From 6acc9e6b7bc5cc5b45a69988b2805674da62a820 Mon Sep 17 00:00:00 2001
From: Devang Patel <dpatel@apple.com>
Date: Mon, 13 Aug 2007 21:59:17 +0000
Subject: [PATCH] If NewBB dominates DestBB then DestBB is not part of NewBB's
 dominance frontier.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@41051 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Transforms/Utils/BreakCriticalEdges.cpp | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/lib/Transforms/Utils/BreakCriticalEdges.cpp b/lib/Transforms/Utils/BreakCriticalEdges.cpp
index af9a114bbeb..e28d59d7c3a 100644
--- a/lib/Transforms/Utils/BreakCriticalEdges.cpp
+++ b/lib/Transforms/Utils/BreakCriticalEdges.cpp
@@ -227,8 +227,12 @@ bool llvm::SplitCriticalEdge(TerminatorInst *TI, unsigned SuccNum, Pass *P,
     DominanceFrontier::DomSetType NewDFSet;
     if (NewBBDominatesDestBB) {
       DominanceFrontier::iterator I = DF->find(DestBB);
-      if (I != DF->end())
+      if (I != DF->end()) {
         DF->addBasicBlock(NewBB, I->second);
+        // However NewBB's frontier does not include DestBB.
+        DominanceFrontier::iterator NF = DF->find(NewBB);
+        DF->removeFromFrontier(NF, DestBB);
+      }
       else
         DF->addBasicBlock(NewBB, DominanceFrontier::DomSetType());
     } else {