Subzero: Randomly insert nops.

src/IceInstX8632.h

 //===- subzero/src/IceInstX8632.h - Low-level x86 instructions --*- C++ -*-===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file declares the InstX8632 and OperandX8632 classes and
@@ skipping 157 matching lines @@
     Movd,
     Movp,
     Movq,
     Movss,
     Movsx,
     Movzx,
     Mul,
     Mulps,
     Mulss,
     Neg,
+    Nop,
     Or,
     Padd,
     Pand,
     Pandn,
     Pblendvb,
     Pcmpeq,
     Pcmpgt,
     Pextr,
     Pinsr,
     Pmull,
@@ skipping 865 matching lines @@
   virtual void dump(const Cfg *Func) const;
   static bool classof(const Inst *Inst) { return isClassof(Inst, Movzx); }
 
 private:
   InstX8632Movzx(Cfg *Func, Variable *Dest, Operand *Source);
   InstX8632Movzx(const InstX8632Movzx &) LLVM_DELETED_FUNCTION;
   InstX8632Movzx &operator=(const InstX8632Movzx &) LLVM_DELETED_FUNCTION;
   virtual ~InstX8632Movzx() {}
 };
 
+// Nop instructions of varying length
+class InstX8632Nop : public InstX8632 {
+public:
+  // TODO: Replace with enum.
+  typedef unsigned NopVariant;
+
+  static InstX8632Nop *create(Cfg *Func, NopVariant Variant) {
+    return new (Func->allocate<InstX8632Nop>()) InstX8632Nop(Func, Variant);
+  }
+  virtual void emit(const Cfg *Func) const;
+  virtual void dump(const Cfg *Func) const;
+  static bool classof(const Inst *Inst) { return isClassof(Inst, Nop); }
+
+private:
+  InstX8632Nop(Cfg *Func, SizeT Length);
+  InstX8632Nop(const InstX8632Nop &) LLVM_DELETED_FUNCTION;
+  InstX8632Nop &operator=(const InstX8632Nop &) LLVM_DELETED_FUNCTION;
+  virtual ~InstX8632Nop() {}
+
+  NopVariant Variant;
+};
+
 // Fld - load a value onto the x87 FP stack.
 class InstX8632Fld : public InstX8632 {
 public:
   static InstX8632Fld *create(Cfg *Func, Operand *Src) {
     return new (Func->allocate<InstX8632Fld>()) InstX8632Fld(Func, Src);
   }
   virtual void emit(const Cfg *Func) const;
   virtual void dump(const Cfg *Func) const;
   static bool classof(const Inst *Inst) { return isClassof(Inst, Fld); }
 
@@ skipping 146 matching lines @@
 template <> void InstX8632Pmuludq::emit(const Cfg *Func) const;
 template <> void InstX8632Psll::emit(const Cfg *Func) const;
 template <> void InstX8632Psra::emit(const Cfg *Func) const;
 template <> void InstX8632Psub::emit(const Cfg *Func) const;
 template <> void InstX8632Sqrtss::emit(const Cfg *Func) const;
 template <> void InstX8632Subss::emit(const Cfg *Func) const;
 
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICEINSTX8632_H