[wasm] implement simd lowering for replaceLane, load, store and test for phi

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/machine-operator.h"
@@ skipping 35 matching lines @@
   void LowerNode(Node* node);
   bool DefaultLowering(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 SetLoweredType(Node* node, Node* output);
+  void GetIndexNodes(Node* index, Node** new_indices);

[Mircea Trofin, 2016/11/15 16:21:27]

Is 'Index' part of the SIMD nomenclature? It sounds a bit too general.

[aseemgarg, 2016/11/19 01:56:54]

It isn't. it represents index for load or store. This function simply gives
replacement (in case of simd, it will be original index, and 3 more 4 bytes
apart). 

 
   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_;
   int parameter_count_after_lowering_;
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_SIMD_SCALAR_LOWERING_H_