Support full deoptimization during GC via stack guard.

src/heap.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 934 matching lines @@
       IsHighSurvivalRate()) {
     // Stable high survival rates even though young generation is at
     // maximum capacity indicates that most objects will be promoted.
     // To decrease scavenger pauses and final mark-sweep pauses, we
     // have to limit maximal capacity of the young generation.
     new_space_high_promotion_mode_active_ = true;
     if (FLAG_trace_gc) {
       PrintPID("Limited new space size due to high promotion rate: %d MB\n",
                new_space_.InitialCapacity() / MB);
     }
+    // Support for global pre-tenuring uses the high promotion mode as a
+    // heuristic indicator of whether to pretenure or not, we trigger
+    // deoptimization here to take advantage of pre-tenuring as soon as
+    // possible.
+    if (FLAG_pretenure_literals) {
+      isolate_->stack_guard()->FullDeopt();
+    }
   } else if (new_space_high_promotion_mode_active_ &&
       IsStableOrDecreasingSurvivalTrend() &&
       IsLowSurvivalRate()) {
     // Decreasing low survival rates might indicate that the above high
     // promotion mode is over and we should allow the young generation
     // to grow again.
     new_space_high_promotion_mode_active_ = false;
     if (FLAG_trace_gc) {
       PrintPID("Unlimited new space size due to low promotion rate: %d MB\n",
                new_space_.MaximumCapacity() / MB);
@@ skipping 6848 matching lines @@
       static_cast<int>(object_sizes_last_time_[index]));
   FIXED_ARRAY_SUB_INSTANCE_TYPE_LIST(ADJUST_LAST_TIME_OBJECT_COUNT)
 #undef ADJUST_LAST_TIME_OBJECT_COUNT
 
   memcpy(object_counts_last_time_, object_counts_, sizeof(object_counts_));
   memcpy(object_sizes_last_time_, object_sizes_, sizeof(object_sizes_));
   ClearObjectStats();
 }
 
 } }  // namespace v8::internal