[C++11] Add predecessors(BasicBlock *) / successors(BasicBlock *) iterator ranges.

Summary: This patch introduces two new iterator ranges and updates existing code to use it.  No functional change intended.

Test Plan: All tests (make check-all) still pass.

Reviewers: dblaikie

Reviewed By: dblaikie

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D4481

llvm-svn: 213474
diff --git a/llvm/lib/Transforms/Scalar/LoopUnswitch.cpp b/llvm/lib/Transforms/Scalar/LoopUnswitch.cpp
index 977c53a..68bd4b8 100644
--- a/llvm/lib/Transforms/Scalar/LoopUnswitch.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopUnswitch.cpp
@@ -515,9 +515,9 @@
   }
 
   // Otherwise, this is an unvisited intra-loop node.  Check all successors.
-  for (succ_iterator SI = succ_begin(BB), E = succ_end(BB); SI != E; ++SI) {
+  for (BasicBlock *Succ : successors(BB)) {
     // Check to see if the successor is a trivial loop exit.
-    if (!isTrivialLoopExitBlockHelper(L, *SI, ExitBB, Visited))
+    if (!isTrivialLoopExitBlockHelper(L, Succ, ExitBB, Visited))
       return false;
   }
 
@@ -861,9 +861,7 @@
       PHINode *PN = PHINode::Create(LPad->getType(), 0, "",
                                     ExitSucc->getFirstInsertionPt());
 
-      for (pred_iterator I = pred_begin(ExitSucc), E = pred_end(ExitSucc);
-           I != E; ++I) {
-        BasicBlock *BB = *I;
+      for (BasicBlock *BB : predecessors(ExitSucc)) {
         LandingPadInst *LPI = BB->getLandingPadInst();
         LPI->replaceAllUsesWith(PN);
         PN->addIncoming(LPI, BB);