On Sat, 3 May 2025, Paul Koning wrote: > > As for MEM(MEM(xyz)) addressing modes I'm less sure - I suppose those > > are usually formed at RTL expansion time (rather than, say, by > > RTL combine)? If PDP-11 is the only target with those then it might > > be easier to recover those post-LRA during late-combine or peephole > > or alternatively in a target specific pass? But of course I know > > nothing about the constraints of said addressing mode or the challenges > > those present to LRA. > > VAX also has them, in fact VAX addressing modes are a superset of the > PDP11 ones.
Indeed, with the VAX target there's double-indirect postincrement too, and then an index can be optionally applied to all these modes. We get very good results with old reload for some scenarios with efficient compact code produced. Maciej
