src/hotspot/share/c1/c1_Instruction.cpp

rev 52693 : 8214352: C1: Unnecessary "compilation bailout: block join failed" with JVMTI
Summary: Invalidate Phi functions for conflicting types and avoid bailout.
Reviewed-by:

*** 825,838 ****
        }
  
        for_each_local_value(existing_state, index, existing_value) {
          Value new_value = new_state->local_at(index);
          if (new_value == NULL || new_value->type()->tag() != existing_value->type()->tag()) {
!           // The old code invalidated the phi function here
!           // Because dead locals are replaced with NULL, this is a very rare case now, so simply bail out
            return false; // BAILOUT in caller
          }
        }
  
  #ifdef ASSERT
        // check that all necessary phi functions are present
        for_each_stack_value(existing_state, index, existing_value) {
--- 825,845 ----
        }
  
        for_each_local_value(existing_state, index, existing_value) {
          Value new_value = new_state->local_at(index);
          if (new_value == NULL || new_value->type()->tag() != existing_value->type()->tag()) {
!           Phi* existing_phi = existing_value->as_Phi();
!           if (existing_phi == NULL) {
              return false; // BAILOUT in caller
            }
+           // Invalidate the phi function here. This case is very rare except for
+           // JVMTI capability "can_access_local_variables".
+           // In really rare cases we will bail out in LIRGenerator::move_to_phi.
+           existing_phi->make_illegal();
+           existing_state->invalidate_local(index);
+           TRACE_PHI(tty->print_cr("invalidating local %d because of type mismatch", index));
+         }
        }
  
  #ifdef ASSERT
        // check that all necessary phi functions are present
        for_each_stack_value(existing_state, index, existing_value) {