%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 2000-2018. All Rights Reserved.
%%
%% Licensed under the Apache License, Version 2.0 (the "License");
%% you may not use this file except in compliance with the License.
%% You may obtain a copy of the License at
%%
%% http://www.apache.org/licenses/LICENSE-2.0
%%
%% Unless required by applicable law or agreed to in writing, software
%% distributed under the License is distributed on an "AS IS" BASIS,
%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
%% See the License for the specific language governing permissions and
%% limitations under the License.
%%
%% %CopyrightEnd%
%%
%% Purpose : Function inlining optimisation for Core.
%% This simple function inliner works in two stages:
%%
%% 1. First it extracts all the inlineable functions, either given
%% explicitly or of light enough weight, and inlines them with
%% themselves. This inlining only uses lighter functions to save
%% recursion and a real code explosion.
%%
%% 2. Run through the rest of the functions inlining all calls to
%% inlineable functions.
%%
%% The weight function is VERY simple, we count the number of nodes in
%% the function body. We would like to remove non-exported,
%% inlineable functions but this is not trivial as they may be
%% (mutually) recursive.
%%
%% This module will catch many access functions and allow code to use
%% extra functions for clarity which are then explicitly inlined for
%% speed with a compile attribute. See the example below.
%%
%% It is not clear that inlining will give you very much.
-module(sys_core_inline).
-export([module/2]).
-import(lists, [member/2,map/2,foldl/3,mapfoldl/3,keydelete/3]).
-include("core_parse.hrl").
%% Inline status.
-record(inline, {exports=[],thresh=0,inline=[]}).
%% General function info.
-record(fstat, {func :: atom(), %Function name
arity :: byte(), % arity
def, %Original definition
weight=0, %Weight
inline=false :: boolean(), %Inline func flag
modified=false :: boolean()}). %Mod flag
%% Inlineable function info.
-record(ifun, {func :: atom(), %Function name
arity :: byte(), % arity
vars, %Fun vars
body, % body
weight}). %Weight
-spec module(#c_module{}, [_]) -> {'ok', #c_module{}}.
module(#c_module{exports=Es,defs=Ds0}=Mod, Opts) ->
case inline_option(Opts) of
{Thresh,Fs} when is_integer(Thresh), Thresh > 0; Fs =/= [] ->
case proplists:get_bool(verbose, Opts) of
true ->
io:format("Old inliner: threshold=~p functions=~p\n",
[Thresh,Fs]);
false -> ok
end,
Ds1 = inline(Ds0, #inline{exports=Es,thresh=Thresh,inline=Fs}),
{ok,Mod#c_module{defs=Ds1}};
_Other -> {ok,Mod}
end.
inline_option(Opts) ->
foldl(fun ({inline,{_,_}=Val}, {T,Fs}) ->
{T,[Val|Fs]};
({inline,Val}, {T,Fs}) when is_list(Val) ->
{T,Val ++ Fs};
({inline,Val}, {_,Fs}) when is_integer(Val) ->
{Val,Fs};
(_Opt, {_,_}=Def) -> Def
end, {0,[]}, Opts).
%% inline([Func], Stat) -> [Func].
%% Here we do all the work.
inline(Fs0, St0) ->
%% Generate list of augmented functions.
Fs1 = map(fun ({#c_var{name={F,A}},#c_fun{body=B}}=Def) ->
Weight = cerl_trees:fold(fun weight_func/2, 0, B),
#fstat{func=F,arity=A,def=Def,weight=Weight}
end, Fs0),
%% Get inlineable functions, and inline them with themselves.
{Fs2,Is0} = mapfoldl(fun (Fst, Ifs) ->
case is_inlineable(Fst, St0#inline.thresh,
St0#inline.inline) of
true ->
{_,Ffun} = Fst#fstat.def,
If = #ifun{func=Fst#fstat.func,
arity=Fst#fstat.arity,
vars=Ffun#c_fun.vars,
body=Ffun#c_fun.body,
weight=Fst#fstat.weight},
{Fst#fstat{inline=true},[If|Ifs]};
false -> {Fst,Ifs}
end
end, [], Fs1),
Is1 = map(fun (#ifun{body=B}=If) ->
If#ifun{body=cerl_trees:map(match_fail_fun(), B)}
end, Is0),
Is2 = [inline_inline(If, Is1) || If <- Is1],
%% We would like to remove inlined, non-exported functions here,
%% but this can be difficult as they may be recursive.
%% Use fixed inline functions on all functions.
Fs = [inline_func(F, Is2) || F <- Fs2],
%% Regenerate module body.
[Def || #fstat{def=Def} <- Fs].
%% is_inlineable(Fstat, Thresh, [Inline]) -> boolean().
is_inlineable(#fstat{weight=W}, Thresh, _Ofs) when W =< Thresh -> true;
is_inlineable(#fstat{func=F,arity=A}, _Thresh, Ofs) ->
member({F,A}, Ofs).
%% inline_inline(Ifun, [Inline]) -> Ifun.
%% Try to inline calls in an inlineable function. To save us from a
%% to great code explosion we only inline functions "smaller" than
%% ourselves.
inline_inline(#ifun{body=B,weight=Iw}=If, Is) ->
Inline = fun (#c_apply{op=#c_var{name={F,A}},args=As}=Call) ->
case find_inl(F, A, Is) of
#ifun{vars=Vs,body=B2,weight=W} when W < Iw ->
#c_let{vars=Vs,
arg=kill_id_anns(core_lib:make_values(As)),
body=kill_id_anns(B2)};
_Other -> Call
end;
(Core) -> Core
end,
If#ifun{body=cerl_trees:map(Inline, B)}.
%% inline_func(Fstat, [Inline]) -> Fstat.
%% Try to inline calls in a normal function. Here we inline anything
%% in the inline list.
inline_func(#fstat{def={Name,F0}}=Fstat, Is) ->
Inline = fun (#c_apply{op=#c_var{name={F,A}},args=As}=Call, Mod) ->
case find_inl(F, A, Is) of
#ifun{vars=Vs,body=B} ->
{#c_let{vars=Vs,
arg=kill_id_anns(core_lib:make_values(As)),
body=kill_id_anns(B)},
true}; %Have modified
_Other -> {Call,Mod}
end;
(Core, Mod) -> {Core,Mod}
end,
{F1,Mod} = cerl_trees:mapfold(Inline, false, F0),
Fstat#fstat{def={Name,F1},modified=Mod}.
weight_func(_Core, Acc) -> Acc + 1.
%% match_fail_fun() -> fun/1.
%% Return a function to use with map to fix inlineable functions
%% function_clause match_fail (if they have one).
match_fail_fun() ->
fun (#c_primop{anno=Anno0,name=#c_literal{val=match_fail}}=P) ->
Anno = keydelete(function_name, 1, Anno0),
P#c_primop{anno=Anno};
(Other) -> Other
end.
%% find_inl(Func, Arity, [Inline]) -> #ifun{} | no.
find_inl(F, A, [#ifun{func=F,arity=A}=If|_]) -> If;
find_inl(F, A, [_|Is]) -> find_inl(F, A, Is);
find_inl(_, _, []) -> no.
%% kill_id_anns(Body) -> Body'
kill_id_anns(Body) ->
cerl_trees:map(fun(#c_fun{anno=A0}=CFun) ->
A = kill_id_anns_1(A0),
CFun#c_fun{anno=A};
(Expr) ->
%% Mark everything as compiler generated to
%% suppress bogus warnings.
A = compiler_generated(cerl:get_ann(Expr)),
cerl:set_ann(Expr, A)
end, Body).
kill_id_anns_1([{'id',_}|As]) ->
kill_id_anns_1(As);
kill_id_anns_1([A|As]) ->
[A|kill_id_anns_1(As)];
kill_id_anns_1([]) -> [].
compiler_generated([compiler_generated|_]=Anno) ->
Anno;
compiler_generated(Anno) ->
[compiler_generated|Anno -- [compiler_generated]].
