On Tue, Aug 02, 2016 at 09:21:34AM -0600, Jeff Law wrote: > >>However I think there are more paradoxical subregs generated all over, > >>but the aarch64 insv code pattern did trigger more hidden bugs than > >>any other port. It is certainly unfortunate that the major source > >>of paradoxical subreg is in a target-dependent code path :( > > > >It is certainly unfortunate that paradoxical subregs exist at all! :-) > Yea. It probably seemed like a good idea 25-30 years ago, but I always > cringe when I see them being used. Yea it gives the compiler some more > freedom, but more often than not I think we'd be better off with real > extensions.
And then perhaps have some bits marked as "do not care", perhaps using a register note... This would help other cases as well. Segher
