Use separate random number generator for each randomization pass

src/IceTargetLoweringX86BaseImpl.h

 //===- subzero/src/IceTargetLoweringX86BaseImpl.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 4114 matching lines @@
   if (Base && Addr != Base) {
     Inst->setDeleted();
     Constant *OffsetOp = Ctx->getConstantInt32(Offset);
     Addr = Traits::X86OperandMem::create(Func, Dest->getType(), Base, OffsetOp,
                                          Index, Shift, SegmentReg);
     Context.insert(InstLoad::create(Func, Dest, Addr));
   }
 }
 
 template <class Machine>
-void TargetX86Base<Machine>::randomlyInsertNop(float Probability) {
-  RandomNumberGeneratorWrapper RNG(Ctx->getRNG());
-  if (RNG.getTrueWithProbability(Probability)) {
-    _nop(RNG(Traits::X86_NUM_NOP_VARIANTS));
+void TargetX86Base<Machine>::randomlyInsertNop(float Probability,
+                                               RandomNumberGenerator &RNG) {
+  RandomNumberGeneratorWrapper RNGW(RNG);
+  if (RNGW.getTrueWithProbability(Probability)) {
+    _nop(RNGW(Traits::X86_NUM_NOP_VARIANTS));
   }
 }
 
 template <class Machine>
 void TargetX86Base<Machine>::lowerPhi(const InstPhi * /*Inst*/) {
   Func->setError("Phi found in regular instruction list");
 }
 
 template <class Machine>
 void TargetX86Base<Machine>::lowerSelect(const InstSelect *Inst) {
@@ skipping 983 matching lines @@
       //  => Reg
       // If we have already assigned a phy register, we must come from
       // andvancedPhiLowering()=>lowerAssign(). In this case we should reuse
       // the assigned register as this assignment is that start of its use-def
       // chain. So we add RegNum argument here.
       // Note we use 'lea' instruction instead of 'xor' to avoid affecting
       // the flags.
       Variable *Reg = makeReg(IceType_i32, RegNum);
       ConstantInteger32 *Integer = llvm::cast<ConstantInteger32>(Immediate);
       uint32_t Value = Integer->getValue();
-      uint32_t Cookie = Ctx->getRandomizationCookie();
+      uint32_t Cookie = Func->getConstantBlindingCookie();
       _mov(Reg, Ctx->getConstantInt(IceType_i32, Cookie + Value));
       Constant *Offset = Ctx->getConstantInt(IceType_i32, 0 - Cookie);
       _lea(Reg, Traits::X86OperandMem::create(Func, IceType_i32, Reg, Offset,
                                               nullptr, 0));
       // make sure liveness analysis won't kill this variable, otherwise a
       // liveness assertion will be triggered.
       _set_dest_nonkillable();
       if (Immediate->getType() != IceType_i32) {
         Variable *TruncReg = makeReg(Immediate->getType(), RegNum);
         _mov(TruncReg, Reg);
@@ skipping 58 matching lines @@
           RPI_Randomize) {
         // blind the constant offset
         // FROM:
         //  offset[base, index, shift]
         // TO:
         //  insert: lea offset+cookie[base], RegTemp
         //  => -cookie[RegTemp, index, shift]
         uint32_t Value =
             llvm::dyn_cast<ConstantInteger32>(MemOperand->getOffset())
                 ->getValue();
-        uint32_t Cookie = Ctx->getRandomizationCookie();
+        uint32_t Cookie = Func->getConstantBlindingCookie();
         Constant *Mask1 = Ctx->getConstantInt(
             MemOperand->getOffset()->getType(), Cookie + Value);
         Constant *Mask2 =
             Ctx->getConstantInt(MemOperand->getOffset()->getType(), 0 - Cookie);
 
         typename Traits::X86OperandMem *TempMemOperand =
             Traits::X86OperandMem::create(Func, MemOperand->getType(),
                                           MemOperand->getBase(), Mask1);
         // If we have already assigned a physical register, we must come from
         // advancedPhiLowering()=>lowerAssign(). In this case we should reuse
@@ skipping 74 matching lines @@
   }
   // the offset is not eligible for blinding or pooling, return the original
   // mem operand
   return MemOperand;
 }
 
 } // end of namespace X86Internal
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICETARGETLOWERINGX86BASEIMPL_H