Modify df_iterator to support post-order actions

Summary: This makes a change to the state used to maintain visited information for depth first iterator. We know assume a method "completed(...)" which is called after all children of a node have been visited. In all existing cases, this method does nothing so this patch has no functional changes.  It will however allow a client to distinguish back from cross edges in a DFS tree.

Reviewers: nadav, mehdi_amini, dberlin

Subscribers: MatzeB, mzolotukhin, twoh, freik, llvm-commits

Differential Revision: https://reviews.llvm.org/D25191

llvm-svn: 283391

1 files changed, 1 insertions, 1 deletions

diff --git a/llvm/lib/CodeGen/PrologEpilogInserter.cpp b/llvm/lib/CodeGen/PrologEpilogInserter.cpp
index 6ddf9537a71..8013c115726 100644
--- a/llvm/lib/CodeGen/PrologEpilogInserter.cpp
+++ b/llvm/lib/CodeGen/PrologEpilogInserter.cpp
@@ -1008,7 +1008,7 @@ void PEI::replaceFrameIndices(MachineFunction &Fn) {
   // Store SPAdj at exit of a basic block.
   SmallVector<int, 8> SPState;
   SPState.resize(Fn.getNumBlockIDs());
-  SmallPtrSet<MachineBasicBlock*, 8> Reachable;
+  df_iterator_default_set<MachineBasicBlock*> Reachable;
 
   // Iterate over the reachable blocks in DFS order.
   for (auto DFI = df_ext_begin(&Fn, Reachable), DFE = df_ext_end(&Fn, Reachable);