[llvm] [LoopPeel] Fix branch weights' effect on block frequencies (PR #128785)

[Matt Arsenault via llvm-commits]

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@@ -7866,6 +7866,17 @@ The attributes in this metadata is added to all followup loops of the
 loop distribution pass. See
 :ref:`Transformation Metadata <transformation-metadata>` for details.
 
+'``llvm.loop.estimated_trip_count``' Metadata
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
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arsenm wrote:

Should explain where it should be attached. What if it's not placed on an arbitrary terminator that isn't a loop backed? 

https://github.com/llvm/llvm-project/pull/128785