1 files changed, 15 insertions, 3 deletions
diff --git a/llvm/lib/Target/X86/X86FrameLowering.cpp b/llvm/lib/Target/X86/X86FrameLowering.cpp
index ab219f680ba..10a15e1a375 100644
--- a/llvm/lib/Target/X86/X86FrameLowering.cpp
+++ b/llvm/lib/Target/X86/X86FrameLowering.cpp
@@ -1893,17 +1893,29 @@ bool X86FrameLowering::spillCalleeSavedRegisters(
     if (!X86::GR64RegClass.contains(Reg) && !X86::GR32RegClass.contains(Reg))
       continue;
 
-    bool isLiveIn = MF.getRegInfo().isLiveIn(Reg);
+    const MachineRegisterInfo &MRI = MF.getRegInfo();
+    bool isLiveIn = MRI.isLiveIn(Reg);
     if (!isLiveIn)
       MBB.addLiveIn(Reg);
 
+    // Decide whether we can add a kill flag to the use.
+    bool CanKill = !isLiveIn;
+    // Check if any subregister is live-in
+    if (CanKill) {
+      for (MCRegAliasIterator AReg(Reg, TRI, false); AReg.isValid(); ++AReg) {
+        if (MRI.isLiveIn(*AReg)) {
+          CanKill = false;
+          break;
+        }
+      }
+    }
+
     // Do not set a kill flag on values that are also marked as live-in. This
     // happens with the @llvm-returnaddress intrinsic and with arguments
     // passed in callee saved registers.
     // Omitting the kill flags is conservatively correct even if the live-in
     // is not used after all.
-    bool isKill = !isLiveIn;
-    BuildMI(MBB, MI, DL, TII.get(Opc)).addReg(Reg, getKillRegState(isKill))
+    BuildMI(MBB, MI, DL, TII.get(Opc)).addReg(Reg, getKillRegState(CanKill))
       .setMIFlag(MachineInstr::FrameSetup);
   }