[Bug tree-optimization/71258] New: Missed optimizations: dynamic allocation, virtual calls, empty destructors

[rureclonic at thraml dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71258

            Bug ID: 71258
           Summary: Missed optimizations: dynamic allocation, virtual
                    calls, empty destructors
           Product: gcc
           Version: 6.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: rureclonic at thraml dot com
  Target Milestone: ---

clang: https://godbolt.org/g/IjYT24
gcc: https://godbolt.org/g/nkGVdB

It would seem gcc is not able to eliminate the calls to new, the virtual call
to concept::magic and the destructors, while clang completely optimizes out the
program.

interesting variation: https://godbolt.org/g/2ic8qL

Interleaving the construction of polys with the additions produces an output
with no virtual calls to concept::magic, yet without eliminating the calls to
new and destructors.