[Bug middle-end/88302] New: __gcov_indirect_call_profiler_v2 and first_run profiling can be cheaper with LTO

["hubicka at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88302

            Bug ID: 88302
           Summary: __gcov_indirect_call_profiler_v2 and first_run
                    profiling can be cheaper with LTO
           Product: gcc
           Version: 9.0
            Status: UNCONFIRMED
          Severity: enhancement
          Priority: P3
         Component: middle-end
          Assignee: unassigned at gcc dot gnu.org
          Reporter: hubicka at gcc dot gnu.org
  Target Milestone: ---

Currently __gcov_indirect_call_profiler_v2 consumes about 3% of execution of
lto1 with -fprofile-generate during profiledbootstrap.  I do not think it is
because we have that many indirect calls at the hot path, but because we add
the prologue to every externally visible function at compile time.  It would be
nice to eliminate those that do not have address taken in whole program ;)