[wasm] Implement simd lowering for I16x8

src/compiler/simd-scalar-lowering.h

 // 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_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/js-graph.h"
@@ skipping 10 matching lines @@
   SimdScalarLowering(JSGraph* jsgraph,
                      Signature<MachineRepresentation>* signature);
 
   void LowerGraph();
 
   int GetParameterCountAfterLowering();
 
  private:
   enum class State : uint8_t { kUnvisited, kOnStack, kVisited };
 
-  enum class SimdType : uint8_t { kInt32, kFloat32, kSimd1x4 };
+  enum class SimdType : uint8_t {
+    kInt32,
+    kFloat32,
+    kSimd1x4,
+    kInt16,
+    kSimd1x8

[gdeepti, 2017/04/25 20:29:58]

Perhaps maintain the same ordering for ops as in
instruction-selector/wasm-opcodes etc.? (F32x4, I32x4, I16x8, I8x16, Generic
S128 types).

[aseemgarg, 2017/04/26 23:02:01]

Done.

+  };
 
-  static const int kMaxLanes = 4;
-  static const int kLaneWidth = 16 / kMaxLanes;
+  static const int kNumLanes32 = 4;
+  static const int kNumLanes16 = 8;
+  static const int32_t kMask16 = 0xffff;
+  static const int32_t kShift16 = 16;
 
   struct Replacement {
-    Node* node[kMaxLanes];
-    SimdType type;  // represents what input type is expected
+    Node** node;
+    SimdType type;  // represents output type
+    int num_replacements;
   };
 
   struct NodeState {
     Node* node;
     int input_index;
   };
 
   Zone* zone() const { return jsgraph_->zone(); }
   Graph* graph() const { return jsgraph_->graph(); }
   MachineOperatorBuilder* machine() const { return jsgraph_->machine(); }
   CommonOperatorBuilder* common() const { return jsgraph_->common(); }
   Signature<MachineRepresentation>* signature() const { return signature_; }
 
   void LowerNode(Node* node);
   bool DefaultLowering(Node* node);
 
-  void ReplaceNode(Node* old, Node** new_nodes);
+  int NumLanes(SimdType type);
+  void ReplaceNode(Node* old, Node** new_nodes, int count);
   bool HasReplacement(size_t index, Node* node);
   Node** GetReplacements(Node* node);
+  int ReplacementCount(Node* node);
+  void Float32ToInt32(Node** replacements, Node** result);
+  void Int32ToFloat32(Node** replacements, Node** result);
+  void Int32ToInt16(Node** replacements, Node** result);
+  void Int16ToInt32(Node** replacements, Node** result);
   Node** GetReplacementsWithType(Node* node, SimdType type);
   SimdType ReplacementType(Node* node);
   void PreparePhiReplacement(Node* phi);
   void SetLoweredType(Node* node, Node* output);
-  void GetIndexNodes(Node* index, Node** new_indices);
+  void GetIndexNodes(Node* index, Node** new_indices, SimdType type);
   void LowerLoadOp(MachineRepresentation rep, Node* node,
-                   const Operator* load_op);
+                   const Operator* load_op, SimdType type);
   void LowerStoreOp(MachineRepresentation rep, Node* node,
                     const Operator* store_op, SimdType rep_type);
   void LowerBinaryOp(Node* node, SimdType input_rep_type, const Operator* op,
                      bool invert_inputs = false);
+  Node* FixUpperBits(Node* input, int32_t shift);
+  void LowerBinaryOpForSmallInt(Node* node, SimdType input_rep_type,
+                                const Operator* op);
+  Node* Mask(Node* input, int32_t mask);
+  void LowerSaturateBinaryOp(Node* node, SimdType input_rep_type,
+                             const Operator* op, bool is_signed);
   void LowerUnaryOp(Node* node, SimdType input_rep_type, const Operator* op);
-  void LowerIntMinMax(Node* node, const Operator* op, bool is_max);
+  void LowerIntMinMax(Node* node, const Operator* op, bool is_max,
+                      SimdType type);
   void LowerConvertFromFloat(Node* node, bool is_signed);
-  void LowerShiftOp(Node* node, const Operator* op);
+  void LowerShiftOp(Node* node, SimdType type);
   Node* BuildF64Trunc(Node* input);
   void LowerNotEqual(Node* node, SimdType input_rep_type, const Operator* op);
 
   JSGraph* const jsgraph_;
   NodeMarker<State> state_;
   ZoneDeque<NodeState> stack_;
   Replacement* replacements_;
   Signature<MachineRepresentation>* signature_;
   Node* placeholder_;
   int parameter_count_after_lowering_;
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_SIMD_SCALAR_LOWERING_H_