Don't tamper with <undef> operands in MachineInstr::addRegisterKilled.

For an undef operand, MO.getReg() is meaningless and we should not use it.
Undef operands should be skipped entirely.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@78095 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/CodeGen/MachineInstr.cpp b/lib/CodeGen/MachineInstr.cpp
index c29a6e339e043cb7f0a7040cf176a555d9cba532..dd2fef7ff0015db1fad32333ae7fec4288d2e94b 100644 (file)
--- a/lib/CodeGen/MachineInstr.cpp
+++ b/lib/CodeGen/MachineInstr.cpp
@@ -1030,7 +1030,7 @@ bool MachineInstr::addRegisterKilled(unsigned IncomingReg,
   SmallVector<unsigned,4> DeadOps;
   for (unsigned i = 0, e = getNumOperands(); i != e; ++i) {
     MachineOperand &MO = getOperand(i);
-    if (!MO.isReg() || !MO.isUse())
+    if (!MO.isReg() || !MO.isUse() || MO.isUndef())
       continue;
     unsigned Reg = MO.getReg();
     if (!Reg)
@@ -1041,8 +1041,6 @@ bool MachineInstr::addRegisterKilled(unsigned IncomingReg,
         if (MO.isKill())
           // The register is already marked kill.
           return true;
-        // This operand can no longer be undef since Reg is live-in.
-        MO.setIsUndef(false);
         if (isPhysReg && isRegTiedToDefOperand(i))
           // Two-address uses of physregs must not be marked kill.
           return true;