[llvm] [BranchFolding] Add an option to tail merge only bbs without successors (PR #101969)

[Matt Arsenault via llvm-commits]

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@@ -85,6 +85,11 @@ TailMergeSize("tail-merge-size",
               cl::desc("Min number of instructions to consider tail merging"),
               cl::init(3), cl::Hidden);
 
+static cl::opt<bool> TailMergeOnlyBBsWithoutSucc(
+    "tail-merge-only-bbs-without-succ",
+    cl::desc("Tail merge only basic blocks without successors"),
+    cl::init(false), cl::Hidden);
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arsenm wrote:

What is the point of the flag? Generally cl::opt should only be for test/debug, but I don't see how that is useful here.  If a target wants this behavior, it should be a target hook 

https://github.com/llvm/llvm-project/pull/101969