Subzero: Randomly insert nops.

src/IceInstX8632.h

Index: src/IceInstX8632.h
diff --git a/src/IceInstX8632.h b/src/IceInstX8632.h
index a2fd7dccf3d6792a312be4b2f2df490ed4cca9dd..cf294d76ff1ff7cda2798a49301646b86c78c175 100644
--- a/src/IceInstX8632.h
+++ b/src/IceInstX8632.h
@@ -175,6 +175,7 @@ public:
     Mulps,
     Mulss,
     Neg,
+    Nop,
     Or,
     Padd,
     Pand,
@@ -1076,6 +1077,26 @@ private:
   virtual ~InstX8632Movzx() {}
 };
 
+// Nop instructions of varying length
+class InstX8632Nop: public InstX8632 {
+public:
+  static InstX8632Nop *create(Cfg *Func, SizeT Length) {
+    return new (Func->allocate<InstX8632Nop>())
+        InstX8632Nop(Func, Length);
+  }
+  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() {}
+
+  SizeT Length;
+};
+
 // Fld - load a value onto the x87 FP stack.
 class InstX8632Fld : public InstX8632 {
 public: