WASM NCG panic: destination label not in evaluation context

Summary

When compiling stringsearch, compilation fails with

<no location info>: error:
    panic! (the 'impossible' happened)
  GHC version 9.6.1:
	destination label not in evaluation context
  CallStack (from HasCallStack):
    panic, called at compiler/GHC/Wasm/ControlFlow/FromCmm.hs:303:17 in ghc:GHC.Wasm.ControlFlow.FromCmm

Steps to reproduce

Download Repro.hs (superficially minimised from stringsearch) and compile it with optimizations, e.g.

wget https://gist.githubusercontent.com/amesgen/bb0a4278b2b1d4a8eaef5c484769caf6/raw/b9c167204ec5068a3bee30c7d93ae697e34a64bc/Repro.hs
wasm32-wasi-ghc -O1 Repro.hs

It compiles fine with -O0.

Expected behavior

It should compile without panicking.

Environment

• GHC version used: 9.6.1; concretely: 9.6 and gmp flavour from ghc-wasm-meta, commit 3883ee24
• Operating System: NixOS
• System Architecture: x86_64-linux