Re: [GHC] #14338: Simplifier fails with "Simplifier ticks exhausted"

#14338: Simplifier fails with "Simplifier ticks exhausted" -------------------------------------+------------------------------------- Reporter: dredozubov | Owner: bgamari Type: bug | Status: new Priority: high | Milestone: 8.4.1 Component: Compiler | Version: 8.2.1 Resolution: | Keywords: Operating System: Linux | Architecture: x86_64 Type of failure: Compile-time | (amd64) crash or panic | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by Simon Peyton Jones ): In [changeset:"954cbc7c106a20639960f55ebb85c5c972652d41/ghc" 954cbc7c/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="954cbc7c106a20639960f55ebb85c5c972652d41" Drop dead Given bindings in setImplicationStatus Trac #13032 pointed out that we sometimes generate unused bindings for Givens, and (worse still) we can't always discard them later (we don't drop a case binding unless we can prove that the scrutinee is non-bottom. It looks as if this may be a major reason for the performace problems in #14338 (see comment:29). This patch fixes the problem at source, by pruning away all the dead Givens. See Note [Delete dead Given evidence bindings] Remarkably, compiler allocation falls by 23% in perf/compiler/T12227! I have not confirmed whether this change actualy helps with }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14338#comment:30 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler