[llvm] Use std::tie to implement operator< (NFC) (llvm#143728)

std::tie facilitates lexicographical comparisons through std::tuple's
built-in operator<.

Author: kazutakahirata

llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldImpl.h

@@ -202,15 +202,9 @@ class RelocationValueRef {
            IsStubThumb == Other.IsStubThumb;
   }
   inline bool operator<(const RelocationValueRef &Other) const {
-    if (SectionID != Other.SectionID)
-      return SectionID < Other.SectionID;
-    if (Offset != Other.Offset)
-      return Offset < Other.Offset;
-    if (Addend != Other.Addend)
-      return Addend < Other.Addend;
-    if (IsStubThumb != Other.IsStubThumb)
-      return IsStubThumb < Other.IsStubThumb;
-    return SymbolName < Other.SymbolName;
+    return std::tie(SectionID, Offset, Addend, IsStubThumb, SymbolName) <
+           std::tie(Other.SectionID, Other.Offset, Other.Addend,
+                    Other.IsStubThumb, Other.SymbolName);
   }
 };
 

llvm/lib/Target/Hexagon/HexagonConstExtenders.cpp

@@ -253,7 +253,7 @@ namespace {
       bool operator!=(Register R) const { return !operator==(R); }
       bool operator<(Register R) const {
         // For std::map.
-        return Reg < R.Reg || (Reg == R.Reg && Sub < R.Sub);
+        return std::tie(Reg, Sub) < std::tie(R.Reg, R.Sub);
       }
       llvm::Register Reg;
       unsigned Sub = 0;
@@ -298,11 +298,7 @@ namespace {
         return !operator==(Ex);
       }
       bool operator<(const ExtExpr &Ex) const {
-        if (Rs != Ex.Rs)
-          return Rs < Ex.Rs;
-        if (S != Ex.S)
-          return S < Ex.S;
-        return !Neg && Ex.Neg;
+        return std::tie(Rs, S, Neg) < std::tie(Ex.Rs, Ex.S, Ex.Neg);
       }
     };