#8962: compile hang and memory blowup when using profiling and optimization -------------------------+------------------------------------------------- Reporter: ghorn | Owner: Type: bug | Status: new Priority: | Milestone: normal | Version: 7.8.1-rc2 Component: | Operating System: Linux Compiler | Type of failure: Compile-time performance bug Keywords: | Test Case: Architecture: | Blocking: x86_64 (amd64) | Difficulty: | Unknown | Blocked By: | Related Tickets: | -------------------------+------------------------------------------------- When I try to compile the following files: {{{ -- Vectorize.hs {-# OPTIONS_GHC -Wall #-} {-# LANGUAGE TypeOperators #-} module Vectorize ( GVectorize(..) ) where import GHC.Generics import Data.Vector ( Vector ) import qualified Data.Vector as V gvlength :: GVectorize f => f a -> Int gvlength = V.length . gvectorize . (gempty `asFunctorOf`) where asFunctorOf :: f a -> f b -> f a asFunctorOf x _ = x class GVectorize f where gdevectorize :: Vector a -> f a gvectorize :: f a -> Vector a gempty :: f () instance (GVectorize f, GVectorize g) => GVectorize (f :*: g) where gdevectorize v0s | V.length v0s < n0 = error $ show n0 | otherwise = f0 :*: f1 where f0 = gdevectorize v0 f1 = gdevectorize v1 n0 = gvlength f0 (v0,v1) = V.splitAt n0 v0s gvectorize (f :*: g) = gvectorize f V.++ gvectorize g gempty = gempty :*: gempty instance GVectorize f => GVectorize (M1 i c f) where gdevectorize = M1 . gdevectorize gvectorize = gvectorize . unM1 gempty = undefined -- M1 gempty instance GVectorize Par1 where gdevectorize _ = undefined gvectorize = V.singleton . unPar1 gempty = undefined -- Par1 () }}} {{{ -- Woo.hs {-# OPTIONS_GHC -Wall #-} {-# Language DeriveGeneric #-} module Woo ( Woo(..) , devectorize ) where import GHC.Generics import Data.Vector ( Vector ) import Vectorize ( GVectorize(..) ) data Woo a = MkWoo { x00 :: a , x01 :: a , x02 :: a , x03 :: a , x04 :: a , x05 :: a , x06 :: a , x07 :: a , x08 :: a , x09 :: a , x10 :: a , x11 :: a , x12 :: a , x13 :: a , x14 :: a , x15 :: a , x16 :: a , x17 :: a , x18 :: a , x19 :: a , x20 :: a , x21 :: a } deriving (Generic1) devectorize :: Vector a -> Woo a devectorize = to1 . gdevectorize }}} with `ghc -O2 -prof -fprof-auto-calls Woo.hs`, GHC seems to hang on Woo.o and the memory usage steadily creeps up (I killed it at 5GB after about 5 minutes). I don't think this is #7068 / #7898 / #8960 because `-fno-spec-constr` doesn't fix it and the end of the -v3 output is: {{{ ... ... *** SpecConstr: Result size of SpecConstr = {terms: 89,855, types: 125,614, coercions: 138,597} *** Simplifier: Result size of Simplifier iteration=1 = {terms: 428,416, types: 555,965, coercions: 855,101} Result size of Simplifier = {terms: 428,386, types: 555,815, coercions: 626,125} *** Tidy Core: Result size of Tidy Core = {terms: 428,386, types: 555,815, coercions: 626,125} writeBinIface: 190 Names writeBinIface: 495 dict entries *** CorePrep: Result size of CorePrep = {terms: 533,584, types: 600,927, coercions: 626,125} *** Stg2Stg: *** CodeOutput: *** New CodeGen: *** CPSZ: *** CPSZ: *** CPSZ: *** CPSZ: *** CPSZ: *** CPSZ: *** CPSZ: }}} and then about another 100 lines of `*** CPSZ:` before it hangs. Removing either the optimization or profiling flags fixes the bug. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8962 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler