[PATCH] D33769: [SelectionDAG] Get rid of recursion in CalcNodeSethiUllmanNumber

[Philip Reames via Phabricator via llvm-commits]

reames added a comment.

Argument accepted, minor comment below.



================
Comment at: lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp:1864
 CalcNodeSethiUllmanNumber(const SUnit *SU, std::vector<unsigned> &SUNumbers) {
-  unsigned &SethiUllmanNumber = SUNumbers[SU->NodeNum];
-  if (SethiUllmanNumber != 0)
-    return SethiUllmanNumber;
-
-  unsigned Extra = 0;
-  for (const SDep &Pred : SU->Preds) {
-    if (Pred.isCtrl()) continue;  // ignore chain preds
-    SUnit *PredSU = Pred.getSUnit();
-    unsigned PredSethiUllman = CalcNodeSethiUllmanNumber(PredSU, SUNumbers);
-    if (PredSethiUllman > SethiUllmanNumber) {
-      SethiUllmanNumber = PredSethiUllman;
-      Extra = 0;
-    } else if (PredSethiUllman == SethiUllmanNumber)
-      ++Extra;
-  }
+  if (SUNumbers[SU->NodeNum] == 0) {
+    // Use WorkList to avoid stack overflow on excessively large IRs.
----------------
Reduce nesting by inverting conditional or using impl helper pattern.


https://reviews.llvm.org/D33769