Set proper debug location for branch added in BasicBlock::splitBasicBlock().

This improves debug locations in passes that do a lot of basic block
transformations. Important case is LoopUnroll pass, the test for correct
debug locations accompanies this change.

Test Plan: regression test suite

Reviewers: dblaikie, sanjoy

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D10367

llvm-svn: 239551

1 files changed, 4 insertions, 1 deletions

diff --git a/llvm/lib/IR/BasicBlock.cpp b/llvm/lib/IR/BasicBlock.cpp
index 70ae3c3..77cb10d 100644
--- a/llvm/lib/IR/BasicBlock.cpp
+++ b/llvm/lib/IR/BasicBlock.cpp
@@ -362,12 +362,15 @@ BasicBlock *BasicBlock::splitBasicBlock(iterator I, const Twine &BBName) {
   BasicBlock *New = BasicBlock::Create(getContext(), BBName,
                                        getParent(), InsertBefore);
 
+  // Save DebugLoc of split point before invalidating iterator.
+  DebugLoc Loc = I->getDebugLoc();
   // Move all of the specified instructions from the original basic block into
   // the new basic block.
   New->getInstList().splice(New->end(), this->getInstList(), I, end());
 
   // Add a branch instruction to the newly formed basic block.
-  BranchInst::Create(New, this);
+  BranchInst *BI = BranchInst::Create(New, this);
+  BI->setDebugLoc(Loc);
 
   // Now we must loop through all of the successors of the New block (which
   // _were_ the successors of the 'this' block), and update any PHI nodes in