[ARC] Add BI/BIH instruction support.

Use BI/BIH instruction to implement casesi pattern. Only ARC V2.

gcc/
xxxx-xx-xx  Claudiu Zissulescu  <claziss@synopsys.com>

        * config/arc/arc.c (arc_override_options): Remove
        TARGET_COMPACT_CASESI.
        * config/arc/arc.h (ASM_OUTPUT_ADDR_DIFF_ELT): Update.
        (CASE_VECTOR_MODE): Likewise.
        (CASE_VECTOR_PC_RELATIVE): Likewise.
        (CASE_VECTOR_SHORTEN_MODE): Likewise.
        (CASE_VECTOR_SHORTEN_MODE1): Delete.
        (ADDR_VEC_ALIGN): Update.
        (ASM_OUTPUT_CASE_LABEL): Undefine.
        (ASM_OUTPUT_BEFORE_CASE_LABEL): Undefine.
        (TARGET_BI_BIH): Define.
        (DEFAULT_BRANCH_INDEX): Likewise.
        * config/arc/arc.md (casesi): Rework to accept BI/BIH
        instructions, remove compact_casesi use case.
        (casesi_compact_jump): Remove.
        (casesi_dispatch): New pattern.
        * config/arc/arc.opt: Add mbranch-index option. Deprecate
        compact_casesi option.
        * doc/invoke.texi: Document mbranch-index option.

gcc/testsuite
xxxx-xx-xx  Claudiu Zissulescu  <claziss@synopsys.com>

        * gcc.target/arc/jumptable.c: New test.

From-SVN: r265675