[BOLT] Use std::tie to implement operator< (NFC) (llvm#143560)

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

Author: kazutakahirata

bolt/include/bolt/Core/BinaryBasicBlock.h

@@ -52,9 +52,8 @@ class BinaryBasicBlock {
     uint64_t MispredictedCount; /// number of branches mispredicted
 
     bool operator<(const BinaryBranchInfo &Other) const {
-      return (Count < Other.Count) ||
-             (Count == Other.Count &&
-              MispredictedCount < Other.MispredictedCount);
+      return std::tie(Count, MispredictedCount) <
+             std::tie(Other.Count, Other.MispredictedCount);
     }
   };
 

bolt/include/bolt/Passes/PAuthGadgetScanner.h

@@ -77,9 +77,7 @@ struct MCInstInBFReference {
     return BF == RHS.BF && Offset == RHS.Offset;
   }
   bool operator<(const MCInstInBFReference &RHS) const {
-    if (BF != RHS.BF)
-      return BF < RHS.BF;
-    return Offset < RHS.Offset;
+    return std::tie(BF, Offset) < std::tie(RHS.BF, RHS.Offset);
   }
   operator MCInst &() const {
     assert(BF != nullptr);

bolt/lib/Profile/YAMLProfileWriter.cpp

@@ -303,9 +303,8 @@ YAMLProfileWriter::convert(const BinaryFunction &BF, bool UseDFS,
       }
       // Sort targets in a similar way to getBranchData, see Location::operator<
       llvm::sort(CSTargets, [](const auto &RHS, const auto &LHS) {
-        if (RHS.first != LHS.first)
-          return RHS.first < LHS.first;
-        return RHS.second.Offset < LHS.second.Offset;
+        return std::tie(RHS.first, RHS.second.Offset) <
+               std::tie(LHS.first, LHS.second.Offset);
       });
       for (auto &KV : CSTargets)
         YamlBB.CallSites.push_back(KV.second);