#14068: Loopification using join points -------------------------------------+------------------------------------- Reporter: nomeata | Owner: nomeata Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Resolution: | Keywords: JoinPoints Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: #13966 #14067 | Differential Rev(s): Phab:D3811 #14827 | Wiki Page: | -------------------------------------+------------------------------------- Comment (by simonpj):
We get this code for drop, which does not satisfy the conditions for SpecConstr; in particular, drop is not recursive (SpecConstr only creates specializations for recursive functions):
And rightly so! The new code for `drop` look splendid. The first iteration unboxes the boxed parameter `n`, and then the `joinrec` is a tight inner loop that races down the list; it's pretty much identical to the `$sdrop` we got before. So why is this worse than the previous version? It should be easy enough for me to repro this even without your loopification patch, by manually writing the post-loopification code. If you can post that code here I'll be in a better position to help. Thanks! -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14068#comment:35 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler