Alp, Is this related to #15570. If so, it'd be good to make that connection. S | -----Original Message----- | From: ghc-commits On Behalf Of | git@git.haskell.org | Sent: 02 September 2018 22:16 | To: ghc-commits@haskell.org | Subject: [commit: ghc] master: make iToBase62's inner loop stricter in | one of its arguments (ed78951) | | Repository : ssh://git@git.haskell.org/ghc | | On branch : master | Link : | https://na01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fghc.haske | ll.org%2Ftrac%2Fghc%2Fchangeset%2Fed789516e201e4fad771e5588da47a62e53b42b | 8%2Fghc&data=02%7C01%7Csimonpj%40microsoft.com%7Cea714d654b04488aada9 | 08d6111955e2%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C636715197856324 | 232&sdata=3Oo7y3FCIzEZVAWc%2FPl6ZXwji2QM2CWWAI3UfHqxDn0%3D&reserv | ed=0 | | >--------------------------------------------------------------- | | commit ed789516e201e4fad771e5588da47a62e53b42b8 | Author: Alp Mestanogullari | Date: Sun Sep 2 22:06:55 2018 +0200 | | make iToBase62's inner loop stricter in one of its arguments | | Summary: | hadrian's support for dynamic ways is currently broken (see | hadrian#641 [1]). | The stage 1 GHCs that hadrian produces end up producing bad code for | the `iToBase62` function after a few optimisation passes. | | In the case where `quotRem` returns (overflowError, 0), | GHC isn't careful enough to realise q is _|_ and happily inlines, | distributes and floats code around until we end up trying to access | index `minBound :: Int` of an array of 62 chars, as a result of | inlining | the definition of `quotRem` for Ints, in particular the minBound | branch [2]. | | I will separately look into reproducing the bad transformation on a | small | self-contained example and filling a ticket. | | [1]: | https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.c | om%2Fsnowleopard%2Fhadrian%2Fissues%2F641&data=02%7C01%7Csimonpj%40mi | crosoft.com%7Cea714d654b04488aada908d6111955e2%7C72f988bf86f141af91ab2d7c | d011db47%7C1%7C0%7C636715197856324232&sdata=a7dM0YbraOY69xKhJcwVuQqBn | 3n3nTdVuMFNjie6iHA%3D&reserved=0 | [2]: | https://git.haskell.org/ghc.git/blob/HEAD:/libraries/base/GHC/Real.hs#l36 | 6 | | Test Plan: fixes hadrian#641 | | Reviewers: bgamari, tdammers | | Reviewed By: tdammers | | Subscribers: tdammers, rwbarton, carter | | Differential Revision: https://phabricator.haskell.org/D5106 | | | >--------------------------------------------------------------- | | ed789516e201e4fad771e5588da47a62e53b42b8 | compiler/basicTypes/Unique.hs | 2 +- | 1 file changed, 1 insertion(+), 1 deletion(-) | | diff --git a/compiler/basicTypes/Unique.hs | b/compiler/basicTypes/Unique.hs index 4a709d2..b5c0fce 100644 | --- a/compiler/basicTypes/Unique.hs | +++ b/compiler/basicTypes/Unique.hs | @@ -325,7 +325,7 @@ iToBase62 n_ | go n cs | n < 62 | = let !c = chooseChar62 n in c : cs | | otherwise | - = go q (c : cs) where (q, r) = quotRem n 62 | + = go q (c : cs) where (!q, r) = quotRem n 62 | !c = chooseChar62 r | | chooseChar62 :: Int -> Char | | _______________________________________________ | ghc-commits mailing list | ghc-commits@haskell.org | https://na01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fmail.hask | ell.org%2Fcgi-bin%2Fmailman%2Flistinfo%2Fghc- | commits&data=02%7C01%7Csimonpj%40microsoft.com%7Cea714d654b04488aada9 | 08d6111955e2%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C636715197856324 | 232&sdata=5oKSdyvdcyJlPR%2FtNUNuptlsFuv9jJA%2FVmc7AOid5mc%3D&rese | rved=0