commit 7ed9683f7d0b93d524028a9ad2b954a6d0be8e19
author Gerolf Hoflehner <ghoflehner@apple.com> Thu Jan 10 21:53:13 2019 +0000
committer Gerolf Hoflehner <ghoflehner@apple.com> Thu Jan 10 21:53:13 2019 +0000
tree 5e2c9464ec2357ff1a21d07d2e0f901f3413c6dc
parent 3c10eaa3db0bc317e7df61e0022ac12132e038ba

[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

diff --git a/lib/CodeGen/MachineCombiner.cpp b/lib/CodeGen/MachineCombiner.cpp
index 0c6efff..f51b482 100644
--- a/lib/CodeGen/MachineCombiner.cpp
+++ b/lib/CodeGen/MachineCombiner.cpp
@@ -231,6 +231,8 @@
     // 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)) {