[Bug target/77685] rs6000 target has builtin expansion for memcpy but not memcmp

[acsawdey at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77685

--- Comment #1 from acsawdey at gcc dot gnu.org ---
fixed in 240455:

2016-09-23  Aaron Sawdey  <acsawdey@linux.vnet.ibm.com>

        * config/rs6000/rs6000.md (cmpmemsi): New define_expand.
        * config/rs6000/rs6000.c (expand_block_compare): New function used by
        cmpmemsi pattern to do builtin expansion of memcmp ().
        (compute_current_alignment): Add helper function for
        expand_block_compare used to compute alignment as the compare proceeds.
        (select_block_compare_mode): Used by expand_block_compare to select
        the mode used for reading the next chunk of bytes in the compare.
        (do_load_for_compare): Used by expand_block_compare to emit the load
        insns for the compare.
        (rs6000_emit_dot_insn): Moved this function to avoid a forward
        reference from expand_block_compare ().
        * config/rs6000/rs6000-protos.h (expand_block_compare): Add a
        prototype for this function.
        * config/rs6000/rs6000.opt (mblock-compare-inline-limit): Add a new
        target option for controlling how much code inline expansion of
        memcmp() will be allowed to generate.