Le jeudi 21 octobre 2010 à 21:11 -0700, Ian Lance Taylor a écrit : > Paul Koning <paul_kon...@dell.com> writes: > > > To take that example, on the pdp11 an SImode is two HImodes. Could > > the RTL template in the MD file for, say, addsi3 split that into two > > or three insns that operate on HImode values and describe the actual > > instructions? In this case: add high parts, then add low parts and > > propagate carry into high. Split that way it would seem you would not > > be constrained to adjacent registers, or for that matter to both being > > registers at all.
This is exactly the kind of thing I'm looking at. > The lower subreg pass will do that for you if you have the right set of > insns. Could you expand a bit on what the 'right set of instructions' is or even better give an example of an md file where we could find an example? Thanks a lot! Fred
