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| author | Sebastian Graf <sebastian.graf@kit.edu> | 2022-02-28 14:52:36 +0100 |
|---|---|---|
| committer | Marge Bot <ben+marge-bot@smart-cactus.org> | 2022-03-13 18:12:48 -0400 |
| commit | 76b94b726f6e21bb2a46ae04e4a1be2cba45a3dc (patch) | |
| tree | 8db126a5c8718140a6cd7bdd8f3a20df257f580c /compiler/GHC/Core/Opt/Specialise.hs | |
| parent | ad83553153278947f439951d79a842527f2f0983 (diff) | |
| download | haskell-76b94b726f6e21bb2a46ae04e4a1be2cba45a3dc.tar.gz | |
Worker/wrapper: Preserve float barriers (#21150)
Issue #21150 shows that worker/wrapper allocated a worker function for a
function with multiple calls that said "called at most once" when the first
argument was absent. That's bad!
This patch makes it so that WW preserves at least one non-one-shot value lambda
(see `Note [Preserving float barriers]`) by passing around `void#` in place of
absent arguments.
Fixes #21150.
Since the fix is pretty similar to `Note [Protecting the last value argument]`,
I put the logic in `mkWorkerArgs`. There I realised (#21204) that
`-ffun-to-thunk` is basically useless with `-ffull-laziness`, so I deprecated
the flag, simplified and split into `needsVoidWorkerArg`/`addVoidWorkerArg`.
SpecConstr is another client of that API.
Fixes #21204.
Metric Decrease:
T14683
Diffstat (limited to 'compiler/GHC/Core/Opt/Specialise.hs')
| -rw-r--r-- | compiler/GHC/Core/Opt/Specialise.hs | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/compiler/GHC/Core/Opt/Specialise.hs b/compiler/GHC/Core/Opt/Specialise.hs index cbf3a4e10e..d80e78f685 100644 --- a/compiler/GHC/Core/Opt/Specialise.hs +++ b/compiler/GHC/Core/Opt/Specialise.hs @@ -1519,7 +1519,7 @@ specCalls spec_imp env existing_rules calls_for_me fn rhs -- Maybe add a void arg to the specialised function, -- to avoid unlifted bindings -- See Note [Specialisations Must Be Lifted] - -- C.f. GHC.Core.Opt.WorkWrap.Utils.mkWorkerArgs + -- C.f. GHC.Core.Opt.WorkWrap.Utils.needsVoidWorkerArg add_void_arg = isUnliftedType spec_fn_ty1 && not (isJoinId fn) (spec_bndrs, spec_rhs, spec_fn_ty) | add_void_arg = ( voidPrimId : spec_bndrs1 |