[MachineInstrBundle] Update the comment for PhysRegInfo::DeadDef.

I missed read the comment when I commited r267621 and thought the
comment did not need update. Matthias kindly proved me wrong.
Fixing that.

llvm-svn: 267638

diff --git a/llvm/include/llvm/CodeGen/MachineInstrBundle.h b/llvm/include/llvm/CodeGen/MachineInstrBundle.h
index fd828d4..c0033a5 100644 (file)
--- a/llvm/include/llvm/CodeGen/MachineInstrBundle.h
+++ b/llvm/include/llvm/CodeGen/MachineInstrBundle.h
@@ -183,8 +183,10 @@ public:
     /// Reg or a super-register is read. The full register is read.
     bool FullyRead;
 
-    /// Reg is FullyDefined and all defs of reg or an overlapping register are
-    /// dead.
+    /// Either:
+    /// - Reg is FullyDefined and all defs of reg or an overlapping
+    ///   register are dead, or
+    /// - Reg is completely dead because "defined" by a clobber.
     bool DeadDef;
 
     /// Reg is Defined and all defs of reg or an overlapping register are