Implement optional turbofan UnalignedLoad and UnalignedStore operators

src/compiler/int64-lowering.cc

Index: src/compiler/int64-lowering.cc
diff --git a/src/compiler/int64-lowering.cc b/src/compiler/int64-lowering.cc
index 403d4c961cfc3ebf6668c674138bda1cd1ea6546..7a358cfbf51dbf2a5a087dc1b01bc8fa240d9f9d 100644
--- a/src/compiler/int64-lowering.cc
+++ b/src/compiler/int64-lowering.cc
@@ -126,6 +126,38 @@ void Int64Lowering::LowerNode(Node* node) {
       }
       break;
     }
+    case IrOpcode::kUnalignedLoad: {

[titzer, 2016/03/29 08:42:48]

Can you factor out the common code between load/unaligned_load and
store/unaligned_store?

+      UnalignedLoadRepresentation load_rep =
+          UnalignedLoadRepresentationOf(node->op());
+
+      if (load_rep.representation() == MachineRepresentation::kWord64) {
+        Node* base = node->InputAt(0);
+        Node* index = node->InputAt(1);
+        Node* index_high =
+            graph()->NewNode(machine()->Int32Add(), index,
+                             graph()->NewNode(common()->Int32Constant(4)));
+
+        const Operator* load_op =
+            machine()->UnalignedLoad(MachineType::Int32()).op();
+        Node* high_node;
+        if (node->InputCount() > 2) {
+          Node* effect_high = node->InputAt(2);
+          Node* control_high = node->InputAt(3);
+          high_node = graph()->NewNode(load_op, base, index_high, effect_high,
+                                       control_high);
+          // change the effect change from old_node --> old_effect to
+          // old_node --> high_node --> old_effect.
+          node->ReplaceInput(2, high_node);
+        } else {
+          high_node = graph()->NewNode(load_op, base, index_high);
+        }
+        NodeProperties::ChangeOp(node, load_op);
+        ReplaceNode(node, node, high_node);
+      } else {
+        DefaultLowering(node);
+      }
+      break;
+    }
     case IrOpcode::kStore: {
       StoreRepresentation store_rep = StoreRepresentationOf(node->op());
       if (store_rep.representation() == MachineRepresentation::kWord64) {
@@ -170,6 +202,46 @@ void Int64Lowering::LowerNode(Node* node) {
       }
       break;
     }
+    case IrOpcode::kUnalignedStore: {
+      UnalignedStoreRepresentation store_rep =
+          UnalignedStoreRepresentationOf(node->op());
+      if (store_rep == MachineRepresentation::kWord64) {
+        Node* base = node->InputAt(0);
+        Node* index = node->InputAt(1);
+        Node* index_high =
+            graph()->NewNode(machine()->Int32Add(), index,
+                             graph()->NewNode(common()->Int32Constant(4)));
+
+        Node* value = node->InputAt(2);
+        DCHECK(HasReplacementLow(value));
+        DCHECK(HasReplacementHigh(value));
+
+        const Operator* store_op =
+            machine()->UnalignedStore(MachineRepresentation::kWord32).op();
+
+        Node* high_node;
+        if (node->InputCount() > 3) {
+          Node* effect_high = node->InputAt(3);
+          Node* control_high = node->InputAt(4);
+          high_node = graph()->NewNode(store_op, base, index_high,
+                                       GetReplacementHigh(value), effect_high,
+                                       control_high);
+          node->ReplaceInput(3, high_node);
+
+        } else {
+          high_node = graph()->NewNode(store_op, base, index_high,
+                                       GetReplacementHigh(value));
+        }
+
+        node->ReplaceInput(2, GetReplacementLow(value));
+        NodeProperties::ChangeOp(node, store_op);
+        ReplaceNode(node, node, high_node);
+      } else {
+        DefaultLowering(node);
+      }
+      break;
+    }
+
     case IrOpcode::kStart: {
       int parameter_count = GetParameterCountAfterLowering(signature());
       // Only exchange the node if the parameter count actually changed.