Add support for untagged LoadField, StoreField, LoadElement, and StoreElement simplfied operators. …

src/compiler/simplified-lowering.cc

Index: src/compiler/simplified-lowering.cc
diff --git a/src/compiler/simplified-lowering.cc b/src/compiler/simplified-lowering.cc
index 44eed8fddfd64d417c749b94e50f58ea82dd50cd..5a99768bc5c4fd4d7b9b28ab97ad77fb910b16a2 100644
--- a/src/compiler/simplified-lowering.cc
+++ b/src/compiler/simplified-lowering.cc
@@ -193,9 +193,10 @@ void SimplifiedLowering::DoChangeBitToBool(Node* node, Node* effect,
 
 
 static WriteBarrierKind ComputeWriteBarrierKind(
-    MachineRepresentation representation, Type* type) {
+    bool base_is_tagged, MachineRepresentation representation, Type* type) {

[Benedikt Meurer, 2014/08/04 12:18:31]

Nit: Use that same enum here as well.

   // TODO(turbofan): skip write barriers for Smis, etc.
-  if (representation == kMachineTagged) {
+  if (base_is_tagged && representation == kMachineTagged) {
+    // Write barriers are only for writes into heap objects (i.e. tagged base).
     return kFullWriteBarrier;
   }
   return kNoWriteBarrier;
@@ -205,19 +206,17 @@ static WriteBarrierKind ComputeWriteBarrierKind(
 void SimplifiedLowering::DoLoadField(Node* node, Node* effect, Node* control) {
   const FieldAccess& access = FieldAccessOf(node->op());
   node->set_op(machine_.Load(access.representation));
-  Node* offset =
-      graph()->NewNode(common()->Int32Constant(access.offset - kHeapObjectTag));
+  Node* offset = jsgraph()->Int32Constant(access.offset - access.tag());
   node->InsertInput(zone(), 1, offset);
 }
 
 
 void SimplifiedLowering::DoStoreField(Node* node, Node* effect, Node* control) {
   const FieldAccess& access = FieldAccessOf(node->op());
-  WriteBarrierKind kind =
-      ComputeWriteBarrierKind(access.representation, access.type);
+  WriteBarrierKind kind = ComputeWriteBarrierKind(
+      access.tag() != 0, access.representation, access.type);
   node->set_op(machine_.Store(access.representation, kind));
-  Node* offset =
-      graph()->NewNode(common()->Int32Constant(access.offset - kHeapObjectTag));
+  Node* offset = jsgraph()->Int32Constant(access.offset - access.tag());
   node->InsertInput(zone(), 1, offset);
 }
 
@@ -247,15 +246,13 @@ Node* SimplifiedLowering::ComputeIndex(const ElementAccess& access,
       break;
   }
   if (element_size != 1) {
-    index = graph()->NewNode(
-        machine()->Int32Mul(),
-        graph()->NewNode(common()->Int32Constant(element_size)), index);
+    index = graph()->NewNode(machine()->Int32Mul(),
+                             jsgraph()->Int32Constant(element_size), index);
   }
-  int fixed_offset = access.header_size - kHeapObjectTag;
+  int fixed_offset = access.header_size - access.tag();
   if (fixed_offset == 0) return index;
-  return graph()->NewNode(
-      machine()->Int32Add(),
-      graph()->NewNode(common()->Int32Constant(fixed_offset)), index);
+  return graph()->NewNode(machine()->Int32Add(),
+                          jsgraph()->Int32Constant(fixed_offset), index);
 }
 
 
@@ -270,8 +267,8 @@ void SimplifiedLowering::DoLoadElement(Node* node, Node* effect,
 void SimplifiedLowering::DoStoreElement(Node* node, Node* effect,
                                         Node* control) {
   const ElementAccess& access = ElementAccessOf(node->op());
-  WriteBarrierKind kind =
-      ComputeWriteBarrierKind(access.representation, access.type);
+  WriteBarrierKind kind = ComputeWriteBarrierKind(
+      access.tag() != 0, access.representation, access.type);
   node->set_op(machine_.Store(access.representation, kind));
   node->ReplaceInput(1, ComputeIndex(access, node->InputAt(1)));
 }