[GHC] #11064: Call Arity has the trivial application case wrong
#11064: Call Arity has the trivial application case wrong -------------------------------------+------------------------------------- Reporter: nomeata | Owner: nomeata Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.2 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- In `e x`, the result of `x` is not shared in contrast to `e (f x)`, where CorePrep will turn it into `let y = f x in e x`. So in {{{ let f = ... in e (f x) }}} we know that f is called at most once, but in {{{ let f = ... in e f }}} we do not know that. Previously Call Arity would assume that in `e x`, `x` is evaluated at most once. This rarely would make a difference (the argument `x` is analized with an incoming arity of 0, so no eta-expansion would be done anyways), but of course this should still be fixed. I just validated a patch and will push shortly. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11064> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler
#11064: Call Arity has the trivial application case wrong -------------------------------------+------------------------------------- Reporter: nomeata | Owner: nomeata Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.2 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 Joachim Breitner <mail@…>): In [changeset:"a58eeb7febd67c93dab82de7049ef1dcdecd34e9/ghc" a58eeb7/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="a58eeb7febd67c93dab82de7049ef1dcdecd34e9" Call Arity: In "e x", the result of "x" is not shared in contrast to "e (f x)", where CorePrep will turn it into "let y = f x in e x". So in let f = ... in e (f x) we know that f is called at most once, but in let f = ... in e f we do not know that. Previously Call Arity would assume that in "e x", "x" is evaluated at most once. This rarely would make a difference (the argument "x" is analized with an incoming arity of 0, so no eta-expansion would be done anyways), but of course this should still be fixed. This fixes #11064. Note the corresponding code dmdTransformThunkDmd in DmdAnal. }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11064#comment:1> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler
#11064: Call Arity has the trivial application case wrong -------------------------------------+------------------------------------- Reporter: nomeata | Owner: nomeata Type: bug | Status: merge Priority: normal | Milestone: Component: Compiler | Version: 7.10.2 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: | -------------------------------------+------------------------------------- Changes (by nomeata): * status: new => merge Comment: Pushed to master. I’d like to see this in 7.10.3, if possible. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11064#comment:2> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler
#11064: Call Arity has the trivial application case wrong -------------------------------------+------------------------------------- Reporter: nomeata | Owner: nomeata Type: bug | Status: merge Priority: normal | Milestone: 7.10.3 Component: Compiler | Version: 7.10.2 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: | -------------------------------------+------------------------------------- Changes (by nomeata): * milestone: => 7.10.3 -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11064#comment:3> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler
#11064: Call Arity has the trivial application case wrong -------------------------------------+------------------------------------- Reporter: nomeata | Owner: nomeata Type: bug | Status: merge Priority: normal | Milestone: 7.10.3 Component: Compiler | Version: 7.10.2 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 bgamari): Is there some way we could formulate a test for this? -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11064#comment:4> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler
#11064: Call Arity has the trivial application case wrong -------------------------------------+------------------------------------- Reporter: nomeata | Owner: nomeata Type: bug | Status: closed Priority: normal | Milestone: 7.10.3 Component: Compiler | Version: 7.10.2 Resolution: fixed | 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: | -------------------------------------+------------------------------------- Changes (by bgamari): * status: merge => closed * resolution: => fixed -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11064#comment:5> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler
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