When unfolding a load during scheduling, the new operator node has
a data dependency on the load node, so it really needs a
data-dependence edge to the load node, even if the load previously
existed.
And add a few comments.
llvm-svn: 67554
diff --git a/llvm/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp b/llvm/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp
index 8e44997..705e4de 100644
--- a/llvm/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp
@@ -410,6 +410,7 @@
NewSU->isCommutable = true;
ComputeLatency(NewSU);
+ // Record all the edges to and from the old SU, by category.
SmallVector<SDep, 4> ChainPreds;
SmallVector<SDep, 4> ChainSuccs;
SmallVector<SDep, 4> LoadPreds;
@@ -433,6 +434,7 @@
NodeSuccs.push_back(*I);
}
+ // Now assign edges to the newly-created nodes.
for (unsigned i = 0, e = ChainPreds.size(); i != e; ++i) {
const SDep &Pred = ChainPreds[i];
RemovePred(SU, Pred);
@@ -468,9 +470,10 @@
AddPred(SuccDep, D);
}
}
- if (isNewLoad) {
- AddPred(NewSU, SDep(LoadSU, SDep::Order, LoadSU->Latency));
- }
+
+ // Add a data dependency to reflect that NewSU reads the value defined
+ // by LoadSU.
+ AddPred(NewSU, SDep(LoadSU, SDep::Data, LoadSU->Latency));
if (isNewLoad)
AvailableQueue->addNode(LoadSU);