Extract LaneBitmask into a separate type

Specifically avoid implicit conversions from/to integral types to
avoid potential errors when changing the underlying type. For example,
a typical initialization of a "full" mask was "LaneMask = ~0u", which
would result in a value of 0x00000000FFFFFFFF if the type was extended
to uint64_t.

Differential Revision: https://reviews.llvm.org/D27454

llvm-svn: 289820
diff --git a/llvm/lib/CodeGen/MachinePipeliner.cpp b/llvm/lib/CodeGen/MachinePipeliner.cpp
index 23d7c60..c908681 100644
--- a/llvm/lib/CodeGen/MachinePipeliner.cpp
+++ b/llvm/lib/CodeGen/MachinePipeliner.cpp
@@ -1742,11 +1742,13 @@
         unsigned Reg = MO.getReg();
         if (TargetRegisterInfo::isVirtualRegister(Reg)) {
           if (!Uses.count(Reg))
-            LiveOutRegs.push_back(RegisterMaskPair(Reg, 0));
+            LiveOutRegs.push_back(RegisterMaskPair(Reg,
+                                                   LaneBitmask::getNone()));
         } else if (MRI.isAllocatable(Reg)) {
           for (MCRegUnitIterator Units(Reg, TRI); Units.isValid(); ++Units)
             if (!Uses.count(*Units))
-              LiveOutRegs.push_back(RegisterMaskPair(*Units, 0));
+              LiveOutRegs.push_back(RegisterMaskPair(*Units,
+                                                     LaneBitmask::getNone()));
         }
       }
   RPTracker.addLiveRegs(LiveOutRegs);