Remove more superfluous write barriers.

Review URL: http://codereview.chromium.org/8595008

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@10032 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/objects.cc

@@ -9962,8 +9962,8 @@ void FixedArray::SwapPairs(FixedArray* numbers, int i, int j) {
   set(j, temp);
   if (this != numbers) {
     temp = numbers->get(i);
-    numbers->set(i, numbers->get(j));
-    numbers->set(j, temp);
+    numbers->set(i, Smi::cast(numbers->get(j)));
+    numbers->set(j, Smi::cast(temp));
   }
 }
 

src/runtime.cc

@@ -1794,11 +1794,14 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_RegExpInitializeObject) {
       JSFunction::cast(constructor)->initial_map() == map) {
     // If we still have the original map, set in-object properties directly.
     regexp->InObjectPropertyAtPut(JSRegExp::kSourceFieldIndex, source);
-    // TODO(lrn): Consider skipping write barrier on booleans as well.
-    // Both true and false should be in oldspace at all times.
-    regexp->InObjectPropertyAtPut(JSRegExp::kGlobalFieldIndex, global);
-    regexp->InObjectPropertyAtPut(JSRegExp::kIgnoreCaseFieldIndex, ignoreCase);
-    regexp->InObjectPropertyAtPut(JSRegExp::kMultilineFieldIndex, multiline);
+    // Both true and false are immovable immortal objects so no need for write
+    // barrier.
+    regexp->InObjectPropertyAtPut(
+        JSRegExp::kGlobalFieldIndex, global, SKIP_WRITE_BARRIER);
+    regexp->InObjectPropertyAtPut(
+        JSRegExp::kIgnoreCaseFieldIndex, ignoreCase, SKIP_WRITE_BARRIER);
+    regexp->InObjectPropertyAtPut(
+        JSRegExp::kMultilineFieldIndex, multiline, SKIP_WRITE_BARRIER);
     regexp->InObjectPropertyAtPut(JSRegExp::kLastIndexFieldIndex,
                                   Smi::FromInt(0),
                                   SKIP_WRITE_BARRIER);  // It's a Smi.

src/spaces.cc

@@ -1658,14 +1658,14 @@ void FreeListNode::set_size(Heap* heap, int size_in_bytes) {
   // field and a next pointer, we give it a filler map that gives it the
   // correct size.
   if (size_in_bytes > FreeSpace::kHeaderSize) {
-    set_map(heap->raw_unchecked_free_space_map());
+    set_map_unsafe(heap->raw_unchecked_free_space_map());
     // Can't use FreeSpace::cast because it fails during deserialization.
     FreeSpace* this_as_free_space = reinterpret_cast<FreeSpace*>(this);
     this_as_free_space->set_size(size_in_bytes);
   } else if (size_in_bytes == kPointerSize) {
-    set_map(heap->raw_unchecked_one_pointer_filler_map());
+    set_map_unsafe(heap->raw_unchecked_one_pointer_filler_map());
   } else if (size_in_bytes == 2 * kPointerSize) {
-    set_map(heap->raw_unchecked_two_pointer_filler_map());
+    set_map_unsafe(heap->raw_unchecked_two_pointer_filler_map());
   } else {
     UNREACHABLE();
   }