https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97417
--- Comment #35 from Jim Wilson <wilson at gcc dot gnu.org> --- By combine issue, are you referring to the regression I mentioned in comment 3 and filed as bug 97747? We can handle that as a separate issue. It should be uncommon. I expect to get much more benefit from this patch than the downside due to that combine issue. As for the shorten-memrefs problem, I didn't notice that one in my testing. It does need to be fixed. Taking a look now, it looks pretty simple to fix. The code currently looks for MEM, it needs to handle (SIGN_EXTEND (MEM)) and ((ZERO_EXTEND (MEM)). See the get_si_mem_base_reg function. You need to skip over the sign_extend or zero_extend when looking fot the mem at the first call. Then at the second call you need to be careful to put the sign_extend or zero_extend back when creating the new RTL. Maybe just another arg to get_si_mem_base so it can record the parent rtx code of the mem. Or maybe do this outside get_si_mem_base to skip over a sign/zero extend at the first call, and then do the same at the second call but record what rtx we skipped over so that we can put it back. We can either handle this here or as another patch. But since you have some time while waiting for paperwork maybe you can try writing a fix.
