On Mon, Oct 21, 2019 at 03:46:53PM +0100, Richard Earnshaw (lists) wrote: > On 19/10/2019 14:00, Segher Boessenkool wrote: > >On Fri, Oct 18, 2019 at 08:48:40PM +0100, Richard Earnshaw wrote: > >> > >>The cost routine for Arm and Thumb2 was not recognising the idioms that > >>describe the addition with carry, this results in the instructions > >>appearing more expensive than they really are, which occasionally can lead > >>to poor choices by combine. Recognising all the possible variants is > >>a little trickier than normal because the expressions can become complex > >>enough that this is no single canonical from. > > > >There also is the insn_cost hook, which especially for RISC-like targets > >is a lot easier to define. > > Easier, but not a complete replacement for rtx_costs, so not necessarily > easier in the end...
It isn't a full replacement *yet*, still chipping away at it. If your port has an rtx_cost already, adding ai reasonable insn_cost will only improve it, not regress anything. But there are some places that still need rtx_costs, yes. Do you have anything in particular in mind? PRs welcome! Segher
