[llvm] [BranchFolding] Remove dubious assert from operator< (PR #71639)

[Matt Arsenault via llvm-commits]

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@@ -485,13 +485,7 @@ BranchFolder::MergePotentialsElt::operator<(const MergePotentialsElt &o) const {
     return true;
   if (getBlock()->getNumber() > o.getBlock()->getNumber())
     return false;
-  // _GLIBCXX_DEBUG checks strict weak ordering, which involves comparing
-  // an object with itself.
-#ifndef _GLIBCXX_DEBUG
-  llvm_unreachable("Predecessor appears twice");
-#else
   return false;
-#endif
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arsenm wrote:

I don't really see the point of asserting this in the first place 

https://github.com/llvm/llvm-project/pull/71639