[llvm-branch-commits] [llvm] 5b2feee - Revert "[CodeGen] Introduce `MachineDomTreeUpdater` (#95369)"

via llvm-branch-commits llvm-branch-commits at lists.llvm.org
Wed Jun 26 21:30:52 PDT 2024


Author: paperchalice
Date: 2024-06-27T12:30:50+08:00
New Revision: 5b2feeef6364981528c1cf083bf8d952f7104b02

URL: https://github.com/llvm/llvm-project/commit/5b2feeef6364981528c1cf083bf8d952f7104b02
DIFF: https://github.com/llvm/llvm-project/commit/5b2feeef6364981528c1cf083bf8d952f7104b02.diff

LOG: Revert "[CodeGen] Introduce `MachineDomTreeUpdater` (#95369)"

This reverts commit 6ca387cbcb207abe2a07bbb1b536f099c2e246e7.

Added: 
    

Modified: 
    llvm/include/llvm/Analysis/DomTreeUpdater.h
    llvm/include/llvm/CodeGen/MachineBasicBlock.h
    llvm/include/llvm/CodeGen/MachinePostDominators.h
    llvm/lib/Analysis/DomTreeUpdater.cpp
    llvm/lib/CodeGen/CMakeLists.txt
    llvm/lib/CodeGen/MachineBasicBlock.cpp
    llvm/unittests/CodeGen/CMakeLists.txt

Removed: 
    llvm/include/llvm/Analysis/GenericDomTreeUpdater.h
    llvm/include/llvm/CodeGen/MachineDomTreeUpdater.h
    llvm/lib/CodeGen/MachineDomTreeUpdater.cpp
    llvm/unittests/CodeGen/MachineDomTreeUpdaterTest.cpp


################################################################################
diff  --git a/llvm/include/llvm/Analysis/DomTreeUpdater.h b/llvm/include/llvm/Analysis/DomTreeUpdater.h
index 2b838a311440e..ddb958455ccd7 100644
--- a/llvm/include/llvm/Analysis/DomTreeUpdater.h
+++ b/llvm/include/llvm/Analysis/DomTreeUpdater.h
@@ -15,8 +15,6 @@
 #define LLVM_ANALYSIS_DOMTREEUPDATER_H
 
 #include "llvm/ADT/SmallPtrSet.h"
-#include "llvm/Analysis/GenericDomTreeUpdater.h"
-#include "llvm/Analysis/PostDominators.h"
 #include "llvm/IR/Dominators.h"
 #include "llvm/IR/ValueHandle.h"
 #include "llvm/Support/Compiler.h"
@@ -25,17 +23,66 @@
 #include <vector>
 
 namespace llvm {
+class PostDominatorTree;
 
-class DomTreeUpdater
-    : public GenericDomTreeUpdater<DomTreeUpdater, DominatorTree,
-                                   PostDominatorTree> {
-  friend GenericDomTreeUpdater<DomTreeUpdater, DominatorTree,
-                               PostDominatorTree>;
-
+class DomTreeUpdater {
 public:
-  using Base =
-      GenericDomTreeUpdater<DomTreeUpdater, DominatorTree, PostDominatorTree>;
-  using Base::Base;
+  enum class UpdateStrategy : unsigned char { Eager = 0, Lazy = 1 };
+
+  explicit DomTreeUpdater(UpdateStrategy Strategy_) : Strategy(Strategy_) {}
+  DomTreeUpdater(DominatorTree &DT_, UpdateStrategy Strategy_)
+      : DT(&DT_), Strategy(Strategy_) {}
+  DomTreeUpdater(DominatorTree *DT_, UpdateStrategy Strategy_)
+      : DT(DT_), Strategy(Strategy_) {}
+  DomTreeUpdater(PostDominatorTree &PDT_, UpdateStrategy Strategy_)
+      : PDT(&PDT_), Strategy(Strategy_) {}
+  DomTreeUpdater(PostDominatorTree *PDT_, UpdateStrategy Strategy_)
+      : PDT(PDT_), Strategy(Strategy_) {}
+  DomTreeUpdater(DominatorTree &DT_, PostDominatorTree &PDT_,
+                 UpdateStrategy Strategy_)
+      : DT(&DT_), PDT(&PDT_), Strategy(Strategy_) {}
+  DomTreeUpdater(DominatorTree *DT_, PostDominatorTree *PDT_,
+                 UpdateStrategy Strategy_)
+      : DT(DT_), PDT(PDT_), Strategy(Strategy_) {}
+
+  ~DomTreeUpdater() { flush(); }
+
+  /// Returns true if the current strategy is Lazy.
+  bool isLazy() const { return Strategy == UpdateStrategy::Lazy; };
+
+  /// Returns true if the current strategy is Eager.
+  bool isEager() const { return Strategy == UpdateStrategy::Eager; };
+
+  /// Returns true if it holds a DominatorTree.
+  bool hasDomTree() const { return DT != nullptr; }
+
+  /// Returns true if it holds a PostDominatorTree.
+  bool hasPostDomTree() const { return PDT != nullptr; }
+
+  /// Returns true if there is BasicBlock awaiting deletion.
+  /// The deletion will only happen until a flush event and
+  /// all available trees are up-to-date.
+  /// Returns false under Eager UpdateStrategy.
+  bool hasPendingDeletedBB() const { return !DeletedBBs.empty(); }
+
+  /// Returns true if DelBB is awaiting deletion.
+  /// Returns false under Eager UpdateStrategy.
+  bool isBBPendingDeletion(BasicBlock *DelBB) const;
+
+  /// Returns true if either of DT or PDT is valid and the tree has at
+  /// least one update pending. If DT or PDT is nullptr it is treated
+  /// as having no pending updates. This function does not check
+  /// whether there is BasicBlock awaiting deletion.
+  /// Returns false under Eager UpdateStrategy.
+  bool hasPendingUpdates() const;
+
+  /// Returns true if there are DominatorTree updates queued.
+  /// Returns false under Eager UpdateStrategy or DT is nullptr.
+  bool hasPendingDomTreeUpdates() const;
+
+  /// Returns true if there are PostDominatorTree updates queued.
+  /// Returns false under Eager UpdateStrategy or PDT is nullptr.
+  bool hasPendingPostDomTreeUpdates() const;
 
   ///@{
   /// \name Mutation APIs
@@ -58,6 +105,51 @@ class DomTreeUpdater
   /// Although GenericDomTree provides several update primitives,
   /// it is not encouraged to use these APIs directly.
 
+  /// Submit updates to all available trees.
+  /// The Eager Strategy flushes updates immediately while the Lazy Strategy
+  /// queues the updates.
+  ///
+  /// Note: The "existence" of an edge in a CFG refers to the CFG which DTU is
+  /// in sync with + all updates before that single update.
+  ///
+  /// CAUTION!
+  /// 1. It is required for the state of the LLVM IR to be updated
+  /// *before* submitting the updates because the internal update routine will
+  /// analyze the current state of the CFG to determine whether an update
+  /// is valid.
+  /// 2. It is illegal to submit any update that has already been submitted,
+  /// i.e., you are supposed not to insert an existent edge or delete a
+  /// nonexistent edge.
+  void applyUpdates(ArrayRef<DominatorTree::UpdateType> Updates);
+
+  /// Submit updates to all available trees. It will also
+  /// 1. discard duplicated updates,
+  /// 2. remove invalid updates. (Invalid updates means deletion of an edge that
+  /// still exists or insertion of an edge that does not exist.)
+  /// The Eager Strategy flushes updates immediately while the Lazy Strategy
+  /// queues the updates.
+  ///
+  /// Note: The "existence" of an edge in a CFG refers to the CFG which DTU is
+  /// in sync with + all updates before that single update.
+  ///
+  /// CAUTION!
+  /// 1. It is required for the state of the LLVM IR to be updated
+  /// *before* submitting the updates because the internal update routine will
+  /// analyze the current state of the CFG to determine whether an update
+  /// is valid.
+  /// 2. It is illegal to submit any update that has already been submitted,
+  /// i.e., you are supposed not to insert an existent edge or delete a
+  /// nonexistent edge.
+  /// 3. It is only legal to submit updates to an edge in the order CFG changes
+  /// are made. The order you submit updates on 
diff erent edges is not
+  /// restricted.
+  void applyUpdatesPermissive(ArrayRef<DominatorTree::UpdateType> Updates);
+
+  /// Notify DTU that the entry block was replaced.
+  /// Recalculate all available trees and flush all BasicBlocks
+  /// awaiting deletion immediately.
+  void recalculate(Function &F);
+
   /// Delete DelBB. DelBB will be removed from its Parent and
   /// erased from available trees if it exists and finally get deleted.
   /// Under Eager UpdateStrategy, DelBB will be processed immediately.
@@ -80,6 +172,33 @@ class DomTreeUpdater
 
   ///@}
 
+  ///@{
+  /// \name Flush APIs
+  ///
+  /// CAUTION! By the moment these flush APIs are called, the current CFG needs
+  /// to be the same as the CFG which DTU is in sync with + all updates
+  /// submitted.
+
+  /// Flush DomTree updates and return DomTree.
+  /// It flushes Deleted BBs if both trees are up-to-date.
+  /// It must only be called when it has a DomTree.
+  DominatorTree &getDomTree();
+
+  /// Flush PostDomTree updates and return PostDomTree.
+  /// It flushes Deleted BBs if both trees are up-to-date.
+  /// It must only be called when it has a PostDomTree.
+  PostDominatorTree &getPostDomTree();
+
+  /// Apply all pending updates to available trees and flush all BasicBlocks
+  /// awaiting deletion.
+
+  void flush();
+
+  ///@}
+
+  /// Debug method to help view the internal state of this class.
+  LLVM_DUMP_METHOD void dump() const;
+
 private:
   class CallBackOnDeletion final : public CallbackVH {
   public:
@@ -97,7 +216,16 @@ class DomTreeUpdater
     }
   };
 
+  SmallVector<DominatorTree::UpdateType, 16> PendUpdates;
+  size_t PendDTUpdateIndex = 0;
+  size_t PendPDTUpdateIndex = 0;
+  DominatorTree *DT = nullptr;
+  PostDominatorTree *PDT = nullptr;
+  const UpdateStrategy Strategy;
+  SmallPtrSet<BasicBlock *, 8> DeletedBBs;
   std::vector<CallBackOnDeletion> Callbacks;
+  bool IsRecalculatingDomTree = false;
+  bool IsRecalculatingPostDomTree = false;
 
   /// First remove all the instructions of DelBB and then make sure DelBB has a
   /// valid terminator instruction which is necessary to have when DelBB still
@@ -109,28 +237,32 @@ class DomTreeUpdater
   /// Returns true if at least one BasicBlock is deleted.
   bool forceFlushDeletedBB();
 
-  /// Debug method to help view the internal state of this class.
-  LLVM_DUMP_METHOD void dump() const {
-    Base::dump();
-#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
-    raw_ostream &OS = dbgs();
-    OS << "Pending Callbacks:\n";
-    int Index = 0;
-    for (const auto &BB : Callbacks) {
-      OS << "  " << Index << " : ";
-      ++Index;
-      if (BB->hasName())
-        OS << BB->getName() << "(";
-      else
-        OS << "(no_name)(";
-      OS << BB << ")\n";
-    }
-#endif
-  }
-};
+  /// Helper function to apply all pending DomTree updates.
+  void applyDomTreeUpdates();
+
+  /// Helper function to apply all pending PostDomTree updates.
+  void applyPostDomTreeUpdates();
+
+  /// Helper function to flush deleted BasicBlocks if all available
+  /// trees are up-to-date.
+  void tryFlushDeletedBB();
 
-extern template class GenericDomTreeUpdater<DomTreeUpdater, DominatorTree,
-                                            PostDominatorTree>;
+  /// Drop all updates applied by all available trees and delete BasicBlocks if
+  /// all available trees are up-to-date.
+  void dropOutOfDateUpdates();
+
+  /// Erase Basic Block node that has been unlinked from Function
+  /// in the DomTree and PostDomTree.
+  void eraseDelBBNode(BasicBlock *DelBB);
+
+  /// Returns true if the update appears in the LLVM IR.
+  /// It is used to check whether an update is valid in
+  /// insertEdge/deleteEdge or is unnecessary in the batch update.
+  bool isUpdateValid(DominatorTree::UpdateType Update) const;
+
+  /// Returns true if the update is self dominance.
+  bool isSelfDominance(DominatorTree::UpdateType Update) const;
+};
 } // namespace llvm
 
 #endif // LLVM_ANALYSIS_DOMTREEUPDATER_H

diff  --git a/llvm/include/llvm/Analysis/GenericDomTreeUpdater.h b/llvm/include/llvm/Analysis/GenericDomTreeUpdater.h
deleted file mode 100644
index 7092c67083a67..0000000000000
--- a/llvm/include/llvm/Analysis/GenericDomTreeUpdater.h
+++ /dev/null
@@ -1,525 +0,0 @@
-//===- GenericDomTreeUpdater.h ----------------------------------*- C++ -*-===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-//
-// This file defines the GenericDomTreeUpdater class, which provides a uniform
-// way to update dominator tree related data structures.
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef LLVM_ANALYSIS_GENERICDOMTREEUPDATER_H
-#define LLVM_ANALYSIS_GENERICDOMTREEUPDATER_H
-
-#include "llvm/ADT/ArrayRef.h"
-#include "llvm/ADT/SmallSet.h"
-#include "llvm/Support/Debug.h"
-#include "llvm/Support/raw_ostream.h"
-
-namespace llvm {
-
-template <typename DerivedT, typename DomTreeT, typename PostDomTreeT>
-class GenericDomTreeUpdater {
-  DerivedT &derived() { return *static_cast<DerivedT *>(this); }
-  const DerivedT &derived() const {
-    return *static_cast<const DerivedT *>(this);
-  }
-
-public:
-  enum class UpdateStrategy : unsigned char { Eager = 0, Lazy = 1 };
-  using BasicBlockT = typename DomTreeT::NodeType;
-
-  explicit GenericDomTreeUpdater(UpdateStrategy Strategy_)
-      : Strategy(Strategy_) {}
-  GenericDomTreeUpdater(DomTreeT &DT_, UpdateStrategy Strategy_)
-      : DT(&DT_), Strategy(Strategy_) {}
-  GenericDomTreeUpdater(DomTreeT *DT_, UpdateStrategy Strategy_)
-      : DT(DT_), Strategy(Strategy_) {}
-  GenericDomTreeUpdater(PostDomTreeT &PDT_, UpdateStrategy Strategy_)
-      : PDT(&PDT_), Strategy(Strategy_) {}
-  GenericDomTreeUpdater(PostDomTreeT *PDT_, UpdateStrategy Strategy_)
-      : PDT(PDT_), Strategy(Strategy_) {}
-  GenericDomTreeUpdater(DomTreeT &DT_, PostDomTreeT &PDT_,
-                        UpdateStrategy Strategy_)
-      : DT(&DT_), PDT(&PDT_), Strategy(Strategy_) {}
-  GenericDomTreeUpdater(DomTreeT *DT_, PostDomTreeT *PDT_,
-                        UpdateStrategy Strategy_)
-      : DT(DT_), PDT(PDT_), Strategy(Strategy_) {}
-
-  ~GenericDomTreeUpdater() { flush(); }
-
-  /// Returns true if the current strategy is Lazy.
-  bool isLazy() const { return Strategy == UpdateStrategy::Lazy; };
-
-  /// Returns true if the current strategy is Eager.
-  bool isEager() const { return Strategy == UpdateStrategy::Eager; };
-
-  /// Returns true if it holds a DomTreeT.
-  bool hasDomTree() const { return DT != nullptr; }
-
-  /// Returns true if it holds a PostDomTreeT.
-  bool hasPostDomTree() const { return PDT != nullptr; }
-
-  /// Returns true if there is BasicBlockT awaiting deletion.
-  /// The deletion will only happen until a flush event and
-  /// all available trees are up-to-date.
-  /// Returns false under Eager UpdateStrategy.
-  bool hasPendingDeletedBB() const { return !DeletedBBs.empty(); }
-
-  /// Returns true if DelBB is awaiting deletion.
-  /// Returns false under Eager UpdateStrategy.
-  bool isBBPendingDeletion(BasicBlockT *DelBB) const {
-    if (Strategy == UpdateStrategy::Eager || DeletedBBs.empty())
-      return false;
-    return DeletedBBs.contains(DelBB);
-  }
-
-  /// Returns true if either of DT or PDT is valid and the tree has at
-  /// least one update pending. If DT or PDT is nullptr it is treated
-  /// as having no pending updates. This function does not check
-  /// whether there is MachineBasicBlock awaiting deletion.
-  /// Returns false under Eager UpdateStrategy.
-  bool hasPendingUpdates() const {
-    return hasPendingDomTreeUpdates() || hasPendingPostDomTreeUpdates();
-  }
-
-  /// Returns true if there are DomTreeT updates queued.
-  /// Returns false under Eager UpdateStrategy or DT is nullptr.
-  bool hasPendingDomTreeUpdates() const {
-    if (!DT)
-      return false;
-    return PendUpdates.size() != PendDTUpdateIndex;
-  }
-
-  /// Returns true if there are PostDomTreeT updates queued.
-  /// Returns false under Eager UpdateStrategy or PDT is nullptr.
-  bool hasPendingPostDomTreeUpdates() const {
-    if (!PDT)
-      return false;
-    return PendUpdates.size() != PendPDTUpdateIndex;
-  }
-
-  ///@{
-  /// \name Mutation APIs
-  ///
-  /// These methods provide APIs for submitting updates to the DomTreeT and
-  /// the PostDominatorTree.
-  ///
-  /// Note: There are two strategies to update the DomTreeT and the
-  /// PostDominatorTree:
-  /// 1. Eager UpdateStrategy: Updates are submitted and then flushed
-  /// immediately.
-  /// 2. Lazy UpdateStrategy: Updates are submitted but only flushed when you
-  /// explicitly call Flush APIs. It is recommended to use this update strategy
-  /// when you submit a bunch of updates multiple times which can then
-  /// add up to a large number of updates between two queries on the
-  /// DomTreeT. The incremental updater can reschedule the updates or
-  /// decide to recalculate the dominator tree in order to speedup the updating
-  /// process depending on the number of updates.
-  ///
-  /// Although GenericDomTree provides several update primitives,
-  /// it is not encouraged to use these APIs directly.
-
-  /// Notify DTU that the entry block was replaced.
-  /// Recalculate all available trees and flush all BasicBlocks
-  /// awaiting deletion immediately.
-  template <typename FuncT> void recalculate(FuncT &F) {
-    if (Strategy == UpdateStrategy::Eager) {
-      if (DT)
-        DT->recalculate(F);
-      if (PDT)
-        PDT->recalculate(F);
-      return;
-    }
-
-    // There is little performance gain if we pend the recalculation under
-    // Lazy UpdateStrategy so we recalculate available trees immediately.
-
-    // Prevent forceFlushDeletedBB() from erasing DomTree or PostDomTree nodes.
-    IsRecalculatingDomTree = IsRecalculatingPostDomTree = true;
-
-    // Because all trees are going to be up-to-date after recalculation,
-    // flush awaiting deleted BasicBlocks.
-    derived().forceFlushDeletedBB();
-    if (DT)
-      DT->recalculate(F);
-    if (PDT)
-      PDT->recalculate(F);
-
-    // Resume forceFlushDeletedBB() to erase DomTree or PostDomTree nodes.
-    IsRecalculatingDomTree = IsRecalculatingPostDomTree = false;
-    PendDTUpdateIndex = PendPDTUpdateIndex = PendUpdates.size();
-    dropOutOfDateUpdates();
-  }
-
-  /// Submit updates to all available trees.
-  /// The Eager Strategy flushes updates immediately while the Lazy Strategy
-  /// queues the updates.
-  ///
-  /// Note: The "existence" of an edge in a CFG refers to the CFG which DTU is
-  /// in sync with + all updates before that single update.
-  ///
-  /// CAUTION!
-  /// 1. It is required for the state of the LLVM IR to be updated
-  /// *before* submitting the updates because the internal update routine will
-  /// analyze the current state of the CFG to determine whether an update
-  /// is valid.
-  /// 2. It is illegal to submit any update that has already been submitted,
-  /// i.e., you are supposed not to insert an existent edge or delete a
-  /// nonexistent edge.
-  void applyUpdates(ArrayRef<typename DomTreeT::UpdateType> Updates) {
-    if (!DT && !PDT)
-      return;
-
-    if (Strategy == UpdateStrategy::Lazy) {
-      PendUpdates.reserve(PendUpdates.size() + Updates.size());
-      for (const auto &U : Updates)
-        if (!isSelfDominance(U))
-          PendUpdates.push_back(U);
-
-      return;
-    }
-
-    if (DT)
-      DT->applyUpdates(Updates);
-    if (PDT)
-      PDT->applyUpdates(Updates);
-  }
-
-  /// Submit updates to all available trees. It will also
-  /// 1. discard duplicated updates,
-  /// 2. remove invalid updates. (Invalid updates means deletion of an edge that
-  /// still exists or insertion of an edge that does not exist.)
-  /// The Eager Strategy flushes updates immediately while the Lazy Strategy
-  /// queues the updates.
-  ///
-  /// Note: The "existence" of an edge in a CFG refers to the CFG which DTU is
-  /// in sync with + all updates before that single update.
-  ///
-  /// CAUTION!
-  /// 1. It is required for the state of the LLVM IR to be updated
-  /// *before* submitting the updates because the internal update routine will
-  /// analyze the current state of the CFG to determine whether an update
-  /// is valid.
-  /// 2. It is illegal to submit any update that has already been submitted,
-  /// i.e., you are supposed not to insert an existent edge or delete a
-  /// nonexistent edge.
-  /// 3. It is only legal to submit updates to an edge in the order CFG changes
-  /// are made. The order you submit updates on 
diff erent edges is not
-  /// restricted.
-  void applyUpdatesPermissive(ArrayRef<typename DomTreeT::UpdateType> Updates) {
-    if (!DT && !PDT)
-      return;
-
-    SmallSet<std::pair<BasicBlockT *, BasicBlockT *>, 8> Seen;
-    SmallVector<typename DomTreeT::UpdateType, 8> DeduplicatedUpdates;
-    for (const auto &U : Updates) {
-      auto Edge = std::make_pair(U.getFrom(), U.getTo());
-      // Because it is illegal to submit updates that have already been applied
-      // and updates to an edge need to be strictly ordered,
-      // it is safe to infer the existence of an edge from the first update
-      // to this edge.
-      // If the first update to an edge is "Delete", it means that the edge
-      // existed before. If the first update to an edge is "Insert", it means
-      // that the edge didn't exist before.
-      //
-      // For example, if the user submits {{Delete, A, B}, {Insert, A, B}},
-      // because
-      // 1. it is illegal to submit updates that have already been applied,
-      // i.e., user cannot delete an nonexistent edge,
-      // 2. updates to an edge need to be strictly ordered,
-      // So, initially edge A -> B existed.
-      // We can then safely ignore future updates to this edge and directly
-      // inspect the current CFG:
-      // a. If the edge still exists, because the user cannot insert an existent
-      // edge, so both {Delete, A, B}, {Insert, A, B} actually happened and
-      // resulted in a no-op. DTU won't submit any update in this case.
-      // b. If the edge doesn't exist, we can then infer that {Delete, A, B}
-      // actually happened but {Insert, A, B} was an invalid update which never
-      // happened. DTU will submit {Delete, A, B} in this case.
-      if (!isSelfDominance(U) && Seen.count(Edge) == 0) {
-        Seen.insert(Edge);
-        // If the update doesn't appear in the CFG, it means that
-        // either the change isn't made or relevant operations
-        // result in a no-op.
-        if (isUpdateValid(U)) {
-          if (isLazy())
-            PendUpdates.push_back(U);
-          else
-            DeduplicatedUpdates.push_back(U);
-        }
-      }
-    }
-
-    if (Strategy == UpdateStrategy::Lazy)
-      return;
-
-    if (DT)
-      DT->applyUpdates(DeduplicatedUpdates);
-    if (PDT)
-      PDT->applyUpdates(DeduplicatedUpdates);
-  }
-
-  ///@}
-
-  ///@{
-  /// \name Flush APIs
-  ///
-  /// CAUTION! By the moment these flush APIs are called, the current CFG needs
-  /// to be the same as the CFG which DTU is in sync with + all updates
-  /// submitted.
-
-  /// Flush DomTree updates and return DomTree.
-  /// It flushes Deleted BBs if both trees are up-to-date.
-  /// It must only be called when it has a DomTree.
-  DomTreeT &getDomTree() {
-    assert(DT && "Invalid acquisition of a null DomTree");
-    applyDomTreeUpdates();
-    dropOutOfDateUpdates();
-    return *DT;
-  }
-
-  /// Flush PostDomTree updates and return PostDomTree.
-  /// It flushes Deleted BBs if both trees are up-to-date.
-  /// It must only be called when it has a PostDomTree.
-  PostDomTreeT &getPostDomTree() {
-    assert(PDT && "Invalid acquisition of a null PostDomTree");
-    applyPostDomTreeUpdates();
-    dropOutOfDateUpdates();
-    return *PDT;
-  }
-
-  /// Apply all pending updates to available trees and flush all BasicBlocks
-  /// awaiting deletion.
-
-  void flush() {
-    applyDomTreeUpdates();
-    applyPostDomTreeUpdates();
-    dropOutOfDateUpdates();
-  }
-
-  ///@}
-
-  /// Debug method to help view the internal state of this class.
-  LLVM_DUMP_METHOD void dump() const {
-#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
-    raw_ostream &OS = llvm::dbgs();
-
-    OS << "Available Trees: ";
-    if (DT || PDT) {
-      if (DT)
-        OS << "DomTree ";
-      if (PDT)
-        OS << "PostDomTree ";
-      OS << "\n";
-    } else
-      OS << "None\n";
-
-    OS << "UpdateStrategy: ";
-    if (Strategy == UpdateStrategy::Eager) {
-      OS << "Eager\n";
-      return;
-    } else
-      OS << "Lazy\n";
-    int Index = 0;
-
-    auto printUpdates =
-        [&](typename ArrayRef<typename DomTreeT::UpdateType>::const_iterator
-                begin,
-            typename ArrayRef<typename DomTreeT::UpdateType>::const_iterator
-                end) {
-          if (begin == end)
-            OS << "  None\n";
-          Index = 0;
-          for (auto It = begin, ItEnd = end; It != ItEnd; ++It) {
-            auto U = *It;
-            OS << "  " << Index << " : ";
-            ++Index;
-            if (U.getKind() == DomTreeT::Insert)
-              OS << "Insert, ";
-            else
-              OS << "Delete, ";
-            BasicBlockT *From = U.getFrom();
-            if (From) {
-              auto S = From->getName();
-              if (!From->hasName())
-                S = "(no name)";
-              OS << S << "(" << From << "), ";
-            } else {
-              OS << "(badref), ";
-            }
-            BasicBlockT *To = U.getTo();
-            if (To) {
-              auto S = To->getName();
-              if (!To->hasName())
-                S = "(no_name)";
-              OS << S << "(" << To << ")\n";
-            } else {
-              OS << "(badref)\n";
-            }
-          }
-        };
-
-    if (DT) {
-      const auto I = PendUpdates.begin() + PendDTUpdateIndex;
-      assert(PendUpdates.begin() <= I && I <= PendUpdates.end() &&
-             "Iterator out of range.");
-      OS << "Applied but not cleared DomTreeUpdates:\n";
-      printUpdates(PendUpdates.begin(), I);
-      OS << "Pending DomTreeUpdates:\n";
-      printUpdates(I, PendUpdates.end());
-    }
-
-    if (PDT) {
-      const auto I = PendUpdates.begin() + PendPDTUpdateIndex;
-      assert(PendUpdates.begin() <= I && I <= PendUpdates.end() &&
-             "Iterator out of range.");
-      OS << "Applied but not cleared PostDomTreeUpdates:\n";
-      printUpdates(PendUpdates.begin(), I);
-      OS << "Pending PostDomTreeUpdates:\n";
-      printUpdates(I, PendUpdates.end());
-    }
-
-    OS << "Pending DeletedBBs:\n";
-    Index = 0;
-    for (const auto *BB : DeletedBBs) {
-      OS << "  " << Index << " : ";
-      ++Index;
-      if (BB->hasName())
-        OS << BB->getName() << "(";
-      else
-        OS << "(no_name)(";
-      OS << BB << ")\n";
-    }
-#endif
-  }
-
-protected:
-  SmallVector<typename DomTreeT::UpdateType, 16> PendUpdates;
-  size_t PendDTUpdateIndex = 0;
-  size_t PendPDTUpdateIndex = 0;
-  DomTreeT *DT = nullptr;
-  PostDomTreeT *PDT = nullptr;
-  const UpdateStrategy Strategy;
-  SmallPtrSet<BasicBlockT *, 8> DeletedBBs;
-  bool IsRecalculatingDomTree = false;
-  bool IsRecalculatingPostDomTree = false;
-
-  /// Returns true if the update is self dominance.
-  bool isSelfDominance(typename DomTreeT::UpdateType Update) const {
-    // Won't affect DomTree and PostDomTree.
-    return Update.getFrom() == Update.getTo();
-  }
-
-  /// Helper function to apply all pending DomTree updates.
-  void applyDomTreeUpdates() {
-    // No pending DomTreeUpdates.
-    if (Strategy != UpdateStrategy::Lazy || !DT)
-      return;
-
-    // Only apply updates not are applied by DomTree.
-    if (hasPendingDomTreeUpdates()) {
-      const auto I = PendUpdates.begin() + PendDTUpdateIndex;
-      const auto E = PendUpdates.end();
-      assert(I < E &&
-             "Iterator range invalid; there should be DomTree updates.");
-      DT->applyUpdates(ArrayRef<typename DomTreeT::UpdateType>(I, E));
-      PendDTUpdateIndex = PendUpdates.size();
-    }
-  }
-
-  /// Helper function to apply all pending PostDomTree updates.
-  void applyPostDomTreeUpdates() {
-    // No pending PostDomTreeUpdates.
-    if (Strategy != UpdateStrategy::Lazy || !PDT)
-      return;
-
-    // Only apply updates not are applied by PostDomTree.
-    if (hasPendingPostDomTreeUpdates()) {
-      const auto I = PendUpdates.begin() + PendPDTUpdateIndex;
-      const auto E = PendUpdates.end();
-      assert(I < E &&
-             "Iterator range invalid; there should be PostDomTree updates.");
-      PDT->applyUpdates(ArrayRef<typename DomTreeT::UpdateType>(I, E));
-      PendPDTUpdateIndex = PendUpdates.size();
-    }
-  }
-
-  /// Returns true if the update appears in the LLVM IR.
-  /// It is used to check whether an update is valid in
-  /// insertEdge/deleteEdge or is unnecessary in the batch update.
-  bool isUpdateValid(typename DomTreeT::UpdateType Update) const {
-    const auto *From = Update.getFrom();
-    const auto *To = Update.getTo();
-    const auto Kind = Update.getKind();
-
-    // Discard updates by inspecting the current state of successors of From.
-    // Since isUpdateValid() must be called *after* the Terminator of From is
-    // altered we can determine if the update is unnecessary for batch updates
-    // or invalid for a single update.
-    const bool HasEdge = llvm::is_contained(successors(From), To);
-
-    // If the IR does not match the update,
-    // 1. In batch updates, this update is unnecessary.
-    // 2. When called by insertEdge*()/deleteEdge*(), this update is invalid.
-    // Edge does not exist in IR.
-    if (Kind == DomTreeT::Insert && !HasEdge)
-      return false;
-
-    // Edge exists in IR.
-    if (Kind == DomTreeT::Delete && HasEdge)
-      return false;
-
-    return true;
-  }
-
-  /// Erase Basic Block node that has been unlinked from Function
-  /// in the DomTree and PostDomTree.
-  void eraseDelBBNode(BasicBlockT *DelBB) {
-    if (DT && !IsRecalculatingDomTree)
-      if (DT->getNode(DelBB))
-        DT->eraseNode(DelBB);
-
-    if (PDT && !IsRecalculatingPostDomTree)
-      if (PDT->getNode(DelBB))
-        PDT->eraseNode(DelBB);
-  }
-
-  /// Helper function to flush deleted BasicBlocks if all available
-  /// trees are up-to-date.
-  void tryFlushDeletedBB() {
-    if (!hasPendingUpdates())
-      derived().forceFlushDeletedBB();
-  }
-
-  /// Drop all updates applied by all available trees and delete BasicBlocks if
-  /// all available trees are up-to-date.
-  void dropOutOfDateUpdates() {
-    if (Strategy == UpdateStrategy::Eager)
-      return;
-
-    tryFlushDeletedBB();
-
-    // Drop all updates applied by both trees.
-    if (!DT)
-      PendDTUpdateIndex = PendUpdates.size();
-    if (!PDT)
-      PendPDTUpdateIndex = PendUpdates.size();
-
-    const size_t dropIndex = std::min(PendDTUpdateIndex, PendPDTUpdateIndex);
-    const auto B = PendUpdates.begin();
-    const auto E = PendUpdates.begin() + dropIndex;
-    assert(B <= E && "Iterator out of range.");
-    PendUpdates.erase(B, E);
-    // Calculate current index.
-    PendDTUpdateIndex -= dropIndex;
-    PendPDTUpdateIndex -= dropIndex;
-  }
-};
-
-} // namespace llvm
-
-#endif // LLVM_ANALYSIS_GENERICDOMTREEUPDATER_H

diff  --git a/llvm/include/llvm/CodeGen/MachineBasicBlock.h b/llvm/include/llvm/CodeGen/MachineBasicBlock.h
index e4919ecabd705..5b6be3a96b2fb 100644
--- a/llvm/include/llvm/CodeGen/MachineBasicBlock.h
+++ b/llvm/include/llvm/CodeGen/MachineBasicBlock.h
@@ -238,9 +238,6 @@ class MachineBasicBlock
     BB = nullptr;
   }
 
-  /// Check if there is a name of corresponding LLVM basic block.
-  bool hasName() const;
-
   /// Return the name of the corresponding LLVM basic block, or an empty string.
   StringRef getName() const;
 

diff  --git a/llvm/include/llvm/CodeGen/MachineDomTreeUpdater.h b/llvm/include/llvm/CodeGen/MachineDomTreeUpdater.h
deleted file mode 100644
index 8bc572e6e6af0..0000000000000
--- a/llvm/include/llvm/CodeGen/MachineDomTreeUpdater.h
+++ /dev/null
@@ -1,72 +0,0 @@
-//===- llvm/CodeGen/MachineDomTreeUpdater.h -----------------------*- C++
-//-*-==//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-//
-// This file exposes interfaces to post dominance information for
-// target-specific code.
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef LLVM_CODEGEN_MACHINEDOMTREEUPDATER_H
-#define LLVM_CODEGEN_MACHINEDOMTREEUPDATER_H
-
-#include "llvm/ADT/SmallPtrSet.h"
-#include "llvm/Analysis/GenericDomTreeUpdater.h"
-#include "llvm/CodeGen/MachineDominators.h"
-#include "llvm/CodeGen/MachinePostDominators.h"
-#include "llvm/IR/ValueHandle.h"
-#include "llvm/Support/Compiler.h"
-#include <cstddef>
-#include <functional>
-#include <vector>
-
-namespace llvm {
-
-class MachineDomTreeUpdater
-    : public GenericDomTreeUpdater<MachineDomTreeUpdater, MachineDominatorTree,
-                                   MachinePostDominatorTree> {
-  friend GenericDomTreeUpdater<MachineDomTreeUpdater, MachineDominatorTree,
-                               MachinePostDominatorTree>;
-
-public:
-  using Base =
-      GenericDomTreeUpdater<MachineDomTreeUpdater, MachineDominatorTree,
-                            MachinePostDominatorTree>;
-  using Base::Base;
-
-  ///@{
-  /// \name Mutation APIs
-  ///
-
-  /// Delete DelBB. DelBB will be removed from its Parent and
-  /// erased from available trees if it exists and finally get deleted.
-  /// Under Eager UpdateStrategy, DelBB will be processed immediately.
-  /// Under Lazy UpdateStrategy, DelBB will be queued until a flush event and
-  /// all available trees are up-to-date. Assert if any instruction of DelBB is
-  /// modified while awaiting deletion. When both DT and PDT are nullptrs, DelBB
-  /// will be queued until flush() is called.
-  void deleteBB(MachineBasicBlock *DelBB);
-
-  ///@}
-
-private:
-  /// First remove all the instructions of DelBB and then make sure DelBB has a
-  /// valid terminator instruction which is necessary to have when DelBB still
-  /// has to be inside of its parent Function while awaiting deletion under Lazy
-  /// UpdateStrategy to prevent other routines from asserting the state of the
-  /// IR is inconsistent. Assert if DelBB is nullptr or has predecessors.
-  void validateDeleteBB(MachineBasicBlock *DelBB);
-
-  /// Returns true if at least one MachineBasicBlock is deleted.
-  bool forceFlushDeletedBB();
-};
-
-extern template class GenericDomTreeUpdater<
-    MachineDomTreeUpdater, MachineDominatorTree, MachinePostDominatorTree>;
-} // namespace llvm
-#endif // LLVM_CODEGEN_MACHINEDOMTREEUPDATER_H

diff  --git a/llvm/include/llvm/CodeGen/MachinePostDominators.h b/llvm/include/llvm/CodeGen/MachinePostDominators.h
index 58cfb278b7962..904c5fcdfc68b 100644
--- a/llvm/include/llvm/CodeGen/MachinePostDominators.h
+++ b/llvm/include/llvm/CodeGen/MachinePostDominators.h
@@ -48,7 +48,6 @@ class MachinePostDominatorTree : public PostDomTreeBase<MachineBasicBlock> {
 
 public:
   MachinePostDominatorTree() = default;
-  explicit MachinePostDominatorTree(MachineFunction &MF) { recalculate(MF); }
 
   MachinePostDominatorTree(MachineFunction &MF) { recalculate(MF); }
 

diff  --git a/llvm/lib/Analysis/DomTreeUpdater.cpp b/llvm/lib/Analysis/DomTreeUpdater.cpp
index 676cb87210176..0a16fc9a76d29 100644
--- a/llvm/lib/Analysis/DomTreeUpdater.cpp
+++ b/llvm/lib/Analysis/DomTreeUpdater.cpp
@@ -23,8 +23,79 @@
 
 namespace llvm {
 
-template class GenericDomTreeUpdater<DomTreeUpdater, DominatorTree,
-                                     PostDominatorTree>;
+bool DomTreeUpdater::isUpdateValid(
+    const DominatorTree::UpdateType Update) const {
+  const auto *From = Update.getFrom();
+  const auto *To = Update.getTo();
+  const auto Kind = Update.getKind();
+
+  // Discard updates by inspecting the current state of successors of From.
+  // Since isUpdateValid() must be called *after* the Terminator of From is
+  // altered we can determine if the update is unnecessary for batch updates
+  // or invalid for a single update.
+  const bool HasEdge = llvm::is_contained(successors(From), To);
+
+  // If the IR does not match the update,
+  // 1. In batch updates, this update is unnecessary.
+  // 2. When called by insertEdge*()/deleteEdge*(), this update is invalid.
+  // Edge does not exist in IR.
+  if (Kind == DominatorTree::Insert && !HasEdge)
+    return false;
+
+  // Edge exists in IR.
+  if (Kind == DominatorTree::Delete && HasEdge)
+    return false;
+
+  return true;
+}
+
+bool DomTreeUpdater::isSelfDominance(
+    const DominatorTree::UpdateType Update) const {
+  // Won't affect DomTree and PostDomTree.
+  return Update.getFrom() == Update.getTo();
+}
+
+void DomTreeUpdater::applyDomTreeUpdates() {
+  // No pending DomTreeUpdates.
+  if (Strategy != UpdateStrategy::Lazy || !DT)
+    return;
+
+  // Only apply updates not are applied by DomTree.
+  if (hasPendingDomTreeUpdates()) {
+    const auto I = PendUpdates.begin() + PendDTUpdateIndex;
+    const auto E = PendUpdates.end();
+    assert(I < E && "Iterator range invalid; there should be DomTree updates.");
+    DT->applyUpdates(ArrayRef<DominatorTree::UpdateType>(I, E));
+    PendDTUpdateIndex = PendUpdates.size();
+  }
+}
+
+void DomTreeUpdater::flush() {
+  applyDomTreeUpdates();
+  applyPostDomTreeUpdates();
+  dropOutOfDateUpdates();
+}
+
+void DomTreeUpdater::applyPostDomTreeUpdates() {
+  // No pending PostDomTreeUpdates.
+  if (Strategy != UpdateStrategy::Lazy || !PDT)
+    return;
+
+  // Only apply updates not are applied by PostDomTree.
+  if (hasPendingPostDomTreeUpdates()) {
+    const auto I = PendUpdates.begin() + PendPDTUpdateIndex;
+    const auto E = PendUpdates.end();
+    assert(I < E &&
+           "Iterator range invalid; there should be PostDomTree updates.");
+    PDT->applyUpdates(ArrayRef<DominatorTree::UpdateType>(I, E));
+    PendPDTUpdateIndex = PendUpdates.size();
+  }
+}
+
+void DomTreeUpdater::tryFlushDeletedBB() {
+  if (!hasPendingUpdates())
+    forceFlushDeletedBB();
+}
 
 bool DomTreeUpdater::forceFlushDeletedBB() {
   if (DeletedBBs.empty())
@@ -46,6 +117,58 @@ bool DomTreeUpdater::forceFlushDeletedBB() {
   return true;
 }
 
+void DomTreeUpdater::recalculate(Function &F) {
+
+  if (Strategy == UpdateStrategy::Eager) {
+    if (DT)
+      DT->recalculate(F);
+    if (PDT)
+      PDT->recalculate(F);
+    return;
+  }
+
+  // There is little performance gain if we pend the recalculation under
+  // Lazy UpdateStrategy so we recalculate available trees immediately.
+
+  // Prevent forceFlushDeletedBB() from erasing DomTree or PostDomTree nodes.
+  IsRecalculatingDomTree = IsRecalculatingPostDomTree = true;
+
+  // Because all trees are going to be up-to-date after recalculation,
+  // flush awaiting deleted BasicBlocks.
+  forceFlushDeletedBB();
+  if (DT)
+    DT->recalculate(F);
+  if (PDT)
+    PDT->recalculate(F);
+
+  // Resume forceFlushDeletedBB() to erase DomTree or PostDomTree nodes.
+  IsRecalculatingDomTree = IsRecalculatingPostDomTree = false;
+  PendDTUpdateIndex = PendPDTUpdateIndex = PendUpdates.size();
+  dropOutOfDateUpdates();
+}
+
+bool DomTreeUpdater::hasPendingUpdates() const {
+  return hasPendingDomTreeUpdates() || hasPendingPostDomTreeUpdates();
+}
+
+bool DomTreeUpdater::hasPendingDomTreeUpdates() const {
+  if (!DT)
+    return false;
+  return PendUpdates.size() != PendDTUpdateIndex;
+}
+
+bool DomTreeUpdater::hasPendingPostDomTreeUpdates() const {
+  if (!PDT)
+    return false;
+  return PendUpdates.size() != PendPDTUpdateIndex;
+}
+
+bool DomTreeUpdater::isBBPendingDeletion(llvm::BasicBlock *DelBB) const {
+  if (Strategy == UpdateStrategy::Eager || DeletedBBs.empty())
+    return false;
+  return DeletedBBs.contains(DelBB);
+}
+
 // The DT and PDT require the nodes related to updates
 // are not deleted when update functions are called.
 // So BasicBlock deletions must be pended when the
@@ -78,6 +201,16 @@ void DomTreeUpdater::callbackDeleteBB(
   delete DelBB;
 }
 
+void DomTreeUpdater::eraseDelBBNode(BasicBlock *DelBB) {
+  if (DT && !IsRecalculatingDomTree)
+    if (DT->getNode(DelBB))
+      DT->eraseNode(DelBB);
+
+  if (PDT && !IsRecalculatingPostDomTree)
+    if (PDT->getNode(DelBB))
+      PDT->eraseNode(DelBB);
+}
+
 void DomTreeUpdater::validateDeleteBB(BasicBlock *DelBB) {
   assert(DelBB && "Invalid push_back of nullptr DelBB.");
   assert(pred_empty(DelBB) && "DelBB has one or more predecessors.");
@@ -94,4 +227,215 @@ void DomTreeUpdater::validateDeleteBB(BasicBlock *DelBB) {
   new UnreachableInst(DelBB->getContext(), DelBB);
 }
 
+void DomTreeUpdater::applyUpdates(ArrayRef<DominatorTree::UpdateType> Updates) {
+  if (!DT && !PDT)
+    return;
+
+  if (Strategy == UpdateStrategy::Lazy) {
+    PendUpdates.reserve(PendUpdates.size() + Updates.size());
+    for (const auto &U : Updates)
+      if (!isSelfDominance(U))
+        PendUpdates.push_back(U);
+
+    return;
+  }
+
+  if (DT)
+    DT->applyUpdates(Updates);
+  if (PDT)
+    PDT->applyUpdates(Updates);
+}
+
+void DomTreeUpdater::applyUpdatesPermissive(
+    ArrayRef<DominatorTree::UpdateType> Updates) {
+  if (!DT && !PDT)
+    return;
+
+  SmallSet<std::pair<BasicBlock *, BasicBlock *>, 8> Seen;
+  SmallVector<DominatorTree::UpdateType, 8> DeduplicatedUpdates;
+  for (const auto &U : Updates) {
+    auto Edge = std::make_pair(U.getFrom(), U.getTo());
+    // Because it is illegal to submit updates that have already been applied
+    // and updates to an edge need to be strictly ordered,
+    // it is safe to infer the existence of an edge from the first update
+    // to this edge.
+    // If the first update to an edge is "Delete", it means that the edge
+    // existed before. If the first update to an edge is "Insert", it means
+    // that the edge didn't exist before.
+    //
+    // For example, if the user submits {{Delete, A, B}, {Insert, A, B}},
+    // because
+    // 1. it is illegal to submit updates that have already been applied,
+    // i.e., user cannot delete an nonexistent edge,
+    // 2. updates to an edge need to be strictly ordered,
+    // So, initially edge A -> B existed.
+    // We can then safely ignore future updates to this edge and directly
+    // inspect the current CFG:
+    // a. If the edge still exists, because the user cannot insert an existent
+    // edge, so both {Delete, A, B}, {Insert, A, B} actually happened and
+    // resulted in a no-op. DTU won't submit any update in this case.
+    // b. If the edge doesn't exist, we can then infer that {Delete, A, B}
+    // actually happened but {Insert, A, B} was an invalid update which never
+    // happened. DTU will submit {Delete, A, B} in this case.
+    if (!isSelfDominance(U) && Seen.count(Edge) == 0) {
+      Seen.insert(Edge);
+      // If the update doesn't appear in the CFG, it means that
+      // either the change isn't made or relevant operations
+      // result in a no-op.
+      if (isUpdateValid(U)) {
+        if (isLazy())
+          PendUpdates.push_back(U);
+        else
+          DeduplicatedUpdates.push_back(U);
+      }
+    }
+  }
+
+  if (Strategy == UpdateStrategy::Lazy)
+    return;
+
+  if (DT)
+    DT->applyUpdates(DeduplicatedUpdates);
+  if (PDT)
+    PDT->applyUpdates(DeduplicatedUpdates);
+}
+
+DominatorTree &DomTreeUpdater::getDomTree() {
+  assert(DT && "Invalid acquisition of a null DomTree");
+  applyDomTreeUpdates();
+  dropOutOfDateUpdates();
+  return *DT;
+}
+
+PostDominatorTree &DomTreeUpdater::getPostDomTree() {
+  assert(PDT && "Invalid acquisition of a null PostDomTree");
+  applyPostDomTreeUpdates();
+  dropOutOfDateUpdates();
+  return *PDT;
+}
+
+void DomTreeUpdater::dropOutOfDateUpdates() {
+  if (Strategy == DomTreeUpdater::UpdateStrategy::Eager)
+    return;
+
+  tryFlushDeletedBB();
+
+  // Drop all updates applied by both trees.
+  if (!DT)
+    PendDTUpdateIndex = PendUpdates.size();
+  if (!PDT)
+    PendPDTUpdateIndex = PendUpdates.size();
+
+  const size_t dropIndex = std::min(PendDTUpdateIndex, PendPDTUpdateIndex);
+  const auto B = PendUpdates.begin();
+  const auto E = PendUpdates.begin() + dropIndex;
+  assert(B <= E && "Iterator out of range.");
+  PendUpdates.erase(B, E);
+  // Calculate current index.
+  PendDTUpdateIndex -= dropIndex;
+  PendPDTUpdateIndex -= dropIndex;
+}
+
+#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
+LLVM_DUMP_METHOD void DomTreeUpdater::dump() const {
+  raw_ostream &OS = llvm::dbgs();
+
+  OS << "Available Trees: ";
+  if (DT || PDT) {
+    if (DT)
+      OS << "DomTree ";
+    if (PDT)
+      OS << "PostDomTree ";
+    OS << "\n";
+  } else
+    OS << "None\n";
+
+  OS << "UpdateStrategy: ";
+  if (Strategy == UpdateStrategy::Eager) {
+    OS << "Eager\n";
+    return;
+  } else
+    OS << "Lazy\n";
+  int Index = 0;
+
+  auto printUpdates =
+      [&](ArrayRef<DominatorTree::UpdateType>::const_iterator begin,
+          ArrayRef<DominatorTree::UpdateType>::const_iterator end) {
+        if (begin == end)
+          OS << "  None\n";
+        Index = 0;
+        for (auto It = begin, ItEnd = end; It != ItEnd; ++It) {
+          auto U = *It;
+          OS << "  " << Index << " : ";
+          ++Index;
+          if (U.getKind() == DominatorTree::Insert)
+            OS << "Insert, ";
+          else
+            OS << "Delete, ";
+          BasicBlock *From = U.getFrom();
+          if (From) {
+            auto S = From->getName();
+            if (!From->hasName())
+              S = "(no name)";
+            OS << S << "(" << From << "), ";
+          } else {
+            OS << "(badref), ";
+          }
+          BasicBlock *To = U.getTo();
+          if (To) {
+            auto S = To->getName();
+            if (!To->hasName())
+              S = "(no_name)";
+            OS << S << "(" << To << ")\n";
+          } else {
+            OS << "(badref)\n";
+          }
+        }
+      };
+
+  if (DT) {
+    const auto I = PendUpdates.begin() + PendDTUpdateIndex;
+    assert(PendUpdates.begin() <= I && I <= PendUpdates.end() &&
+           "Iterator out of range.");
+    OS << "Applied but not cleared DomTreeUpdates:\n";
+    printUpdates(PendUpdates.begin(), I);
+    OS << "Pending DomTreeUpdates:\n";
+    printUpdates(I, PendUpdates.end());
+  }
+
+  if (PDT) {
+    const auto I = PendUpdates.begin() + PendPDTUpdateIndex;
+    assert(PendUpdates.begin() <= I && I <= PendUpdates.end() &&
+           "Iterator out of range.");
+    OS << "Applied but not cleared PostDomTreeUpdates:\n";
+    printUpdates(PendUpdates.begin(), I);
+    OS << "Pending PostDomTreeUpdates:\n";
+    printUpdates(I, PendUpdates.end());
+  }
+
+  OS << "Pending DeletedBBs:\n";
+  Index = 0;
+  for (const auto *BB : DeletedBBs) {
+    OS << "  " << Index << " : ";
+    ++Index;
+    if (BB->hasName())
+      OS << BB->getName() << "(";
+    else
+      OS << "(no_name)(";
+    OS << BB << ")\n";
+  }
+
+  OS << "Pending Callbacks:\n";
+  Index = 0;
+  for (const auto &BB : Callbacks) {
+    OS << "  " << Index << " : ";
+    ++Index;
+    if (BB->hasName())
+      OS << BB->getName() << "(";
+    else
+      OS << "(no_name)(";
+    OS << BB << ")\n";
+  }
+}
+#endif
 } // namespace llvm

diff  --git a/llvm/lib/CodeGen/CMakeLists.txt b/llvm/lib/CodeGen/CMakeLists.txt
index f1607f85c5b31..41fc555c93e93 100644
--- a/llvm/lib/CodeGen/CMakeLists.txt
+++ b/llvm/lib/CodeGen/CMakeLists.txt
@@ -116,7 +116,6 @@ add_llvm_component_library(LLVMCodeGen
   MachineCheckDebugify.cpp
   MachineCycleAnalysis.cpp
   MachineDebugify.cpp
-  MachineDomTreeUpdater.cpp
   MachineDominanceFrontier.cpp
   MachineDominators.cpp
   MachineFrameInfo.cpp

diff  --git a/llvm/lib/CodeGen/MachineBasicBlock.cpp b/llvm/lib/CodeGen/MachineBasicBlock.cpp
index 533ab7cccaeb7..abf43e39ee9a6 100644
--- a/llvm/lib/CodeGen/MachineBasicBlock.cpp
+++ b/llvm/lib/CodeGen/MachineBasicBlock.cpp
@@ -315,12 +315,6 @@ bool MachineBasicBlock::isLegalToHoistInto() const {
   return true;
 }
 
-bool MachineBasicBlock::hasName() const {
-  if (const BasicBlock *LBB = getBasicBlock())
-    return LBB->hasName();
-  return false;
-}
-
 StringRef MachineBasicBlock::getName() const {
   if (const BasicBlock *LBB = getBasicBlock())
     return LBB->getName();

diff  --git a/llvm/lib/CodeGen/MachineDomTreeUpdater.cpp b/llvm/lib/CodeGen/MachineDomTreeUpdater.cpp
deleted file mode 100644
index 86b3185ca90a3..0000000000000
--- a/llvm/lib/CodeGen/MachineDomTreeUpdater.cpp
+++ /dev/null
@@ -1,62 +0,0 @@
-//===- MachineDomTreeUpdater.cpp -----------------------------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-//
-// This file implements the MachineDomTreeUpdater class, which provides a
-// uniform way to update dominator tree related data structures.
-//
-//===----------------------------------------------------------------------===//
-
-#include "llvm/CodeGen/MachineDomTreeUpdater.h"
-#include "llvm/ADT/SmallSet.h"
-#include "llvm/CodeGen/MachinePostDominators.h"
-#include "llvm/IR/Constants.h"
-#include "llvm/IR/Instructions.h"
-#include "llvm/Support/GenericDomTree.h"
-#include <algorithm>
-#include <functional>
-#include <utility>
-
-namespace llvm {
-
-template class GenericDomTreeUpdater<
-    MachineDomTreeUpdater, MachineDominatorTree, MachinePostDominatorTree>;
-
-bool MachineDomTreeUpdater::forceFlushDeletedBB() {
-  if (DeletedBBs.empty())
-    return false;
-
-  for (auto *BB : DeletedBBs) {
-    eraseDelBBNode(BB);
-    BB->eraseFromParent();
-  }
-  DeletedBBs.clear();
-  return true;
-}
-
-// The DT and PDT require the nodes related to updates
-// are not deleted when update functions are called.
-// So MachineBasicBlock deletions must be pended when the
-// UpdateStrategy is Lazy. When the UpdateStrategy is
-// Eager, the MachineBasicBlock will be deleted immediately.
-void MachineDomTreeUpdater::deleteBB(MachineBasicBlock *DelBB) {
-  validateDeleteBB(DelBB);
-  if (Strategy == UpdateStrategy::Lazy) {
-    DeletedBBs.insert(DelBB);
-    return;
-  }
-
-  eraseDelBBNode(DelBB);
-  DelBB->eraseFromParent();
-}
-
-void MachineDomTreeUpdater::validateDeleteBB(MachineBasicBlock *DelBB) {
-  assert(DelBB && "Invalid push_back of nullptr DelBB.");
-  assert(DelBB->pred_empty() && "DelBB has one or more predecessors.");
-}
-
-} // namespace llvm

diff  --git a/llvm/unittests/CodeGen/CMakeLists.txt b/llvm/unittests/CodeGen/CMakeLists.txt
index 963cdcc0275e1..dbbacdd95ec9f 100644
--- a/llvm/unittests/CodeGen/CMakeLists.txt
+++ b/llvm/unittests/CodeGen/CMakeLists.txt
@@ -32,7 +32,6 @@ add_llvm_unittest(CodeGenTests
   LowLevelTypeTest.cpp
   LexicalScopesTest.cpp
   MachineBasicBlockTest.cpp
-  MachineDomTreeUpdaterTest.cpp
   MachineInstrBundleIteratorTest.cpp
   MachineInstrTest.cpp
   MachineOperandTest.cpp

diff  --git a/llvm/unittests/CodeGen/MachineDomTreeUpdaterTest.cpp b/llvm/unittests/CodeGen/MachineDomTreeUpdaterTest.cpp
deleted file mode 100644
index e123ba847e622..0000000000000
--- a/llvm/unittests/CodeGen/MachineDomTreeUpdaterTest.cpp
+++ /dev/null
@@ -1,276 +0,0 @@
-//===- MachineDomTreeUpdaterTest.cpp - MachineDomTreeUpdater unit tests ---===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-#include "llvm/CodeGen/MachineDomTreeUpdater.h"
-#include "llvm/Analysis/CGSCCPassManager.h"
-#include "llvm/Analysis/LoopAnalysisManager.h"
-#include "llvm/CodeGen/MIRParser/MIRParser.h"
-#include "llvm/CodeGen/MachineFunctionAnalysis.h"
-#include "llvm/CodeGen/MachineModuleInfo.h"
-#include "llvm/CodeGen/MachinePassManager.h"
-#include "llvm/CodeGen/MachinePostDominators.h"
-#include "llvm/CodeGen/SelectionDAG.h"
-#include "llvm/CodeGen/TargetLowering.h"
-#include "llvm/MC/TargetRegistry.h"
-#include "llvm/Passes/PassBuilder.h"
-#include "llvm/Support/SourceMgr.h"
-#include "llvm/Support/TargetSelect.h"
-#include "llvm/Target/TargetMachine.h"
-#include "gtest/gtest.h"
-
-using namespace llvm;
-
-class MachineDomTreeUpdaterTest : public testing::Test {
-public:
-  LLVMContext Context;
-  std::unique_ptr<TargetMachine> TM;
-  std::unique_ptr<Module> M;
-  std::unique_ptr<MachineModuleInfo> MMI;
-  std::unique_ptr<MIRParser> MIR;
-
-  LoopAnalysisManager LAM;
-  MachineFunctionAnalysisManager MFAM;
-  FunctionAnalysisManager FAM;
-  CGSCCAnalysisManager CGAM;
-  ModuleAnalysisManager MAM;
-
-  ModulePassManager MPM;
-  FunctionPassManager FPM;
-  MachineFunctionPassManager MFPM;
-
-  static void SetUpTestCase() {
-    InitializeAllTargets();
-    InitializeAllTargetMCs();
-  }
-
-  void SetUp() override {
-    Triple TargetTriple("x86_64-unknown-linux-gnu");
-    std::string Error;
-    const Target *T = TargetRegistry::lookupTarget("", TargetTriple, Error);
-    if (!T)
-      GTEST_SKIP();
-    TargetOptions Options;
-    TM = std::unique_ptr<TargetMachine>(
-        T->createTargetMachine("X86", "", "", Options, std::nullopt));
-    if (!TM)
-      GTEST_SKIP();
-    MMI = std::make_unique<MachineModuleInfo>(
-        static_cast<LLVMTargetMachine *>(TM.get()));
-
-    PassBuilder PB(TM.get());
-    PB.registerModuleAnalyses(MAM);
-    PB.registerCGSCCAnalyses(CGAM);
-    PB.registerFunctionAnalyses(FAM);
-    PB.registerLoopAnalyses(LAM);
-    PB.registerMachineFunctionAnalyses(MFAM);
-    PB.crossRegisterProxies(LAM, FAM, CGAM, MAM, &MFAM);
-    MAM.registerPass([&] { return MachineModuleAnalysis(*MMI); });
-  }
-
-  bool parseMIR(StringRef MIRCode, const char *FnName) {
-    SMDiagnostic Diagnostic;
-    std::unique_ptr<MemoryBuffer> MBuffer = MemoryBuffer::getMemBuffer(MIRCode);
-    MIR = createMIRParser(std::move(MBuffer), Context);
-    if (!MIR)
-      return false;
-
-    M = MIR->parseIRModule();
-    M->setDataLayout(TM->createDataLayout());
-
-    if (MIR->parseMachineFunctions(*M, MAM)) {
-      M.reset();
-      return false;
-    }
-
-    return true;
-  }
-};
-
-TEST_F(MachineDomTreeUpdaterTest, EagerUpdateBasicOperations) {
-  StringRef MIRString = R"(
---- |
-  define i64 @f0(i64 %i, ptr %p) {
-  bb0:
-    store i64 %i, ptr %p, align 4
-    switch i64 %i, label %bb1 [
-      i64 1, label %bb2
-      i64 2, label %bb3
-    ]
-  bb1:                                              ; preds = %bb0
-    ret i64 1
-  bb2:                                              ; preds = %bb0
-    ret i64 2
-  bb3:                                              ; preds = %bb0
-    ret i64 3
-  }
-...
----
-name:            f0
-body:             |
-  bb.0.bb0:
-    successors: %bb.2, %bb.4
-    liveins: $rdi, $rsi
-
-    %1:gr32 = COPY $rsi
-    %0:gr64 = COPY $rdi
-    MOV64mr %1, 1, $noreg, 0, $noreg, %0 :: (store (s64) into %ir.p)
-    %2:gr64 = SUB64ri32 %0, 1, implicit-def $eflags
-    JCC_1 %bb.2, 4, implicit $eflags
-    JMP_1 %bb.4
-
-  bb.4.bb0:
-    successors: %bb.3, %bb.1
-
-    %3:gr64 = SUB64ri32 %0, 2, implicit-def $eflags
-    JCC_1 %bb.3, 4, implicit $eflags
-    JMP_1 %bb.1
-
-  bb.1.bb1:
-    %6:gr64 = MOV32ri64 1
-    $rax = COPY %6
-    RET 0, $rax
-
-  bb.2.bb2:
-    %5:gr64 = MOV32ri64 2
-    $rax = COPY %5
-    RET 0, $rax
-
-  bb.3.bb3:
-    %4:gr64 = MOV32ri64 3
-    $rax = COPY %4
-    RET 0, $rax
-
-...
-)";
-
-  ASSERT_TRUE(parseMIR(MIRString, "f0"));
-
-  auto &MF =
-      FAM.getResult<MachineFunctionAnalysis>(*M->getFunction("f0")).getMF();
-
-  MachineDominatorTree DT(MF);
-  MachinePostDominatorTree PDT(MF);
-  MachineDomTreeUpdater DTU(DT, PDT,
-                            MachineDomTreeUpdater::UpdateStrategy::Eager);
-
-  ASSERT_TRUE(DTU.hasDomTree());
-  ASSERT_TRUE(DTU.hasPostDomTree());
-  ASSERT_TRUE(DTU.isEager());
-  ASSERT_FALSE(DTU.isLazy());
-  ASSERT_TRUE(DTU.getDomTree().verify());
-  ASSERT_TRUE(DTU.getPostDomTree().verify());
-  ASSERT_FALSE(DTU.hasPendingUpdates());
-
-  auto B = MF.begin();
-  [[maybe_unused]] auto BB0 = B;
-  auto BB1 = ++B;
-  auto BB2 = ++B;
-  [[maybe_unused]] auto BB3 = ++B;
-  auto BB4 = ++B;
-  EXPECT_EQ(BB1->succ_size(), 2u);
-  ASSERT_TRUE(DT.dominates(&*BB1, &*BB2));
-  ASSERT_TRUE(DT.dominates(&*BB1, &*BB4));
-  BB1->removeSuccessor(&*BB4);
-  DTU.deleteBB(&*BB4);
-  EXPECT_EQ(BB1->succ_size(), 1u);
-  ASSERT_TRUE(DT.dominates(&*BB1, &*BB2));
-  ASSERT_EQ(DT.getNode(&*BB4), nullptr);
-}
-
-TEST_F(MachineDomTreeUpdaterTest, LazyUpdateBasicOperations) {
-  StringRef MIRString = R"(
---- |
-  define i64 @f0(i64 %i, ptr %p) {
-  bb0:
-    store i64 %i, ptr %p, align 4
-    switch i64 %i, label %bb1 [
-      i64 1, label %bb2
-      i64 2, label %bb3
-    ]
-  bb1:                                              ; preds = %bb0
-    ret i64 1
-  bb2:                                              ; preds = %bb0
-    ret i64 2
-  bb3:                                              ; preds = %bb0
-    ret i64 3
-  }
-...
----
-name:            f0
-body:             |
-  bb.0.bb0:
-    successors: %bb.2, %bb.4
-    liveins: $rdi, $rsi
-
-    %1:gr32 = COPY $rsi
-    %0:gr64 = COPY $rdi
-    MOV64mr %1, 1, $noreg, 0, $noreg, %0 :: (store (s64) into %ir.p)
-    %2:gr64 = SUB64ri32 %0, 1, implicit-def $eflags
-    JCC_1 %bb.2, 4, implicit $eflags
-    JMP_1 %bb.4
-
-  bb.4.bb0:
-    successors: %bb.3, %bb.1
-
-    %3:gr64 = SUB64ri32 %0, 2, implicit-def $eflags
-    JCC_1 %bb.3, 4, implicit $eflags
-    JMP_1 %bb.1
-
-  bb.1.bb1:
-    %6:gr64 = MOV32ri64 1
-    $rax = COPY %6
-    RET 0, $rax
-
-  bb.2.bb2:
-    %5:gr64 = MOV32ri64 2
-    $rax = COPY %5
-    RET 0, $rax
-
-  bb.3.bb3:
-    %4:gr64 = MOV32ri64 3
-    $rax = COPY %4
-    RET 0, $rax
-
-...
-)";
-
-  ASSERT_TRUE(parseMIR(MIRString, "f0"));
-
-  auto &MF =
-      FAM.getResult<MachineFunctionAnalysis>(*M->getFunction("f0")).getMF();
-
-  MachineDominatorTree DT(MF);
-  MachinePostDominatorTree PDT(MF);
-  MachineDomTreeUpdater DTU(DT, PDT,
-                            MachineDomTreeUpdater::UpdateStrategy::Lazy);
-
-  ASSERT_TRUE(DTU.hasDomTree());
-  ASSERT_TRUE(DTU.hasPostDomTree());
-  ASSERT_FALSE(DTU.isEager());
-  ASSERT_TRUE(DTU.isLazy());
-  ASSERT_TRUE(DTU.getDomTree().verify());
-  ASSERT_TRUE(DTU.getPostDomTree().verify());
-  ASSERT_FALSE(DTU.hasPendingUpdates());
-
-  auto B = MF.begin();
-  [[maybe_unused]] auto BB0 = B;
-  auto BB1 = ++B;
-  auto BB2 = ++B;
-  [[maybe_unused]] auto BB3 = ++B;
-  auto BB4 = ++B;
-  EXPECT_EQ(BB1->succ_size(), 2u);
-  ASSERT_TRUE(DT.dominates(&*BB1, &*BB2));
-  ASSERT_TRUE(DT.dominates(&*BB1, &*BB4));
-  BB1->removeSuccessor(&*BB4);
-  DTU.deleteBB(&*BB4);
-  EXPECT_EQ(BB1->succ_size(), 1u);
-  ASSERT_TRUE(DT.dominates(&*BB1, &*BB2));
-  ASSERT_NE(DT.getNode(&*BB4), nullptr);
-  DTU.flush();
-  ASSERT_EQ(DT.getNode(&*BB4), nullptr);
-}


        


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