diff options
| -rw-r--r-- | lib/compiler/src/sys_core_fold.erl | 88 | ||||
| -rw-r--r-- | lib/compiler/test/warnings_SUITE.erl | 26 |
2 files changed, 93 insertions, 21 deletions
diff --git a/lib/compiler/src/sys_core_fold.erl b/lib/compiler/src/sys_core_fold.erl index ea1959d0f8..f0f58c767d 100644 --- a/lib/compiler/src/sys_core_fold.erl +++ b/lib/compiler/src/sys_core_fold.erl @@ -2036,7 +2036,7 @@ is_bool_expr(#c_clause{body=B}, Sub) -> is_bool_expr(B, Sub); is_bool_expr(#c_let{vars=[V],arg=Arg,body=B}, Sub0) -> Sub = case is_bool_expr(Arg, Sub0) of - true -> update_types(V, [#c_literal{val=true}], Sub0); + true -> update_types(V, [bool], Sub0); false -> Sub0 end, is_bool_expr(B, Sub); @@ -2272,36 +2272,29 @@ opt_simple_let(#c_let{arg=Arg0}=Let, Ctxt, Sub0) -> opt_simple_let_1(#c_let{vars=Vs0,body=B0}=Let, Arg0, Ctxt, Sub0) -> %% Optimise let and add new substitutions. {Vs,Args,Sub1} = let_substs(Vs0, Arg0, Sub0), - BodySub = case {Vs,Args} of - {[V],[A]} -> - case is_bool_expr(A, Sub0) of - true -> - update_types(V, [#c_literal{val=true}], Sub1); - false -> - Sub1 - end; - {_,_} -> Sub1 - end, + BodySub = update_let_types(Vs, Args, Sub1), B = body(B0, Ctxt, BodySub), Arg = core_lib:make_values(Args), - opt_simple_let_2(Let, Vs, Arg, B, Ctxt, Sub1). + opt_simple_let_2(Let, Vs, Arg, B, B0, Ctxt, Sub1). -opt_simple_let_2(Let0, Vs0, Arg0, Body, Ctxt, Sub) -> +opt_simple_let_2(Let0, Vs0, Arg0, Body, PrevBody, Ctxt, Sub) -> case {Vs0,Arg0,Body} of - {[#c_var{name=N1}],Arg,#c_var{name=N2}} -> + {[#c_var{name=N1}],Arg1,#c_var{name=N2}} -> case N1 =:= N2 of true -> %% let <Var> = Arg in <Var> ==> Arg - Arg; + Arg1; false -> %% let <Var> = Arg in <OtherVar> ==> seq Arg OtherVar + Arg = maybe_suppress_warnings(Arg1, Vs0, PrevBody, Ctxt), expr(#c_seq{arg=Arg,body=Body}, Ctxt, sub_new_preserve_types(Sub)) end; {[],#c_values{es=[]},_} -> %% No variables left. Body; - {_,Arg,#c_literal{}} -> + {Vs,Arg1,#c_literal{}} -> + Arg = maybe_suppress_warnings(Arg1, Vs, PrevBody, Ctxt), E = case Ctxt of effect -> %% Throw away the literal body. @@ -2313,22 +2306,50 @@ opt_simple_let_2(Let0, Vs0, Arg0, Body, Ctxt, Sub) -> #c_seq{arg=Arg,body=Body} end, expr(E, Ctxt, sub_new_preserve_types(Sub)); - {Vs,Arg,Body} -> + {Vs,Arg1,Body} -> %% If none of the variables are used in the body, we can %% rewrite the let to a sequence: %% let <Var> = Arg in BodyWithoutVar ==> %% seq Arg BodyWithoutVar case is_any_var_used(Vs, Body) of false -> + Arg = maybe_suppress_warnings(Arg1, Vs, PrevBody, Ctxt), expr(#c_seq{arg=Arg,body=Body}, Ctxt, sub_new_preserve_types(Sub)); true -> - Let1 = Let0#c_let{vars=Vs,arg=Arg,body=Body}, + Let1 = Let0#c_let{vars=Vs,arg=Arg1,body=Body}, Let2 = opt_case_in_let(Let1, Sub), opt_case_in_let_arg(Let2, Ctxt, Sub) end end. +%% maybe_suppress_warnings(Arg, [#c_var{}], PreviousBody, Context) -> Arg' +%% Try to suppress false warnings when a variable is not used. +%% For instance, we don't expect a warning for useless building in: +%% +%% R = #r{}, %No warning expected. +%% R#r.f %Optimization would remove the reference to R. +%% +%% To avoid false warnings, we will check whether the variables were +%% referenced in the original unoptimized code. If they were, we will +%% consider the warning false and suppress it. + +maybe_suppress_warnings(Arg, _, _, effect) -> + %% Don't suppress any warnings in effect context. + Arg; +maybe_suppress_warnings(Arg, Vs, PrevBody, value) -> + case suppress_warning(Arg) of + true -> + Arg; %Already suppressed. + false -> + case is_any_var_used(Vs, PrevBody) of + true -> + cerl:set_ann(Arg, [compiler_generated]); + false -> + Arg + end + end. + move_case_into_arg(#c_case{arg=#c_let{vars=OuterVars0,arg=OuterArg, body=InnerArg0}=Outer, clauses=InnerClauses}=Inner, Sub) -> @@ -2504,8 +2525,37 @@ is_tuple_type(Var, Sub) -> yes_no(true) -> yes; yes_no(false) -> no. +%%% +%%% Update type information. +%%% + +update_let_types(Vs, Args, Sub) when is_list(Args) -> + update_let_types_1(Vs, Args, Sub); +update_let_types(_Vs, _Arg, Sub) -> + %% The argument is a complex expression (such as a 'case') + %% that returns multiple values. + Sub. + +update_let_types_1([#c_var{}=V|Vs], [A|As], Sub0) -> + Sub = update_types_from_expr(V, A, Sub0), + update_let_types_1(Vs, As, Sub); +update_let_types_1([], [], Sub) -> Sub. + +update_types_from_expr(V, Expr, Sub) -> + Type = extract_type(Expr, Sub), + update_types(V, [Type], Sub). + +extract_type(Expr, Sub) -> + case is_bool_expr(Expr, Sub) of + false -> Expr; + true -> bool + end. + %% update_types(Expr, Pattern, Sub) -> Sub' %% Update the type database. + +-spec update_types(cerl:cerl(), [type_info()], sub()) -> sub(). + update_types(Expr, Pat, #sub{t=Tdb0}=Sub) -> Tdb = update_types_1(Expr, Pat, Tdb0), Sub#sub{t=Tdb}. @@ -2525,6 +2575,8 @@ update_types_2(V, [#c_tuple{}=P], Types) -> orddict:store(V, P, Types); update_types_2(V, [#c_literal{val=Bool}], Types) when is_boolean(Bool) -> orddict:store(V, bool, Types); +update_types_2(V, [Type], Types) when is_atom(Type) -> + orddict:store(V, Type, Types); update_types_2(_, _, Types) -> Types. %% kill_types(V, Tdb) -> Tdb' diff --git a/lib/compiler/test/warnings_SUITE.erl b/lib/compiler/test/warnings_SUITE.erl index dcd3910926..d0b7c71be8 100644 --- a/lib/compiler/test/warnings_SUITE.erl +++ b/lib/compiler/test/warnings_SUITE.erl @@ -39,7 +39,7 @@ guard/1,bad_arith/1,bool_cases/1,bad_apply/1, files/1,effect/1,bin_opt_info/1,bin_construction/1, comprehensions/1,maps/1,redundant_boolean_clauses/1, - latin1_fallback/1,underscore/1]). + latin1_fallback/1,underscore/1,no_warnings/1]). % Default timetrap timeout (set in init_per_testcase). -define(default_timeout, ?t:minutes(2)). @@ -65,7 +65,7 @@ groups() -> bad_arith,bool_cases,bad_apply,files,effect, bin_opt_info,bin_construction,comprehensions,maps, redundant_boolean_clauses,latin1_fallback, - underscore]}]. + underscore,no_warnings]}]. init_per_suite(Config) -> Config. @@ -281,7 +281,6 @@ bad_arith(Config) when is_list(Config) -> {3,sys_core_fold,{eval_failure,badarith}}, {9,sys_core_fold,nomatch_guard}, {9,sys_core_fold,{eval_failure,badarith}}, - {9,sys_core_fold,{no_effect,{erlang,is_integer,1}}}, {10,sys_core_fold,nomatch_guard}, {10,sys_core_fold,{eval_failure,badarith}}, {15,sys_core_fold,{eval_failure,badarith}} @@ -719,6 +718,27 @@ underscore(Config) when is_list(Config) -> ok. +no_warnings(Config) when is_list(Config) -> + Ts = [{no_warnings, + <<"-record(r, {s=ordsets:new(),a,b}). + + a() -> + R = #r{}, %No warning expected. + {R#r.a,R#r.b}. + + b(X) -> + T = true, + Var = [X], %No warning expected. + case T of + false -> Var; + true -> [] + end. + ">>, + [], + []}], + run(Config, Ts), + ok. + %%% %%% End of test cases. %%% |