diff options
Diffstat (limited to 'compiler/GHC/Iface/Tidy.hs')
| -rw-r--r-- | compiler/GHC/Iface/Tidy.hs | 134 |
1 files changed, 81 insertions, 53 deletions
diff --git a/compiler/GHC/Iface/Tidy.hs b/compiler/GHC/Iface/Tidy.hs index 76c0a7b2cb..373a881c0c 100644 --- a/compiler/GHC/Iface/Tidy.hs +++ b/compiler/GHC/Iface/Tidy.hs @@ -24,16 +24,17 @@ import GHC.Tc.Utils.Env import GHC.Core import GHC.Core.Unfold -import GHC.Core.Unfold.Make +-- import GHC.Core.Unfold.Make import GHC.Core.FVs import GHC.Core.Tidy -import GHC.Core.Seq (seqBinds) +import GHC.Core.Seq ( seqBinds ) import GHC.Core.Opt.Arity ( exprArity, typeArity, exprBotStrictness_maybe ) import GHC.Core.InstEnv import GHC.Core.Type ( Type, tidyTopType ) import GHC.Core.DataCon import GHC.Core.TyCon import GHC.Core.Class +import GHC.Core.Opt.OccurAnal ( occurAnalyseExpr ) import GHC.Iface.Tidy.StaticPtrTable import GHC.Iface.Env @@ -383,8 +384,7 @@ tidyProgram opts (ModGuts { mg_module = mod (unfold_env, tidy_occ_env) <- chooseExternalIds opts mod binds implicit_binds imp_rules let (trimmed_binds, trimmed_rules) = findExternalRules opts binds imp_rules unfold_env - let uf_opts = opt_unfolding_opts opts - (tidy_env, tidy_binds) <- tidyTopBinds uf_opts unfold_env boot_exports tidy_occ_env trimmed_binds + (tidy_env, tidy_binds) <- tidyTopBinds unfold_env boot_exports tidy_occ_env trimmed_binds -- See Note [Grand plan for static forms] in GHC.Iface.Tidy.StaticPtrTable. (spt_entries, mcstub, tidy_binds') <- case opt_static_ptr_opts opts of @@ -1152,60 +1152,49 @@ tidyTopName mod name_cache maybe_ref occ_env id -- -- * subst_env: A Var->Var mapping that substitutes the new Var for the old -tidyTopBinds :: UnfoldingOpts - -> UnfoldEnv +tidyTopBinds :: UnfoldEnv -> NameSet -> TidyOccEnv -> CoreProgram -> IO (TidyEnv, CoreProgram) -tidyTopBinds uf_opts unfold_env boot_exports init_occ_env binds +tidyTopBinds unfold_env boot_exports init_occ_env binds = do let result = tidy init_env binds seqBinds (snd result) `seq` return result -- This seqBinds avoids a spike in space usage (see #13564) where init_env = (init_occ_env, emptyVarEnv) - tidy = mapAccumL (tidyTopBind uf_opts unfold_env boot_exports) + tidy = mapAccumL (tidyTopBind unfold_env boot_exports) ------------------------ -tidyTopBind :: UnfoldingOpts - -> UnfoldEnv +tidyTopBind :: UnfoldEnv -> NameSet -> TidyEnv -> CoreBind -> (TidyEnv, CoreBind) -tidyTopBind uf_opts unfold_env boot_exports +tidyTopBind unfold_env boot_exports (occ_env,subst1) (NonRec bndr rhs) = (tidy_env2, NonRec bndr' rhs') where - Just (name',show_unfold) = lookupVarEnv unfold_env bndr - (bndr', rhs') = tidyTopPair uf_opts show_unfold boot_exports tidy_env2 name' (bndr, rhs) + (bndr', rhs') = tidyTopPair unfold_env boot_exports tidy_env2 (bndr, rhs) subst2 = extendVarEnv subst1 bndr bndr' tidy_env2 = (occ_env, subst2) -tidyTopBind uf_opts unfold_env boot_exports (occ_env, subst1) (Rec prs) +tidyTopBind unfold_env boot_exports (occ_env, subst1) (Rec prs) = (tidy_env2, Rec prs') where - prs' = [ tidyTopPair uf_opts show_unfold boot_exports tidy_env2 name' (id,rhs) - | (id,rhs) <- prs, - let (name',show_unfold) = - expectJust "tidyTopBind" $ lookupVarEnv unfold_env id - ] - - subst2 = extendVarEnvList subst1 (bndrs `zip` map fst prs') + prs' = map (tidyTopPair unfold_env boot_exports tidy_env2) prs + subst2 = extendVarEnvList subst1 (map fst prs `zip` map fst prs') tidy_env2 = (occ_env, subst2) - - bndrs = map fst prs + -- This is where we "tie the knot": tidy_env2 is fed into tidyTopPair ----------------------------------------------------------- -tidyTopPair :: UnfoldingOpts - -> Bool -- show unfolding +tidyTopPair :: UnfoldEnv -> NameSet -> TidyEnv -- The TidyEnv is used to tidy the IdInfo -- It is knot-tied: don't look at it! - -> Name -- New name -> (Id, CoreExpr) -- Binder and RHS before tidying -> (Id, CoreExpr) -- This function is the heart of Step 2 @@ -1214,17 +1203,18 @@ tidyTopPair :: UnfoldingOpts -- group, a variable late in the group might be mentioned -- in the IdInfo of one early in the group -tidyTopPair uf_opts show_unfold boot_exports rhs_tidy_env name' (bndr, rhs) +tidyTopPair unfold_env boot_exports rhs_tidy_env (bndr, rhs) = -- pprTrace "tidyTop" (ppr name' <+> ppr details <+> ppr rhs) $ (bndr1, rhs1) where + Just (name',show_unfold) = lookupVarEnv unfold_env bndr !cbv_bndr = tidyCbvInfoTop boot_exports bndr rhs bndr1 = mkGlobalId details name' ty' idinfo' details = idDetails cbv_bndr -- Preserve the IdDetails ty' = tidyTopType (idType cbv_bndr) rhs1 = tidyExpr rhs_tidy_env rhs - idinfo' = tidyTopIdInfo uf_opts rhs_tidy_env name' ty' + idinfo' = tidyTopIdInfo rhs_tidy_env name' ty' rhs rhs1 (idInfo cbv_bndr) show_unfold -- tidyTopIdInfo creates the final IdInfo for top-level @@ -1234,9 +1224,9 @@ tidyTopPair uf_opts show_unfold boot_exports rhs_tidy_env name' (bndr, rhs) -- Indeed, CorePrep must eta expand where necessary to make -- the manifest arity equal to the claimed arity. -- -tidyTopIdInfo :: UnfoldingOpts -> TidyEnv -> Name -> Type +tidyTopIdInfo :: TidyEnv -> Name -> Type -> CoreExpr -> CoreExpr -> IdInfo -> Bool -> IdInfo -tidyTopIdInfo uf_opts rhs_tidy_env name rhs_ty orig_rhs tidy_rhs idinfo show_unfold +tidyTopIdInfo rhs_tidy_env name rhs_ty orig_rhs tidy_rhs idinfo show_unfold | not is_external -- For internal Ids (not externally visible) = vanillaIdInfo -- we only need enough info for code generation -- Arity and strictness info are enough; @@ -1292,31 +1282,20 @@ tidyTopIdInfo uf_opts rhs_tidy_env name rhs_ty orig_rhs tidy_rhs idinfo show_unf Just (arity, _, _) -> not (isDeadEndAppSig id_sig arity) --------- Unfolding ------------ + -- Force unfold_info (hence bangs), otherwise the old unfolding + -- is retained during code generation. See #22071 + unf_info = realUnfoldingInfo idinfo - -- Force this, otherwise the old unfolding is retained over code generation - -- See #22071 - !unfold_info - | isCompulsoryUnfolding unf_info || show_unfold - = tidyUnfolding rhs_tidy_env unf_info unf_from_rhs - | otherwise - = minimal_unfold_info !minimal_unfold_info = trimUnfolding unf_info - unf_from_rhs = mkFinalUnfolding uf_opts InlineRhs final_sig tidy_rhs - -- NB: do *not* expose the worker if show_unfold is off, - -- because that means this thing is a loop breaker or - -- marked NOINLINE or something like that - -- This is important: if you expose the worker for a loop-breaker - -- then you can make the simplifier go into an infinite loop, because - -- in effect the unfolding is exposed. See #1709 - -- - -- You might think that if show_unfold is False, then the thing should - -- not be w/w'd in the first place. But a legitimate reason is this: - -- the function returns bottom - -- In this case, show_unfold will be false (we don't expose unfoldings - -- for bottoming functions), but we might still have a worker/wrapper - -- split (see Note [Worker/wrapper for bottoming functions] in - -- GHC.Core.Opt.WorkWrap) + !unfold_info | isCompulsoryUnfolding unf_info || show_unfold + = tidyTopUnfolding rhs_tidy_env tidy_rhs unf_info + | otherwise + = minimal_unfold_info +-- unf_from_rhs = mkFinalUnfolding uf_opts InlineRhs final_sig orig_rhs + -- NB: use `orig_rhs` not `tidy_rhs` in this call to mkFinalUnfolding + -- else you get a black hole (#22122). Reason: mkFinalUnfolding + -- looks at IdInfo, and that is knot-tied in tidyTopBind (the Rec case) --------- Arity ------------ -- Usually the Id will have an accurate arity on it, because @@ -1328,10 +1307,59 @@ tidyTopIdInfo uf_opts rhs_tidy_env name rhs_ty orig_rhs tidy_rhs idinfo show_unf arity = exprArity orig_rhs `min` typeArity rhs_ty -- orig_rhs: using tidy_rhs would make a black hole, since -- exprArity uses the arities of Ids inside the rhs + -- -- typeArity: see Note [Arity invariants for bindings] -- in GHC.Core.Opt.Arity -{- +------------ Unfolding -------------- +tidyTopUnfolding :: TidyEnv -> CoreExpr -> Unfolding -> Unfolding +tidyTopUnfolding _ _ NoUnfolding = NoUnfolding +tidyTopUnfolding _ _ BootUnfolding = BootUnfolding +tidyTopUnfolding _ _ (OtherCon {}) = evaldUnfolding + +tidyTopUnfolding tidy_env _ df@(DFunUnfolding { df_bndrs = bndrs, df_args = args }) + = df { df_bndrs = bndrs', df_args = map (tidyExpr tidy_env') args } + where + (tidy_env', bndrs') = tidyBndrs tidy_env bndrs + +tidyTopUnfolding tidy_env tidy_rhs + unf@(CoreUnfolding { uf_tmpl = unf_rhs, uf_src = src }) + = -- See Note [tidyTopUnfolding: avoiding black holes] + unf { uf_tmpl = tidy_unf_rhs } + where + tidy_unf_rhs | isStableSource src + = tidyExpr tidy_env unf_rhs -- Preserves OccInfo in unf_rhs + | otherwise + = occurAnalyseExpr tidy_rhs -- Do occ-anal + +{- Note [tidyTopUnfolding: avoiding black holes] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +When we are exposing all unfoldings we don't want to tidy the unfolding +twice -- we just want to use the tidied RHS. That tidied RHS itself +contains fully-tidied Ids -- it is knot-tied. So the uf_tmpl for the +unfolding contains stuff we can't look at. Now consider (#22112) + foo = foo +If we freshly compute the uf_is_value field for foo's unfolding, +we'll call `exprIsValue`, which will look at foo's unfolding! +Whether or not the RHS is a value depends on whether foo is a value... +black hole. + +In the Simplifier we deal with this by not giving `foo` an unfolding +in its own RHS. And we could do that here. But it's qite nice +to common everything up to a single Id for foo, used everywhere. + +And it's not too hard: simply leave the unfolding undisturbed, except +tidy the uf_tmpl field. Hence tidyTopUnfolding does + unf { uf_tmpl = tidy_unf_rhs } + +Don't mess with uf_is_value, or guidance; in particular don't recompute +them from tidy_unf_rhs. + +And (unlike tidyNestedUnfolding) don't deep-seq the new unfolding, +because that'll cause a black hole (I /think/ because occurAnalyseExpr +looks in IdInfo). + + ************************************************************************ * * Old, dead, type-trimming code |