ISelDAG: spot chain cycles involving MachineNodes
Previously, the DAGISel function WalkChainUsers was spotting that it
had entered already-selected territory by whether a node was a
MachineNode (amongst other things). Since it's fairly common practice
to insert MachineNodes during ISelLowering, this was not the correct
check.
Looking around, it seems that other nodes get their NodeId set to -1
upon selection, so this makes sure the same thing happens to all
MachineNodes and uses that characteristic to determine whether we
should stop looking for a loop during selection.
This should fix PR15840.
llvm-svn: 191165
diff --git a/llvm/lib/Target/ARM/ARMISelDAGToDAG.cpp b/llvm/lib/Target/ARM/ARMISelDAGToDAG.cpp
index c2dbcb9..f6b3827 100644
--- a/llvm/lib/Target/ARM/ARMISelDAGToDAG.cpp
+++ b/llvm/lib/Target/ARM/ARMISelDAGToDAG.cpp
@@ -2383,8 +2383,10 @@
SDNode *ARMDAGToDAGISel::Select(SDNode *N) {
SDLoc dl(N);
- if (N->isMachineOpcode())
+ if (N->isMachineOpcode()) {
+ N->setNodeId(-1);
return NULL; // Already selected.
+ }
switch (N->getOpcode()) {
default: break;