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

[Vladimir Radosavljevic 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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vladimirradosavljevic wrote:

> Can you use branch probabilities to decide which are not frequently executed?

I think it is feasible, but taking into account that here we can just use early return if option is passed, I would say it is not worth it to add complexity to this.

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