Only clear monomorphic ICs on GC after Context exit

Review URL: https://chromiumcodereview.appspot.com/9255014

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@10431 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/api.cc

@@ -741,6 +741,7 @@ void Context::Exit() {
   i::Context* last_context =
       isolate->handle_scope_implementer()->RestoreContext();
   isolate->set_context(last_context);
+  isolate->set_context_exit_happened(true);
 }
 
 

src/heap.cc

-// Copyright 2011 the V8 project authors. All rights reserved.
+// 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:
@@ -872,6 +872,8 @@ void Heap::MarkCompact(GCTracer* tracer) {
   isolate_->counters()->objs_since_last_full()->Set(0);
 
   contexts_disposed_ = 0;
+
+  isolate_->set_context_exit_happened(false);
 }
 
 

src/heap.h

-// Copyright 2011 the V8 project authors. All rights reserved.
+// 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:

src/isolate.cc

-// Copyright 2011 the V8 project authors. All rights reserved.
+// 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:
@@ -1454,7 +1454,8 @@ Isolate::Isolate()
       has_installed_extensions_(false),
       string_tracker_(NULL),
       regexp_stack_(NULL),
-      embedder_data_(NULL) {
+      embedder_data_(NULL),
+      context_exit_happened_(false) {
   TRACE_ISOLATE(constructor);
 
   memset(isolate_addresses_, 0,

src/isolate.h

@@ -1023,6 +1023,13 @@ class Isolate {
     thread_local_top_.top_lookup_result_ = top;
   }
 
+  bool context_exit_happened() {
+    return context_exit_happened_;
+  }
+  void set_context_exit_happened(bool context_exit_happened) {
+    context_exit_happened_ = context_exit_happened;
+  }
+
  private:
   Isolate();
 
@@ -1188,6 +1195,10 @@ class Isolate {
   unibrow::Mapping<unibrow::Ecma262Canonicalize> interp_canonicalize_mapping_;
   void* embedder_data_;
 
+  // The garbage collector should be a little more aggressive when it knows
+  // that a context was recently exited.
+  bool context_exit_happened_;
+
 #if defined(V8_TARGET_ARCH_ARM) && !defined(__arm__) || \
     defined(V8_TARGET_ARCH_MIPS) && !defined(__mips__)
   bool simulator_initialized_;

src/mark-compact.cc

-// Copyright 2011 the V8 project authors. All rights reserved.
+// 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:
@@ -63,6 +63,7 @@ MarkCompactCollector::MarkCompactCollector() :  // NOLINT
       compacting_(false),
       was_marked_incrementally_(false),
       collect_maps_(FLAG_collect_maps),
+      flush_monomorphic_ics_(false),
       tracer_(NULL),
       migration_slots_buffer_(NULL),
       heap_(NULL),
@@ -515,6 +516,12 @@ void MarkCompactCollector::Prepare(GCTracer* tracer) {
   // order which is not implemented for incremental marking.
   collect_maps_ = FLAG_collect_maps && !was_marked_incrementally_;
 
+  // Monomorphic ICs are preserved when possible, but need to be flushed
+  // when they might be keeping a Context alive, or when the heap is about
+  // to be serialized.
+  flush_monomorphic_ics_ =
+      heap()->isolate()->context_exit_happened() || Serializer::enabled();
+
   // Rather than passing the tracer around we stash it in a static member
   // variable.
   tracer_ = tracer;
@@ -881,7 +888,9 @@ class StaticMarkingVisitor : public StaticVisitorBase {
   static inline void VisitCodeTarget(Heap* heap, RelocInfo* rinfo) {
     ASSERT(RelocInfo::IsCodeTarget(rinfo->rmode()));
     Code* target = Code::GetCodeFromTargetAddress(rinfo->target_address());
-    if (FLAG_cleanup_code_caches_at_gc && target->is_inline_cache_stub()) {
+    if (FLAG_cleanup_code_caches_at_gc && target->is_inline_cache_stub()
+        && (target->ic_state() == MEGAMORPHIC ||
+            heap->mark_compact_collector()->flush_monomorphic_ics_)) {
       IC::Clear(rinfo->pc());
       target = Code::GetCodeFromTargetAddress(rinfo->target_address());
     } else {

src/mark-compact.h

-// Copyright 2011 the V8 project authors. All rights reserved.
+// 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:
@@ -580,6 +580,8 @@ class MarkCompactCollector {
 
   bool collect_maps_;
 
+  bool flush_monomorphic_ics_;
+
   // A pointer to the current stack-allocated GC tracer object during a full
   // collection (NULL before and after).
   GCTracer* tracer_;