[llvm] [SampleProf] Templatize longestCommonSequence (NFC) (PR #114633)

[Kazu Hirata via llvm-commits]

================
@@ -194,82 +195,16 @@ LocToLocMap
 SampleProfileMatcher::longestCommonSequence(const AnchorList &AnchorList1,
                                             const AnchorList &AnchorList2,
                                             bool MatchUnusedFunction) {
-  int32_t Size1 = AnchorList1.size(), Size2 = AnchorList2.size(),
-          MaxDepth = Size1 + Size2;
-  auto Index = [&](int32_t I) { return I + MaxDepth; };
-
-  LocToLocMap EqualLocations;
-  if (MaxDepth == 0)
-    return EqualLocations;
-
-  // Backtrack the SES result.
-  auto Backtrack = [&](const std::vector<std::vector<int32_t>> &Trace,
-                       const AnchorList &AnchorList1,
-                       const AnchorList &AnchorList2,
-                       LocToLocMap &EqualLocations) {
-    int32_t X = Size1, Y = Size2;
-    for (int32_t Depth = Trace.size() - 1; X > 0 || Y > 0; Depth--) {
-      const auto &P = Trace[Depth];
-      int32_t K = X - Y;
-      int32_t PrevK = K;
-      if (K == -Depth || (K != Depth && P[Index(K - 1)] < P[Index(K + 1)]))
-        PrevK = K + 1;
-      else
-        PrevK = K - 1;
-
-      int32_t PrevX = P[Index(PrevK)];
-      int32_t PrevY = PrevX - PrevK;
-      while (X > PrevX && Y > PrevY) {
-        X--;
-        Y--;
-        EqualLocations.insert({AnchorList1[X].first, AnchorList2[Y].first});
-      }
-
-      if (Depth == 0)
-        break;
-
-      if (Y == PrevY)
-        X--;
-      else if (X == PrevX)
-        Y--;
-      X = PrevX;
-      Y = PrevY;
-    }
-  };
-
-  // The greedy LCS/SES algorithm.
-
-  // An array contains the endpoints of the furthest reaching D-paths.
-  std::vector<int32_t> V(2 * MaxDepth + 1, -1);
-  V[Index(1)] = 0;
-  // Trace is used to backtrack the SES result.
-  std::vector<std::vector<int32_t>> Trace;
-  for (int32_t Depth = 0; Depth <= MaxDepth; Depth++) {
-    Trace.push_back(V);
-    for (int32_t K = -Depth; K <= Depth; K += 2) {
-      int32_t X = 0, Y = 0;
-      if (K == -Depth || (K != Depth && V[Index(K - 1)] < V[Index(K + 1)]))
-        X = V[Index(K + 1)];
-      else
-        X = V[Index(K - 1)] + 1;
-      Y = X - K;
-      while (X < Size1 && Y < Size2 &&
-             functionMatchesProfile(
-                 AnchorList1[X].second, AnchorList2[Y].second,
-                 !MatchUnusedFunction /* Find matched function only */))
-        X++, Y++;
-
-      V[Index(K)] = X;
-
-      if (X >= Size1 && Y >= Size2) {
-        // Length of an SES is D.
-        Backtrack(Trace, AnchorList1, AnchorList2, EqualLocations);
-        return EqualLocations;
-      }
-    }
-  }
-  // Length of an SES is greater than MaxDepth.
-  return EqualLocations;
+  LocToLocMap MatchedAnchors;
+  llvm::longestCommonSequence<LineLocation, FunctionId>(
+      AnchorList1, AnchorList2,
+      [&](const FunctionId &A, const FunctionId &B) {
+        return functionMatchesProfile(A, B, !MatchUnusedFunction);
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kazutakahirata wrote:

Thank you for spotting this!  Fixed in the latest revision.

https://github.com/llvm/llvm-project/pull/114633