Cleanup allocation site pretenuring tracing, added new flag --trace-pretenuring-statistics.

src/objects-inl.h

Index: src/objects-inl.h
diff --git a/src/objects-inl.h b/src/objects-inl.h
index 18926bfbb1d57e9e0449ea888be13e4992b7cdb4..a0256fb416429940c41002429ae7731c6024e984 100644
--- a/src/objects-inl.h
+++ b/src/objects-inl.h
@@ -1550,14 +1550,11 @@ inline void AllocationSite::IncrementMementoCreateCount() {
 inline bool AllocationSite::DigestPretenuringFeedback() {
   bool decision_changed = false;
   int create_count = memento_create_count();
+  int found_count = memento_found_count();
+  double ratio = static_cast<double>(found_count) / create_count;
+  PretenureFlag current_mode = GetPretenureMode();

[mvstanton, 2014/02/06 10:30:42]

This is a little more expensive, because we are only computing ratio for
printing purposes if we didn't meet kPretenureMinimumCreated.

Can it be organized such that we don't compute ratio if there is no audience for
the computation?

[Hannes Payer (out of office), 2014/02/06 10:47:27]

I do not think that this is an issue, but we can do that.

+
   if (create_count >= kPretenureMinimumCreated) {
-    int found_count = memento_found_count();
-    double ratio = static_cast<double>(found_count) / create_count;
-    if (FLAG_trace_track_allocation_sites) {
-      PrintF("AllocationSite: %p (created, found, ratio) (%d, %d, %f)\n",
-             static_cast<void*>(this), create_count, found_count, ratio);
-    }
-    int current_mode = GetPretenureMode();
     PretenureDecision result = ratio >= kPretenureRatio
         ? kTenure
         : kDontTenure;
@@ -1570,6 +1567,14 @@ inline bool AllocationSite::DigestPretenuringFeedback() {
     }
   }
 
+  if (FLAG_trace_pretenuring_statistics) {
+    PrintF(
+        "AllocationSite(%p): (created, found, ratio) (%d, %d, %f) %s => %s\n",
+         static_cast<void*>(this), create_count, found_count, ratio,
+         current_mode == TENURED ? "tenured" : "not tenured",
+         GetPretenureMode() == TENURED ? "tenured" : "not tenured");
+  }
+

[mvstanton, 2014/02/06 10:30:42]

Why drive a VW when you can have a Cadillac? Can the printing tell us about the
decision making above, like: did we decide, or did we "change our mind" and mark
for deopt?

[Hannes Payer (out of office), 2014/02/06 10:47:27]

We do exactly that in old state => new state.

   // Clear feedback calculation fields until the next gc.
   set_memento_found_count(0);
   set_memento_create_count(0);