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.
Segher
Easier, but not a complete replacement for rtx_costs, so not necessarily
easier in the end...
R.
