[DebugInfo][LCSSA] Preserve debug location in lcssa phis

Summary:
When inserting lcssa Phi Nodes in the exit block
mak sure to preserve the original instructions DL.

Reviewers: vsk

Subscribers: JDevlieghere, llvm-commits

Differential Revision: https://reviews.llvm.org/D50009

llvm-svn: 338391
diff --git a/llvm/lib/Transforms/Utils/LCSSA.cpp b/llvm/lib/Transforms/Utils/LCSSA.cpp
index 31834af..a1f8e74 100644
--- a/llvm/lib/Transforms/Utils/LCSSA.cpp
+++ b/llvm/lib/Transforms/Utils/LCSSA.cpp
@@ -144,7 +144,8 @@
 
       PHINode *PN = PHINode::Create(I->getType(), PredCache.size(ExitBB),
                                     I->getName() + ".lcssa", &ExitBB->front());
-
+      // Get the debug location from the original instruction.
+      PN->setDebugLoc(I->getDebugLoc());
       // Add inputs from inside the loop for this PHI.
       for (BasicBlock *Pred : PredCache.get(ExitBB)) {
         PN->addIncoming(I, Pred);