Don't transform in another bad case: if the block is empty, it should be

simplified before we do this xform so that our cost model is accurate.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@31864 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/CodeGen/BranchFolding.cpp b/lib/CodeGen/BranchFolding.cpp
index c69930da81ee34ce7d4a7bba0abea7689fd5d9f4..8ded3cdc64d4633245a067f4a699d16f7e1848e3 100644 (file)
--- a/lib/CodeGen/BranchFolding.cpp
+++ b/lib/CodeGen/BranchFolding.cpp
@@ -729,7 +729,8 @@ void BranchFolder::OptimizeBlock(MachineBasicBlock *MBB) {
       //
       // In this case, we could actually be moving the return block *into* a
       // loop!
-      if (DoTransform && !MBB->succ_empty() && !CanFallThrough(PriorTBB))
+      if (DoTransform && !MBB->succ_empty() &&
+          (!CanFallThrough(PriorTBB) || PriorTBB->empty()))
         DoTransform = false;