To ensure that we have more accurate line information for a block

don't elide the branch instruction if it's the only one in the block,
otherwise it's ok.

PR9796 and rdar://11215207

llvm-svn: 154417

1 files changed, 5 insertions, 2 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp b/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp
index 5de66670b2f..0c1ac6982d2 100644
--- a/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp
@@ -821,8 +821,11 @@ FastISel::SelectInstruction(const Instruction *I) {
 /// the CFG.
 void
 FastISel::FastEmitBranch(MachineBasicBlock *MSucc, DebugLoc DL) {
-  if (FuncInfo.MBB->isLayoutSuccessor(MSucc)) {
-    // The unconditional fall-through case, which needs no instructions.
+
+  if (FuncInfo.MBB->getBasicBlock()->size() > 1 && FuncInfo.MBB->isLayoutSuccessor(MSucc)) {
+    // For more accurate line information if this is the only instruction
+    // in the block then emit it, otherwise we have the unconditional
+    // fall-through case, which needs no instructions.
   } else {
     // The unconditional branch case.
     TII.InsertBranch(*FuncInfo.MBB, MSucc, NULL,