[Bug middle-end/74113] New: by_pieces_ninsns doesn't support TImode/OImode/XImode

[hjl.tools at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=74113

            Bug ID: 74113
           Summary: by_pieces_ninsns doesn't support TImode/OImode/XImode
           Product: gcc
           Version: 7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
          Assignee: unassigned at gcc dot gnu.org
          Reporter: hjl.tools at gmail dot com
                CC: bernds at gcc dot gnu.org, rdsandiford at googlemail dot com
  Target Milestone: ---

TImode/OImode/XImode support load and store with vector registers.  But
by_pieces_ninsns determines the widest mode with MAX_FIXED_MODE_SIZE
which is limited by integer registers.  There is a patch to update
alignment_for_piecewise_move to remove the MAX_FIXED_MODE_SIZE restriction:

https://gcc.gnu.org/ml/gcc-patches/2016-04/msg01506.html

But there is a concern for simplify_immed_subreg:

https://gcc.gnu.org/ml/gcc-patches/2016-04/msg01527.html