[wasm] Implement I32x4ReplaceLane, I32x4Add, I32x4Sub.

src/compiler/simd-scalar-lowering.cc

 // 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.
 
 #include "src/compiler/simd-scalar-lowering.h"
 #include "src/compiler/diamond.h"
 #include "src/compiler/linkage.h"
 #include "src/compiler/node-matchers.h"
 #include "src/compiler/node-properties.h"
 
@@ skipping 233 matching lines @@
       Node* rep_node[kMaxLanes];
       for (int i = 0; i < kMaxLanes; i++) {
         DCHECK(!HasReplacement(1, node->InputAt(i)));
         rep_node[i] = node->InputAt(i);
       }
       ReplaceNode(node, rep_node);
       break;
     }
 
     case IrOpcode::kInt32x4ExtractLane: {
-      Node* laneNode = node->InputAt(1);
-      DCHECK_EQ(laneNode->opcode(), IrOpcode::kInt32Constant);
-      int32_t lane = OpParameter<int32_t>(laneNode);
+      int32_t lane = OpParameter<int32_t>(node);
       Node* rep_node[kMaxLanes] = {
           GetReplacementsWithType(node->InputAt(0), rep_type)[lane], nullptr,
           nullptr, nullptr};
       ReplaceNode(node, rep_node);
       break;
     }
 
     case IrOpcode::kFloat32x4Add: {
       DCHECK(node->InputCount() == 2);
       Node** rep_left = GetReplacementsWithType(node->InputAt(0), rep_type);
@@ skipping 11 matching lines @@
       Node* rep_node[kMaxLanes];
       for (int i = 0; i < kMaxLanes; i++) {
         DCHECK(!HasReplacement(1, node->InputAt(i)));
         rep_node[i] = node->InputAt(i);
       }
       ReplaceNode(node, rep_node);
       break;
     }
 
     case IrOpcode::kFloat32x4ExtractLane: {
-      Node* laneNode = node->InputAt(1);
-      DCHECK_EQ(laneNode->opcode(), IrOpcode::kInt32Constant);
-      int32_t lane = OpParameter<int32_t>(laneNode);
+      int32_t lane = OpParameter<int32_t>(node);
       Node* rep_node[kMaxLanes] = {
           GetReplacementsWithType(node->InputAt(0), rep_type)[lane], nullptr,
           nullptr, nullptr};
       ReplaceNode(node, rep_node);
       break;
     }
 
     default: { DefaultLowering(node); }
   }
 }
@@ skipping 100 matching lines @@
       } else {
         UNREACHABLE();
       }
     }
     ReplaceNode(phi, rep_nodes);
   }
 }
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8