Use separate random number generator for each randomization pass

src/IceTargetLoweringX8632.cpp

 //===- subzero/src/IceTargetLoweringX8632.cpp - x86-32 lowering -----------===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
@@ skipping 713 matching lines @@
   Type Ty = T::Ty;
   SizeT Align = typeAlignInBytes(Ty);
   ConstantList Pool = Ctx->getConstantPool(Ty);
 
   Str << "\t.section\t.rodata.cst" << Align << ",\"aM\",@progbits," << Align
       << "\n";
   Str << "\t.align\t" << Align << "\n";
 
   // If reorder-pooled-constants option is set to true, we need to shuffle the
   // constant pool before emitting it.
-  if (Ctx->getFlags().shouldReorderPooledConstants())
-    RandomShuffle(Pool.begin(), Pool.end(), [Ctx](uint64_t N) {
-      return (uint32_t)Ctx->getRNG().next(N);
-    });
+  if (Ctx->getFlags().shouldReorderPooledConstants() && !Pool.empty()) {
+    // Use the constant's kind value as the salt for creating random number
+    // generator.
+    Operand::OperandKind K = (*Pool.begin())->getKind();
+
+    RandomNumberGenerator RNG(Ctx->getFlags().getRandomSeed(),
+                              RPE_PooledConstantReordering, K);
+    RandomShuffle(Pool.begin(), Pool.end(),
+                  [&RNG](uint64_t N) { return (uint32_t)RNG.next(N); });
+  }
 
   for (Constant *C : Pool) {
     if (!C->getShouldBePooled())
       continue;
     typename T::IceType *Const = llvm::cast<typename T::IceType>(C);
     typename T::IceType::PrimType Value = Const->getValue();
     // Use memcpy() to copy bits from Value into RawValue in a way
     // that avoids breaking strict-aliasing rules.
     typename T::PrimitiveIntType RawValue;
     memcpy(&RawValue, &Value, sizeof(Value));
@@ skipping 194 matching lines @@
 // entries in case the high-level table has extra entries.
 #define X(tag, sizeLog2, align, elts, elty, str)                               \
   static_assert(_table1_##tag == _table2_##tag,                                \
                 "Inconsistency between ICETYPEX8632_TABLE and ICETYPE_TABLE");
 ICETYPE_TABLE
 #undef X
 } // end of namespace dummy3
 } // end of anonymous namespace
 
 } // end of namespace Ice