Avoid finding loop back edges when we are not splitting critical edges in
CodeGenPrepare (which is the default behavior).


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122801 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/CodeGenPrepare.cpp b/lib/Transforms/Scalar/CodeGenPrepare.cpp
index f4edcc7..8df0b3c 100644
--- a/lib/Transforms/Scalar/CodeGenPrepare.cpp
+++ b/lib/Transforms/Scalar/CodeGenPrepare.cpp
@@ -119,8 +119,10 @@
   // unconditional branch.
   EverMadeChange |= EliminateMostlyEmptyBlocks(F);
 
-  // Now find loop back edges.
-  findLoopBackEdges(F);
+  // Now find loop back edges, but only if they are being used to decide which
+  // critical edges to split.
+  if (CriticalEdgeSplit)
+    findLoopBackEdges(F);
 
   bool MadeChange = true;
   while (MadeChange) {