Avoid dereferencing end() in collectInterferingVRegs() when there is no
interference.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122108 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/LiveIntervalUnion.cpp b/lib/CodeGen/LiveIntervalUnion.cpp
index 7ebe96f..cec6885 100644
--- a/lib/CodeGen/LiveIntervalUnion.cpp
+++ b/lib/CodeGen/LiveIntervalUnion.cpp
@@ -238,7 +238,7 @@
InterferenceResult IR = firstInterference();
LiveInterval::iterator VirtRegEnd = VirtReg->end();
LiveInterval *RecentInterferingVReg = NULL;
- while (IR.LiveUnionI.valid()) {
+ if (IR.VirtRegI != VirtRegEnd) while (IR.LiveUnionI.valid()) {
// Advance the union's iterator to reach an unseen interfering vreg.
do {
if (IR.LiveUnionI.value() == RecentInterferingVReg)