s390: Constraints, predicates, and op letters for contiguous bitmasks

s390: Constraints, predicates, and op letters for contiguous bitmasks

        * config/s390/constraints.md (NxxDq, NxxSq): New.
        * config/s390/predicates.md (contiguous_bitmask_operand): New.
        * config/s390/s390.c (print_operand) ['e', 'f', 's', 't']: New
        operand letters.
        * config/s390/s390.md (bfstart, bfend): New mode attrs.
        (*insv<GPR>_zEC12_noshift): Use them.
        (*insv<GPR>_z10_noshift): Likewise.
        (*insv<GPR>_or_z10_noshift): Likewise.

Co-Authored-By: Andreas Krebbel <Andreas.Krebbel@de.ibm.com>
From-SVN: r194640