[llvm] [SimplifyCFG] Convert switch to cmp/select sequence (PR #82795)

[Matt Arsenault via llvm-commits]

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@@ -6166,6 +6166,279 @@ static bool trySwitchToSelect(SwitchInst *SI, IRBuilder<> &Builder,
   return true;
 }
 
+// The first field contains the value that the switch produces when a certain
+// case group is selected, and the second field is a vector containing the
+// cases composing the case group.
+using SwitchCaseResultVectorTy2 =
+    SmallVector<std::pair<Value *, SmallVector<Value *, 4>>, 2>;
+
+using PHINodeToCaseEntryValueMapTy = std::map<
+    llvm::PHINode *,
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arsenm wrote:

Don't need llvm:: 

https://github.com/llvm/llvm-project/pull/82795