8068915: uncommon trap w/ Reason_speculate_class_check causes performance...

8068915: uncommon trap w/ Reason_speculate_class_check causes performance regression due to continuous deoptimizations
Reviewed-by: kvn, roland, jrose

src/share/vm/opto/graphKit.cpp

@@ -1980,6 +1980,11 @@ void GraphKit::uncommon_trap(int trap_request,
         Deoptimization::trap_request_index(trap_request) < 0 &&
         too_many_recompiles(reason)) {
       // This BCI is causing too many recompilations.
+      if (C->log() != NULL) {
+        C->log()->elem("observe that='trap_action_change' reason='%s' from='%s' to='none'",
+                Deoptimization::trap_reason_name(reason),
+                Deoptimization::trap_action_name(action));
+      }
       action = Deoptimization::Action_none;
       trap_request = Deoptimization::make_trap_request(reason, action);
     } else {
@@ -2742,7 +2747,7 @@ Node* GraphKit::maybe_cast_profiled_receiver(Node* not_null_obj,
   Deoptimization::DeoptReason reason = spec_klass == NULL ? Deoptimization::Reason_class_check : Deoptimization::Reason_speculate_class_check;
 
   // Make sure we haven't already deoptimized from this tactic.
-  if (too_many_traps(reason))
+  if (too_many_traps(reason) || too_many_recompiles(reason))
     return NULL;
 
   // (No, this isn't a call, but it's enough like a virtual call
@@ -2764,8 +2769,7 @@ Node* GraphKit::maybe_cast_profiled_receiver(Node* not_null_obj,
                                             &exact_obj);
       { PreserveJVMState pjvms(this);
         set_control(slow_ctl);
-        uncommon_trap(reason,
-                      Deoptimization::Action_maybe_recompile);
+        uncommon_trap_exact(reason, Deoptimization::Action_maybe_recompile);
       }
       if (safe_for_replace) {
         replace_in_map(not_null_obj, exact_obj);
@@ -2793,8 +2797,8 @@ Node* GraphKit::maybe_cast_profiled_obj(Node* obj,
   if (type != NULL) {
     Deoptimization::DeoptReason class_reason = Deoptimization::Reason_speculate_class_check;
     Deoptimization::DeoptReason null_reason = Deoptimization::Reason_null_check;
-    if (!too_many_traps(null_reason) &&
-        !too_many_traps(class_reason)) {
+    if (!too_many_traps(null_reason) && !too_many_recompiles(null_reason) &&
+        !too_many_traps(class_reason) && !too_many_recompiles(class_reason)) {
       Node* not_null_obj = NULL;
       // not_null is true if we know the object is not null and
       // there's no need for a null check
@@ -2813,14 +2817,14 @@ Node* GraphKit::maybe_cast_profiled_obj(Node* obj,
       {
         PreserveJVMState pjvms(this);
         set_control(slow_ctl);
-        uncommon_trap(class_reason,
-                      Deoptimization::Action_maybe_recompile);
+        uncommon_trap_exact(class_reason, Deoptimization::Action_maybe_recompile);
       }
       replace_in_map(not_null_obj, exact_obj);
       obj = exact_obj;
     }
   } else {
-    if (!too_many_traps(Deoptimization::Reason_null_assert)) {
+    if (!too_many_traps(Deoptimization::Reason_null_assert) &&
+        !too_many_recompiles(Deoptimization::Reason_null_assert)) {
       Node* exact_obj = null_assert(obj);
       replace_in_map(obj, exact_obj);
       obj = exact_obj;