[llvm] [Bolt] Teach bolt about no-return functions (PR #115616)

[Anatoly Trosinenko via llvm-commits]

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@@ -272,6 +272,10 @@ class BinaryContext {
   /// DWARF line info for CUs.
   std::map<unsigned, DwarfLineTable> DwarfLineTablesCUMap;
 
+  /// Container to cache results about functions that their paths lead to
+  /// a no-return function.
+  std::unordered_map<BinaryFunction *, bool> CallsNoReturnFunction;
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atrosinenko wrote:

Hmm, it looks like LLVM Programmer's Manual [advises against](https://llvm.org/docs/ProgrammersManual.html#other-map-like-container-options) the usage of `std::unordered_map`, though there are several tens of occurrences even under `llvm/lib`. The same in `DiscoverNoReturnPass.h` below.

https://github.com/llvm/llvm-project/pull/115616