From 7ed9683f7d0b93d524028a9ad2b954a6d0be8e19 Mon Sep 17 00:00:00 2001
From: Gerolf Hoflehner <ghoflehner@apple.com>
Date: Thu, 10 Jan 2019 21:53:13 +0000
Subject: [PATCH] [MachineCombiner][NFC] Prevent dereferencing past-the-end
 object in an MRI container

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@350896 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/MachineCombiner.cpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/lib/CodeGen/MachineCombiner.cpp b/lib/CodeGen/MachineCombiner.cpp
index 0c6efff7bb4..f51b482e20e 100644
--- a/lib/CodeGen/MachineCombiner.cpp
+++ b/lib/CodeGen/MachineCombiner.cpp
@@ -231,6 +231,8 @@ unsigned MachineCombiner::getLatency(MachineInstr *Root, MachineInstr *NewRoot,
     // Get the first instruction that uses MO
     MachineRegisterInfo::reg_iterator RI = MRI->reg_begin(MO.getReg());
     RI++;
+    if (RI == MRI->reg_end())
+      continue;
     MachineInstr *UseMO = RI->getParent();
     unsigned LatencyOp = 0;
     if (UseMO && BlockTrace.isDepInTrace(*Root, *UseMO)) {
-- 
2.50.1