Find loop back edges only after empty blocks are eliminated.

llvm-svn: 61752

1 files changed, 3 insertions, 2 deletions

diff --git a/llvm/lib/Transforms/Scalar/CodeGenPrepare.cpp b/llvm/lib/Transforms/Scalar/CodeGenPrepare.cpp
index ff9d32c316d..125b0760954 100644
--- a/llvm/lib/Transforms/Scalar/CodeGenPrepare.cpp
+++ b/llvm/lib/Transforms/Scalar/CodeGenPrepare.cpp
@@ -125,12 +125,13 @@ void CodeGenPrepare::findLoopBackEdges(Function &F) {
 bool CodeGenPrepare::runOnFunction(Function &F) {
   bool EverMadeChange = false;
 
-  findLoopBackEdges(F);
-
   // First pass, eliminate blocks that contain only PHI nodes and an
   // unconditional branch.
   EverMadeChange |= EliminateMostlyEmptyBlocks(F);
 
+  // Now find loop back edges.
+  findLoopBackEdges(F);
+
   bool MadeChange = true;
   while (MadeChange) {
     MadeChange = false;