1 files changed, 18 insertions, 2 deletions
diff --git a/llvm/lib/CodeGen/RegAllocGreedy.cpp b/llvm/lib/CodeGen/RegAllocGreedy.cpp
index 8e6cf3e..5638f98 100644
--- a/llvm/lib/CodeGen/RegAllocGreedy.cpp
+++ b/llvm/lib/CodeGen/RegAllocGreedy.cpp
@@ -1406,8 +1406,24 @@ bool RAGreedy::trySplitAroundHintReg(MCPhysReg Hint,
       continue;
 
     // Check if VirtReg interferes with OtherReg after this COPY instruction.
-    if (!IsDef && VirtReg.liveAt(LIS->getInstructionIndex(Instr).getRegSlot()))
-      continue;
+    if (Opnd.readsReg()) {
+      SlotIndex Index = LIS->getInstructionIndex(Instr).getRegSlot();
+
+      if (SubReg) {
+        LaneBitmask Mask = TRI->getSubRegIndexLaneMask(SubReg);
+        if (IsDef)
+          Mask = ~Mask;
+
+        if (any_of(VirtReg.subranges(), [=](const LiveInterval::SubRange &S) {
+              return (S.LaneMask & Mask).any() && S.liveAt(Index);
+            })) {
+          continue;
+        }
+      } else {
+        if (VirtReg.liveAt(Index))
+          continue;
+      }
+    }
 
     MCRegister OtherPhysReg =
         OtherReg.isPhysical() ? OtherReg.asMCReg() : VRM->getPhys(OtherReg);