Guard against undefined fields in global context.

BUG=v8:1860
TEST=
R=vegorov@chromium.org

Review URL: http://codereview.chromium.org/8917014

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@10243 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/assembler.cc

@@ -817,11 +817,6 @@ ExternalReference ExternalReference::compute_output_frames_function(
 }
 
 
-ExternalReference ExternalReference::global_contexts_list(Isolate* isolate) {
-  return ExternalReference(isolate->heap()->global_contexts_list_address());
-}
-
-
 ExternalReference ExternalReference::keyed_lookup_cache_keys(Isolate* isolate) {
   return ExternalReference(isolate->keyed_lookup_cache()->keys_address());
 }

src/assembler.h

@@ -590,7 +590,6 @@ class ExternalReference BASE_EMBEDDED {
   // Deoptimization support.
   static ExternalReference new_deoptimizer_function(Isolate* isolate);
   static ExternalReference compute_output_frames_function(Isolate* isolate);
-  static ExternalReference global_contexts_list(Isolate* isolate);
 
   // Static data in the keyed lookup cache.
   static ExternalReference keyed_lookup_cache_keys(Isolate* isolate);

src/deoptimizer.cc

@@ -264,11 +264,16 @@ void Deoptimizer::VisitAllOptimizedFunctions(
   AssertNoAllocation no_allocation;
 
   // Run through the list of all global contexts and deoptimize.
-  Object* global = Isolate::Current()->heap()->global_contexts_list();
-  while (!global->IsUndefined()) {
-    VisitAllOptimizedFunctionsForGlobalObject(Context::cast(global)->global(),
+  Object* context = Isolate::Current()->heap()->global_contexts_list();
+  while (!context->IsUndefined()) {
+    // GC can happen when the context is not fully initialized,
+    // so the global field of the context can be undefined.
+    Object* global = Context::cast(context)->get(Context::GLOBAL_INDEX);
+    if (!global->IsUndefined()) {
+      VisitAllOptimizedFunctionsForGlobalObject(JSObject::cast(global),
                                                 visitor);
-    global = Context::cast(global)->get(Context::NEXT_CONTEXT_LINK);
+    }
+    context = Context::cast(context)->get(Context::NEXT_CONTEXT_LINK);
   }
 }
 

src/heap.cc

@@ -642,14 +642,18 @@ void Heap::ClearJSFunctionResultCaches() {
 
   Object* context = global_contexts_list_;
   while (!context->IsUndefined()) {
-    // Get the caches for this context:
-    FixedArray* caches =
-      Context::cast(context)->jsfunction_result_caches();
+    // Get the caches for this context. GC can happen when the context
+    // is not fully initialized, so the caches can be undefined.
+    Object* caches_or_undefined =
+        Context::cast(context)->get(Context::JSFUNCTION_RESULT_CACHES_INDEX);
+    if (!caches_or_undefined->IsUndefined()) {
+      FixedArray* caches = FixedArray::cast(caches_or_undefined);
       // Clear the caches:
       int length = caches->length();
       for (int i = 0; i < length; i++) {
         JSFunctionResultCache::cast(caches->get(i))->Clear();
       }
+    }
     // Get the next context:
     context = Context::cast(context)->get(Context::NEXT_CONTEXT_LINK);
   }
@@ -665,7 +669,13 @@ void Heap::ClearNormalizedMapCaches() {
 
   Object* context = global_contexts_list_;
   while (!context->IsUndefined()) {
-    Context::cast(context)->normalized_map_cache()->Clear();
+    // GC can happen when the context is not fully initialized,
+    // so the cache can be undefined.
+    Object* cache =
+        Context::cast(context)->get(Context::NORMALIZED_MAP_CACHE_INDEX);
+    if (!cache->IsUndefined()) {
+      NormalizedMapCache::cast(cache)->Clear();
+    }
     context = Context::cast(context)->get(Context::NEXT_CONTEXT_LINK);
   }
 }

src/incremental-marking.cc

@@ -677,12 +677,17 @@ void IncrementalMarking::Hurry() {
 
   Object* context = heap_->global_contexts_list();
   while (!context->IsUndefined()) {
-    NormalizedMapCache* cache = Context::cast(context)->normalized_map_cache();
+    // GC can happen when the context is not fully initialized,
+    // so the cache can be undefined.
+    HeapObject* cache = HeapObject::cast(
+        Context::cast(context)->get(Context::NORMALIZED_MAP_CACHE_INDEX));
+    if (!cache->IsUndefined()) {
       MarkBit mark_bit = Marking::MarkBitFrom(cache);
       if (Marking::IsGrey(mark_bit)) {
         Marking::GreyToBlack(mark_bit);
         MemoryChunk::IncrementLiveBytes(cache->address(), cache->Size());
       }
+    }
     context = Context::cast(context)->get(Context::NEXT_CONTEXT_LINK);
   }
 }