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| author | Simon Peyton Jones <simon.peytonjones@gmail.com> | 2023-01-12 22:21:40 +0000 |
|---|---|---|
| committer | Simon Peyton Jones <simon.peytonjones@gmail.com> | 2023-01-31 08:54:52 +0000 |
| commit | ae22d1096df1bd83b5ce9ef5d8c2bd8c00e20bad (patch) | |
| tree | dc345c52cefcb688e3be7447551cb0a0bedfb492 /compiler/GHC/StgToJS | |
| parent | b69461a06166d2b1c600df87b87656d09122fb7c (diff) | |
| download | haskell-wip/T22745.tar.gz | |
Improve exprOkForSpeculation for classopswip/T22745
This patch fixes #22745 and #15205, which are about GHC's
failure to discard unnecessary superclass selections that
yield coercions. See
GHC.Core.Utils Note [exprOkForSpeculation and type classes]
The main changes are:
* Write new Note [NON-BOTTOM_DICTS invariant] in GHC.Core, and
refer to it
* Define new function isTerminatingType, to identify those
guaranteed-terminating dictionary types.
* exprOkForSpeculation has a new (very simple) case for ClassOpId
* ClassOpId has a new field that says if the return type is
an unlifted type, or a terminating type.
This was surprisingly tricky to get right. In particular note
that unlifted types are not terminating types; you can write an
expression of unlifted type, that diverges. Not so for dictionaries
(or, more precisely, for the dictionaries that GHC constructs).
Metric Decrease:
LargeRecord
Diffstat (limited to 'compiler/GHC/StgToJS')
| -rw-r--r-- | compiler/GHC/StgToJS/Expr.hs | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/compiler/GHC/StgToJS/Expr.hs b/compiler/GHC/StgToJS/Expr.hs index fd6d09585f..b398cdf501 100644 --- a/compiler/GHC/StgToJS/Expr.hs +++ b/compiler/GHC/StgToJS/Expr.hs @@ -51,7 +51,6 @@ import GHC.StgToJS.Utils import GHC.StgToJS.Stack import GHC.StgToJS.Ids -import GHC.Types.Basic import GHC.Types.CostCentre import GHC.Types.Tickish import GHC.Types.Var.Set @@ -484,7 +483,7 @@ genStaticRefs lv | otherwise = do unfloated <- State.gets gsUnfloated let xs = filter (\x -> not (elemUFM x unfloated || - typeLevity_maybe (idType x) == Just Unlifted)) + definitelyUnliftedType (idType x))) (dVarSetElems sv) CIStaticRefs . catMaybes <$> mapM getStaticRef xs where |