the dataflow things. But, not all callers can use that I suppose (combine can -- although combine currently does not keep useful DF info). I guess we should start with just pattern_cost. Segher
