Use separate random number generator for each randomization pass

src/IceTargetLoweringX86Base.h

 //===- subzero/src/IceTargetLoweringX86Base.h - x86 lowering ----*- C++ -*-===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
@@ skipping 162 matching lines @@
   void lowerPhi(const InstPhi *Inst) override;
   void lowerSelect(const InstSelect *Inst) override;
   void lowerStore(const InstStore *Inst) override;
   void lowerSwitch(const InstSwitch *Inst) override;
   void lowerUnreachable(const InstUnreachable *Inst) override;
   void lowerOther(const Inst *Instr) override;
   void lowerRMW(const typename Traits::Insts::FakeRMW *RMW);
   void prelowerPhis() override;
   void doAddressOptLoad() override;
   void doAddressOptStore() override;
-  void randomlyInsertNop(float Probability) override;
+  void randomlyInsertNop(float Probability,
+                         RandomNumberGenerator &RNG) override;
 
   /// Naive lowering of cmpxchg.
   void lowerAtomicCmpxchg(Variable *DestPrev, Operand *Ptr, Operand *Expected,
                           Operand *Desired);
   /// Attempt a more optimized lowering of cmpxchg. Returns true if optimized.
   bool tryOptimizedCmpxchgCmpBr(Variable *DestPrev, Operand *Ptr,
                                 Operand *Expected, Operand *Desired);
   void lowerAtomicRMW(Variable *Dest, uint32_t Operation, Operand *Ptr,
                       Operand *Val);
   void lowerCountZeros(bool Cttz, Type Ty, Variable *Dest, Operand *FirstVal,
@@ skipping 500 matching lines @@
   }
 
   BoolFolding FoldingInfo;
 };
 } // end of namespace X86Internal
 } // end of namespace Ice
 
 #include "IceTargetLoweringX86BaseImpl.h"
 
 #endif // SUBZERO_SRC_ICETARGETLOWERINGX86BASE_H