Resurrect the assertion removed by r227717

Summary: MSVC can compile "LoopID->getOperand(0) == LoopID" when LoopID is MDNode*.

Test Plan: no regression

Reviewers: mkuper

Subscribers: jholewinski, llvm-commits

Differential Revision: http://reviews.llvm.org/D7327

llvm-svn: 227853

1 files changed, 4 insertions, 3 deletions

diff --git a/llvm/lib/Transforms/Utils/LoopUnroll.cpp b/llvm/lib/Transforms/Utils/LoopUnroll.cpp
index 0ee2fee41dd..accb7316cab 100644
--- a/llvm/lib/Transforms/Utils/LoopUnroll.cpp
+++ b/llvm/lib/Transforms/Utils/LoopUnroll.cpp
@@ -553,16 +553,17 @@ bool llvm::UnrollLoop(Loop *L, unsigned Count, unsigned TripCount,
 /// Given an llvm.loop loop id metadata node, returns the loop hint metadata
 /// node with the given name (for example, "llvm.loop.unroll.count"). If no
 /// such metadata node exists, then nullptr is returned.
-const MDNode *llvm::GetUnrollMetadata(const MDNode *LoopID, StringRef Name) {
+MDNode *llvm::GetUnrollMetadata(MDNode *LoopID, StringRef Name) {
   // First operand should refer to the loop id itself.
   assert(LoopID->getNumOperands() > 0 && "requires at least one operand");
+  assert(LoopID->getOperand(0) == LoopID && "invalid loop id");
 
   for (unsigned i = 1, e = LoopID->getNumOperands(); i < e; ++i) {
-    const MDNode *MD = dyn_cast<MDNode>(LoopID->getOperand(i));
+    MDNode *MD = dyn_cast<MDNode>(LoopID->getOperand(i));
     if (!MD)
       continue;
 
-    const MDString *S = dyn_cast<MDString>(MD->getOperand(0));
+    MDString *S = dyn_cast<MDString>(MD->getOperand(0));
     if (!S)
       continue;