From 7e7ad49c23867a5de8e15adfd946fdfa4ba68902 Mon Sep 17 00:00:00 2001
From: Chris Lattner <sabre@nondot.org>
Date: Thu, 27 Feb 2003 22:31:07 +0000
Subject: [PATCH] Add a new assertion to check that stuff is happening right
 Ironically the exit block modification code wasn't updating the exit block
 information itself.  Fix this.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@5659 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Transforms/Utils/LoopSimplify.cpp | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/lib/Transforms/Utils/LoopSimplify.cpp b/lib/Transforms/Utils/LoopSimplify.cpp
index dc9df6aa390..e40f1457ae4 100644
--- a/lib/Transforms/Utils/LoopSimplify.cpp
+++ b/lib/Transforms/Utils/LoopSimplify.cpp
@@ -95,6 +95,8 @@ bool Preheaders::ProcessLoop(Loop *L) {
   for (unsigned i = 0, e = L->getExitBlocks().size(); i != e; ++i)
     if (!DS.dominates(Header, L->getExitBlocks()[i])) {
       RewriteLoopExitBlock(L, L->getExitBlocks()[i]);
+      assert(DS.dominates(Header, L->getExitBlocks()[i]) &&
+             "RewriteLoopExitBlock failed?");
       NumInserted++;
       Changed = true;
     }
@@ -270,19 +272,22 @@ void Preheaders::RewriteLoopExitBlock(Loop *L, BasicBlock *Exit) {
   DominatorSet &DS = getAnalysis<DominatorSet>();
   assert(!DS.dominates(L->getHeader(), Exit) &&
          "Loop already dominates exit block??");
+  assert(std::find(L->getExitBlocks().begin(), L->getExitBlocks().end(), Exit)
+         != L->getExitBlocks().end() && "Not a current exit block!");
   
   std::vector<BasicBlock*> LoopBlocks;
   for (pred_iterator I = pred_begin(Exit), E = pred_end(Exit); I != E; ++I)
     if (L->contains(*I))
       LoopBlocks.push_back(*I);
 
-  BasicBlock *NewBB =
-    SplitBlockPredecessors(Exit, ".loopexit", LoopBlocks);
-  
+  assert(!LoopBlocks.empty() && "No edges coming in from outside the loop?");
+  BasicBlock *NewBB = SplitBlockPredecessors(Exit, ".loopexit", LoopBlocks);
+
   // Update Loop Information - we know that the new block will be in the parent
   // loop of L.
   if (Loop *Parent = L->getParentLoop())
     Parent->addBasicBlockToLoop(NewBB, getAnalysis<LoopInfo>());
+  L->changeExitBlock(Exit, NewBB);   // Update exit block information
 
   // Update dominator information...  The blocks that dominate NewBB are the
   // intersection of the dominators of predecessors, plus the block itself.