Comment 16 for bug 1811798

(In reply to Andreas Krebbel from comment #14)
> (In reply to Jakub Jelinek from comment #11)
> > ... Can't what you are doing in the splitters be done in
> > define_peephole2 instead?
>
> Not that easy unfortunately. peephole2 will run after reload. So the FP
> constant ok 0.0 will already be reloaded into a register first or pushed
> into literal pool. The point of doing the transformation is to avoid this.

But it is still invalid. If those splitters are essentially to you and worth slowing the compiler on s390*, then you could e.g. add a custom target pass right before split1, where you'd just df_note_addr_problem (); df_analyze (); and thus ensured that during the splitting you could use the REG_DEAD/REG_UNUSED notes safely. In the splitters you'd likely need to use current_pass to verify you are in the pass for which you've done this.