Find loop back edges only after empty blocks are eliminated.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@61752 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 3 insertions, 2 deletions

diff --git a/lib/Transforms/Scalar/CodeGenPrepare.cpp b/lib/Transforms/Scalar/CodeGenPrepare.cpp
index ff9d32c..125b076 100644
--- a/lib/Transforms/Scalar/CodeGenPrepare.cpp
+++ b/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;