[wasm] Implement simd lowering for I8x16

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 14 matching lines @@
 
   int GetParameterCountAfterLowering();
 
  private:
   enum class State : uint8_t { kUnvisited, kOnStack, kVisited };
 
   enum class SimdType : uint8_t {
     kFloat32x4,
     kInt32x4,
     kInt16x8,
+    kInt8x16,
     kSimd1x4,
-    kSimd1x8
+    kSimd1x8,
+    kSimd1x16
   };
 
 #if defined(V8_TARGET_BIG_ENDIAN)
   static constexpr int kLaneOffsets[16] = {15, 14, 13, 12, 11, 10, 9, 8,
                                            7,  6,  5,  4,  3,  2,  1, 0};
 #else
   static constexpr int kLaneOffsets[16] = {0, 1, 2,  3,  4,  5,  6,  7,
                                            8, 9, 10, 11, 12, 13, 14, 15};
 #endif
   struct Replacement {
@@ skipping 55 matching lines @@
   Signature<MachineRepresentation>* signature_;
   Node* placeholder_;
   int parameter_count_after_lowering_;
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_SIMD_SCALAR_LOWERING_H_