diff options
Diffstat (limited to 'lib/compiler/src/v3_kernel.erl')
| -rw-r--r-- | lib/compiler/src/v3_kernel.erl | 490 |
1 files changed, 478 insertions, 12 deletions
diff --git a/lib/compiler/src/v3_kernel.erl b/lib/compiler/src/v3_kernel.erl index b4bbc5e739..2bfa610628 100644 --- a/lib/compiler/src/v3_kernel.erl +++ b/lib/compiler/src/v3_kernel.erl @@ -82,7 +82,7 @@ -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,droplast/1,last/1]). + keymember/3,keyfind/3,partition/2,droplast/1,last/1,sort/1]). -import(ordsets, [add_element/2,del_element/2,union/2,union/1,subtract/2]). -import(cerl, [c_tuple/1]). @@ -190,9 +190,479 @@ body(Ce, Sub, St0) -> guard(G0, Sub, St0) -> {G1,St1} = wrap_guard(G0, St0), {Ge0,Pre,St2} = expr(G1, Sub, St1), - {Ge,St} = gexpr_test(Ge0, St2), + {Ge1,St3} = gexpr_test(Ge0, St2), + {Ge,St} = guard_opt(Ge1, St3), {pre_seq(Pre, Ge),St}. +%% guard_opt(Kexpr, State) -> {Kexpr,State}. +%% Optimize the Kexpr for the guard. Instead of evaluating a boolean +%% expression comparing it to 'true' in a final #k_test{}, +%% replace BIF calls with #k_test{} in the expression. +%% +%% As an example, take the guard: +%% +%% when is_integer(V0), is_atom(V1) -> +%% +%% The unoptimized Kexpr translated to pseudo BEAM assembly +%% code would look like: +%% +%% bif is_integer V0 => Bool0 +%% bif is_atom V1 => Bool1 +%% bif and Bool0 Bool1 => Bool +%% test Bool =:= true else goto Fail +%% ... +%% Fail: +%% ... +%% +%% The optimized code would look like: +%% +%% test is_integer V0 else goto Fail +%% test is_atom V1 else goto Fail +%% ... +%% Fail: +%% ... +%% +%% An 'or' operation is only slightly more complicated: +%% +%% test is_integer V0 else goto NotFailedYet +%% goto Success +%% +%% NotFailedYet: +%% test is_atom V1 else goto Fail +%% +%% Success: +%% ... +%% Fail: +%% ... + +guard_opt(G, St0) -> + {Root,Forest0,St1} = make_forest(G, St0), + {Exprs,Forest,St} = rewrite_bool(Root, Forest0, false, St1), + E = forest_pre_seq(Exprs, Forest), + {G#k_try{arg=E},St}. + +%% rewrite_bool(Kexpr, Forest, Inv, St) -> {[Kexpr],Forest,St}. +%% Rewrite Kexpr to use #k_test{} operations instead of comparison +%% and type test BIFs. +%% +%% If Kexpr is a #k_test{} operation, the call will always +%% succeed. Otherwise, a 'not_possible' exception will be +%% thrown if Kexpr cannot be rewritten. + +rewrite_bool(#k_test{op=#k_remote{mod=#k_atom{val=erlang},name=#k_atom{val='=:='}}, + args=[#k_var{}=V,#k_atom{val=true}]}=Test, Forest0, Inv, St0) -> + try rewrite_bool_var(V, Forest0, Inv, St0) of + {_,_,_}=Res -> + Res + catch + throw:not_possible -> + {[Test],Forest0,St0} + end; +rewrite_bool(#k_test{op=#k_remote{mod=#k_atom{val=erlang},name=#k_atom{val='=:='}}, + args=[#k_var{}=V,#k_atom{val=false}]}=Test, Forest0, Inv, St0) -> + try rewrite_bool_var(V, Forest0, not Inv, St0) of + {_,_,_}=Res -> + Res + catch + throw:not_possible -> + {[Test],Forest0,St0} + end; +rewrite_bool(#k_test{op=#k_remote{mod=#k_atom{val=erlang},name=#k_atom{val='=:='}}, + args=[#k_atom{val=V1},#k_atom{val=V2}]}, Forest0, false, St0) -> + case V1 =:= V2 of + true -> + {[make_test(is_boolean, [#k_atom{val=true}])],Forest0,St0}; + false -> + {[make_failing_test()],Forest0,St0} + end; +rewrite_bool(#k_test{}=Test, Forest, false, St) -> + {[Test],Forest,St}; +rewrite_bool(#k_try{vars=[#k_var{name=X}],body=#k_var{name=X}, + handler=#k_atom{val=false},ret=[]}=Prot, + Forest0, Inv, St0) -> + {Root,Forest1,St1} = make_forest(Prot, Forest0, St0), + {Exprs,Forest2,St} = rewrite_bool(Root, Forest1, Inv, St1), + InnerForest = maps:without(maps:keys(Forest0), Forest2), + Forest = maps:without(maps:keys(InnerForest), Forest2), + E = forest_pre_seq(Exprs, InnerForest), + {[Prot#k_try{arg=E}],Forest,St}; +rewrite_bool(#k_match{body=Body,ret=[]}, Forest, Inv, St) -> + rewrite_match(Body, Forest, Inv, St); +rewrite_bool(Other, Forest, Inv, St) -> + case extract_bif(Other) of + {Name,Args} -> + rewrite_bif(Name, Args, Forest, Inv, St); + error -> + throw(not_possible) + end. + +%% rewrite_bool_var(Var, Forest, Inv, St) -> {[Kexpr],Forest,St}. +%% Rewrite the boolean expression whose key in Forest is +%% given by Var. Throw a 'not_possible' expression if something +%% prevents the rewriting. + +rewrite_bool_var(Arg, Forest0, Inv, St) -> + {Expr,Forest} = forest_take_expr(Arg, Forest0), + rewrite_bool(Expr, Forest, Inv, St). + +%% rewrite_bool_args([Kexpr], Forest, Inv, St) -> {[[Kexpr]],Forest,St}. +%% Rewrite each Kexpr in the list. The input Kexpr should be variables +%% or boolean values. Throw a 'not_possible' expression if something +%% prevents the rewriting. +%% +%% This function is suitable for handling the arguments for both +%% 'and' and 'or'. + +rewrite_bool_args([#k_atom{val=B}=A|Vs], Forest0, false=Inv, St0) when is_boolean(B) -> + {Tail,Forest1,St1} = rewrite_bool_args(Vs, Forest0, Inv, St0), + Bif = make_bif('=:=', [A,#k_atom{val=true}]), + {Exprs,Forest,St} = rewrite_bool(Bif, Forest1, Inv, St1), + {[Exprs|Tail],Forest,St}; +rewrite_bool_args([#k_var{}=Var|Vs], Forest0, false=Inv, St0) -> + {Tail,Forest1,St1} = rewrite_bool_args(Vs, Forest0, Inv, St0), + {Exprs,Forest,St} = + case is_bool_expr(Var, Forest0) of + true -> + rewrite_bool_var(Var, Forest1, Inv, St1); + false -> + Bif = make_bif('=:=', [Var,#k_atom{val=true}]), + rewrite_bool(Bif, Forest1, Inv, St1) + end, + {[Exprs|Tail],Forest,St}; +rewrite_bool_args([_|_], _Forest, _Inv, _St) -> + throw(not_possible); +rewrite_bool_args([], Forest, _Inv, St) -> + {[],Forest,St}. + +%% rewrite_bif(Name, [Kexpr], Forest, Inv, St) -> {[Kexpr],Forest,St}. +%% Rewrite a BIF. Throw a 'not_possible' expression if something +%% prevents the rewriting. + +rewrite_bif('or', Args, Forest, true, St) -> + rewrite_not_args('and', Args, Forest, St); +rewrite_bif('and', Args, Forest, true, St) -> + rewrite_not_args('or', Args, Forest, St); +rewrite_bif('and', [#k_atom{val=Val},Arg], Forest0, Inv, St0) -> + false = Inv, %Assertion. + case Val of + true -> + %% The result only depends on Arg. + rewrite_bool_var(Arg, Forest0, Inv, St0); + _ -> + %% Will fail. There is no need to evalute the expression + %% represented by Arg. Take it out from the forest and + %% discard the expression. + Failing = make_failing_test(), + try rewrite_bool_var(Arg, Forest0, Inv, St0) of + {_,Forest,St} -> + {[Failing],Forest,St} + catch + throw:not_possible -> + try forest_take_expr(Arg, Forest0) of + {_,Forest} -> + {[Failing],Forest,St0} + catch + throw:not_possible -> + %% Arg is probably a variable bound in an + %% outer scope. + {[Failing],Forest0,St0} + end + end + end; +rewrite_bif('and', [Arg,#k_atom{}=Atom], Forest, Inv, St) -> + false = Inv, %Assertion. + rewrite_bif('and', [Atom,Arg], Forest, Inv, St); +rewrite_bif('and', Args, Forest0, Inv, St0) -> + false = Inv, %Assertion. + {[Es1,Es2],Forest,St} = rewrite_bool_args(Args, Forest0, Inv, St0), + {Es1 ++ Es2,Forest,St}; +rewrite_bif('or', Args, Forest0, Inv, St0) -> + false = Inv, %Assertion. + {[First,Then],Forest,St} = rewrite_bool_args(Args, Forest0, Inv, St0), + Alt = make_alt(First, Then), + {[Alt],Forest,St}; +rewrite_bif('xor', [_,_], _Forest, _Inv, _St) -> + %% Rewriting 'xor' is not practical. Fortunately, 'xor' is + %% almost never used in practice. + throw(not_possible); +rewrite_bif('not', [Arg], Forest0, Inv, St) -> + {Expr,Forest} = forest_take_expr(Arg, Forest0), + rewrite_bool(Expr, Forest, not Inv, St); +rewrite_bif(Op, Args, Forest, Inv, St) -> + case is_test(Op, Args) of + true -> + rewrite_bool(make_test(Op, Args, Inv), Forest, false, St); + false -> + throw(not_possible) + end. + +rewrite_not_args(Op, [A0,B0], Forest0, St0) -> + {A,Forest1,St1} = rewrite_not_args_1(A0, Forest0, St0), + {B,Forest2,St2} = rewrite_not_args_1(B0, Forest1, St1), + rewrite_bif(Op, [A,B], Forest2, false, St2). + +rewrite_not_args_1(Arg, Forest, St) -> + Not = make_bif('not', [Arg]), + forest_add_expr(Not, Forest, St). + +%% rewrite_match(Kvar, TypeClause, Forest, Inv, St) -> +%% {[Kexpr],Forest,St}. +%% Try to rewrite a #k_match{} originating from an 'andalso' or an 'orelse'. + +rewrite_match(#k_alt{first=First,then=Then}, Forest, Inv, St) -> + case {First,Then} of + {#k_select{var=#k_var{name=V}=Var,types=[TypeClause]},#k_var{name=V}} -> + rewrite_match_1(Var, TypeClause, Forest, Inv, St); + {_,_} -> + throw(not_possible) + end. + +rewrite_match_1(Var, #k_type_clause{values=Cs0}, Forest0, Inv, St0) -> + Cs = sort([{Val,B} || #k_val_clause{val=#k_atom{val=Val},body=B} <- Cs0]), + case Cs of + [{false,False},{true,True}] -> + rewrite_match_2(Var, False, True, Forest0, Inv, St0); + _ -> + throw(not_possible) + end. + +rewrite_match_2(Var, False, #k_atom{val=true}, Forest0, Inv, St0) -> + %% Originates from an 'orelse'. + case False of + #k_atom{val=NotBool} when not is_boolean(NotBool) -> + rewrite_bool(Var, Forest0, Inv, St0); + _ -> + {CodeVar,Forest1,St1} = add_protected_expr(False, Forest0, St0), + rewrite_bif('or', [Var,CodeVar], Forest1, Inv, St1) + end; +rewrite_match_2(Var, #k_atom{val=false}, True, Forest0, Inv, St0) -> + %% Originates from an 'andalso'. + {CodeVar,Forest1,St1} = add_protected_expr(True, Forest0, St0), + rewrite_bif('and', [Var,CodeVar], Forest1, Inv, St1); +rewrite_match_2(_V, _, _, _Forest, _Inv, _St) -> + throw(not_possible). + +%% is_bool_expr(#k_var{}, Forest) -> true|false. +%% Return true if the variable refers to a boolean expression +%% that does not need an explicit '=:= true' test. + +is_bool_expr(V, Forest) -> + case forest_peek_expr(V, Forest) of + error -> + %% Defined outside of the guard. We can't know. + false; + Expr -> + case extract_bif(Expr) of + {Name,Args} -> + is_test(Name, Args) orelse + erl_internal:bool_op(Name, length(Args)); + error -> + %% Not a BIF. Should be possible to rewrite + %% to a boolean. Definitely does not need + %% a '=:= true' test. + true + end + end. + +make_bif(Op, Args) -> + #k_bif{op=#k_remote{mod=#k_atom{val=erlang}, + name=#k_atom{val=Op}, + arity=length(Args)}, + args=Args}. + +extract_bif(#k_bif{op=#k_remote{mod=#k_atom{val=erlang}, + name=#k_atom{val=Name}}, + args=Args}) -> + {Name,Args}; +extract_bif(_) -> + error. + +%% make_alt(First, Then) -> KMatch. +%% Make a #k_alt{} within a #k_match{} to implement +%% 'or' or 'orelse'. + +make_alt(First0, Then0) -> + First1 = pre_seq(droplast(First0), last(First0)), + Then1 = pre_seq(droplast(Then0), last(Then0)), + First2 = make_protected(First1), + Then2 = make_protected(Then1), + Body = #k_atom{val=ignored}, + First3 = #k_guard_clause{guard=First2,body=Body}, + Then3 = #k_guard_clause{guard=Then2,body=Body}, + First = #k_guard{clauses=[First3]}, + Then = #k_guard{clauses=[Then3]}, + Alt = #k_alt{first=First,then=Then}, + #k_match{vars=[],body=Alt}. + +add_protected_expr(#k_atom{}=Atom, Forest, St) -> + {Atom,Forest,St}; +add_protected_expr(#k_var{}=Var, Forest, St) -> + {Var,Forest,St}; +add_protected_expr(E0, Forest, St) -> + E = make_protected(E0), + forest_add_expr(E, Forest, St). + +make_protected(#k_try{}=Try) -> + Try; +make_protected(B) -> + #k_try{arg=B,vars=[#k_var{name=''}],body=#k_var{name=''}, + handler=#k_atom{val=false}}. + +make_failing_test() -> + make_test(is_boolean, [#k_atom{val=fail}]). + +make_test(Op, Args) -> + make_test(Op, Args, false). + +make_test(Op, Args, Inv) -> + Remote = #k_remote{mod=#k_atom{val=erlang}, + name=#k_atom{val=Op}, + arity=length(Args)}, + #k_test{op=Remote,args=Args,inverted=Inv}. + +is_test(Op, Args) -> + A = length(Args), + erl_internal:new_type_test(Op, A) orelse erl_internal:comp_op(Op, A). + +%% make_forest(Kexpr, St) -> {RootKexpr,Forest,St}. +%% Build a forest out of Kexpr. RootKexpr is the final expression +%% nested inside Kexpr. + +make_forest(G, St) -> + make_forest_1(G, #{}, 0, St). + +%% make_forest(Kexpr, St) -> {RootKexpr,Forest,St}. +%% Add to Forest from Kexpr. RootKexpr is the final expression +%% nested inside Kexpr. + +make_forest(G, Forest0, St) -> + N = forest_next_index(Forest0), + make_forest_1(G, Forest0, N, St). + +make_forest_1(#k_try{arg=B}, Forest, I, St) -> + make_forest_1(B, Forest, I, St); +make_forest_1(#iset{vars=[]}=Iset0, Forest, I, St0) -> + {UnrefVar,St} = new_var(St0), + Iset = Iset0#iset{vars=[UnrefVar]}, + make_forest_1(Iset, Forest, I, St); +make_forest_1(#iset{vars=[#k_var{name=V}],arg=Arg,body=B}, Forest0, I, St) -> + Forest = Forest0#{V => {I,Arg}, {untaken,V} => true}, + make_forest_1(B, Forest, I+1, St); +make_forest_1(Innermost, Forest, _I, St) -> + {Innermost,Forest,St}. + +%% forest_take_expr(Kexpr, Forest) -> {Expr,Forest}. +%% If Kexpr is a variable, take out the expression corresponding +%% to variable in Forest. Expressions that have been taken out +%% of the forest will not be included the Kexpr returned +%% by forest_pre_seq/2. +%% +%% Throw a 'not_possible' exception if Kexpr is not a variable or +%% if the name of the variable is not a key in Forest. + +forest_take_expr(#k_var{name=V}, Forest0) -> + %% v3_core currently always generates guard expressions that can + %% be represented as a tree. Other code generators (such as LFE) + %% could generate guard expressions that can only be represented + %% as a DAG (i.e. some nodes are referenced more than once). To + %% handle DAGs, we must never remove a node from the forest, but + %% just remove the {untaken,V} marker. That will effectively convert + %% the DAG to a tree by duplicating the shared nodes and their + %% descendants. + + case maps:find(V, Forest0) of + {ok,{_,Expr}} -> + Forest = maps:remove({untaken,V}, Forest0), + {Expr,Forest}; + error -> + throw(not_possible) + end; +forest_take_expr(_, _) -> + throw(not_possible). + +%% forest_peek_expr(Kvar, Forest) -> Kexpr | error. +%% Return the expression corresponding to Kvar in Forest or +%% return 'error' if there is a corresponding expression. + +forest_peek_expr(#k_var{name=V}, Forest0) -> + case maps:find(V, Forest0) of + {ok,{_,Expr}} -> Expr; + error -> error + end. + +%% forest_add_expr(Kexpr, Forest, St) -> {Kvar,Forest,St}. +%% Add a new expression to Forest. + +forest_add_expr(Expr, Forest0, St0) -> + {#k_var{name=V}=Var,St} = new_var(St0), + N = forest_next_index(Forest0), + Forest = Forest0#{V => {N,Expr}}, + {Var,Forest,St}. + +forest_next_index(Forest) -> + 1 + lists:max([N || {N,_} <- maps:values(Forest), + is_integer(N)] ++ [0]). + +%% forest_pre_seq([Kexpr], Forest) -> Kexpr. +%% Package the list of Kexprs into a nested Kexpr, prepending all +%% expressions in Forest that have not been taken out using +%% forest_take_expr/2. + +forest_pre_seq(Exprs, Forest) -> + Es0 = [#k_var{name=V} || {untaken,V} <- maps:keys(Forest)], + Es = Es0 ++ Exprs, + Vs = extract_all_vars(Es, Forest, []), + Pre0 = sort([{maps:get(V, Forest),V} || V <- Vs]), + Pre = [#iset{vars=[#k_var{name=V}],arg=A} || + {{_,A},V} <- Pre0], + pre_seq(Pre++droplast(Exprs), last(Exprs)). + +extract_all_vars(Es, Forest, Acc0) -> + case extract_var_list(Es) of + [] -> + Acc0; + [_|_]=Vs0 -> + Vs = [V || V <- Vs0, maps:is_key(V, Forest)], + NewVs = ordsets:subtract(Vs, Acc0), + NewEs = [begin + {_,E} = maps:get(V, Forest), + E + end || V <- NewVs], + Acc = union(NewVs, Acc0), + extract_all_vars(NewEs, Forest, Acc) + end. + +extract_vars(#iset{arg=A,body=B}) -> + union(extract_vars(A), extract_vars(B)); +extract_vars(#k_bif{args=Args}) -> + ordsets:from_list(lit_list_vars(Args)); +extract_vars(#k_call{}) -> + []; +extract_vars(#k_test{args=Args}) -> + ordsets:from_list(lit_list_vars(Args)); +extract_vars(#k_match{body=Body}) -> + extract_vars(Body); +extract_vars(#k_alt{first=First,then=Then}) -> + union(extract_vars(First), extract_vars(Then)); +extract_vars(#k_guard{clauses=Cs}) -> + extract_var_list(Cs); +extract_vars(#k_guard_clause{guard=G}) -> + extract_vars(G); +extract_vars(#k_select{var=Var,types=Types}) -> + union(ordsets:from_list(lit_vars(Var)), + extract_var_list(Types)); +extract_vars(#k_type_clause{values=Values}) -> + extract_var_list(Values); +extract_vars(#k_val_clause{body=Body}) -> + extract_vars(Body); +extract_vars(#k_try{arg=Arg}) -> + extract_vars(Arg); +extract_vars(Lit) -> + ordsets:from_list(lit_vars(Lit)). + +extract_var_list(L) -> + union([extract_vars(E) || E <- L]). + %% Wrap the entire guard in a try/catch if needed. wrap_guard(#c_try{}=Try, St) -> {Try,St}; @@ -880,7 +1350,7 @@ new_fun_name(Type, #kern{func={F,Arity},fcount=C}=St) -> %% 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}}. + {list_to_atom("@k" ++ integer_to_list(C)),St#kern{vcount=C+1}}. %% new_var(State) -> {#k_var{},State}. @@ -1734,15 +2204,15 @@ 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, +uexpr(#k_try{anno=A,arg=A0,vars=Vs,body=B0,evars=Evs,handler=H0}, {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}; + {#k_protected{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), @@ -1791,13 +2261,9 @@ uexpr(#ifun{anno=A,vars=Vs,body=B0}, {break,Rs}, St0) -> 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], + op=#k_internal{name=make_fun,arity=length(Free)+2}, + args=[#k_atom{val=Fname},#k_int{val=Arity}|Fvs], ret=Rs}, Free,add_local_function(Fun, St)}; uexpr(Lit, {break,Rs0}, St0) -> |