#12877: Constant propagation with basic unboxed arithmetic instructions -------------------------------------+------------------------------------- Reporter: hsyl20 | Owner: hsyl20 Type: feature request | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by simonpj): Interesting. I'm all for it. A good place to look is `SimplUtils.mkCase`. One thing it does ("Merge Nested Cases") is very similar to what you have. GHC does this: {{{ case x of A -> ea DEFAULT -> case x of B -> eb C -> ec ===> case x of A -> ea B -> eb C -> ec }}} But as you point out, if you just do your second transformation (after "if I'm not mistaken...") then the ''existing'' case-merging stuff will do the rest. And I think you might be able do to your second transformation just by adding a case to `SimplUtils.mkCase`. Yell if you need help. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12877#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler