[llvm] [WebAssembly] Add unreachable before catch destinations (PR #123915)

[Heejin Ahn via llvm-commits]

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@@ -78,7 +78,8 @@ body: |
     EH_LABEL <mcsymbol .Ltmp2>
     CATCHRET %bb.2, %bb.1, implicit-def dead $arguments
 
-  ; CHECK: bb.2
+  ; This BB should remain (it will be renumbered to bb.1)
+  ; CHECK: bb.1
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aheejin wrote:

This renumbering happened because now we run `recalculateScopeTops` every time when EH is used. We used to run it only when unwind mismatches existed. Now we run it every time because adding `unreachable` after `end_try_table` requires splitting BBs and CFG changes.

https://github.com/llvm/llvm-project/pull/123915