NCG: Fix a bug where we errounously removed a required jump instruction.
NCG: Fix a bug where we errounously removed a required jump instruction.
Add a new method to the Instruction class to check if we can eliminate a
jump in favour of fallthrough control flow.
Fixes #24507
I had considered changing the behaviour of jumpDestsOfInstruction but that seemed overly messy.
I had also tried (ab)using canShortcut for this but this also turned out to be messy and slightly nonsensically. For example a backend might not support shortcutting, but it should still support this far simplier method of eliminating some redundant jumps.