Add a bunch of calls to RemoveDeadNode in LegalizeDAG, so legalization doesn't get confused by CSE later on. Fixes PR11318.

Re-commit of r144034, with an extra fix so that RemoveDeadNode doesn't blow up.

llvm-svn: 144055

1 files changed, 6 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 010a740dc7c..b3f94a49451 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -564,6 +564,12 @@ void SelectionDAG::RemoveDeadNodes(SmallVectorImpl<SDNode *> &DeadNodes,
 
 void SelectionDAG::RemoveDeadNode(SDNode *N, DAGUpdateListener *UpdateListener){
   SmallVector<SDNode*, 16> DeadNodes(1, N);
+
+  // Create a dummy node that adds a reference to the root node, preventing
+  // it from being deleted.  (This matters if the root is an operand of the
+  // dead node.)
+  HandleSDNode Dummy(getRoot());
+
   RemoveDeadNodes(DeadNodes, UpdateListener);
 }