On 7/6/24 6:12 PM, Oleg Endo wrote:
This is almost certainly a poorly written pattern. I just fixed a bunch
of these, but not this one. Essentially a recent change in the generic
parts of the compiler is exposing some bugs in the SH backend.
The patterns were written and tested to the best of our knowledge at that
time many years ago. Nobody thought that we'll get a 2nd combine pass after
RA. Anyway, I'll have a look at the remaining patterns.
My comment wasn't meant to disparage you or anyone. Just to note that
the patterns need fixing as they are incorrect.
We have certainly had cases where the model used by those patterns would
cause problems in the past. Hard register cprop, compare elimination
and others could trigger the same kind of problem. late-combine is just
more likely to expose these kinds of latent bugs.
Jeff
