[Turbofan] Add concept of FP register aliasing on ARM 32.

src/compiler/gap-resolver.h

 // Copyright 2014 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_GAP_RESOLVER_H_
 #define V8_COMPILER_GAP_RESOLVER_H_
 
 #include "src/compiler/instruction.h"
 
 namespace v8 {
 namespace internal {
 namespace compiler {
 
 class GapResolver final {
  public:
   // Interface used by the gap resolver to emit moves and swaps.
   class Assembler {
    public:
     virtual ~Assembler() {}
 
     // Assemble move.
     virtual void AssembleMove(InstructionOperand* source,
                               InstructionOperand* destination) = 0;
     // Assemble swap.
     virtual void AssembleSwap(InstructionOperand* source,
                               InstructionOperand* destination) = 0;
   };
 
-  explicit GapResolver(Assembler* assembler) : assembler_(assembler) {}
+  explicit GapResolver(Assembler* assembler)
+      : assembler_(assembler), split_rep_(MachineRepresentation::kSimd128) {}
 
   // Resolve a set of parallel moves, emitting assembler instructions.
-  void Resolve(ParallelMove* parallel_move) const;
+  void Resolve(ParallelMove* parallel_move);
 
  private:
-  // Perform the given move, possibly requiring other moves to satisfy
-  // dependencies.
-  void PerformMove(ParallelMove* moves, MoveOperands* move) const;
+  // Performs the given move, possibly performing other moves to unblock the
+  // destination operand.
+  void PerformMove(ParallelMove* moves, MoveOperands* move);
 
   // Assembler used to emit moves and save registers.
   Assembler* const assembler_;
+
+  MachineRepresentation split_rep_;
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_GAP_RESOLVER_H_