%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 1999-2012. All Rights Reserved.
%%
%% The contents of this file are subject to the Erlang Public License,
%% Version 1.1, (the "License"); you may not use this file except in
%% compliance with the License. You should have received a copy of the
%% Erlang Public License along with this software. If not, it can be
%% retrieved online at http://www.erlang.org/.
%%
%% Software distributed under the License is distributed on an "AS IS"
%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
%% the License for the specific language governing rights and limitations
%% under the License.
%%
%% %CopyrightEnd%
%%
%% Purpose : Transform Core Erlang to Kernel Erlang
%% Kernel erlang is like Core Erlang with a few significant
%% differences:
%%
%% 1. It is flat! There are no nested calls or sub-blocks.
%%
%% 2. All variables are unique in a function. There is no scoping, or
%% rather the scope is the whole function.
%%
%% 3. Pattern matching (in cases and receives) has been compiled.
%%
%% 4. The annotations contain variable usages. Seeing we have to work
%% this out anyway for funs we might as well pass it on for free to
%% later passes.
%%
%% 5. All remote-calls are to statically named m:f/a. Meta-calls are
%% passed via erlang:apply/3.
%%
%% The translation is done in two passes:
%%
%% 1. Basic translation, translate variable/function names, flatten
%% completely, pattern matching compilation.
%%
%% 2. Fun-lifting (lambda-lifting), variable usage annotation and
%% last-call handling.
%%
%% All new Kexprs are created in the first pass, they are just
%% annotated in the second.
%%
%% Functions and BIFs
%%
%% Functions are "call"ed or "enter"ed if it is a last call, their
%% return values may be ignored. BIFs are things which are known to
%% be internal by the compiler and can only be called, their return
%% values cannot be ignored.
%%
%% Letrec's are handled rather naively. All the functions in one
%% letrec are handled as one block to find the free variables. While
%% this is not optimal it reflects how letrec's often are used. We
%% don't have to worry about variable shadowing and nested letrec's as
%% this is handled in the variable/function name translation. There
%% is a little bit of trickery to ensure letrec transformations fit
%% into the scheme of things.
%%
%% To ensure unique variable names we use a variable substitution
%% table and keep the set of all defined variables. The nested
%% scoping of Core means that we must also nest the substitution
%% tables, but the defined set must be passed through to match the
%% flat structure of Kernel and to make sure variables with the same
%% name from different scopes get different substitutions.
%%
%% We also use these substitutions to handle the variable renaming
%% necessary in pattern matching compilation.
%%
%% The pattern matching compilation assumes that the values of
%% different types don't overlap. This means that as there is no
%% character type yet in the machine all characters must be converted
%% to integers!
-module(v3_kernel).
-export([module/2,format_error/1]).
-import(lists, [map/2,foldl/3,foldr/3,mapfoldl/3,splitwith/2,member/2,
keymember/3,keyfind/3,partition/2]).
-import(ordsets, [add_element/2,del_element/2,union/2,union/1,subtract/2]).
-import(cerl, [c_tuple/1]).
-include("core_parse.hrl").
-include("v3_kernel.hrl").
%% These are not defined in v3_kernel.hrl.
get_kanno(Kthing) -> element(2, Kthing).
set_kanno(Kthing, Anno) -> setelement(2, Kthing, Anno).
copy_anno(Kdst, Ksrc) ->
Anno = get_kanno(Ksrc),
set_kanno(Kdst, Anno).
%% Internal kernel expressions and help functions.
%% N.B. the annotation field is ALWAYS the first field!
-record(ivalues, {anno=[],args}).
-record(ifun, {anno=[],vars,body}).
-record(iset, {anno=[],vars,arg,body}).
-record(iletrec, {anno=[],defs}).
-record(ialias, {anno=[],vars,pat}).
-record(iclause, {anno=[],isub,osub,pats,guard,body}).
-record(ireceive_accept, {anno=[],arg}).
-record(ireceive_next, {anno=[],arg}).
-type warning() :: term(). % XXX: REFINE
%% State record for kernel translator.
-record(kern, {func, %Current host function
ff, %Current function
vcount=0, %Variable counter
fcount=0, %Fun counter
ds=[], %Defined variables
funs=[], %Fun functions
free=[], %Free variables
ws=[] :: [warning()], %Warnings.
guard_refc=0}). %> 0 means in guard
-spec module(cerl:c_module(), [compile:option()]) ->
{'ok', #k_mdef{}, [warning()]}.
module(#c_module{anno=A,name=M,exports=Es,attrs=As,defs=Fs}, _Options) ->
Kas = attributes(As),
Kes = map(fun (#c_var{name={_,_}=Fname}) -> Fname end, Es),
St0 = #kern{},
{Kfs,St} = mapfoldl(fun function/2, St0, Fs),
{ok,#k_mdef{anno=A,name=M#c_literal.val,exports=Kes,attributes=Kas,
body=Kfs ++ St#kern.funs},lists:sort(St#kern.ws)}.
attributes([{#c_literal{val=Name},Val}|As]) ->
case include_attribute(Name) of
false ->
attributes(As);
true ->
[{Name,core_lib:literal_value(Val)}|attributes(As)]
end;
attributes([]) -> [].
include_attribute(type) -> false;
include_attribute(spec) -> false;
include_attribute(opaque) -> false;
include_attribute(export_type) -> false;
include_attribute(_) -> true.
function({#c_var{name={F,Arity}=FA},Body}, St0) ->
try
St1 = St0#kern{func=FA,ff=undefined,vcount=0,fcount=0,ds=sets:new()},
{#ifun{anno=Ab,vars=Kvs,body=B0},[],St2} = expr(Body, new_sub(), St1),
{B1,_,St3} = ubody(B0, return, St2),
%%B1 = B0, St3 = St2, %Null second pass
{#k_fdef{anno=#k{us=[],ns=[],a=Ab},
func=F,arity=Arity,vars=Kvs,body=B1},St3}
catch
Class:Error ->
Stack = erlang:get_stacktrace(),
io:fwrite("Function: ~w/~w\n", [F,Arity]),
erlang:raise(Class, Error, Stack)
end.
%% body(Cexpr, Sub, State) -> {Kexpr,[PreKepxr],State}.
%% Do the main sequence of a body. A body ends in an atomic value or
%% values. Must check if vector first so do expr.
body(#c_values{anno=A,es=Ces}, Sub, St0) ->
%% Do this here even if only in bodies.
{Kes,Pe,St1} = atomic_list(Ces, Sub, St0),
%%{Kes,Pe,St1} = expr_list(Ces, Sub, St0),
{#ivalues{anno=A,args=Kes},Pe,St1};
body(#ireceive_next{anno=A}, _, St) ->
{#k_receive_next{anno=A},[],St};
body(Ce, Sub, St0) ->
expr(Ce, Sub, St0).
%% guard(Cexpr, Sub, State) -> {Kexpr,State}.
%% We handle guards almost as bodies. The only special thing we
%% must do is to make the final Kexpr a #k_test{}.
%% Also, we wrap the entire guard in a try/catch which is
%% not strictly needed, but makes sure that every 'bif' instruction
%% will get a proper failure label.
guard(G0, Sub, St0) ->
{G1,St1} = wrap_guard(G0, St0),
{Ge0,Pre,St2} = expr(G1, Sub, St1),
{Ge,St} = gexpr_test(Ge0, St2),
{pre_seq(Pre, Ge),St}.
%% Wrap the entire guard in a try/catch if needed.
wrap_guard(#c_try{}=Try, St) -> {Try,St};
wrap_guard(Core, St0) ->
{VarName,St} = new_var_name(St0),
Var = #c_var{name=VarName},
Try = #c_try{arg=Core,vars=[Var],body=Var,evars=[],handler=#c_literal{val=false}},
{Try,St}.
%% gexpr_test(Kexpr, State) -> {Kexpr,State}.
%% Builds the final boolean test from the last Kexpr in a guard test.
%% Must enter try blocks and isets and find the last Kexpr in them.
%% This must end in a recognised BEAM test!
gexpr_test(#k_bif{anno=A,op=#k_remote{mod=#k_atom{val=erlang},
name=#k_atom{val=F},arity=Ar}=Op,
args=Kargs}=Ke, St) ->
%% Either convert to test if ok, or add test.
%% At this stage, erlang:float/1 is not a type test. (It should
%% have been converted to erlang:is_float/1.)
case erl_internal:new_type_test(F, Ar) orelse
erl_internal:comp_op(F, Ar) of
true -> {#k_test{anno=A,op=Op,args=Kargs},St};
false -> gexpr_test_add(Ke, St) %Add equality test
end;
gexpr_test(#k_try{arg=B0,vars=[#k_var{name=X}],body=#k_var{name=X},
handler=#k_atom{val=false}}=Try, St0) ->
{B,St} = gexpr_test(B0, St0),
%%ok = io:fwrite("~w: ~p~n", [?LINE,{B0,B}]),
{Try#k_try{arg=B},St};
gexpr_test(#iset{body=B0}=Iset, St0) ->
{B1,St1} = gexpr_test(B0, St0),
{Iset#iset{body=B1},St1};
gexpr_test(Ke, St) -> gexpr_test_add(Ke, St). %Add equality test
gexpr_test_add(Ke, St0) ->
Test = #k_remote{mod=#k_atom{val='erlang'},
name=#k_atom{val='=:='},
arity=2},
{Ae,Ap,St1} = force_atomic(Ke, St0),
{pre_seq(Ap, #k_test{anno=get_kanno(Ke),
op=Test,args=[Ae,#k_atom{val='true'}]}),St1}.
%% expr(Cexpr, Sub, State) -> {Kexpr,[PreKexpr],State}.
%% Convert a Core expression, flattening it at the same time.
expr(#c_var{anno=A,name={_Name,Arity}}=Fname, Sub, St) ->
%% A local in an expression.
%% For now, these are wrapped into a fun by reverse
%% etha-conversion, but really, there should be exactly one
%% such "lambda function" for each escaping local name,
%% instead of one for each occurrence as done now.
Vs = [#c_var{name=list_to_atom("V" ++ integer_to_list(V))} ||
V <- integers(1, Arity)],
Fun = #c_fun{anno=A,vars=Vs,body=#c_apply{anno=A,op=Fname,args=Vs}},
expr(Fun, Sub, St);
expr(#c_var{anno=A,name=V}, Sub, St) ->
{#k_var{anno=A,name=get_vsub(V, Sub)},[],St};
expr(#c_literal{anno=A,val=V}, _Sub, St) ->
Klit = case V of
[] ->
#k_nil{anno=A};
V when is_integer(V) ->
#k_int{anno=A,val=V};
V when is_float(V) ->
#k_float{anno=A,val=V};
V when is_atom(V) ->
#k_atom{anno=A,val=V};
_ ->
#k_literal{anno=A,val=V}
end,
{Klit,[],St};
expr(#c_cons{anno=A,hd=Ch,tl=Ct}, Sub, St0) ->
%% Do cons in two steps, first the expressions left to right, then
%% any remaining literals right to left.
{Kh0,Hp0,St1} = expr(Ch, Sub, St0),
{Kt0,Tp0,St2} = expr(Ct, Sub, St1),
{Kt1,Tp1,St3} = force_atomic(Kt0, St2),
{Kh1,Hp1,St4} = force_atomic(Kh0, St3),
{#k_cons{anno=A,hd=Kh1,tl=Kt1},Hp0 ++ Tp0 ++ Tp1 ++ Hp1,St4};
expr(#c_tuple{anno=A,es=Ces}, Sub, St0) ->
{Kes,Ep,St1} = atomic_list(Ces, Sub, St0),
{#k_tuple{anno=A,es=Kes},Ep,St1};
expr(#c_binary{anno=A,segments=Cv}, Sub, St0) ->
try atomic_bin(Cv, Sub, St0) of
{Kv,Ep,St1} ->
{#k_binary{anno=A,segs=Kv},Ep,St1}
catch
throw:bad_element_size ->
St1 = add_warning(get_line(A), bad_segment_size, A, St0),
Erl = #c_literal{val=erlang},
Name = #c_literal{val=error},
Args = [#c_literal{val=badarg}],
Error = #c_call{anno=A,module=Erl,name=Name,args=Args},
expr(Error, Sub, St1)
end;
expr(#c_fun{anno=A,vars=Cvs,body=Cb}, Sub0, #kern{ff=OldFF,func=Func}=St0) ->
FA = case OldFF of
undefined ->
Func;
_ ->
case lists:keyfind(id, 1, A) of
{id,{_,_,Name}} -> Name;
_ ->
case lists:keyfind(letrec_name, 1, A) of
{letrec_name,Name} -> Name;
_ -> unknown_fun
end
end
end,
{Kvs,Sub1,St1} = pattern_list(Cvs, Sub0, St0#kern{ff=FA}),
%%ok = io:fwrite("~w: ~p~n", [?LINE,{{Cvs,Sub0,St0},{Kvs,Sub1,St1}}]),
{Kb,Pb,St2} = body(Cb, Sub1, St1#kern{ff=FA}),
{#ifun{anno=A,vars=Kvs,body=pre_seq(Pb, Kb)},[],St2#kern{ff=OldFF}};
expr(#c_seq{arg=Ca,body=Cb}, Sub, St0) ->
{Ka,Pa,St1} = body(Ca, Sub, St0),
{Kb,Pb,St2} = body(Cb, Sub, St1),
{Kb,Pa ++ [Ka] ++ Pb,St2};
expr(#c_let{anno=A,vars=Cvs,arg=Ca,body=Cb}, Sub0, St0) ->
%%ok = io:fwrite("~w: ~p~n", [?LINE,{Cvs,Sub0,St0}]),
{Ka,Pa,St1} = body(Ca, Sub0, St0),
{Kps,Sub1,St2} = pattern_list(Cvs, Sub0, St1),
%%ok = io:fwrite("~w: ~p~n", [?LINE,{Kps,Sub1,St1,St2}]),
%% Break known multiple values into separate sets.
Sets = case Ka of
#ivalues{args=Kas} ->
foldr2(fun (V, Val, Sb) ->
[#iset{vars=[V],arg=Val}|Sb] end,
[], Kps, Kas);
_Other ->
[#iset{anno=A,vars=Kps,arg=Ka}]
end,
{Kb,Pb,St3} = body(Cb, Sub1, St2),
{Kb,Pa ++ Sets ++ Pb,St3};
expr(#c_letrec{anno=A,defs=Cfs,body=Cb}, Sub0, St0) ->
%% Make new function names and store substitution.
{Fs0,{Sub1,St1}} =
mapfoldl(fun ({#c_var{name={F,Ar}},B0}, {Sub,S0}) ->
{N,St1} = new_fun_name(atom_to_list(F)
++ "/" ++
integer_to_list(Ar),
S0),
B = set_kanno(B0, [{letrec_name,N}]),
{{N,B},{set_fsub(F, Ar, N, Sub),St1}}
end, {Sub0,St0}, Cfs),
%% Run translation on functions and body.
{Fs1,St2} = mapfoldl(fun ({N,Fd0}, S1) ->
{Fd1,[],St2} = expr(Fd0, Sub1, S1#kern{ff=N}),
Fd = set_kanno(Fd1, A),
{{N,Fd},St2}
end, St1, Fs0),
{Kb,Pb,St3} = body(Cb, Sub1, St2#kern{ff=St1#kern.ff}),
{Kb,[#iletrec{anno=A,defs=Fs1}|Pb],St3};
expr(#c_case{arg=Ca,clauses=Ccs}, Sub, St0) ->
{Ka,Pa,St1} = body(Ca, Sub, St0), %This is a body!
{Kvs,Pv,St2} = match_vars(Ka, St1), %Must have variables here!
{Km,St3} = kmatch(Kvs, Ccs, Sub, St2),
Match = flatten_seq(build_match(Kvs, Km)),
{last(Match),Pa ++ Pv ++ first(Match),St3};
expr(#c_receive{anno=A,clauses=Ccs0,timeout=Ce,action=Ca}, Sub, St0) ->
{Ke,Pe,St1} = atomic(Ce, Sub, St0), %Force this to be atomic!
{Rvar,St2} = new_var(St1),
%% Need to massage accept clauses and add reject clause before matching.
Ccs1 = map(fun (#c_clause{anno=Banno,body=B0}=C) ->
B1 = #c_seq{arg=#ireceive_accept{anno=A},body=B0},
C#c_clause{anno=Banno,body=B1}
end, Ccs0),
{Mpat,St3} = new_var_name(St2),
Rc = #c_clause{anno=[compiler_generated|A],
pats=[#c_var{name=Mpat}],guard=#c_literal{anno=A,val=true},
body=#ireceive_next{anno=A}},
{Km,St4} = kmatch([Rvar], Ccs1 ++ [Rc], Sub, add_var_def(Rvar, St3)),
{Ka,Pa,St5} = body(Ca, Sub, St4),
{#k_receive{anno=A,var=Rvar,body=Km,timeout=Ke,action=pre_seq(Pa, Ka)},
Pe,St5};
expr(#c_apply{anno=A,op=Cop,args=Cargs}, Sub, St) ->
c_apply(A, Cop, Cargs, Sub, St);
expr(#c_call{anno=A,module=#c_literal{val=erlang},name=#c_literal{val=is_record},
args=[_,Tag,Sz]=Args0}, Sub, St0) ->
{Args,Ap,St} = atomic_list(Args0, Sub, St0),
Remote = #k_remote{mod=#k_atom{val=erlang},name=#k_atom{val=is_record},arity=3},
case {Tag,Sz} of
{#c_literal{val=Atom},#c_literal{val=Int}}
when is_atom(Atom), is_integer(Int) ->
%% Tag and size are literals. Make it a BIF, which will actually
%% be expanded out in a later pass.
{#k_bif{anno=A,op=Remote,args=Args},Ap,St};
{_,_} ->
%% (Only in bodies.) Make it into an actual call to the BIF.
{#k_call{anno=A,op=Remote,args=Args},Ap,St}
end;
expr(#c_call{anno=A,module=M0,name=F0,args=Cargs}, Sub, St0) ->
Ar = length(Cargs),
{Type,St1} = case call_type(M0, F0, Ar) of
error ->
%% Invalid call (e.g. M:42/3). Issue a warning,
%% and let the generated code use the old explict apply.
{old_apply,add_warning(get_line(A), bad_call, A, St0)};
Type0 ->
{Type0,St0}
end,
case Type of
old_apply ->
Call = #c_call{anno=A,
module=#c_literal{val=erlang},
name=#c_literal{val=apply},
args=[M0,F0,make_list(Cargs)]},
expr(Call, Sub, St1);
_ ->
{[M1,F1|Kargs],Ap,St} = atomic_list([M0,F0|Cargs], Sub, St1),
Call = case Type of
bif ->
#k_bif{anno=A,op=#k_remote{mod=M1,name=F1,arity=Ar},
args=Kargs};
call ->
#k_call{anno=A,op=#k_remote{mod=M1,name=F1,arity=Ar},
args=Kargs};
apply ->
#k_call{anno=A,op=#k_remote{mod=M1,name=F1,arity=Ar},
args=Kargs}
end,
{Call,Ap,St}
end;
expr(#c_primop{anno=A,name=#c_literal{val=match_fail},args=Cargs0}, Sub, St0) ->
Cargs = translate_match_fail(Cargs0, Sub, A, St0),
{Kargs,Ap,St} = atomic_list(Cargs, Sub, St0),
Ar = length(Cargs),
Call = #k_call{anno=A,op=#k_remote{mod=#k_atom{val=erlang},
name=#k_atom{val=error},
arity=Ar},args=Kargs},
{Call,Ap,St};
expr(#c_primop{anno=A,name=#c_literal{val=N},args=Cargs}, Sub, St0) ->
{Kargs,Ap,St1} = atomic_list(Cargs, Sub, St0),
Ar = length(Cargs),
{#k_bif{anno=A,op=#k_internal{name=N,arity=Ar},args=Kargs},Ap,St1};
expr(#c_try{anno=A,arg=Ca,vars=Cvs,body=Cb,evars=Evs,handler=Ch}, Sub0, St0) ->
%% The normal try expression. The body and exception handler
%% variables behave as let variables.
{Ka,Pa,St1} = body(Ca, Sub0, St0),
{Kcvs,Sub1,St2} = pattern_list(Cvs, Sub0, St1),
{Kb,Pb,St3} = body(Cb, Sub1, St2),
{Kevs,Sub2,St4} = pattern_list(Evs, Sub0, St3),
{Kh,Ph,St5} = body(Ch, Sub2, St4),
{#k_try{anno=A,arg=pre_seq(Pa, Ka),
vars=Kcvs,body=pre_seq(Pb, Kb),
evars=Kevs,handler=pre_seq(Ph, Kh)},[],St5};
expr(#c_catch{anno=A,body=Cb}, Sub, St0) ->
{Kb,Pb,St1} = body(Cb, Sub, St0),
{#k_catch{anno=A,body=pre_seq(Pb, Kb)},[],St1};
%% Handle internal expressions.
expr(#ireceive_accept{anno=A}, _Sub, St) -> {#k_receive_accept{anno=A},[],St}.
%% Translate a function_clause exception to a case_clause exception if
%% it has been moved into another function. (A function_clause exception
%% will not work correctly if it is moved into another function, or
%% even if it is invoked not from the top level in the correct function.)
translate_match_fail(Args, Sub, Anno, St) ->
case Args of
[#c_tuple{es=[#c_literal{val=function_clause}|As]}] ->
translate_match_fail_1(Anno, As, Sub, St);
[#c_literal{val=Tuple}] when is_tuple(Tuple) ->
%% The inliner may have created a literal out of
%% the original #c_tuple{}.
case tuple_to_list(Tuple) of
[function_clause|As0] ->
As = [#c_literal{val=E} || E <- As0],
translate_match_fail_1(Anno, As, Sub, St);
_ ->
Args
end;
_ ->
%% Not a function_clause exception.
Args
end.
translate_match_fail_1(Anno, As, Sub, #kern{ff=FF}) ->
AnnoFunc = case keyfind(function_name, 1, Anno) of
false ->
none; %Force rewrite.
{function_name,{Name,Arity}} ->
{get_fsub(Name, Arity, Sub),Arity}
end,
case {AnnoFunc,FF} of
{Same,Same} ->
%% Still in the correct function.
translate_fc(As);
{{F,_},F} ->
%% Still in the correct function.
translate_fc(As);
_ ->
%% Wrong function or no function_name annotation.
%%
%% The inliner has copied the match_fail(function_clause)
%% primop from another function (or from another instance of
%% the current function). match_fail(function_clause) will
%% only work at the top level of the function it was originally
%% defined in, so we will need to rewrite it to a case_clause.
[c_tuple([#c_literal{val=case_clause},c_tuple(As)])]
end.
translate_fc(Args) ->
[#c_literal{val=function_clause},make_list(Args)].
%% call_type(Module, Function, Arity) -> call | bif | apply | error.
%% Classify the call.
call_type(#c_literal{val=M}, #c_literal{val=F}, Ar) when is_atom(M), is_atom(F) ->
case is_remote_bif(M, F, Ar) of
false -> call;
true -> bif
end;
call_type(#c_var{}, #c_literal{val=A}, _) when is_atom(A) -> apply;
call_type(#c_literal{val=A}, #c_var{}, _) when is_atom(A) -> apply;
call_type(#c_var{}, #c_var{}, _) -> apply;
call_type(_, _, _) -> error.
%% match_vars(Kexpr, State) -> {[Kvar],[PreKexpr],State}.
%% Force return from body into a list of variables.
match_vars(#ivalues{args=As}, St) ->
foldr(fun (Ka, {Vs,Vsp,St0}) ->
{V,Vp,St1} = force_variable(Ka, St0),
{[V|Vs],Vp ++ Vsp,St1}
end, {[],[],St}, As);
match_vars(Ka, St0) ->
{V,Vp,St1} = force_variable(Ka, St0),
{[V],Vp,St1}.
%% c_apply(A, Op, [Carg], Sub, State) -> {Kexpr,[PreKexpr],State}.
%% Transform application, detect which are guaranteed to be bifs.
c_apply(A, #c_var{anno=Ra,name={F0,Ar}}, Cargs, Sub, St0) ->
{Kargs,Ap,St1} = atomic_list(Cargs, Sub, St0),
F1 = get_fsub(F0, Ar, Sub), %Has it been rewritten
{#k_call{anno=A,op=#k_local{anno=Ra,name=F1,arity=Ar},args=Kargs},
Ap,St1};
c_apply(A, Cop, Cargs, Sub, St0) ->
{Kop,Op,St1} = variable(Cop, Sub, St0),
{Kargs,Ap,St2} = atomic_list(Cargs, Sub, St1),
{#k_call{anno=A,op=Kop,args=Kargs},Op ++ Ap,St2}.
flatten_seq(#iset{anno=A,vars=Vs,arg=Arg,body=B}) ->
[#iset{anno=A,vars=Vs,arg=Arg}|flatten_seq(B)];
flatten_seq(Ke) -> [Ke].
pre_seq([#iset{anno=A,vars=Vs,arg=Arg,body=B}|Ps], K) ->
B = undefined, %Assertion.
#iset{anno=A,vars=Vs,arg=Arg,body=pre_seq(Ps, K)};
pre_seq([P|Ps], K) ->
#iset{vars=[],arg=P,body=pre_seq(Ps, K)};
pre_seq([], K) -> K.
%% atomic(Cexpr, Sub, State) -> {Katomic,[PreKexpr],State}.
%% Convert a Core expression making sure the result is an atomic
%% literal.
atomic(Ce, Sub, St0) ->
{Ke,Kp,St1} = expr(Ce, Sub, St0),
{Ka,Ap,St2} = force_atomic(Ke, St1),
{Ka,Kp ++ Ap,St2}.
force_atomic(Ke, St0) ->
case is_atomic(Ke) of
true -> {Ke,[],St0};
false ->
{V,St1} = new_var(St0),
{V,[#iset{vars=[V],arg=Ke}],St1}
end.
% force_atomic_list(Kes, St) ->
% foldr(fun (Ka, {As,Asp,St0}) ->
% {A,Ap,St1} = force_atomic(Ka, St0),
% {[A|As],Ap ++ Asp,St1}
% end, {[],[],St}, Kes).
atomic_bin([#c_bitstr{anno=A,val=E0,size=S0,unit=U0,type=T,flags=Fs0}|Es0],
Sub, St0) ->
{E,Ap1,St1} = atomic(E0, Sub, St0),
{S1,Ap2,St2} = atomic(S0, Sub, St1),
validate_bin_element_size(S1),
U1 = core_lib:literal_value(U0),
Fs1 = core_lib:literal_value(Fs0),
{Es,Ap3,St3} = atomic_bin(Es0, Sub, St2),
{#k_bin_seg{anno=A,size=S1,
unit=U1,
type=core_lib:literal_value(T),
flags=Fs1,
seg=E,next=Es},
Ap1++Ap2++Ap3,St3};
atomic_bin([], _Sub, St) -> {#k_bin_end{},[],St}.
validate_bin_element_size(#k_var{}) -> ok;
validate_bin_element_size(#k_int{val=V}) when V >= 0 -> ok;
validate_bin_element_size(#k_atom{val=all}) -> ok;
validate_bin_element_size(#k_atom{val=undefined}) -> ok;
validate_bin_element_size(_) -> throw(bad_element_size).
%% atomic_list([Cexpr], Sub, State) -> {[Kexpr],[PreKexpr],State}.
atomic_list(Ces, Sub, St) ->
foldr(fun (Ce, {Kes,Esp,St0}) ->
{Ke,Ep,St1} = atomic(Ce, Sub, St0),
{[Ke|Kes],Ep ++ Esp,St1}
end, {[],[],St}, Ces).
%% is_atomic(Kexpr) -> boolean().
%% Is a Kexpr atomic? Strings are NOT considered atomic!
is_atomic(#k_literal{}) -> true;
is_atomic(#k_int{}) -> true;
is_atomic(#k_float{}) -> true;
is_atomic(#k_atom{}) -> true;
%%is_atomic(#k_char{}) -> true; %No characters
is_atomic(#k_nil{}) -> true;
is_atomic(#k_var{}) -> true;
is_atomic(_) -> false.
%% variable(Cexpr, Sub, State) -> {Kvar,[PreKexpr],State}.
%% Convert a Core expression making sure the result is a variable.
variable(Ce, Sub, St0) ->
{Ke,Kp,St1} = expr(Ce, Sub, St0),
{Kv,Vp,St2} = force_variable(Ke, St1),
{Kv,Kp ++ Vp,St2}.
force_variable(#k_var{}=Ke, St) -> {Ke,[],St};
force_variable(Ke, St0) ->
{V,St1} = new_var(St0),
{V,[#iset{vars=[V],arg=Ke}],St1}.
%% pattern(Cpat, Isub, Osub, State) -> {Kpat,Sub,State}.
%% Convert patterns. Variables shadow so rename variables that are
%% already defined.
%%
%% Patterns are complicated by sizes in binaries. These are pure
%% input variables which create no bindings. We, therefore, need to
%% carry around the original substitutions to get the correct
%% handling.
pattern(#c_var{anno=A,name=V}, _Isub, Osub, St0) ->
case sets:is_element(V, St0#kern.ds) of
true ->
{New,St1} = new_var_name(St0),
{#k_var{anno=A,name=New},
set_vsub(V, New, Osub),
St1#kern{ds=sets:add_element(New, St1#kern.ds)}};
false ->
{#k_var{anno=A,name=V},Osub,
St0#kern{ds=sets:add_element(V, St0#kern.ds)}}
end;
pattern(#c_literal{anno=A,val=Val}, _Isub, Osub, St) ->
{#k_literal{anno=A,val=Val},Osub,St};
pattern(#c_cons{anno=A,hd=Ch,tl=Ct}, Isub, Osub0, St0) ->
{Kh,Osub1,St1} = pattern(Ch, Isub, Osub0, St0),
{Kt,Osub2,St2} = pattern(Ct, Isub, Osub1, St1),
{#k_cons{anno=A,hd=Kh,tl=Kt},Osub2,St2};
pattern(#c_tuple{anno=A,es=Ces}, Isub, Osub0, St0) ->
{Kes,Osub1,St1} = pattern_list(Ces, Isub, Osub0, St0),
{#k_tuple{anno=A,es=Kes},Osub1,St1};
pattern(#c_binary{anno=A,segments=Cv}, Isub, Osub0, St0) ->
{Kv,Osub1,St1} = pattern_bin(Cv, Isub, Osub0, St0),
{#k_binary{anno=A,segs=Kv},Osub1,St1};
pattern(#c_alias{anno=A,var=Cv,pat=Cp}, Isub, Osub0, St0) ->
{Cvs,Cpat} = flatten_alias(Cp),
{Kvs,Osub1,St1} = pattern_list([Cv|Cvs], Isub, Osub0, St0),
{Kpat,Osub2,St2} = pattern(Cpat, Isub, Osub1, St1),
{#ialias{anno=A,vars=Kvs,pat=Kpat},Osub2,St2}.
flatten_alias(#c_alias{var=V,pat=P}) ->
{Vs,Pat} = flatten_alias(P),
{[V|Vs],Pat};
flatten_alias(Pat) -> {[],Pat}.
pattern_bin(Es, Isub, Osub0, St0) ->
{Kbin,{_,Osub},St} = pattern_bin_1(Es, Isub, Osub0, St0),
{Kbin,Osub,St}.
pattern_bin_1([#c_bitstr{anno=A,val=E0,size=S0,unit=U,type=T,flags=Fs}|Es0],
Isub0, Osub0, St0) ->
{S1,[],St1} = expr(S0, Isub0, St0),
S = case S1 of
#k_int{} -> S1;
#k_var{} -> S1;
#k_atom{} -> S1;
_ ->
%% Bad size (coming from an optimization or Core Erlang
%% source code) - replace it with a known atom because
%% a literal or bit syntax construction can cause further
%% problems.
#k_atom{val=bad_size}
end,
U0 = core_lib:literal_value(U),
Fs0 = core_lib:literal_value(Fs),
%%ok= io:fwrite("~w: ~p~n", [?LINE,{B0,S,U0,Fs0}]),
{E,Osub1,St2} = pattern(E0, Isub0, Osub0, St1),
Isub1 = case E0 of
#c_var{name=V} ->
set_vsub(V, E#k_var.name, Isub0);
_ -> Isub0
end,
{Es,{Isub,Osub},St3} = pattern_bin_1(Es0, Isub1, Osub1, St2),
{#k_bin_seg{anno=A,size=S,
unit=U0,
type=core_lib:literal_value(T),
flags=Fs0,
seg=E,next=Es},
{Isub,Osub},St3};
pattern_bin_1([], Isub, Osub, St) -> {#k_bin_end{},{Isub,Osub},St}.
%% pattern_list([Cexpr], Sub, State) -> {[Kexpr],Sub,State}.
pattern_list(Ces, Sub, St) ->
pattern_list(Ces, Sub, Sub, St).
pattern_list(Ces, Isub, Osub, St) ->
foldr(fun (Ce, {Kes,Osub0,St0}) ->
{Ke,Osub1,St1} = pattern(Ce, Isub, Osub0, St0),
{[Ke|Kes],Osub1,St1}
end, {[],Osub,St}, Ces).
%% new_sub() -> Subs.
%% set_vsub(Name, Sub, Subs) -> Subs.
%% subst_vsub(Name, Sub, Subs) -> Subs.
%% get_vsub(Name, Subs) -> SubName.
%% Add/get substitute Sub for Name to VarSub. Use orddict so we know
%% the format is a list {Name,Sub} pairs. When adding a new
%% substitute we fold substitute chains so we never have to search
%% more than once.
new_sub() -> orddict:new().
get_vsub(V, Vsub) ->
case orddict:find(V, Vsub) of
{ok,Val} -> Val;
error -> V
end.
set_vsub(V, S, Vsub) ->
orddict:store(V, S, Vsub).
subst_vsub(V, S, Vsub0) ->
%% Fold chained substitutions.
Vsub1 = orddict:map(fun (_, V1) when V1 =:= V -> S;
(_, V1) -> V1
end, Vsub0),
orddict:store(V, S, Vsub1).
get_fsub(F, A, Fsub) ->
case orddict:find({F,A}, Fsub) of
{ok,Val} -> Val;
error -> F
end.
set_fsub(F, A, S, Fsub) ->
orddict:store({F,A}, S, Fsub).
new_fun_name(St) ->
new_fun_name("anonymous", St).
%% new_fun_name(Type, State) -> {FunName,State}.
new_fun_name(Type, #kern{func={F,Arity},fcount=C}=St) ->
Name = "-" ++ atom_to_list(F) ++ "/" ++ integer_to_list(Arity) ++
"-" ++ Type ++ "-" ++ integer_to_list(C) ++ "-",
{list_to_atom(Name),St#kern{fcount=C+1}}.
%% new_var_name(State) -> {VarName,State}.
new_var_name(#kern{vcount=C}=St) ->
{list_to_atom("ker" ++ integer_to_list(C)),St#kern{vcount=C+1}}.
%% new_var(State) -> {#k_var{},State}.
new_var(St0) ->
{New,St1} = new_var_name(St0),
{#k_var{name=New},St1}.
%% new_vars(Count, State) -> {[#k_var{}],State}.
%% Make Count new variables.
new_vars(N, St) -> new_vars(N, St, []).
new_vars(N, St0, Vs) when N > 0 ->
{V,St1} = new_var(St0),
new_vars(N-1, St1, [V|Vs]);
new_vars(0, St, Vs) -> {Vs,St}.
make_vars(Vs) -> [ #k_var{name=V} || V <- Vs ].
add_var_def(V, St) ->
St#kern{ds=sets:add_element(V#k_var.name, St#kern.ds)}.
%%add_vars_def(Vs, St) ->
%% Ds = foldl(fun (#k_var{name=V}, Ds) -> add_element(V, Ds) end,
%% St#kern.ds, Vs),
%% St#kern{ds=Ds}.
%% is_remote_bif(Mod, Name, Arity) -> true | false.
%% Test if function is really a BIF.
is_remote_bif(erlang, get, 1) -> true;
is_remote_bif(erlang, N, A) ->
case erl_internal:guard_bif(N, A) of
true -> true;
false ->
try erl_internal:op_type(N, A) of
arith -> true;
bool -> true;
comp -> true;
list -> false;
send -> false
catch
_:_ -> false % not an op
end
end;
is_remote_bif(_, _, _) -> false.
%% bif_vals(Name, Arity) -> integer().
%% bif_vals(Mod, Name, Arity) -> integer().
%% Determine how many return values a BIF has. Provision for BIFs to
%% return multiple values. Only used in bodies where a BIF may be
%% called for effect only.
bif_vals(dsetelement, 3) -> 0;
bif_vals(bs_context_to_binary, 1) -> 0;
bif_vals(_, _) -> 1.
bif_vals(_, _, _) -> 1.
%% foldr2(Fun, Acc, List1, List2) -> Acc.
%% Fold over two lists.
foldr2(Fun, Acc0, [E1|L1], [E2|L2]) ->
Acc1 = Fun(E1, E2, Acc0),
foldr2(Fun, Acc1, L1, L2);
foldr2(_, Acc, [], []) -> Acc.
%% first([A]) -> [A].
%% last([A]) -> A.
last([L]) -> L;
last([_|T]) -> last(T).
first([_]) -> [];
first([H|T]) -> [H|first(T)].
%% This code implements the algorithm for an optimizing compiler for
%% pattern matching given "The Implementation of Functional
%% Programming Languages" by Simon Peyton Jones. The code is much
%% longer as the meaning of constructors is different from the book.
%%
%% In Erlang many constructors can have different values, e.g. 'atom'
%% or 'integer', whereas in the original algorithm thse would be
%% different constructors. Our view makes it easier in later passes to
%% handle indexing over each type.
%%
%% Patterns are complicated by having alias variables. The form of a
%% pattern is Pat | {alias,Pat,[AliasVar]}. This is hidden by access
%% functions to pattern arguments but the code must be aware of it.
%%
%% The compilation proceeds in two steps:
%%
%% 1. The patterns in the clauses to converted to lists of kernel
%% patterns. The Core clause is now hybrid, this is easier to work
%% with. Remove clauses with trivially false guards, this simplifies
%% later passes. Add locally defined vars and variable subs to each
%% clause for later use.
%%
%% 2. The pattern matching is optimised. Variable substitutions are
%% added to the VarSub structure and new variables are made visible.
%% The guard and body are then converted to Kernel form.
%% kmatch([Var], [Clause], Sub, State) -> {Kexpr,State}.
kmatch(Us, Ccs, Sub, St0) ->
{Cs,St1} = match_pre(Ccs, Sub, St0), %Convert clauses
Def = fail,
%% Def = #k_call{anno=[compiler_generated],
%% op=#k_remote{mod=#k_atom{val=erlang},
%% name=#k_atom{val=exit},
%% arity=1},
%% args=[#k_atom{val=kernel_match_error}]},
match(Us, Cs, Def, St1). %Do the match.
%% match_pre([Cclause], Sub, State) -> {[Clause],State}.
%% Must be careful not to generate new substitutions here now!
%% Remove clauses with trivially false guards which will never
%% succeed.
match_pre(Cs, Sub0, St) ->
foldr(fun (#c_clause{anno=A,pats=Ps,guard=G,body=B}, {Cs0,St0}) ->
{Kps,Osub1,St1} = pattern_list(Ps, Sub0, St0),
{[#iclause{anno=A,isub=Sub0,osub=Osub1,
pats=Kps,guard=G,body=B}|
Cs0],St1}
end, {[],St}, Cs).
%% match([Var], [Clause], Default, State) -> {MatchExpr,State}.
match([_U|_Us] = L, Cs, Def, St0) ->
%%ok = io:format("match ~p~n", [Cs]),
Pcss = partition(Cs),
foldr(fun (Pcs, {D,St}) -> match_varcon(L, Pcs, D, St) end,
{Def,St0}, Pcss);
match([], Cs, Def, St) ->
match_guard(Cs, Def, St).
%% match_guard([Clause], Default, State) -> {IfExpr,State}.
%% Build a guard to handle guards. A guard *ALWAYS* fails if no
%% clause matches, there will be a surrounding 'alt' to catch the
%% failure. Drop redundant cases, i.e. those after a true guard.
match_guard(Cs0, Def0, St0) ->
{Cs1,Def1,St1} = match_guard_1(Cs0, Def0, St0),
{build_alt(build_guard(Cs1), Def1),St1}.
match_guard_1([#iclause{anno=A,osub=Osub,guard=G,body=B}|Cs0], Def0, St0) ->
case is_true_guard(G) of
true ->
%% The true clause body becomes the default.
{Kb,Pb,St1} = body(B, Osub, St0),
St2 = maybe_add_warning(Cs0, A, St1),
St = maybe_add_warning(Def0, A, St2),
{[],pre_seq(Pb, Kb),St};
false ->
{Kg,St1} = guard(G, Osub, St0),
{Kb,Pb,St2} = body(B, Osub, St1),
{Cs1,Def1,St3} = match_guard_1(Cs0, Def0, St2),
{[#k_guard_clause{guard=Kg,body=pre_seq(Pb, Kb)}|Cs1],
Def1,St3}
end;
match_guard_1([], Def, St) -> {[],Def,St}.
maybe_add_warning([C|_], MatchAnno, St) ->
maybe_add_warning(C, MatchAnno, St);
maybe_add_warning([], _MatchAnno, St) -> St;
maybe_add_warning(fail, _MatchAnno, St) -> St;
maybe_add_warning(Ke, MatchAnno, St) ->
case is_compiler_generated(Ke) of
true ->
St;
false ->
Anno = get_kanno(Ke),
Line = get_line(Anno),
MatchLine = get_line(MatchAnno),
Warn = case MatchLine of
none -> nomatch_shadow;
_ -> {nomatch_shadow,MatchLine}
end,
add_warning(Line, Warn, Anno, St)
end.
get_line([Line|_]) when is_integer(Line) -> Line;
get_line([_|T]) -> get_line(T);
get_line([]) -> none.
get_file([{file,File}|_]) -> File;
get_file([_|T]) -> get_file(T);
get_file([]) -> "no_file". % should not happen
%% is_true_guard(Guard) -> boolean().
%% Test if a guard is trivially true.
is_true_guard(#c_literal{val=true}) -> true;
is_true_guard(_) -> false.
%% partition([Clause]) -> [[Clause]].
%% Partition a list of clauses into groups which either contain
%% clauses with a variable first argument, or with a "constructor".
partition([C1|Cs]) ->
V1 = is_var_clause(C1),
{More,Rest} = splitwith(fun (C) -> is_var_clause(C) =:= V1 end, Cs),
[[C1|More]|partition(Rest)];
partition([]) -> [].
%% match_varcon([Var], [Clause], Def, [Var], Sub, State) ->
%% {MatchExpr,State}.
match_varcon(Us, [C|_]=Cs, Def, St) ->
case is_var_clause(C) of
true -> match_var(Us, Cs, Def, St);
false -> match_con(Us, Cs, Def, St)
end.
%% match_var([Var], [Clause], Def, State) -> {MatchExpr,State}.
%% Build a call to "select" from a list of clauses all containing a
%% variable as the first argument. We must rename the variable in
%% each clause to be the match variable as these clause will share
%% this variable and may have different names for it. Rename aliases
%% as well.
match_var([U|Us], Cs0, Def, St) ->
Cs1 = map(fun (#iclause{isub=Isub0,osub=Osub0,pats=[Arg|As]}=C) ->
Vs = [arg_arg(Arg)|arg_alias(Arg)],
Osub1 = foldl(fun (#k_var{name=V}, Acc) ->
subst_vsub(V, U#k_var.name, Acc)
end, Osub0, Vs),
Isub1 = foldl(fun (#k_var{name=V}, Acc) ->
subst_vsub(V, U#k_var.name, Acc)
end, Isub0, Vs),
C#iclause{isub=Isub1,osub=Osub1,pats=As}
end, Cs0),
match(Us, Cs1, Def, St).
%% match_con(Variables, [Clause], Default, State) -> {SelectExpr,State}.
%% Build call to "select" from a list of clauses all containing a
%% constructor/constant as first argument. Group the constructors
%% according to type, the order is really irrelevant but tries to be
%% smart.
match_con(Us, [C], Def, St) ->
%% There is only one clause. We can keep literal tuples and
%% lists, but we must convert []/integer/float/atom literals
%% to the proper record (#k_nil{} and so on).
Cs = [expand_pat_lit_clause(C, false)],
match_con_1(Us, Cs, Def, St);
match_con(Us, Cs0, Def, St) ->
%% More than one clause. Remove literals at the top level.
Cs = [expand_pat_lit_clause(C, true) || C <- Cs0],
match_con_1(Us, Cs, Def, St).
match_con_1([U|_Us] = L, Cs, Def, St0) ->
%% Extract clauses for different constructors (types).
%%ok = io:format("match_con ~p~n", [Cs]),
Ttcs = select_types([k_binary], Cs) ++ select_bin_con(Cs) ++
select_types([k_cons,k_tuple,k_atom,k_float,k_int,k_nil,k_literal], Cs),
%%ok = io:format("ttcs = ~p~n", [Ttcs]),
{Scs,St1} =
mapfoldl(fun ({T,Tcs}, St) ->
{[S|_]=Sc,S1} = match_value(L, T, Tcs, fail, St),
%%ok = io:format("match_con type2 ~p~n", [T]),
Anno = get_kanno(S),
{#k_type_clause{anno=Anno,type=T,values=Sc},S1} end,
St0, Ttcs),
{build_alt_1st_no_fail(build_select(U, Scs), Def),St1}.
select_types(Types, Cs) ->
[{T,Tcs} || T <- Types, begin Tcs = select(T, Cs), Tcs =/= [] end].
expand_pat_lit_clause(#iclause{pats=[#ialias{pat=#k_literal{anno=A,val=Val}}=Alias|Ps]}=C, B) ->
P = case B of
true -> expand_pat_lit(Val, A);
false -> literal(Val, A)
end,
C#iclause{pats=[Alias#ialias{pat=P}|Ps]};
expand_pat_lit_clause(#iclause{pats=[#k_literal{anno=A,val=Val}|Ps]}=C, B) ->
P = case B of
true -> expand_pat_lit(Val, A);
false -> literal(Val, A)
end,
C#iclause{pats=[P|Ps]};
expand_pat_lit_clause(#iclause{pats=[#k_binary{anno=A,segs=#k_bin_end{}}|Ps]}=C, B) ->
case B of
true ->
C;
false ->
P = #k_literal{anno=A,val = <<>>},
C#iclause{pats=[P|Ps]}
end;
expand_pat_lit_clause(C, _) -> C.
expand_pat_lit([H|T], A) ->
#k_cons{anno=A,hd=literal(H, A),tl=literal(T, A)};
expand_pat_lit(Tuple, A) when is_tuple(Tuple) ->
#k_tuple{anno=A,es=[literal(E, A) || E <- tuple_to_list(Tuple)]};
expand_pat_lit(Lit, A) ->
literal(Lit, A).
literal([], A) ->
#k_nil{anno=A};
literal(Val, A) when is_integer(Val) ->
#k_int{anno=A,val=Val};
literal(Val, A) when is_float(Val) ->
#k_float{anno=A,val=Val};
literal(Val, A) when is_atom(Val) ->
#k_atom{anno=A,val=Val};
literal(Val, A) when is_list(Val); is_tuple(Val) ->
#k_literal{anno=A,val=Val}.
%% select_bin_con([Clause]) -> [{Type,[Clause]}].
%% Extract clauses for the k_bin_seg constructor. As k_bin_seg
%% matching can overlap, the k_bin_seg constructors cannot be
%% reordered, only grouped.
select_bin_con(Cs0) ->
Cs1 = lists:filter(fun (C) ->
Con = clause_con(C),
(Con =:= k_bin_seg) or (Con =:= k_bin_end)
end, Cs0),
select_bin_con_1(Cs1).
select_bin_con_1(Cs) ->
try
%% The usual way to match literals is to first extract the
%% value to a register, and then compare the register to the
%% literal value. Extracting the value is good if we need
%% compare it more than once.
%%
%% But we would like to combine the extracting and the
%% comparing into a single instruction if we know that
%% a binary segment must contain specific integer value
%% or the matching will fail, like in this example:
%%
%% <<42:8,...>> ->
%% <<42:8,...>> ->
%% .
%% .
%% .
%% <<42:8,...>> ->
%% <<>> ->
%%
%% The first segment must either contain the integer 42
%% or the binary must end for the match to succeed.
%%
%% The way we do is to replace the generic #k_bin_seg{}
%% record with a #k_bin_int{} record if all clauses will
%% select the same literal integer (except for one or more
%% clauses that will end the binary).
{BinSegs0,BinEnd} =
partition(fun (C) ->
clause_con(C) =:= k_bin_seg
end, Cs),
BinSegs = select_bin_int(BinSegs0),
case BinEnd of
[] -> BinSegs;
[_|_] -> BinSegs ++ [{k_bin_end,BinEnd}]
end
catch
throw:not_possible ->
select_bin_con_2(Cs)
end.
select_bin_con_2([C1|Cs]) ->
Con = clause_con(C1),
{More,Rest} = splitwith(fun (C) -> clause_con(C) =:= Con end, Cs),
[{Con,[C1|More]}|select_bin_con_2(Rest)];
select_bin_con_2([]) -> [].
%% select_bin_int([Clause]) -> {k_bin_int,[Clause]}
%% If the first pattern in each clause selects the same integer,
%% rewrite all clauses to use #k_bin_int{} (which will later be
%% translated to a bs_match_string/4 instruction).
%%
%% If it is not possible to do this rewrite, a 'not_possible'
%% exception is thrown.
select_bin_int([#iclause{pats=[#k_bin_seg{anno=A,type=integer,
size=#k_int{val=Bits0}=Sz,unit=U,
flags=Fl,seg=#k_literal{val=Val},
next=N}|Ps]}=C|Cs0])
when is_integer(Val) ->
Bits = U * Bits0,
if
Bits > 1024 -> throw(not_possible); %Expands the code too much.
true -> ok
end,
select_assert_match_possible(Bits, Val, Fl),
P = #k_bin_int{anno=A,size=Sz,unit=U,flags=Fl,val=Val,next=N},
case member(native, Fl) of
true -> throw(not_possible);
false -> ok
end,
Cs = select_bin_int_1(Cs0, Bits, Fl, Val),
[{k_bin_int,[C#iclause{pats=[P|Ps]}|Cs]}];
select_bin_int([#iclause{pats=[#k_bin_seg{anno=A,type=utf8,
flags=[unsigned,big]=Fl,
seg=#k_literal{val=Val0},
next=N}|Ps]}=C|Cs0])
when is_integer(Val0) ->
{Val,Bits} = select_utf8(Val0),
P = #k_bin_int{anno=A,size=#k_int{val=Bits},unit=1,
flags=Fl,val=Val,next=N},
Cs = select_bin_int_1(Cs0, Bits, Fl, Val),
[{k_bin_int,[C#iclause{pats=[P|Ps]}|Cs]}];
select_bin_int(_) -> throw(not_possible).
select_bin_int_1([#iclause{pats=[#k_bin_seg{anno=A,type=integer,
size=#k_int{val=Bits0}=Sz,
unit=U,
flags=Fl,seg=#k_literal{val=Val},
next=N}|Ps]}=C|Cs],
Bits, Fl, Val) when is_integer(Val) ->
if
Bits0*U =:= Bits -> ok;
true -> throw(not_possible)
end,
P = #k_bin_int{anno=A,size=Sz,unit=U,flags=Fl,val=Val,next=N},
[C#iclause{pats=[P|Ps]}|select_bin_int_1(Cs, Bits, Fl, Val)];
select_bin_int_1([#iclause{pats=[#k_bin_seg{anno=A,type=utf8,
flags=Fl,
seg=#k_literal{val=Val0},
next=N}|Ps]}=C|Cs],
Bits, Fl, Val) when is_integer(Val0) ->
case select_utf8(Val0) of
{Val,Bits} -> ok;
{_,_} -> throw(not_possible)
end,
P = #k_bin_int{anno=A,size=#k_int{val=Bits},unit=1,
flags=[unsigned,big],val=Val,next=N},
[C#iclause{pats=[P|Ps]}|select_bin_int_1(Cs, Bits, Fl, Val)];
select_bin_int_1([], _, _, _) -> [];
select_bin_int_1(_, _, _, _) -> throw(not_possible).
select_assert_match_possible(Sz, Val, Fs) ->
EmptyBindings = erl_eval:new_bindings(),
MatchFun = match_fun(Val),
EvalFun = fun({integer,_,S}, B) -> {value,S,B} end,
Expr = [{bin_element,0,{integer,0,Val},{integer,0,Sz},[{unit,1}|Fs]}],
{value,Bin,EmptyBindings} = eval_bits:expr_grp(Expr, EmptyBindings, EvalFun),
try
{match,_} = eval_bits:match_bits(Expr, Bin,
EmptyBindings,
EmptyBindings,
MatchFun, EvalFun),
ok % this is just an assertion (i.e., no return value)
catch
throw:nomatch ->
throw(not_possible)
end.
match_fun(Val) ->
fun(match, {{integer,_,_},NewV,Bs}) when NewV =:= Val ->
{match,Bs}
end.
select_utf8(Val0) ->
try
Bin = <<Val0/utf8>>,
Size = bit_size(Bin),
<<Val:Size>> = Bin,
{Val,Size}
catch
error:_ ->
throw(not_possible)
end.
%% select(Con, [Clause]) -> [Clause].
select(T, Cs) -> [ C || C <- Cs, clause_con(C) =:= T ].
%% match_value([Var], Con, [Clause], Default, State) -> {SelectExpr,State}.
%% At this point all the clauses have the same constructor, we must
%% now separate them according to value.
match_value(Us, T, Cs0, Def, St0) ->
Css = group_value(T, Cs0),
%%ok = io:format("match_value ~p ~p~n", [T, Css]),
mapfoldl(fun (Cs, St) -> match_clause(Us, Cs, Def, St) end, St0, Css).
%% group_value([Clause]) -> [[Clause]].
%% Group clauses according to value. Here we know that
%% 1. Some types are singled valued
%% 2. The clauses in bin_segs cannot be reordered only grouped
%% 3. Other types are disjoint and can be reordered
group_value(k_cons, Cs) -> [Cs]; %These are single valued
group_value(k_nil, Cs) -> [Cs];
group_value(k_binary, Cs) -> [Cs];
group_value(k_bin_end, Cs) -> [Cs];
group_value(k_bin_seg, Cs) ->
group_bin_seg(Cs);
group_value(k_bin_int, Cs) ->
[Cs];
group_value(_, Cs) ->
%% group_value(Cs).
Cd = foldl(fun (C, Gcs0) -> dict:append(clause_val(C), C, Gcs0) end,
dict:new(), Cs),
dict:fold(fun (_, Vcs, Css) -> [Vcs|Css] end, [], Cd).
group_bin_seg([C1|Cs]) ->
V1 = clause_val(C1),
{More,Rest} = splitwith(fun (C) -> clause_val(C) == V1 end, Cs),
[[C1|More]|group_bin_seg(Rest)];
group_bin_seg([]) -> [].
%% Profiling shows that this quadratic implementation account for a big amount
%% of the execution time if there are many values.
% group_value([C|Cs]) ->
% V = clause_val(C),
% Same = [ Cv || Cv <- Cs, clause_val(Cv) == V ], %Same value
% Rest = [ Cv || Cv <- Cs, clause_val(Cv) /= V ], % and all the rest
% [[C|Same]|group_value(Rest)];
% group_value([]) -> [].
%% match_clause([Var], [Clause], Default, State) -> {Clause,State}.
%% At this point all the clauses have the same "value". Build one
%% select clause for this value and continue matching. Rename
%% aliases as well.
match_clause([U|Us], [C|_]=Cs0, Def, St0) ->
Anno = get_kanno(C),
{Match0,Vs,St1} = get_match(get_con(Cs0), St0),
Match = sub_size_var(Match0, Cs0),
{Cs1,St2} = new_clauses(Cs0, U, St1),
{B,St3} = match(Vs ++ Us, Cs1, Def, St2),
{#k_val_clause{anno=Anno,val=Match,body=B},St3}.
sub_size_var(#k_bin_seg{size=#k_var{name=Name}=Kvar}=BinSeg, [#iclause{isub=Sub}|_]) ->
BinSeg#k_bin_seg{size=Kvar#k_var{name=get_vsub(Name, Sub)}};
sub_size_var(K, _) -> K.
get_con([C|_]) -> arg_arg(clause_arg(C)). %Get the constructor
get_match(#k_cons{}, St0) ->
{[H,T]=L,St1} = new_vars(2, St0),
{#k_cons{hd=H,tl=T},L,St1};
get_match(#k_binary{}, St0) ->
{[V]=Mes,St1} = new_vars(1, St0),
{#k_binary{segs=V},Mes,St1};
get_match(#k_bin_seg{size=#k_atom{val=all},next={k_bin_end,[]}}=Seg, St0) ->
{[S]=Vars,St1} = new_vars(1, St0),
{Seg#k_bin_seg{seg=S,next=[]},Vars,St1};
get_match(#k_bin_seg{}=Seg, St0) ->
{[S,N0],St1} = new_vars(2, St0),
N = set_kanno(N0, [no_usage]),
{Seg#k_bin_seg{seg=S,next=N},[S,N],St1};
get_match(#k_bin_int{}=BinInt, St0) ->
{N0,St1} = new_var(St0),
N = set_kanno(N0, [no_usage]),
{BinInt#k_bin_int{next=N},[N],St1};
get_match(#k_tuple{es=Es}, St0) ->
{Mes,St1} = new_vars(length(Es), St0),
{#k_tuple{es=Mes},Mes,St1};
get_match(M, St) ->
{M,[],St}.
new_clauses(Cs0, U, St) ->
Cs1 = map(fun (#iclause{isub=Isub0,osub=Osub0,pats=[Arg|As]}=C) ->
Head = case arg_arg(Arg) of
#k_cons{hd=H,tl=T} -> [H,T|As];
#k_tuple{es=Es} -> Es ++ As;
#k_binary{segs=E} -> [E|As];
#k_bin_seg{size=#k_atom{val=all},
seg=S,next={k_bin_end,[]}} ->
[S|As];
#k_bin_seg{seg=S,next=N} ->
[S,N|As];
#k_bin_int{next=N} ->
[N|As];
_Other -> As
end,
Vs = arg_alias(Arg),
Osub1 = foldl(fun (#k_var{name=V}, Acc) ->
subst_vsub(V, U#k_var.name, Acc)
end, Osub0, Vs),
Isub1 = foldl(fun (#k_var{name=V}, Acc) ->
subst_vsub(V, U#k_var.name, Acc)
end, Isub0, Vs),
C#iclause{isub=Isub1,osub=Osub1,pats=Head}
end, Cs0),
{Cs1,St}.
%% build_guard([GuardClause]) -> GuardExpr.
build_guard([]) -> fail;
build_guard(Cs) -> #k_guard{clauses=Cs}.
%% build_select(Var, [ConClause]) -> SelectExpr.
build_select(V, [Tc|_]=Tcs) ->
copy_anno(#k_select{var=V,types=Tcs}, Tc).
%% build_alt(First, Then) -> AltExpr.
%% Build an alt, attempt some simple optimisation.
build_alt(fail, Then) -> Then;
build_alt(First,Then) -> build_alt_1st_no_fail(First, Then).
build_alt_1st_no_fail(First, fail) -> First;
build_alt_1st_no_fail(First, Then) ->
copy_anno(#k_alt{first=First,then=Then}, First).
%% build_match([MatchVar], MatchExpr) -> Kexpr.
%% Build a match expr if there is a match.
build_match(Us, #k_alt{}=Km) -> copy_anno(#k_match{vars=Us,body=Km}, Km);
build_match(Us, #k_select{}=Km) -> copy_anno(#k_match{vars=Us,body=Km}, Km);
build_match(Us, #k_guard{}=Km) -> copy_anno(#k_match{vars=Us,body=Km}, Km);
build_match(_, Km) -> Km.
%% clause_arg(Clause) -> FirstArg.
%% clause_con(Clause) -> Constructor.
%% clause_val(Clause) -> Value.
%% is_var_clause(Clause) -> boolean().
clause_arg(#iclause{pats=[Arg|_]}) -> Arg.
clause_con(C) -> arg_con(clause_arg(C)).
clause_val(C) -> arg_val(clause_arg(C), C).
is_var_clause(C) -> clause_con(C) =:= k_var.
%% arg_arg(Arg) -> Arg.
%% arg_alias(Arg) -> Aliases.
%% arg_con(Arg) -> Constructor.
%% arg_val(Arg) -> Value.
%% These are the basic functions for obtaining fields in an argument.
arg_arg(#ialias{pat=Con}) -> Con;
arg_arg(Con) -> Con.
arg_alias(#ialias{vars=As}) -> As;
arg_alias(_Con) -> [].
arg_con(Arg) ->
case arg_arg(Arg) of
#k_literal{} -> k_literal;
#k_int{} -> k_int;
#k_float{} -> k_float;
#k_atom{} -> k_atom;
#k_nil{} -> k_nil;
#k_cons{} -> k_cons;
#k_tuple{} -> k_tuple;
#k_binary{} -> k_binary;
#k_bin_end{} -> k_bin_end;
#k_bin_seg{} -> k_bin_seg;
#k_var{} -> k_var
end.
arg_val(Arg, C) ->
case arg_arg(Arg) of
#k_literal{val=Lit} -> Lit;
#k_int{val=I} -> I;
#k_float{val=F} -> F;
#k_atom{val=A} -> A;
#k_tuple{es=Es} -> length(Es);
#k_bin_seg{size=S,unit=U,type=T,flags=Fs} ->
case S of
#k_var{name=V} ->
#iclause{isub=Isub} = C,
{#k_var{name=get_vsub(V, Isub)},U,T,Fs};
_ ->
{set_kanno(S, []),U,T,Fs}
end
end.
%% ubody_used_vars(Expr, State) -> [UsedVar]
%% Return all used variables for the body sequence. Much more
%% efficient than using ubody/3 if the body contains nested letrecs.
ubody_used_vars(Expr, St) ->
{_,Used,_} = ubody(Expr, return, St#kern{funs=ignore}),
Used.
%% ubody(Expr, Break, State) -> {Expr,[UsedVar],State}.
%% Tag the body sequence with its used variables. These bodies
%% either end with a #k_break{}, or with #k_return{} or an expression
%% which itself can return, #k_enter{}, #k_match{} ... .
ubody(#iset{vars=[],arg=#iletrec{}=Let,body=B0}, Br, St0) ->
%% An iletrec{} should never be last.
St = iletrec_funs(Let, St0),
ubody(B0, Br, St);
ubody(#iset{anno=A,vars=Vs,arg=E0,body=B0}, Br, St0) ->
{E1,Eu,St1} = uexpr(E0, {break,Vs}, St0),
{B1,Bu,St2} = ubody(B0, Br, St1),
Ns = lit_list_vars(Vs),
Used = union(Eu, subtract(Bu, Ns)), %Used external vars
{#k_seq{anno=#k{us=Used,ns=Ns,a=A},arg=E1,body=B1},Used,St2};
ubody(#ivalues{anno=A,args=As}, return, St) ->
Au = lit_list_vars(As),
{#k_return{anno=#k{us=Au,ns=[],a=A},args=As},Au,St};
ubody(#ivalues{anno=A,args=As}, {break,_Vbs}, St) ->
Au = lit_list_vars(As),
case is_in_guard(St) of
true ->
{#k_guard_break{anno=#k{us=Au,ns=[],a=A},args=As},Au,St};
false ->
{#k_break{anno=#k{us=Au,ns=[],a=A},args=As},Au,St}
end;
ubody(E, return, St0) ->
%% Enterable expressions need no trailing return.
case is_enter_expr(E) of
true -> uexpr(E, return, St0);
false ->
{Ea,Pa,St1} = force_atomic(E, St0),
ubody(pre_seq(Pa, #ivalues{args=[Ea]}), return, St1)
end;
ubody(E, {break,_Rs} = Break, St0) ->
%%ok = io:fwrite("ubody ~w:~p~n", [?LINE,{E,Br}]),
%% Exiting expressions need no trailing break.
case is_exit_expr(E) of
true -> uexpr(E, return, St0);
false ->
{Ea,Pa,St1} = force_atomic(E, St0),
ubody(pre_seq(Pa, #ivalues{args=[Ea]}), Break, St1)
end.
iletrec_funs(#iletrec{defs=Fs}, St0) ->
%% Use union of all free variables.
%% First just work out free variables for all functions.
Free = foldl(fun ({_,#ifun{vars=Vs,body=Fb0}}, Free0) ->
Fbu = ubody_used_vars(Fb0, St0),
Ns = lit_list_vars(Vs),
Free1 = subtract(Fbu, Ns),
union(Free1, Free0)
end, [], Fs),
FreeVs = make_vars(Free),
%% Add this free info to State.
St1 = foldl(fun ({N,#ifun{vars=Vs}}, Lst) ->
store_free(N, length(Vs), FreeVs, Lst)
end, St0, Fs),
iletrec_funs_gen(Fs, FreeVs, St1).
%% Now regenerate local functions to use free variable information.
iletrec_funs_gen(_, _, #kern{funs=ignore}=St) ->
%% Optimization: The ultimate caller is only interested in the used variables,
%% not the updated state. Makes a difference if there are nested letrecs.
St;
iletrec_funs_gen(Fs, FreeVs, St) ->
foldl(fun ({N,#ifun{anno=Fa,vars=Vs,body=Fb0}}, Lst0) ->
Arity0 = length(Vs),
{Fb1,_,Lst1} = ubody(Fb0, return, Lst0#kern{ff={N,Arity0}}),
Arity = Arity0 + length(FreeVs),
Fun = #k_fdef{anno=#k{us=[],ns=[],a=Fa},
func=N,arity=Arity,
vars=Vs ++ FreeVs,body=Fb1},
Lst1#kern{funs=[Fun|Lst1#kern.funs]}
end, St, Fs).
%% is_exit_expr(Kexpr) -> boolean().
%% Test whether Kexpr always exits and never returns.
is_exit_expr(#k_receive_next{}) -> true;
is_exit_expr(_) -> false.
%% is_enter_expr(Kexpr) -> boolean().
%% Test whether Kexpr is "enterable", i.e. can handle return from
%% within itself without extra #k_return{}.
is_enter_expr(#k_try{}) -> true;
is_enter_expr(#k_call{}) -> true;
is_enter_expr(#k_match{}) -> true;
is_enter_expr(#k_receive{}) -> true;
is_enter_expr(#k_receive_next{}) -> true;
is_enter_expr(_) -> false.
%% uexpr(Expr, Break, State) -> {Expr,[UsedVar],State}.
%% Tag an expression with its used variables.
%% Break = return | {break,[RetVar]}.
uexpr(#k_test{anno=A,op=Op,args=As}=Test, {break,Rs}, St) ->
[] = Rs, %Sanity check
Used = union(op_vars(Op), lit_list_vars(As)),
{Test#k_test{anno=#k{us=Used,ns=lit_list_vars(Rs),a=A}},
Used,St};
uexpr(#iset{anno=A,vars=Vs,arg=E0,body=B0}, {break,_}=Br, St0) ->
Ns = lit_list_vars(Vs),
{E1,Eu,St1} = uexpr(E0, {break,Vs}, St0),
{B1,Bu,St2} = uexpr(B0, Br, St1),
Used = union(Eu, subtract(Bu, Ns)),
{#k_seq{anno=#k{us=Used,ns=Ns,a=A},arg=E1,body=B1},Used,St2};
uexpr(#k_call{anno=A,op=#k_local{name=F,arity=Ar}=Op,args=As0}=Call, Br, St) ->
Free = get_free(F, Ar, St),
As1 = As0 ++ Free, %Add free variables LAST!
Used = lit_list_vars(As1),
{case Br of
{break,Rs} ->
Call#k_call{anno=#k{us=Used,ns=lit_list_vars(Rs),a=A},
op=Op#k_local{arity=Ar + length(Free)},
args=As1,ret=Rs};
return ->
#k_enter{anno=#k{us=Used,ns=[],a=A},
op=Op#k_local{arity=Ar + length(Free)},
args=As1}
end,Used,St};
uexpr(#k_call{anno=A,op=Op,args=As}=Call, {break,Rs}, St) ->
Used = union(op_vars(Op), lit_list_vars(As)),
{Call#k_call{anno=#k{us=Used,ns=lit_list_vars(Rs),a=A},ret=Rs},
Used,St};
uexpr(#k_call{anno=A,op=Op,args=As}, return, St) ->
Used = union(op_vars(Op), lit_list_vars(As)),
{#k_enter{anno=#k{us=Used,ns=[],a=A},op=Op,args=As},
Used,St};
uexpr(#k_bif{anno=A,op=Op,args=As}=Bif, {break,Rs}, St0) ->
Used = union(op_vars(Op), lit_list_vars(As)),
{Brs,St1} = bif_returns(Op, Rs, St0),
{Bif#k_bif{anno=#k{us=Used,ns=lit_list_vars(Brs),a=A},ret=Brs},
Used,St1};
uexpr(#k_match{anno=A,vars=Vs0,body=B0}, Br, St0) ->
Vs = handle_reuse_annos(Vs0, St0),
Rs = break_rets(Br),
{B1,Bu,St1} = umatch(B0, Br, St0),
case is_in_guard(St1) of
true ->
{#k_guard_match{anno=#k{us=Bu,ns=lit_list_vars(Rs),a=A},
vars=Vs,body=B1,ret=Rs},Bu,St1};
false ->
{#k_match{anno=#k{us=Bu,ns=lit_list_vars(Rs),a=A},
vars=Vs,body=B1,ret=Rs},Bu,St1}
end;
uexpr(#k_receive{anno=A,var=V,body=B0,timeout=T,action=A0}, Br, St0) ->
Rs = break_rets(Br),
Tu = lit_vars(T), %Timeout is atomic
{B1,Bu,St1} = umatch(B0, Br, St0),
{A1,Au,St2} = ubody(A0, Br, St1),
Used = del_element(V#k_var.name, union(Bu, union(Tu, Au))),
{#k_receive{anno=#k{us=Used,ns=lit_list_vars(Rs),a=A},
var=V,body=B1,timeout=T,action=A1,ret=Rs},
Used,St2};
uexpr(#k_receive_accept{anno=A}, _, St) ->
{#k_receive_accept{anno=#k{us=[],ns=[],a=A}},[],St};
uexpr(#k_receive_next{anno=A}, _, St) ->
{#k_receive_next{anno=#k{us=[],ns=[],a=A}},[],St};
uexpr(#k_try{anno=A,arg=A0,vars=Vs,body=B0,evars=Evs,handler=H0}=Try,
{break,Rs0}=Br, St0) ->
case is_in_guard(St0) of
true ->
{[#k_var{name=X}],#k_var{name=X}} = {Vs,B0}, %Assertion.
#k_atom{val=false} = H0, %Assertion.
{A1,Bu,St1} = uexpr(A0, Br, St0),
{Try#k_try{anno=#k{us=Bu,ns=lit_list_vars(Rs0),a=A},
arg=A1,ret=Rs0},Bu,St1};
false ->
{Avs,St1} = new_vars(length(Vs), St0),
{A1,Au,St2} = ubody(A0, {break,Avs}, St1),
{B1,Bu,St3} = ubody(B0, Br, St2),
{H1,Hu,St4} = ubody(H0, Br, St3),
{Rs1,St5} = ensure_return_vars(Rs0, St4),
Used = union([Au,subtract(Bu, lit_list_vars(Vs)),
subtract(Hu, lit_list_vars(Evs))]),
{#k_try{anno=#k{us=Used,ns=lit_list_vars(Rs1),a=A},
arg=A1,vars=Vs,body=B1,evars=Evs,handler=H1,ret=Rs1},
Used,St5}
end;
uexpr(#k_try{anno=A,arg=A0,vars=Vs,body=B0,evars=Evs,handler=H0},
return, St0) ->
{Avs,St1} = new_vars(length(Vs), St0), %Need dummy names here
{A1,Au,St2} = ubody(A0, {break,Avs}, St1), %Must break to clean up here!
{B1,Bu,St3} = ubody(B0, return, St2),
{H1,Hu,St4} = ubody(H0, return, St3),
NumNew = 1,
{Ns,St5} = new_vars(NumNew, St4),
Used = union([Au,subtract(Bu, lit_list_vars(Vs)),
subtract(Hu, lit_list_vars(Evs))]),
{#k_try_enter{anno=#k{us=Used,ns=Ns,a=A},
arg=A1,vars=Vs,body=B1,evars=Evs,handler=H1},
Used,St5};
uexpr(#k_catch{anno=A,body=B0}, {break,Rs0}, St0) ->
{Rb,St1} = new_var(St0),
{B1,Bu,St2} = ubody(B0, {break,[Rb]}, St1),
%% Guarantee ONE return variable.
{Ns,St3} = new_vars(1 - length(Rs0), St2),
Rs1 = Rs0 ++ Ns,
{#k_catch{anno=#k{us=Bu,ns=lit_list_vars(Rs1),a=A},body=B1,ret=Rs1},Bu,St3};
uexpr(#ifun{anno=A,vars=Vs,body=B0}, {break,Rs}, St0) ->
{B1,Bu,St1} = ubody(B0, return, St0), %Return out of new function
Ns = lit_list_vars(Vs),
Free = subtract(Bu, Ns), %Free variables in fun
Fvs = make_vars(Free),
Arity = length(Vs) + length(Free),
{Fname,St} =
case lists:keyfind(id, 1, A) of
{id,{_,_,Fname0}} ->
{Fname0,St1};
false ->
%% No id annotation. Must invent a fun name.
new_fun_name(St1)
end,
Fun = #k_fdef{anno=#k{us=[],ns=[],a=A},func=Fname,arity=Arity,
vars=Vs ++ Fvs,body=B1},
%% Set dummy values for Index and Uniq -- the real values will
%% be assigned by beam_asm.
Index = Uniq = 0,
{#k_bif{anno=#k{us=Free,ns=lit_list_vars(Rs),a=A},
op=#k_internal{name=make_fun,arity=length(Free)+3},
args=[#k_atom{val=Fname},#k_int{val=Arity},
#k_int{val=Index},#k_int{val=Uniq}|Fvs],
ret=Rs},
Free,add_local_function(Fun, St)};
uexpr(Lit, {break,Rs0}, St0) ->
%% Transform literals to puts here.
%%ok = io:fwrite("uexpr ~w:~p~n", [?LINE,Lit]),
Used = lit_vars(Lit),
{Rs,St1} = ensure_return_vars(Rs0, St0),
{#k_put{anno=#k{us=Used,ns=lit_list_vars(Rs),a=get_kanno(Lit)},
arg=Lit,ret=Rs},Used,St1}.
add_local_function(_, #kern{funs=ignore}=St) -> St;
add_local_function(F, #kern{funs=Funs}=St) -> St#kern{funs=[F|Funs]}.
%% handle_reuse_annos([#k_var{}], State) -> State.
%% In general, it is only safe to reuse a variable for a match context
%% if the original value of the variable will no longer be needed.
%%
%% If a variable has been bound in an outer letrec and is therefore
%% free in the current function, the variable may still be used.
%% We don't bother to check whether the variable is actually used,
%% but simply clears the 'reuse_for_context' annotation for any variable
%% that is free.
handle_reuse_annos(Vs, St) ->
[handle_reuse_anno(V, St) || V <- Vs].
handle_reuse_anno(#k_var{anno=A}=V, St) ->
case member(reuse_for_context, A) of
false -> V;
true -> handle_reuse_anno_1(V, St)
end.
handle_reuse_anno_1(#k_var{anno=Anno,name=Vname}=V, #kern{ff={F,A}}=St) ->
FreeVs = get_free(F, A, St),
case keymember(Vname, #k_var.name, FreeVs) of
true -> V#k_var{anno=Anno--[reuse_for_context]};
false -> V
end;
handle_reuse_anno_1(V, _St) -> V.
%% get_free(Name, Arity, State) -> [Free].
%% store_free(Name, Arity, [Free], State) -> State.
get_free(F, A, St) ->
case orddict:find({F,A}, St#kern.free) of
{ok,Val} -> Val;
error -> []
end.
store_free(F, A, Free, St) ->
St#kern{free=orddict:store({F,A}, Free, St#kern.free)}.
break_rets({break,Rs}) -> Rs;
break_rets(return) -> [].
%% bif_returns(Op, [Ret], State) -> {[Ret],State}.
bif_returns(#k_remote{mod=M,name=N,arity=Ar}, Rs, St0) ->
%%ok = io:fwrite("uexpr ~w:~p~n", [?LINE,{M,N,Ar,Rs}]),
{Ns,St1} = new_vars(bif_vals(M, N, Ar) - length(Rs), St0),
{Rs ++ Ns,St1};
bif_returns(#k_internal{name=N,arity=Ar}, Rs, St0) ->
%%ok = io:fwrite("uexpr ~w:~p~n", [?LINE,{N,Ar,Rs}]),
{Ns,St1} = new_vars(bif_vals(N, Ar) - length(Rs), St0),
{Rs ++ Ns,St1}.
%% ensure_return_vars([Ret], State) -> {[Ret],State}.
ensure_return_vars([], St) -> new_vars(1, St);
ensure_return_vars([_]=Rs, St) -> {Rs,St}.
%% umatch(Match, Break, State) -> {Match,[UsedVar],State}.
%% Tag a match expression with its used variables.
umatch(#k_alt{anno=A,first=F0,then=T0}, Br, St0) ->
{F1,Fu,St1} = umatch(F0, Br, St0),
{T1,Tu,St2} = umatch(T0, Br, St1),
Used = union(Fu, Tu),
{#k_alt{anno=#k{us=Used,ns=[],a=A},first=F1,then=T1},
Used,St2};
umatch(#k_select{anno=A,var=V0,types=Ts0}, Br, St0) ->
V = handle_reuse_anno(V0, St0),
{Ts1,Tus,St1} = umatch_list(Ts0, Br, St0),
Used = case member(no_usage, get_kanno(V)) of
true -> Tus;
false -> add_element(V#k_var.name, Tus)
end,
{#k_select{anno=#k{us=Used,ns=[],a=A},var=V,types=Ts1},Used,St1};
umatch(#k_type_clause{anno=A,type=T,values=Vs0}, Br, St0) ->
{Vs1,Vus,St1} = umatch_list(Vs0, Br, St0),
{#k_type_clause{anno=#k{us=Vus,ns=[],a=A},type=T,values=Vs1},Vus,St1};
umatch(#k_val_clause{anno=A,val=P0,body=B0}, Br, St0) ->
{U0,Ps} = pat_vars(P0),
P = set_kanno(P0, #k{us=U0,ns=Ps,a=get_kanno(P0)}),
{B1,Bu,St1} = umatch(B0, Br, St0),
Used = union(U0, subtract(Bu, Ps)),
{#k_val_clause{anno=#k{us=Used,ns=[],a=A},val=P,body=B1},
Used,St1};
umatch(#k_guard{anno=A,clauses=Gs0}, Br, St0) ->
{Gs1,Gus,St1} = umatch_list(Gs0, Br, St0),
{#k_guard{anno=#k{us=Gus,ns=[],a=A},clauses=Gs1},Gus,St1};
umatch(#k_guard_clause{anno=A,guard=G0,body=B0}, Br, St0) ->
%%ok = io:fwrite("~w: ~p~n", [?LINE,G0]),
{G1,Gu,St1} = uexpr(G0, {break,[]},
St0#kern{guard_refc=St0#kern.guard_refc+1}),
%%ok = io:fwrite("~w: ~p~n", [?LINE,G1]),
{B1,Bu,St2} = umatch(B0, Br, St1#kern{guard_refc=St1#kern.guard_refc-1}),
Used = union(Gu, Bu),
{#k_guard_clause{anno=#k{us=Used,ns=[],a=A},guard=G1,body=B1},Used,St2};
umatch(B0, Br, St0) -> ubody(B0, Br, St0).
umatch_list(Ms0, Br, St) ->
foldr(fun (M0, {Ms1,Us,Sta}) ->
{M1,Mu,Stb} = umatch(M0, Br, Sta),
{[M1|Ms1],union(Mu, Us),Stb}
end, {[],[],St}, Ms0).
%% op_vars(Op) -> [VarName].
op_vars(#k_remote{mod=Mod,name=Name}) ->
ordsets:from_list([V || #k_var{name=V} <- [Mod,Name]]);
op_vars(#k_internal{}) -> [];
op_vars(Atomic) -> lit_vars(Atomic).
%% lit_vars(Literal) -> [VarName].
%% Return the variables in a literal.
lit_vars(#k_var{name=N}) -> [N];
lit_vars(#k_int{}) -> [];
lit_vars(#k_float{}) -> [];
lit_vars(#k_atom{}) -> [];
%%lit_vars(#k_char{}) -> [];
lit_vars(#k_nil{}) -> [];
lit_vars(#k_cons{hd=H,tl=T}) ->
union(lit_vars(H), lit_vars(T));
lit_vars(#k_binary{segs=V}) -> lit_vars(V);
lit_vars(#k_bin_end{}) -> [];
lit_vars(#k_bin_seg{size=Size,seg=S,next=N}) ->
union(lit_vars(Size), union(lit_vars(S), lit_vars(N)));
lit_vars(#k_tuple{es=Es}) ->
lit_list_vars(Es);
lit_vars(#k_literal{}) -> [].
lit_list_vars(Ps) ->
foldl(fun (P, Vs) -> union(lit_vars(P), Vs) end, [], Ps).
%% pat_vars(Pattern) -> {[UsedVarName],[NewVarName]}.
%% Return variables in a pattern. All variables are new variables
%% except those in the size field of binary segments.
pat_vars(#k_var{name=N}) -> {[],[N]};
%%pat_vars(#k_char{}) -> {[],[]};
pat_vars(#k_literal{}) -> {[],[]};
pat_vars(#k_int{}) -> {[],[]};
pat_vars(#k_float{}) -> {[],[]};
pat_vars(#k_atom{}) -> {[],[]};
pat_vars(#k_nil{}) -> {[],[]};
pat_vars(#k_cons{hd=H,tl=T}) ->
pat_list_vars([H,T]);
pat_vars(#k_binary{segs=V}) ->
pat_vars(V);
pat_vars(#k_bin_seg{size=Size,seg=S}) ->
{U1,New} = pat_list_vars([S]),
{[],U2} = pat_vars(Size),
{union(U1, U2),New};
pat_vars(#k_bin_int{size=Size}) ->
{[],U} = pat_vars(Size),
{U,[]};
pat_vars(#k_bin_end{}) -> {[],[]};
pat_vars(#k_tuple{es=Es}) ->
pat_list_vars(Es).
pat_list_vars(Ps) ->
foldl(fun (P, {Used0,New0}) ->
{Used,New} = pat_vars(P),
{union(Used0, Used),union(New0, New)} end,
{[],[]}, Ps).
make_list(Es) ->
foldr(fun(E, Acc) ->
#c_cons{hd=E,tl=Acc}
end, #c_literal{val=[]}, Es).
%% List of integers in interval [N,M]. Empty list if N > M.
integers(N, M) when N =< M ->
[N|integers(N + 1, M)];
integers(_, _) -> [].
%% is_in_guard(State) -> true|false.
is_in_guard(#kern{guard_refc=Refc}) ->
Refc > 0.
%%%
%%% Handling of errors and warnings.
%%%
-type error() :: 'bad_call' | 'nomatch_shadow' | {'nomatch_shadow', integer()}.
-spec format_error(error()) -> string().
format_error({nomatch_shadow,Line}) ->
M = io_lib:format("this clause cannot match because a previous clause at line ~p "
"always matches", [Line]),
lists:flatten(M);
format_error(nomatch_shadow) ->
"this clause cannot match because a previous clause always matches";
format_error(bad_call) ->
"invalid module and/or function name; this call will always fail";
format_error(bad_segment_size) ->
"binary construction will fail because of a type mismatch".
add_warning(none, Term, Anno, #kern{ws=Ws}=St) ->
File = get_file(Anno),
St#kern{ws=[{File,[{?MODULE,Term}]}|Ws]};
add_warning(Line, Term, Anno, #kern{ws=Ws}=St) ->
File = get_file(Anno),
St#kern{ws=[{File,[{Line,?MODULE,Term}]}|Ws]}.
is_compiler_generated(Ke) ->
Anno = get_kanno(Ke),
member(compiler_generated, Anno).
