Deopt maybe tenure allocation sites when semi-space is maximum size.

BUG=
R=mvstanton@chromium.org

Review URL: https://codereview.chromium.org/307363002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@21635 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/heap.cc

@@ -497,10 +497,10 @@ void Heap::ProcessPretenuringFeedback() {
     // we grew to the maximum semi-space size to deopt maybe tenured
     // allocation sites. We could hold the maybe tenured allocation sites
     // in a seperate data structure if this is a performance problem.
+    bool deopt_maybe_tenured = DeoptMaybeTenuredAllocationSites();
     bool use_scratchpad =
-        allocation_sites_scratchpad_length_ < kAllocationSiteScratchpadSize &&
-        new_space_.IsAtMaximumCapacity() &&
-        maximum_size_scavenges_ == 0;
+         allocation_sites_scratchpad_length_ < kAllocationSiteScratchpadSize &&
+         !deopt_maybe_tenured;
 
     int i = 0;
     Object* list_element = allocation_sites_list();
@@ -526,6 +526,11 @@ void Heap::ProcessPretenuringFeedback() {
         allocation_sites++;
       }
 
+      if (deopt_maybe_tenured && site->IsMaybeTenure()) {
+        site->set_deopt_dependent_code(true);
+        trigger_deoptimization = true;
+      }
+
       if (use_scratchpad) {
         i++;
       } else {

src/heap.h

@@ -1363,6 +1363,10 @@ class Heap {
     return maximum_size_scavenges_ > 0;
   }
 
+  bool DeoptMaybeTenuredAllocationSites() {
+    return new_space_.IsAtMaximumCapacity() && maximum_size_scavenges_ == 0;
+  }
+
   // ObjectStats are kept in two arrays, counts and sizes. Related stats are
   // stored in a contiguous linear buffer. Stats groups are stored one after
   // another.

src/objects.h

@@ -8503,6 +8503,10 @@ class AllocationSite: public Struct {
     return pretenure_decision() == kZombie;
   }
 
+  bool IsMaybeTenure() {
+    return pretenure_decision() == kMaybeTenure;
+  }
+
   inline void MarkZombie();
 
   inline bool MakePretenureDecision(PretenureDecision current_decision,