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. Segher
