Make maps in monomorphic IC stubs weak.

src/mark-compact.cc

Index: src/mark-compact.cc
diff --git a/src/mark-compact.cc b/src/mark-compact.cc
index f04a8bcb9a64105a496b8e4926cc833d06b7bc3a..b2b782bd879b0c2555f4280bb7e9ca234b22290c 100644
--- a/src/mark-compact.cc
+++ b/src/mark-compact.cc
@@ -449,7 +449,7 @@ void MarkCompactCollector::CollectGarbage() {
 
 #ifdef VERIFY_HEAP
   if (heap()->weak_embedded_objects_verification_enabled()) {
-    VerifyWeakEmbeddedObjectsInOptimizedCode();
+    VerifyWeakEmbeddedObjectsInCode();
   }
   if (FLAG_collect_maps && FLAG_omit_map_checks_for_leaf_maps) {
     VerifyOmittedMapChecks();
@@ -510,13 +510,13 @@ void MarkCompactCollector::VerifyMarkbitsAreClean() {
 }
 
 
-void MarkCompactCollector::VerifyWeakEmbeddedObjectsInOptimizedCode() {
+void MarkCompactCollector::VerifyWeakEmbeddedObjectsInCode() {
   HeapObjectIterator code_iterator(heap()->code_space());
   for (HeapObject* obj = code_iterator.Next();
        obj != NULL;
        obj = code_iterator.Next()) {
     Code* code = Code::cast(obj);
-    if (code->kind() != Code::OPTIMIZED_FUNCTION) continue;
+    if (!code->is_optimized_code() && !code->is_weak_stub()) continue;
     if (WillBeDeoptimized(code)) continue;
     code->VerifyEmbeddedObjectsDependency();
   }
@@ -2720,7 +2720,9 @@ void MarkCompactCollector::ClearAndDeoptimizeDependentCode(
     ASSERT(entries->is_code_at(i));
     Code* code = entries->code_at(i);
 
-    if (IsMarked(code) && !code->marked_for_deoptimization()) {
+    if (code->is_weak_stub()) {

[Toon Verwaest, 2014/04/03 15:18:36]

Also IsMarked(code)?

[ulan, 2014/04/03 15:40:26]

Good catch, done.

+      IC::InvalidateMapsAndHandlers(code);
+    } else if (IsMarked(code) && !code->marked_for_deoptimization()) {
       code->set_marked_for_deoptimization(true);
       code->InvalidateEmbeddedObjects();
       have_code_to_deoptimize_ = true;
@@ -3409,7 +3411,7 @@ void MarkCompactCollector::InvalidateCode(Code* code) {
 
 // Return true if the given code is deoptimized or will be deoptimized.
 bool MarkCompactCollector::WillBeDeoptimized(Code* code) {
-  return code->marked_for_deoptimization();
+  return code->is_optimized_code() && code->marked_for_deoptimization();
 }