[Bug middle-end/114084] ICE: SIGSEGV: infinite recursion in fold_build2_loc / fold_binary_loc with _BitInt(127)

["jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114084

--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Or perhaps the
          if (ok
              && ((var0 != 0) + (var1 != 0)
                  + (minus_var0 != 0) + (minus_var1 != 0)
                  + (con0 != 0) + (con1 != 0)
                  + (minus_con0 != 0) + (minus_con1 != 0)
                  + (lit0 != 0) + (lit1 != 0)
                  + (minus_lit0 != 0) + (minus_lit1 != 0)) > 2)
condition should be amended to avoid the reassociation in cases where clearly
nothing good can come out of that.  Which is if the association actually
doesn't reshuffle anything.  (var0 == 0) || (var1 == 0) && (and similarly for
the other 5 pairs) and
(ignoring the minus_* stuff that would need more thoughts on it)
(con0 != 0 && lit0 != 0) || (con1 != 0 && lit1 != 0),
then it reassociates to the original stuff in op0 and original stuff in op1,
no change.  But how the minus_* plays together with this is harder.
Perhaps if lazy we could have a bool var whether there has been any association
between subtrees from original op0 and op1, initially set to false and set if
we associate_trees between something that comes from op0 and op1, and only do
the final
associate_trees if that is the case, because if not, it should be folding of
the individual suboperands, not reassociation.