[Git][ghc/ghc][master] simplifier: Fix space leak during demand analysis

[Marge Bot (@marge-bot)]

Marge Bot pushed to branch master at Glasgow Haskell Compiler / GHC


Commits:
3a5bebf8 by Matthew Pickering at 2024-08-28T14:16:42-04:00
simplifier: Fix space leak during demand analysis

The lazy structure (a list) in a strict field in `DmdType` is not fully
forced which leads to a very large thunk build-up.

It seems there is likely still more work to be done here as it seems we
may be trading space usage for work done. For now, this is the right
choice as rather than using all the memory on my computer, compilation
just takes a little bit longer.

See #25196

- - - - -


1 changed file:

- compiler/GHC/Types/Demand.hs


Changes:

=====================================
compiler/GHC/Types/Demand.hs
=====================================
@@ -1913,7 +1913,7 @@ multDmdType :: Card -> DmdType -> DmdType
 multDmdType n (DmdType fv args)
   = -- pprTrace "multDmdType" (ppr n $$ ppr fv $$ ppr (multDmdEnv n fv)) $
     DmdType (multDmdEnv n fv)
-            (map (multDmd n) args)
+            (strictMap (multDmd n) args)
 
 peelFV :: DmdType -> Var -> (DmdType, Demand)
 peelFV (DmdType fv ds) id = -- pprTrace "rfv" (ppr id <+> ppr dmd $$ ppr fv)



View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/3a5bebf85071f36c0b81cf888df5f5af27f70ee9

-- 
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/3a5bebf85071f36c0b81cf888df5f5af27f70ee9
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