Handle <undef> flag in machine code verifier.

Use of an <undef> register is treated like an <imp-use>. It is not an error to use a dead <undef> register.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@77890 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/CodeGen/MachineVerifier.cpp b/lib/CodeGen/MachineVerifier.cpp
index a13d39e868098a9f7c2192d4aaf8f118b74b3a1a..59864fb3a46c793f81498fce875aae54daa5d278 100644 (file)
--- a/lib/CodeGen/MachineVerifier.cpp
+++ b/lib/CodeGen/MachineVerifier.cpp
@@ -365,7 +365,8 @@ MachineVerifier::visitMachineOperand(const MachineOperand *MO, unsigned MONum)
           addRegWithSubRegs(regsKilled, Reg);
       }
       // Explicit use of a dead register.
-      if (!MO->isImplicit() && !regsLive.count(Reg)) {
+      // A register use marked <undef> is OK.
+      if (!MO->isImplicit() && !MO->isUndef() && !regsLive.count(Reg)) {
         if (TargetRegisterInfo::isPhysicalRegister(Reg)) {
           // Reserved registers may be used even when 'dead'.
           if (!isReserved(Reg))