[llvm] Avoid BlockFrequency overflow problems (PR #66280)

[Matthias Braun via llvm-commits]

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@@ -76,6 +78,12 @@ class BlockFrequency {
     return NewFreq;
   }
 
+  /// Multiplies frequency with `Factor` and stores the result into `Result`.
+  /// Returns `true` if an overflow occured. Overflows are common and should be
+  /// checked by all callers.
+  bool mul(uint64_t Factor,
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MatzeB wrote:

Somehow I know `__attribute__((...))`s better than C++17 :) Will switch, great to see this feature in the standard!

https://github.com/llvm/llvm-project/pull/66280