602     case relocInfo::opt_virtual_call_type:
 603       if (!clean_if_nmethod_is_unloaded(CompiledIC_at(&iter), this, clean_all)) {
 604         return false;
 605       }
 606       break;
 607 
 608     case relocInfo::static_call_type:
 609       if (!clean_if_nmethod_is_unloaded(compiledStaticCall_at(iter.reloc()), this, clean_all)) {
 610         return false;
 611       }
 612       break;
 613 
 614     default:
 615       break;
 616     }
 617   }
 618 
 619   return true;
 620 }
 621 
 622 // Iterating over all nmethods, e.g. with the help of CodeCache::nmethods_do(fun) was found
 623 // to not be inherently safe. There is a chance that fields are seen which are not properly
 624 // initialized. This happens despite the fact that nmethods_do() asserts the CodeCache_lock
 625 // to be held.
 626 // To bundle knowledge about necessary checks in one place, this function was introduced.
 627 // It is not claimed that these checks are sufficient, but they were found to be necessary.
 628 bool CompiledMethod::nmethod_access_is_safe(nmethod* nm) {
 629   Method* method = (nm == NULL) ? NULL : nm->method();  // nm->method() may be uninitialized, i.e. != NULL, but invalid
 630   return (nm != NULL) && (method != NULL) && (method->signature() != NULL) &&
 631          !nm->is_zombie() && !nm->is_not_installed() &&
 632          os::is_readable_pointer(method) &&
 633          os::is_readable_pointer(method->constants()) &&
 634          os::is_readable_pointer(method->signature());
 635 }
 636 
 637 class HasEvolDependency : public MetadataClosure {
 638   bool _has_evol_dependency;
 639  public:
 640   HasEvolDependency() : _has_evol_dependency(false) {}
 641   void do_metadata(Metadata* md) {
 642     if (md->is_method()) {
 643       Method* method = (Method*)md;
 644       if (method->is_old()) {
 645         _has_evol_dependency = true;
 646       }
 647     }
 648   }
 649   bool has_evol_dependency() const { return _has_evol_dependency; }
 650 };
 651 
 652 bool CompiledMethod::has_evol_metadata() {
 653   // Check the metadata in relocIter and CompiledIC and also deoptimize
 654   // any nmethod that has reference to old methods.
 655   HasEvolDependency check_evol;
 656   metadata_do(&check_evol);

 602     case relocInfo::opt_virtual_call_type:
 603       if (!clean_if_nmethod_is_unloaded(CompiledIC_at(&iter), this, clean_all)) {
 604         return false;
 605       }
 606       break;
 607 
 608     case relocInfo::static_call_type:
 609       if (!clean_if_nmethod_is_unloaded(compiledStaticCall_at(iter.reloc()), this, clean_all)) {
 610         return false;
 611       }
 612       break;
 613 
 614     default:
 615       break;
 616     }
 617   }
 618 
 619   return true;
 620 }
 621 















 622 class HasEvolDependency : public MetadataClosure {
 623   bool _has_evol_dependency;
 624  public:
 625   HasEvolDependency() : _has_evol_dependency(false) {}
 626   void do_metadata(Metadata* md) {
 627     if (md->is_method()) {
 628       Method* method = (Method*)md;
 629       if (method->is_old()) {
 630         _has_evol_dependency = true;
 631       }
 632     }
 633   }
 634   bool has_evol_dependency() const { return _has_evol_dependency; }
 635 };
 636 
 637 bool CompiledMethod::has_evol_metadata() {
 638   // Check the metadata in relocIter and CompiledIC and also deoptimize
 639   // any nmethod that has reference to old methods.
 640   HasEvolDependency check_evol;
 641   metadata_do(&check_evol);