MIsched: Added biasCriticalPath.
Allow schedulers to order DAG edges by critical path. This makes
DFS-based heuristics more stable and effective.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@173317 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/ScheduleDAG.cpp b/lib/CodeGen/ScheduleDAG.cpp
index e639c55..70ad949 100644
--- a/lib/CodeGen/ScheduleDAG.cpp
+++ b/lib/CodeGen/ScheduleDAG.cpp
@@ -301,6 +301,21 @@
} while (!WorkList.empty());
}
+void SUnit::biasCriticalPath() {
+ if (NumPreds < 2)
+ return;
+
+ SUnit::pred_iterator BestI = Preds.begin();
+ unsigned MaxDepth = BestI->getSUnit()->getDepth();
+ for (SUnit::pred_iterator
+ I = llvm::next(BestI), E = Preds.end(); I != E; ++I) {
+ if (I->getKind() == SDep::Data && I->getSUnit()->getDepth() > MaxDepth)
+ BestI = I;
+ }
+ if (BestI != Preds.begin())
+ std::swap(*Preds.begin(), *BestI);
+}
+
#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
/// SUnit - Scheduling unit. It's an wrapper around either a single SDNode or
/// a group of nodes flagged together.