Reland [heap] Avoid the use of cells to point from code to new-space objects.

src/heap/remembered-set.cc

Index: src/heap/remembered-set.cc
diff --git a/src/heap/remembered-set.cc b/src/heap/remembered-set.cc
index 0bc5e6e32401de0e4566cf81e37e9d23ab67ab04..64ee6beaedc4ec58a55746fb2a89584d02be83b2 100644
--- a/src/heap/remembered-set.cc
+++ b/src/heap/remembered-set.cc
@@ -9,6 +9,7 @@
 #include "src/heap/slot-set.h"
 #include "src/heap/spaces.h"
 #include "src/heap/store-buffer.h"
+#include "src/macro-assembler.h"
 
 namespace v8 {
 namespace internal {
@@ -16,13 +17,32 @@ namespace internal {
 template <PointerDirection direction>
 void RememberedSet<direction>::ClearInvalidSlots(Heap* heap) {
   STATIC_ASSERT(direction == OLD_TO_NEW);
-  for (MemoryChunk* chunk : *heap->old_space()) {
-    SlotSet* slots = GetSlotSet(chunk);
-    if (slots != nullptr) {
-      slots->Iterate([heap, chunk](Address addr) {
-        Object** slot = reinterpret_cast<Object**>(addr);
-        return IsValidSlot(heap, chunk, slot) ? KEEP_SLOT : REMOVE_SLOT;
-      });
+  {
+    for (MemoryChunk* chunk : *heap->old_space()) {
+      {

[Michael Lippautz, 2016/06/23 11:51:12]

nit: I too like building pyramids but there's no need for this additional scopes
;)

[ahaas, 2016/06/23 12:42:21]

done.

+        SlotSet* slots = GetSlotSet(chunk);
+        if (slots != nullptr) {
+          slots->Iterate([heap, chunk](Address addr) {
+            Object** slot = reinterpret_cast<Object**>(addr);
+            return IsValidSlot(heap, chunk, slot) ? KEEP_SLOT : REMOVE_SLOT;
+          });
+        }
+      }
+    }
+  }

[Michael Lippautz, 2016/06/23 11:51:12]

nit: You can also get rid of the outer scopes, so it could be
STATIC_ASSERT
for (...) {
...
}
for (...) {
...
}

[ahaas, 2016/06/23 12:42:21]

done.

+  {
+    for (MemoryChunk* chunk : *heap->code_space()) {
+      TypedSlotSet* slots = GetTypedSlotSet(chunk);
+      if (slots != nullptr) {
+        slots->Iterate(
+            [heap, chunk](SlotType type, Address host_addr, Address addr) {
+              if (Marking::IsBlack(Marking::MarkBitFrom(host_addr))) {
+                return KEEP_SLOT;
+              } else {
+                return REMOVE_SLOT;
+              }
+            });
+      }
     }
   }
 }