[Bug libstdc++/83607] New: std::boyer_moore_searcher is slow searching through arrays of std::byte

["m101010a at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83607

            Bug ID: 83607
           Summary: std::boyer_moore_searcher is slow searching through
                    arrays of std::byte
           Product: gcc
           Version: 7.2.1
            Status: UNCONFIRMED
          Keywords: missed-optimization
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: m101010a at gmail dot com
  Target Milestone: ---

Created attachment 42975
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=42975&action=edit
C++17 program demonstrating the issue

When using std::boyer_moore_searcher on an array of std::bytes, it is 3 times
as slow as memmem.  When using std::boyer_moore_searcher on an array of
unsigned char, it is faster them memmem.  This is because the searcher uses an
array when searching through unsigned chars, but uses a hash table when
searching through std::byte.  Searches through std::byte should also use an
array, since it has the same size and equality semantics as unsigned char.