diff options
Diffstat (limited to 'compiler/specialise/Specialise.hs')
| -rw-r--r-- | compiler/specialise/Specialise.hs | 22 |
1 files changed, 21 insertions, 1 deletions
diff --git a/compiler/specialise/Specialise.hs b/compiler/specialise/Specialise.hs index e3501dfd38..008561c4b3 100644 --- a/compiler/specialise/Specialise.hs +++ b/compiler/specialise/Specialise.hs @@ -449,7 +449,7 @@ The SpecEnv of an Id maps a list of types (the template) to an expression [Type] |-> Expr -For example, if f has this SpecInfo: +For example, if f has this RuleInfo: [Int, a] -> \d:Ord Int. f' a @@ -1324,6 +1324,26 @@ specCalls mb_mod env rules_for_me calls_for_me fn rhs ; return (Just ((spec_f_w_arity, spec_rhs), final_uds, spec_env_rule)) } } +{- +Note [Orphans and auto-generated rules] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +When we specialise an INLINEABLE function, or when we have +-fspecialise-aggressively, we auto-generate RULES that are orphans. +We don't want to warn about these, or we'd generate a lot of warnings. +Thus, we only warn about user-specified orphan rules. + +Indeed, we don't even treat the module as an orphan module if it has +auto-generated *rule* orphans. Orphan modules are read every time we +compile, so they are pretty obtrusive and slow down every compilation, +even non-optimised ones. (Reason: for type class instances it's a +type correctness issue.) But specialisation rules are strictly for +*optimisation* only so it's fine not to read the interface. + +What this means is that a SPEC rules from auto-specialisation in +module M will be used in other modules only if M.hi has been read for +some other reason, which is actually pretty likely. +-} + bindAuxiliaryDicts :: SpecEnv -> [DictId] -> [CoreExpr] -- Original dict bndrs, and the witnessing expressions |