[llvm] Revert "[VPlan] Remove unnecessary DomTreeUpdater flush (NFC)." (PR #144758)

[Arthur Eubanks via llvm-commits]

https://github.com/aeubanks created https://github.com/llvm/llvm-project/pull/144758

This reverts commit 2e337349f436d75af112c081df5ec683871cbcc8.

Causes breakages internally, will post reproducer later.

>From 2157f6b595d78679bc727ddc0a901bc0e0a4390a Mon Sep 17 00:00:00 2001
From: Arthur Eubanks <aeubanks at google.com>
Date: Wed, 18 Jun 2025 17:24:37 +0000
Subject: [PATCH] Revert "[VPlan] Remove unnecessary DomTreeUpdater flush
 (NFC)."

This reverts commit 2e337349f436d75af112c081df5ec683871cbcc8.

Causes breakages internally, will post reproducer later.
---
 llvm/lib/Transforms/Vectorize/VPlan.cpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/llvm/lib/Transforms/Vectorize/VPlan.cpp b/llvm/lib/Transforms/Vectorize/VPlan.cpp
index 4332332ef5cc3..773a5a4a829c7 100644
--- a/llvm/lib/Transforms/Vectorize/VPlan.cpp
+++ b/llvm/lib/Transforms/Vectorize/VPlan.cpp
@@ -1015,6 +1015,8 @@ void VPlan::execute(VPTransformState *State) {
   for (VPBlockBase *Block : RPOT)
     Block->execute(State);
 
+  State->CFG.DTU.flush();
+
   VPBasicBlock *Header = vputils::getFirstLoopHeader(*this, State->VPDT);
   if (!Header)
     return;