#10528: compile time performance regression with OverloadedStrings and Text -------------------------------------+------------------------------------- Reporter: jakewheat | Owner: Type: bug | Status: merge Priority: high | Milestone: 7.10.3 Component: Compiler | Version: 7.10.2-rc2 Resolution: | Keywords: Operating System: Linux | Architecture: Type of failure: Compile-time | Unknown/Multiple performance bug | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Revisions: -------------------------------------+------------------------------------- Comment (by afarmer): Proposed patch that implements Option 3 in my list above... which I think is the best short term solution. {{{ diff --git a/compiler/simplCore/Simplify.hs b/compiler/simplCore/Simplify.hs index d816d3f..0e4ca50 100644 --- a/compiler/simplCore/Simplify.hs +++ b/compiler/simplCore/Simplify.hs @@ -38,7 +38,7 @@ import CoreArity --import PrimOp ( tagToEnumKey ) -- temporalily commented out. See #8326 import Rules ( mkSpecInfo, lookupRule, getRules ) import TysPrim ( voidPrimTy ) --, intPrimTy ) -- temporalily commented out. See #8326 -import BasicTypes ( TopLevelFlag(..), isTopLevel, RecFlag(..) ) +import BasicTypes ( TopLevelFlag(..), isTopLevel, RecFlag(..), Activation(..) ) import MonadUtils ( foldlM, mapAccumLM, liftIO ) import Maybes ( orElse ) --import Unique ( hasKey ) -- temporalily commented out. See #8326 @@ -2970,7 +2970,9 @@ simplRules env mb_new_nm rules , ru_act = act }) = do { (env, bndrs') <- simplBinders env bndrs ; let lhs_env = updMode updModeForRuleLHS env - rhs_env = updMode (updModeForStableUnfoldings act) env + rhs_env = case act of + NeverActive -> lhs_env + _ -> updMode (updModeForStableUnfoldings act) env ; args' <- mapM (simplExpr lhs_env) args ; rhs' <- simplExpr rhs_env rhs ; return (rule { ru_bndrs = bndrs' }}} Since NeverActive rules are not actually applied by GHC, not rewriting their RHSs shouldn't change anything for real libraries, while still offering HERMIT access to the original rule without the extra inlining/rule application. This patch also allows our test suite to pass. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10528#comment:39 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler