Use separate random number generator for each randomization pass

src/IceTargetLoweringX86BaseImpl.h

Index: src/IceTargetLoweringX86BaseImpl.h
diff --git a/src/IceTargetLoweringX86BaseImpl.h b/src/IceTargetLoweringX86BaseImpl.h
index e190b5d0f4bf5b41c2114c9288db3cd426c685ed..a764dd9a3c1db7c25ec852a2a523c5c08f88f09e 100644
--- a/src/IceTargetLoweringX86BaseImpl.h
+++ b/src/IceTargetLoweringX86BaseImpl.h
@@ -4132,10 +4132,11 @@ template <class Machine> void TargetX86Base<Machine>::doAddressOptLoad() {
 }
 
 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));
   }
 }
 
@@ -5139,7 +5140,7 @@ Operand *TargetX86Base<Machine>::randomizeOrPoolImmediate(Constant *Immediate,
       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,
@@ -5218,7 +5219,7 @@ TargetX86Base<Machine>::randomizeOrPoolImmediate(
         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 =