Index: lib/Target/AMDGPU/GCNSchedStrategy.cpp
===================================================================
--- lib/Target/AMDGPU/GCNSchedStrategy.cpp
+++ lib/Target/AMDGPU/GCNSchedStrategy.cpp
@@ -350,6 +350,9 @@
       BB->insert(RegionEnd, MI);
       if (LIS) {
         LIS->handleMove(*MI, true);
+        // Reset read-undef flags and update them later.
+        for (auto &Def : MI->defs())
+          Def.setIsUndef(false);
         RegisterOperands RegOpers;
         RegOpers.collect(*MI, *TRI, MRI, ShouldTrackLaneMasks, false);
         if (ShouldTrackLaneMasks) {