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Diffstat (limited to 'lib/dialyzer/test/options1_tests_SUITE_data/src/compiler/v3_life.erl')
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diff --git a/lib/dialyzer/test/options1_tests_SUITE_data/src/compiler/v3_life.erl b/lib/dialyzer/test/options1_tests_SUITE_data/src/compiler/v3_life.erl new file mode 100644 index 0000000000..ff210d83f5 --- /dev/null +++ b/lib/dialyzer/test/options1_tests_SUITE_data/src/compiler/v3_life.erl @@ -0,0 +1,448 @@ +%% ``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 via the world wide web 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. +%% +%% The Initial Developer of the Original Code is Ericsson Utvecklings AB. +%% Portions created by Ericsson are Copyright 1999, Ericsson Utvecklings +%% AB. All Rights Reserved.'' +%% +%% $Id: v3_life.erl,v 1.2 2010/03/04 13:54:20 maria Exp $ +%% +%% Purpose : Convert annotated kernel expressions to annotated beam format. + +%% This module creates beam format annotated with variable lifetime +%% information. Each thing is given an index and for each variable we +%% store the first and last index for its occurrence. The variable +%% database, VDB, attached to each thing is only relevant internally +%% for that thing. +%% +%% For nested things like matches the numbering continues locally and +%% the VDB for that thing refers to the variable usage within that +%% thing. Variables which live through a such a thing are internally +%% given a very large last index. Internally the indexes continue +%% after the index of that thing. This creates no problems as the +%% internal variable info never escapes and externally we only see +%% variable which are alive both before or after. +%% +%% This means that variables never "escape" from a thing and the only +%% way to get values from a thing is to "return" them, with 'break' or +%% 'return'. Externally these values become the return values of the +%% thing. This is no real limitation as most nested things have +%% multiple threads so working out a common best variable usage is +%% difficult. + +-module(v3_life). + +-export([module/2]). + +-export([vdb_find/2]). + +-import(lists, [map/2,foldl/3]). +-import(ordsets, [add_element/2,intersection/2,union/2,union/1]). + +-include("v3_kernel.hrl"). +-include("v3_life.hrl"). + +%% These are not defined in v3_kernel.hrl. +get_kanno(Kthing) -> element(2, Kthing). +%%set_kanno(Kthing, Anno) -> setelement(2, Kthing, Anno). + +module(#k_mdef{name=M,exports=Es,attributes=As,body=Fs0}, Opts) -> + put(?MODULE, Opts), + Fs1 = map(fun function/1, Fs0), + erase(?MODULE), + {ok,{M,Es,As,Fs1}}. + +%% function(Kfunc) -> Func. + +function(#k_fdef{func=F,arity=Ar,vars=Vs,body=Kb}) -> + %%ok = io:fwrite("life ~w: ~p~n", [?LINE,{F,Ar}]), + As = var_list(Vs), + Vdb0 = foldl(fun ({var,N}, Vdb) -> new_var(N, 0, Vdb) end, [], As), + %% Force a top-level match! + B0 = case Kb of + #k_match{} -> Kb; + _ -> + Ka = get_kanno(Kb), + #k_match{anno=#k{us=Ka#k.us,ns=[],a=Ka#k.a}, + vars=Vs,body=Kb,ret=[]} + end, + {B1,_,Vdb1} = body(B0, 1, Vdb0), + {function,F,Ar,As,B1,Vdb1}. + +%% body(Kbody, I, Vdb) -> {[Expr],MaxI,Vdb}. +%% Handle a body, need special cases for transforming match_fails. +%% We KNOW that they only occur last in a body. + +body(#k_seq{arg=#k_put{anno=Pa,arg=Arg,ret=[R]}, + body=#k_enter{anno=Ea,op=#k_internal{name=match_fail,arity=1}, + args=[R]}}, + I, Vdb0) -> + Vdb1 = use_vars(Pa#k.us, I, Vdb0), %All used here + {[match_fail(Arg, I, Pa#k.a ++ Ea#k.a)],I,Vdb1}; +body(#k_enter{anno=Ea,op=#k_internal{name=match_fail,arity=1},args=[Arg]}, + I, Vdb0) -> + Vdb1 = use_vars(Ea#k.us, I, Vdb0), + {[match_fail(Arg, I, Ea#k.a)],I,Vdb1}; +body(#k_seq{arg=Ke,body=Kb}, I, Vdb0) -> + %%ok = io:fwrite("life ~w:~p~n", [?LINE,{Ke,I,Vdb0}]), + A = get_kanno(Ke), + Vdb1 = use_vars(A#k.us, I, new_vars(A#k.ns, I, Vdb0)), + {Es,MaxI,Vdb2} = body(Kb, I+1, Vdb1), + E = expr(Ke, I, Vdb2), + {[E|Es],MaxI,Vdb2}; +body(Ke, I, Vdb0) -> + %%ok = io:fwrite("life ~w:~p~n", [?LINE,{Ke,I,Vdb0}]), + A = get_kanno(Ke), + Vdb1 = use_vars(A#k.us, I, new_vars(A#k.ns, I, Vdb0)), + E = expr(Ke, I, Vdb1), + {[E],I,Vdb1}. + +%% guard(Kguard, I, Vdb) -> Guard. + +guard(#k_try{anno=A,arg=Ts,vars=[#k_var{name=X}],body=#k_var{name=X}, + handler=#k_atom{val=false},ret=Rs}, I, Vdb) -> + %% Lock variables that are alive before try and used afterwards. + %% Don't lock variables that are only used inside the try expression. + Pdb0 = vdb_sub(I, I+1, Vdb), + {T,MaxI,Pdb1} = guard_body(Ts, I+1, Pdb0), + Pdb2 = use_vars(A#k.ns, MaxI+1, Pdb1), %Save "return" values + #l{ke={protected,T,var_list(Rs)},i=I,a=A#k.a,vdb=Pdb2}; +guard(#k_seq{}=G, I, Vdb0) -> + {Es,_,Vdb1} = guard_body(G, I, Vdb0), + #l{ke={block,Es},i=I,vdb=Vdb1,a=[]}; +guard(G, I, Vdb) -> guard_expr(G, I, Vdb). + +%% guard_body(Kbody, I, Vdb) -> {[Expr],MaxI,Vdb}. + +guard_body(#k_seq{arg=Ke,body=Kb}, I, Vdb0) -> + A = get_kanno(Ke), + Vdb1 = use_vars(A#k.us, I, new_vars(A#k.ns, I, Vdb0)), + {Es,MaxI,Vdb2} = guard_body(Kb, I+1, Vdb1), + E = guard_expr(Ke, I, Vdb2), + {[E|Es],MaxI,Vdb2}; +guard_body(Ke, I, Vdb0) -> + A = get_kanno(Ke), + Vdb1 = use_vars(A#k.us, I, new_vars(A#k.ns, I, Vdb0)), + E = guard_expr(Ke, I, Vdb1), + {[E],I,Vdb1}. + +%% guard_expr(Call, I, Vdb) -> Expr + +guard_expr(#k_test{anno=A,op=Op,args=As}, I, _Vdb) -> + #l{ke={test,test_op(Op),atomic_list(As)},i=I,a=A#k.a}; +guard_expr(#k_bif{anno=A,op=Op,args=As,ret=Rs}, I, _Vdb) -> + #l{ke={bif,bif_op(Op),atomic_list(As),var_list(Rs)},i=I,a=A#k.a}; +guard_expr(#k_put{anno=A,arg=Arg,ret=Rs}, I, _Vdb) -> + #l{ke={set,var_list(Rs),literal(Arg)},i=I,a=A#k.a}; +guard_expr(#k_match{anno=A,body=Kb,ret=Rs}, I, Vdb) -> + %% Experimental support for andalso/orelse in guards. + %% Work out imported variables which need to be locked. + Mdb = vdb_sub(I, I+1, Vdb), + M = match(Kb, A#k.us, I+1, Mdb), + #l{ke={match,M,var_list(Rs)},i=I,vdb=use_vars(A#k.us, I+1, Mdb),a=A#k.a}; +guard_expr(G, I, Vdb) -> guard(G, I, Vdb). + +%% expr(Kexpr, I, Vdb) -> Expr. + +expr(#k_call{anno=A,op=Op,args=As,ret=Rs}, I, _Vdb) -> + #l{ke={call,call_op(Op),atomic_list(As),var_list(Rs)},i=I,a=A#k.a}; +expr(#k_enter{anno=A,op=Op,args=As}, I, _Vdb) -> + #l{ke={enter,call_op(Op),atomic_list(As)},i=I,a=A#k.a}; +expr(#k_bif{anno=A,op=Op,args=As,ret=Rs}, I, _Vdb) -> + Bif = k_bif(A, Op, As, Rs), + #l{ke=Bif,i=I,a=A#k.a}; +expr(#k_match{anno=A,body=Kb,ret=Rs}, I, Vdb) -> + %% Work out imported variables which need to be locked. + Mdb = vdb_sub(I, I+1, Vdb), + M = match(Kb, A#k.us, I+1, Mdb), + #l{ke={match,M,var_list(Rs)},i=I,vdb=use_vars(A#k.us, I+1, Mdb),a=A#k.a}; +expr(#k_try{anno=A,arg=Ka,vars=Vs,body=Kb,evars=Evs,handler=Kh,ret=Rs}, I, Vdb) -> + %% Lock variables that are alive before the catch and used afterwards. + %% Don't lock variables that are only used inside the try. + Tdb0 = vdb_sub(I, I+1, Vdb), + %% This is the tricky bit. Lock variables in Arg that are used in + %% the body and handler. Add try tag 'variable'. + Ab = get_kanno(Kb), + Ah = get_kanno(Kh), + Tdb1 = use_vars(Ab#k.us, I+3, use_vars(Ah#k.us, I+3, Tdb0)), + Tdb2 = vdb_sub(I, I+2, Tdb1), + Vnames = fun (Kvar) -> Kvar#k_var.name end, %Get the variable names + {Aes,_,Adb} = body(Ka, I+2, add_var({catch_tag,I+1}, I+1, 1000000, Tdb2)), + {Bes,_,Bdb} = body(Kb, I+4, new_vars(map(Vnames, Vs), I+3, Tdb2)), + {Hes,_,Hdb} = body(Kh, I+4, new_vars(map(Vnames, Evs), I+3, Tdb2)), + #l{ke={'try',#l{ke={block,Aes},i=I+1,vdb=Adb,a=[]}, + var_list(Vs),#l{ke={block,Bes},i=I+3,vdb=Bdb,a=[]}, + var_list(Evs),#l{ke={block,Hes},i=I+3,vdb=Hdb,a=[]}, + var_list(Rs)}, + i=I,vdb=Tdb1,a=A#k.a}; +expr(#k_catch{anno=A,body=Kb,ret=[R]}, I, Vdb) -> + %% Lock variables that are alive before the catch and used afterwards. + %% Don't lock variables that are only used inside the catch. + %% Add catch tag 'variable'. + Cdb0 = vdb_sub(I, I+1, Vdb), + {Es,_,Cdb1} = body(Kb, I+1, add_var({catch_tag,I}, I, 1000000, Cdb0)), + #l{ke={'catch',Es,variable(R)},i=I,vdb=Cdb1,a=A#k.a}; +expr(#k_receive{anno=A,var=V,body=Kb,timeout=T,action=Ka,ret=Rs}, I, Vdb) -> + %% Work out imported variables which need to be locked. + Rdb = vdb_sub(I, I+1, Vdb), + M = match(Kb, add_element(V#k_var.name, A#k.us), I+1, + new_var(V#k_var.name, I, Rdb)), + {Tes,_,Adb} = body(Ka, I+1, Rdb), + #l{ke={receive_loop,atomic_lit(T),variable(V),M, + #l{ke=Tes,i=I+1,vdb=Adb,a=[]},var_list(Rs)}, + i=I,vdb=use_vars(A#k.us, I+1, Vdb),a=A#k.a}; +expr(#k_receive_accept{anno=A}, I, _Vdb) -> + #l{ke=receive_accept,i=I,a=A#k.a}; +expr(#k_receive_next{anno=A}, I, _Vdb) -> + #l{ke=receive_next,i=I,a=A#k.a}; +expr(#k_put{anno=A,arg=Arg,ret=Rs}, I, _Vdb) -> + #l{ke={set,var_list(Rs),literal(Arg)},i=I,a=A#k.a}; +expr(#k_break{anno=A,args=As}, I, _Vdb) -> + #l{ke={break,atomic_list(As)},i=I,a=A#k.a}; +expr(#k_return{anno=A,args=As}, I, _Vdb) -> + #l{ke={return,atomic_list(As)},i=I,a=A#k.a}. + +%% call_op(Op) -> Op. +%% bif_op(Op) -> Op. +%% test_op(Op) -> Op. +%% Do any necessary name translations here to munge into beam format. + +call_op(#k_local{name=N}) -> N; +call_op(#k_remote{mod=M,name=N}) -> {remote,atomic_lit(M),atomic_lit(N)}; +call_op(Other) -> variable(Other). + +bif_op(#k_remote{mod=#k_atom{val=erlang},name=#k_atom{val=N}}) -> N; +bif_op(#k_internal{name=N}) -> N. + +test_op(#k_remote{mod=#k_atom{val=erlang},name=#k_atom{val=N}}) -> N. + +%% k_bif(Anno, Op, [Arg], [Ret]) -> Expr. +%% Build bifs, do special handling of internal some calls. + +k_bif(_A, #k_internal{name=dsetelement,arity=3}, As, []) -> + {bif,dsetelement,atomic_list(As),[]}; +k_bif(_A, #k_internal{name=make_fun}, + [#k_atom{val=Fun},#k_int{val=Arity}, + #k_int{val=Index},#k_int{val=Uniq}|Free], + Rs) -> + {bif,{make_fun,Fun,Arity,Index,Uniq},var_list(Free),var_list(Rs)}; +k_bif(_A, Op, As, Rs) -> + %% The general case. + {bif,bif_op(Op),atomic_list(As),var_list(Rs)}. + +%% match(Kexpr, [LockVar], I, Vdb) -> Expr. +%% Convert match tree to old format. + +match(#k_alt{anno=A,first=Kf,then=Kt}, Ls, I, Vdb0) -> + Vdb1 = use_vars(union(A#k.us, Ls), I, Vdb0), + F = match(Kf, Ls, I+1, Vdb1), + T = match(Kt, Ls, I+1, Vdb1), + #l{ke={alt,F,T},i=I,vdb=Vdb1,a=A#k.a}; +match(#k_select{anno=A,var=V,types=Kts}, Ls0, I, Vdb0) -> + Ls1 = add_element(V#k_var.name, Ls0), + Vdb1 = use_vars(union(A#k.us, Ls1), I, Vdb0), + Ts = map(fun (Tc) -> type_clause(Tc, Ls1, I+1, Vdb1) end, Kts), + #l{ke={select,literal(V),Ts},i=I,vdb=Vdb1,a=A#k.a}; +match(#k_guard{anno=A,clauses=Kcs}, Ls, I, Vdb0) -> + Vdb1 = use_vars(union(A#k.us, Ls), I, Vdb0), + Cs = map(fun (G) -> guard_clause(G, Ls, I+1, Vdb1) end, Kcs), + #l{ke={guard,Cs},i=I,vdb=Vdb1,a=A#k.a}; +match(Other, Ls, I, Vdb0) -> + Vdb1 = use_vars(Ls, I, Vdb0), + {B,_,Vdb2} = body(Other, I+1, Vdb1), + #l{ke={block,B},i=I,vdb=Vdb2,a=[]}. + +type_clause(#k_type_clause{anno=A,type=T,values=Kvs}, Ls, I, Vdb0) -> + %%ok = io:format("life ~w: ~p~n", [?LINE,{T,Kvs}]), + Vdb1 = use_vars(union(A#k.us, Ls), I+1, Vdb0), + Vs = map(fun (Vc) -> val_clause(Vc, Ls, I+1, Vdb1) end, Kvs), + #l{ke={type_clause,type(T),Vs},i=I,vdb=Vdb1,a=A#k.a}. + +val_clause(#k_val_clause{anno=A,val=V,body=Kb}, Ls0, I, Vdb0) -> + {_Used,New} = match_pat_vars(V), + %% Not clear yet how Used should be used. + Bus = (get_kanno(Kb))#k.us, + %%ok = io:format("Ls0 = ~p, Used=~p\n New=~p, Bus=~p\n", [Ls0,Used,New,Bus]), + Ls1 = union(intersection(New, Bus), Ls0), %Lock for safety + Vdb1 = use_vars(union(A#k.us, Ls1), I+1, new_vars(New, I, Vdb0)), + B = match(Kb, Ls1, I+1, Vdb1), + #l{ke={val_clause,literal(V),B},i=I,vdb=use_vars(Bus, I+1, Vdb1),a=A#k.a}. + +guard_clause(#k_guard_clause{anno=A,guard=Kg,body=Kb}, Ls, I, Vdb0) -> + Vdb1 = use_vars(union(A#k.us, Ls), I+2, Vdb0), + Gdb = vdb_sub(I+1, I+2, Vdb1), + G = guard(Kg, I+1, Gdb), + B = match(Kb, Ls, I+2, Vdb1), + #l{ke={guard_clause,G,B}, + i=I,vdb=use_vars((get_kanno(Kg))#k.us, I+2, Vdb1), + a=A#k.a}. + +%% match_fail(FailValue, I, Anno) -> Expr. +%% Generate the correct match_fail instruction. N.B. there is no +%% generic case for when the fail value has been created elsewhere. + +match_fail(#k_tuple{es=[#k_atom{val=function_clause}|As]}, I, A) -> + #l{ke={match_fail,{function_clause,literal_list(As)}},i=I,a=A}; +match_fail(#k_tuple{es=[#k_atom{val=badmatch},Val]}, I, A) -> + #l{ke={match_fail,{badmatch,literal(Val)}},i=I,a=A}; +match_fail(#k_tuple{es=[#k_atom{val=case_clause},Val]}, I, A) -> + #l{ke={match_fail,{case_clause,literal(Val)}},i=I,a=A}; +match_fail(#k_atom{val=if_clause}, I, A) -> + #l{ke={match_fail,if_clause},i=I,a=A}; +match_fail(#k_tuple{es=[#k_atom{val=try_clause},Val]}, I, A) -> + #l{ke={match_fail,{try_clause,literal(Val)}},i=I,a=A}. + +%% type(Ktype) -> Type. + +type(k_int) -> integer; +type(k_char) -> integer; %Hhhmmm??? +type(k_float) -> float; +type(k_atom) -> atom; +type(k_nil) -> nil; +type(k_cons) -> cons; +type(k_tuple) -> tuple; +type(k_binary) -> binary; +type(k_bin_seg) -> bin_seg; +type(k_bin_end) -> bin_end. + +%% variable(Klit) -> Lit. +%% var_list([Klit]) -> [Lit]. + +variable(#k_var{name=N}) -> {var,N}. + +var_list(Ks) -> map(fun variable/1, Ks). + +%% atomic_lit(Klit) -> Lit. +%% atomic_list([Klit]) -> [Lit]. + +atomic_lit(#k_var{name=N}) -> {var,N}; +atomic_lit(#k_int{val=I}) -> {integer,I}; +atomic_lit(#k_float{val=F}) -> {float,F}; +atomic_lit(#k_atom{val=N}) -> {atom,N}; +%%atomic_lit(#k_char{val=C}) -> {char,C}; +%%atomic_lit(#k_string{val=S}) -> {string,S}; +atomic_lit(#k_nil{}) -> nil. + +atomic_list(Ks) -> map(fun atomic_lit/1, Ks). + +%% literal(Klit) -> Lit. +%% literal_list([Klit]) -> [Lit]. + +literal(#k_var{name=N}) -> {var,N}; +literal(#k_int{val=I}) -> {integer,I}; +literal(#k_float{val=F}) -> {float,F}; +literal(#k_atom{val=N}) -> {atom,N}; +%%literal(#k_char{val=C}) -> {char,C}; +literal(#k_string{val=S}) -> {string,S}; +literal(#k_nil{}) -> nil; +literal(#k_cons{hd=H,tl=T}) -> + {cons,[literal(H),literal(T)]}; +literal(#k_binary{segs=V}) -> + case proplists:get_bool(no_new_binaries, get(?MODULE)) of + true -> + {old_binary,literal(V)}; + false -> + {binary,literal(V)} + end; +literal(#k_bin_seg{size=S,unit=U,type=T,flags=Fs,seg=Seg,next=N}) -> + {bin_seg,literal(S),U,T,Fs,[literal(Seg),literal(N)]}; +literal(#k_bin_end{}) -> bin_end; +literal(#k_tuple{es=Es}) -> + {tuple,literal_list(Es)}. + +literal_list(Ks) -> map(fun literal/1, Ks). + +%% match_pat_vars(Pattern) -> {[UsedVarName],[NewVarName]}. + +match_pat_vars(#k_var{name=N}) -> {[],[N]}; +match_pat_vars(#k_int{}) -> {[],[]}; +match_pat_vars(#k_float{}) -> {[],[]}; +match_pat_vars(#k_atom{}) -> {[],[]}; +%%match_pat_vars(#k_char{}) -> {[],[]}; +match_pat_vars(#k_string{}) -> {[],[]}; +match_pat_vars(#k_nil{}) -> {[],[]}; +match_pat_vars(#k_cons{hd=H,tl=T}) -> + match_pat_list_vars([H,T]); +match_pat_vars(#k_binary{segs=V}) -> + match_pat_vars(V); +match_pat_vars(#k_bin_seg{size=S,seg=Seg,next=N}) -> + {U1,New1} = match_pat_vars(Seg), + {U2,New2} = match_pat_vars(N), + {[],U3} = match_pat_vars(S), + {union([U1,U2,U3]),union(New1, New2)}; +match_pat_vars(#k_bin_end{}) -> {[],[]}; +match_pat_vars(#k_tuple{es=Es}) -> + match_pat_list_vars(Es). + +match_pat_list_vars(Ps) -> + foldl(fun (P, {Used0,New0}) -> + {Used,New} = match_pat_vars(P), + {union(Used0, Used),union(New0, New)} end, + {[],[]}, Ps). + +%% new_var(VarName, I, Vdb) -> Vdb. +%% new_vars([VarName], I, Vdb) -> Vdb. +%% use_var(VarName, I, Vdb) -> Vdb. +%% use_vars([VarName], I, Vdb) -> Vdb. +%% add_var(VarName, F, L, Vdb) -> Vdb. + +new_var(V, I, Vdb) -> + case vdb_find(V, Vdb) of + {V,F,L} when I < F -> vdb_store(V, I, L, Vdb); + {V,_,_} -> Vdb; + error -> vdb_store(V, I, I, Vdb) + end. + +new_vars(Vs, I, Vdb0) -> + foldl(fun (V, Vdb) -> new_var(V, I, Vdb) end, Vdb0, Vs). + +use_var(V, I, Vdb) -> + case vdb_find(V, Vdb) of + {V,F,L} when I > L -> vdb_store(V, F, I, Vdb); + {V,_,_} -> Vdb; + error -> vdb_store(V, I, I, Vdb) + end. + +use_vars(Vs, I, Vdb0) -> + foldl(fun (V, Vdb) -> use_var(V, I, Vdb) end, Vdb0, Vs). + +add_var(V, F, L, Vdb) -> + use_var(V, L, new_var(V, F, Vdb)). + +vdb_find(V, Vdb) -> + %% Peformance note: Profiling shows that this function accounts for + %% a lot of the execution time when huge constants terms are built. + %% Using the BIF lists:keysearch/3 is a lot faster than the + %% original Erlang version. + case lists:keysearch(V, 1, Vdb) of + {value,Vd} -> Vd; + false -> error + end. + +%vdb_find(V, [{V1,F,L}=Vd|Vdb]) when V < V1 -> error; +%vdb_find(V, [{V1,F,L}=Vd|Vdb]) when V == V1 -> Vd; +%vdb_find(V, [{V1,F,L}=Vd|Vdb]) when V > V1 -> vdb_find(V, Vdb); +%vdb_find(V, []) -> error. + +vdb_store(V, F, L, [{V1,_,_}=Vd|Vdb]) when V > V1 -> + [Vd|vdb_store(V, F, L, Vdb)]; +vdb_store(V, F, L, [{V1,_,_}=Vd|Vdb]) when V < V1 -> [{V,F,L},Vd|Vdb]; +vdb_store(V, F, L, [{_V1,_,_}|Vdb]) -> [{V,F,L}|Vdb]; %V == V1 +vdb_store(V, F, L, []) -> [{V,F,L}]. + +%% vdb_sub(Min, Max, Vdb) -> Vdb. +%% Extract variables which are used before and after Min. Lock +%% variables alive after Max. + +vdb_sub(Min, Max, Vdb) -> + [ if L >= Max -> {V,F,1000000}; + true -> Vd + end || {V,F,L}=Vd <- Vdb, F < Min, L >= Min ]. |