[wasm] simd scalar lowering F32x4Add and I32x4Add

src/compiler/simd-scalar-lowering.h

-// Copyright 2014 the V8 project authors. All rights reserved.
+// Copyright 2016 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#ifndef V8_COMPILER_INT64_LOWERING_H_
-#define V8_COMPILER_INT64_LOWERING_H_
+#ifndef V8_COMPILER_SIMD_SCALAR_LOWERING_H_
+#define V8_COMPILER_SIMD_SCALAR_LOWERING_H_
 
 #include "src/compiler/common-operator.h"
 #include "src/compiler/graph.h"
 #include "src/compiler/machine-operator.h"
 #include "src/compiler/node-marker.h"
 #include "src/zone/zone-containers.h"
 
 namespace v8 {
 namespace internal {
 namespace compiler {
 
-class Int64Lowering {
+class SimdScalarLowering {
  public:
-  Int64Lowering(Graph* graph, MachineOperatorBuilder* machine,
-                CommonOperatorBuilder* common, Zone* zone,
-                Signature<MachineRepresentation>* signature);
+  SimdScalarLowering(Graph* graph, MachineOperatorBuilder* machine,
+                     CommonOperatorBuilder* common, Zone* zone,
+                     Signature<MachineRepresentation>* signature);
 
   void LowerGraph();
 
   static int GetParameterCountAfterLowering(
       Signature<MachineRepresentation>* signature);
 
-  static const int kLowerWordOffset;
-  static const int kHigherWordOffset;
-
  private:
   enum class State : uint8_t { kUnvisited, kOnStack, kVisited };
 
+  enum class SimdType : uint8_t { kInt32, kFloat32 };
+
+  static const size_t kMaxLanes = 4;
+
   struct Replacement {
-    Node* low;
-    Node* high;
+    Node* node[kMaxLanes];
+    SimdType type;  // represents what input type is expected
   };
 
   Zone* zone() const { return zone_; }
   Graph* graph() const { return graph_; }
   MachineOperatorBuilder* machine() const { return machine_; }
   CommonOperatorBuilder* common() const { return common_; }
   Signature<MachineRepresentation>* signature() const { return signature_; }
 
-  void PrepareReplacements(Node* node);
-  void PushNode(Node* node);
   void LowerNode(Node* node);
   bool DefaultLowering(Node* node);
-  void LowerComparison(Node* node, const Operator* signed_op,
-                       const Operator* unsigned_op);
-  void PrepareProjectionReplacements(Node* node);
 
-  void ReplaceNode(Node* old, Node* new_low, Node* new_high);
-  bool HasReplacementLow(Node* node);
-  Node* GetReplacementLow(Node* node);
-  bool HasReplacementHigh(Node* node);
-  Node* GetReplacementHigh(Node* node);
+  void ReplaceNode(Node* old, Node** new_nodes);
+  bool HasReplacement(size_t index, Node* node);
+  Node** GetReplacements(Node* node);
+  Node** GetReplacementsWithType(Node* node, SimdType type);
+  SimdType ReplacementType(Node* node);
   void PreparePhiReplacement(Node* phi);
-  void GetIndexNodes(Node* index, Node*& index_low, Node*& index_high);
+  void SetLoweredType(Node* node, Node* output);
 
   struct NodeState {
     Node* node;
     int input_index;
   };
 
   Zone* zone_;
   Graph* const graph_;
   MachineOperatorBuilder* machine_;
   CommonOperatorBuilder* common_;
   NodeMarker<State> state_;
   ZoneDeque<NodeState> stack_;
   Replacement* replacements_;
   Signature<MachineRepresentation>* signature_;
   Node* placeholder_;
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
-#endif  // V8_COMPILER_INT64_LOWERING_H_
+#endif  // V8_COMPILER_SIMD_SCALAR_LOWERING_H_