*  Emitting try-catch is easy, emitting try-catch-finally not quite so.

https://github.com/scala/scala3/blob/6bf4483932b37415bf2d1e6753eb26e3cc9f7986/compiler/src/dotty/tools/backend/jvm/BCodeSyncAndTry.scala#L119-L124

Current code generator for try-finally works but is quite primitive - if thefinally block exists then we adjust every path in which control flow can exit thetry.expr or any of thetry.catch handlers in such a way for each of them we emit a finally block before continuing execution.
Becouse every input callsite of the finalizer may have a different destination implementing correct control flow is not trivial. Previously we duplicated the finalizer body for each of the control flows, that means that code of finalizer block is repeated at least2 + CatchHandlerCount + EarlyReturnsCount times (we always emitted at least twice - for happy patch and for uncought exception path

The new approach takes advantage of the enumerating inputs to create tableswitch that would control where to resume execution (refered as trampolines). Unfortunetlly we cannot pass values directly becouse LLVM would crash - it cannot confirm that saved throwables/result values are always initialized. To workaround this problem we need to introduce a temporary variable that could stash results/throwables when we suspend execution to run finalizer.

What's important is fact that constructs liketry { return 1 } finally {try () finally return 2} can be expressed in Scala (always yielding2) and needs to be supported. In case of explicit early return from method we need to introduce additional variables to stash results - these would always have the same type as method, and might use different type then type of try block expression. Becouse some paths can be never reachable these might be (correctly) removed after dead-code analysis. We need to ensure that removed branches would not infer with the reachable execution path. For this reason and for optimization reasons we create a single variable for early return and throwable instance for all nestedtry blocks.

Benchmarks: TODO
Size gains: In case of Java standard library (javalib_3) the jar is smaller by ~15kB (~0.25% improvement)