[llvm] [ThinLTO] Add tail call flag to call edges in summary (PR #74043)

[Snehasish Kumar via llvm-commits]

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@@ -68,21 +68,31 @@ struct CalleeInfo {
   // added to HotnessType enum.
   uint32_t Hotness : 3;
 
+  // True if at least one of the calls to the callee is a tail call.
+  bool HasTailCall : 1;
+
   /// The value stored in RelBlockFreq has to be interpreted as the digits of
   /// a scaled number with a scale of \p -ScaleShift.
-  uint32_t RelBlockFreq : 29;
+  static constexpr unsigned RelBlockFreqBits = 28;
+  uint32_t RelBlockFreq : RelBlockFreqBits;
   static constexpr int32_t ScaleShift = 8;
-  static constexpr uint64_t MaxRelBlockFreq = (1 << 29) - 1;
+  static constexpr uint64_t MaxRelBlockFreq = (1 << RelBlockFreqBits) - 1;
 
   CalleeInfo()
-      : Hotness(static_cast<uint32_t>(HotnessType::Unknown)), RelBlockFreq(0) {}
-  explicit CalleeInfo(HotnessType Hotness, uint64_t RelBF)
-      : Hotness(static_cast<uint32_t>(Hotness)), RelBlockFreq(RelBF) {}
+      : Hotness(static_cast<uint32_t>(HotnessType::Unknown)),
+        HasTailCall(false), RelBlockFreq(0) {}
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snehasish wrote:

Ah, we are not yet on c++20. Thanks for checking.

https://github.com/llvm/llvm-project/pull/74043