RegisterPressure: Add operators to RegisterMaskPair

[axeldavy]

Summary

Add operators and a new constructor to RegisterMaskPair.
This makes it handier and enables to use set and maps with
the structure.

[rampitec]

include/llvm/CodeGen/RegisterPressure.h

45

That is undesirable to have a constructor which does not initialize fields.

[rampitec]

LGTM

include/llvm/CodeGen/RegisterPressure.h

 class RegisterClassInfo;
 
 struct RegisterMaskPair {
   unsigned RegUnit; ///< Virtual register or register unit.
   LaneBitmask LaneMask;
 
   RegisterMaskPair(unsigned RegUnit, LaneBitmask LaneMask)
       : RegUnit(RegUnit), LaneMask(LaneMask) {}
+
+  bool operator==(const RegisterMaskPair &RP) const {
+    return RegUnit == RP.RegUnit && LaneMask == RP.LaneMask;
+  }
+
+  bool operator<(const RegisterMaskPair &RP) const {
+    return RegUnit < RP.RegUnit ||
+      (RegUnit == RP.RegUnit && LaneMask < RP.LaneMask);
+  }
 };
 
 /// Base class for register pressure results.
 struct RegisterPressure {
   /// Map of max reg pressure indexed by pressure set ID, not class ID.
   std::vector<unsigned> MaxSetPressure;
 
   /// List of live in virtual registers or physical register units.