diff options
| -rw-r--r-- | lib/compiler/src/beam_ssa_type.erl | 48 |
1 files changed, 26 insertions, 22 deletions
diff --git a/lib/compiler/src/beam_ssa_type.erl b/lib/compiler/src/beam_ssa_type.erl index 34cdd0d663..57fd7fec60 100644 --- a/lib/compiler/src/beam_ssa_type.erl +++ b/lib/compiler/src/beam_ssa_type.erl @@ -23,7 +23,7 @@ -include("beam_ssa_opt.hrl"). -import(lists, [all/2,any/2,droplast/1,foldl/3,last/1,member/2, - keyfind/3,partition/2,reverse/1,reverse/2, + keyfind/3,reverse/1,reverse/2, sort/1,split/2]). -define(UNICODE_INT, #t_integer{elements={0,16#10FFFF}}). @@ -1392,24 +1392,11 @@ get_type(#b_literal{val=Val}, _Ts) -> %% type for L. For example, if L was known to be 'list', subtracting %% 'cons' would give 'nil' as the only possible type. The result of the %% subtraction for L will be added to FailTypes. -%% -%% Here is another example, asking about the variable Bool: -%% -%% Head = bif:hd L -%% Bool = succeeded Head -%% -%% 'succeeded Head' will evaluate to 'true' if the instrution that -%% defined Head succeeded. In this case, it is the 'bif:hd L' -%% instruction, which will succeed if L is 'cons'. Thus, the meet of -%% the previous type for L and 'cons' will be added to SuccTypes. -%% -%% If 'succeeded Head' evaluates to 'false', it means that 'bif:hd L' -%% failed and that L is not 'cons'. 'cons' can be subtracted from the -%% previously known type for L and the result put in FailTypes. infer_types_br(#b_var{}=V, Ts, #d{ds=Ds}) -> #{V:=#b_set{op=Op,args=Args}} = Ds, - Types0 = infer_type(Op, Args, Ds), + PosTypes0 = infer_type(Op, Args, Ds), + NegTypes0 = infer_type_negative(Op, Args, Ds), %% We must be careful with types inferred from '=:='. %% @@ -1420,13 +1407,17 @@ infer_types_br(#b_var{}=V, Ts, #d{ds=Ds}) -> %% %% However, it is safe to subtract a type inferred from '=:=' if %% it is single-valued, e.g. if it is [] or the atom 'true'. - EqTypes0 = infer_eq_type(Op, Args, Ts, Ds), - {Types1,EqTypes} = partition(fun({_,T}) -> - is_singleton_type(T) - end, EqTypes0), - Types = Types1 ++ Types0, - {meet_types(EqTypes++Types, Ts),subtract_types(Types, Ts)}. + EqTypes = infer_eq_type(Op, Args, Ts, Ds), + NegTypes1 = [P || {_,T}=P <- EqTypes, is_singleton_type(T)], + + PosTypes = EqTypes ++ PosTypes0, + SuccTs = meet_types(PosTypes, Ts), + + NegTypes = NegTypes0 ++ NegTypes1, + FailTs = subtract_types(NegTypes, Ts), + + {SuccTs,FailTs}. infer_types_switch(V, Lit, Ts, #d{ds=Ds}) -> Types = infer_eq_type({bif,'=:='}, [V, Lit], Ts, Ds), @@ -1461,6 +1452,19 @@ infer_eq_lit(#b_set{op=get_tuple_element, [{Tuple,#t_tuple{size=Index,elements=Es}}]; infer_eq_lit(_, _) -> []. +infer_type_negative(Op, Args, Ds) -> + case is_negative_inference_safe(Op, Args) of + true -> + infer_type(Op, Args, Ds); + false -> + [] + end. + +%% Conservative list of instructions for which negative +%% inference is safe. +is_negative_inference_safe(is_nonempty_list, _Args) -> true; +is_negative_inference_safe(_, _) -> false. + infer_type({bif,element}, [#b_literal{val=Pos},#b_var{}=Tuple], _Ds) -> if is_integer(Pos), 1 =< Pos -> |