On Thu, Nov 24, 2022 at 8:25 AM HAO CHEN GUI <guih...@linux.ibm.com> wrote: > > Hi Richard, > > > 在 2022/11/24 4:06, Richard Biener 写道: > > Wouldn't we usually either add an optab or try to recog a canonical > > RTL form instead of adding a new target hook for things like this? > > Thanks so much for your comments. Please let me make it clear. > > Do you mean we should create an optab for "setb" pattern (the nested > if-then-else insn) and detect candidate insns in ifcvt pass? Then > generate the insn with the new optab?
Yes, that would be one way to do it. Another way would be to generate a (to be defined) canonical form of such instruction and see whether it can be recognized (whether there's a define_insn for it). Note that were just things that came into my mind here, I'm not too familiar with how we handle such situations but at least I'm not aware of dozens of target hooks to handle instruction availability. Richard. > My concern is that some candidate insns are target specific. For > example, different modes cause additional zero_extend or subreg insns > generated on different targets. So I put the detection process into a > target hook. > > Looking forward to your advice. > > Thanks again > Gui Haochen
