(Simon Marlow, can you help?) I don't understand how breakpoints work. Why do you say "we are clearly trying to float past a breakpoint"? Why is it so clear? Why is it wrong to float a lazy thunk out of a breakpoint? The float-out pass really doesn't have anywhere else where we say "you really can't float anything out of this subexpression, not even top-level constant expressions". Simon | -----Original Message----- | From: ghc-devs [mailto:ghc-devs-bounces@haskell.org] On Behalf Of Peter | Wortmann | Sent: 04 February 2015 17:24 | To: ghc-devs@haskell.org | Subject: Re: [GHC] #10052: Panic (something to do with floatExpr?) | | | | We are clearly trying to float past a breakpoint here, which is simply | impossible. Pretty sure this would have been a panic before my changes | too (it would have tried to "mkNoCount" the breakpoint). Guess I was | wrong reading a "breakpoints don't appear here" invariant out of that... | | The quick fix would be to drop all floats in-place: | | -- scoped, counting and unsplittable, can't be floated through | | otherwise | = floatBody tOP_LEVEL expr | | This fixes the panic, but is a bit awkward. Probably better to change | SetLevels? Not a piece of code I'm very familiar with... | | Greetings, | Peter | | On 04/02/2015 13:31, Simon Peyton Jones wrote: | > Peter: | > | > Here's a bad crash, due to you. (Doing this by email because I'm | offline.) | > | > The (Tick t e) case of FloatOut.floatExpr is incomplete. It simply | panics in some cases. | > | > Could you fix this please? Either that case shouldn't happen, in which | case Core Lint should check for it, and whoever is generating it should | be fixed. Or it should happen, in which case floatExpr should do the | right thing. | > | > Could you leave a Note to explain what is happening in the floatExpr | (Tick ...) cases? | > | > Thanks | > | > Simon | > | > | -----Original Message----- | > | From: ghc-tickets [mailto:ghc-tickets-bounces@haskell.org] On Behalf | Of | > | GHC | > | Sent: 31 January 2015 17:38 | > | Cc: ghc-tickets@haskell.org | > | Subject: [GHC] #10052: Panic (something to do with floatExpr?) | > | | > | #10052: Panic (something to do with floatExpr?) | > | -------------------------------------+------------------------------- | ---- | > | -- | > | Reporter: edsko | Owner: | > | Type: bug | Status: new | > | Priority: normal | Milestone: | > | Component: Compiler | Version: 7.10.1-rc2 | > | Keywords: | Operating System: | > | Unknown/Multiple | > | Architecture: | Type of failure: | None/Unknown | > | Unknown/Multiple | Blocked By: | > | Test Case: | Related Tickets: | > | Blocking: | | > | Differential Revisions: | | > | -------------------------------------+------------------------------- | ---- | > | -- | > | Loading | > | | > | {{{ | > | main = let (x :: String) = "hello" in putStrLn x | > | }}} | > | | > | using a very simple driver for the GHC API (see T145.hs) causes a | ghc | > | panic: | > | | > | {{{ | > | [1 of 1] Compiling Main ( T145-input.hs, interpreted ) | > | T145: T145: panic! (the 'impossible' happened) | > | (GHC version 7.10.0.20150128 for x86_64-apple-darwin): | > | floatExpr tick | > | <<details unavailable>> | > | | > | Please report this as a GHC bug: | http://www.haskell.org/ghc/reportabug | > | }}} | > | | > | This panic is arising in our test case for #8333, so it may be | related | > | to | > | that bug. | > | | > | -- | > | Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10052 | > | GHC http://www.haskell.org/ghc/ | > | The Glasgow Haskell Compiler | > | _______________________________________________ | > | ghc-tickets mailing list | > | ghc-tickets@haskell.org | > | http://www.haskell.org/mailman/listinfo/ghc-tickets | > | | _______________________________________________ | ghc-devs mailing list | ghc-devs@haskell.org | http://www.haskell.org/mailman/listinfo/ghc-devs