[Utils] splitBlockBefore() always operates on DomTreeUpdater, so take it, not DomTree

Even though not all it's users operate on DomTreeUpdater,
it itself internally operates on DomTreeUpdater,
so it must mean everything is fine with that,
so just do that globally.

1 files changed, 15 insertions, 13 deletions

diff --git a/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp b/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp
index bfad88f..f89a1fa 100644
--- a/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp
+++ b/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp
@@ -546,8 +546,10 @@ BasicBlock *llvm::SplitBlock(BasicBlock *Old, Instruction *SplitPt,
                              DominatorTree *DT, LoopInfo *LI,
                              MemorySSAUpdater *MSSAU, const Twine &BBName,
                              bool Before) {
-  if (Before)
-    return splitBlockBefore(Old, SplitPt, DT, LI, MSSAU, BBName);
+  if (Before) {
+    DomTreeUpdater DTU(DT, DomTreeUpdater::UpdateStrategy::Lazy);
+    return splitBlockBefore(Old, SplitPt, &DTU, LI, MSSAU, BBName);
+  }
   BasicBlock::iterator SplitIt = SplitPt->getIterator();
   while (isa<PHINode>(SplitIt) || SplitIt->isEHPad())
     ++SplitIt;
@@ -580,7 +582,7 @@ BasicBlock *llvm::SplitBlock(BasicBlock *Old, Instruction *SplitPt,
 }
 
 BasicBlock *llvm::splitBlockBefore(BasicBlock *Old, Instruction *SplitPt,
-                                   DominatorTree *DT, LoopInfo *LI,
+                                   DomTreeUpdater *DTU, LoopInfo *LI,
                                    MemorySSAUpdater *MSSAU,
                                    const Twine &BBName) {
 
@@ -598,25 +600,25 @@ BasicBlock *llvm::splitBlockBefore(BasicBlock *Old, Instruction *SplitPt,
     if (Loop *L = LI->getLoopFor(Old))
       L->addBasicBlockToLoop(New, *LI);
 
-  if (DT) {
-    DomTreeUpdater DTU(DT, DomTreeUpdater::UpdateStrategy::Lazy);
+  if (DTU) {
     SmallVector<DominatorTree::UpdateType, 8> DTUpdates;
     // New dominates Old. The predecessor nodes of the Old node dominate
     // New node.
+    SmallSetVector<BasicBlock *, 8> UniquePredecessorsOfOld(pred_begin(New),
+                                                            pred_end(New));
     DTUpdates.push_back({DominatorTree::Insert, New, Old});
-    for (BasicBlock *Pred : predecessors(New))
-      if (DT->getNode(Pred)) {
-        DTUpdates.push_back({DominatorTree::Insert, Pred, New});
-        DTUpdates.push_back({DominatorTree::Delete, Pred, Old});
-      }
+    DTUpdates.reserve(DTUpdates.size() + 2 * UniquePredecessorsOfOld.size());
+    for (BasicBlock *UniquePredecessorOfOld : UniquePredecessorsOfOld) {
+      DTUpdates.push_back({DominatorTree::Insert, UniquePredecessorOfOld, New});
+      DTUpdates.push_back({DominatorTree::Delete, UniquePredecessorOfOld, Old});
+    }
 
-    DTU.applyUpdates(DTUpdates);
-    DTU.flush();
+    DTU->applyUpdates(DTUpdates);
 
     // Move MemoryAccesses still tracked in Old, but part of New now.
     // Update accesses in successor blocks accordingly.
     if (MSSAU) {
-      MSSAU->applyUpdates(DTUpdates, *DT);
+      MSSAU->applyUpdates(DTUpdates, DTU->getDomTree());
       if (VerifyMemorySSA)
         MSSAU->getMemorySSA()->verifyMemorySSA();
     }