jdk-sandbox: comparison src/hotspot/share/code/nmethod.cpp

equal deleted inserted replaced

-:9cb53c505acd
+:4f45c682eab0
 // Tell if a non-entrant method can be converted to a zombie (i.e.,
 // there are no activations on the stack, not in use by the VM,
 // and not in use by the ServiceThread)
 bool nmethod::can_convert_to_zombie() {
-assert(is_not_entrant(), "must be a non-entrant method");
+// Note that this is called when the sweeper has observed the nmethod to be
+// not_entrant. However, with concurrent code cache unloading, the state
+// might have moved on to unloaded if it is_unloading(), due to racing
+// concurrent GC threads.
+assert(is_not_entrant() || is_unloading(), "must be a non-entrant method");
 // Since the nmethod sweeper only does partial sweep the sweeper's traversal
 // count can be greater than the stack traversal count before it hits the
 // nmethod for the second time.
-return stack_traversal_mark()+1 < NMethodSweeper::traversal_count() &&
+// If an is_unloading() nmethod is still not_entrant, then it is not safe to
-!is_locked_by_vm();
+// convert it to zombie due to GC unloading interactions. However, if it
+// has become unloaded, then it is okay to convert such nmethods to zombie.
+return stack_traversal_mark() + 1 < NMethodSweeper::traversal_count() &&
+!is_locked_by_vm() && (!is_unloading() || is_unloaded());
 }
 void nmethod::inc_decompile_count() {
 if (!is_compiled_by_c2() && !is_compiled_by_jvmci()) return;
 // Could be gated by ProfileTraps, but do not bother...
 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
 // Unregister must be done before the state change
 Universe::heap()->unregister_nmethod(this);
-_state = unloaded;
 // Log the unloading.
 log_state_change();
 #if INCLUDE_JVMCI
 // The method can only be unloaded after the pointer to the installed code
 // The Method* is gone at this point
 assert(_method == NULL, "Tautology");
 set_osr_link(NULL);
 NMethodSweeper::report_state_change(this);
+// The release is only needed for compile-time ordering, as accesses
+// into the nmethod after the store are not safe due to the sweeper
+// being allowed to free it when the store is observed, during
+// concurrent nmethod unloading. Therefore, there is no need for
+// acquire on the loader side.
+OrderAccess::release_store(&_state, (signed char)unloaded);
 }
 void nmethod::invalidate_osr_method() {
 assert(_entry_bci != InvocationEntryBci, "wrong kind of nmethod");
 // Remove from list of active nmethods
 DepTable* table = new DepTable();
 // Iterate over live nmethods and check dependencies of all nmethods that are not
 // marked for deoptimization. A particular dependency is only checked once.
-NMethodIterator iter;
+NMethodIterator iter(NMethodIterator::only_alive_and_not_unloading);
 while(iter.next()) {
 nmethod* nm = iter.method();
 // Only notify for live nmethods
-if (nm->is_alive() && !nm->is_marked_for_deoptimization()) {
+if (!nm->is_marked_for_deoptimization()) {
 for (Dependencies::DepStream deps(nm); deps.next(); ) {
 // Construct abstraction of a dependency.
 DependencySignature* current_sig = new DependencySignature(deps);
 // Determine if dependency is already checked. table->put(...) returns
 oop installed_code = JNIHandles::resolve(_jvmci_installed_code);
 if (installed_code != NULL) {
 // Update the values in the InstalledCode instance if it still refers to this nmethod
 nmethod* nm = (nmethod*)InstalledCode::address(installed_code);
 if (nm == this) {
-if (!is_alive()) {
+if (!is_alive() || is_unloading()) {
 // Break the link between nmethod and InstalledCode such that the nmethod
 // can subsequently be flushed safely.  The link must be maintained while
 // the method could have live activations since invalidateInstalledCode
 // might want to invalidate all existing activations.
 InstalledCode::set_address(installed_code, 0);
 // be invalidated.
 InstalledCode::set_entryPoint(installed_code, 0);
 }
 }
 }
-if (!is_alive()) {
+if (!is_alive() || is_unloading()) {
 // Clear these out after the nmethod has been unregistered and any
 // updates to the InstalledCode instance have been performed.
 clear_jvmci_installed_code();
 clear_speculation_log();
 }
 nmethodLocker nml(nm);
 #ifdef ASSERT
 {
 MutexLockerEx pl(Patching_lock, Mutex::_no_safepoint_check_flag);
 // This relationship can only be checked safely under a lock
-assert(!nm->is_alive() || nm->jvmci_installed_code() == installedCode(), "sanity check");
+assert(!nm->is_alive() || nm->is_unloading() || nm->jvmci_installed_code() == installedCode(), "sanity check");
 }
 #endif
 if (nm->is_alive()) {
 // Invalidating the InstalledCode means we want the nmethod

changeset 52661	4f45c682eab0
parent 52659	8b26bd8b1832
child 52781	436097b038a1