Commit f03b9562 authored by simonpj@microsoft.com's avatar simonpj@microsoft.com

Don't do SpecConstr on NOINLINE things (Trac #4064)

Since the RULE from specialising gets the same Activation as
the inlining for the Id itself there's no point in specialising
a NOINLINE thing, because the rule will be permanently switched
off.

See Note [Transfer activation] in SpecConstr
and Note [Auto-specialisation and RULES] in Specialise.
parent 757d3c5a
......@@ -36,6 +36,7 @@ import Var
import VarEnv
import VarSet
import Name
import BasicTypes
import DynFlags ( DynFlags(..) )
import StaticFlags ( opt_PprStyle_Debug )
import Maybes ( orElse, catMaybes, isJust, isNothing )
......@@ -1172,6 +1173,7 @@ specialise
specialise env force_spec bind_calls (RI fn _ arg_bndrs body arg_occs)
spec_info@(SI specs spec_count mb_unspec)
| not (isBottomingId fn) -- Note [Do not specialise diverging functions]
, not (isNeverActive (idInlineActivation fn)) -- See Note [Transfer activation]
, notNull arg_bndrs -- Only specialise functions
, Just all_calls <- lookupVarEnv bind_calls fn
= do { (boring_call, pats) <- callsToPats env specs arg_occs all_calls
......@@ -1278,6 +1280,7 @@ spec_one env fn arg_bndrs body (call_pat@(qvars, pats), rule_number)
rule_rhs = mkVarApps (Var spec_id) spec_call_args
inline_act = idInlineActivation fn
rule = mkLocalRule rule_name inline_act fn_name qvars pats rule_rhs
-- See Note [Transfer activation]
; return (spec_usg, OS call_pat rule spec_id spec_rhs) }
calcSpecStrictness :: Id -- The original function
......@@ -1313,6 +1316,10 @@ specialised RHS, and that can lead directly to exponential behaviour.
Note [Transfer activation]
~~~~~~~~~~~~~~~~~~~~~~~~~~
This note is for SpecConstr, but exactly the same thing
happens in the overloading specialiser; see
Note [Auto-specialisation and RULES] in Specialise.
In which phase should the specialise-constructor rules be active?
Originally I made them always-active, but Manuel found that this
defeated some clever user-written rules. Then I made them active only
......@@ -1323,8 +1330,9 @@ simplCore/should_compile/spec-inline.
So now I just use the inline-activation of the parent Id, as the
activation for the specialiation RULE, just like the main specialiser;
see Note [Auto-specialisation and RULES] in Specialise.
This in turn means there is no point in specialising NOINLINE things,
so we test for that.
Note [Transfer strictness]
~~~~~~~~~~~~~~~~~~~~~~~~~~
......
Markdown is supported
0% or .
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment