Properly deal with empty intervals when checking for interference.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121319 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/LiveIntervalUnion.cpp b/lib/CodeGen/LiveIntervalUnion.cpp
index bedf22b..4b9a2d3 100644
--- a/lib/CodeGen/LiveIntervalUnion.cpp
+++ b/lib/CodeGen/LiveIntervalUnion.cpp
@@ -111,9 +111,10 @@
// Assumes that segments are sorted by start position in both
// LiveInterval and LiveSegments.
void LiveIntervalUnion::Query::findIntersection(InterferenceResult &IR) const {
-
// Search until reaching the end of the LiveUnion segments.
LiveInterval::iterator VirtRegEnd = VirtReg->end();
+ if (IR.VirtRegI == VirtRegEnd)
+ return;
while (IR.LiveUnionI.valid()) {
// Slowly advance the live virtual reg iterator until we surpass the next
// segment in LiveUnion.