[RTL-ifcvt] PR rtl-optimization/68841: Make sure one basic block doesn't clobber CC reg usage of the other

        PR rtl-optimization/68841
        * ifcvt.c (struct noce_if_info): Add orig_x field.
        (bbs_ok_for_cmove_arith): Add to_rename parameter.
        Don't record conflicts on to_rename if it's present.
        Allow memory destinations in sets.
        (noce_try_cmove_arith): Call bbs_ok_for_cmove_arith even on simple
        blocks, passing orig_x to the checks.
        (noce_process_if_block): Set if_info->orig_x appropriately.

        * gcc.dg/pr68841.c: New test.
        * gcc.c-torture/execute/pr68841.c: New test.

From-SVN: r232223