[PATCH] D64359: [LOOPINFO] Add member function to retrieve loops in breadth-first order

[Ettore Tiotto via Phabricator via llvm-commits]

etiotto created this revision.
etiotto added reviewers: Whitney, Meinersbur.
Herald added a project: LLVM.
Herald added a subscriber: llvm-commits.
etiotto added reviewers: fhahn, hfinkel.

LoopInfo contains a utility to retrieve loops in depth-first order (preorder traversal). This patch adds a similar utility to retrieve loops in breadth-first order.


Repository:
  rL LLVM

https://reviews.llvm.org/D64359

Files:
  llvm/include/llvm/Analysis/LoopInfo.h


Index: llvm/include/llvm/Analysis/LoopInfo.h
===================================================================
--- llvm/include/llvm/Analysis/LoopInfo.h
+++ llvm/include/llvm/Analysis/LoopInfo.h
@@ -346,6 +346,43 @@
     return PreOrderLoops;
   }
 
+  /// Return all inner loops in the loop nest rooted by the loop in
+  /// breadth-first order.
+  template <class Type>
+  static void
+  getInnerLoopsInBreadthFirstOrder(const LoopT &L,
+                                   SmallVectorImpl<Type> &BreadthFirstLoops) {
+    SmallVector<LoopT *, 4> BreadthFirstWorklist;
+    BreadthFirstWorklist.push_back(const_cast<LoopT *>(&L));
+
+    while (!BreadthFirstWorklist.empty()) {
+      LoopT *L = BreadthFirstWorklist.pop_back_val();
+      const auto &SubLoops = L->getSubLoops();
+      if (!SubLoops.empty()) {
+        BreadthFirstWorklist.insert(BreadthFirstWorklist.begin(),
+                                    SubLoops.rbegin(), SubLoops.rend());
+        BreadthFirstLoops.append(SubLoops.begin(), SubLoops.end());
+      }
+    }
+  }
+
+  /// Return all loops in the loop nest rooted by the loop in breadth-first
+  /// order.
+  SmallVector<const LoopT *, 4> getLoopsInBreadthFirstOrder() const {
+    SmallVector<const LoopT *, 4> BreadthFirstLoops;
+    const LoopT *CurLoop = static_cast<const LoopT *>(this);
+    BreadthFirstLoops.push_back(CurLoop);
+    getInnerLoopsInBreadthFirstOrder(*CurLoop, BreadthFirstLoops);
+    return BreadthFirstLoops;
+  }
+  SmallVector<LoopT *, 4> getLoopsInBreadthFirstOrder() {
+    SmallVector<LoopT *, 4> BreadthFirstLoops;
+    LoopT *CurLoop = static_cast<LoopT *>(this);
+    BreadthFirstLoops.push_back(CurLoop);
+    getInnerLoopsInBreadthFirstOrder(*CurLoop, BreadthFirstLoops);
+    return BreadthFirstLoops;
+  }
+
   //===--------------------------------------------------------------------===//
   // APIs for updating loop information after changing the CFG
   //


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