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| author | David Feuer <david.feuer@gmail.com> | 2017-03-09 10:34:42 -0500 |
|---|---|---|
| committer | Ben Gamari <ben@smart-cactus.org> | 2017-03-09 10:34:48 -0500 |
| commit | 7b087aeba45a7a70a5553ef4c116ee67660423e8 (patch) | |
| tree | 7b34cfd8991c8cb73265c2ae2f9c1b61d2d99076 | |
| parent | 7b80168bc11ba1fa3ef7ebfcdf3b4d67f467b0dc (diff) | |
| download | haskell-7b087aeba45a7a70a5553ef4c116ee67660423e8.tar.gz | |
Make raiseIO# produce topRes
Make `raiseIO#` produce `topRes` instead of `ExnRes`. `ExnRes` leads to
demand analysis being too aggressive, IMO, allowing imprecise exceptions
produced by `throw` to replace exceptions thrown by `throwIO` that
would like to think of as precise.
This fixes that, but is certanly much more conservative than we would
ideally like. Let's see how bad it is.
Fixes Trac #13380
Reviewers: austin, bgamari
Subscribers: rwbarton, thomie
Differential Revision: https://phabricator.haskell.org/D3301
| -rw-r--r-- | compiler/prelude/primops.txt.pp | 10 |
1 files changed, 4 insertions, 6 deletions
diff --git a/compiler/prelude/primops.txt.pp b/compiler/prelude/primops.txt.pp index 1d102238ba..64971a3743 100644 --- a/compiler/prelude/primops.txt.pp +++ b/compiler/prelude/primops.txt.pp @@ -2005,11 +2005,9 @@ primop RaiseOp "raise#" GenPrimOp -- must be *precise* - we don't want the strictness analyser turning -- one kind of bottom into another, as it is allowed to do in pure code. -- --- But we *do* want to know that it returns bottom after --- being applied to two arguments, so that this function is strict in y --- f x y | x>0 = raiseIO blah --- | y>0 = return 1 --- | otherwise = return 2 +-- We currently produce topRes, which is much too conservative (interfering +-- with dead code elimination, unfortunately), but nothing else we currently +-- have on tap is actually correct. -- -- TODO Check that the above notes on @f@ are valid. The function successfully -- produces an IO exception when compiled without optimization. If we analyze @@ -2021,7 +2019,7 @@ primop RaiseOp "raise#" GenPrimOp primop RaiseIOOp "raiseIO#" GenPrimOp a -> State# RealWorld -> (# State# RealWorld, b #) with - strictness = { \ _arity -> mkClosedStrictSig [topDmd, topDmd] exnRes } + strictness = { \ _arity -> mkClosedStrictSig [topDmd, topDmd] topRes } out_of_line = True has_side_effects = True |