#10676: silly assembly for comparing the result of comparisons that return Int# against 0# -------------------------------------+------------------------------------- Reporter: rwbarton | Owner: Type: bug | Status: closed Priority: normal | Milestone: Component: Compiler | Version: 7.10.1 (CodeGen) | Resolution: duplicate | Keywords: Operating System: Unknown/Multiple | Architecture: x86_64 Type of failure: Runtime | (amd64) performance bug | Test Case: Blocked By: | Blocking: Related Tickets: #8326, #8327 | Differential Revisions: -------------------------------------+------------------------------------- Comment (by simonpj): Wait! I believe that you are saying that {{{ case na# ==# nb# of 0# -> e1 _ -> e2 }}} generates much worse code than {{{ case isTrue# (na# ==# nb#) of False -> e1 True -> e2 }}} even though the former appears more primitive. This is all very odd and either deserves to be fixed, or at least documented somewhere prominent! Where would be a good place to document it? Perhaps with the primops for `(==)#`, `(>=)#`, etc? Or with `isTrue#`? And we need a ticket to say "let's fix this". Speaking of which do you know why it behaves so badly? Just changing the code is leaving land-mines for future generations :-). Simon -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10676#comment:7 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler