[Bug gcov-profile/79259] New: [7 Regression] Corrupted profile when one uses -O1

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79259

            Bug ID: 79259
           Summary: [7 Regression] Corrupted profile when one uses -O1
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: gcov-profile
          Assignee: unassigned at gcc dot gnu.org
          Reporter: marxin at gcc dot gnu.org
  Target Milestone: ---

Following test-case can't properly use PGO:

gcc auto-profile.ii -fprofile-generate -O1 && ./a.out  && gcc auto-profile.ii
-fprofile-use  -O1

auto-profile.ii:17:1: error: the control flow of function ‘_Z3fn2v’ does not
match its profile data (counter ‘arcs’) [-Werror=coverage-mismatch]
 }
 ^
auto-profile.ii:17:1: error: the control flow of function ‘_Z3fn2v’ does not
match its profile data (counter ‘time_profiler’) [-Werror=coverage-mismatch]
cc1plus: some warnings being treated as errors

Started with r239769. Problem is that flag_ipa_bit_cp is enabled with
-fprofile-use. That triggers ccp1 to find nonzero bits as it's guarded with:

  if (ccp_finalize (nonzero_p || flag_ipa_bit_cp))
    {
      todo = (TODO_cleanup_cfg | TODO_update_ssa);

      /* ccp_finalize does not preserve loop-closed ssa.  */
      loops_state_clear (LOOP_CLOSED_SSA);
    }

I've got patch for that.