Use separate random number generator for each randomization pass

src/IceCfgNode.cpp

 //===- subzero/src/IceCfgNode.cpp - Basic block (node) implementation -----===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
@@ skipping 478 matching lines @@
 // instruction and delete the old.
 void CfgNode::doAddressOpt() {
   TargetLowering *Target = Func->getTarget();
   LoweringContext &Context = Target->getContext();
   Context.init(this);
   while (!Context.atEnd()) {
     Target->doAddressOpt();
   }
 }
 
-void CfgNode::doNopInsertion() {
+void CfgNode::doNopInsertion(RandomNumberGenerator &RNG) {
   TargetLowering *Target = Func->getTarget();
   LoweringContext &Context = Target->getContext();
   Context.init(this);
   Context.setInsertPoint(Context.getCur());
   // Do not insert nop in bundle locked instructions.
   bool PauseNopInsertion = false;
   while (!Context.atEnd()) {
     if (llvm::isa<InstBundleLock>(Context.getCur())) {
       PauseNopInsertion = true;
     } else if (llvm::isa<InstBundleUnlock>(Context.getCur())) {
       PauseNopInsertion = false;
     }
     if (!PauseNopInsertion)
-      Target->doNopInsertion();
+      Target->doNopInsertion(RNG);
     // Ensure Cur=Next, so that the nops are inserted before the current
     // instruction rather than after.
     Context.advanceCur();
     Context.advanceNext();
   }
 }
 
 // Drives the target lowering.  Passes the current instruction and the
 // next non-deleted instruction for target lowering.
 void CfgNode::genCode() {
@@ skipping 753 matching lines @@
   InstIntrinsicCall *Inst = InstIntrinsicCall::create(
       Func, 5, Func->makeVariable(IceType_i64), RMWI64Name, Info->Info);
   Inst->addArg(AtomicRMWOp);
   Inst->addArg(Counter);
   Inst->addArg(One);
   Inst->addArg(OrderAcquireRelease);
   Insts.push_front(Inst);
 }
 
 } // end of namespace Ice