1 files changed, 13 insertions, 3 deletions

diff --git a/lib/Transforms/Utils/LoopUnroll.cpp b/lib/Transforms/Utils/LoopUnroll.cpp
index d68427afce79..6232f3286ffd 100644
--- a/lib/Transforms/Utils/LoopUnroll.cpp
+++ b/lib/Transforms/Utils/LoopUnroll.cpp
@@ -108,8 +108,19 @@ static BasicBlock *FoldBlockIntoPredecessor(BasicBlock *BB, LoopInfo* LI) {
 bool llvm::UnrollLoop(Loop *L, unsigned Count, LoopInfo* LI, LPPassManager* LPM) {
   assert(L->isLCSSAForm());
 
-  BasicBlock *Header = L->getHeader();
+  BasicBlock *Preheader = L->getLoopPreheader();
+  if (!Preheader) {
+    DEBUG(errs() << "  Can't unroll; loop preheader-insertion failed.\n");
+    return false;
+  }
+
   BasicBlock *LatchBlock = L->getLoopLatch();
+  if (!LatchBlock) {
+    DEBUG(errs() << "  Can't unroll; loop exit-block-insertion failed.\n");
+    return false;
+  }
+
+  BasicBlock *Header = L->getHeader();
   BranchInst *BI = dyn_cast<BranchInst>(LatchBlock->getTerminator());
   
   if (!BI || BI->isUnconditional()) {
@@ -351,8 +362,7 @@ bool llvm::UnrollLoop(Loop *L, unsigned Count, LoopInfo* LI, LPPassManager* LPM)
 
       if (isInstructionTriviallyDead(Inst))
         (*BB)->getInstList().erase(Inst);
-      else if (Constant *C = ConstantFoldInstruction(Inst, 
-                                                     Header->getContext())) {
+      else if (Constant *C = ConstantFoldInstruction(Inst)) {
         Inst->replaceAllUsesWith(C);
         (*BB)->getInstList().erase(Inst);
       }