From 42eb7524ef3a994f184924e583871406cf5d1ed6 Mon Sep 17 00:00:00 2001
From: Chris Lattner <sabre@nondot.org>
Date: Fri, 20 May 2005 22:19:54 +0000
Subject: [PATCH] Fix Transforms/SimplifyCFG/switch-simplify-crash.ll

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@22158 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Transforms/Utils/SimplifyCFG.cpp | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/lib/Transforms/Utils/SimplifyCFG.cpp b/lib/Transforms/Utils/SimplifyCFG.cpp
index 15ea761f2ce..ad78506ad42 100644
--- a/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -1236,6 +1236,7 @@ bool llvm::SimplifyCFG(BasicBlock *BB) {
         } else if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) {
           for (unsigned i = 1, e = SI->getNumCases(); i != e; ++i)
             if (SI->getSuccessor(i) == BB) {
+              BB->removePredecessor(SI->getParent());
               SI->removeCase(i);
               --i; --e;
               Changed = true;
@@ -1263,6 +1264,12 @@ bool llvm::SimplifyCFG(BasicBlock *BB) {
               SI->setSuccessor(0, MaxBlock);
               Changed = true;
 
+              // If MaxBlock has phinodes in it, remove MaxPop-1 entries from
+              // it.
+              if (isa<PHINode>(MaxBlock->begin()))
+                for (unsigned i = 0; i != MaxPop-1; ++i)
+                  MaxBlock->removePredecessor(SI->getParent());
+
               for (unsigned i = 1, e = SI->getNumCases(); i != e; ++i)
                 if (SI->getSuccessor(i) == MaxBlock) {
                   SI->removeCase(i);