Use separate random number generator for each randomization pass

src/IceTargetLoweringMIPS32.cpp

 //===- subzero/src/IceTargetLoweringMIPS32.cpp - MIPS32 lowering ----------===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
@@ skipping 589 matching lines @@
 
 void TargetMIPS32::lowerLoad(const InstLoad *Inst) {
   (void)Inst;
   UnimplementedError(Func->getContext()->getFlags());
 }
 
 void TargetMIPS32::doAddressOptLoad() {
   UnimplementedError(Func->getContext()->getFlags());
 }
 
-void TargetMIPS32::randomlyInsertNop(float Probability) {
-  RandomNumberGeneratorWrapper RNG(Ctx->getRNG());
-  if (RNG.getTrueWithProbability(Probability)) {
+void TargetMIPS32::randomlyInsertNop(float Probability,
+                                     RandomNumberGenerator &RNG) {
+  RandomNumberGeneratorWrapper RNGW(RNG);
+  if (RNGW.getTrueWithProbability(Probability)) {
     UnimplementedError(Func->getContext()->getFlags());
   }
 }
 
 void TargetMIPS32::lowerPhi(const InstPhi * /*Inst*/) {
   Func->setError("Phi found in regular instruction list");
 }
 
 void TargetMIPS32::lowerRet(const InstRet *Inst) {
   Variable *Reg = nullptr;
@@ skipping 36 matching lines @@
 void TargetMIPS32::postLower() {
   if (Ctx->getFlags().getOptLevel() == Opt_m1)
     return;
   // Find two-address non-SSA instructions where Dest==Src0, and set
   // the DestNonKillable flag to keep liveness analysis consistent.
   UnimplementedError(Func->getContext()->getFlags());
 }
 
 void TargetMIPS32::makeRandomRegisterPermutation(
     llvm::SmallVectorImpl<int32_t> &Permutation,
-    const llvm::SmallBitVector &ExcludeRegisters) const {
+    const llvm::SmallBitVector &ExcludeRegisters, uint64_t Salt) const {
   (void)Permutation;
   (void)ExcludeRegisters;
+  (void)Salt;
   UnimplementedError(Func->getContext()->getFlags());
 }
 
 /* TODO(jvoung): avoid duplicate symbols with multiple targets.
 void ConstantUndef::emitWithoutDollar(GlobalContext *) const {
   llvm_unreachable("Not expecting to emitWithoutDollar undef");
 }
 
 void ConstantUndef::emit(GlobalContext *) const {
   llvm_unreachable("undef value encountered by emitter.");
@@ skipping 32 matching lines @@
 void TargetDataMIPS32::lowerJumpTables() {
   if (Ctx->getFlags().getDisableTranslation())
     return;
   UnimplementedError(Ctx->getFlags());
 }
 
 TargetHeaderMIPS32::TargetHeaderMIPS32(GlobalContext *Ctx)
     : TargetHeaderLowering(Ctx) {}
 
 } // end of namespace Ice