#13077: Worker/wrapper can break the let-app invariant -------------------------------------+------------------------------------- Reporter: simonpj | Owner: Type: bug | Status: closed Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Resolution: fixed | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: | stranal/should_compile/T13077, | T13077a Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by simonpj): * status: new => closed * testcase: => stranal/should_compile/T13077, T13077a * resolution: => fixed Comment: Fixed by {{{ commit 596dece7866006d699969f775fd97bd306aad85b Author: Simon Peyton Jones <simonpj@microsoft.com> Date: Fri Jan 13 08:56:53 2017 +0000 Record evaluated-ness on workers and wrappers Summary: This patch is a refinement of the original commit (which was reverted): commit 6b976eb89fe72827f226506d16d3721ba4e28bab Date: Fri Jan 13 08:56:53 2017 +0000 Record evaluated-ness on workers and wrappers In Trac #13027, comment:20, I noticed that wrappers created after demand analysis weren't recording the evaluated-ness of strict constructor arguments. In the ticket that led to a (debatable) Lint error but in general the more we know about evaluated-ness the better we can optimise. This commit adds that info * both in the worker (on args) * and in the wrapper (on CPR result patterns). See Note [Record evaluated-ness in worker/wrapper] in WwLib On the way I defined Id.setCaseBndrEvald, and used it to shorten the code in a few other places Then I added test T13077a to test the CPR aspect of this patch, but I found that Lint failed! Reason: simpleOptExpr was discarding evaluated-ness info on lambda binders because zapFragileIdInfo was discarding an Unfolding of (OtherCon _). But actually that's a robust unfolding; there is no need to discard it. To fix this: * zapFragileIdInfo only zaps fragile unfoldings * Replace isClosedUnfolding with isFragileUnfolding (the latter is just the negation of the former, but the nomenclature is more consistent). Better documentation too Note [Fragile unfoldings] * And Simplify.simplLamBndr can now look at isFragileUnfolding to decide whether to use the longer route of simplUnfolding. For some reason perf/compiler/T9233 improves in compile-time allocation by 10%. Hooray Nofib: essentially no change: -------------------------------------------------------------------------------- Program Size Allocs Runtime Elapsed TotalMem -------------------------------------------------------------------------------- cacheprof +0.0% -0.3% +0.9% +0.4% +0.0% -------------------------------------------------------------------------------- Min +0.0% -0.3% -2.4% -2.4% +0.0% Max +0.0% +0.0% +9.8% +11.4% +2.4% Geometric Mean +0.0% -0.0% +1.1% +1.0% +0.0% }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13077#comment:2> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler