On 01/15/2016 06:06 AM, Bernd Schmidt wrote: > On 01/15/2016 07:05 AM, Jeff Law wrote: > >> Well, you have to write the pattern and a splitter. But these days >> there's define_insn_and_split to help with that. Reusing Bernd's work >> may ultimately be easier though. > > Maybe, but maybe also not in the way you think. I've always wanted the ability > to combine 2->2 insns, for cases like this. The parallel would be split into > two separate insns if it doesn't match. This would allow more complicated > forms > to be used if they are equally cheap, and can lead to elimination of > instructions if it triggers more combinations.
Maybe it's the same thing in the end, but I was thinking more in terms of 2->1 or 3->1, but without deleting some of the input instructions if their outputs are still used. r~
