Use separate random number generator for each randomization pass

src/IceTargetLoweringX8632.cpp

Index: src/IceTargetLoweringX8632.cpp
diff --git a/src/IceTargetLoweringX8632.cpp b/src/IceTargetLoweringX8632.cpp
index 466564d8408bba025e049ef93f2c557d935818c3..8f278b0ecf0907884748ad20cf05c6647e3241bb 100644
--- a/src/IceTargetLoweringX8632.cpp
+++ b/src/IceTargetLoweringX8632.cpp
@@ -731,10 +731,18 @@ void TargetDataX8632::emitConstantPool(GlobalContext *Ctx) {
 
   // 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()) {
+    if (!Pool.empty()) {

[Jim Stichnoth, 2015/08/19 19:03:04]

can probably combine this condition with the above:
  if (shouldReorder && !empty()) { ... }

[qining, 2015/08/19 23:25:49]

Done.

+      // 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(),
+                                RS_PooledConstantReordering, K);
+      RandomShuffle(Pool.begin(), Pool.end(),
+                    [&RNG](uint64_t N) { return (uint32_t)RNG.next(N); });
+    }
+  }
 
   for (Constant *C : Pool) {
     if (!C->getShouldBePooled())