8324241: Always record evol_method deps to avoid excessive method flushing

Reviewed-by: eastigeevich, phh, coleenp, dlong, shade

Author: simonis

src/hotspot/share/prims/jvmtiExport.hpp

@@ -149,7 +149,15 @@ class JvmtiExport : public AllStatic {
     JVMTI_ONLY(_can_access_local_variables = (on != 0);)
   }
   inline static void set_can_hotswap_or_post_breakpoint(bool on) {
-    JVMTI_ONLY(_can_hotswap_or_post_breakpoint = (on != 0);)
+#if INCLUDE_JVMTI
+    // Check that _can_hotswap_or_post_breakpoint is not reset once it
+    // was set to true. When _can_hotswap_or_post_breakpoint is set to true
+    // _all_dependencies_are_recorded is also set to true and never
+    // reset so we have to ensure that evol dependencies are always
+    // recorded from that point on.
+    assert(!_can_hotswap_or_post_breakpoint || on, "sanity check");
+    _can_hotswap_or_post_breakpoint = (on != 0);
+#endif
   }
   inline static void set_can_walk_any_space(bool on) {
     JVMTI_ONLY(_can_walk_any_space = (on != 0);)

src/hotspot/share/prims/jvmtiRedefineClasses.cpp

@@ -4060,21 +4060,22 @@ void VM_RedefineClasses::transfer_old_native_function_registrations(InstanceKlas
 // Deoptimize all compiled code that depends on the classes redefined.
 //
 // If the can_redefine_classes capability is obtained in the onload
-// phase then the compiler has recorded all dependencies from startup.
-// In that case we need only deoptimize and throw away all compiled code
-// that depends on the class.
+// phase or 'AlwaysRecordEvolDependencies' is true, then the compiler has
+// recorded all dependencies from startup. In that case we need only
+// deoptimize and throw away all compiled code that depends on the class.
 //
-// If can_redefine_classes is obtained sometime after the onload
-// phase then the dependency information may be incomplete. In that case
-// the first call to RedefineClasses causes all compiled code to be
-// thrown away. As can_redefine_classes has been obtained then
-// all future compilations will record dependencies so second and
-// subsequent calls to RedefineClasses need only throw away code
-// that depends on the class.
+// If can_redefine_classes is obtained sometime after the onload phase
+// (and 'AlwaysRecordEvolDependencies' is false) then the dependency
+// information may be incomplete. In that case the first call to
+// RedefineClasses causes all compiled code to be thrown away. As
+// can_redefine_classes has been obtained then all future compilations will
+// record dependencies so second and subsequent calls to RedefineClasses
+// need only throw away code that depends on the class.
 //
 
 void VM_RedefineClasses::flush_dependent_code() {
   assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
+  assert(JvmtiExport::all_dependencies_are_recorded() || !AlwaysRecordEvolDependencies, "sanity check");
 
   DeoptimizationScope deopt_scope;
 

src/hotspot/share/runtime/globals.hpp

@@ -2009,6 +2009,11 @@ const int ObjectAlignmentInBytes = 8;
                                                                             \
   product(bool, ProfileExceptionHandlers, true,                             \
           "Profile exception handlers")                                     \
+                                                                            \
+  product(bool, AlwaysRecordEvolDependencies, true, EXPERIMENTAL,           \
+                "Unconditionally record nmethod dependencies on class "     \
+                "rewriting/transformation independently of the JVMTI "      \
+                "can_{retransform/redefine}_classes capabilities.")         \
 
 // end of RUNTIME_FLAGS
 

src/hotspot/share/runtime/init.cpp

@@ -115,6 +115,12 @@ void vm_init_globals() {
 jint init_globals() {
   management_init();
   JvmtiExport::initialize_oop_storage();
+#if INCLUDE_JVMTI
+  if (AlwaysRecordEvolDependencies) {
+    JvmtiExport::set_can_hotswap_or_post_breakpoint(true);
+    JvmtiExport::set_all_dependencies_are_recorded(true);
+  }
+#endif
   bytecodes_init();
   classLoader_init1();
   compilationPolicy_init();