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| author | Sebastian Graf <sebastian.graf@kit.edu> | 2022-06-07 10:10:14 +0200 |
|---|---|---|
| committer | Ben Gamari <ben@smart-cactus.org> | 2022-10-12 19:20:16 -0400 |
| commit | 26af15a009610daa32d550f3769ba1b33ca009c5 (patch) | |
| tree | 221b84dec6cce147c448972d7540b081d0a7ae95 | |
| parent | 15c496c516aa4e52457b069f67d6b2ed27a0320c (diff) | |
| download | haskell-26af15a009610daa32d550f3769ba1b33ca009c5.tar.gz | |
CprAnal: Set signatures of DFuns to top
The recursive DFun in the reproducer for #20836 also triggered a bug in CprAnal
that is observable in a debug build. The CPR signature of a recursive DFunId
was never updated and hence the optimistic arity 0 bottom signature triggered a
mismatch with the arity 1 of the binding in WorkWrap. We never miscompiled any
code because WW doesn't exploit bottom CPR signatures.
(cherry picked from commit 94f2e92a2510a3338c5201a4dcc69666fa9575f8)
| -rw-r--r-- | compiler/GHC/Core/Opt/CprAnal.hs | 13 |
1 files changed, 7 insertions, 6 deletions
diff --git a/compiler/GHC/Core/Opt/CprAnal.hs b/compiler/GHC/Core/Opt/CprAnal.hs index 3f6455c9cf..5d5ea632bf 100644 --- a/compiler/GHC/Core/Opt/CprAnal.hs +++ b/compiler/GHC/Core/Opt/CprAnal.hs @@ -398,8 +398,10 @@ cprFix orig_env orig_pairs where init_sig id -- See Note [CPR for data structures] - | isDataStructure id = topCprSig - | otherwise = mkCprSig 0 botCpr + -- Don't set the sig to bottom in this case, because cprAnalBind won't + -- update it to something reasonable. Result: Assertion error in WW + | isDataStructure id || isDFunId id = topCprSig + | otherwise = mkCprSig 0 botCpr -- See Note [Initialising strictness] in GHC.Core.Opt.DmdAnal orig_virgin = ae_virgin orig_env init_pairs | orig_virgin = [(setIdCprSig id (init_sig id), rhs) | (id, rhs) <- orig_pairs ] @@ -464,10 +466,10 @@ cprAnalBind env id rhs | isDFunId id -- Never give DFuns the CPR property; we'll never save allocs. = (id, rhs, extendSigEnv env id topCprSig) -- See Note [CPR for data structures] - | isDataStructure id - = (id, rhs, env) -- Data structure => no code => no need to analyse rhs + | isDataStructure id -- Data structure => no code => no need to analyse rhs + = (id, rhs, env) | otherwise - = (id', rhs', env') + = (id `setIdCprSig` sig', rhs', env') where (rhs_ty, rhs') = cprAnal env rhs -- possibly trim thunk CPR info @@ -481,7 +483,6 @@ cprAnalBind env id rhs -- See Note [The OPAQUE pragma and avoiding the reboxing of results] sig' | isOpaquePragma (idInlinePragma id) = topCprSig | otherwise = sig - id' = setIdCprSig id sig' env' = extendSigEnv env id sig' -- See Note [CPR for thunks] |