[DAG, X86] Revert r327197 "Revert r327170, r327171, r327172"

Reland ISel cycle checking improvements after simplifying node id
invariant traversal and correcting typo.

llvm-svn: 327898

1 files changed, 9 insertions, 6 deletions

diff --git a/llvm/lib/Target/SystemZ/SystemZISelDAGToDAG.cpp b/llvm/lib/Target/SystemZ/SystemZISelDAGToDAG.cpp
index 9bf2474915c..6e2130828bb 100644
--- a/llvm/lib/Target/SystemZ/SystemZISelDAGToDAG.cpp
+++ b/llvm/lib/Target/SystemZ/SystemZISelDAGToDAG.cpp
@@ -596,7 +596,13 @@ static void insertDAGNode(SelectionDAG *DAG, SDNode *Pos, SDValue N) {
   if (N.getNode()->getNodeId() == -1 ||
       N.getNode()->getNodeId() > Pos->getNodeId()) {
     DAG->RepositionNode(Pos->getIterator(), N.getNode());
-    N.getNode()->setNodeId(Pos->getNodeId());
+    // Mark Node as invalid for pruning as after this it may be a successor to a
+    // selected node but otherwise be in the same position of Pos.
+    // Conservatively mark it with the same -abs(Id) to assure node id
+    // invariant is preserved.
+    int PId = Pos->getNodeId();
+    int InvalidatedPId = -(PId + 1);
+    N->setNodeId((PId > 0) ? InvalidatedPId : PId);
   }
 }
 
@@ -1027,8 +1033,7 @@ bool SystemZDAGToDAGISel::tryRISBGZero(SDNode *N) {
   };
   SDValue New = convertTo(
       DL, VT, SDValue(CurDAG->getMachineNode(Opcode, DL, OpcodeVT, Ops), 0));
-  ReplaceUses(N, New.getNode());
-  CurDAG->RemoveDeadNode(N);
+  ReplaceNode(N, New.getNode());
   return true;
 }
 
@@ -1119,8 +1124,7 @@ void SystemZDAGToDAGISel::splitLargeImmediate(unsigned Opcode, SDNode *Node,
   SDValue Lower = CurDAG->getConstant(LowerVal, DL, VT);
   SDValue Or = CurDAG->getNode(Opcode, DL, VT, Upper, Lower);
 
-  ReplaceUses(Node, Or.getNode());
-  CurDAG->RemoveDeadNode(Node);
+  ReplaceNode(Node, Or.getNode());
 
   SelectCode(Or.getNode());
 }
@@ -1618,4 +1622,3 @@ void SystemZDAGToDAGISel::PreprocessISelDAG() {
   if (MadeChange)
     CurDAG->RemoveDeadNodes();
 }
-