[llvm] [MachinePipeliner] Add an abstract layer to manipulate Data Dependenc… (PR #109918)

[Ryotaro Kasuga via llvm-commits]

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@@ -3797,3 +3796,71 @@ void ResourceManager::init(int II) {
   NumScheduledMops.clear();
   NumScheduledMops.resize(II);
 }
+
+bool SwingSchedulerDDGEdge::ignoreDependence(bool IgnoreAnti) const {
+  if (Pred.isArtificial() || Dst->isBoundaryNode())
+    return true;
+  // Currently, dependence that is an anti-dependences but not a loop-carried is
+  // also ignored. This behavior is preserved to prevent regression.
+  // FIXME: Remove if this doesn't have significant impact on performance
+  return IgnoreAnti && (Pred.getKind() == SDep::Kind::Anti || Distance != 0);
+}
+
+SwingSchedulerDDG::SwingSchedulerDDGEdges &
+SwingSchedulerDDG::getEdges(const SUnit *SU) {
+  if (SU == EntrySU)
+    return EntrySUEdges;
+  if (SU == ExitSU)
+    return ExitSUEdges;
+  return EdgesVec[SU->NodeNum];
+}
+
+const SwingSchedulerDDG::SwingSchedulerDDGEdges &
+SwingSchedulerDDG::getEdges(const SUnit *SU) const {
+  if (SU == EntrySU)
+    return EntrySUEdges;
+  if (SU == ExitSU)
+    return ExitSUEdges;
+  return EdgesVec[SU->NodeNum];
+}
+
+void SwingSchedulerDDG::addEdge(SUnit *SU, const SwingSchedulerDDGEdge &Edge) {
+  auto &Edges = getEdges(SU);
+  if (Edge.getSrc() == SU)
+    Edges.Succs.push_back(Edge);
+  else
+    Edges.Preds.push_back(Edge);
+}
+
+void SwingSchedulerDDG::initEdges(SUnit *SU) {
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kasuga-fj wrote:

I think we cannot specify `const` here because `SDep::setSUnit` requires a non-const pointer type which is invoked inside the ctor of `SwingSchedulerDDGEdge`.

https://github.com/llvm/llvm-project/pull/109918