From 6382d2caddb98f30f556b43faa898ff675affaf7 Mon Sep 17 00:00:00 2001
From: Jakob Stoklund Olesen <stoklund@2pi.dk>
Date: Tue, 13 Jul 2010 19:56:28 +0000
Subject: [PATCH] Add an assertion to make PR7542 fail consistently.

LiveInterval::overlapsFrom dereferences end() if it is called on an empty
interval.

It would be reasonable to just return false - an empty interval doesn't overlap
anything, but I want to know who is doing it first.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@108264 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/LiveInterval.cpp | 1 +
 1 file changed, 1 insertion(+)

diff --git a/lib/CodeGen/LiveInterval.cpp b/lib/CodeGen/LiveInterval.cpp
index 9b057b0fec2..1b8509b9a15 100644
--- a/lib/CodeGen/LiveInterval.cpp
+++ b/lib/CodeGen/LiveInterval.cpp
@@ -119,6 +119,7 @@ bool LiveInterval::killedInRange(SlotIndex Start, SlotIndex End) const {
 //
 bool LiveInterval::overlapsFrom(const LiveInterval& other,
                                 const_iterator StartPos) const {
+  assert(!empty() && "empty interval");
   const_iterator i = begin();
   const_iterator ie = end();
   const_iterator j = StartPos;