Change all self assignments X=X to (void)X, so that we can turn on a
new gcc warning that complains on self-assignments and
self-initializations.

llvm-svn: 122458
diff --git a/llvm/lib/Transforms/Utils/DemoteRegToStack.cpp b/llvm/lib/Transforms/Utils/DemoteRegToStack.cpp
index 8e82a02..8cc2649 100644
--- a/llvm/lib/Transforms/Utils/DemoteRegToStack.cpp
+++ b/llvm/lib/Transforms/Utils/DemoteRegToStack.cpp
@@ -129,7 +129,7 @@
   for (unsigned i = 0, e = P->getNumIncomingValues(); i < e; ++i) {
     if (InvokeInst *II = dyn_cast<InvokeInst>(P->getIncomingValue(i))) {
       assert(II->getParent() != P->getIncomingBlock(i) &&
-             "Invoke edge not supported yet"); II=II;
+             "Invoke edge not supported yet"); (void)II;
     }
     new StoreInst(P->getIncomingValue(i), Slot,
                   P->getIncomingBlock(i)->getTerminator());