diff options
| -rw-r--r-- | lib/compiler/src/sys_core_fold.erl | 99 | ||||
| -rw-r--r-- | lib/compiler/test/core_fold_SUITE.erl | 38 |
2 files changed, 105 insertions, 32 deletions
diff --git a/lib/compiler/src/sys_core_fold.erl b/lib/compiler/src/sys_core_fold.erl index 2dc2dd51ff..46816fe24a 100644 --- a/lib/compiler/src/sys_core_fold.erl +++ b/lib/compiler/src/sys_core_fold.erl @@ -145,14 +145,9 @@ find_fixpoint(OptFun, Core0, Max) -> body(Body, Sub) -> body(Body, value, Sub). -body(#c_values{anno=A,es=Es0}, Ctxt, Sub) -> - Es1 = expr_list(Es0, Ctxt, Sub), - case Ctxt of - value -> - #c_values{anno=A,es=Es1}; - effect -> - make_effect_seq(Es1, Sub) - end; +body(#c_values{anno=A,es=Es0}, value, Sub) -> + Es1 = expr_list(Es0, value, Sub), + #c_values{anno=A,es=Es1}; body(E, Ctxt, Sub) -> ?ASSERT(verify_scope(E, Sub)), expr(E, Ctxt, Sub). @@ -2687,22 +2682,73 @@ opt_simple_let_2(Let0, Vs0, Arg0, Body, PrevBody, Sub) -> {[],#c_values{es=[]},_} -> %% No variables left. 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), - #c_seq{arg=Arg,body=Body}; - true -> - Let1 = Let0#c_let{vars=Vs,arg=Arg1,body=Body}, - opt_bool_case_in_let(Let1, Sub) + {[#c_var{name=V}=Var|Vars]=Vars0,Arg1,Body} -> + case core_lib:is_var_used(V, Body) of + false when Vars =:= [] -> + %% If the variable is not used in the body, we can + %% rewrite the let to a sequence: + %% let <Var> = Arg in BodyWithoutVar ==> + %% seq Arg BodyWithoutVar + Arg = maybe_suppress_warnings(Arg1, Var, PrevBody), + #c_seq{arg=Arg,body=Body}; + false -> + %% There are multiple values returned by the argument + %% and the first value is not used (this is a 'case' + %% with exported variables, but the return value is + %% ignored). We can remove the first variable and the + %% the first value returned from the 'let' argument. + Arg2 = remove_first_value(Arg1, Sub), + Let1 = Let0#c_let{vars=Vars,arg=Arg2,body=Body}, + post_opt_let(Let1, Sub); + true -> + Let1 = Let0#c_let{vars=Vars0,arg=Arg1,body=Body}, + post_opt_let(Let1, Sub) end end. -%% maybe_suppress_warnings(Arg, [#c_var{}], PreviousBody) -> Arg' +%% post_opt_let(Let, Sub) +%% Final optimizations of the let. +%% +%% Note that the substitutions and scope in Sub have been cleared +%% and should not be used. + +post_opt_let(Let, Sub) -> + opt_bool_case_in_let(Let, Sub). + + +%% remove_first_value(Core0, Sub) -> Core. +%% Core0 is an expression that returns at least two values. +%% Remove the first value returned from Core0. + +remove_first_value(#c_values{es=[V|Vs]}, Sub) -> + Values = core_lib:make_values(Vs), + case is_safe_simple(V, Sub) of + false -> + #c_seq{arg=V,body=Values}; + true -> + Values + end; +remove_first_value(#c_case{clauses=Cs0}=Core, Sub) -> + Cs = remove_first_value_cs(Cs0, Sub), + Core#c_case{clauses=Cs}; +remove_first_value(#c_receive{clauses=Cs0,action=Act0}=Core, Sub) -> + Cs = remove_first_value_cs(Cs0, Sub), + Act = remove_first_value(Act0, Sub), + Core#c_receive{clauses=Cs,action=Act}; +remove_first_value(#c_let{body=B}=Core, Sub) -> + Core#c_let{body=remove_first_value(B, Sub)}; +remove_first_value(#c_seq{body=B}=Core, Sub) -> + Core#c_seq{body=remove_first_value(B, Sub)}; +remove_first_value(#c_primop{}=Core, _Sub) -> + Core; +remove_first_value(#c_call{}=Core, _Sub) -> + Core. + +remove_first_value_cs(Cs, Sub) -> + [C#c_clause{body=remove_first_value(B, Sub)} || + #c_clause{body=B}=C <- Cs]. + +%% maybe_suppress_warnings(Arg, #c_var{}, PreviousBody) -> Arg' %% Try to suppress false warnings when a variable is not used. %% For instance, we don't expect a warning for useless building in: %% @@ -2713,12 +2759,12 @@ opt_simple_let_2(Let0, Vs0, Arg0, Body, PrevBody, Sub) -> %% referenced in the original unoptimized code. If they were, we will %% consider the warning false and suppress it. -maybe_suppress_warnings(Arg, Vs, PrevBody) -> +maybe_suppress_warnings(Arg, #c_var{name=V}, PrevBody) -> case should_suppress_warning(Arg) of true -> Arg; %Already suppressed. false -> - case is_any_var_used(Vs, PrevBody) of + case core_lib:is_var_used(V, PrevBody) of true -> suppress_warning([Arg]); false -> @@ -2826,13 +2872,6 @@ move_case_into_arg(#c_case{arg=#c_seq{arg=OuterArg,body=InnerArg}=Outer, move_case_into_arg(Expr, _) -> Expr. -is_any_var_used([#c_var{name=V}|Vs], Expr) -> - case core_lib:is_var_used(V, Expr) of - false -> is_any_var_used(Vs, Expr); - true -> true - end; -is_any_var_used([], _) -> false. - %%% %%% Retrieving information about types. %%% diff --git a/lib/compiler/test/core_fold_SUITE.erl b/lib/compiler/test/core_fold_SUITE.erl index 262967d03d..4fd1f84569 100644 --- a/lib/compiler/test/core_fold_SUITE.erl +++ b/lib/compiler/test/core_fold_SUITE.erl @@ -27,7 +27,7 @@ multiple_aliases/1,redundant_boolean_clauses/1, mixed_matching_clauses/1,unnecessary_building/1, no_no_file/1,configuration/1,supplies/1, - redundant_stack_frame/1]). + redundant_stack_frame/1,export_from_case/1]). -export([foo/0,foo/1,foo/2,foo/3]). @@ -47,7 +47,7 @@ groups() -> multiple_aliases,redundant_boolean_clauses, mixed_matching_clauses,unnecessary_building, no_no_file,configuration,supplies, - redundant_stack_frame]}]. + redundant_stack_frame,export_from_case]}]. init_per_suite(Config) -> @@ -551,4 +551,38 @@ do_redundant_stack_frame(Map) -> end, {X, Y}. +%% Cover some clauses in sys_core_fold:remove_first_value/2. + +-record(export_from_case, {val}). + +export_from_case(_Config) -> + a = export_from_case_1(true), + b = export_from_case_1(false), + + R = #export_from_case{val=0}, + {ok,R} = export_from_case_2(false, R), + {ok,#export_from_case{val=42}} = export_from_case_2(true, R), + + ok. + +export_from_case_1(Bool) -> + case Bool of + true -> + id(42), + Result = a; + false -> + Result = b + end, + id(Result). + +export_from_case_2(Bool, Rec) -> + case Bool of + false -> + Result = Rec; + true -> + Result = Rec#export_from_case{val=42} + end, + {ok,Result}. + + id(I) -> I. |