Hi Segher, Really appreciate your review comments. On 11/8/2022 上午 1:38, Segher Boessenkool wrote: > Hi! > > Sorry for the tardiness. > > On Fri, Jul 22, 2022 at 03:07:55PM +0800, HAO CHEN GUI wrote: >> This patch creates a new function - change_pseudo_and_mask. If recog fails, >> the function converts a single pseudo to the pseudo AND with a mask if the >> outer operator is IOR/XOR/PLUS and inner operator is ASHIFT or AND. The >> conversion helps pattern to match rotate and mask insn on some targets. > > The name isn't so clear. It isn't changing a mask, to start with. How about setting function name to change_pseudo? It converts a pseudo to the pseudo AND with a mask in a particular situation.
> >> +/* When the outer code of set_src is IOR/XOR/PLUS and the inner code is >> + ASHIFT/AND, > > "When the outercode of the SET_SRC of PAT is ..." Yeah, I will change it. > >> convert a pseudo to pseudo AND with a mask if its nonzero_bits >> + is less than its mode mask. The nonzero_bits in later passes is not a >> + superset of what is known in combine pass. So an insn with nonzero_bits >> + can't be recoged later. */ > > Can this not be done with a splitter in the machine description? > Sorry, I don't quite understand it. Do you mean if the conversion can be done in split pass? If a pseudo has DImode and stem from a char, we get nonzero_bits as 0xff in combine pass. But in split pass, it's nonzero_bits is 0xffffffffffffffff. So the conversion can only be done in combine pass. Thanks Gui Haochen
