Subzero: Randomly insert nops.

src/IceInstX8632.h

Index: src/IceInstX8632.h
diff --git a/src/IceInstX8632.h b/src/IceInstX8632.h
index 64ce4a0035f80ab1b0a1dad6cc3360359f28c861..834e061374b28acc6c4e679c079eea49153f0cd6 100644
--- a/src/IceInstX8632.h
+++ b/src/IceInstX8632.h
@@ -175,6 +175,7 @@ public:
     Mulps,
     Mulss,
     Neg,
+    Nop,
     Or,
     Padd,
     Pand,
@@ -1060,6 +1061,28 @@ private:
   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: