[PATCH] split, i386: Fix up df uses in i386 splitters [PR99104]

[Jakub Jelinek]

On Tue, Feb 16, 2021 at 09:55:40AM +0000, Richard Sandiford wrote:
> I assume that's because pass_df_initialize_no_opt is slightly after
> the first pass_split_all_insns?  Seems like it should just be a case
> of moving it up.
> 
> > And for noflow where the cfg doesn't really exit I wouldn't even attempt to
> > do df_analyze.
> 
> What stops ix86_ok_to_clobber_flags being called in that case?

split5 is never enabled on i386.
  virtual bool gate (function *)
    {
      /* The placement of the splitting that we do for shorten_branches
         depends on whether regstack is used by the target or not.  */
#if HAVE_ATTR_length && !defined (STACK_REGS)
      return true;
#else
      return false;
#endif
    }

	Jakub