#14123: Figure out invariants surrounding ticks in Core -------------------------------------+------------------------------------- Reporter: bgamari | Owner: (none) Type: task | Status: new Priority: highest | Milestone: 8.4.1 Component: Compiler | Version: 8.2.1 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: | -------------------------------------+------------------------------------- Changes (by bgamari): * cc: simonpj, JaffaCake (added) Old description:

In the past we have had a number of issues stemming from ticks breaking various Core analyses in GHC,

* #13233: a tick separates a levity-polymorphic tycon (e.g. an unboxed tuple tycon) from its levity arguments, resulting in a `typePrimRep` panic. * ticket:8472#comment:22: a tick wraps a primitive string literal, causing `CoreToStg` to fail to notice it is a string resulting in a panic * #14122: Another literal string issue which I have yet to debug but seems very likely to be tick-related.

We have merged a stop-gap solution/hack (f5b275a239d2554c4da0b7621211642bf3b10650) to the `ghc-8.2` branch however need a more principled solution in the long-term (e.g. before 8.4). We will need to start by defining precisely where ticks are allowed and add appropriate logic to CoreLint to verify that this invariant is upheld.

New description: In the past we have had a number of issues stemming from ticks breaking various Core analyses in GHC, * #13233: a tick separates a levity-polymorphic tycon (e.g. an unboxed tuple tycon) from its levity arguments, resulting in a `typePrimRep` panic. * ticket:8472#comment:22: a tick wraps a primitive string literal, causing `CoreToStg` to fail to notice it is a string resulting in a panic * #14122: Another literal string issue which I have yet to debug but seems very likely to be tick-related. We have merged a stop-gap solution/hack (f5b275a239d2554c4da0b7621211642bf3b10650) to the `master` branch (present in GHC 8.2.1) however we will need a more principled solution in the long- term (e.g. before 8.4). We will need to start by defining precisely where ticks are allowed and add appropriate logic to `CoreLint` to verify that this invariant is upheld. -- -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14123#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#14123: Figure out invariants surrounding ticks in Core -------------------------------------+------------------------------------- Reporter: bgamari | Owner: (none) Type: task | Status: new Priority: highest | Milestone: 8.4.1 Component: Compiler | Version: 8.2.1 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 Ben Gamari ): In [changeset:"6e7c09d083358b07401cbecc36043be5dfe15f84/ghc" 6e7c09d/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="6e7c09d083358b07401cbecc36043be5dfe15f84" StgCmmMonad: Remove unnecessary use of unboxed tuples The simplifier can simplify this without any trouble. Moreover, the unboxed tuples cause bootstrapping issues due #14123. I also went ahead and inlined a few definitions into the Monad instance. Test Plan: Validate Reviewers: austin, simonmar Subscribers: rwbarton, thomie Differential Revision: https://phabricator.haskell.org/D4026 }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14123#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#14123: Figure out invariants surrounding ticks in Core -------------------------------------+------------------------------------- Reporter: bgamari | Owner: (none) Type: task | Status: new Priority: highest | Milestone: 8.4.1 Component: Compiler | Version: 8.2.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: #13233, #14122, | Differential Rev(s): #8472, #14406 | Wiki Page: | -------------------------------------+------------------------------------- Changes (by bgamari): * related: #13233, #142122, #8472, #14406 => #13233, #14122, #8472, #14406 -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14123#comment:5 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#14123: Figure out invariants surrounding ticks in Core -------------------------------------+------------------------------------- Reporter: bgamari | Owner: (none) Type: task | Status: new Priority: highest | Milestone: 8.4.1 Component: Compiler | Version: 8.2.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: #13233, #14122, | Differential Rev(s): #8472, #14406 | Wiki Page: | -------------------------------------+------------------------------------- Comment (by bgamari): Phab:D3925 is a differential that I was working on some time ago asserting that primitive strings aren't ticked. The fact that the assertion fails is a canary suggesting that something is amiss here. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14123#comment:7 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#14123: Figure out invariants surrounding ticks in Core -------------------------------------+------------------------------------- Reporter: bgamari | Owner: (none) Type: task | Status: new Priority: highest | Milestone: 8.6.1 Component: Compiler | Version: 8.2.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: #13233, #14122, | Differential Rev(s): #8472, #14406, #14779 | Wiki Page: | -------------------------------------+------------------------------------- Changes (by bgamari): * related: #13233, #14122, #8472, #14406 => #13233, #14122, #8472, #14406, #14779 Comment: Niteria has made some progress on this in #14779. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14123#comment:9 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#14123: Figure out invariants surrounding ticks in Core -------------------------------------+------------------------------------- Reporter: bgamari | Owner: (none) Type: task | Status: new Priority: highest | Milestone: 8.8.1 Component: Compiler | Version: 8.2.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: #13233, #14122, | Differential Rev(s): #8472, #14406, #14779 | Wiki Page: | -------------------------------------+------------------------------------- Changes (by bgamari): * milestone: 8.6.1 => 8.8.1 Comment: I suspect there is a bit more documentation that could be written in this area but the major bugs are sorted. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14123#comment:11 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler