Auto-sandboxing: Switch to automatic scratch register invalidation

lib/Target/X86/MCTargetDesc/X86MCNaClExpander.h

 //===- X86MCNaClExpander.h --------------------------------------*- C++ -*-===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file declares the X86MCNaClExpander class, the X86 specific
@@ skipping 16 matching lines @@
 
 namespace X86 {
 class X86MCNaClExpander : public MCNaClExpander {
 public:
   X86MCNaClExpander(const MCContext &Ctx, std::unique_ptr<MCRegisterInfo> &&RI,
                     std::unique_ptr<MCInstrInfo> &&II, bool Is64Bit)
       : MCNaClExpander(Ctx, std::move(RI), std::move(II)), Is64Bit(Is64Bit) {}
 
   bool expandInst(const MCInst &Inst, MCStreamer &Out,
                   const MCSubtargetInfo &STI) override;
+protected:
+  bool isValidScratchRegister(unsigned Reg) const override;
+
 private:
   bool Guard = false; // recursion guard
   bool Is64Bit = false;
   SmallVector<MCInst, 4> Prefixes;
 
   void emitPrefixes(MCStreamer &Out, const MCSubtargetInfo &STI);
 
   void expandIndirectBranch(const MCInst &Inst, MCStreamer &Out,
                             const MCSubtargetInfo &STI);
 
@@ skipping 26 matching lines @@
   void emitSandboxBranchReg(unsigned Reg, MCStreamer &Out,
                             const MCSubtargetInfo &STI);
   void emitIndirectJumpReg(unsigned Reg, MCStreamer &Out,
                            const MCSubtargetInfo &STI);
   void emitIndirectCallReg(unsigned Reg, MCStreamer &Out,
                            const MCSubtargetInfo &STI);
 };
 }
 }
 #endif