diff options
| -rw-r--r-- | compiler/coreSyn/CoreUnfold.hs | 21 |
1 files changed, 19 insertions, 2 deletions
diff --git a/compiler/coreSyn/CoreUnfold.hs b/compiler/coreSyn/CoreUnfold.hs index 6535d37307..2bb2b598f3 100644 --- a/compiler/coreSyn/CoreUnfold.hs +++ b/compiler/coreSyn/CoreUnfold.hs @@ -1287,6 +1287,23 @@ traceInline dflags inline_id str doc result | otherwise = result +-- | This is an awful but temporary workaround for #17615, where the +-- case analysis from the 'ufVeryAggressive' selector causes the entire +-- 'DynFlags' to be unpacked into local bindings (due to binder swap). This +-- results in a tremendous amount of stack spillage, severely bloating the code +-- generated for 'callSiteInline'. +-- +-- The right solution here is likely to fix binder swap to avoid this terrible +-- behavior (since there are likely other instances of this as well) but this +-- case was serious enough that it showed up in a CPU profile and consequently +-- I wanted to fix it for 8.10. +-- +-- The workaround avoids the binder swap transformation by preventing +-- 'ufVeryAggressive' from inlining into 'callSiteInline'. +very_aggressive :: DynFlags -> Bool +very_aggressive = ufVeryAggressive +{-# NOINLINE very_aggressive #-} + tryUnfolding :: DynFlags -> Id -> Bool -> [ArgSummary] -> CallCtxt -> CoreExpr -> Bool -> Bool -> UnfoldingGuidance -> Maybe CoreExpr @@ -1297,7 +1314,7 @@ tryUnfolding dflags id lone_variable UnfNever -> traceInline dflags id str (text "UnfNever") Nothing UnfWhen { ug_arity = uf_arity, ug_unsat_ok = unsat_ok, ug_boring_ok = boring_ok } - | enough_args && (boring_ok || some_benefit || ufVeryAggressive dflags) + | enough_args && (boring_ok || some_benefit || very_aggressive dflags) -- See Note [INLINE for small functions (3)] -> traceInline dflags id str (mk_doc some_benefit empty True) (Just unf_template) | otherwise @@ -1307,7 +1324,7 @@ tryUnfolding dflags id lone_variable enough_args = (n_val_args >= uf_arity) || (unsat_ok && n_val_args > 0) UnfIfGoodArgs { ug_args = arg_discounts, ug_res = res_discount, ug_size = size } - | ufVeryAggressive dflags + | very_aggressive dflags -> traceInline dflags id str (mk_doc some_benefit extra_doc True) (Just unf_template) | is_wf && some_benefit && small_enough -> traceInline dflags id str (mk_doc some_benefit extra_doc True) (Just unf_template) |